| File: | src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp |
| Warning: | line 780, column 37 Called C++ object pointer is null |
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| 1 | //===-- ControlHeightReduction.cpp - Control Height Reduction -------------===// | |||
| 2 | // | |||
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. | |||
| 4 | // See https://llvm.org/LICENSE.txt for license information. | |||
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | |||
| 6 | // | |||
| 7 | //===----------------------------------------------------------------------===// | |||
| 8 | // | |||
| 9 | // This pass merges conditional blocks of code and reduces the number of | |||
| 10 | // conditional branches in the hot paths based on profiles. | |||
| 11 | // | |||
| 12 | //===----------------------------------------------------------------------===// | |||
| 13 | ||||
| 14 | #include "llvm/Transforms/Instrumentation/ControlHeightReduction.h" | |||
| 15 | #include "llvm/ADT/DenseMap.h" | |||
| 16 | #include "llvm/ADT/DenseSet.h" | |||
| 17 | #include "llvm/ADT/SmallVector.h" | |||
| 18 | #include "llvm/ADT/StringSet.h" | |||
| 19 | #include "llvm/Analysis/BlockFrequencyInfo.h" | |||
| 20 | #include "llvm/Analysis/GlobalsModRef.h" | |||
| 21 | #include "llvm/Analysis/OptimizationRemarkEmitter.h" | |||
| 22 | #include "llvm/Analysis/ProfileSummaryInfo.h" | |||
| 23 | #include "llvm/Analysis/RegionInfo.h" | |||
| 24 | #include "llvm/Analysis/RegionIterator.h" | |||
| 25 | #include "llvm/Analysis/ValueTracking.h" | |||
| 26 | #include "llvm/IR/CFG.h" | |||
| 27 | #include "llvm/IR/Dominators.h" | |||
| 28 | #include "llvm/IR/IRBuilder.h" | |||
| 29 | #include "llvm/IR/MDBuilder.h" | |||
| 30 | #include "llvm/IR/PassManager.h" | |||
| 31 | #include "llvm/InitializePasses.h" | |||
| 32 | #include "llvm/Support/BranchProbability.h" | |||
| 33 | #include "llvm/Support/CommandLine.h" | |||
| 34 | #include "llvm/Support/MemoryBuffer.h" | |||
| 35 | #include "llvm/Transforms/Utils.h" | |||
| 36 | #include "llvm/Transforms/Utils/BasicBlockUtils.h" | |||
| 37 | #include "llvm/Transforms/Utils/Cloning.h" | |||
| 38 | #include "llvm/Transforms/Utils/ValueMapper.h" | |||
| 39 | ||||
| 40 | #include <set> | |||
| 41 | #include <sstream> | |||
| 42 | ||||
| 43 | using namespace llvm; | |||
| 44 | ||||
| 45 | #define DEBUG_TYPE"chr" "chr" | |||
| 46 | ||||
| 47 | #define CHR_DEBUG(X)do { } while (false) LLVM_DEBUG(X)do { } while (false) | |||
| 48 | ||||
| 49 | static cl::opt<bool> ForceCHR("force-chr", cl::init(false), cl::Hidden, | |||
| 50 | cl::desc("Apply CHR for all functions")); | |||
| 51 | ||||
| 52 | static cl::opt<double> CHRBiasThreshold( | |||
| 53 | "chr-bias-threshold", cl::init(0.99), cl::Hidden, | |||
| 54 | cl::desc("CHR considers a branch bias greater than this ratio as biased")); | |||
| 55 | ||||
| 56 | static cl::opt<unsigned> CHRMergeThreshold( | |||
| 57 | "chr-merge-threshold", cl::init(2), cl::Hidden, | |||
| 58 | cl::desc("CHR merges a group of N branches/selects where N >= this value")); | |||
| 59 | ||||
| 60 | static cl::opt<std::string> CHRModuleList( | |||
| 61 | "chr-module-list", cl::init(""), cl::Hidden, | |||
| 62 | cl::desc("Specify file to retrieve the list of modules to apply CHR to")); | |||
| 63 | ||||
| 64 | static cl::opt<std::string> CHRFunctionList( | |||
| 65 | "chr-function-list", cl::init(""), cl::Hidden, | |||
| 66 | cl::desc("Specify file to retrieve the list of functions to apply CHR to")); | |||
| 67 | ||||
| 68 | static StringSet<> CHRModules; | |||
| 69 | static StringSet<> CHRFunctions; | |||
| 70 | ||||
| 71 | static void parseCHRFilterFiles() { | |||
| 72 | if (!CHRModuleList.empty()) { | |||
| 73 | auto FileOrErr = MemoryBuffer::getFile(CHRModuleList); | |||
| 74 | if (!FileOrErr) { | |||
| 75 | errs() << "Error: Couldn't read the chr-module-list file " << CHRModuleList << "\n"; | |||
| 76 | std::exit(1); | |||
| 77 | } | |||
| 78 | StringRef Buf = FileOrErr->get()->getBuffer(); | |||
| 79 | SmallVector<StringRef, 0> Lines; | |||
| 80 | Buf.split(Lines, '\n'); | |||
| 81 | for (StringRef Line : Lines) { | |||
| 82 | Line = Line.trim(); | |||
| 83 | if (!Line.empty()) | |||
| 84 | CHRModules.insert(Line); | |||
| 85 | } | |||
| 86 | } | |||
| 87 | if (!CHRFunctionList.empty()) { | |||
| 88 | auto FileOrErr = MemoryBuffer::getFile(CHRFunctionList); | |||
| 89 | if (!FileOrErr) { | |||
| 90 | errs() << "Error: Couldn't read the chr-function-list file " << CHRFunctionList << "\n"; | |||
| 91 | std::exit(1); | |||
| 92 | } | |||
| 93 | StringRef Buf = FileOrErr->get()->getBuffer(); | |||
| 94 | SmallVector<StringRef, 0> Lines; | |||
| 95 | Buf.split(Lines, '\n'); | |||
| 96 | for (StringRef Line : Lines) { | |||
| 97 | Line = Line.trim(); | |||
| 98 | if (!Line.empty()) | |||
| 99 | CHRFunctions.insert(Line); | |||
| 100 | } | |||
| 101 | } | |||
| 102 | } | |||
| 103 | ||||
| 104 | namespace { | |||
| 105 | class ControlHeightReductionLegacyPass : public FunctionPass { | |||
| 106 | public: | |||
| 107 | static char ID; | |||
| 108 | ||||
| 109 | ControlHeightReductionLegacyPass() : FunctionPass(ID) { | |||
| 110 | initializeControlHeightReductionLegacyPassPass( | |||
| 111 | *PassRegistry::getPassRegistry()); | |||
| 112 | parseCHRFilterFiles(); | |||
| 113 | } | |||
| 114 | ||||
| 115 | bool runOnFunction(Function &F) override; | |||
| 116 | void getAnalysisUsage(AnalysisUsage &AU) const override { | |||
| 117 | AU.addRequired<BlockFrequencyInfoWrapperPass>(); | |||
| 118 | AU.addRequired<DominatorTreeWrapperPass>(); | |||
| 119 | AU.addRequired<ProfileSummaryInfoWrapperPass>(); | |||
| 120 | AU.addRequired<RegionInfoPass>(); | |||
| 121 | AU.addPreserved<GlobalsAAWrapperPass>(); | |||
| 122 | } | |||
| 123 | }; | |||
| 124 | } // end anonymous namespace | |||
| 125 | ||||
| 126 | char ControlHeightReductionLegacyPass::ID = 0; | |||
| 127 | ||||
| 128 | INITIALIZE_PASS_BEGIN(ControlHeightReductionLegacyPass,static void *initializeControlHeightReductionLegacyPassPassOnce (PassRegistry &Registry) { | |||
| 129 | "chr",static void *initializeControlHeightReductionLegacyPassPassOnce (PassRegistry &Registry) { | |||
| 130 | "Reduce control height in the hot paths",static void *initializeControlHeightReductionLegacyPassPassOnce (PassRegistry &Registry) { | |||
| 131 | false, false)static void *initializeControlHeightReductionLegacyPassPassOnce (PassRegistry &Registry) { | |||
| 132 | INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass)initializeBlockFrequencyInfoWrapperPassPass(Registry); | |||
| 133 | INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry); | |||
| 134 | INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)initializeProfileSummaryInfoWrapperPassPass(Registry); | |||
| 135 | INITIALIZE_PASS_DEPENDENCY(RegionInfoPass)initializeRegionInfoPassPass(Registry); | |||
| 136 | INITIALIZE_PASS_END(ControlHeightReductionLegacyPass,PassInfo *PI = new PassInfo( "Reduce control height in the hot paths" , "chr", &ControlHeightReductionLegacyPass::ID, PassInfo:: NormalCtor_t(callDefaultCtor<ControlHeightReductionLegacyPass >), false, false); Registry.registerPass(*PI, true); return PI; } static llvm::once_flag InitializeControlHeightReductionLegacyPassPassFlag ; void llvm::initializeControlHeightReductionLegacyPassPass(PassRegistry &Registry) { llvm::call_once(InitializeControlHeightReductionLegacyPassPassFlag , initializeControlHeightReductionLegacyPassPassOnce, std::ref (Registry)); } | |||
| 137 | "chr",PassInfo *PI = new PassInfo( "Reduce control height in the hot paths" , "chr", &ControlHeightReductionLegacyPass::ID, PassInfo:: NormalCtor_t(callDefaultCtor<ControlHeightReductionLegacyPass >), false, false); Registry.registerPass(*PI, true); return PI; } static llvm::once_flag InitializeControlHeightReductionLegacyPassPassFlag ; void llvm::initializeControlHeightReductionLegacyPassPass(PassRegistry &Registry) { llvm::call_once(InitializeControlHeightReductionLegacyPassPassFlag , initializeControlHeightReductionLegacyPassPassOnce, std::ref (Registry)); } | |||
| 138 | "Reduce control height in the hot paths",PassInfo *PI = new PassInfo( "Reduce control height in the hot paths" , "chr", &ControlHeightReductionLegacyPass::ID, PassInfo:: NormalCtor_t(callDefaultCtor<ControlHeightReductionLegacyPass >), false, false); Registry.registerPass(*PI, true); return PI; } static llvm::once_flag InitializeControlHeightReductionLegacyPassPassFlag ; void llvm::initializeControlHeightReductionLegacyPassPass(PassRegistry &Registry) { llvm::call_once(InitializeControlHeightReductionLegacyPassPassFlag , initializeControlHeightReductionLegacyPassPassOnce, std::ref (Registry)); } | |||
| 139 | false, false)PassInfo *PI = new PassInfo( "Reduce control height in the hot paths" , "chr", &ControlHeightReductionLegacyPass::ID, PassInfo:: NormalCtor_t(callDefaultCtor<ControlHeightReductionLegacyPass >), false, false); Registry.registerPass(*PI, true); return PI; } static llvm::once_flag InitializeControlHeightReductionLegacyPassPassFlag ; void llvm::initializeControlHeightReductionLegacyPassPass(PassRegistry &Registry) { llvm::call_once(InitializeControlHeightReductionLegacyPassPassFlag , initializeControlHeightReductionLegacyPassPassOnce, std::ref (Registry)); } | |||
| 140 | ||||
| 141 | FunctionPass *llvm::createControlHeightReductionLegacyPass() { | |||
| 142 | return new ControlHeightReductionLegacyPass(); | |||
| 143 | } | |||
| 144 | ||||
| 145 | namespace { | |||
| 146 | ||||
| 147 | struct CHRStats { | |||
| 148 | CHRStats() : NumBranches(0), NumBranchesDelta(0), | |||
| 149 | WeightedNumBranchesDelta(0) {} | |||
| 150 | void print(raw_ostream &OS) const { | |||
| 151 | OS << "CHRStats: NumBranches " << NumBranches | |||
| 152 | << " NumBranchesDelta " << NumBranchesDelta | |||
| 153 | << " WeightedNumBranchesDelta " << WeightedNumBranchesDelta; | |||
| 154 | } | |||
| 155 | uint64_t NumBranches; // The original number of conditional branches / | |||
| 156 | // selects | |||
| 157 | uint64_t NumBranchesDelta; // The decrease of the number of conditional | |||
| 158 | // branches / selects in the hot paths due to CHR. | |||
| 159 | uint64_t WeightedNumBranchesDelta; // NumBranchesDelta weighted by the profile | |||
| 160 | // count at the scope entry. | |||
| 161 | }; | |||
| 162 | ||||
| 163 | // RegInfo - some properties of a Region. | |||
| 164 | struct RegInfo { | |||
| 165 | RegInfo() : R(nullptr), HasBranch(false) {} | |||
| 166 | RegInfo(Region *RegionIn) : R(RegionIn), HasBranch(false) {} | |||
| 167 | Region *R; | |||
| 168 | bool HasBranch; | |||
| 169 | SmallVector<SelectInst *, 8> Selects; | |||
| 170 | }; | |||
| 171 | ||||
| 172 | typedef DenseMap<Region *, DenseSet<Instruction *>> HoistStopMapTy; | |||
| 173 | ||||
| 174 | // CHRScope - a sequence of regions to CHR together. It corresponds to a | |||
| 175 | // sequence of conditional blocks. It can have subscopes which correspond to | |||
| 176 | // nested conditional blocks. Nested CHRScopes form a tree. | |||
| 177 | class CHRScope { | |||
| 178 | public: | |||
| 179 | CHRScope(RegInfo RI) : BranchInsertPoint(nullptr) { | |||
| 180 | assert(RI.R && "Null RegionIn")((void)0); | |||
| 181 | RegInfos.push_back(RI); | |||
| 182 | } | |||
| 183 | ||||
| 184 | Region *getParentRegion() { | |||
| 185 | assert(RegInfos.size() > 0 && "Empty CHRScope")((void)0); | |||
| 186 | Region *Parent = RegInfos[0].R->getParent(); | |||
| 187 | assert(Parent && "Unexpected to call this on the top-level region")((void)0); | |||
| 188 | return Parent; | |||
| 189 | } | |||
| 190 | ||||
| 191 | BasicBlock *getEntryBlock() { | |||
| 192 | assert(RegInfos.size() > 0 && "Empty CHRScope")((void)0); | |||
| 193 | return RegInfos.front().R->getEntry(); | |||
| 194 | } | |||
| 195 | ||||
| 196 | BasicBlock *getExitBlock() { | |||
| 197 | assert(RegInfos.size() > 0 && "Empty CHRScope")((void)0); | |||
| 198 | return RegInfos.back().R->getExit(); | |||
| 199 | } | |||
| 200 | ||||
| 201 | bool appendable(CHRScope *Next) { | |||
| 202 | // The next scope is appendable only if this scope is directly connected to | |||
| 203 | // it (which implies it post-dominates this scope) and this scope dominates | |||
| 204 | // it (no edge to the next scope outside this scope). | |||
| 205 | BasicBlock *NextEntry = Next->getEntryBlock(); | |||
| 206 | if (getExitBlock() != NextEntry) | |||
| 207 | // Not directly connected. | |||
| 208 | return false; | |||
| 209 | Region *LastRegion = RegInfos.back().R; | |||
| 210 | for (BasicBlock *Pred : predecessors(NextEntry)) | |||
| 211 | if (!LastRegion->contains(Pred)) | |||
| 212 | // There's an edge going into the entry of the next scope from outside | |||
| 213 | // of this scope. | |||
| 214 | return false; | |||
| 215 | return true; | |||
| 216 | } | |||
| 217 | ||||
| 218 | void append(CHRScope *Next) { | |||
| 219 | assert(RegInfos.size() > 0 && "Empty CHRScope")((void)0); | |||
| 220 | assert(Next->RegInfos.size() > 0 && "Empty CHRScope")((void)0); | |||
| 221 | assert(getParentRegion() == Next->getParentRegion() &&((void)0) | |||
| 222 | "Must be siblings")((void)0); | |||
| 223 | assert(getExitBlock() == Next->getEntryBlock() &&((void)0) | |||
| 224 | "Must be adjacent")((void)0); | |||
| 225 | RegInfos.append(Next->RegInfos.begin(), Next->RegInfos.end()); | |||
| 226 | Subs.append(Next->Subs.begin(), Next->Subs.end()); | |||
| 227 | } | |||
| 228 | ||||
| 229 | void addSub(CHRScope *SubIn) { | |||
| 230 | #ifndef NDEBUG1 | |||
| 231 | bool IsChild = false; | |||
| 232 | for (RegInfo &RI : RegInfos) | |||
| 233 | if (RI.R == SubIn->getParentRegion()) { | |||
| 234 | IsChild = true; | |||
| 235 | break; | |||
| 236 | } | |||
| 237 | assert(IsChild && "Must be a child")((void)0); | |||
| 238 | #endif | |||
| 239 | Subs.push_back(SubIn); | |||
| 240 | } | |||
| 241 | ||||
| 242 | // Split this scope at the boundary region into two, which will belong to the | |||
| 243 | // tail and returns the tail. | |||
| 244 | CHRScope *split(Region *Boundary) { | |||
| 245 | assert(Boundary && "Boundary null")((void)0); | |||
| 246 | assert(RegInfos.begin()->R != Boundary &&((void)0) | |||
| 247 | "Can't be split at beginning")((void)0); | |||
| 248 | auto BoundaryIt = llvm::find_if( | |||
| 249 | RegInfos, [&Boundary](const RegInfo &RI) { return Boundary == RI.R; }); | |||
| 250 | if (BoundaryIt == RegInfos.end()) | |||
| 251 | return nullptr; | |||
| 252 | ArrayRef<RegInfo> TailRegInfos(BoundaryIt, RegInfos.end()); | |||
| 253 | DenseSet<Region *> TailRegionSet; | |||
| 254 | for (const RegInfo &RI : TailRegInfos) | |||
| 255 | TailRegionSet.insert(RI.R); | |||
| 256 | ||||
| 257 | auto TailIt = | |||
| 258 | std::stable_partition(Subs.begin(), Subs.end(), [&](CHRScope *Sub) { | |||
| 259 | assert(Sub && "null Sub")((void)0); | |||
| 260 | Region *Parent = Sub->getParentRegion(); | |||
| 261 | if (TailRegionSet.count(Parent)) | |||
| 262 | return false; | |||
| 263 | ||||
| 264 | assert(llvm::any_of(((void)0) | |||
| 265 | RegInfos,((void)0) | |||
| 266 | [&Parent](const RegInfo &RI) { return Parent == RI.R; }) &&((void)0) | |||
| 267 | "Must be in head")((void)0); | |||
| 268 | return true; | |||
| 269 | }); | |||
| 270 | ArrayRef<CHRScope *> TailSubs(TailIt, Subs.end()); | |||
| 271 | ||||
| 272 | assert(HoistStopMap.empty() && "MapHoistStops must be empty")((void)0); | |||
| 273 | auto *Scope = new CHRScope(TailRegInfos, TailSubs); | |||
| 274 | RegInfos.erase(BoundaryIt, RegInfos.end()); | |||
| 275 | Subs.erase(TailIt, Subs.end()); | |||
| 276 | return Scope; | |||
| 277 | } | |||
| 278 | ||||
| 279 | bool contains(Instruction *I) const { | |||
| 280 | BasicBlock *Parent = I->getParent(); | |||
| 281 | for (const RegInfo &RI : RegInfos) | |||
| 282 | if (RI.R->contains(Parent)) | |||
| 283 | return true; | |||
| 284 | return false; | |||
| 285 | } | |||
| 286 | ||||
| 287 | void print(raw_ostream &OS) const; | |||
| 288 | ||||
| 289 | SmallVector<RegInfo, 8> RegInfos; // Regions that belong to this scope | |||
| 290 | SmallVector<CHRScope *, 8> Subs; // Subscopes. | |||
| 291 | ||||
| 292 | // The instruction at which to insert the CHR conditional branch (and hoist | |||
| 293 | // the dependent condition values). | |||
| 294 | Instruction *BranchInsertPoint; | |||
| 295 | ||||
| 296 | // True-biased and false-biased regions (conditional blocks), | |||
| 297 | // respectively. Used only for the outermost scope and includes regions in | |||
| 298 | // subscopes. The rest are unbiased. | |||
| 299 | DenseSet<Region *> TrueBiasedRegions; | |||
| 300 | DenseSet<Region *> FalseBiasedRegions; | |||
| 301 | // Among the biased regions, the regions that get CHRed. | |||
| 302 | SmallVector<RegInfo, 8> CHRRegions; | |||
| 303 | ||||
| 304 | // True-biased and false-biased selects, respectively. Used only for the | |||
| 305 | // outermost scope and includes ones in subscopes. | |||
| 306 | DenseSet<SelectInst *> TrueBiasedSelects; | |||
| 307 | DenseSet<SelectInst *> FalseBiasedSelects; | |||
| 308 | ||||
| 309 | // Map from one of the above regions to the instructions to stop | |||
| 310 | // hoisting instructions at through use-def chains. | |||
| 311 | HoistStopMapTy HoistStopMap; | |||
| 312 | ||||
| 313 | private: | |||
| 314 | CHRScope(ArrayRef<RegInfo> RegInfosIn, ArrayRef<CHRScope *> SubsIn) | |||
| 315 | : RegInfos(RegInfosIn.begin(), RegInfosIn.end()), | |||
| 316 | Subs(SubsIn.begin(), SubsIn.end()), BranchInsertPoint(nullptr) {} | |||
| 317 | }; | |||
| 318 | ||||
| 319 | class CHR { | |||
| 320 | public: | |||
| 321 | CHR(Function &Fin, BlockFrequencyInfo &BFIin, DominatorTree &DTin, | |||
| 322 | ProfileSummaryInfo &PSIin, RegionInfo &RIin, | |||
| 323 | OptimizationRemarkEmitter &OREin) | |||
| 324 | : F(Fin), BFI(BFIin), DT(DTin), PSI(PSIin), RI(RIin), ORE(OREin) {} | |||
| 325 | ||||
| 326 | ~CHR() { | |||
| 327 | for (CHRScope *Scope : Scopes) { | |||
| 328 | delete Scope; | |||
| 329 | } | |||
| 330 | } | |||
| 331 | ||||
| 332 | bool run(); | |||
| 333 | ||||
| 334 | private: | |||
| 335 | // See the comments in CHR::run() for the high level flow of the algorithm and | |||
| 336 | // what the following functions do. | |||
| 337 | ||||
| 338 | void findScopes(SmallVectorImpl<CHRScope *> &Output) { | |||
| 339 | Region *R = RI.getTopLevelRegion(); | |||
| 340 | if (CHRScope *Scope = findScopes(R, nullptr, nullptr, Output)) { | |||
| 341 | Output.push_back(Scope); | |||
| 342 | } | |||
| 343 | } | |||
| 344 | CHRScope *findScopes(Region *R, Region *NextRegion, Region *ParentRegion, | |||
| 345 | SmallVectorImpl<CHRScope *> &Scopes); | |||
| 346 | CHRScope *findScope(Region *R); | |||
| 347 | void checkScopeHoistable(CHRScope *Scope); | |||
| 348 | ||||
| 349 | void splitScopes(SmallVectorImpl<CHRScope *> &Input, | |||
| 350 | SmallVectorImpl<CHRScope *> &Output); | |||
| 351 | SmallVector<CHRScope *, 8> splitScope(CHRScope *Scope, | |||
| 352 | CHRScope *Outer, | |||
| 353 | DenseSet<Value *> *OuterConditionValues, | |||
| 354 | Instruction *OuterInsertPoint, | |||
| 355 | SmallVectorImpl<CHRScope *> &Output, | |||
| 356 | DenseSet<Instruction *> &Unhoistables); | |||
| 357 | ||||
| 358 | void classifyBiasedScopes(SmallVectorImpl<CHRScope *> &Scopes); | |||
| 359 | void classifyBiasedScopes(CHRScope *Scope, CHRScope *OutermostScope); | |||
| 360 | ||||
| 361 | void filterScopes(SmallVectorImpl<CHRScope *> &Input, | |||
| 362 | SmallVectorImpl<CHRScope *> &Output); | |||
| 363 | ||||
| 364 | void setCHRRegions(SmallVectorImpl<CHRScope *> &Input, | |||
| 365 | SmallVectorImpl<CHRScope *> &Output); | |||
| 366 | void setCHRRegions(CHRScope *Scope, CHRScope *OutermostScope); | |||
| 367 | ||||
| 368 | void sortScopes(SmallVectorImpl<CHRScope *> &Input, | |||
| 369 | SmallVectorImpl<CHRScope *> &Output); | |||
| 370 | ||||
| 371 | void transformScopes(SmallVectorImpl<CHRScope *> &CHRScopes); | |||
| 372 | void transformScopes(CHRScope *Scope, DenseSet<PHINode *> &TrivialPHIs); | |||
| 373 | void cloneScopeBlocks(CHRScope *Scope, | |||
| 374 | BasicBlock *PreEntryBlock, | |||
| 375 | BasicBlock *ExitBlock, | |||
| 376 | Region *LastRegion, | |||
| 377 | ValueToValueMapTy &VMap); | |||
| 378 | BranchInst *createMergedBranch(BasicBlock *PreEntryBlock, | |||
| 379 | BasicBlock *EntryBlock, | |||
| 380 | BasicBlock *NewEntryBlock, | |||
| 381 | ValueToValueMapTy &VMap); | |||
| 382 | void fixupBranchesAndSelects(CHRScope *Scope, | |||
| 383 | BasicBlock *PreEntryBlock, | |||
| 384 | BranchInst *MergedBR, | |||
| 385 | uint64_t ProfileCount); | |||
| 386 | void fixupBranch(Region *R, | |||
| 387 | CHRScope *Scope, | |||
| 388 | IRBuilder<> &IRB, | |||
| 389 | Value *&MergedCondition, BranchProbability &CHRBranchBias); | |||
| 390 | void fixupSelect(SelectInst* SI, | |||
| 391 | CHRScope *Scope, | |||
| 392 | IRBuilder<> &IRB, | |||
| 393 | Value *&MergedCondition, BranchProbability &CHRBranchBias); | |||
| 394 | void addToMergedCondition(bool IsTrueBiased, Value *Cond, | |||
| 395 | Instruction *BranchOrSelect, | |||
| 396 | CHRScope *Scope, | |||
| 397 | IRBuilder<> &IRB, | |||
| 398 | Value *&MergedCondition); | |||
| 399 | ||||
| 400 | Function &F; | |||
| 401 | BlockFrequencyInfo &BFI; | |||
| 402 | DominatorTree &DT; | |||
| 403 | ProfileSummaryInfo &PSI; | |||
| 404 | RegionInfo &RI; | |||
| 405 | OptimizationRemarkEmitter &ORE; | |||
| 406 | CHRStats Stats; | |||
| 407 | ||||
| 408 | // All the true-biased regions in the function | |||
| 409 | DenseSet<Region *> TrueBiasedRegionsGlobal; | |||
| 410 | // All the false-biased regions in the function | |||
| 411 | DenseSet<Region *> FalseBiasedRegionsGlobal; | |||
| 412 | // All the true-biased selects in the function | |||
| 413 | DenseSet<SelectInst *> TrueBiasedSelectsGlobal; | |||
| 414 | // All the false-biased selects in the function | |||
| 415 | DenseSet<SelectInst *> FalseBiasedSelectsGlobal; | |||
| 416 | // A map from biased regions to their branch bias | |||
| 417 | DenseMap<Region *, BranchProbability> BranchBiasMap; | |||
| 418 | // A map from biased selects to their branch bias | |||
| 419 | DenseMap<SelectInst *, BranchProbability> SelectBiasMap; | |||
| 420 | // All the scopes. | |||
| 421 | DenseSet<CHRScope *> Scopes; | |||
| 422 | }; | |||
| 423 | ||||
| 424 | } // end anonymous namespace | |||
| 425 | ||||
| 426 | static inline | |||
| 427 | raw_ostream LLVM_ATTRIBUTE_UNUSED__attribute__((__unused__)) &operator<<(raw_ostream &OS, | |||
| 428 | const CHRStats &Stats) { | |||
| 429 | Stats.print(OS); | |||
| 430 | return OS; | |||
| 431 | } | |||
| 432 | ||||
| 433 | static inline | |||
| 434 | raw_ostream &operator<<(raw_ostream &OS, const CHRScope &Scope) { | |||
| 435 | Scope.print(OS); | |||
| 436 | return OS; | |||
| 437 | } | |||
| 438 | ||||
| 439 | static bool shouldApply(Function &F, ProfileSummaryInfo& PSI) { | |||
| 440 | if (ForceCHR) | |||
| 441 | return true; | |||
| 442 | ||||
| 443 | if (!CHRModuleList.empty() || !CHRFunctionList.empty()) { | |||
| 444 | if (CHRModules.count(F.getParent()->getName())) | |||
| 445 | return true; | |||
| 446 | return CHRFunctions.count(F.getName()); | |||
| 447 | } | |||
| 448 | ||||
| 449 | assert(PSI.hasProfileSummary() && "Empty PSI?")((void)0); | |||
| 450 | return PSI.isFunctionEntryHot(&F); | |||
| 451 | } | |||
| 452 | ||||
| 453 | static void LLVM_ATTRIBUTE_UNUSED__attribute__((__unused__)) dumpIR(Function &F, const char *Label, | |||
| 454 | CHRStats *Stats) { | |||
| 455 | StringRef FuncName = F.getName(); | |||
| 456 | StringRef ModuleName = F.getParent()->getName(); | |||
| 457 | (void)(FuncName); // Unused in release build. | |||
| 458 | (void)(ModuleName); // Unused in release build. | |||
| 459 | CHR_DEBUG(dbgs() << "CHR IR dump " << Label << " " << ModuleName << " "do { } while (false) | |||
| 460 | << FuncName)do { } while (false); | |||
| 461 | if (Stats) | |||
| 462 | CHR_DEBUG(dbgs() << " " << *Stats)do { } while (false); | |||
| 463 | CHR_DEBUG(dbgs() << "\n")do { } while (false); | |||
| 464 | CHR_DEBUG(F.dump())do { } while (false); | |||
| 465 | } | |||
| 466 | ||||
| 467 | void CHRScope::print(raw_ostream &OS) const { | |||
| 468 | assert(RegInfos.size() > 0 && "Empty CHRScope")((void)0); | |||
| 469 | OS << "CHRScope["; | |||
| 470 | OS << RegInfos.size() << ", Regions["; | |||
| 471 | for (const RegInfo &RI : RegInfos) { | |||
| 472 | OS << RI.R->getNameStr(); | |||
| 473 | if (RI.HasBranch) | |||
| 474 | OS << " B"; | |||
| 475 | if (RI.Selects.size() > 0) | |||
| 476 | OS << " S" << RI.Selects.size(); | |||
| 477 | OS << ", "; | |||
| 478 | } | |||
| 479 | if (RegInfos[0].R->getParent()) { | |||
| 480 | OS << "], Parent " << RegInfos[0].R->getParent()->getNameStr(); | |||
| 481 | } else { | |||
| 482 | // top level region | |||
| 483 | OS << "]"; | |||
| 484 | } | |||
| 485 | OS << ", Subs["; | |||
| 486 | for (CHRScope *Sub : Subs) { | |||
| 487 | OS << *Sub << ", "; | |||
| 488 | } | |||
| 489 | OS << "]]"; | |||
| 490 | } | |||
| 491 | ||||
| 492 | // Return true if the given instruction type can be hoisted by CHR. | |||
| 493 | static bool isHoistableInstructionType(Instruction *I) { | |||
| 494 | return isa<BinaryOperator>(I) || isa<CastInst>(I) || isa<SelectInst>(I) || | |||
| 495 | isa<GetElementPtrInst>(I) || isa<CmpInst>(I) || | |||
| 496 | isa<InsertElementInst>(I) || isa<ExtractElementInst>(I) || | |||
| 497 | isa<ShuffleVectorInst>(I) || isa<ExtractValueInst>(I) || | |||
| 498 | isa<InsertValueInst>(I); | |||
| 499 | } | |||
| 500 | ||||
| 501 | // Return true if the given instruction can be hoisted by CHR. | |||
| 502 | static bool isHoistable(Instruction *I, DominatorTree &DT) { | |||
| 503 | if (!isHoistableInstructionType(I)) | |||
| 504 | return false; | |||
| 505 | return isSafeToSpeculativelyExecute(I, nullptr, &DT); | |||
| 506 | } | |||
| 507 | ||||
| 508 | // Recursively traverse the use-def chains of the given value and return a set | |||
| 509 | // of the unhoistable base values defined within the scope (excluding the | |||
| 510 | // first-region entry block) or the (hoistable or unhoistable) base values that | |||
| 511 | // are defined outside (including the first-region entry block) of the | |||
| 512 | // scope. The returned set doesn't include constants. | |||
| 513 | static const std::set<Value *> & | |||
| 514 | getBaseValues(Value *V, DominatorTree &DT, | |||
| 515 | DenseMap<Value *, std::set<Value *>> &Visited) { | |||
| 516 | auto It = Visited.find(V); | |||
| 517 | if (It != Visited.end()) { | |||
| 518 | return It->second; | |||
| 519 | } | |||
| 520 | std::set<Value *> Result; | |||
| 521 | if (auto *I = dyn_cast<Instruction>(V)) { | |||
| 522 | // We don't stop at a block that's not in the Scope because we would miss | |||
| 523 | // some instructions that are based on the same base values if we stop | |||
| 524 | // there. | |||
| 525 | if (!isHoistable(I, DT)) { | |||
| 526 | Result.insert(I); | |||
| 527 | return Visited.insert(std::make_pair(V, std::move(Result))).first->second; | |||
| 528 | } | |||
| 529 | // I is hoistable above the Scope. | |||
| 530 | for (Value *Op : I->operands()) { | |||
| 531 | const std::set<Value *> &OpResult = getBaseValues(Op, DT, Visited); | |||
| 532 | Result.insert(OpResult.begin(), OpResult.end()); | |||
| 533 | } | |||
| 534 | return Visited.insert(std::make_pair(V, std::move(Result))).first->second; | |||
| 535 | } | |||
| 536 | if (isa<Argument>(V)) { | |||
| 537 | Result.insert(V); | |||
| 538 | } | |||
| 539 | // We don't include others like constants because those won't lead to any | |||
| 540 | // chance of folding of conditions (eg two bit checks merged into one check) | |||
| 541 | // after CHR. | |||
| 542 | return Visited.insert(std::make_pair(V, std::move(Result))).first->second; | |||
| 543 | } | |||
| 544 | ||||
| 545 | // Return true if V is already hoisted or can be hoisted (along with its | |||
| 546 | // operands) above the insert point. When it returns true and HoistStops is | |||
| 547 | // non-null, the instructions to stop hoisting at through the use-def chains are | |||
| 548 | // inserted into HoistStops. | |||
| 549 | static bool | |||
| 550 | checkHoistValue(Value *V, Instruction *InsertPoint, DominatorTree &DT, | |||
| 551 | DenseSet<Instruction *> &Unhoistables, | |||
| 552 | DenseSet<Instruction *> *HoistStops, | |||
| 553 | DenseMap<Instruction *, bool> &Visited) { | |||
| 554 | assert(InsertPoint && "Null InsertPoint")((void)0); | |||
| 555 | if (auto *I = dyn_cast<Instruction>(V)) { | |||
| 556 | auto It = Visited.find(I); | |||
| 557 | if (It != Visited.end()) { | |||
| 558 | return It->second; | |||
| 559 | } | |||
| 560 | assert(DT.getNode(I->getParent()) && "DT must contain I's parent block")((void)0); | |||
| 561 | assert(DT.getNode(InsertPoint->getParent()) && "DT must contain Destination")((void)0); | |||
| 562 | if (Unhoistables.count(I)) { | |||
| 563 | // Don't hoist if they are not to be hoisted. | |||
| 564 | Visited[I] = false; | |||
| 565 | return false; | |||
| 566 | } | |||
| 567 | if (DT.dominates(I, InsertPoint)) { | |||
| 568 | // We are already above the insert point. Stop here. | |||
| 569 | if (HoistStops) | |||
| 570 | HoistStops->insert(I); | |||
| 571 | Visited[I] = true; | |||
| 572 | return true; | |||
| 573 | } | |||
| 574 | // We aren't not above the insert point, check if we can hoist it above the | |||
| 575 | // insert point. | |||
| 576 | if (isHoistable(I, DT)) { | |||
| 577 | // Check operands first. | |||
| 578 | DenseSet<Instruction *> OpsHoistStops; | |||
| 579 | bool AllOpsHoisted = true; | |||
| 580 | for (Value *Op : I->operands()) { | |||
| 581 | if (!checkHoistValue(Op, InsertPoint, DT, Unhoistables, &OpsHoistStops, | |||
| 582 | Visited)) { | |||
| 583 | AllOpsHoisted = false; | |||
| 584 | break; | |||
| 585 | } | |||
| 586 | } | |||
| 587 | if (AllOpsHoisted) { | |||
| 588 | CHR_DEBUG(dbgs() << "checkHoistValue " << *I << "\n")do { } while (false); | |||
| 589 | if (HoistStops) | |||
| 590 | HoistStops->insert(OpsHoistStops.begin(), OpsHoistStops.end()); | |||
| 591 | Visited[I] = true; | |||
| 592 | return true; | |||
| 593 | } | |||
| 594 | } | |||
| 595 | Visited[I] = false; | |||
| 596 | return false; | |||
| 597 | } | |||
| 598 | // Non-instructions are considered hoistable. | |||
| 599 | return true; | |||
| 600 | } | |||
| 601 | ||||
| 602 | // Returns true and sets the true probability and false probability of an | |||
| 603 | // MD_prof metadata if it's well-formed. | |||
| 604 | static bool checkMDProf(MDNode *MD, BranchProbability &TrueProb, | |||
| 605 | BranchProbability &FalseProb) { | |||
| 606 | if (!MD) return false; | |||
| 607 | MDString *MDName = cast<MDString>(MD->getOperand(0)); | |||
| 608 | if (MDName->getString() != "branch_weights" || | |||
| 609 | MD->getNumOperands() != 3) | |||
| 610 | return false; | |||
| 611 | ConstantInt *TrueWeight = mdconst::extract<ConstantInt>(MD->getOperand(1)); | |||
| 612 | ConstantInt *FalseWeight = mdconst::extract<ConstantInt>(MD->getOperand(2)); | |||
| 613 | if (!TrueWeight || !FalseWeight) | |||
| 614 | return false; | |||
| 615 | uint64_t TrueWt = TrueWeight->getValue().getZExtValue(); | |||
| 616 | uint64_t FalseWt = FalseWeight->getValue().getZExtValue(); | |||
| 617 | uint64_t SumWt = TrueWt + FalseWt; | |||
| 618 | ||||
| 619 | assert(SumWt >= TrueWt && SumWt >= FalseWt &&((void)0) | |||
| 620 | "Overflow calculating branch probabilities.")((void)0); | |||
| 621 | ||||
| 622 | // Guard against 0-to-0 branch weights to avoid a division-by-zero crash. | |||
| 623 | if (SumWt == 0) | |||
| 624 | return false; | |||
| 625 | ||||
| 626 | TrueProb = BranchProbability::getBranchProbability(TrueWt, SumWt); | |||
| 627 | FalseProb = BranchProbability::getBranchProbability(FalseWt, SumWt); | |||
| 628 | return true; | |||
| 629 | } | |||
| 630 | ||||
| 631 | static BranchProbability getCHRBiasThreshold() { | |||
| 632 | return BranchProbability::getBranchProbability( | |||
| 633 | static_cast<uint64_t>(CHRBiasThreshold * 1000000), 1000000); | |||
| 634 | } | |||
| 635 | ||||
| 636 | // A helper for CheckBiasedBranch and CheckBiasedSelect. If TrueProb >= | |||
| 637 | // CHRBiasThreshold, put Key into TrueSet and return true. If FalseProb >= | |||
| 638 | // CHRBiasThreshold, put Key into FalseSet and return true. Otherwise, return | |||
| 639 | // false. | |||
| 640 | template <typename K, typename S, typename M> | |||
| 641 | static bool checkBias(K *Key, BranchProbability TrueProb, | |||
| 642 | BranchProbability FalseProb, S &TrueSet, S &FalseSet, | |||
| 643 | M &BiasMap) { | |||
| 644 | BranchProbability Threshold = getCHRBiasThreshold(); | |||
| 645 | if (TrueProb >= Threshold) { | |||
| 646 | TrueSet.insert(Key); | |||
| 647 | BiasMap[Key] = TrueProb; | |||
| 648 | return true; | |||
| 649 | } else if (FalseProb >= Threshold) { | |||
| 650 | FalseSet.insert(Key); | |||
| 651 | BiasMap[Key] = FalseProb; | |||
| 652 | return true; | |||
| 653 | } | |||
| 654 | return false; | |||
| 655 | } | |||
| 656 | ||||
| 657 | // Returns true and insert a region into the right biased set and the map if the | |||
| 658 | // branch of the region is biased. | |||
| 659 | static bool checkBiasedBranch(BranchInst *BI, Region *R, | |||
| 660 | DenseSet<Region *> &TrueBiasedRegionsGlobal, | |||
| 661 | DenseSet<Region *> &FalseBiasedRegionsGlobal, | |||
| 662 | DenseMap<Region *, BranchProbability> &BranchBiasMap) { | |||
| 663 | if (!BI->isConditional()) | |||
| 664 | return false; | |||
| 665 | BranchProbability ThenProb, ElseProb; | |||
| 666 | if (!checkMDProf(BI->getMetadata(LLVMContext::MD_prof), | |||
| 667 | ThenProb, ElseProb)) | |||
| 668 | return false; | |||
| 669 | BasicBlock *IfThen = BI->getSuccessor(0); | |||
| 670 | BasicBlock *IfElse = BI->getSuccessor(1); | |||
| 671 | assert((IfThen == R->getExit() || IfElse == R->getExit()) &&((void)0) | |||
| 672 | IfThen != IfElse &&((void)0) | |||
| 673 | "Invariant from findScopes")((void)0); | |||
| 674 | if (IfThen == R->getExit()) { | |||
| 675 | // Swap them so that IfThen/ThenProb means going into the conditional code | |||
| 676 | // and IfElse/ElseProb means skipping it. | |||
| 677 | std::swap(IfThen, IfElse); | |||
| 678 | std::swap(ThenProb, ElseProb); | |||
| 679 | } | |||
| 680 | CHR_DEBUG(dbgs() << "BI " << *BI << " ")do { } while (false); | |||
| 681 | CHR_DEBUG(dbgs() << "ThenProb " << ThenProb << " ")do { } while (false); | |||
| 682 | CHR_DEBUG(dbgs() << "ElseProb " << ElseProb << "\n")do { } while (false); | |||
| 683 | return checkBias(R, ThenProb, ElseProb, | |||
| 684 | TrueBiasedRegionsGlobal, FalseBiasedRegionsGlobal, | |||
| 685 | BranchBiasMap); | |||
| 686 | } | |||
| 687 | ||||
| 688 | // Returns true and insert a select into the right biased set and the map if the | |||
| 689 | // select is biased. | |||
| 690 | static bool checkBiasedSelect( | |||
| 691 | SelectInst *SI, Region *R, | |||
| 692 | DenseSet<SelectInst *> &TrueBiasedSelectsGlobal, | |||
| 693 | DenseSet<SelectInst *> &FalseBiasedSelectsGlobal, | |||
| 694 | DenseMap<SelectInst *, BranchProbability> &SelectBiasMap) { | |||
| 695 | BranchProbability TrueProb, FalseProb; | |||
| 696 | if (!checkMDProf(SI->getMetadata(LLVMContext::MD_prof), | |||
| 697 | TrueProb, FalseProb)) | |||
| 698 | return false; | |||
| 699 | CHR_DEBUG(dbgs() << "SI " << *SI << " ")do { } while (false); | |||
| 700 | CHR_DEBUG(dbgs() << "TrueProb " << TrueProb << " ")do { } while (false); | |||
| 701 | CHR_DEBUG(dbgs() << "FalseProb " << FalseProb << "\n")do { } while (false); | |||
| 702 | return checkBias(SI, TrueProb, FalseProb, | |||
| 703 | TrueBiasedSelectsGlobal, FalseBiasedSelectsGlobal, | |||
| 704 | SelectBiasMap); | |||
| 705 | } | |||
| 706 | ||||
| 707 | // Returns the instruction at which to hoist the dependent condition values and | |||
| 708 | // insert the CHR branch for a region. This is the terminator branch in the | |||
| 709 | // entry block or the first select in the entry block, if any. | |||
| 710 | static Instruction* getBranchInsertPoint(RegInfo &RI) { | |||
| 711 | Region *R = RI.R; | |||
| 712 | BasicBlock *EntryBB = R->getEntry(); | |||
| 713 | // The hoist point is by default the terminator of the entry block, which is | |||
| 714 | // the same as the branch instruction if RI.HasBranch is true. | |||
| 715 | Instruction *HoistPoint = EntryBB->getTerminator(); | |||
| 716 | for (SelectInst *SI : RI.Selects) { | |||
| 717 | if (SI->getParent() == EntryBB) { | |||
| 718 | // Pick the first select in Selects in the entry block. Note Selects is | |||
| 719 | // sorted in the instruction order within a block (asserted below). | |||
| 720 | HoistPoint = SI; | |||
| 721 | break; | |||
| 722 | } | |||
| 723 | } | |||
| 724 | assert(HoistPoint && "Null HoistPoint")((void)0); | |||
| 725 | #ifndef NDEBUG1 | |||
| 726 | // Check that HoistPoint is the first one in Selects in the entry block, | |||
| 727 | // if any. | |||
| 728 | DenseSet<Instruction *> EntryBlockSelectSet; | |||
| 729 | for (SelectInst *SI : RI.Selects) { | |||
| 730 | if (SI->getParent() == EntryBB) { | |||
| 731 | EntryBlockSelectSet.insert(SI); | |||
| 732 | } | |||
| 733 | } | |||
| 734 | for (Instruction &I : *EntryBB) { | |||
| 735 | if (EntryBlockSelectSet.contains(&I)) { | |||
| 736 | assert(&I == HoistPoint &&((void)0) | |||
| 737 | "HoistPoint must be the first one in Selects")((void)0); | |||
| 738 | break; | |||
| 739 | } | |||
| 740 | } | |||
| 741 | #endif | |||
| 742 | return HoistPoint; | |||
| 743 | } | |||
| 744 | ||||
| 745 | // Find a CHR scope in the given region. | |||
| 746 | CHRScope * CHR::findScope(Region *R) { | |||
| 747 | CHRScope *Result = nullptr; | |||
| 748 | BasicBlock *Entry = R->getEntry(); | |||
| 749 | BasicBlock *Exit = R->getExit(); // null if top level. | |||
| 750 | assert(Entry && "Entry must not be null")((void)0); | |||
| 751 | assert((Exit == nullptr) == (R->isTopLevelRegion()) &&((void)0) | |||
| 752 | "Only top level region has a null exit")((void)0); | |||
| 753 | if (Entry) | |||
| 754 | CHR_DEBUG(dbgs() << "Entry " << Entry->getName() << "\n")do { } while (false); | |||
| 755 | else | |||
| 756 | CHR_DEBUG(dbgs() << "Entry null\n")do { } while (false); | |||
| 757 | if (Exit) | |||
| 758 | CHR_DEBUG(dbgs() << "Exit " << Exit->getName() << "\n")do { } while (false); | |||
| 759 | else | |||
| 760 | CHR_DEBUG(dbgs() << "Exit null\n")do { } while (false); | |||
| 761 | // Exclude cases where Entry is part of a subregion (hence it doesn't belong | |||
| 762 | // to this region). | |||
| 763 | bool EntryInSubregion = RI.getRegionFor(Entry) != R; | |||
| 764 | if (EntryInSubregion
| |||
| 765 | return nullptr; | |||
| 766 | // Exclude loops | |||
| 767 | for (BasicBlock *Pred : predecessors(Entry)) | |||
| 768 | if (R->contains(Pred)) | |||
| 769 | return nullptr; | |||
| 770 | // If any of the basic blocks have address taken, we must skip this region | |||
| 771 | // because we cannot clone basic blocks that have address taken. | |||
| 772 | for (BasicBlock *BB : R->blocks()) | |||
| 773 | if (BB->hasAddressTaken()) | |||
| 774 | return nullptr; | |||
| 775 | if (Exit
| |||
| 776 | // Try to find an if-then block (check if R is an if-then). | |||
| 777 | // if (cond) { | |||
| 778 | // ... | |||
| 779 | // } | |||
| 780 | auto *BI = dyn_cast<BranchInst>(Entry->getTerminator()); | |||
| ||||
| 781 | if (BI) | |||
| 782 | CHR_DEBUG(dbgs() << "BI.isConditional " << BI->isConditional() << "\n")do { } while (false); | |||
| 783 | else | |||
| 784 | CHR_DEBUG(dbgs() << "BI null\n")do { } while (false); | |||
| 785 | if (BI && BI->isConditional()) { | |||
| 786 | BasicBlock *S0 = BI->getSuccessor(0); | |||
| 787 | BasicBlock *S1 = BI->getSuccessor(1); | |||
| 788 | CHR_DEBUG(dbgs() << "S0 " << S0->getName() << "\n")do { } while (false); | |||
| 789 | CHR_DEBUG(dbgs() << "S1 " << S1->getName() << "\n")do { } while (false); | |||
| 790 | if (S0 != S1 && (S0 == Exit || S1 == Exit)) { | |||
| 791 | RegInfo RI(R); | |||
| 792 | RI.HasBranch = checkBiasedBranch( | |||
| 793 | BI, R, TrueBiasedRegionsGlobal, FalseBiasedRegionsGlobal, | |||
| 794 | BranchBiasMap); | |||
| 795 | Result = new CHRScope(RI); | |||
| 796 | Scopes.insert(Result); | |||
| 797 | CHR_DEBUG(dbgs() << "Found a region with a branch\n")do { } while (false); | |||
| 798 | ++Stats.NumBranches; | |||
| 799 | if (!RI.HasBranch) { | |||
| 800 | ORE.emit([&]() { | |||
| 801 | return OptimizationRemarkMissed(DEBUG_TYPE"chr", "BranchNotBiased", BI) | |||
| 802 | << "Branch not biased"; | |||
| 803 | }); | |||
| 804 | } | |||
| 805 | } | |||
| 806 | } | |||
| 807 | } | |||
| 808 | { | |||
| 809 | // Try to look for selects in the direct child blocks (as opposed to in | |||
| 810 | // subregions) of R. | |||
| 811 | // ... | |||
| 812 | // if (..) { // Some subregion | |||
| 813 | // ... | |||
| 814 | // } | |||
| 815 | // if (..) { // Some subregion | |||
| 816 | // ... | |||
| 817 | // } | |||
| 818 | // ... | |||
| 819 | // a = cond ? b : c; | |||
| 820 | // ... | |||
| 821 | SmallVector<SelectInst *, 8> Selects; | |||
| 822 | for (RegionNode *E : R->elements()) { | |||
| 823 | if (E->isSubRegion()) | |||
| 824 | continue; | |||
| 825 | // This returns the basic block of E if E is a direct child of R (not a | |||
| 826 | // subregion.) | |||
| 827 | BasicBlock *BB = E->getEntry(); | |||
| 828 | // Need to push in the order to make it easier to find the first Select | |||
| 829 | // later. | |||
| 830 | for (Instruction &I : *BB) { | |||
| 831 | if (auto *SI = dyn_cast<SelectInst>(&I)) { | |||
| 832 | Selects.push_back(SI); | |||
| 833 | ++Stats.NumBranches; | |||
| 834 | } | |||
| 835 | } | |||
| 836 | } | |||
| 837 | if (Selects.size() > 0) { | |||
| 838 | auto AddSelects = [&](RegInfo &RI) { | |||
| 839 | for (auto *SI : Selects) | |||
| 840 | if (checkBiasedSelect(SI, RI.R, | |||
| 841 | TrueBiasedSelectsGlobal, | |||
| 842 | FalseBiasedSelectsGlobal, | |||
| 843 | SelectBiasMap)) | |||
| 844 | RI.Selects.push_back(SI); | |||
| 845 | else | |||
| 846 | ORE.emit([&]() { | |||
| 847 | return OptimizationRemarkMissed(DEBUG_TYPE"chr", "SelectNotBiased", SI) | |||
| 848 | << "Select not biased"; | |||
| 849 | }); | |||
| 850 | }; | |||
| 851 | if (!Result) { | |||
| 852 | CHR_DEBUG(dbgs() << "Found a select-only region\n")do { } while (false); | |||
| 853 | RegInfo RI(R); | |||
| 854 | AddSelects(RI); | |||
| 855 | Result = new CHRScope(RI); | |||
| 856 | Scopes.insert(Result); | |||
| 857 | } else { | |||
| 858 | CHR_DEBUG(dbgs() << "Found select(s) in a region with a branch\n")do { } while (false); | |||
| 859 | AddSelects(Result->RegInfos[0]); | |||
| 860 | } | |||
| 861 | } | |||
| 862 | } | |||
| 863 | ||||
| 864 | if (Result) { | |||
| 865 | checkScopeHoistable(Result); | |||
| 866 | } | |||
| 867 | return Result; | |||
| 868 | } | |||
| 869 | ||||
| 870 | // Check that any of the branch and the selects in the region could be | |||
| 871 | // hoisted above the the CHR branch insert point (the most dominating of | |||
| 872 | // them, either the branch (at the end of the first block) or the first | |||
| 873 | // select in the first block). If the branch can't be hoisted, drop the | |||
| 874 | // selects in the first blocks. | |||
| 875 | // | |||
| 876 | // For example, for the following scope/region with selects, we want to insert | |||
| 877 | // the merged branch right before the first select in the first/entry block by | |||
| 878 | // hoisting c1, c2, c3, and c4. | |||
| 879 | // | |||
| 880 | // // Branch insert point here. | |||
| 881 | // a = c1 ? b : c; // Select 1 | |||
| 882 | // d = c2 ? e : f; // Select 2 | |||
| 883 | // if (c3) { // Branch | |||
| 884 | // ... | |||
| 885 | // c4 = foo() // A call. | |||
| 886 | // g = c4 ? h : i; // Select 3 | |||
| 887 | // } | |||
| 888 | // | |||
| 889 | // But suppose we can't hoist c4 because it's dependent on the preceding | |||
| 890 | // call. Then, we drop Select 3. Furthermore, if we can't hoist c2, we also drop | |||
| 891 | // Select 2. If we can't hoist c3, we drop Selects 1 & 2. | |||
| 892 | void CHR::checkScopeHoistable(CHRScope *Scope) { | |||
| 893 | RegInfo &RI = Scope->RegInfos[0]; | |||
| 894 | Region *R = RI.R; | |||
| 895 | BasicBlock *EntryBB = R->getEntry(); | |||
| 896 | auto *Branch = RI.HasBranch ? | |||
| 897 | cast<BranchInst>(EntryBB->getTerminator()) : nullptr; | |||
| 898 | SmallVector<SelectInst *, 8> &Selects = RI.Selects; | |||
| 899 | if (RI.HasBranch || !Selects.empty()) { | |||
| 900 | Instruction *InsertPoint = getBranchInsertPoint(RI); | |||
| 901 | CHR_DEBUG(dbgs() << "InsertPoint " << *InsertPoint << "\n")do { } while (false); | |||
| 902 | // Avoid a data dependence from a select or a branch to a(nother) | |||
| 903 | // select. Note no instruction can't data-depend on a branch (a branch | |||
| 904 | // instruction doesn't produce a value). | |||
| 905 | DenseSet<Instruction *> Unhoistables; | |||
| 906 | // Initialize Unhoistables with the selects. | |||
| 907 | for (SelectInst *SI : Selects) { | |||
| 908 | Unhoistables.insert(SI); | |||
| 909 | } | |||
| 910 | // Remove Selects that can't be hoisted. | |||
| 911 | for (auto it = Selects.begin(); it != Selects.end(); ) { | |||
| 912 | SelectInst *SI = *it; | |||
| 913 | if (SI == InsertPoint) { | |||
| 914 | ++it; | |||
| 915 | continue; | |||
| 916 | } | |||
| 917 | DenseMap<Instruction *, bool> Visited; | |||
| 918 | bool IsHoistable = checkHoistValue(SI->getCondition(), InsertPoint, | |||
| 919 | DT, Unhoistables, nullptr, Visited); | |||
| 920 | if (!IsHoistable) { | |||
| 921 | CHR_DEBUG(dbgs() << "Dropping select " << *SI << "\n")do { } while (false); | |||
| 922 | ORE.emit([&]() { | |||
| 923 | return OptimizationRemarkMissed(DEBUG_TYPE"chr", | |||
| 924 | "DropUnhoistableSelect", SI) | |||
| 925 | << "Dropped unhoistable select"; | |||
| 926 | }); | |||
| 927 | it = Selects.erase(it); | |||
| 928 | // Since we are dropping the select here, we also drop it from | |||
| 929 | // Unhoistables. | |||
| 930 | Unhoistables.erase(SI); | |||
| 931 | } else | |||
| 932 | ++it; | |||
| 933 | } | |||
| 934 | // Update InsertPoint after potentially removing selects. | |||
| 935 | InsertPoint = getBranchInsertPoint(RI); | |||
| 936 | CHR_DEBUG(dbgs() << "InsertPoint " << *InsertPoint << "\n")do { } while (false); | |||
| 937 | if (RI.HasBranch && InsertPoint != Branch) { | |||
| 938 | DenseMap<Instruction *, bool> Visited; | |||
| 939 | bool IsHoistable = checkHoistValue(Branch->getCondition(), InsertPoint, | |||
| 940 | DT, Unhoistables, nullptr, Visited); | |||
| 941 | if (!IsHoistable) { | |||
| 942 | // If the branch isn't hoistable, drop the selects in the entry | |||
| 943 | // block, preferring the branch, which makes the branch the hoist | |||
| 944 | // point. | |||
| 945 | assert(InsertPoint != Branch && "Branch must not be the hoist point")((void)0); | |||
| 946 | CHR_DEBUG(dbgs() << "Dropping selects in entry block \n")do { } while (false); | |||
| 947 | CHR_DEBUG(do { } while (false) | |||
| 948 | for (SelectInst *SI : Selects) {do { } while (false) | |||
| 949 | dbgs() << "SI " << *SI << "\n";do { } while (false) | |||
| 950 | })do { } while (false); | |||
| 951 | for (SelectInst *SI : Selects) { | |||
| 952 | ORE.emit([&]() { | |||
| 953 | return OptimizationRemarkMissed(DEBUG_TYPE"chr", | |||
| 954 | "DropSelectUnhoistableBranch", SI) | |||
| 955 | << "Dropped select due to unhoistable branch"; | |||
| 956 | }); | |||
| 957 | } | |||
| 958 | llvm::erase_if(Selects, [EntryBB](SelectInst *SI) { | |||
| 959 | return SI->getParent() == EntryBB; | |||
| 960 | }); | |||
| 961 | Unhoistables.clear(); | |||
| 962 | InsertPoint = Branch; | |||
| 963 | } | |||
| 964 | } | |||
| 965 | CHR_DEBUG(dbgs() << "InsertPoint " << *InsertPoint << "\n")do { } while (false); | |||
| 966 | #ifndef NDEBUG1 | |||
| 967 | if (RI.HasBranch) { | |||
| 968 | assert(!DT.dominates(Branch, InsertPoint) &&((void)0) | |||
| 969 | "Branch can't be already above the hoist point")((void)0); | |||
| 970 | DenseMap<Instruction *, bool> Visited; | |||
| 971 | assert(checkHoistValue(Branch->getCondition(), InsertPoint,((void)0) | |||
| 972 | DT, Unhoistables, nullptr, Visited) &&((void)0) | |||
| 973 | "checkHoistValue for branch")((void)0); | |||
| 974 | } | |||
| 975 | for (auto *SI : Selects) { | |||
| 976 | assert(!DT.dominates(SI, InsertPoint) &&((void)0) | |||
| 977 | "SI can't be already above the hoist point")((void)0); | |||
| 978 | DenseMap<Instruction *, bool> Visited; | |||
| 979 | assert(checkHoistValue(SI->getCondition(), InsertPoint, DT,((void)0) | |||
| 980 | Unhoistables, nullptr, Visited) &&((void)0) | |||
| 981 | "checkHoistValue for selects")((void)0); | |||
| 982 | } | |||
| 983 | CHR_DEBUG(dbgs() << "Result\n")do { } while (false); | |||
| 984 | if (RI.HasBranch) { | |||
| 985 | CHR_DEBUG(dbgs() << "BI " << *Branch << "\n")do { } while (false); | |||
| 986 | } | |||
| 987 | for (auto *SI : Selects) { | |||
| 988 | CHR_DEBUG(dbgs() << "SI " << *SI << "\n")do { } while (false); | |||
| 989 | } | |||
| 990 | #endif | |||
| 991 | } | |||
| 992 | } | |||
| 993 | ||||
| 994 | // Traverse the region tree, find all nested scopes and merge them if possible. | |||
| 995 | CHRScope * CHR::findScopes(Region *R, Region *NextRegion, Region *ParentRegion, | |||
| 996 | SmallVectorImpl<CHRScope *> &Scopes) { | |||
| 997 | CHR_DEBUG(dbgs() << "findScopes " << R->getNameStr() << "\n")do { } while (false); | |||
| 998 | CHRScope *Result = findScope(R); | |||
| 999 | // Visit subscopes. | |||
| 1000 | CHRScope *ConsecutiveSubscope = nullptr; | |||
| 1001 | SmallVector<CHRScope *, 8> Subscopes; | |||
| 1002 | for (auto It = R->begin(); It != R->end(); ++It) { | |||
| 1003 | const std::unique_ptr<Region> &SubR = *It; | |||
| 1004 | auto NextIt = std::next(It); | |||
| 1005 | Region *NextSubR = NextIt != R->end() ? NextIt->get() : nullptr; | |||
| 1006 | CHR_DEBUG(dbgs() << "Looking at subregion " << SubR.get()->getNameStr()do { } while (false) | |||
| 1007 | << "\n")do { } while (false); | |||
| 1008 | CHRScope *SubCHRScope = findScopes(SubR.get(), NextSubR, R, Scopes); | |||
| 1009 | if (SubCHRScope) { | |||
| 1010 | CHR_DEBUG(dbgs() << "Subregion Scope " << *SubCHRScope << "\n")do { } while (false); | |||
| 1011 | } else { | |||
| 1012 | CHR_DEBUG(dbgs() << "Subregion Scope null\n")do { } while (false); | |||
| 1013 | } | |||
| 1014 | if (SubCHRScope) { | |||
| 1015 | if (!ConsecutiveSubscope) | |||
| 1016 | ConsecutiveSubscope = SubCHRScope; | |||
| 1017 | else if (!ConsecutiveSubscope->appendable(SubCHRScope)) { | |||
| 1018 | Subscopes.push_back(ConsecutiveSubscope); | |||
| 1019 | ConsecutiveSubscope = SubCHRScope; | |||
| 1020 | } else | |||
| 1021 | ConsecutiveSubscope->append(SubCHRScope); | |||
| 1022 | } else { | |||
| 1023 | if (ConsecutiveSubscope) { | |||
| 1024 | Subscopes.push_back(ConsecutiveSubscope); | |||
| 1025 | } | |||
| 1026 | ConsecutiveSubscope = nullptr; | |||
| 1027 | } | |||
| 1028 | } | |||
| 1029 | if (ConsecutiveSubscope) { | |||
| 1030 | Subscopes.push_back(ConsecutiveSubscope); | |||
| 1031 | } | |||
| 1032 | for (CHRScope *Sub : Subscopes) { | |||
| 1033 | if (Result) { | |||
| 1034 | // Combine it with the parent. | |||
| 1035 | Result->addSub(Sub); | |||
| 1036 | } else { | |||
| 1037 | // Push Subscopes as they won't be combined with the parent. | |||
| 1038 | Scopes.push_back(Sub); | |||
| 1039 | } | |||
| 1040 | } | |||
| 1041 | return Result; | |||
| 1042 | } | |||
| 1043 | ||||
| 1044 | static DenseSet<Value *> getCHRConditionValuesForRegion(RegInfo &RI) { | |||
| 1045 | DenseSet<Value *> ConditionValues; | |||
| 1046 | if (RI.HasBranch) { | |||
| 1047 | auto *BI = cast<BranchInst>(RI.R->getEntry()->getTerminator()); | |||
| 1048 | ConditionValues.insert(BI->getCondition()); | |||
| 1049 | } | |||
| 1050 | for (SelectInst *SI : RI.Selects) { | |||
| 1051 | ConditionValues.insert(SI->getCondition()); | |||
| 1052 | } | |||
| 1053 | return ConditionValues; | |||
| 1054 | } | |||
| 1055 | ||||
| 1056 | ||||
| 1057 | // Determine whether to split a scope depending on the sets of the branch | |||
| 1058 | // condition values of the previous region and the current region. We split | |||
| 1059 | // (return true) it if 1) the condition values of the inner/lower scope can't be | |||
| 1060 | // hoisted up to the outer/upper scope, or 2) the two sets of the condition | |||
| 1061 | // values have an empty intersection (because the combined branch conditions | |||
| 1062 | // won't probably lead to a simpler combined condition). | |||
| 1063 | static bool shouldSplit(Instruction *InsertPoint, | |||
| 1064 | DenseSet<Value *> &PrevConditionValues, | |||
| 1065 | DenseSet<Value *> &ConditionValues, | |||
| 1066 | DominatorTree &DT, | |||
| 1067 | DenseSet<Instruction *> &Unhoistables) { | |||
| 1068 | assert(InsertPoint && "Null InsertPoint")((void)0); | |||
| 1069 | CHR_DEBUG(do { } while (false) | |||
| 1070 | dbgs() << "shouldSplit " << *InsertPoint << " PrevConditionValues ";do { } while (false) | |||
| 1071 | for (Value *V : PrevConditionValues) {do { } while (false) | |||
| 1072 | dbgs() << *V << ", ";do { } while (false) | |||
| 1073 | }do { } while (false) | |||
| 1074 | dbgs() << " ConditionValues ";do { } while (false) | |||
| 1075 | for (Value *V : ConditionValues) {do { } while (false) | |||
| 1076 | dbgs() << *V << ", ";do { } while (false) | |||
| 1077 | }do { } while (false) | |||
| 1078 | dbgs() << "\n")do { } while (false); | |||
| 1079 | // If any of Bases isn't hoistable to the hoist point, split. | |||
| 1080 | for (Value *V : ConditionValues) { | |||
| 1081 | DenseMap<Instruction *, bool> Visited; | |||
| 1082 | if (!checkHoistValue(V, InsertPoint, DT, Unhoistables, nullptr, Visited)) { | |||
| 1083 | CHR_DEBUG(dbgs() << "Split. checkHoistValue false " << *V << "\n")do { } while (false); | |||
| 1084 | return true; // Not hoistable, split. | |||
| 1085 | } | |||
| 1086 | } | |||
| 1087 | // If PrevConditionValues or ConditionValues is empty, don't split to avoid | |||
| 1088 | // unnecessary splits at scopes with no branch/selects. If | |||
| 1089 | // PrevConditionValues and ConditionValues don't intersect at all, split. | |||
| 1090 | if (!PrevConditionValues.empty() && !ConditionValues.empty()) { | |||
| 1091 | // Use std::set as DenseSet doesn't work with set_intersection. | |||
| 1092 | std::set<Value *> PrevBases, Bases; | |||
| 1093 | DenseMap<Value *, std::set<Value *>> Visited; | |||
| 1094 | for (Value *V : PrevConditionValues) { | |||
| 1095 | const std::set<Value *> &BaseValues = getBaseValues(V, DT, Visited); | |||
| 1096 | PrevBases.insert(BaseValues.begin(), BaseValues.end()); | |||
| 1097 | } | |||
| 1098 | for (Value *V : ConditionValues) { | |||
| 1099 | const std::set<Value *> &BaseValues = getBaseValues(V, DT, Visited); | |||
| 1100 | Bases.insert(BaseValues.begin(), BaseValues.end()); | |||
| 1101 | } | |||
| 1102 | CHR_DEBUG(do { } while (false) | |||
| 1103 | dbgs() << "PrevBases ";do { } while (false) | |||
| 1104 | for (Value *V : PrevBases) {do { } while (false) | |||
| 1105 | dbgs() << *V << ", ";do { } while (false) | |||
| 1106 | }do { } while (false) | |||
| 1107 | dbgs() << " Bases ";do { } while (false) | |||
| 1108 | for (Value *V : Bases) {do { } while (false) | |||
| 1109 | dbgs() << *V << ", ";do { } while (false) | |||
| 1110 | }do { } while (false) | |||
| 1111 | dbgs() << "\n")do { } while (false); | |||
| 1112 | std::vector<Value *> Intersection; | |||
| 1113 | std::set_intersection(PrevBases.begin(), PrevBases.end(), Bases.begin(), | |||
| 1114 | Bases.end(), std::back_inserter(Intersection)); | |||
| 1115 | if (Intersection.empty()) { | |||
| 1116 | // Empty intersection, split. | |||
| 1117 | CHR_DEBUG(dbgs() << "Split. Intersection empty\n")do { } while (false); | |||
| 1118 | return true; | |||
| 1119 | } | |||
| 1120 | } | |||
| 1121 | CHR_DEBUG(dbgs() << "No split\n")do { } while (false); | |||
| 1122 | return false; // Don't split. | |||
| 1123 | } | |||
| 1124 | ||||
| 1125 | static void getSelectsInScope(CHRScope *Scope, | |||
| 1126 | DenseSet<Instruction *> &Output) { | |||
| 1127 | for (RegInfo &RI : Scope->RegInfos) | |||
| 1128 | for (SelectInst *SI : RI.Selects) | |||
| 1129 | Output.insert(SI); | |||
| 1130 | for (CHRScope *Sub : Scope->Subs) | |||
| 1131 | getSelectsInScope(Sub, Output); | |||
| 1132 | } | |||
| 1133 | ||||
| 1134 | void CHR::splitScopes(SmallVectorImpl<CHRScope *> &Input, | |||
| 1135 | SmallVectorImpl<CHRScope *> &Output) { | |||
| 1136 | for (CHRScope *Scope : Input) { | |||
| 1137 | assert(!Scope->BranchInsertPoint &&((void)0) | |||
| 1138 | "BranchInsertPoint must not be set")((void)0); | |||
| 1139 | DenseSet<Instruction *> Unhoistables; | |||
| 1140 | getSelectsInScope(Scope, Unhoistables); | |||
| 1141 | splitScope(Scope, nullptr, nullptr, nullptr, Output, Unhoistables); | |||
| 1142 | } | |||
| 1143 | #ifndef NDEBUG1 | |||
| 1144 | for (CHRScope *Scope : Output) { | |||
| 1145 | assert(Scope->BranchInsertPoint && "BranchInsertPoint must be set")((void)0); | |||
| 1146 | } | |||
| 1147 | #endif | |||
| 1148 | } | |||
| 1149 | ||||
| 1150 | SmallVector<CHRScope *, 8> CHR::splitScope( | |||
| 1151 | CHRScope *Scope, | |||
| 1152 | CHRScope *Outer, | |||
| 1153 | DenseSet<Value *> *OuterConditionValues, | |||
| 1154 | Instruction *OuterInsertPoint, | |||
| 1155 | SmallVectorImpl<CHRScope *> &Output, | |||
| 1156 | DenseSet<Instruction *> &Unhoistables) { | |||
| 1157 | if (Outer) { | |||
| 1158 | assert(OuterConditionValues && "Null OuterConditionValues")((void)0); | |||
| 1159 | assert(OuterInsertPoint && "Null OuterInsertPoint")((void)0); | |||
| 1160 | } | |||
| 1161 | bool PrevSplitFromOuter = true; | |||
| 1162 | DenseSet<Value *> PrevConditionValues; | |||
| 1163 | Instruction *PrevInsertPoint = nullptr; | |||
| 1164 | SmallVector<CHRScope *, 8> Splits; | |||
| 1165 | SmallVector<bool, 8> SplitsSplitFromOuter; | |||
| 1166 | SmallVector<DenseSet<Value *>, 8> SplitsConditionValues; | |||
| 1167 | SmallVector<Instruction *, 8> SplitsInsertPoints; | |||
| 1168 | SmallVector<RegInfo, 8> RegInfos(Scope->RegInfos); // Copy | |||
| 1169 | for (RegInfo &RI : RegInfos) { | |||
| 1170 | Instruction *InsertPoint = getBranchInsertPoint(RI); | |||
| 1171 | DenseSet<Value *> ConditionValues = getCHRConditionValuesForRegion(RI); | |||
| 1172 | CHR_DEBUG(do { } while (false) | |||
| 1173 | dbgs() << "ConditionValues ";do { } while (false) | |||
| 1174 | for (Value *V : ConditionValues) {do { } while (false) | |||
| 1175 | dbgs() << *V << ", ";do { } while (false) | |||
| 1176 | }do { } while (false) | |||
| 1177 | dbgs() << "\n")do { } while (false); | |||
| 1178 | if (RI.R == RegInfos[0].R) { | |||
| 1179 | // First iteration. Check to see if we should split from the outer. | |||
| 1180 | if (Outer) { | |||
| 1181 | CHR_DEBUG(dbgs() << "Outer " << *Outer << "\n")do { } while (false); | |||
| 1182 | CHR_DEBUG(dbgs() << "Should split from outer at "do { } while (false) | |||
| 1183 | << RI.R->getNameStr() << "\n")do { } while (false); | |||
| 1184 | if (shouldSplit(OuterInsertPoint, *OuterConditionValues, | |||
| 1185 | ConditionValues, DT, Unhoistables)) { | |||
| 1186 | PrevConditionValues = ConditionValues; | |||
| 1187 | PrevInsertPoint = InsertPoint; | |||
| 1188 | ORE.emit([&]() { | |||
| 1189 | return OptimizationRemarkMissed(DEBUG_TYPE"chr", | |||
| 1190 | "SplitScopeFromOuter", | |||
| 1191 | RI.R->getEntry()->getTerminator()) | |||
| 1192 | << "Split scope from outer due to unhoistable branch/select " | |||
| 1193 | << "and/or lack of common condition values"; | |||
| 1194 | }); | |||
| 1195 | } else { | |||
| 1196 | // Not splitting from the outer. Use the outer bases and insert | |||
| 1197 | // point. Union the bases. | |||
| 1198 | PrevSplitFromOuter = false; | |||
| 1199 | PrevConditionValues = *OuterConditionValues; | |||
| 1200 | PrevConditionValues.insert(ConditionValues.begin(), | |||
| 1201 | ConditionValues.end()); | |||
| 1202 | PrevInsertPoint = OuterInsertPoint; | |||
| 1203 | } | |||
| 1204 | } else { | |||
| 1205 | CHR_DEBUG(dbgs() << "Outer null\n")do { } while (false); | |||
| 1206 | PrevConditionValues = ConditionValues; | |||
| 1207 | PrevInsertPoint = InsertPoint; | |||
| 1208 | } | |||
| 1209 | } else { | |||
| 1210 | CHR_DEBUG(dbgs() << "Should split from prev at "do { } while (false) | |||
| 1211 | << RI.R->getNameStr() << "\n")do { } while (false); | |||
| 1212 | if (shouldSplit(PrevInsertPoint, PrevConditionValues, ConditionValues, | |||
| 1213 | DT, Unhoistables)) { | |||
| 1214 | CHRScope *Tail = Scope->split(RI.R); | |||
| 1215 | Scopes.insert(Tail); | |||
| 1216 | Splits.push_back(Scope); | |||
| 1217 | SplitsSplitFromOuter.push_back(PrevSplitFromOuter); | |||
| 1218 | SplitsConditionValues.push_back(PrevConditionValues); | |||
| 1219 | SplitsInsertPoints.push_back(PrevInsertPoint); | |||
| 1220 | Scope = Tail; | |||
| 1221 | PrevConditionValues = ConditionValues; | |||
| 1222 | PrevInsertPoint = InsertPoint; | |||
| 1223 | PrevSplitFromOuter = true; | |||
| 1224 | ORE.emit([&]() { | |||
| 1225 | return OptimizationRemarkMissed(DEBUG_TYPE"chr", | |||
| 1226 | "SplitScopeFromPrev", | |||
| 1227 | RI.R->getEntry()->getTerminator()) | |||
| 1228 | << "Split scope from previous due to unhoistable branch/select " | |||
| 1229 | << "and/or lack of common condition values"; | |||
| 1230 | }); | |||
| 1231 | } else { | |||
| 1232 | // Not splitting. Union the bases. Keep the hoist point. | |||
| 1233 | PrevConditionValues.insert(ConditionValues.begin(), ConditionValues.end()); | |||
| 1234 | } | |||
| 1235 | } | |||
| 1236 | } | |||
| 1237 | Splits.push_back(Scope); | |||
| 1238 | SplitsSplitFromOuter.push_back(PrevSplitFromOuter); | |||
| 1239 | SplitsConditionValues.push_back(PrevConditionValues); | |||
| 1240 | assert(PrevInsertPoint && "Null PrevInsertPoint")((void)0); | |||
| 1241 | SplitsInsertPoints.push_back(PrevInsertPoint); | |||
| 1242 | assert(Splits.size() == SplitsConditionValues.size() &&((void)0) | |||
| 1243 | Splits.size() == SplitsSplitFromOuter.size() &&((void)0) | |||
| 1244 | Splits.size() == SplitsInsertPoints.size() && "Mismatching sizes")((void)0); | |||
| 1245 | for (size_t I = 0; I < Splits.size(); ++I) { | |||
| 1246 | CHRScope *Split = Splits[I]; | |||
| 1247 | DenseSet<Value *> &SplitConditionValues = SplitsConditionValues[I]; | |||
| 1248 | Instruction *SplitInsertPoint = SplitsInsertPoints[I]; | |||
| 1249 | SmallVector<CHRScope *, 8> NewSubs; | |||
| 1250 | DenseSet<Instruction *> SplitUnhoistables; | |||
| 1251 | getSelectsInScope(Split, SplitUnhoistables); | |||
| 1252 | for (CHRScope *Sub : Split->Subs) { | |||
| 1253 | SmallVector<CHRScope *, 8> SubSplits = splitScope( | |||
| 1254 | Sub, Split, &SplitConditionValues, SplitInsertPoint, Output, | |||
| 1255 | SplitUnhoistables); | |||
| 1256 | llvm::append_range(NewSubs, SubSplits); | |||
| 1257 | } | |||
| 1258 | Split->Subs = NewSubs; | |||
| 1259 | } | |||
| 1260 | SmallVector<CHRScope *, 8> Result; | |||
| 1261 | for (size_t I = 0; I < Splits.size(); ++I) { | |||
| 1262 | CHRScope *Split = Splits[I]; | |||
| 1263 | if (SplitsSplitFromOuter[I]) { | |||
| 1264 | // Split from the outer. | |||
| 1265 | Output.push_back(Split); | |||
| 1266 | Split->BranchInsertPoint = SplitsInsertPoints[I]; | |||
| 1267 | CHR_DEBUG(dbgs() << "BranchInsertPoint " << *SplitsInsertPoints[I]do { } while (false) | |||
| 1268 | << "\n")do { } while (false); | |||
| 1269 | } else { | |||
| 1270 | // Connected to the outer. | |||
| 1271 | Result.push_back(Split); | |||
| 1272 | } | |||
| 1273 | } | |||
| 1274 | if (!Outer) | |||
| 1275 | assert(Result.empty() &&((void)0) | |||
| 1276 | "If no outer (top-level), must return no nested ones")((void)0); | |||
| 1277 | return Result; | |||
| 1278 | } | |||
| 1279 | ||||
| 1280 | void CHR::classifyBiasedScopes(SmallVectorImpl<CHRScope *> &Scopes) { | |||
| 1281 | for (CHRScope *Scope : Scopes) { | |||
| 1282 | assert(Scope->TrueBiasedRegions.empty() && Scope->FalseBiasedRegions.empty() && "Empty")((void)0); | |||
| 1283 | classifyBiasedScopes(Scope, Scope); | |||
| 1284 | CHR_DEBUG(do { } while (false) | |||
| 1285 | dbgs() << "classifyBiasedScopes " << *Scope << "\n";do { } while (false) | |||
| 1286 | dbgs() << "TrueBiasedRegions ";do { } while (false) | |||
| 1287 | for (Region *R : Scope->TrueBiasedRegions) {do { } while (false) | |||
| 1288 | dbgs() << R->getNameStr() << ", ";do { } while (false) | |||
| 1289 | }do { } while (false) | |||
| 1290 | dbgs() << "\n";do { } while (false) | |||
| 1291 | dbgs() << "FalseBiasedRegions ";do { } while (false) | |||
| 1292 | for (Region *R : Scope->FalseBiasedRegions) {do { } while (false) | |||
| 1293 | dbgs() << R->getNameStr() << ", ";do { } while (false) | |||
| 1294 | }do { } while (false) | |||
| 1295 | dbgs() << "\n";do { } while (false) | |||
| 1296 | dbgs() << "TrueBiasedSelects ";do { } while (false) | |||
| 1297 | for (SelectInst *SI : Scope->TrueBiasedSelects) {do { } while (false) | |||
| 1298 | dbgs() << *SI << ", ";do { } while (false) | |||
| 1299 | }do { } while (false) | |||
| 1300 | dbgs() << "\n";do { } while (false) | |||
| 1301 | dbgs() << "FalseBiasedSelects ";do { } while (false) | |||
| 1302 | for (SelectInst *SI : Scope->FalseBiasedSelects) {do { } while (false) | |||
| 1303 | dbgs() << *SI << ", ";do { } while (false) | |||
| 1304 | }do { } while (false) | |||
| 1305 | dbgs() << "\n";)do { } while (false); | |||
| 1306 | } | |||
| 1307 | } | |||
| 1308 | ||||
| 1309 | void CHR::classifyBiasedScopes(CHRScope *Scope, CHRScope *OutermostScope) { | |||
| 1310 | for (RegInfo &RI : Scope->RegInfos) { | |||
| 1311 | if (RI.HasBranch) { | |||
| 1312 | Region *R = RI.R; | |||
| 1313 | if (TrueBiasedRegionsGlobal.contains(R)) | |||
| 1314 | OutermostScope->TrueBiasedRegions.insert(R); | |||
| 1315 | else if (FalseBiasedRegionsGlobal.contains(R)) | |||
| 1316 | OutermostScope->FalseBiasedRegions.insert(R); | |||
| 1317 | else | |||
| 1318 | llvm_unreachable("Must be biased")__builtin_unreachable(); | |||
| 1319 | } | |||
| 1320 | for (SelectInst *SI : RI.Selects) { | |||
| 1321 | if (TrueBiasedSelectsGlobal.contains(SI)) | |||
| 1322 | OutermostScope->TrueBiasedSelects.insert(SI); | |||
| 1323 | else if (FalseBiasedSelectsGlobal.contains(SI)) | |||
| 1324 | OutermostScope->FalseBiasedSelects.insert(SI); | |||
| 1325 | else | |||
| 1326 | llvm_unreachable("Must be biased")__builtin_unreachable(); | |||
| 1327 | } | |||
| 1328 | } | |||
| 1329 | for (CHRScope *Sub : Scope->Subs) { | |||
| 1330 | classifyBiasedScopes(Sub, OutermostScope); | |||
| 1331 | } | |||
| 1332 | } | |||
| 1333 | ||||
| 1334 | static bool hasAtLeastTwoBiasedBranches(CHRScope *Scope) { | |||
| 1335 | unsigned NumBiased = Scope->TrueBiasedRegions.size() + | |||
| 1336 | Scope->FalseBiasedRegions.size() + | |||
| 1337 | Scope->TrueBiasedSelects.size() + | |||
| 1338 | Scope->FalseBiasedSelects.size(); | |||
| 1339 | return NumBiased >= CHRMergeThreshold; | |||
| 1340 | } | |||
| 1341 | ||||
| 1342 | void CHR::filterScopes(SmallVectorImpl<CHRScope *> &Input, | |||
| 1343 | SmallVectorImpl<CHRScope *> &Output) { | |||
| 1344 | for (CHRScope *Scope : Input) { | |||
| 1345 | // Filter out the ones with only one region and no subs. | |||
| 1346 | if (!hasAtLeastTwoBiasedBranches(Scope)) { | |||
| 1347 | CHR_DEBUG(dbgs() << "Filtered out by biased branches truthy-regions "do { } while (false) | |||
| 1348 | << Scope->TrueBiasedRegions.size()do { } while (false) | |||
| 1349 | << " falsy-regions " << Scope->FalseBiasedRegions.size()do { } while (false) | |||
| 1350 | << " true-selects " << Scope->TrueBiasedSelects.size()do { } while (false) | |||
| 1351 | << " false-selects " << Scope->FalseBiasedSelects.size() << "\n")do { } while (false); | |||
| 1352 | ORE.emit([&]() { | |||
| 1353 | return OptimizationRemarkMissed( | |||
| 1354 | DEBUG_TYPE"chr", | |||
| 1355 | "DropScopeWithOneBranchOrSelect", | |||
| 1356 | Scope->RegInfos[0].R->getEntry()->getTerminator()) | |||
| 1357 | << "Drop scope with < " | |||
| 1358 | << ore::NV("CHRMergeThreshold", CHRMergeThreshold) | |||
| 1359 | << " biased branch(es) or select(s)"; | |||
| 1360 | }); | |||
| 1361 | continue; | |||
| 1362 | } | |||
| 1363 | Output.push_back(Scope); | |||
| 1364 | } | |||
| 1365 | } | |||
| 1366 | ||||
| 1367 | void CHR::setCHRRegions(SmallVectorImpl<CHRScope *> &Input, | |||
| 1368 | SmallVectorImpl<CHRScope *> &Output) { | |||
| 1369 | for (CHRScope *Scope : Input) { | |||
| 1370 | assert(Scope->HoistStopMap.empty() && Scope->CHRRegions.empty() &&((void)0) | |||
| 1371 | "Empty")((void)0); | |||
| 1372 | setCHRRegions(Scope, Scope); | |||
| 1373 | Output.push_back(Scope); | |||
| 1374 | CHR_DEBUG(do { } while (false) | |||
| 1375 | dbgs() << "setCHRRegions HoistStopMap " << *Scope << "\n";do { } while (false) | |||
| 1376 | for (auto pair : Scope->HoistStopMap) {do { } while (false) | |||
| 1377 | Region *R = pair.first;do { } while (false) | |||
| 1378 | dbgs() << "Region " << R->getNameStr() << "\n";do { } while (false) | |||
| 1379 | for (Instruction *I : pair.second) {do { } while (false) | |||
| 1380 | dbgs() << "HoistStop " << *I << "\n";do { } while (false) | |||
| 1381 | }do { } while (false) | |||
| 1382 | }do { } while (false) | |||
| 1383 | dbgs() << "CHRRegions" << "\n";do { } while (false) | |||
| 1384 | for (RegInfo &RI : Scope->CHRRegions) {do { } while (false) | |||
| 1385 | dbgs() << RI.R->getNameStr() << "\n";do { } while (false) | |||
| 1386 | })do { } while (false); | |||
| 1387 | } | |||
| 1388 | } | |||
| 1389 | ||||
| 1390 | void CHR::setCHRRegions(CHRScope *Scope, CHRScope *OutermostScope) { | |||
| 1391 | DenseSet<Instruction *> Unhoistables; | |||
| 1392 | // Put the biased selects in Unhoistables because they should stay where they | |||
| 1393 | // are and constant-folded after CHR (in case one biased select or a branch | |||
| 1394 | // can depend on another biased select.) | |||
| 1395 | for (RegInfo &RI : Scope->RegInfos) { | |||
| 1396 | for (SelectInst *SI : RI.Selects) { | |||
| 1397 | Unhoistables.insert(SI); | |||
| 1398 | } | |||
| 1399 | } | |||
| 1400 | Instruction *InsertPoint = OutermostScope->BranchInsertPoint; | |||
| 1401 | for (RegInfo &RI : Scope->RegInfos) { | |||
| 1402 | Region *R = RI.R; | |||
| 1403 | DenseSet<Instruction *> HoistStops; | |||
| 1404 | bool IsHoisted = false; | |||
| 1405 | if (RI.HasBranch) { | |||
| 1406 | assert((OutermostScope->TrueBiasedRegions.contains(R) ||((void)0) | |||
| 1407 | OutermostScope->FalseBiasedRegions.contains(R)) &&((void)0) | |||
| 1408 | "Must be truthy or falsy")((void)0); | |||
| 1409 | auto *BI = cast<BranchInst>(R->getEntry()->getTerminator()); | |||
| 1410 | // Note checkHoistValue fills in HoistStops. | |||
| 1411 | DenseMap<Instruction *, bool> Visited; | |||
| 1412 | bool IsHoistable = checkHoistValue(BI->getCondition(), InsertPoint, DT, | |||
| 1413 | Unhoistables, &HoistStops, Visited); | |||
| 1414 | assert(IsHoistable && "Must be hoistable")((void)0); | |||
| 1415 | (void)(IsHoistable); // Unused in release build | |||
| 1416 | IsHoisted = true; | |||
| 1417 | } | |||
| 1418 | for (SelectInst *SI : RI.Selects) { | |||
| 1419 | assert((OutermostScope->TrueBiasedSelects.contains(SI) ||((void)0) | |||
| 1420 | OutermostScope->FalseBiasedSelects.contains(SI)) &&((void)0) | |||
| 1421 | "Must be true or false biased")((void)0); | |||
| 1422 | // Note checkHoistValue fills in HoistStops. | |||
| 1423 | DenseMap<Instruction *, bool> Visited; | |||
| 1424 | bool IsHoistable = checkHoistValue(SI->getCondition(), InsertPoint, DT, | |||
| 1425 | Unhoistables, &HoistStops, Visited); | |||
| 1426 | assert(IsHoistable && "Must be hoistable")((void)0); | |||
| 1427 | (void)(IsHoistable); // Unused in release build | |||
| 1428 | IsHoisted = true; | |||
| 1429 | } | |||
| 1430 | if (IsHoisted) { | |||
| 1431 | OutermostScope->CHRRegions.push_back(RI); | |||
| 1432 | OutermostScope->HoistStopMap[R] = HoistStops; | |||
| 1433 | } | |||
| 1434 | } | |||
| 1435 | for (CHRScope *Sub : Scope->Subs) | |||
| 1436 | setCHRRegions(Sub, OutermostScope); | |||
| 1437 | } | |||
| 1438 | ||||
| 1439 | static bool CHRScopeSorter(CHRScope *Scope1, CHRScope *Scope2) { | |||
| 1440 | return Scope1->RegInfos[0].R->getDepth() < Scope2->RegInfos[0].R->getDepth(); | |||
| 1441 | } | |||
| 1442 | ||||
| 1443 | void CHR::sortScopes(SmallVectorImpl<CHRScope *> &Input, | |||
| 1444 | SmallVectorImpl<CHRScope *> &Output) { | |||
| 1445 | Output.resize(Input.size()); | |||
| 1446 | llvm::copy(Input, Output.begin()); | |||
| 1447 | llvm::stable_sort(Output, CHRScopeSorter); | |||
| 1448 | } | |||
| 1449 | ||||
| 1450 | // Return true if V is already hoisted or was hoisted (along with its operands) | |||
| 1451 | // to the insert point. | |||
| 1452 | static void hoistValue(Value *V, Instruction *HoistPoint, Region *R, | |||
| 1453 | HoistStopMapTy &HoistStopMap, | |||
| 1454 | DenseSet<Instruction *> &HoistedSet, | |||
| 1455 | DenseSet<PHINode *> &TrivialPHIs, | |||
| 1456 | DominatorTree &DT) { | |||
| 1457 | auto IT = HoistStopMap.find(R); | |||
| 1458 | assert(IT != HoistStopMap.end() && "Region must be in hoist stop map")((void)0); | |||
| 1459 | DenseSet<Instruction *> &HoistStops = IT->second; | |||
| 1460 | if (auto *I = dyn_cast<Instruction>(V)) { | |||
| 1461 | if (I == HoistPoint) | |||
| 1462 | return; | |||
| 1463 | if (HoistStops.count(I)) | |||
| 1464 | return; | |||
| 1465 | if (auto *PN = dyn_cast<PHINode>(I)) | |||
| 1466 | if (TrivialPHIs.count(PN)) | |||
| 1467 | // The trivial phi inserted by the previous CHR scope could replace a | |||
| 1468 | // non-phi in HoistStops. Note that since this phi is at the exit of a | |||
| 1469 | // previous CHR scope, which dominates this scope, it's safe to stop | |||
| 1470 | // hoisting there. | |||
| 1471 | return; | |||
| 1472 | if (HoistedSet.count(I)) | |||
| 1473 | // Already hoisted, return. | |||
| 1474 | return; | |||
| 1475 | assert(isHoistableInstructionType(I) && "Unhoistable instruction type")((void)0); | |||
| 1476 | assert(DT.getNode(I->getParent()) && "DT must contain I's block")((void)0); | |||
| 1477 | assert(DT.getNode(HoistPoint->getParent()) &&((void)0) | |||
| 1478 | "DT must contain HoistPoint block")((void)0); | |||
| 1479 | if (DT.dominates(I, HoistPoint)) | |||
| 1480 | // We are already above the hoist point. Stop here. This may be necessary | |||
| 1481 | // when multiple scopes would independently hoist the same | |||
| 1482 | // instruction. Since an outer (dominating) scope would hoist it to its | |||
| 1483 | // entry before an inner (dominated) scope would to its entry, the inner | |||
| 1484 | // scope may see the instruction already hoisted, in which case it | |||
| 1485 | // potentially wrong for the inner scope to hoist it and could cause bad | |||
| 1486 | // IR (non-dominating def), but safe to skip hoisting it instead because | |||
| 1487 | // it's already in a block that dominates the inner scope. | |||
| 1488 | return; | |||
| 1489 | for (Value *Op : I->operands()) { | |||
| 1490 | hoistValue(Op, HoistPoint, R, HoistStopMap, HoistedSet, TrivialPHIs, DT); | |||
| 1491 | } | |||
| 1492 | I->moveBefore(HoistPoint); | |||
| 1493 | HoistedSet.insert(I); | |||
| 1494 | CHR_DEBUG(dbgs() << "hoistValue " << *I << "\n")do { } while (false); | |||
| 1495 | } | |||
| 1496 | } | |||
| 1497 | ||||
| 1498 | // Hoist the dependent condition values of the branches and the selects in the | |||
| 1499 | // scope to the insert point. | |||
| 1500 | static void hoistScopeConditions(CHRScope *Scope, Instruction *HoistPoint, | |||
| 1501 | DenseSet<PHINode *> &TrivialPHIs, | |||
| 1502 | DominatorTree &DT) { | |||
| 1503 | DenseSet<Instruction *> HoistedSet; | |||
| 1504 | for (const RegInfo &RI : Scope->CHRRegions) { | |||
| 1505 | Region *R = RI.R; | |||
| 1506 | bool IsTrueBiased = Scope->TrueBiasedRegions.count(R); | |||
| 1507 | bool IsFalseBiased = Scope->FalseBiasedRegions.count(R); | |||
| 1508 | if (RI.HasBranch && (IsTrueBiased || IsFalseBiased)) { | |||
| 1509 | auto *BI = cast<BranchInst>(R->getEntry()->getTerminator()); | |||
| 1510 | hoistValue(BI->getCondition(), HoistPoint, R, Scope->HoistStopMap, | |||
| 1511 | HoistedSet, TrivialPHIs, DT); | |||
| 1512 | } | |||
| 1513 | for (SelectInst *SI : RI.Selects) { | |||
| 1514 | bool IsTrueBiased = Scope->TrueBiasedSelects.count(SI); | |||
| 1515 | bool IsFalseBiased = Scope->FalseBiasedSelects.count(SI); | |||
| 1516 | if (!(IsTrueBiased || IsFalseBiased)) | |||
| 1517 | continue; | |||
| 1518 | hoistValue(SI->getCondition(), HoistPoint, R, Scope->HoistStopMap, | |||
| 1519 | HoistedSet, TrivialPHIs, DT); | |||
| 1520 | } | |||
| 1521 | } | |||
| 1522 | } | |||
| 1523 | ||||
| 1524 | // Negate the predicate if an ICmp if it's used only by branches or selects by | |||
| 1525 | // swapping the operands of the branches or the selects. Returns true if success. | |||
| 1526 | static bool negateICmpIfUsedByBranchOrSelectOnly(ICmpInst *ICmp, | |||
| 1527 | Instruction *ExcludedUser, | |||
| 1528 | CHRScope *Scope) { | |||
| 1529 | for (User *U : ICmp->users()) { | |||
| 1530 | if (U == ExcludedUser) | |||
| 1531 | continue; | |||
| 1532 | if (isa<BranchInst>(U) && cast<BranchInst>(U)->isConditional()) | |||
| 1533 | continue; | |||
| 1534 | if (isa<SelectInst>(U) && cast<SelectInst>(U)->getCondition() == ICmp) | |||
| 1535 | continue; | |||
| 1536 | return false; | |||
| 1537 | } | |||
| 1538 | for (User *U : ICmp->users()) { | |||
| 1539 | if (U == ExcludedUser) | |||
| 1540 | continue; | |||
| 1541 | if (auto *BI = dyn_cast<BranchInst>(U)) { | |||
| 1542 | assert(BI->isConditional() && "Must be conditional")((void)0); | |||
| 1543 | BI->swapSuccessors(); | |||
| 1544 | // Don't need to swap this in terms of | |||
| 1545 | // TrueBiasedRegions/FalseBiasedRegions because true-based/false-based | |||
| 1546 | // mean whehter the branch is likely go into the if-then rather than | |||
| 1547 | // successor0/successor1 and because we can tell which edge is the then or | |||
| 1548 | // the else one by comparing the destination to the region exit block. | |||
| 1549 | continue; | |||
| 1550 | } | |||
| 1551 | if (auto *SI = dyn_cast<SelectInst>(U)) { | |||
| 1552 | // Swap operands | |||
| 1553 | SI->swapValues(); | |||
| 1554 | SI->swapProfMetadata(); | |||
| 1555 | if (Scope->TrueBiasedSelects.count(SI)) { | |||
| 1556 | assert(Scope->FalseBiasedSelects.count(SI) == 0 &&((void)0) | |||
| 1557 | "Must not be already in")((void)0); | |||
| 1558 | Scope->FalseBiasedSelects.insert(SI); | |||
| 1559 | } else if (Scope->FalseBiasedSelects.count(SI)) { | |||
| 1560 | assert(Scope->TrueBiasedSelects.count(SI) == 0 &&((void)0) | |||
| 1561 | "Must not be already in")((void)0); | |||
| 1562 | Scope->TrueBiasedSelects.insert(SI); | |||
| 1563 | } | |||
| 1564 | continue; | |||
| 1565 | } | |||
| 1566 | llvm_unreachable("Must be a branch or a select")__builtin_unreachable(); | |||
| 1567 | } | |||
| 1568 | ICmp->setPredicate(CmpInst::getInversePredicate(ICmp->getPredicate())); | |||
| 1569 | return true; | |||
| 1570 | } | |||
| 1571 | ||||
| 1572 | // A helper for transformScopes. Insert a trivial phi at the scope exit block | |||
| 1573 | // for a value that's defined in the scope but used outside it (meaning it's | |||
| 1574 | // alive at the exit block). | |||
| 1575 | static void insertTrivialPHIs(CHRScope *Scope, | |||
| 1576 | BasicBlock *EntryBlock, BasicBlock *ExitBlock, | |||
| 1577 | DenseSet<PHINode *> &TrivialPHIs) { | |||
| 1578 | SmallSetVector<BasicBlock *, 8> BlocksInScope; | |||
| 1579 | for (RegInfo &RI : Scope->RegInfos) { | |||
| 1580 | for (BasicBlock *BB : RI.R->blocks()) { // This includes the blocks in the | |||
| 1581 | // sub-Scopes. | |||
| 1582 | BlocksInScope.insert(BB); | |||
| 1583 | } | |||
| 1584 | } | |||
| 1585 | CHR_DEBUG({do { } while (false) | |||
| 1586 | dbgs() << "Inserting redundant phis\n";do { } while (false) | |||
| 1587 | for (BasicBlock *BB : BlocksInScope)do { } while (false) | |||
| 1588 | dbgs() << "BlockInScope " << BB->getName() << "\n";do { } while (false) | |||
| 1589 | })do { } while (false); | |||
| 1590 | for (BasicBlock *BB : BlocksInScope) { | |||
| 1591 | for (Instruction &I : *BB) { | |||
| 1592 | SmallVector<Instruction *, 8> Users; | |||
| 1593 | for (User *U : I.users()) { | |||
| 1594 | if (auto *UI = dyn_cast<Instruction>(U)) { | |||
| 1595 | if (BlocksInScope.count(UI->getParent()) == 0 && | |||
| 1596 | // Unless there's already a phi for I at the exit block. | |||
| 1597 | !(isa<PHINode>(UI) && UI->getParent() == ExitBlock)) { | |||
| 1598 | CHR_DEBUG(dbgs() << "V " << I << "\n")do { } while (false); | |||
| 1599 | CHR_DEBUG(dbgs() << "Used outside scope by user " << *UI << "\n")do { } while (false); | |||
| 1600 | Users.push_back(UI); | |||
| 1601 | } else if (UI->getParent() == EntryBlock && isa<PHINode>(UI)) { | |||
| 1602 | // There's a loop backedge from a block that's dominated by this | |||
| 1603 | // scope to the entry block. | |||
| 1604 | CHR_DEBUG(dbgs() << "V " << I << "\n")do { } while (false); | |||
| 1605 | CHR_DEBUG(dbgs()do { } while (false) | |||
| 1606 | << "Used at entry block (for a back edge) by a phi user "do { } while (false) | |||
| 1607 | << *UI << "\n")do { } while (false); | |||
| 1608 | Users.push_back(UI); | |||
| 1609 | } | |||
| 1610 | } | |||
| 1611 | } | |||
| 1612 | if (Users.size() > 0) { | |||
| 1613 | // Insert a trivial phi for I (phi [&I, P0], [&I, P1], ...) at | |||
| 1614 | // ExitBlock. Replace I with the new phi in UI unless UI is another | |||
| 1615 | // phi at ExitBlock. | |||
| 1616 | PHINode *PN = PHINode::Create(I.getType(), pred_size(ExitBlock), "", | |||
| 1617 | &ExitBlock->front()); | |||
| 1618 | for (BasicBlock *Pred : predecessors(ExitBlock)) { | |||
| 1619 | PN->addIncoming(&I, Pred); | |||
| 1620 | } | |||
| 1621 | TrivialPHIs.insert(PN); | |||
| 1622 | CHR_DEBUG(dbgs() << "Insert phi " << *PN << "\n")do { } while (false); | |||
| 1623 | for (Instruction *UI : Users) { | |||
| 1624 | for (unsigned J = 0, NumOps = UI->getNumOperands(); J < NumOps; ++J) { | |||
| 1625 | if (UI->getOperand(J) == &I) { | |||
| 1626 | UI->setOperand(J, PN); | |||
| 1627 | } | |||
| 1628 | } | |||
| 1629 | CHR_DEBUG(dbgs() << "Updated user " << *UI << "\n")do { } while (false); | |||
| 1630 | } | |||
| 1631 | } | |||
| 1632 | } | |||
| 1633 | } | |||
| 1634 | } | |||
| 1635 | ||||
| 1636 | // Assert that all the CHR regions of the scope have a biased branch or select. | |||
| 1637 | static void LLVM_ATTRIBUTE_UNUSED__attribute__((__unused__)) | |||
| 1638 | assertCHRRegionsHaveBiasedBranchOrSelect(CHRScope *Scope) { | |||
| 1639 | #ifndef NDEBUG1 | |||
| 1640 | auto HasBiasedBranchOrSelect = [](RegInfo &RI, CHRScope *Scope) { | |||
| 1641 | if (Scope->TrueBiasedRegions.count(RI.R) || | |||
| 1642 | Scope->FalseBiasedRegions.count(RI.R)) | |||
| 1643 | return true; | |||
| 1644 | for (SelectInst *SI : RI.Selects) | |||
| 1645 | if (Scope->TrueBiasedSelects.count(SI) || | |||
| 1646 | Scope->FalseBiasedSelects.count(SI)) | |||
| 1647 | return true; | |||
| 1648 | return false; | |||
| 1649 | }; | |||
| 1650 | for (RegInfo &RI : Scope->CHRRegions) { | |||
| 1651 | assert(HasBiasedBranchOrSelect(RI, Scope) &&((void)0) | |||
| 1652 | "Must have biased branch or select")((void)0); | |||
| 1653 | } | |||
| 1654 | #endif | |||
| 1655 | } | |||
| 1656 | ||||
| 1657 | // Assert that all the condition values of the biased branches and selects have | |||
| 1658 | // been hoisted to the pre-entry block or outside of the scope. | |||
| 1659 | static void LLVM_ATTRIBUTE_UNUSED__attribute__((__unused__)) assertBranchOrSelectConditionHoisted( | |||
| 1660 | CHRScope *Scope, BasicBlock *PreEntryBlock) { | |||
| 1661 | CHR_DEBUG(dbgs() << "Biased regions condition values \n")do { } while (false); | |||
| 1662 | for (RegInfo &RI : Scope->CHRRegions) { | |||
| 1663 | Region *R = RI.R; | |||
| 1664 | bool IsTrueBiased = Scope->TrueBiasedRegions.count(R); | |||
| 1665 | bool IsFalseBiased = Scope->FalseBiasedRegions.count(R); | |||
| 1666 | if (RI.HasBranch && (IsTrueBiased || IsFalseBiased)) { | |||
| 1667 | auto *BI = cast<BranchInst>(R->getEntry()->getTerminator()); | |||
| 1668 | Value *V = BI->getCondition(); | |||
| 1669 | CHR_DEBUG(dbgs() << *V << "\n")do { } while (false); | |||
| 1670 | if (auto *I = dyn_cast<Instruction>(V)) { | |||
| 1671 | (void)(I); // Unused in release build. | |||
| 1672 | assert((I->getParent() == PreEntryBlock ||((void)0) | |||
| 1673 | !Scope->contains(I)) &&((void)0) | |||
| 1674 | "Must have been hoisted to PreEntryBlock or outside the scope")((void)0); | |||
| 1675 | } | |||
| 1676 | } | |||
| 1677 | for (SelectInst *SI : RI.Selects) { | |||
| 1678 | bool IsTrueBiased = Scope->TrueBiasedSelects.count(SI); | |||
| 1679 | bool IsFalseBiased = Scope->FalseBiasedSelects.count(SI); | |||
| 1680 | if (!(IsTrueBiased || IsFalseBiased)) | |||
| 1681 | continue; | |||
| 1682 | Value *V = SI->getCondition(); | |||
| 1683 | CHR_DEBUG(dbgs() << *V << "\n")do { } while (false); | |||
| 1684 | if (auto *I = dyn_cast<Instruction>(V)) { | |||
| 1685 | (void)(I); // Unused in release build. | |||
| 1686 | assert((I->getParent() == PreEntryBlock ||((void)0) | |||
| 1687 | !Scope->contains(I)) &&((void)0) | |||
| 1688 | "Must have been hoisted to PreEntryBlock or outside the scope")((void)0); | |||
| 1689 | } | |||
| 1690 | } | |||
| 1691 | } | |||
| 1692 | } | |||
| 1693 | ||||
| 1694 | void CHR::transformScopes(CHRScope *Scope, DenseSet<PHINode *> &TrivialPHIs) { | |||
| 1695 | CHR_DEBUG(dbgs() << "transformScopes " << *Scope << "\n")do { } while (false); | |||
| 1696 | ||||
| 1697 | assert(Scope->RegInfos.size() >= 1 && "Should have at least one Region")((void)0); | |||
| 1698 | Region *FirstRegion = Scope->RegInfos[0].R; | |||
| 1699 | BasicBlock *EntryBlock = FirstRegion->getEntry(); | |||
| 1700 | Region *LastRegion = Scope->RegInfos[Scope->RegInfos.size() - 1].R; | |||
| 1701 | BasicBlock *ExitBlock = LastRegion->getExit(); | |||
| 1702 | Optional<uint64_t> ProfileCount = BFI.getBlockProfileCount(EntryBlock); | |||
| 1703 | ||||
| 1704 | if (ExitBlock) { | |||
| 1705 | // Insert a trivial phi at the exit block (where the CHR hot path and the | |||
| 1706 | // cold path merges) for a value that's defined in the scope but used | |||
| 1707 | // outside it (meaning it's alive at the exit block). We will add the | |||
| 1708 | // incoming values for the CHR cold paths to it below. Without this, we'd | |||
| 1709 | // miss updating phi's for such values unless there happens to already be a | |||
| 1710 | // phi for that value there. | |||
| 1711 | insertTrivialPHIs(Scope, EntryBlock, ExitBlock, TrivialPHIs); | |||
| 1712 | } | |||
| 1713 | ||||
| 1714 | // Split the entry block of the first region. The new block becomes the new | |||
| 1715 | // entry block of the first region. The old entry block becomes the block to | |||
| 1716 | // insert the CHR branch into. Note DT gets updated. Since DT gets updated | |||
| 1717 | // through the split, we update the entry of the first region after the split, | |||
| 1718 | // and Region only points to the entry and the exit blocks, rather than | |||
| 1719 | // keeping everything in a list or set, the blocks membership and the | |||
| 1720 | // entry/exit blocks of the region are still valid after the split. | |||
| 1721 | CHR_DEBUG(dbgs() << "Splitting entry block " << EntryBlock->getName()do { } while (false) | |||
| 1722 | << " at " << *Scope->BranchInsertPoint << "\n")do { } while (false); | |||
| 1723 | BasicBlock *NewEntryBlock = | |||
| 1724 | SplitBlock(EntryBlock, Scope->BranchInsertPoint, &DT); | |||
| 1725 | assert(NewEntryBlock->getSinglePredecessor() == EntryBlock &&((void)0) | |||
| 1726 | "NewEntryBlock's only pred must be EntryBlock")((void)0); | |||
| 1727 | FirstRegion->replaceEntryRecursive(NewEntryBlock); | |||
| 1728 | BasicBlock *PreEntryBlock = EntryBlock; | |||
| 1729 | ||||
| 1730 | ValueToValueMapTy VMap; | |||
| 1731 | // Clone the blocks in the scope (excluding the PreEntryBlock) to split into a | |||
| 1732 | // hot path (originals) and a cold path (clones) and update the PHIs at the | |||
| 1733 | // exit block. | |||
| 1734 | cloneScopeBlocks(Scope, PreEntryBlock, ExitBlock, LastRegion, VMap); | |||
| 1735 | ||||
| 1736 | // Replace the old (placeholder) branch with the new (merged) conditional | |||
| 1737 | // branch. | |||
| 1738 | BranchInst *MergedBr = createMergedBranch(PreEntryBlock, EntryBlock, | |||
| 1739 | NewEntryBlock, VMap); | |||
| 1740 | ||||
| 1741 | #ifndef NDEBUG1 | |||
| 1742 | assertCHRRegionsHaveBiasedBranchOrSelect(Scope); | |||
| 1743 | #endif | |||
| 1744 | ||||
| 1745 | // Hoist the conditional values of the branches/selects. | |||
| 1746 | hoistScopeConditions(Scope, PreEntryBlock->getTerminator(), TrivialPHIs, DT); | |||
| 1747 | ||||
| 1748 | #ifndef NDEBUG1 | |||
| 1749 | assertBranchOrSelectConditionHoisted(Scope, PreEntryBlock); | |||
| 1750 | #endif | |||
| 1751 | ||||
| 1752 | // Create the combined branch condition and constant-fold the branches/selects | |||
| 1753 | // in the hot path. | |||
| 1754 | fixupBranchesAndSelects(Scope, PreEntryBlock, MergedBr, | |||
| 1755 | ProfileCount ? ProfileCount.getValue() : 0); | |||
| 1756 | } | |||
| 1757 | ||||
| 1758 | // A helper for transformScopes. Clone the blocks in the scope (excluding the | |||
| 1759 | // PreEntryBlock) to split into a hot path and a cold path and update the PHIs | |||
| 1760 | // at the exit block. | |||
| 1761 | void CHR::cloneScopeBlocks(CHRScope *Scope, | |||
| 1762 | BasicBlock *PreEntryBlock, | |||
| 1763 | BasicBlock *ExitBlock, | |||
| 1764 | Region *LastRegion, | |||
| 1765 | ValueToValueMapTy &VMap) { | |||
| 1766 | // Clone all the blocks. The original blocks will be the hot-path | |||
| 1767 | // CHR-optimized code and the cloned blocks will be the original unoptimized | |||
| 1768 | // code. This is so that the block pointers from the | |||
| 1769 | // CHRScope/Region/RegionInfo can stay valid in pointing to the hot-path code | |||
| 1770 | // which CHR should apply to. | |||
| 1771 | SmallVector<BasicBlock*, 8> NewBlocks; | |||
| 1772 | for (RegInfo &RI : Scope->RegInfos) | |||
| 1773 | for (BasicBlock *BB : RI.R->blocks()) { // This includes the blocks in the | |||
| 1774 | // sub-Scopes. | |||
| 1775 | assert(BB != PreEntryBlock && "Don't copy the preetntry block")((void)0); | |||
| 1776 | BasicBlock *NewBB = CloneBasicBlock(BB, VMap, ".nonchr", &F); | |||
| 1777 | NewBlocks.push_back(NewBB); | |||
| 1778 | VMap[BB] = NewBB; | |||
| 1779 | } | |||
| 1780 | ||||
| 1781 | // Place the cloned blocks right after the original blocks (right before the | |||
| 1782 | // exit block of.) | |||
| 1783 | if (ExitBlock) | |||
| 1784 | F.getBasicBlockList().splice(ExitBlock->getIterator(), | |||
| 1785 | F.getBasicBlockList(), | |||
| 1786 | NewBlocks[0]->getIterator(), F.end()); | |||
| 1787 | ||||
| 1788 | // Update the cloned blocks/instructions to refer to themselves. | |||
| 1789 | for (unsigned i = 0, e = NewBlocks.size(); i != e; ++i) | |||
| 1790 | for (Instruction &I : *NewBlocks[i]) | |||
| 1791 | RemapInstruction(&I, VMap, | |||
| 1792 | RF_NoModuleLevelChanges | RF_IgnoreMissingLocals); | |||
| 1793 | ||||
| 1794 | // Add the cloned blocks to the PHIs of the exit blocks. ExitBlock is null for | |||
| 1795 | // the top-level region but we don't need to add PHIs. The trivial PHIs | |||
| 1796 | // inserted above will be updated here. | |||
| 1797 | if (ExitBlock) | |||
| 1798 | for (PHINode &PN : ExitBlock->phis()) | |||
| 1799 | for (unsigned I = 0, NumOps = PN.getNumIncomingValues(); I < NumOps; | |||
| 1800 | ++I) { | |||
| 1801 | BasicBlock *Pred = PN.getIncomingBlock(I); | |||
| 1802 | if (LastRegion->contains(Pred)) { | |||
| 1803 | Value *V = PN.getIncomingValue(I); | |||
| 1804 | auto It = VMap.find(V); | |||
| 1805 | if (It != VMap.end()) V = It->second; | |||
| 1806 | assert(VMap.find(Pred) != VMap.end() && "Pred must have been cloned")((void)0); | |||
| 1807 | PN.addIncoming(V, cast<BasicBlock>(VMap[Pred])); | |||
| 1808 | } | |||
| 1809 | } | |||
| 1810 | } | |||
| 1811 | ||||
| 1812 | // A helper for transformScope. Replace the old (placeholder) branch with the | |||
| 1813 | // new (merged) conditional branch. | |||
| 1814 | BranchInst *CHR::createMergedBranch(BasicBlock *PreEntryBlock, | |||
| 1815 | BasicBlock *EntryBlock, | |||
| 1816 | BasicBlock *NewEntryBlock, | |||
| 1817 | ValueToValueMapTy &VMap) { | |||
| 1818 | BranchInst *OldBR = cast<BranchInst>(PreEntryBlock->getTerminator()); | |||
| 1819 | assert(OldBR->isUnconditional() && OldBR->getSuccessor(0) == NewEntryBlock &&((void)0) | |||
| 1820 | "SplitBlock did not work correctly!")((void)0); | |||
| 1821 | assert(NewEntryBlock->getSinglePredecessor() == EntryBlock &&((void)0) | |||
| 1822 | "NewEntryBlock's only pred must be EntryBlock")((void)0); | |||
| 1823 | assert(VMap.find(NewEntryBlock) != VMap.end() &&((void)0) | |||
| 1824 | "NewEntryBlock must have been copied")((void)0); | |||
| 1825 | OldBR->dropAllReferences(); | |||
| 1826 | OldBR->eraseFromParent(); | |||
| 1827 | // The true predicate is a placeholder. It will be replaced later in | |||
| 1828 | // fixupBranchesAndSelects(). | |||
| 1829 | BranchInst *NewBR = BranchInst::Create(NewEntryBlock, | |||
| 1830 | cast<BasicBlock>(VMap[NewEntryBlock]), | |||
| 1831 | ConstantInt::getTrue(F.getContext())); | |||
| 1832 | PreEntryBlock->getInstList().push_back(NewBR); | |||
| 1833 | assert(NewEntryBlock->getSinglePredecessor() == EntryBlock &&((void)0) | |||
| 1834 | "NewEntryBlock's only pred must be EntryBlock")((void)0); | |||
| 1835 | return NewBR; | |||
| 1836 | } | |||
| 1837 | ||||
| 1838 | // A helper for transformScopes. Create the combined branch condition and | |||
| 1839 | // constant-fold the branches/selects in the hot path. | |||
| 1840 | void CHR::fixupBranchesAndSelects(CHRScope *Scope, | |||
| 1841 | BasicBlock *PreEntryBlock, | |||
| 1842 | BranchInst *MergedBR, | |||
| 1843 | uint64_t ProfileCount) { | |||
| 1844 | Value *MergedCondition = ConstantInt::getTrue(F.getContext()); | |||
| 1845 | BranchProbability CHRBranchBias(1, 1); | |||
| 1846 | uint64_t NumCHRedBranches = 0; | |||
| 1847 | IRBuilder<> IRB(PreEntryBlock->getTerminator()); | |||
| 1848 | for (RegInfo &RI : Scope->CHRRegions) { | |||
| 1849 | Region *R = RI.R; | |||
| 1850 | if (RI.HasBranch) { | |||
| 1851 | fixupBranch(R, Scope, IRB, MergedCondition, CHRBranchBias); | |||
| 1852 | ++NumCHRedBranches; | |||
| 1853 | } | |||
| 1854 | for (SelectInst *SI : RI.Selects) { | |||
| 1855 | fixupSelect(SI, Scope, IRB, MergedCondition, CHRBranchBias); | |||
| 1856 | ++NumCHRedBranches; | |||
| 1857 | } | |||
| 1858 | } | |||
| 1859 | Stats.NumBranchesDelta += NumCHRedBranches - 1; | |||
| 1860 | Stats.WeightedNumBranchesDelta += (NumCHRedBranches - 1) * ProfileCount; | |||
| 1861 | ORE.emit([&]() { | |||
| 1862 | return OptimizationRemark(DEBUG_TYPE"chr", | |||
| 1863 | "CHR", | |||
| 1864 | // Refer to the hot (original) path | |||
| 1865 | MergedBR->getSuccessor(0)->getTerminator()) | |||
| 1866 | << "Merged " << ore::NV("NumCHRedBranches", NumCHRedBranches) | |||
| 1867 | << " branches or selects"; | |||
| 1868 | }); | |||
| 1869 | MergedBR->setCondition(MergedCondition); | |||
| 1870 | uint32_t Weights[] = { | |||
| 1871 | static_cast<uint32_t>(CHRBranchBias.scale(1000)), | |||
| 1872 | static_cast<uint32_t>(CHRBranchBias.getCompl().scale(1000)), | |||
| 1873 | }; | |||
| 1874 | MDBuilder MDB(F.getContext()); | |||
| 1875 | MergedBR->setMetadata(LLVMContext::MD_prof, MDB.createBranchWeights(Weights)); | |||
| 1876 | CHR_DEBUG(dbgs() << "CHR branch bias " << Weights[0] << ":" << Weights[1]do { } while (false) | |||
| 1877 | << "\n")do { } while (false); | |||
| 1878 | } | |||
| 1879 | ||||
| 1880 | // A helper for fixupBranchesAndSelects. Add to the combined branch condition | |||
| 1881 | // and constant-fold a branch in the hot path. | |||
| 1882 | void CHR::fixupBranch(Region *R, CHRScope *Scope, | |||
| 1883 | IRBuilder<> &IRB, | |||
| 1884 | Value *&MergedCondition, | |||
| 1885 | BranchProbability &CHRBranchBias) { | |||
| 1886 | bool IsTrueBiased = Scope->TrueBiasedRegions.count(R); | |||
| 1887 | assert((IsTrueBiased || Scope->FalseBiasedRegions.count(R)) &&((void)0) | |||
| 1888 | "Must be truthy or falsy")((void)0); | |||
| 1889 | auto *BI = cast<BranchInst>(R->getEntry()->getTerminator()); | |||
| 1890 | assert(BranchBiasMap.find(R) != BranchBiasMap.end() &&((void)0) | |||
| 1891 | "Must be in the bias map")((void)0); | |||
| 1892 | BranchProbability Bias = BranchBiasMap[R]; | |||
| 1893 | assert(Bias >= getCHRBiasThreshold() && "Must be highly biased")((void)0); | |||
| 1894 | // Take the min. | |||
| 1895 | if (CHRBranchBias > Bias) | |||
| 1896 | CHRBranchBias = Bias; | |||
| 1897 | BasicBlock *IfThen = BI->getSuccessor(1); | |||
| 1898 | BasicBlock *IfElse = BI->getSuccessor(0); | |||
| 1899 | BasicBlock *RegionExitBlock = R->getExit(); | |||
| 1900 | assert(RegionExitBlock && "Null ExitBlock")((void)0); | |||
| 1901 | assert((IfThen == RegionExitBlock || IfElse == RegionExitBlock) &&((void)0) | |||
| 1902 | IfThen != IfElse && "Invariant from findScopes")((void)0); | |||
| 1903 | if (IfThen == RegionExitBlock) { | |||
| 1904 | // Swap them so that IfThen means going into it and IfElse means skipping | |||
| 1905 | // it. | |||
| 1906 | std::swap(IfThen, IfElse); | |||
| 1907 | } | |||
| 1908 | CHR_DEBUG(dbgs() << "IfThen " << IfThen->getName()do { } while (false) | |||
| 1909 | << " IfElse " << IfElse->getName() << "\n")do { } while (false); | |||
| 1910 | Value *Cond = BI->getCondition(); | |||
| 1911 | BasicBlock *HotTarget = IsTrueBiased ? IfThen : IfElse; | |||
| 1912 | bool ConditionTrue = HotTarget == BI->getSuccessor(0); | |||
| 1913 | addToMergedCondition(ConditionTrue, Cond, BI, Scope, IRB, | |||
| 1914 | MergedCondition); | |||
| 1915 | // Constant-fold the branch at ClonedEntryBlock. | |||
| 1916 | assert(ConditionTrue == (HotTarget == BI->getSuccessor(0)) &&((void)0) | |||
| 1917 | "The successor shouldn't change")((void)0); | |||
| 1918 | Value *NewCondition = ConditionTrue ? | |||
| 1919 | ConstantInt::getTrue(F.getContext()) : | |||
| 1920 | ConstantInt::getFalse(F.getContext()); | |||
| 1921 | BI->setCondition(NewCondition); | |||
| 1922 | } | |||
| 1923 | ||||
| 1924 | // A helper for fixupBranchesAndSelects. Add to the combined branch condition | |||
| 1925 | // and constant-fold a select in the hot path. | |||
| 1926 | void CHR::fixupSelect(SelectInst *SI, CHRScope *Scope, | |||
| 1927 | IRBuilder<> &IRB, | |||
| 1928 | Value *&MergedCondition, | |||
| 1929 | BranchProbability &CHRBranchBias) { | |||
| 1930 | bool IsTrueBiased = Scope->TrueBiasedSelects.count(SI); | |||
| 1931 | assert((IsTrueBiased ||((void)0) | |||
| 1932 | Scope->FalseBiasedSelects.count(SI)) && "Must be biased")((void)0); | |||
| 1933 | assert(SelectBiasMap.find(SI) != SelectBiasMap.end() &&((void)0) | |||
| 1934 | "Must be in the bias map")((void)0); | |||
| 1935 | BranchProbability Bias = SelectBiasMap[SI]; | |||
| 1936 | assert(Bias >= getCHRBiasThreshold() && "Must be highly biased")((void)0); | |||
| 1937 | // Take the min. | |||
| 1938 | if (CHRBranchBias > Bias) | |||
| 1939 | CHRBranchBias = Bias; | |||
| 1940 | Value *Cond = SI->getCondition(); | |||
| 1941 | addToMergedCondition(IsTrueBiased, Cond, SI, Scope, IRB, | |||
| 1942 | MergedCondition); | |||
| 1943 | Value *NewCondition = IsTrueBiased ? | |||
| 1944 | ConstantInt::getTrue(F.getContext()) : | |||
| 1945 | ConstantInt::getFalse(F.getContext()); | |||
| 1946 | SI->setCondition(NewCondition); | |||
| 1947 | } | |||
| 1948 | ||||
| 1949 | // A helper for fixupBranch/fixupSelect. Add a branch condition to the merged | |||
| 1950 | // condition. | |||
| 1951 | void CHR::addToMergedCondition(bool IsTrueBiased, Value *Cond, | |||
| 1952 | Instruction *BranchOrSelect, | |||
| 1953 | CHRScope *Scope, | |||
| 1954 | IRBuilder<> &IRB, | |||
| 1955 | Value *&MergedCondition) { | |||
| 1956 | if (IsTrueBiased) { | |||
| 1957 | MergedCondition = IRB.CreateAnd(MergedCondition, Cond); | |||
| 1958 | } else { | |||
| 1959 | // If Cond is an icmp and all users of V except for BranchOrSelect is a | |||
| 1960 | // branch, negate the icmp predicate and swap the branch targets and avoid | |||
| 1961 | // inserting an Xor to negate Cond. | |||
| 1962 | bool Done = false; | |||
| 1963 | if (auto *ICmp = dyn_cast<ICmpInst>(Cond)) | |||
| 1964 | if (negateICmpIfUsedByBranchOrSelectOnly(ICmp, BranchOrSelect, Scope)) { | |||
| 1965 | MergedCondition = IRB.CreateAnd(MergedCondition, Cond); | |||
| 1966 | Done = true; | |||
| 1967 | } | |||
| 1968 | if (!Done) { | |||
| 1969 | Value *Negate = IRB.CreateXor( | |||
| 1970 | ConstantInt::getTrue(F.getContext()), Cond); | |||
| 1971 | MergedCondition = IRB.CreateAnd(MergedCondition, Negate); | |||
| 1972 | } | |||
| 1973 | } | |||
| 1974 | } | |||
| 1975 | ||||
| 1976 | void CHR::transformScopes(SmallVectorImpl<CHRScope *> &CHRScopes) { | |||
| 1977 | unsigned I = 0; | |||
| 1978 | DenseSet<PHINode *> TrivialPHIs; | |||
| 1979 | for (CHRScope *Scope : CHRScopes) { | |||
| 1980 | transformScopes(Scope, TrivialPHIs); | |||
| 1981 | CHR_DEBUG(do { } while (false) | |||
| 1982 | std::ostringstream oss;do { } while (false) | |||
| 1983 | oss << " after transformScopes " << I++;do { } while (false) | |||
| 1984 | dumpIR(F, oss.str().c_str(), nullptr))do { } while (false); | |||
| 1985 | (void)I; | |||
| 1986 | } | |||
| 1987 | } | |||
| 1988 | ||||
| 1989 | static void LLVM_ATTRIBUTE_UNUSED__attribute__((__unused__)) | |||
| 1990 | dumpScopes(SmallVectorImpl<CHRScope *> &Scopes, const char *Label) { | |||
| 1991 | dbgs() << Label << " " << Scopes.size() << "\n"; | |||
| 1992 | for (CHRScope *Scope : Scopes) { | |||
| 1993 | dbgs() << *Scope << "\n"; | |||
| 1994 | } | |||
| 1995 | } | |||
| 1996 | ||||
| 1997 | bool CHR::run() { | |||
| 1998 | if (!shouldApply(F, PSI)) | |||
| 1999 | return false; | |||
| 2000 | ||||
| 2001 | CHR_DEBUG(dumpIR(F, "before", nullptr))do { } while (false); | |||
| 2002 | ||||
| 2003 | bool Changed = false; | |||
| 2004 | { | |||
| 2005 | CHR_DEBUG(do { } while (false) | |||
| 2006 | dbgs() << "RegionInfo:\n";do { } while (false) | |||
| 2007 | RI.print(dbgs()))do { } while (false); | |||
| 2008 | ||||
| 2009 | // Recursively traverse the region tree and find regions that have biased | |||
| 2010 | // branches and/or selects and create scopes. | |||
| 2011 | SmallVector<CHRScope *, 8> AllScopes; | |||
| 2012 | findScopes(AllScopes); | |||
| 2013 | CHR_DEBUG(dumpScopes(AllScopes, "All scopes"))do { } while (false); | |||
| 2014 | ||||
| 2015 | // Split the scopes if 1) the conditiona values of the biased | |||
| 2016 | // branches/selects of the inner/lower scope can't be hoisted up to the | |||
| 2017 | // outermost/uppermost scope entry, or 2) the condition values of the biased | |||
| 2018 | // branches/selects in a scope (including subscopes) don't share at least | |||
| 2019 | // one common value. | |||
| 2020 | SmallVector<CHRScope *, 8> SplitScopes; | |||
| 2021 | splitScopes(AllScopes, SplitScopes); | |||
| 2022 | CHR_DEBUG(dumpScopes(SplitScopes, "Split scopes"))do { } while (false); | |||
| 2023 | ||||
| 2024 | // After splitting, set the biased regions and selects of a scope (a tree | |||
| 2025 | // root) that include those of the subscopes. | |||
| 2026 | classifyBiasedScopes(SplitScopes); | |||
| 2027 | CHR_DEBUG(dbgs() << "Set per-scope bias " << SplitScopes.size() << "\n")do { } while (false); | |||
| 2028 | ||||
| 2029 | // Filter out the scopes that has only one biased region or select (CHR | |||
| 2030 | // isn't useful in such a case). | |||
| 2031 | SmallVector<CHRScope *, 8> FilteredScopes; | |||
| 2032 | filterScopes(SplitScopes, FilteredScopes); | |||
| 2033 | CHR_DEBUG(dumpScopes(FilteredScopes, "Filtered scopes"))do { } while (false); | |||
| 2034 | ||||
| 2035 | // Set the regions to be CHR'ed and their hoist stops for each scope. | |||
| 2036 | SmallVector<CHRScope *, 8> SetScopes; | |||
| 2037 | setCHRRegions(FilteredScopes, SetScopes); | |||
| 2038 | CHR_DEBUG(dumpScopes(SetScopes, "Set CHR regions"))do { } while (false); | |||
| 2039 | ||||
| 2040 | // Sort CHRScopes by the depth so that outer CHRScopes comes before inner | |||
| 2041 | // ones. We need to apply CHR from outer to inner so that we apply CHR only | |||
| 2042 | // to the hot path, rather than both hot and cold paths. | |||
| 2043 | SmallVector<CHRScope *, 8> SortedScopes; | |||
| 2044 | sortScopes(SetScopes, SortedScopes); | |||
| 2045 | CHR_DEBUG(dumpScopes(SortedScopes, "Sorted scopes"))do { } while (false); | |||
| 2046 | ||||
| 2047 | CHR_DEBUG(do { } while (false) | |||
| 2048 | dbgs() << "RegionInfo:\n";do { } while (false) | |||
| 2049 | RI.print(dbgs()))do { } while (false); | |||
| 2050 | ||||
| 2051 | // Apply the CHR transformation. | |||
| 2052 | if (!SortedScopes.empty()) { | |||
| 2053 | transformScopes(SortedScopes); | |||
| 2054 | Changed = true; | |||
| 2055 | } | |||
| 2056 | } | |||
| 2057 | ||||
| 2058 | if (Changed) { | |||
| 2059 | CHR_DEBUG(dumpIR(F, "after", &Stats))do { } while (false); | |||
| 2060 | ORE.emit([&]() { | |||
| 2061 | return OptimizationRemark(DEBUG_TYPE"chr", "Stats", &F) | |||
| 2062 | << ore::NV("Function", &F) << " " | |||
| 2063 | << "Reduced the number of branches in hot paths by " | |||
| 2064 | << ore::NV("NumBranchesDelta", Stats.NumBranchesDelta) | |||
| 2065 | << " (static) and " | |||
| 2066 | << ore::NV("WeightedNumBranchesDelta", Stats.WeightedNumBranchesDelta) | |||
| 2067 | << " (weighted by PGO count)"; | |||
| 2068 | }); | |||
| 2069 | } | |||
| 2070 | ||||
| 2071 | return Changed; | |||
| 2072 | } | |||
| 2073 | ||||
| 2074 | bool ControlHeightReductionLegacyPass::runOnFunction(Function &F) { | |||
| 2075 | BlockFrequencyInfo &BFI = | |||
| 2076 | getAnalysis<BlockFrequencyInfoWrapperPass>().getBFI(); | |||
| 2077 | DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree(); | |||
| 2078 | ProfileSummaryInfo &PSI = | |||
| 2079 | getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI(); | |||
| 2080 | RegionInfo &RI = getAnalysis<RegionInfoPass>().getRegionInfo(); | |||
| 2081 | std::unique_ptr<OptimizationRemarkEmitter> OwnedORE = | |||
| 2082 | std::make_unique<OptimizationRemarkEmitter>(&F); | |||
| 2083 | return CHR(F, BFI, DT, PSI, RI, *OwnedORE.get()).run(); | |||
| 2084 | } | |||
| 2085 | ||||
| 2086 | namespace llvm { | |||
| 2087 | ||||
| 2088 | ControlHeightReductionPass::ControlHeightReductionPass() { | |||
| 2089 | parseCHRFilterFiles(); | |||
| 2090 | } | |||
| 2091 | ||||
| 2092 | PreservedAnalyses ControlHeightReductionPass::run( | |||
| 2093 | Function &F, | |||
| 2094 | FunctionAnalysisManager &FAM) { | |||
| 2095 | auto &BFI = FAM.getResult<BlockFrequencyAnalysis>(F); | |||
| 2096 | auto &DT = FAM.getResult<DominatorTreeAnalysis>(F); | |||
| 2097 | auto &MAMProxy = FAM.getResult<ModuleAnalysisManagerFunctionProxy>(F); | |||
| 2098 | auto &PSI = *MAMProxy.getCachedResult<ProfileSummaryAnalysis>(*F.getParent()); | |||
| 2099 | auto &RI = FAM.getResult<RegionInfoAnalysis>(F); | |||
| 2100 | auto &ORE = FAM.getResult<OptimizationRemarkEmitterAnalysis>(F); | |||
| 2101 | bool Changed = CHR(F, BFI, DT, PSI, RI, ORE).run(); | |||
| ||||
| 2102 | if (!Changed) | |||
| 2103 | return PreservedAnalyses::all(); | |||
| 2104 | return PreservedAnalyses::none(); | |||
| 2105 | } | |||
| 2106 | ||||
| 2107 | } // namespace llvm |