Bug Summary

File:src/lib/libm/src/k_rem_pio2f.c
Warning:line 188, column 27
Assigned value is garbage or undefined

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 k_rem_pio2f.c -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -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 pic -pic-level 1 -fhalf-no-semantic-interposition -mframe-pointer=all -relaxed-aliasing -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -target-feature +retpoline-indirect-calls -target-feature +retpoline-indirect-branches -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/lib/libm/obj -resource-dir /usr/local/lib/clang/13.0.0 -include namespace.h -I /usr/src/lib/libm/arch/amd64 -I /usr/src/lib/libm/src -I /usr/src/lib/libm/src/ld80 -I /usr/src/lib/libm/hidden -D PIC -internal-isystem /usr/local/lib/clang/13.0.0/include -internal-externc-isystem /usr/include -O2 -fdebug-compilation-dir=/usr/src/lib/libm/obj -ferror-limit 19 -fwrapv -D_RET_PROTECTOR -ret-protector -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/lib/libm/src/k_rem_pio2f.c
1/* k_rem_pio2f.c -- float version of k_rem_pio2.c
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3 */
4
5/*
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
8 *
9 * Developed at SunPro, a Sun Microsystems, Inc. business.
10 * Permission to use, copy, modify, and distribute this
11 * software is freely granted, provided that this notice
12 * is preserved.
13 * ====================================================
14 */
15
16#include "math.h"
17#include "math_private.h"
18
19/* In the float version, the input parameter x contains 8 bit
20 integers, not 24 bit integers. 113 bit precision is not supported. */
21
22static const int init_jk[] = {4,7,9}; /* initial value for jk */
23
24static const float PIo2[] = {
25 1.5703125000e+00, /* 0x3fc90000 */
26 4.5776367188e-04, /* 0x39f00000 */
27 2.5987625122e-05, /* 0x37da0000 */
28 7.5437128544e-08, /* 0x33a20000 */
29 6.0026650317e-11, /* 0x2e840000 */
30 7.3896444519e-13, /* 0x2b500000 */
31 5.3845816694e-15, /* 0x27c20000 */
32 5.6378512969e-18, /* 0x22d00000 */
33 8.3009228831e-20, /* 0x1fc40000 */
34 3.2756352257e-22, /* 0x1bc60000 */
35 6.3331015649e-25, /* 0x17440000 */
36};
37
38static const float
39zero = 0.0,
40one = 1.0,
41two8 = 2.5600000000e+02, /* 0x43800000 */
42twon8 = 3.9062500000e-03; /* 0x3b800000 */
43
44int
45__kernel_rem_pio2f(float *x, float *y, int e0, int nx, int prec,
46 const int32_t *ipio2)
47{
48 int32_t jz,jx,jv,jp,jk,carry,n,iq[20],i,j,k,m,q0,ih;
49 float z,fw,f[20],fq[20],q[20];
50
51 /* initialize jk*/
52 jk = init_jk[prec];
53 jp = jk;
54
55 /* determine jx,jv,q0, note that 3>q0 */
56 jx = nx-1;
57 jv = (e0-3)/8; if(jv<0) jv=0;
1
Assuming 'jv' is >= 0
→
2
←
Taking false branch
→
58 q0 = e0-8*(jv+1);
59
60 /* set up f[0] to f[jx+jk] where f[jx+jk] = ipio2[jv+jk] */
61 j = jv-jx; m = jx+jk;
62 for(i=0;i<=m;i++,j++) f[i] = (j<0)? zero : (float) ipio2[j];
3
←
Assuming 'i' is > 'm'
→
4
←
Loop condition is false. Execution continues on line 65
→
63
64 /* compute q[0],q[1],...q[jk] */
65 for (i=0;i<=jk;i++) {
5
←
Assuming 'i' is > 'jk'
→
6
←
Loop condition is false. Execution continues on line 69
→
66 for(j=0,fw=0.0;j<=jx;j++) fw += x[j]*f[jx+i-j]; q[i] = fw;
67 }
68
69 jz = jk;
70recompute:
71 /* distill q[] into iq[] reversingly */
72 for(i=0,j=jz,z=q[jz];j
6.1
'j' is <= 0
>0;i++,j--) {
7
←
Loop condition is false. Execution continues on line 79
→
73 fw = (float)((int32_t)(twon8* z));
74 iq[i] = (int32_t)(z-two8*fw);
75 z = q[j-1]+fw;
76 }
77
78 /* compute n */
79 z = scalbnf(z,q0); /* actual value of z */
80 z -= (float)8.0*floorf(z*(float)0.125); /* trim off integer >= 8 */
81 n = (int32_t) z;
82 z -= (float)n;
83 ih = 0;
84 if(q0>0) { /* need iq[jz-1] to determine n */
8
←
Assuming 'q0' is <= 0
→
9
←
Taking false branch
→
85 i = (iq[jz-1]>>(8-q0)); n += i;
86 iq[jz-1] -= i<<(8-q0);
87 ih = iq[jz-1]>>(7-q0);
88 }
89 else if(q0==0) ih = iq[jz-1]>>8;
10
←
Assuming 'q0' is not equal to 0
→
11
←
Taking false branch
→
90 else if(z>=(float)0.5) ih=2;
12
←
Assuming the condition is false
→
13
←
Taking false branch
→
91
92 if(ih
13.1
'ih' is <= 0
>0) { /* q > 0.5 */
14
←
Taking false branch
→
93 n += 1; carry = 0;
94 for(i=0;i<jz ;i++) { /* compute 1-q */
95 j = iq[i];
96 if(carry==0) {
97 if(j!=0) {
98 carry = 1; iq[i] = 0x100- j;
99 }
100 } else iq[i] = 0xff - j;
101 }
102 if(q0>0) { /* rare case: chance is 1 in 12 */
103 switch(q0) {
104 case 1:
105 iq[jz-1] &= 0x7f; break;
106 case 2:
107 iq[jz-1] &= 0x3f; break;
108 }
109 }
110 if(ih==2) {
111 z = one - z;
112 if(carry!=0) z -= scalbnf(one,q0);
113 }
114 }
115
116 /* check if recomputation is needed */
117 if(z==zero) {
15
←
Assuming 'z' is not equal to 'zero'
→
16
←
Taking false branch
→
118 j = 0;
119 for (i=jz-1;i>=jk;i--) j |= iq[i];
120 if(j==0) { /* need recomputation */
121 for(k=1;iq[jk-k]==0;k++); /* k = no. of terms needed */
122
123 for(i=jz+1;i<=jz+k;i++) { /* add q[jz+1] to q[jz+k] */
124 f[jx+i] = (float) ipio2[jv+i];
125 for(j=0,fw=0.0;j<=jx;j++) fw += x[j]*f[jx+i-j];
126 q[i] = fw;
127 }
128 jz += k;
129 goto recompute;
130 }
131 }
132
133 /* chop off zero terms */
134 if(z==(float)0.0) {
17
←
Assuming the condition is false
→
18
←
Taking false branch
→
135 jz -= 1; q0 -= 8;
136 while(iq[jz]==0) { jz--; q0-=8;}
137 } else { /* break z into 8-bit if necessary */
138 z = scalbnf(z,-q0);
139 if(z>=two8) {
19
←
Assuming 'z' is >= 'two8'
→
20
←
Taking true branch
→
140 fw = (float)((int32_t)(twon8*z));
141 iq[jz] = (int32_t)(z-two8*fw);
142 jz += 1; q0 += 8;
143 iq[jz] = (int32_t) fw;
144 } else iq[jz] = (int32_t) z ;
145 }
146
147 /* convert integer "bit" chunk to floating-point value */
148 fw = scalbnf(one,q0);
149 for(i=jz;i>=0;i--) {
21
←
Assuming 'i' is >= 0
→
22
←
Loop condition is true. Entering loop body
→
23
←
Loop condition is false. Execution continues on line 154
→
150 q[i] = fw*(float)iq[i]; fw*=twon8;
151 }
152
153 /* compute PIo2[0,...,jp]*q[jz,...,0] */
154 for(i=jz;i
23.1
'i' is >= 0
>=0;i--) {
24
←
Loop condition is true. Entering loop body
→
25
←
Loop condition is false. Execution continues on line 160
→
155 for(fw=0.0,k=0;k
24.1
'k' is > 'jp'
<=jp&&k<=jz-i;k++) fw += PIo2[k]*q[i+k];
156 fq[jz-i] = fw;
157 }
158
159 /* compress fq[] into y[] */
160 switch(prec) {
26
←
Control jumps to 'case 3:' at line 175
→
161 case 0:
162 fw = 0.0;
163 for (i=jz;i>=0;i--) fw += fq[i];
164 y[0] = (ih==0)? fw: -fw;
165 break;
166 case 1:
167 case 2:
168 fw = 0.0;
169 for (i=jz;i>=0;i--) fw += fq[i];
170 y[0] = (ih==0)? fw: -fw;
171 fw = fq[0]-fw;
172 for (i=1;i<=jz;i++) fw += fq[i];
173 y[1] = (ih==0)? fw: -fw;
174 break;
175 case 3: /* painful */
176 for (i=jz;i
26.1
'i' is <= 0
>0;i--) {
27
←
Loop condition is false. Execution continues on line 181
→
177 fw = fq[i-1]+fq[i];
178 fq[i] += fq[i-1]-fw;
179 fq[i-1] = fw;
180 }
181 for (i=jz;i
27.1
'i' is <= 1
>1;i--) {
28
←
Loop condition is false. Execution continues on line 186
→
182 fw = fq[i-1]+fq[i];
183 fq[i] += fq[i-1]-fw;
184 fq[i-1] = fw;
185 }
186 for (fw=0.0,i=jz;i
28.1
'i' is < 2
>=2;i--) fw += fq[i];
29
←
Loop condition is false. Execution continues on line 187
→
187 if(ih
29.1
'ih' is equal to 0
==0) {
30
←
Taking true branch
→
188 y[0] = fq[0]; y[1] = fq[1]; y[2] = fw;
31
←
Assigned value is garbage or undefined
189 } else {
190 y[0] = -fq[0]; y[1] = -fq[1]; y[2] = -fw;
191 }
192 }
193 return n&7;
194}