Bug Summary

File:src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
Warning:line 463, column 19
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -cc1 -triple amd64-unknown-openbsd7.0 -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name CoroSplit.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model static -mframe-pointer=all -relaxed-aliasing -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/gnu/usr.bin/clang/libLLVM/obj -resource-dir /usr/local/lib/clang/13.0.0 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Analysis -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ASMParser -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/BinaryFormat -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Bitcode -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Bitcode -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Bitstream -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /include/llvm/CodeGen -I /include/llvm/CodeGen/PBQP -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/IR -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/IR -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Coroutines -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ProfileData/Coverage -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/CodeView -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/DWARF -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/MSF -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/PDB -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Demangle -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ExecutionEngine -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ExecutionEngine/JITLink -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ExecutionEngine/Orc -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend/OpenACC -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend/OpenMP -I /include/llvm/CodeGen/GlobalISel -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/IRReader -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/InstCombine -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/Transforms/InstCombine -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/LTO -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Linker -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/MC -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/MC/MCParser -I /include/llvm/CodeGen/MIRParser -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Object -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Option -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Passes -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ProfileData -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Scalar -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ADT -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Support -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/Symbolize -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Target -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Utils -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Vectorize -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/IPO -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include -I /usr/src/gnu/usr.bin/clang/libLLVM/../include -I /usr/src/gnu/usr.bin/clang/libLLVM/obj -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include -D NDEBUG -D __STDC_LIMIT_MACROS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D LLVM_PREFIX="/usr" -internal-isystem /usr/include/c++/v1 -internal-isystem /usr/local/lib/clang/13.0.0/include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/usr/src/gnu/usr.bin/clang/libLLVM/obj -ferror-limit 19 -fvisibility-inlines-hidden -fwrapv -stack-protector 2 -fno-rtti -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /home/ben/Projects/vmm/scan-build/2022-01-12-194120-40624-1 -x c++ /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
1//===- CoroSplit.cpp - Converts a coroutine into a state machine ----------===//
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// This pass builds the coroutine frame and outlines resume and destroy parts
9// of the coroutine into separate functions.
10//
11// We present a coroutine to an LLVM as an ordinary function with suspension
12// points marked up with intrinsics. We let the optimizer party on the coroutine
13// as a single function for as long as possible. Shortly before the coroutine is
14// eligible to be inlined into its callers, we split up the coroutine into parts
15// corresponding to an initial, resume and destroy invocations of the coroutine,
16// add them to the current SCC and restart the IPO pipeline to optimize the
17// coroutine subfunctions we extracted before proceeding to the caller of the
18// coroutine.
19//===----------------------------------------------------------------------===//
20
21#include "llvm/Transforms/Coroutines/CoroSplit.h"
22#include "CoroInstr.h"
23#include "CoroInternal.h"
24#include "llvm/ADT/DenseMap.h"
25#include "llvm/ADT/SmallPtrSet.h"
26#include "llvm/ADT/SmallVector.h"
27#include "llvm/ADT/StringRef.h"
28#include "llvm/ADT/Twine.h"
29#include "llvm/Analysis/CFG.h"
30#include "llvm/Analysis/CallGraph.h"
31#include "llvm/Analysis/CallGraphSCCPass.h"
32#include "llvm/Analysis/LazyCallGraph.h"
33#include "llvm/IR/Argument.h"
34#include "llvm/IR/Attributes.h"
35#include "llvm/IR/BasicBlock.h"
36#include "llvm/IR/CFG.h"
37#include "llvm/IR/CallingConv.h"
38#include "llvm/IR/Constants.h"
39#include "llvm/IR/DataLayout.h"
40#include "llvm/IR/DerivedTypes.h"
41#include "llvm/IR/Dominators.h"
42#include "llvm/IR/Function.h"
43#include "llvm/IR/GlobalValue.h"
44#include "llvm/IR/GlobalVariable.h"
45#include "llvm/IR/IRBuilder.h"
46#include "llvm/IR/InstIterator.h"
47#include "llvm/IR/InstrTypes.h"
48#include "llvm/IR/Instruction.h"
49#include "llvm/IR/Instructions.h"
50#include "llvm/IR/IntrinsicInst.h"
51#include "llvm/IR/LLVMContext.h"
52#include "llvm/IR/LegacyPassManager.h"
53#include "llvm/IR/Module.h"
54#include "llvm/IR/Type.h"
55#include "llvm/IR/Value.h"
56#include "llvm/IR/Verifier.h"
57#include "llvm/InitializePasses.h"
58#include "llvm/Pass.h"
59#include "llvm/Support/Casting.h"
60#include "llvm/Support/Debug.h"
61#include "llvm/Support/PrettyStackTrace.h"
62#include "llvm/Support/raw_ostream.h"
63#include "llvm/Transforms/Scalar.h"
64#include "llvm/Transforms/Utils/BasicBlockUtils.h"
65#include "llvm/Transforms/Utils/CallGraphUpdater.h"
66#include "llvm/Transforms/Utils/Cloning.h"
67#include "llvm/Transforms/Utils/Local.h"
68#include "llvm/Transforms/Utils/ValueMapper.h"
69#include <cassert>
70#include <cstddef>
71#include <cstdint>
72#include <initializer_list>
73#include <iterator>
74
75using namespace llvm;
76
77#define DEBUG_TYPE"coro-split" "coro-split"
78
79namespace {
80
81/// A little helper class for building
82class CoroCloner {
83public:
84 enum class Kind {
85 /// The shared resume function for a switch lowering.
86 SwitchResume,
87
88 /// The shared unwind function for a switch lowering.
89 SwitchUnwind,
90
91 /// The shared cleanup function for a switch lowering.
92 SwitchCleanup,
93
94 /// An individual continuation function.
95 Continuation,
96
97 /// An async resume function.
98 Async,
99 };
100
101private:
102 Function &OrigF;
103 Function *NewF;
104 const Twine &Suffix;
105 coro::Shape &Shape;
106 Kind FKind;
107 ValueToValueMapTy VMap;
108 IRBuilder<> Builder;
109 Value *NewFramePtr = nullptr;
110
111 /// The active suspend instruction; meaningful only for continuation and async
112 /// ABIs.
113 AnyCoroSuspendInst *ActiveSuspend = nullptr;
14
Null pointer value stored to 'Cloner.ActiveSuspend'
114
115public:
116 /// Create a cloner for a switch lowering.
117 CoroCloner(Function &OrigF, const Twine &Suffix, coro::Shape &Shape,
118 Kind FKind)
119 : OrigF(OrigF), NewF(nullptr), Suffix(Suffix), Shape(Shape),
120 FKind(FKind), Builder(OrigF.getContext()) {
121 assert(Shape.ABI == coro::ABI::Switch)((void)0);
122 }
123
124 /// Create a cloner for a continuation lowering.
125 CoroCloner(Function &OrigF, const Twine &Suffix, coro::Shape &Shape,
126 Function *NewF, AnyCoroSuspendInst *ActiveSuspend)
127 : OrigF(OrigF), NewF(NewF), Suffix(Suffix), Shape(Shape),
128 FKind(Shape.ABI == coro::ABI::Async ? Kind::Async : Kind::Continuation),
129 Builder(OrigF.getContext()), ActiveSuspend(ActiveSuspend) {
130 assert(Shape.ABI == coro::ABI::Retcon ||((void)0)
131 Shape.ABI == coro::ABI::RetconOnce || Shape.ABI == coro::ABI::Async)((void)0);
132 assert(NewF && "need existing function for continuation")((void)0);
133 assert(ActiveSuspend && "need active suspend point for continuation")((void)0);
134 }
135
136 Function *getFunction() const {
137 assert(NewF != nullptr && "declaration not yet set")((void)0);
138 return NewF;
139 }
140
141 void create();
142
143private:
144 bool isSwitchDestroyFunction() {
145 switch (FKind) {
146 case Kind::Async:
147 case Kind::Continuation:
148 case Kind::SwitchResume:
149 return false;
150 case Kind::SwitchUnwind:
151 case Kind::SwitchCleanup:
152 return true;
153 }
154 llvm_unreachable("Unknown CoroCloner::Kind enum")__builtin_unreachable();
155 }
156
157 void replaceEntryBlock();
158 Value *deriveNewFramePointer();
159 void replaceRetconOrAsyncSuspendUses();
160 void replaceCoroSuspends();
161 void replaceCoroEnds();
162 void replaceSwiftErrorOps();
163 void salvageDebugInfo();
164 void handleFinalSuspend();
165};
166
167} // end anonymous namespace
168
169static void maybeFreeRetconStorage(IRBuilder<> &Builder,
170 const coro::Shape &Shape, Value *FramePtr,
171 CallGraph *CG) {
172 assert(Shape.ABI == coro::ABI::Retcon ||((void)0)
173 Shape.ABI == coro::ABI::RetconOnce)((void)0);
174 if (Shape.RetconLowering.IsFrameInlineInStorage)
175 return;
176
177 Shape.emitDealloc(Builder, FramePtr, CG);
178}
179
180/// Replace an llvm.coro.end.async.
181/// Will inline the must tail call function call if there is one.
182/// \returns true if cleanup of the coro.end block is needed, false otherwise.
183static bool replaceCoroEndAsync(AnyCoroEndInst *End) {
184 IRBuilder<> Builder(End);
185
186 auto *EndAsync = dyn_cast<CoroAsyncEndInst>(End);
187 if (!EndAsync) {
188 Builder.CreateRetVoid();
189 return true /*needs cleanup of coro.end block*/;
190 }
191
192 auto *MustTailCallFunc = EndAsync->getMustTailCallFunction();
193 if (!MustTailCallFunc) {
194 Builder.CreateRetVoid();
195 return true /*needs cleanup of coro.end block*/;
196 }
197
198 // Move the must tail call from the predecessor block into the end block.
199 auto *CoroEndBlock = End->getParent();
200 auto *MustTailCallFuncBlock = CoroEndBlock->getSinglePredecessor();
201 assert(MustTailCallFuncBlock && "Must have a single predecessor block")((void)0);
202 auto It = MustTailCallFuncBlock->getTerminator()->getIterator();
203 auto *MustTailCall = cast<CallInst>(&*std::prev(It));
204 CoroEndBlock->getInstList().splice(
205 End->getIterator(), MustTailCallFuncBlock->getInstList(), MustTailCall);
206
207 // Insert the return instruction.
208 Builder.SetInsertPoint(End);
209 Builder.CreateRetVoid();
210 InlineFunctionInfo FnInfo;
211
212 // Remove the rest of the block, by splitting it into an unreachable block.
213 auto *BB = End->getParent();
214 BB->splitBasicBlock(End);
215 BB->getTerminator()->eraseFromParent();
216
217 auto InlineRes = InlineFunction(*MustTailCall, FnInfo);
218 assert(InlineRes.isSuccess() && "Expected inlining to succeed")((void)0);
219 (void)InlineRes;
220
221 // We have cleaned up the coro.end block above.
222 return false;
223}
224
225/// Replace a non-unwind call to llvm.coro.end.
226static void replaceFallthroughCoroEnd(AnyCoroEndInst *End,
227 const coro::Shape &Shape, Value *FramePtr,
228 bool InResume, CallGraph *CG) {
229 // Start inserting right before the coro.end.
230 IRBuilder<> Builder(End);
231
232 // Create the return instruction.
233 switch (Shape.ABI) {
234 // The cloned functions in switch-lowering always return void.
235 case coro::ABI::Switch:
236 // coro.end doesn't immediately end the coroutine in the main function
237 // in this lowering, because we need to deallocate the coroutine.
238 if (!InResume)
239 return;
240 Builder.CreateRetVoid();
241 break;
242
243 // In async lowering this returns.
244 case coro::ABI::Async: {
245 bool CoroEndBlockNeedsCleanup = replaceCoroEndAsync(End);
246 if (!CoroEndBlockNeedsCleanup)
247 return;
248 break;
249 }
250
251 // In unique continuation lowering, the continuations always return void.
252 // But we may have implicitly allocated storage.
253 case coro::ABI::RetconOnce:
254 maybeFreeRetconStorage(Builder, Shape, FramePtr, CG);
255 Builder.CreateRetVoid();
256 break;
257
258 // In non-unique continuation lowering, we signal completion by returning
259 // a null continuation.
260 case coro::ABI::Retcon: {
261 maybeFreeRetconStorage(Builder, Shape, FramePtr, CG);
262 auto RetTy = Shape.getResumeFunctionType()->getReturnType();
263 auto RetStructTy = dyn_cast<StructType>(RetTy);
264 PointerType *ContinuationTy =
265 cast<PointerType>(RetStructTy ? RetStructTy->getElementType(0) : RetTy);
266
267 Value *ReturnValue = ConstantPointerNull::get(ContinuationTy);
268 if (RetStructTy) {
269 ReturnValue = Builder.CreateInsertValue(UndefValue::get(RetStructTy),
270 ReturnValue, 0);
271 }
272 Builder.CreateRet(ReturnValue);
273 break;
274 }
275 }
276
277 // Remove the rest of the block, by splitting it into an unreachable block.
278 auto *BB = End->getParent();
279 BB->splitBasicBlock(End);
280 BB->getTerminator()->eraseFromParent();
281}
282
283/// Replace an unwind call to llvm.coro.end.
284static void replaceUnwindCoroEnd(AnyCoroEndInst *End, const coro::Shape &Shape,
285 Value *FramePtr, bool InResume,
286 CallGraph *CG) {
287 IRBuilder<> Builder(End);
288
289 switch (Shape.ABI) {
290 // In switch-lowering, this does nothing in the main function.
291 case coro::ABI::Switch:
292 if (!InResume)
293 return;
294 break;
295 // In async lowering this does nothing.
296 case coro::ABI::Async:
297 break;
298 // In continuation-lowering, this frees the continuation storage.
299 case coro::ABI::Retcon:
300 case coro::ABI::RetconOnce:
301 maybeFreeRetconStorage(Builder, Shape, FramePtr, CG);
302 break;
303 }
304
305 // If coro.end has an associated bundle, add cleanupret instruction.
306 if (auto Bundle = End->getOperandBundle(LLVMContext::OB_funclet)) {
307 auto *FromPad = cast<CleanupPadInst>(Bundle->Inputs[0]);
308 auto *CleanupRet = Builder.CreateCleanupRet(FromPad, nullptr);
309 End->getParent()->splitBasicBlock(End);
310 CleanupRet->getParent()->getTerminator()->eraseFromParent();
311 }
312}
313
314static void replaceCoroEnd(AnyCoroEndInst *End, const coro::Shape &Shape,
315 Value *FramePtr, bool InResume, CallGraph *CG) {
316 if (End->isUnwind())
317 replaceUnwindCoroEnd(End, Shape, FramePtr, InResume, CG);
318 else
319 replaceFallthroughCoroEnd(End, Shape, FramePtr, InResume, CG);
320
321 auto &Context = End->getContext();
322 End->replaceAllUsesWith(InResume ? ConstantInt::getTrue(Context)
323 : ConstantInt::getFalse(Context));
324 End->eraseFromParent();
325}
326
327// Create an entry block for a resume function with a switch that will jump to
328// suspend points.
329static void createResumeEntryBlock(Function &F, coro::Shape &Shape) {
330 assert(Shape.ABI == coro::ABI::Switch)((void)0);
331 LLVMContext &C = F.getContext();
332
333 // resume.entry:
334 // %index.addr = getelementptr inbounds %f.Frame, %f.Frame* %FramePtr, i32 0,
335 // i32 2
336 // % index = load i32, i32* %index.addr
337 // switch i32 %index, label %unreachable [
338 // i32 0, label %resume.0
339 // i32 1, label %resume.1
340 // ...
341 // ]
342
343 auto *NewEntry = BasicBlock::Create(C, "resume.entry", &F);
344 auto *UnreachBB = BasicBlock::Create(C, "unreachable", &F);
345
346 IRBuilder<> Builder(NewEntry);
347 auto *FramePtr = Shape.FramePtr;
348 auto *FrameTy = Shape.FrameTy;
349 auto *GepIndex = Builder.CreateStructGEP(
350 FrameTy, FramePtr, Shape.getSwitchIndexField(), "index.addr");
351 auto *Index = Builder.CreateLoad(Shape.getIndexType(), GepIndex, "index");
352 auto *Switch =
353 Builder.CreateSwitch(Index, UnreachBB, Shape.CoroSuspends.size());
354 Shape.SwitchLowering.ResumeSwitch = Switch;
355
356 size_t SuspendIndex = 0;
357 for (auto *AnyS : Shape.CoroSuspends) {
358 auto *S = cast<CoroSuspendInst>(AnyS);
359 ConstantInt *IndexVal = Shape.getIndex(SuspendIndex);
360
361 // Replace CoroSave with a store to Index:
362 // %index.addr = getelementptr %f.frame... (index field number)
363 // store i32 0, i32* %index.addr1
364 auto *Save = S->getCoroSave();
365 Builder.SetInsertPoint(Save);
366 if (S->isFinal()) {
367 // Final suspend point is represented by storing zero in ResumeFnAddr.
368 auto *GepIndex = Builder.CreateStructGEP(FrameTy, FramePtr,
369 coro::Shape::SwitchFieldIndex::Resume,
370 "ResumeFn.addr");
371 auto *NullPtr = ConstantPointerNull::get(cast<PointerType>(
372 FrameTy->getTypeAtIndex(coro::Shape::SwitchFieldIndex::Resume)));
373 Builder.CreateStore(NullPtr, GepIndex);
374 } else {
375 auto *GepIndex = Builder.CreateStructGEP(
376 FrameTy, FramePtr, Shape.getSwitchIndexField(), "index.addr");
377 Builder.CreateStore(IndexVal, GepIndex);
378 }
379 Save->replaceAllUsesWith(ConstantTokenNone::get(C));
380 Save->eraseFromParent();
381
382 // Split block before and after coro.suspend and add a jump from an entry
383 // switch:
384 //
385 // whateverBB:
386 // whatever
387 // %0 = call i8 @llvm.coro.suspend(token none, i1 false)
388 // switch i8 %0, label %suspend[i8 0, label %resume
389 // i8 1, label %cleanup]
390 // becomes:
391 //
392 // whateverBB:
393 // whatever
394 // br label %resume.0.landing
395 //
396 // resume.0: ; <--- jump from the switch in the resume.entry
397 // %0 = tail call i8 @llvm.coro.suspend(token none, i1 false)
398 // br label %resume.0.landing
399 //
400 // resume.0.landing:
401 // %1 = phi i8[-1, %whateverBB], [%0, %resume.0]
402 // switch i8 % 1, label %suspend [i8 0, label %resume
403 // i8 1, label %cleanup]
404
405 auto *SuspendBB = S->getParent();
406 auto *ResumeBB =
407 SuspendBB->splitBasicBlock(S, "resume." + Twine(SuspendIndex));
408 auto *LandingBB = ResumeBB->splitBasicBlock(
409 S->getNextNode(), ResumeBB->getName() + Twine(".landing"));
410 Switch->addCase(IndexVal, ResumeBB);
411
412 cast<BranchInst>(SuspendBB->getTerminator())->setSuccessor(0, LandingBB);
413 auto *PN = PHINode::Create(Builder.getInt8Ty(), 2, "", &LandingBB->front());
414 S->replaceAllUsesWith(PN);
415 PN->addIncoming(Builder.getInt8(-1), SuspendBB);
416 PN->addIncoming(S, ResumeBB);
417
418 ++SuspendIndex;
419 }
420
421 Builder.SetInsertPoint(UnreachBB);
422 Builder.CreateUnreachable();
423
424 Shape.SwitchLowering.ResumeEntryBlock = NewEntry;
425}
426
427
428// Rewrite final suspend point handling. We do not use suspend index to
429// represent the final suspend point. Instead we zero-out ResumeFnAddr in the
430// coroutine frame, since it is undefined behavior to resume a coroutine
431// suspended at the final suspend point. Thus, in the resume function, we can
432// simply remove the last case (when coro::Shape is built, the final suspend
433// point (if present) is always the last element of CoroSuspends array).
434// In the destroy function, we add a code sequence to check if ResumeFnAddress
435// is Null, and if so, jump to the appropriate label to handle cleanup from the
436// final suspend point.
437void CoroCloner::handleFinalSuspend() {
438 assert(Shape.ABI == coro::ABI::Switch &&((void)0)
439 Shape.SwitchLowering.HasFinalSuspend)((void)0);
440 auto *Switch = cast<SwitchInst>(VMap[Shape.SwitchLowering.ResumeSwitch]);
441 auto FinalCaseIt = std::prev(Switch->case_end());
442 BasicBlock *ResumeBB = FinalCaseIt->getCaseSuccessor();
443 Switch->removeCase(FinalCaseIt);
444 if (isSwitchDestroyFunction()) {
445 BasicBlock *OldSwitchBB = Switch->getParent();
446 auto *NewSwitchBB = OldSwitchBB->splitBasicBlock(Switch, "Switch");
447 Builder.SetInsertPoint(OldSwitchBB->getTerminator());
448 auto *GepIndex = Builder.CreateStructGEP(Shape.FrameTy, NewFramePtr,
449 coro::Shape::SwitchFieldIndex::Resume,
450 "ResumeFn.addr");
451 auto *Load = Builder.CreateLoad(Shape.getSwitchResumePointerType(),
452 GepIndex);
453 auto *Cond = Builder.CreateIsNull(Load);
454 Builder.CreateCondBr(Cond, ResumeBB, NewSwitchBB);
455 OldSwitchBB->getTerminator()->eraseFromParent();
456 }
457}
458
459static FunctionType *
460getFunctionTypeFromAsyncSuspend(AnyCoroSuspendInst *Suspend) {
461 auto *AsyncSuspend = cast<CoroSuspendAsyncInst>(Suspend);
462 auto *StructTy = cast<StructType>(AsyncSuspend->getType());
25
The object is a 'StructType'
463 auto &Context = Suspend->getParent()->getParent()->getContext();
26
Called C++ object pointer is null
464 auto *VoidTy = Type::getVoidTy(Context);
465 return FunctionType::get(VoidTy, StructTy->elements(), false);
466}
467
468static Function *createCloneDeclaration(Function &OrigF, coro::Shape &Shape,
469 const Twine &Suffix,
470 Module::iterator InsertBefore,
471 AnyCoroSuspendInst *ActiveSuspend) {
472 Module *M = OrigF.getParent();
473 auto *FnTy = (Shape.ABI != coro::ABI::Async)
21
Assuming field 'ABI' is equal to Async
22
'?' condition is false
474 ? Shape.getResumeFunctionType()
475 : getFunctionTypeFromAsyncSuspend(ActiveSuspend);
23
Passing null pointer value via 1st parameter 'Suspend'
24
Calling 'getFunctionTypeFromAsyncSuspend'
476
477 Function *NewF =
478 Function::Create(FnTy, GlobalValue::LinkageTypes::InternalLinkage,
479 OrigF.getName() + Suffix);
480 if (Shape.ABI != coro::ABI::Async)
481 NewF->addParamAttr(0, Attribute::NonNull);
482
483 // For the async lowering ABI we can't guarantee that the context argument is
484 // not access via a different pointer not based on the argument.
485 if (Shape.ABI != coro::ABI::Async)
486 NewF->addParamAttr(0, Attribute::NoAlias);
487
488 M->getFunctionList().insert(InsertBefore, NewF);
489
490 return NewF;
491}
492
493/// Replace uses of the active llvm.coro.suspend.retcon/async call with the
494/// arguments to the continuation function.
495///
496/// This assumes that the builder has a meaningful insertion point.
497void CoroCloner::replaceRetconOrAsyncSuspendUses() {
498 assert(Shape.ABI == coro::ABI::Retcon || Shape.ABI == coro::ABI::RetconOnce ||((void)0)
499 Shape.ABI == coro::ABI::Async)((void)0);
500
501 auto NewS = VMap[ActiveSuspend];
502 if (NewS->use_empty()) return;
503
504 // Copy out all the continuation arguments after the buffer pointer into
505 // an easily-indexed data structure for convenience.
506 SmallVector<Value*, 8> Args;
507 // The async ABI includes all arguments -- including the first argument.
508 bool IsAsyncABI = Shape.ABI == coro::ABI::Async;
509 for (auto I = IsAsyncABI ? NewF->arg_begin() : std::next(NewF->arg_begin()),
510 E = NewF->arg_end();
511 I != E; ++I)
512 Args.push_back(&*I);
513
514 // If the suspend returns a single scalar value, we can just do a simple
515 // replacement.
516 if (!isa<StructType>(NewS->getType())) {
517 assert(Args.size() == 1)((void)0);
518 NewS->replaceAllUsesWith(Args.front());
519 return;
520 }
521
522 // Try to peephole extracts of an aggregate return.
523 for (auto UI = NewS->use_begin(), UE = NewS->use_end(); UI != UE; ) {
524 auto EVI = dyn_cast<ExtractValueInst>((UI++)->getUser());
525 if (!EVI || EVI->getNumIndices() != 1)
526 continue;
527
528 EVI->replaceAllUsesWith(Args[EVI->getIndices().front()]);
529 EVI->eraseFromParent();
530 }
531
532 // If we have no remaining uses, we're done.
533 if (NewS->use_empty()) return;
534
535 // Otherwise, we need to create an aggregate.
536 Value *Agg = UndefValue::get(NewS->getType());
537 for (size_t I = 0, E = Args.size(); I != E; ++I)
538 Agg = Builder.CreateInsertValue(Agg, Args[I], I);
539
540 NewS->replaceAllUsesWith(Agg);
541}
542
543void CoroCloner::replaceCoroSuspends() {
544 Value *SuspendResult;
545
546 switch (Shape.ABI) {
547 // In switch lowering, replace coro.suspend with the appropriate value
548 // for the type of function we're extracting.
549 // Replacing coro.suspend with (0) will result in control flow proceeding to
550 // a resume label associated with a suspend point, replacing it with (1) will
551 // result in control flow proceeding to a cleanup label associated with this
552 // suspend point.
553 case coro::ABI::Switch:
554 SuspendResult = Builder.getInt8(isSwitchDestroyFunction() ? 1 : 0);
555 break;
556
557 // In async lowering there are no uses of the result.
558 case coro::ABI::Async:
559 return;
560
561 // In returned-continuation lowering, the arguments from earlier
562 // continuations are theoretically arbitrary, and they should have been
563 // spilled.
564 case coro::ABI::RetconOnce:
565 case coro::ABI::Retcon:
566 return;
567 }
568
569 for (AnyCoroSuspendInst *CS : Shape.CoroSuspends) {
570 // The active suspend was handled earlier.
571 if (CS == ActiveSuspend) continue;
572
573 auto *MappedCS = cast<AnyCoroSuspendInst>(VMap[CS]);
574 MappedCS->replaceAllUsesWith(SuspendResult);
575 MappedCS->eraseFromParent();
576 }
577}
578
579void CoroCloner::replaceCoroEnds() {
580 for (AnyCoroEndInst *CE : Shape.CoroEnds) {
581 // We use a null call graph because there's no call graph node for
582 // the cloned function yet. We'll just be rebuilding that later.
583 auto *NewCE = cast<AnyCoroEndInst>(VMap[CE]);
584 replaceCoroEnd(NewCE, Shape, NewFramePtr, /*in resume*/ true, nullptr);
585 }
586}
587
588static void replaceSwiftErrorOps(Function &F, coro::Shape &Shape,
589 ValueToValueMapTy *VMap) {
590 if (Shape.ABI == coro::ABI::Async && Shape.CoroSuspends.empty())
591 return;
592 Value *CachedSlot = nullptr;
593 auto getSwiftErrorSlot = [&](Type *ValueTy) -> Value * {
594 if (CachedSlot) {
595 assert(CachedSlot->getType()->getPointerElementType() == ValueTy &&((void)0)
596 "multiple swifterror slots in function with different types")((void)0);
597 return CachedSlot;
598 }
599
600 // Check if the function has a swifterror argument.
601 for (auto &Arg : F.args()) {
602 if (Arg.isSwiftError()) {
603 CachedSlot = &Arg;
604 assert(Arg.getType()->getPointerElementType() == ValueTy &&((void)0)
605 "swifterror argument does not have expected type")((void)0);
606 return &Arg;
607 }
608 }
609
610 // Create a swifterror alloca.
611 IRBuilder<> Builder(F.getEntryBlock().getFirstNonPHIOrDbg());
612 auto Alloca = Builder.CreateAlloca(ValueTy);
613 Alloca->setSwiftError(true);
614
615 CachedSlot = Alloca;
616 return Alloca;
617 };
618
619 for (CallInst *Op : Shape.SwiftErrorOps) {
620 auto MappedOp = VMap ? cast<CallInst>((*VMap)[Op]) : Op;
621 IRBuilder<> Builder(MappedOp);
622
623 // If there are no arguments, this is a 'get' operation.
624 Value *MappedResult;
625 if (Op->getNumArgOperands() == 0) {
626 auto ValueTy = Op->getType();
627 auto Slot = getSwiftErrorSlot(ValueTy);
628 MappedResult = Builder.CreateLoad(ValueTy, Slot);
629 } else {
630 assert(Op->getNumArgOperands() == 1)((void)0);
631 auto Value = MappedOp->getArgOperand(0);
632 auto ValueTy = Value->getType();
633 auto Slot = getSwiftErrorSlot(ValueTy);
634 Builder.CreateStore(Value, Slot);
635 MappedResult = Slot;
636 }
637
638 MappedOp->replaceAllUsesWith(MappedResult);
639 MappedOp->eraseFromParent();
640 }
641
642 // If we're updating the original function, we've invalidated SwiftErrorOps.
643 if (VMap == nullptr) {
644 Shape.SwiftErrorOps.clear();
645 }
646}
647
648void CoroCloner::replaceSwiftErrorOps() {
649 ::replaceSwiftErrorOps(*NewF, Shape, &VMap);
650}
651
652void CoroCloner::salvageDebugInfo() {
653 SmallVector<DbgVariableIntrinsic *, 8> Worklist;
654 SmallDenseMap<llvm::Value *, llvm::AllocaInst *, 4> DbgPtrAllocaCache;
655 for (auto &BB : *NewF)
656 for (auto &I : BB)
657 if (auto *DVI = dyn_cast<DbgVariableIntrinsic>(&I))
658 Worklist.push_back(DVI);
659 for (DbgVariableIntrinsic *DVI : Worklist)
660 coro::salvageDebugInfo(DbgPtrAllocaCache, DVI, Shape.ReuseFrameSlot);
661
662 // Remove all salvaged dbg.declare intrinsics that became
663 // either unreachable or stale due to the CoroSplit transformation.
664 DominatorTree DomTree(*NewF);
665 auto IsUnreachableBlock = [&](BasicBlock *BB) {
666 return !isPotentiallyReachable(&NewF->getEntryBlock(), BB, nullptr,
667 &DomTree);
668 };
669 for (DbgVariableIntrinsic *DVI : Worklist) {
670 if (IsUnreachableBlock(DVI->getParent()))
671 DVI->eraseFromParent();
672 else if (dyn_cast_or_null<AllocaInst>(DVI->getVariableLocationOp(0))) {
673 // Count all non-debuginfo uses in reachable blocks.
674 unsigned Uses = 0;
675 for (auto *User : DVI->getVariableLocationOp(0)->users())
676 if (auto *I = dyn_cast<Instruction>(User))
677 if (!isa<AllocaInst>(I) && !IsUnreachableBlock(I->getParent()))
678 ++Uses;
679 if (!Uses)
680 DVI->eraseFromParent();
681 }
682 }
683}
684
685void CoroCloner::replaceEntryBlock() {
686 // In the original function, the AllocaSpillBlock is a block immediately
687 // following the allocation of the frame object which defines GEPs for
688 // all the allocas that have been moved into the frame, and it ends by
689 // branching to the original beginning of the coroutine. Make this
690 // the entry block of the cloned function.
691 auto *Entry = cast<BasicBlock>(VMap[Shape.AllocaSpillBlock]);
692 auto *OldEntry = &NewF->getEntryBlock();
693 Entry->setName("entry" + Suffix);
694 Entry->moveBefore(OldEntry);
695 Entry->getTerminator()->eraseFromParent();
696
697 // Clear all predecessors of the new entry block. There should be
698 // exactly one predecessor, which we created when splitting out
699 // AllocaSpillBlock to begin with.
700 assert(Entry->hasOneUse())((void)0);
701 auto BranchToEntry = cast<BranchInst>(Entry->user_back());
702 assert(BranchToEntry->isUnconditional())((void)0);
703 Builder.SetInsertPoint(BranchToEntry);
704 Builder.CreateUnreachable();
705 BranchToEntry->eraseFromParent();
706
707 // Branch from the entry to the appropriate place.
708 Builder.SetInsertPoint(Entry);
709 switch (Shape.ABI) {
710 case coro::ABI::Switch: {
711 // In switch-lowering, we built a resume-entry block in the original
712 // function. Make the entry block branch to this.
713 auto *SwitchBB =
714 cast<BasicBlock>(VMap[Shape.SwitchLowering.ResumeEntryBlock]);
715 Builder.CreateBr(SwitchBB);
716 break;
717 }
718 case coro::ABI::Async:
719 case coro::ABI::Retcon:
720 case coro::ABI::RetconOnce: {
721 // In continuation ABIs, we want to branch to immediately after the
722 // active suspend point. Earlier phases will have put the suspend in its
723 // own basic block, so just thread our jump directly to its successor.
724 assert((Shape.ABI == coro::ABI::Async &&((void)0)
725 isa<CoroSuspendAsyncInst>(ActiveSuspend)) ||((void)0)
726 ((Shape.ABI == coro::ABI::Retcon ||((void)0)
727 Shape.ABI == coro::ABI::RetconOnce) &&((void)0)
728 isa<CoroSuspendRetconInst>(ActiveSuspend)))((void)0);
729 auto *MappedCS = cast<AnyCoroSuspendInst>(VMap[ActiveSuspend]);
730 auto Branch = cast<BranchInst>(MappedCS->getNextNode());
731 assert(Branch->isUnconditional())((void)0);
732 Builder.CreateBr(Branch->getSuccessor(0));
733 break;
734 }
735 }
736
737 // Any static alloca that's still being used but not reachable from the new
738 // entry needs to be moved to the new entry.
739 Function *F = OldEntry->getParent();
740 DominatorTree DT{*F};
741 for (auto IT = inst_begin(F), End = inst_end(F); IT != End;) {
742 Instruction &I = *IT++;
743 auto *Alloca = dyn_cast<AllocaInst>(&I);
744 if (!Alloca || I.use_empty())
745 continue;
746 if (DT.isReachableFromEntry(I.getParent()) ||
747 !isa<ConstantInt>(Alloca->getArraySize()))
748 continue;
749 I.moveBefore(*Entry, Entry->getFirstInsertionPt());
750 }
751}
752
753/// Derive the value of the new frame pointer.
754Value *CoroCloner::deriveNewFramePointer() {
755 // Builder should be inserting to the front of the new entry block.
756
757 switch (Shape.ABI) {
758 // In switch-lowering, the argument is the frame pointer.
759 case coro::ABI::Switch:
760 return &*NewF->arg_begin();
761 // In async-lowering, one of the arguments is an async context as determined
762 // by the `llvm.coro.id.async` intrinsic. We can retrieve the async context of
763 // the resume function from the async context projection function associated
764 // with the active suspend. The frame is located as a tail to the async
765 // context header.
766 case coro::ABI::Async: {
767 auto *ActiveAsyncSuspend = cast<CoroSuspendAsyncInst>(ActiveSuspend);
768 auto ContextIdx = ActiveAsyncSuspend->getStorageArgumentIndex() & 0xff;
769 auto *CalleeContext = NewF->getArg(ContextIdx);
770 auto *FramePtrTy = Shape.FrameTy->getPointerTo();
771 auto *ProjectionFunc =
772 ActiveAsyncSuspend->getAsyncContextProjectionFunction();
773 auto DbgLoc =
774 cast<CoroSuspendAsyncInst>(VMap[ActiveSuspend])->getDebugLoc();
775 // Calling i8* (i8*)
776 auto *CallerContext = Builder.CreateCall(
777 cast<FunctionType>(ProjectionFunc->getType()->getPointerElementType()),
778 ProjectionFunc, CalleeContext);
779 CallerContext->setCallingConv(ProjectionFunc->getCallingConv());
780 CallerContext->setDebugLoc(DbgLoc);
781 // The frame is located after the async_context header.
782 auto &Context = Builder.getContext();
783 auto *FramePtrAddr = Builder.CreateConstInBoundsGEP1_32(
784 Type::getInt8Ty(Context), CallerContext,
785 Shape.AsyncLowering.FrameOffset, "async.ctx.frameptr");
786 // Inline the projection function.
787 InlineFunctionInfo InlineInfo;
788 auto InlineRes = InlineFunction(*CallerContext, InlineInfo);
789 assert(InlineRes.isSuccess())((void)0);
790 (void)InlineRes;
791 return Builder.CreateBitCast(FramePtrAddr, FramePtrTy);
792 }
793 // In continuation-lowering, the argument is the opaque storage.
794 case coro::ABI::Retcon:
795 case coro::ABI::RetconOnce: {
796 Argument *NewStorage = &*NewF->arg_begin();
797 auto FramePtrTy = Shape.FrameTy->getPointerTo();
798
799 // If the storage is inline, just bitcast to the storage to the frame type.
800 if (Shape.RetconLowering.IsFrameInlineInStorage)
801 return Builder.CreateBitCast(NewStorage, FramePtrTy);
802
803 // Otherwise, load the real frame from the opaque storage.
804 auto FramePtrPtr =
805 Builder.CreateBitCast(NewStorage, FramePtrTy->getPointerTo());
806 return Builder.CreateLoad(FramePtrTy, FramePtrPtr);
807 }
808 }
809 llvm_unreachable("bad ABI")__builtin_unreachable();
810}
811
812static void addFramePointerAttrs(AttributeList &Attrs, LLVMContext &Context,
813 unsigned ParamIndex,
814 uint64_t Size, Align Alignment) {
815 AttrBuilder ParamAttrs;
816 ParamAttrs.addAttribute(Attribute::NonNull);
817 ParamAttrs.addAttribute(Attribute::NoAlias);
818 ParamAttrs.addAlignmentAttr(Alignment);
819 ParamAttrs.addDereferenceableAttr(Size);
820 Attrs = Attrs.addParamAttributes(Context, ParamIndex, ParamAttrs);
821}
822
823static void addAsyncContextAttrs(AttributeList &Attrs, LLVMContext &Context,
824 unsigned ParamIndex) {
825 AttrBuilder ParamAttrs;
826 ParamAttrs.addAttribute(Attribute::SwiftAsync);
827 Attrs = Attrs.addParamAttributes(Context, ParamIndex, ParamAttrs);
828}
829
830static void addSwiftSelfAttrs(AttributeList &Attrs, LLVMContext &Context,
831 unsigned ParamIndex) {
832 AttrBuilder ParamAttrs;
833 ParamAttrs.addAttribute(Attribute::SwiftSelf);
834 Attrs = Attrs.addParamAttributes(Context, ParamIndex, ParamAttrs);
835}
836
837/// Clone the body of the original function into a resume function of
838/// some sort.
839void CoroCloner::create() {
840 // Create the new function if we don't already have one.
841 if (!NewF) {
17
Assuming field 'NewF' is null
18
Taking true branch
842 NewF = createCloneDeclaration(OrigF, Shape, Suffix,
20
Calling 'createCloneDeclaration'
843 OrigF.getParent()->end(), ActiveSuspend);
19
Passing null pointer value via 5th parameter 'ActiveSuspend'
844 }
845
846 // Replace all args with undefs. The buildCoroutineFrame algorithm already
847 // rewritten access to the args that occurs after suspend points with loads
848 // and stores to/from the coroutine frame.
849 for (Argument &A : OrigF.args())
850 VMap[&A] = UndefValue::get(A.getType());
851
852 SmallVector<ReturnInst *, 4> Returns;
853
854 // Ignore attempts to change certain attributes of the function.
855 // TODO: maybe there should be a way to suppress this during cloning?
856 auto savedVisibility = NewF->getVisibility();
857 auto savedUnnamedAddr = NewF->getUnnamedAddr();
858 auto savedDLLStorageClass = NewF->getDLLStorageClass();
859
860 // NewF's linkage (which CloneFunctionInto does *not* change) might not
861 // be compatible with the visibility of OrigF (which it *does* change),
862 // so protect against that.
863 auto savedLinkage = NewF->getLinkage();
864 NewF->setLinkage(llvm::GlobalValue::ExternalLinkage);
865
866 CloneFunctionInto(NewF, &OrigF, VMap,
867 CloneFunctionChangeType::LocalChangesOnly, Returns);
868
869 auto &Context = NewF->getContext();
870
871 // For async functions / continuations, adjust the scope line of the
872 // clone to the line number of the suspend point. However, only
873 // adjust the scope line when the files are the same. This ensures
874 // line number and file name belong together. The scope line is
875 // associated with all pre-prologue instructions. This avoids a jump
876 // in the linetable from the function declaration to the suspend point.
877 if (DISubprogram *SP = NewF->getSubprogram()) {
878 assert(SP != OrigF.getSubprogram() && SP->isDistinct())((void)0);
879 if (ActiveSuspend)
880 if (auto DL = ActiveSuspend->getDebugLoc())
881 if (SP->getFile() == DL->getFile())
882 SP->setScopeLine(DL->getLine());
883 // Update the linkage name to reflect the modified symbol name. It
884 // is necessary to update the linkage name in Swift, since the
885 // mangling changes for resume functions. It might also be the
886 // right thing to do in C++, but due to a limitation in LLVM's
887 // AsmPrinter we can only do this if the function doesn't have an
888 // abstract specification, since the DWARF backend expects the
889 // abstract specification to contain the linkage name and asserts
890 // that they are identical.
891 if (!SP->getDeclaration() && SP->getUnit() &&
892 SP->getUnit()->getSourceLanguage() == dwarf::DW_LANG_Swift)
893 SP->replaceLinkageName(MDString::get(Context, NewF->getName()));
894 }
895
896 NewF->setLinkage(savedLinkage);
897 NewF->setVisibility(savedVisibility);
898 NewF->setUnnamedAddr(savedUnnamedAddr);
899 NewF->setDLLStorageClass(savedDLLStorageClass);
900
901 // Replace the attributes of the new function:
902 auto OrigAttrs = NewF->getAttributes();
903 auto NewAttrs = AttributeList();
904
905 switch (Shape.ABI) {
906 case coro::ABI::Switch:
907 // Bootstrap attributes by copying function attributes from the
908 // original function. This should include optimization settings and so on.
909 NewAttrs = NewAttrs.addAttributes(Context, AttributeList::FunctionIndex,
910 OrigAttrs.getFnAttributes());
911
912 addFramePointerAttrs(NewAttrs, Context, 0,
913 Shape.FrameSize, Shape.FrameAlign);
914 break;
915 case coro::ABI::Async: {
916 auto *ActiveAsyncSuspend = cast<CoroSuspendAsyncInst>(ActiveSuspend);
917 if (OrigF.hasParamAttribute(Shape.AsyncLowering.ContextArgNo,
918 Attribute::SwiftAsync)) {
919 uint32_t ArgAttributeIndices =
920 ActiveAsyncSuspend->getStorageArgumentIndex();
921 auto ContextArgIndex = ArgAttributeIndices & 0xff;
922 addAsyncContextAttrs(NewAttrs, Context, ContextArgIndex);
923
924 // `swiftasync` must preceed `swiftself` so 0 is not a valid index for
925 // `swiftself`.
926 auto SwiftSelfIndex = ArgAttributeIndices >> 8;
927 if (SwiftSelfIndex)
928 addSwiftSelfAttrs(NewAttrs, Context, SwiftSelfIndex);
929 }
930
931 // Transfer the original function's attributes.
932 auto FnAttrs = OrigF.getAttributes().getFnAttributes();
933 NewAttrs =
934 NewAttrs.addAttributes(Context, AttributeList::FunctionIndex, FnAttrs);
935 break;
936 }
937 case coro::ABI::Retcon:
938 case coro::ABI::RetconOnce:
939 // If we have a continuation prototype, just use its attributes,
940 // full-stop.
941 NewAttrs = Shape.RetconLowering.ResumePrototype->getAttributes();
942
943 addFramePointerAttrs(NewAttrs, Context, 0,
944 Shape.getRetconCoroId()->getStorageSize(),
945 Shape.getRetconCoroId()->getStorageAlignment());
946 break;
947 }
948
949 switch (Shape.ABI) {
950 // In these ABIs, the cloned functions always return 'void', and the
951 // existing return sites are meaningless. Note that for unique
952 // continuations, this includes the returns associated with suspends;
953 // this is fine because we can't suspend twice.
954 case coro::ABI::Switch:
955 case coro::ABI::RetconOnce:
956 // Remove old returns.
957 for (ReturnInst *Return : Returns)
958 changeToUnreachable(Return);
959 break;
960
961 // With multi-suspend continuations, we'll already have eliminated the
962 // original returns and inserted returns before all the suspend points,
963 // so we want to leave any returns in place.
964 case coro::ABI::Retcon:
965 break;
966 // Async lowering will insert musttail call functions at all suspend points
967 // followed by a return.
968 // Don't change returns to unreachable because that will trip up the verifier.
969 // These returns should be unreachable from the clone.
970 case coro::ABI::Async:
971 break;
972 }
973
974 NewF->setAttributes(NewAttrs);
975 NewF->setCallingConv(Shape.getResumeFunctionCC());
976
977 // Set up the new entry block.
978 replaceEntryBlock();
979
980 Builder.SetInsertPoint(&NewF->getEntryBlock().front());
981 NewFramePtr = deriveNewFramePointer();
982
983 // Remap frame pointer.
984 Value *OldFramePtr = VMap[Shape.FramePtr];
985 NewFramePtr->takeName(OldFramePtr);
986 OldFramePtr->replaceAllUsesWith(NewFramePtr);
987
988 // Remap vFrame pointer.
989 auto *NewVFrame = Builder.CreateBitCast(
990 NewFramePtr, Type::getInt8PtrTy(Builder.getContext()), "vFrame");
991 Value *OldVFrame = cast<Value>(VMap[Shape.CoroBegin]);
992 OldVFrame->replaceAllUsesWith(NewVFrame);
993
994 switch (Shape.ABI) {
995 case coro::ABI::Switch:
996 // Rewrite final suspend handling as it is not done via switch (allows to
997 // remove final case from the switch, since it is undefined behavior to
998 // resume the coroutine suspended at the final suspend point.
999 if (Shape.SwitchLowering.HasFinalSuspend)
1000 handleFinalSuspend();
1001 break;
1002 case coro::ABI::Async:
1003 case coro::ABI::Retcon:
1004 case coro::ABI::RetconOnce:
1005 // Replace uses of the active suspend with the corresponding
1006 // continuation-function arguments.
1007 assert(ActiveSuspend != nullptr &&((void)0)
1008 "no active suspend when lowering a continuation-style coroutine")((void)0);
1009 replaceRetconOrAsyncSuspendUses();
1010 break;
1011 }
1012
1013 // Handle suspends.
1014 replaceCoroSuspends();
1015
1016 // Handle swifterror.
1017 replaceSwiftErrorOps();
1018
1019 // Remove coro.end intrinsics.
1020 replaceCoroEnds();
1021
1022 // Salvage debug info that points into the coroutine frame.
1023 salvageDebugInfo();
1024
1025 // Eliminate coro.free from the clones, replacing it with 'null' in cleanup,
1026 // to suppress deallocation code.
1027 if (Shape.ABI == coro::ABI::Switch)
1028 coro::replaceCoroFree(cast<CoroIdInst>(VMap[Shape.CoroBegin->getId()]),
1029 /*Elide=*/ FKind == CoroCloner::Kind::SwitchCleanup);
1030}
1031
1032// Create a resume clone by cloning the body of the original function, setting
1033// new entry block and replacing coro.suspend an appropriate value to force
1034// resume or cleanup pass for every suspend point.
1035static Function *createClone(Function &F, const Twine &Suffix,
1036 coro::Shape &Shape, CoroCloner::Kind FKind) {
1037 CoroCloner Cloner(F, Suffix, Shape, FKind);
13
Calling constructor for 'CoroCloner'
15
Returning from constructor for 'CoroCloner'
1038 Cloner.create();
16
Calling 'CoroCloner::create'
1039 return Cloner.getFunction();
1040}
1041
1042/// Remove calls to llvm.coro.end in the original function.
1043static void removeCoroEnds(const coro::Shape &Shape, CallGraph *CG) {
1044 for (auto End : Shape.CoroEnds) {
1045 replaceCoroEnd(End, Shape, Shape.FramePtr, /*in resume*/ false, CG);
1046 }
1047}
1048
1049static void updateAsyncFuncPointerContextSize(coro::Shape &Shape) {
1050 assert(Shape.ABI == coro::ABI::Async)((void)0);
1051
1052 auto *FuncPtrStruct = cast<ConstantStruct>(
1053 Shape.AsyncLowering.AsyncFuncPointer->getInitializer());
1054 auto *OrigRelativeFunOffset = FuncPtrStruct->getOperand(0);
1055 auto *OrigContextSize = FuncPtrStruct->getOperand(1);
1056 auto *NewContextSize = ConstantInt::get(OrigContextSize->getType(),
1057 Shape.AsyncLowering.ContextSize);
1058 auto *NewFuncPtrStruct = ConstantStruct::get(
1059 FuncPtrStruct->getType(), OrigRelativeFunOffset, NewContextSize);
1060
1061 Shape.AsyncLowering.AsyncFuncPointer->setInitializer(NewFuncPtrStruct);
1062}
1063
1064static void replaceFrameSize(coro::Shape &Shape) {
1065 if (Shape.ABI == coro::ABI::Async)
1066 updateAsyncFuncPointerContextSize(Shape);
1067
1068 if (Shape.CoroSizes.empty())
1069 return;
1070
1071 // In the same function all coro.sizes should have the same result type.
1072 auto *SizeIntrin = Shape.CoroSizes.back();
1073 Module *M = SizeIntrin->getModule();
1074 const DataLayout &DL = M->getDataLayout();
1075 auto Size = DL.getTypeAllocSize(Shape.FrameTy);
1076 auto *SizeConstant = ConstantInt::get(SizeIntrin->getType(), Size);
1077
1078 for (CoroSizeInst *CS : Shape.CoroSizes) {
1079 CS->replaceAllUsesWith(SizeConstant);
1080 CS->eraseFromParent();
1081 }
1082}
1083
1084// Create a global constant array containing pointers to functions provided and
1085// set Info parameter of CoroBegin to point at this constant. Example:
1086//
1087// @f.resumers = internal constant [2 x void(%f.frame*)*]
1088// [void(%f.frame*)* @f.resume, void(%f.frame*)* @f.destroy]
1089// define void @f() {
1090// ...
1091// call i8* @llvm.coro.begin(i8* null, i32 0, i8* null,
1092// i8* bitcast([2 x void(%f.frame*)*] * @f.resumers to i8*))
1093//
1094// Assumes that all the functions have the same signature.
1095static void setCoroInfo(Function &F, coro::Shape &Shape,
1096 ArrayRef<Function *> Fns) {
1097 // This only works under the switch-lowering ABI because coro elision
1098 // only works on the switch-lowering ABI.
1099 assert(Shape.ABI == coro::ABI::Switch)((void)0);
1100
1101 SmallVector<Constant *, 4> Args(Fns.begin(), Fns.end());
1102 assert(!Args.empty())((void)0);
1103 Function *Part = *Fns.begin();
1104 Module *M = Part->getParent();
1105 auto *ArrTy = ArrayType::get(Part->getType(), Args.size());
1106
1107 auto *ConstVal = ConstantArray::get(ArrTy, Args);
1108 auto *GV = new GlobalVariable(*M, ConstVal->getType(), /*isConstant=*/true,
1109 GlobalVariable::PrivateLinkage, ConstVal,
1110 F.getName() + Twine(".resumers"));
1111
1112 // Update coro.begin instruction to refer to this constant.
1113 LLVMContext &C = F.getContext();
1114 auto *BC = ConstantExpr::getPointerCast(GV, Type::getInt8PtrTy(C));
1115 Shape.getSwitchCoroId()->setInfo(BC);
1116}
1117
1118// Store addresses of Resume/Destroy/Cleanup functions in the coroutine frame.
1119static void updateCoroFrame(coro::Shape &Shape, Function *ResumeFn,
1120 Function *DestroyFn, Function *CleanupFn) {
1121 assert(Shape.ABI == coro::ABI::Switch)((void)0);
1122
1123 IRBuilder<> Builder(Shape.FramePtr->getNextNode());
1124 auto *ResumeAddr = Builder.CreateStructGEP(
1125 Shape.FrameTy, Shape.FramePtr, coro::Shape::SwitchFieldIndex::Resume,
1126 "resume.addr");
1127 Builder.CreateStore(ResumeFn, ResumeAddr);
1128
1129 Value *DestroyOrCleanupFn = DestroyFn;
1130
1131 CoroIdInst *CoroId = Shape.getSwitchCoroId();
1132 if (CoroAllocInst *CA = CoroId->getCoroAlloc()) {
1133 // If there is a CoroAlloc and it returns false (meaning we elide the
1134 // allocation, use CleanupFn instead of DestroyFn).
1135 DestroyOrCleanupFn = Builder.CreateSelect(CA, DestroyFn, CleanupFn);
1136 }
1137
1138 auto *DestroyAddr = Builder.CreateStructGEP(
1139 Shape.FrameTy, Shape.FramePtr, coro::Shape::SwitchFieldIndex::Destroy,
1140 "destroy.addr");
1141 Builder.CreateStore(DestroyOrCleanupFn, DestroyAddr);
1142}
1143
1144static void postSplitCleanup(Function &F) {
1145 removeUnreachableBlocks(F);
1146
1147 // For now, we do a mandatory verification step because we don't
1148 // entirely trust this pass. Note that we don't want to add a verifier
1149 // pass to FPM below because it will also verify all the global data.
1150 if (verifyFunction(F, &errs()))
1151 report_fatal_error("Broken function");
1152}
1153
1154// Assuming we arrived at the block NewBlock from Prev instruction, store
1155// PHI's incoming values in the ResolvedValues map.
1156static void
1157scanPHIsAndUpdateValueMap(Instruction *Prev, BasicBlock *NewBlock,
1158 DenseMap<Value *, Value *> &ResolvedValues) {
1159 auto *PrevBB = Prev->getParent();
1160 for (PHINode &PN : NewBlock->phis()) {
1161 auto V = PN.getIncomingValueForBlock(PrevBB);
1162 // See if we already resolved it.
1163 auto VI = ResolvedValues.find(V);
1164 if (VI != ResolvedValues.end())
1165 V = VI->second;
1166 // Remember the value.
1167 ResolvedValues[&PN] = V;
1168 }
1169}
1170
1171// Replace a sequence of branches leading to a ret, with a clone of a ret
1172// instruction. Suspend instruction represented by a switch, track the PHI
1173// values and select the correct case successor when possible.
1174static bool simplifyTerminatorLeadingToRet(Instruction *InitialInst) {
1175 DenseMap<Value *, Value *> ResolvedValues;
1176 BasicBlock *UnconditionalSucc = nullptr;
1177
1178 Instruction *I = InitialInst;
1179 while (I->isTerminator() ||
1180 (isa<CmpInst>(I) && I->getNextNode()->isTerminator())) {
1181 if (isa<ReturnInst>(I)) {
1182 if (I != InitialInst) {
1183 // If InitialInst is an unconditional branch,
1184 // remove PHI values that come from basic block of InitialInst
1185 if (UnconditionalSucc)
1186 UnconditionalSucc->removePredecessor(InitialInst->getParent(), true);
1187 ReplaceInstWithInst(InitialInst, I->clone());
1188 }
1189 return true;
1190 }
1191 if (auto *BR = dyn_cast<BranchInst>(I)) {
1192 if (BR->isUnconditional()) {
1193 BasicBlock *BB = BR->getSuccessor(0);
1194 if (I == InitialInst)
1195 UnconditionalSucc = BB;
1196 scanPHIsAndUpdateValueMap(I, BB, ResolvedValues);
1197 I = BB->getFirstNonPHIOrDbgOrLifetime();
1198 continue;
1199 }
1200 } else if (auto *CondCmp = dyn_cast<CmpInst>(I)) {
1201 auto *BR = dyn_cast<BranchInst>(I->getNextNode());
1202 if (BR && BR->isConditional() && CondCmp == BR->getCondition()) {
1203 // If the case number of suspended switch instruction is reduced to
1204 // 1, then it is simplified to CmpInst in llvm::ConstantFoldTerminator.
1205 // And the comparsion looks like : %cond = icmp eq i8 %V, constant.
1206 ConstantInt *CondConst = dyn_cast<ConstantInt>(CondCmp->getOperand(1));
1207 if (CondConst && CondCmp->getPredicate() == CmpInst::ICMP_EQ) {
1208 Value *V = CondCmp->getOperand(0);
1209 auto it = ResolvedValues.find(V);
1210 if (it != ResolvedValues.end())
1211 V = it->second;
1212
1213 if (ConstantInt *Cond0 = dyn_cast<ConstantInt>(V)) {
1214 BasicBlock *BB = Cond0->equalsInt(CondConst->getZExtValue())
1215 ? BR->getSuccessor(0)
1216 : BR->getSuccessor(1);
1217 scanPHIsAndUpdateValueMap(I, BB, ResolvedValues);
1218 I = BB->getFirstNonPHIOrDbgOrLifetime();
1219 continue;
1220 }
1221 }
1222 }
1223 } else if (auto *SI = dyn_cast<SwitchInst>(I)) {
1224 Value *V = SI->getCondition();
1225 auto it = ResolvedValues.find(V);
1226 if (it != ResolvedValues.end())
1227 V = it->second;
1228 if (ConstantInt *Cond = dyn_cast<ConstantInt>(V)) {
1229 BasicBlock *BB = SI->findCaseValue(Cond)->getCaseSuccessor();
1230 scanPHIsAndUpdateValueMap(I, BB, ResolvedValues);
1231 I = BB->getFirstNonPHIOrDbgOrLifetime();
1232 continue;
1233 }
1234 }
1235 return false;
1236 }
1237 return false;
1238}
1239
1240// Check whether CI obeys the rules of musttail attribute.
1241static bool shouldBeMustTail(const CallInst &CI, const Function &F) {
1242 if (CI.isInlineAsm())
1243 return false;
1244
1245 // Match prototypes and calling conventions of resume function.
1246 FunctionType *CalleeTy = CI.getFunctionType();
1247 if (!CalleeTy->getReturnType()->isVoidTy() || (CalleeTy->getNumParams() != 1))
1248 return false;
1249
1250 Type *CalleeParmTy = CalleeTy->getParamType(0);
1251 if (!CalleeParmTy->isPointerTy() ||
1252 (CalleeParmTy->getPointerAddressSpace() != 0))
1253 return false;
1254
1255 if (CI.getCallingConv() != F.getCallingConv())
1256 return false;
1257
1258 // CI should not has any ABI-impacting function attributes.
1259 static const Attribute::AttrKind ABIAttrs[] = {
1260 Attribute::StructRet, Attribute::ByVal, Attribute::InAlloca,
1261 Attribute::Preallocated, Attribute::InReg, Attribute::Returned,
1262 Attribute::SwiftSelf, Attribute::SwiftError};
1263 AttributeList Attrs = CI.getAttributes();
1264 for (auto AK : ABIAttrs)
1265 if (Attrs.hasParamAttribute(0, AK))
1266 return false;
1267
1268 return true;
1269}
1270
1271// Add musttail to any resume instructions that is immediately followed by a
1272// suspend (i.e. ret). We do this even in -O0 to support guaranteed tail call
1273// for symmetrical coroutine control transfer (C++ Coroutines TS extension).
1274// This transformation is done only in the resume part of the coroutine that has
1275// identical signature and calling convention as the coro.resume call.
1276static void addMustTailToCoroResumes(Function &F) {
1277 bool changed = false;
1278
1279 // Collect potential resume instructions.
1280 SmallVector<CallInst *, 4> Resumes;
1281 for (auto &I : instructions(F))
1282 if (auto *Call = dyn_cast<CallInst>(&I))
1283 if (shouldBeMustTail(*Call, F))
1284 Resumes.push_back(Call);
1285
1286 // Set musttail on those that are followed by a ret instruction.
1287 for (CallInst *Call : Resumes)
1288 if (simplifyTerminatorLeadingToRet(Call->getNextNode())) {
1289 Call->setTailCallKind(CallInst::TCK_MustTail);
1290 changed = true;
1291 }
1292
1293 if (changed)
1294 removeUnreachableBlocks(F);
1295}
1296
1297// Coroutine has no suspend points. Remove heap allocation for the coroutine
1298// frame if possible.
1299static void handleNoSuspendCoroutine(coro::Shape &Shape) {
1300 auto *CoroBegin = Shape.CoroBegin;
1301 auto *CoroId = CoroBegin->getId();
1302 auto *AllocInst = CoroId->getCoroAlloc();
1303 switch (Shape.ABI) {
1304 case coro::ABI::Switch: {
1305 auto SwitchId = cast<CoroIdInst>(CoroId);
1306 coro::replaceCoroFree(SwitchId, /*Elide=*/AllocInst != nullptr);
1307 if (AllocInst) {
1308 IRBuilder<> Builder(AllocInst);
1309 auto *Frame = Builder.CreateAlloca(Shape.FrameTy);
1310 Frame->setAlignment(Shape.FrameAlign);
1311 auto *VFrame = Builder.CreateBitCast(Frame, Builder.getInt8PtrTy());
1312 AllocInst->replaceAllUsesWith(Builder.getFalse());
1313 AllocInst->eraseFromParent();
1314 CoroBegin->replaceAllUsesWith(VFrame);
1315 } else {
1316 CoroBegin->replaceAllUsesWith(CoroBegin->getMem());
1317 }
1318
1319 break;
1320 }
1321 case coro::ABI::Async:
1322 case coro::ABI::Retcon:
1323 case coro::ABI::RetconOnce:
1324 CoroBegin->replaceAllUsesWith(UndefValue::get(CoroBegin->getType()));
1325 break;
1326 }
1327
1328 CoroBegin->eraseFromParent();
1329}
1330
1331// SimplifySuspendPoint needs to check that there is no calls between
1332// coro_save and coro_suspend, since any of the calls may potentially resume
1333// the coroutine and if that is the case we cannot eliminate the suspend point.
1334static bool hasCallsInBlockBetween(Instruction *From, Instruction *To) {
1335 for (Instruction *I = From; I != To; I = I->getNextNode()) {
1336 // Assume that no intrinsic can resume the coroutine.
1337 if (isa<IntrinsicInst>(I))
1338 continue;
1339
1340 if (isa<CallBase>(I))
1341 return true;
1342 }
1343 return false;
1344}
1345
1346static bool hasCallsInBlocksBetween(BasicBlock *SaveBB, BasicBlock *ResDesBB) {
1347 SmallPtrSet<BasicBlock *, 8> Set;
1348 SmallVector<BasicBlock *, 8> Worklist;
1349
1350 Set.insert(SaveBB);
1351 Worklist.push_back(ResDesBB);
1352
1353 // Accumulate all blocks between SaveBB and ResDesBB. Because CoroSaveIntr
1354 // returns a token consumed by suspend instruction, all blocks in between
1355 // will have to eventually hit SaveBB when going backwards from ResDesBB.
1356 while (!Worklist.empty()) {
1357 auto *BB = Worklist.pop_back_val();
1358 Set.insert(BB);
1359 for (auto *Pred : predecessors(BB))
1360 if (Set.count(Pred) == 0)
1361 Worklist.push_back(Pred);
1362 }
1363
1364 // SaveBB and ResDesBB are checked separately in hasCallsBetween.
1365 Set.erase(SaveBB);
1366 Set.erase(ResDesBB);
1367
1368 for (auto *BB : Set)
1369 if (hasCallsInBlockBetween(BB->getFirstNonPHI(), nullptr))
1370 return true;
1371
1372 return false;
1373}
1374
1375static bool hasCallsBetween(Instruction *Save, Instruction *ResumeOrDestroy) {
1376 auto *SaveBB = Save->getParent();
1377 auto *ResumeOrDestroyBB = ResumeOrDestroy->getParent();
1378
1379 if (SaveBB == ResumeOrDestroyBB)
1380 return hasCallsInBlockBetween(Save->getNextNode(), ResumeOrDestroy);
1381
1382 // Any calls from Save to the end of the block?
1383 if (hasCallsInBlockBetween(Save->getNextNode(), nullptr))
1384 return true;
1385
1386 // Any calls from begging of the block up to ResumeOrDestroy?
1387 if (hasCallsInBlockBetween(ResumeOrDestroyBB->getFirstNonPHI(),
1388 ResumeOrDestroy))
1389 return true;
1390
1391 // Any calls in all of the blocks between SaveBB and ResumeOrDestroyBB?
1392 if (hasCallsInBlocksBetween(SaveBB, ResumeOrDestroyBB))
1393 return true;
1394
1395 return false;
1396}
1397
1398// If a SuspendIntrin is preceded by Resume or Destroy, we can eliminate the
1399// suspend point and replace it with nornal control flow.
1400static bool simplifySuspendPoint(CoroSuspendInst *Suspend,
1401 CoroBeginInst *CoroBegin) {
1402 Instruction *Prev = Suspend->getPrevNode();
1403 if (!Prev) {
1404 auto *Pred = Suspend->getParent()->getSinglePredecessor();
1405 if (!Pred)
1406 return false;
1407 Prev = Pred->getTerminator();
1408 }
1409
1410 CallBase *CB = dyn_cast<CallBase>(Prev);
1411 if (!CB)
1412 return false;
1413
1414 auto *Callee = CB->getCalledOperand()->stripPointerCasts();
1415
1416 // See if the callsite is for resumption or destruction of the coroutine.
1417 auto *SubFn = dyn_cast<CoroSubFnInst>(Callee);
1418 if (!SubFn)
1419 return false;
1420
1421 // Does not refer to the current coroutine, we cannot do anything with it.
1422 if (SubFn->getFrame() != CoroBegin)
1423 return false;
1424
1425 // See if the transformation is safe. Specifically, see if there are any
1426 // calls in between Save and CallInstr. They can potenitally resume the
1427 // coroutine rendering this optimization unsafe.
1428 auto *Save = Suspend->getCoroSave();
1429 if (hasCallsBetween(Save, CB))
1430 return false;
1431
1432 // Replace llvm.coro.suspend with the value that results in resumption over
1433 // the resume or cleanup path.
1434 Suspend->replaceAllUsesWith(SubFn->getRawIndex());
1435 Suspend->eraseFromParent();
1436 Save->eraseFromParent();
1437
1438 // No longer need a call to coro.resume or coro.destroy.
1439 if (auto *Invoke = dyn_cast<InvokeInst>(CB)) {
1440 BranchInst::Create(Invoke->getNormalDest(), Invoke);
1441 }
1442
1443 // Grab the CalledValue from CB before erasing the CallInstr.
1444 auto *CalledValue = CB->getCalledOperand();
1445 CB->eraseFromParent();
1446
1447 // If no more users remove it. Usually it is a bitcast of SubFn.
1448 if (CalledValue != SubFn && CalledValue->user_empty())
1449 if (auto *I = dyn_cast<Instruction>(CalledValue))
1450 I->eraseFromParent();
1451
1452 // Now we are good to remove SubFn.
1453 if (SubFn->user_empty())
1454 SubFn->eraseFromParent();
1455
1456 return true;
1457}
1458
1459// Remove suspend points that are simplified.
1460static void simplifySuspendPoints(coro::Shape &Shape) {
1461 // Currently, the only simplification we do is switch-lowering-specific.
1462 if (Shape.ABI != coro::ABI::Switch)
1463 return;
1464
1465 auto &S = Shape.CoroSuspends;
1466 size_t I = 0, N = S.size();
1467 if (N == 0)
1468 return;
1469 while (true) {
1470 auto SI = cast<CoroSuspendInst>(S[I]);
1471 // Leave final.suspend to handleFinalSuspend since it is undefined behavior
1472 // to resume a coroutine suspended at the final suspend point.
1473 if (!SI->isFinal() && simplifySuspendPoint(SI, Shape.CoroBegin)) {
1474 if (--N == I)
1475 break;
1476 std::swap(S[I], S[N]);
1477 continue;
1478 }
1479 if (++I == N)
1480 break;
1481 }
1482 S.resize(N);
1483}
1484
1485static void splitSwitchCoroutine(Function &F, coro::Shape &Shape,
1486 SmallVectorImpl<Function *> &Clones) {
1487 assert(Shape.ABI == coro::ABI::Switch)((void)0);
1488
1489 createResumeEntryBlock(F, Shape);
1490 auto ResumeClone = createClone(F, ".resume", Shape,
12
Calling 'createClone'
1491 CoroCloner::Kind::SwitchResume);
1492 auto DestroyClone = createClone(F, ".destroy", Shape,
1493 CoroCloner::Kind::SwitchUnwind);
1494 auto CleanupClone = createClone(F, ".cleanup", Shape,
1495 CoroCloner::Kind::SwitchCleanup);
1496
1497 postSplitCleanup(*ResumeClone);
1498 postSplitCleanup(*DestroyClone);
1499 postSplitCleanup(*CleanupClone);
1500
1501 addMustTailToCoroResumes(*ResumeClone);
1502
1503 // Store addresses resume/destroy/cleanup functions in the coroutine frame.
1504 updateCoroFrame(Shape, ResumeClone, DestroyClone, CleanupClone);
1505
1506 assert(Clones.empty())((void)0);
1507 Clones.push_back(ResumeClone);
1508 Clones.push_back(DestroyClone);
1509 Clones.push_back(CleanupClone);
1510
1511 // Create a constant array referring to resume/destroy/clone functions pointed
1512 // by the last argument of @llvm.coro.info, so that CoroElide pass can
1513 // determined correct function to call.
1514 setCoroInfo(F, Shape, Clones);
1515}
1516
1517static void replaceAsyncResumeFunction(CoroSuspendAsyncInst *Suspend,
1518 Value *Continuation) {
1519 auto *ResumeIntrinsic = Suspend->getResumeFunction();
1520 auto &Context = Suspend->getParent()->getParent()->getContext();
1521 auto *Int8PtrTy = Type::getInt8PtrTy(Context);
1522
1523 IRBuilder<> Builder(ResumeIntrinsic);
1524 auto *Val = Builder.CreateBitOrPointerCast(Continuation, Int8PtrTy);
1525 ResumeIntrinsic->replaceAllUsesWith(Val);
1526 ResumeIntrinsic->eraseFromParent();
1527 Suspend->setOperand(CoroSuspendAsyncInst::ResumeFunctionArg,
1528 UndefValue::get(Int8PtrTy));
1529}
1530
1531/// Coerce the arguments in \p FnArgs according to \p FnTy in \p CallArgs.
1532static void coerceArguments(IRBuilder<> &Builder, FunctionType *FnTy,
1533 ArrayRef<Value *> FnArgs,
1534 SmallVectorImpl<Value *> &CallArgs) {
1535 size_t ArgIdx = 0;
1536 for (auto paramTy : FnTy->params()) {
1537 assert(ArgIdx < FnArgs.size())((void)0);
1538 if (paramTy != FnArgs[ArgIdx]->getType())
1539 CallArgs.push_back(
1540 Builder.CreateBitOrPointerCast(FnArgs[ArgIdx], paramTy));
1541 else
1542 CallArgs.push_back(FnArgs[ArgIdx]);
1543 ++ArgIdx;
1544 }
1545}
1546
1547CallInst *coro::createMustTailCall(DebugLoc Loc, Function *MustTailCallFn,
1548 ArrayRef<Value *> Arguments,
1549 IRBuilder<> &Builder) {
1550 auto *FnTy =
1551 cast<FunctionType>(MustTailCallFn->getType()->getPointerElementType());
1552 // Coerce the arguments, llvm optimizations seem to ignore the types in
1553 // vaarg functions and throws away casts in optimized mode.
1554 SmallVector<Value *, 8> CallArgs;
1555 coerceArguments(Builder, FnTy, Arguments, CallArgs);
1556
1557 auto *TailCall = Builder.CreateCall(FnTy, MustTailCallFn, CallArgs);
1558 TailCall->setTailCallKind(CallInst::TCK_MustTail);
1559 TailCall->setDebugLoc(Loc);
1560 TailCall->setCallingConv(MustTailCallFn->getCallingConv());
1561 return TailCall;
1562}
1563
1564static void splitAsyncCoroutine(Function &F, coro::Shape &Shape,
1565 SmallVectorImpl<Function *> &Clones) {
1566 assert(Shape.ABI == coro::ABI::Async)((void)0);
1567 assert(Clones.empty())((void)0);
1568 // Reset various things that the optimizer might have decided it
1569 // "knows" about the coroutine function due to not seeing a return.
1570 F.removeFnAttr(Attribute::NoReturn);
1571 F.removeAttribute(AttributeList::ReturnIndex, Attribute::NoAlias);
1572 F.removeAttribute(AttributeList::ReturnIndex, Attribute::NonNull);
1573
1574 auto &Context = F.getContext();
1575 auto *Int8PtrTy = Type::getInt8PtrTy(Context);
1576
1577 auto *Id = cast<CoroIdAsyncInst>(Shape.CoroBegin->getId());
1578 IRBuilder<> Builder(Id);
1579
1580 auto *FramePtr = Id->getStorage();
1581 FramePtr = Builder.CreateBitOrPointerCast(FramePtr, Int8PtrTy);
1582 FramePtr = Builder.CreateConstInBoundsGEP1_32(
1583 Type::getInt8Ty(Context), FramePtr, Shape.AsyncLowering.FrameOffset,
1584 "async.ctx.frameptr");
1585
1586 // Map all uses of llvm.coro.begin to the allocated frame pointer.
1587 {
1588 // Make sure we don't invalidate Shape.FramePtr.
1589 TrackingVH<Instruction> Handle(Shape.FramePtr);
1590 Shape.CoroBegin->replaceAllUsesWith(FramePtr);
1591 Shape.FramePtr = Handle.getValPtr();
1592 }
1593
1594 // Create all the functions in order after the main function.
1595 auto NextF = std::next(F.getIterator());
1596
1597 // Create a continuation function for each of the suspend points.
1598 Clones.reserve(Shape.CoroSuspends.size());
1599 for (size_t Idx = 0, End = Shape.CoroSuspends.size(); Idx != End; ++Idx) {
1600 auto *Suspend = cast<CoroSuspendAsyncInst>(Shape.CoroSuspends[Idx]);
1601
1602 // Create the clone declaration.
1603 auto ResumeNameSuffix = ".resume.";
1604 auto ProjectionFunctionName =
1605 Suspend->getAsyncContextProjectionFunction()->getName();
1606 bool UseSwiftMangling = false;
1607 if (ProjectionFunctionName.equals("__swift_async_resume_project_context")) {
1608 ResumeNameSuffix = "TQ";
1609 UseSwiftMangling = true;
1610 } else if (ProjectionFunctionName.equals(
1611 "__swift_async_resume_get_context")) {
1612 ResumeNameSuffix = "TY";
1613 UseSwiftMangling = true;
1614 }
1615 auto *Continuation = createCloneDeclaration(
1616 F, Shape,
1617 UseSwiftMangling ? ResumeNameSuffix + Twine(Idx) + "_"
1618 : ResumeNameSuffix + Twine(Idx),
1619 NextF, Suspend);
1620 Clones.push_back(Continuation);
1621
1622 // Insert a branch to a new return block immediately before the suspend
1623 // point.
1624 auto *SuspendBB = Suspend->getParent();
1625 auto *NewSuspendBB = SuspendBB->splitBasicBlock(Suspend);
1626 auto *Branch = cast<BranchInst>(SuspendBB->getTerminator());
1627
1628 // Place it before the first suspend.
1629 auto *ReturnBB =
1630 BasicBlock::Create(F.getContext(), "coro.return", &F, NewSuspendBB);
1631 Branch->setSuccessor(0, ReturnBB);
1632
1633 IRBuilder<> Builder(ReturnBB);
1634
1635 // Insert the call to the tail call function and inline it.
1636 auto *Fn = Suspend->getMustTailCallFunction();
1637 SmallVector<Value *, 8> Args(Suspend->args());
1638 auto FnArgs = ArrayRef<Value *>(Args).drop_front(
1639 CoroSuspendAsyncInst::MustTailCallFuncArg + 1);
1640 auto *TailCall =
1641 coro::createMustTailCall(Suspend->getDebugLoc(), Fn, FnArgs, Builder);
1642 Builder.CreateRetVoid();
1643 InlineFunctionInfo FnInfo;
1644 auto InlineRes = InlineFunction(*TailCall, FnInfo);
1645 assert(InlineRes.isSuccess() && "Expected inlining to succeed")((void)0);
1646 (void)InlineRes;
1647
1648 // Replace the lvm.coro.async.resume intrisic call.
1649 replaceAsyncResumeFunction(Suspend, Continuation);
1650 }
1651
1652 assert(Clones.size() == Shape.CoroSuspends.size())((void)0);
1653 for (size_t Idx = 0, End = Shape.CoroSuspends.size(); Idx != End; ++Idx) {
1654 auto *Suspend = Shape.CoroSuspends[Idx];
1655 auto *Clone = Clones[Idx];
1656
1657 CoroCloner(F, "resume." + Twine(Idx), Shape, Clone, Suspend).create();
1658 }
1659}
1660
1661static void splitRetconCoroutine(Function &F, coro::Shape &Shape,
1662 SmallVectorImpl<Function *> &Clones) {
1663 assert(Shape.ABI == coro::ABI::Retcon ||((void)0)
1664 Shape.ABI == coro::ABI::RetconOnce)((void)0);
1665 assert(Clones.empty())((void)0);
1666
1667 // Reset various things that the optimizer might have decided it
1668 // "knows" about the coroutine function due to not seeing a return.
1669 F.removeFnAttr(Attribute::NoReturn);
1670 F.removeAttribute(AttributeList::ReturnIndex, Attribute::NoAlias);
1671 F.removeAttribute(AttributeList::ReturnIndex, Attribute::NonNull);
1672
1673 // Allocate the frame.
1674 auto *Id = cast<AnyCoroIdRetconInst>(Shape.CoroBegin->getId());
1675 Value *RawFramePtr;
1676 if (Shape.RetconLowering.IsFrameInlineInStorage) {
1677 RawFramePtr = Id->getStorage();
1678 } else {
1679 IRBuilder<> Builder(Id);
1680
1681 // Determine the size of the frame.
1682 const DataLayout &DL = F.getParent()->getDataLayout();
1683 auto Size = DL.getTypeAllocSize(Shape.FrameTy);
1684
1685 // Allocate. We don't need to update the call graph node because we're
1686 // going to recompute it from scratch after splitting.
1687 // FIXME: pass the required alignment
1688 RawFramePtr = Shape.emitAlloc(Builder, Builder.getInt64(Size), nullptr);
1689 RawFramePtr =
1690 Builder.CreateBitCast(RawFramePtr, Shape.CoroBegin->getType());
1691
1692 // Stash the allocated frame pointer in the continuation storage.
1693 auto Dest = Builder.CreateBitCast(Id->getStorage(),
1694 RawFramePtr->getType()->getPointerTo());
1695 Builder.CreateStore(RawFramePtr, Dest);
1696 }
1697
1698 // Map all uses of llvm.coro.begin to the allocated frame pointer.
1699 {
1700 // Make sure we don't invalidate Shape.FramePtr.
1701 TrackingVH<Instruction> Handle(Shape.FramePtr);
1702 Shape.CoroBegin->replaceAllUsesWith(RawFramePtr);
1703 Shape.FramePtr = Handle.getValPtr();
1704 }
1705
1706 // Create a unique return block.
1707 BasicBlock *ReturnBB = nullptr;
1708 SmallVector<PHINode *, 4> ReturnPHIs;
1709
1710 // Create all the functions in order after the main function.
1711 auto NextF = std::next(F.getIterator());
1712
1713 // Create a continuation function for each of the suspend points.
1714 Clones.reserve(Shape.CoroSuspends.size());
1715 for (size_t i = 0, e = Shape.CoroSuspends.size(); i != e; ++i) {
1716 auto Suspend = cast<CoroSuspendRetconInst>(Shape.CoroSuspends[i]);
1717
1718 // Create the clone declaration.
1719 auto Continuation =
1720 createCloneDeclaration(F, Shape, ".resume." + Twine(i), NextF, nullptr);
1721 Clones.push_back(Continuation);
1722
1723 // Insert a branch to the unified return block immediately before
1724 // the suspend point.
1725 auto SuspendBB = Suspend->getParent();
1726 auto NewSuspendBB = SuspendBB->splitBasicBlock(Suspend);
1727 auto Branch = cast<BranchInst>(SuspendBB->getTerminator());
1728
1729 // Create the unified return block.
1730 if (!ReturnBB) {
1731 // Place it before the first suspend.
1732 ReturnBB = BasicBlock::Create(F.getContext(), "coro.return", &F,
1733 NewSuspendBB);
1734 Shape.RetconLowering.ReturnBlock = ReturnBB;
1735
1736 IRBuilder<> Builder(ReturnBB);
1737
1738 // Create PHIs for all the return values.
1739 assert(ReturnPHIs.empty())((void)0);
1740
1741 // First, the continuation.
1742 ReturnPHIs.push_back(Builder.CreatePHI(Continuation->getType(),
1743 Shape.CoroSuspends.size()));
1744
1745 // Next, all the directly-yielded values.
1746 for (auto ResultTy : Shape.getRetconResultTypes())
1747 ReturnPHIs.push_back(Builder.CreatePHI(ResultTy,
1748 Shape.CoroSuspends.size()));
1749
1750 // Build the return value.
1751 auto RetTy = F.getReturnType();
1752
1753 // Cast the continuation value if necessary.
1754 // We can't rely on the types matching up because that type would
1755 // have to be infinite.
1756 auto CastedContinuationTy =
1757 (ReturnPHIs.size() == 1 ? RetTy : RetTy->getStructElementType(0));
1758 auto *CastedContinuation =
1759 Builder.CreateBitCast(ReturnPHIs[0], CastedContinuationTy);
1760
1761 Value *RetV;
1762 if (ReturnPHIs.size() == 1) {
1763 RetV = CastedContinuation;
1764 } else {
1765 RetV = UndefValue::get(RetTy);
1766 RetV = Builder.CreateInsertValue(RetV, CastedContinuation, 0);
1767 for (size_t I = 1, E = ReturnPHIs.size(); I != E; ++I)
1768 RetV = Builder.CreateInsertValue(RetV, ReturnPHIs[I], I);
1769 }
1770
1771 Builder.CreateRet(RetV);
1772 }
1773
1774 // Branch to the return block.
1775 Branch->setSuccessor(0, ReturnBB);
1776 ReturnPHIs[0]->addIncoming(Continuation, SuspendBB);
1777 size_t NextPHIIndex = 1;
1778 for (auto &VUse : Suspend->value_operands())
1779 ReturnPHIs[NextPHIIndex++]->addIncoming(&*VUse, SuspendBB);
1780 assert(NextPHIIndex == ReturnPHIs.size())((void)0);
1781 }
1782
1783 assert(Clones.size() == Shape.CoroSuspends.size())((void)0);
1784 for (size_t i = 0, e = Shape.CoroSuspends.size(); i != e; ++i) {
1785 auto Suspend = Shape.CoroSuspends[i];
1786 auto Clone = Clones[i];
1787
1788 CoroCloner(F, "resume." + Twine(i), Shape, Clone, Suspend).create();
1789 }
1790}
1791
1792namespace {
1793 class PrettyStackTraceFunction : public PrettyStackTraceEntry {
1794 Function &F;
1795 public:
1796 PrettyStackTraceFunction(Function &F) : F(F) {}
1797 void print(raw_ostream &OS) const override {
1798 OS << "While splitting coroutine ";
1799 F.printAsOperand(OS, /*print type*/ false, F.getParent());
1800 OS << "\n";
1801 }
1802 };
1803}
1804
1805static coro::Shape splitCoroutine(Function &F,
1806 SmallVectorImpl<Function *> &Clones,
1807 bool ReuseFrameSlot) {
1808 PrettyStackTraceFunction prettyStackTrace(F);
1809
1810 // The suspend-crossing algorithm in buildCoroutineFrame get tripped
1811 // up by uses in unreachable blocks, so remove them as a first pass.
1812 removeUnreachableBlocks(F);
1813
1814 coro::Shape Shape(F, ReuseFrameSlot);
1815 if (!Shape.CoroBegin)
7
Assuming field 'CoroBegin' is non-null
8
Taking false branch
1816 return Shape;
1817
1818 simplifySuspendPoints(Shape);
1819 buildCoroutineFrame(F, Shape);
1820 replaceFrameSize(Shape);
1821
1822 // If there are no suspend points, no split required, just remove
1823 // the allocation and deallocation blocks, they are not needed.
1824 if (Shape.CoroSuspends.empty()) {
9
Taking false branch
1825 handleNoSuspendCoroutine(Shape);
1826 } else {
1827 switch (Shape.ABI) {
10
Control jumps to 'case Switch:' at line 1828
1828 case coro::ABI::Switch:
1829 splitSwitchCoroutine(F, Shape, Clones);
11
Calling 'splitSwitchCoroutine'
1830 break;
1831 case coro::ABI::Async:
1832 splitAsyncCoroutine(F, Shape, Clones);
1833 break;
1834 case coro::ABI::Retcon:
1835 case coro::ABI::RetconOnce:
1836 splitRetconCoroutine(F, Shape, Clones);
1837 break;
1838 }
1839 }
1840
1841 // Replace all the swifterror operations in the original function.
1842 // This invalidates SwiftErrorOps in the Shape.
1843 replaceSwiftErrorOps(F, Shape, nullptr);
1844
1845 return Shape;
1846}
1847
1848static void
1849updateCallGraphAfterCoroutineSplit(Function &F, const coro::Shape &Shape,
1850 const SmallVectorImpl<Function *> &Clones,
1851 CallGraph &CG, CallGraphSCC &SCC) {
1852 if (!Shape.CoroBegin)
1853 return;
1854
1855 removeCoroEnds(Shape, &CG);
1856 postSplitCleanup(F);
1857
1858 // Update call graph and add the functions we created to the SCC.
1859 coro::updateCallGraph(F, Clones, CG, SCC);
1860}
1861
1862static void updateCallGraphAfterCoroutineSplit(
1863 LazyCallGraph::Node &N, const coro::Shape &Shape,
1864 const SmallVectorImpl<Function *> &Clones, LazyCallGraph::SCC &C,
1865 LazyCallGraph &CG, CGSCCAnalysisManager &AM, CGSCCUpdateResult &UR,
1866 FunctionAnalysisManager &FAM) {
1867 if (!Shape.CoroBegin)
1868 return;
1869
1870 for (llvm::AnyCoroEndInst *End : Shape.CoroEnds) {
1871 auto &Context = End->getContext();
1872 End->replaceAllUsesWith(ConstantInt::getFalse(Context));
1873 End->eraseFromParent();
1874 }
1875
1876 if (!Clones.empty()) {
1877 switch (Shape.ABI) {
1878 case coro::ABI::Switch:
1879 // Each clone in the Switch lowering is independent of the other clones.
1880 // Let the LazyCallGraph know about each one separately.
1881 for (Function *Clone : Clones)
1882 CG.addSplitFunction(N.getFunction(), *Clone);
1883 break;
1884 case coro::ABI::Async:
1885 case coro::ABI::Retcon:
1886 case coro::ABI::RetconOnce:
1887 // Each clone in the Async/Retcon lowering references of the other clones.
1888 // Let the LazyCallGraph know about all of them at once.
1889 if (!Clones.empty())
1890 CG.addSplitRefRecursiveFunctions(N.getFunction(), Clones);
1891 break;
1892 }
1893
1894 // Let the CGSCC infra handle the changes to the original function.
1895 updateCGAndAnalysisManagerForCGSCCPass(CG, C, N, AM, UR, FAM);
1896 }
1897
1898 // Do some cleanup and let the CGSCC infra see if we've cleaned up any edges
1899 // to the split functions.
1900 postSplitCleanup(N.getFunction());
1901 updateCGAndAnalysisManagerForFunctionPass(CG, C, N, AM, UR, FAM);
1902}
1903
1904// When we see the coroutine the first time, we insert an indirect call to a
1905// devirt trigger function and mark the coroutine that it is now ready for
1906// split.
1907// Async lowering uses this after it has split the function to restart the
1908// pipeline.
1909static void prepareForSplit(Function &F, CallGraph &CG,
1910 bool MarkForAsyncRestart = false) {
1911 Module &M = *F.getParent();
1912 LLVMContext &Context = F.getContext();
1913#ifndef NDEBUG1
1914 Function *DevirtFn = M.getFunction(CORO_DEVIRT_TRIGGER_FN"coro.devirt.trigger");
1915 assert(DevirtFn && "coro.devirt.trigger function not found")((void)0);
1916#endif
1917
1918 F.addFnAttr(CORO_PRESPLIT_ATTR"coroutine.presplit", MarkForAsyncRestart
1919 ? ASYNC_RESTART_AFTER_SPLIT"2"
1920 : PREPARED_FOR_SPLIT"1");
1921
1922 // Insert an indirect call sequence that will be devirtualized by CoroElide
1923 // pass:
1924 // %0 = call i8* @llvm.coro.subfn.addr(i8* null, i8 -1)
1925 // %1 = bitcast i8* %0 to void(i8*)*
1926 // call void %1(i8* null)
1927 coro::LowererBase Lowerer(M);
1928 Instruction *InsertPt =
1929 MarkForAsyncRestart ? F.getEntryBlock().getFirstNonPHIOrDbgOrLifetime()
1930 : F.getEntryBlock().getTerminator();
1931 auto *Null = ConstantPointerNull::get(Type::getInt8PtrTy(Context));
1932 auto *DevirtFnAddr =
1933 Lowerer.makeSubFnCall(Null, CoroSubFnInst::RestartTrigger, InsertPt);
1934 FunctionType *FnTy = FunctionType::get(Type::getVoidTy(Context),
1935 {Type::getInt8PtrTy(Context)}, false);
1936 auto *IndirectCall = CallInst::Create(FnTy, DevirtFnAddr, Null, "", InsertPt);
1937
1938 // Update CG graph with an indirect call we just added.
1939 CG[&F]->addCalledFunction(IndirectCall, CG.getCallsExternalNode());
1940}
1941
1942// Make sure that there is a devirtualization trigger function that the
1943// coro-split pass uses to force a restart of the CGSCC pipeline. If the devirt
1944// trigger function is not found, we will create one and add it to the current
1945// SCC.
1946static void createDevirtTriggerFunc(CallGraph &CG, CallGraphSCC &SCC) {
1947 Module &M = CG.getModule();
1948 if (M.getFunction(CORO_DEVIRT_TRIGGER_FN"coro.devirt.trigger"))
1949 return;
1950
1951 LLVMContext &C = M.getContext();
1952 auto *FnTy = FunctionType::get(Type::getVoidTy(C), Type::getInt8PtrTy(C),
1953 /*isVarArg=*/false);
1954 Function *DevirtFn =
1955 Function::Create(FnTy, GlobalValue::LinkageTypes::PrivateLinkage,
1956 CORO_DEVIRT_TRIGGER_FN"coro.devirt.trigger", &M);
1957 DevirtFn->addFnAttr(Attribute::AlwaysInline);
1958 auto *Entry = BasicBlock::Create(C, "entry", DevirtFn);
1959 ReturnInst::Create(C, Entry);
1960
1961 auto *Node = CG.getOrInsertFunction(DevirtFn);
1962
1963 SmallVector<CallGraphNode *, 8> Nodes(SCC.begin(), SCC.end());
1964 Nodes.push_back(Node);
1965 SCC.initialize(Nodes);
1966}
1967
1968/// Replace a call to llvm.coro.prepare.retcon.
1969static void replacePrepare(CallInst *Prepare, LazyCallGraph &CG,
1970 LazyCallGraph::SCC &C) {
1971 auto CastFn = Prepare->getArgOperand(0); // as an i8*
1972 auto Fn = CastFn->stripPointerCasts(); // as its original type
1973
1974 // Attempt to peephole this pattern:
1975 // %0 = bitcast [[TYPE]] @some_function to i8*
1976 // %1 = call @llvm.coro.prepare.retcon(i8* %0)
1977 // %2 = bitcast %1 to [[TYPE]]
1978 // ==>
1979 // %2 = @some_function
1980 for (auto UI = Prepare->use_begin(), UE = Prepare->use_end(); UI != UE;) {
1981 // Look for bitcasts back to the original function type.
1982 auto *Cast = dyn_cast<BitCastInst>((UI++)->getUser());
1983 if (!Cast || Cast->getType() != Fn->getType())
1984 continue;
1985
1986 // Replace and remove the cast.
1987 Cast->replaceAllUsesWith(Fn);
1988 Cast->eraseFromParent();
1989 }
1990
1991 // Replace any remaining uses with the function as an i8*.
1992 // This can never directly be a callee, so we don't need to update CG.
1993 Prepare->replaceAllUsesWith(CastFn);
1994 Prepare->eraseFromParent();
1995
1996 // Kill dead bitcasts.
1997 while (auto *Cast = dyn_cast<BitCastInst>(CastFn)) {
1998 if (!Cast->use_empty())
1999 break;
2000 CastFn = Cast->getOperand(0);
2001 Cast->eraseFromParent();
2002 }
2003}
2004/// Replace a call to llvm.coro.prepare.retcon.
2005static void replacePrepare(CallInst *Prepare, CallGraph &CG) {
2006 auto CastFn = Prepare->getArgOperand(0); // as an i8*
2007 auto Fn = CastFn->stripPointerCasts(); // as its original type
2008
2009 // Find call graph nodes for the preparation.
2010 CallGraphNode *PrepareUserNode = nullptr, *FnNode = nullptr;
2011 if (auto ConcreteFn = dyn_cast<Function>(Fn)) {
2012 PrepareUserNode = CG[Prepare->getFunction()];
2013 FnNode = CG[ConcreteFn];
2014 }
2015
2016 // Attempt to peephole this pattern:
2017 // %0 = bitcast [[TYPE]] @some_function to i8*
2018 // %1 = call @llvm.coro.prepare.retcon(i8* %0)
2019 // %2 = bitcast %1 to [[TYPE]]
2020 // ==>
2021 // %2 = @some_function
2022 for (auto UI = Prepare->use_begin(), UE = Prepare->use_end();
2023 UI != UE; ) {
2024 // Look for bitcasts back to the original function type.
2025 auto *Cast = dyn_cast<BitCastInst>((UI++)->getUser());
2026 if (!Cast || Cast->getType() != Fn->getType()) continue;
2027
2028 // Check whether the replacement will introduce new direct calls.
2029 // If so, we'll need to update the call graph.
2030 if (PrepareUserNode) {
2031 for (auto &Use : Cast->uses()) {
2032 if (auto *CB = dyn_cast<CallBase>(Use.getUser())) {
2033 if (!CB->isCallee(&Use))
2034 continue;
2035 PrepareUserNode->removeCallEdgeFor(*CB);
2036 PrepareUserNode->addCalledFunction(CB, FnNode);
2037 }
2038 }
2039 }
2040
2041 // Replace and remove the cast.
2042 Cast->replaceAllUsesWith(Fn);
2043 Cast->eraseFromParent();
2044 }
2045
2046 // Replace any remaining uses with the function as an i8*.
2047 // This can never directly be a callee, so we don't need to update CG.
2048 Prepare->replaceAllUsesWith(CastFn);
2049 Prepare->eraseFromParent();
2050
2051 // Kill dead bitcasts.
2052 while (auto *Cast = dyn_cast<BitCastInst>(CastFn)) {
2053 if (!Cast->use_empty()) break;
2054 CastFn = Cast->getOperand(0);
2055 Cast->eraseFromParent();
2056 }
2057}
2058
2059static bool replaceAllPrepares(Function *PrepareFn, LazyCallGraph &CG,
2060 LazyCallGraph::SCC &C) {
2061 bool Changed = false;
2062 for (auto PI = PrepareFn->use_begin(), PE = PrepareFn->use_end(); PI != PE;) {
2063 // Intrinsics can only be used in calls.
2064 auto *Prepare = cast<CallInst>((PI++)->getUser());
2065 replacePrepare(Prepare, CG, C);
2066 Changed = true;
2067 }
2068
2069 return Changed;
2070}
2071
2072/// Remove calls to llvm.coro.prepare.retcon, a barrier meant to prevent
2073/// IPO from operating on calls to a retcon coroutine before it's been
2074/// split. This is only safe to do after we've split all retcon
2075/// coroutines in the module. We can do that this in this pass because
2076/// this pass does promise to split all retcon coroutines (as opposed to
2077/// switch coroutines, which are lowered in multiple stages).
2078static bool replaceAllPrepares(Function *PrepareFn, CallGraph &CG) {
2079 bool Changed = false;
2080 for (auto PI = PrepareFn->use_begin(), PE = PrepareFn->use_end();
2081 PI != PE; ) {
2082 // Intrinsics can only be used in calls.
2083 auto *Prepare = cast<CallInst>((PI++)->getUser());
2084 replacePrepare(Prepare, CG);
2085 Changed = true;
2086 }
2087
2088 return Changed;
2089}
2090
2091static bool declaresCoroSplitIntrinsics(const Module &M) {
2092 return coro::declaresIntrinsics(M, {"llvm.coro.begin",
2093 "llvm.coro.prepare.retcon",
2094 "llvm.coro.prepare.async"});
2095}
2096
2097static void addPrepareFunction(const Module &M,
2098 SmallVectorImpl<Function *> &Fns,
2099 StringRef Name) {
2100 auto *PrepareFn = M.getFunction(Name);
2101 if (PrepareFn && !PrepareFn->use_empty())
2102 Fns.push_back(PrepareFn);
2103}
2104
2105PreservedAnalyses CoroSplitPass::run(LazyCallGraph::SCC &C,
2106 CGSCCAnalysisManager &AM,
2107 LazyCallGraph &CG, CGSCCUpdateResult &UR) {
2108 // NB: One invariant of a valid LazyCallGraph::SCC is that it must contain a
2109 // non-zero number of nodes, so we assume that here and grab the first
2110 // node's function's module.
2111 Module &M = *C.begin()->getFunction().getParent();
2112 auto &FAM =
2113 AM.getResult<FunctionAnalysisManagerCGSCCProxy>(C, CG).getManager();
2114
2115 if (!declaresCoroSplitIntrinsics(M))
1
Assuming the condition is false
2
Taking false branch
2116 return PreservedAnalyses::all();
2117
2118 // Check for uses of llvm.coro.prepare.retcon/async.
2119 SmallVector<Function *, 2> PrepareFns;
2120 addPrepareFunction(M, PrepareFns, "llvm.coro.prepare.retcon");
2121 addPrepareFunction(M, PrepareFns, "llvm.coro.prepare.async");
2122
2123 // Find coroutines for processing.
2124 SmallVector<LazyCallGraph::Node *, 4> Coroutines;
2125 for (LazyCallGraph::Node &N : C)
2126 if (N.getFunction().hasFnAttribute(CORO_PRESPLIT_ATTR"coroutine.presplit"))
2127 Coroutines.push_back(&N);
2128
2129 if (Coroutines.empty() && PrepareFns.empty())
2130 return PreservedAnalyses::all();
2131
2132 if (Coroutines.empty()) {
3
Taking false branch
2133 for (auto *PrepareFn : PrepareFns) {
2134 replaceAllPrepares(PrepareFn, CG, C);
2135 }
2136 }
2137
2138 // Split all the coroutines.
2139 for (LazyCallGraph::Node *N : Coroutines) {
4
Assuming '__begin1' is not equal to '__end1'
2140 Function &F = N->getFunction();
2141 LLVM_DEBUG(dbgs() << "CoroSplit: Processing coroutine '" << F.getName()do { } while (false)
5
Loop condition is false. Exiting loop
2142 << "' state: "do { } while (false)
2143 << F.getFnAttribute(CORO_PRESPLIT_ATTR).getValueAsString()do { } while (false)
2144 << "\n")do { } while (false);
2145 F.removeFnAttr(CORO_PRESPLIT_ATTR"coroutine.presplit");
2146
2147 SmallVector<Function *, 4> Clones;
2148 const coro::Shape Shape = splitCoroutine(F, Clones, ReuseFrameSlot);
6
Calling 'splitCoroutine'
2149 updateCallGraphAfterCoroutineSplit(*N, Shape, Clones, C, CG, AM, UR, FAM);
2150
2151 if (!Shape.CoroSuspends.empty()) {
2152 // Run the CGSCC pipeline on the original and newly split functions.
2153 UR.CWorklist.insert(&C);
2154 for (Function *Clone : Clones)
2155 UR.CWorklist.insert(CG.lookupSCC(CG.get(*Clone)));
2156 }
2157 }
2158
2159 if (!PrepareFns.empty()) {
2160 for (auto *PrepareFn : PrepareFns) {
2161 replaceAllPrepares(PrepareFn, CG, C);
2162 }
2163 }
2164
2165 return PreservedAnalyses::none();
2166}
2167
2168namespace {
2169
2170// We present a coroutine to LLVM as an ordinary function with suspension
2171// points marked up with intrinsics. We let the optimizer party on the coroutine
2172// as a single function for as long as possible. Shortly before the coroutine is
2173// eligible to be inlined into its callers, we split up the coroutine into parts
2174// corresponding to initial, resume and destroy invocations of the coroutine,
2175// add them to the current SCC and restart the IPO pipeline to optimize the
2176// coroutine subfunctions we extracted before proceeding to the caller of the
2177// coroutine.
2178struct CoroSplitLegacy : public CallGraphSCCPass {
2179 static char ID; // Pass identification, replacement for typeid
2180
2181 CoroSplitLegacy(bool ReuseFrameSlot = false)
2182 : CallGraphSCCPass(ID), ReuseFrameSlot(ReuseFrameSlot) {
2183 initializeCoroSplitLegacyPass(*PassRegistry::getPassRegistry());
2184 }
2185
2186 bool Run = false;
2187 bool ReuseFrameSlot;
2188
2189 // A coroutine is identified by the presence of coro.begin intrinsic, if
2190 // we don't have any, this pass has nothing to do.
2191 bool doInitialization(CallGraph &CG) override {
2192 Run = declaresCoroSplitIntrinsics(CG.getModule());
2193 return CallGraphSCCPass::doInitialization(CG);
2194 }
2195
2196 bool runOnSCC(CallGraphSCC &SCC) override {
2197 if (!Run)
2198 return false;
2199
2200 // Check for uses of llvm.coro.prepare.retcon.
2201 SmallVector<Function *, 2> PrepareFns;
2202 auto &M = SCC.getCallGraph().getModule();
2203 addPrepareFunction(M, PrepareFns, "llvm.coro.prepare.retcon");
2204 addPrepareFunction(M, PrepareFns, "llvm.coro.prepare.async");
2205
2206 // Find coroutines for processing.
2207 SmallVector<Function *, 4> Coroutines;
2208 for (CallGraphNode *CGN : SCC)
2209 if (auto *F = CGN->getFunction())
2210 if (F->hasFnAttribute(CORO_PRESPLIT_ATTR"coroutine.presplit"))
2211 Coroutines.push_back(F);
2212
2213 if (Coroutines.empty() && PrepareFns.empty())
2214 return false;
2215
2216 CallGraph &CG = getAnalysis<CallGraphWrapperPass>().getCallGraph();
2217
2218 if (Coroutines.empty()) {
2219 bool Changed = false;
2220 for (auto *PrepareFn : PrepareFns)
2221 Changed |= replaceAllPrepares(PrepareFn, CG);
2222 return Changed;
2223 }
2224
2225 createDevirtTriggerFunc(CG, SCC);
2226
2227 // Split all the coroutines.
2228 for (Function *F : Coroutines) {
2229 Attribute Attr = F->getFnAttribute(CORO_PRESPLIT_ATTR"coroutine.presplit");
2230 StringRef Value = Attr.getValueAsString();
2231 LLVM_DEBUG(dbgs() << "CoroSplit: Processing coroutine '" << F->getName()do { } while (false)
2232 << "' state: " << Value << "\n")do { } while (false);
2233 // Async lowering marks coroutines to trigger a restart of the pipeline
2234 // after it has split them.
2235 if (Value == ASYNC_RESTART_AFTER_SPLIT"2") {
2236 F->removeFnAttr(CORO_PRESPLIT_ATTR"coroutine.presplit");
2237 continue;
2238 }
2239 if (Value == UNPREPARED_FOR_SPLIT"0") {
2240 prepareForSplit(*F, CG);
2241 continue;
2242 }
2243 F->removeFnAttr(CORO_PRESPLIT_ATTR"coroutine.presplit");
2244
2245 SmallVector<Function *, 4> Clones;
2246 const coro::Shape Shape = splitCoroutine(*F, Clones, ReuseFrameSlot);
2247 updateCallGraphAfterCoroutineSplit(*F, Shape, Clones, CG, SCC);
2248 if (Shape.ABI == coro::ABI::Async) {
2249 // Restart SCC passes.
2250 // Mark function for CoroElide pass. It will devirtualize causing a
2251 // restart of the SCC pipeline.
2252 prepareForSplit(*F, CG, true /*MarkForAsyncRestart*/);
2253 }
2254 }
2255
2256 for (auto *PrepareFn : PrepareFns)
2257 replaceAllPrepares(PrepareFn, CG);
2258
2259 return true;
2260 }
2261
2262 void getAnalysisUsage(AnalysisUsage &AU) const override {
2263 CallGraphSCCPass::getAnalysisUsage(AU);
2264 }
2265
2266 StringRef getPassName() const override { return "Coroutine Splitting"; }
2267};
2268
2269} // end anonymous namespace
2270
2271char CoroSplitLegacy::ID = 0;
2272
2273INITIALIZE_PASS_BEGIN(static void *initializeCoroSplitLegacyPassOnce(PassRegistry &
Registry) {
2274 CoroSplitLegacy, "coro-split",static void *initializeCoroSplitLegacyPassOnce(PassRegistry &
Registry) {
2275 "Split coroutine into a set of functions driving its state machine", false,static void *initializeCoroSplitLegacyPassOnce(PassRegistry &
Registry) {
2276 false)static void *initializeCoroSplitLegacyPassOnce(PassRegistry &
Registry) {
2277INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)initializeCallGraphWrapperPassPass(Registry);
2278INITIALIZE_PASS_END(PassInfo *PI = new PassInfo( "Split coroutine into a set of functions driving its state machine"
, "coro-split", &CoroSplitLegacy::ID, PassInfo::NormalCtor_t
(callDefaultCtor<CoroSplitLegacy>), false, false); Registry
.registerPass(*PI, true); return PI; } static llvm::once_flag
InitializeCoroSplitLegacyPassFlag; void llvm::initializeCoroSplitLegacyPass
(PassRegistry &Registry) { llvm::call_once(InitializeCoroSplitLegacyPassFlag
, initializeCoroSplitLegacyPassOnce, std::ref(Registry)); }
2279 CoroSplitLegacy, "coro-split",PassInfo *PI = new PassInfo( "Split coroutine into a set of functions driving its state machine"
, "coro-split", &CoroSplitLegacy::ID, PassInfo::NormalCtor_t
(callDefaultCtor<CoroSplitLegacy>), false, false); Registry
.registerPass(*PI, true); return PI; } static llvm::once_flag
InitializeCoroSplitLegacyPassFlag; void llvm::initializeCoroSplitLegacyPass
(PassRegistry &Registry) { llvm::call_once(InitializeCoroSplitLegacyPassFlag
, initializeCoroSplitLegacyPassOnce, std::ref(Registry)); }
2280 "Split coroutine into a set of functions driving its state machine", false,PassInfo *PI = new PassInfo( "Split coroutine into a set of functions driving its state machine"
, "coro-split", &CoroSplitLegacy::ID, PassInfo::NormalCtor_t
(callDefaultCtor<CoroSplitLegacy>), false, false); Registry
.registerPass(*PI, true); return PI; } static llvm::once_flag
InitializeCoroSplitLegacyPassFlag; void llvm::initializeCoroSplitLegacyPass
(PassRegistry &Registry) { llvm::call_once(InitializeCoroSplitLegacyPassFlag
, initializeCoroSplitLegacyPassOnce, std::ref(Registry)); }
2281 false)PassInfo *PI = new PassInfo( "Split coroutine into a set of functions driving its state machine"
, "coro-split", &CoroSplitLegacy::ID, PassInfo::NormalCtor_t
(callDefaultCtor<CoroSplitLegacy>), false, false); Registry
.registerPass(*PI, true); return PI; } static llvm::once_flag
InitializeCoroSplitLegacyPassFlag; void llvm::initializeCoroSplitLegacyPass
(PassRegistry &Registry) { llvm::call_once(InitializeCoroSplitLegacyPassFlag
, initializeCoroSplitLegacyPassOnce, std::ref(Registry)); }
2282
2283Pass *llvm::createCoroSplitLegacyPass(bool ReuseFrameSlot) {
2284 return new CoroSplitLegacy(ReuseFrameSlot);
2285}