Bug Summary

File:src/lib/libm/src/e_fmodf.c
Warning:line 92, column 37
The result of the left shift is undefined because the left operand is negative

Annotated Source Code

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clang -cc1 -cc1 -triple amd64-unknown-openbsd7.4 -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name e_fmodf.c -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 -pic-is-pie -mframe-pointer=all -relaxed-aliasing -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -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/llvm16/lib/clang/16 -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 -internal-isystem /usr/local/llvm16/lib/clang/16/include -internal-externc-isystem /usr/include -O2 -fdebug-compilation-dir=/usr/src/lib/libm/obj -ferror-limit 19 -fwrapv -D_RET_PROTECTOR -ret-protector -fcf-protection=branch -fno-jump-tables -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/scan/2024-01-11-140451-98009-1 -x c /usr/src/lib/libm/src/e_fmodf.c
1/* e_fmodf.c -- float version of e_fmod.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/*
17 * fmodf(x,y)
18 * Return x mod y in exact arithmetic
19 * Method: shift and subtract
20 */
21
22#include "math.h"
23#include "math_private.h"
24
25static const float one = 1.0, Zero[] = {0.0, -0.0,};
26
27float
28fmodf(float x, float y)
29{
30 int32_t n,hx,hy,hz,ix,iy,sx,i;
31
32 GET_FLOAT_WORD(hx,x)do { ieee_float_shape_type gf_u; gf_u.value = (x); (hx) = gf_u
.word; } while (0);
1
Loop condition is false. Exiting loop
→
33 GET_FLOAT_WORD(hy,y)do { ieee_float_shape_type gf_u; gf_u.value = (y); (hy) = gf_u
.word; } while (0);
2
←
Loop condition is false. Exiting loop
→
34 sx = hx&0x80000000; /* sign of x */
35 hx ^=sx; /* |x| */
36 hy &= 0x7fffffff; /* |y| */
37
38 /* purge off exception values */
39 if(hy==0||(hx>=0x7f800000)|| /* y=0,or x not finite */
3
←
Assuming 'hy' is not equal to 0
→
4
←
Assuming 'hx' is < 2139095040
→
6
←
Taking false branch
→
40 (hy>0x7f800000)) /* or y is NaN */
5
←
Assuming 'hy' is <= 2139095040
→
41 return (x*y)/(x*y);
42 if(hx<hy) return x; /* |x|<|y| return x */
7
←
Assuming 'hx' is >= 'hy'
→
8
←
Taking false branch
→
43 if(hx==hy)
9
←
Assuming 'hx' is not equal to 'hy'
→
10
←
Taking false branch
→
44 return Zero[(u_int32_t)sx>>31]; /* |x|=|y| return x*0*/
45
46 /* determine ix = ilogb(x) */
47 if(hx<0x00800000) { /* subnormal x */
11
←
Assuming 'hx' is >= 8388608
→
12
←
Taking false branch
→
48 for (ix = -126,i=(hx<<8); i>0; i<<=1) ix -=1;
49 } else ix = (hx>>23)-127;
50
51 /* determine iy = ilogb(y) */
52 if(hy<0x00800000) { /* subnormal y */
13
←
Assuming 'hy' is >= 8388608
→
14
←
Taking false branch
→
53 for (iy = -126,i=(hy<<8); i>=0; i<<=1) iy -=1;
54 } else iy = (hy>>23)-127;
55
56 /* set up {hx,lx}, {hy,ly} and align y to x */
57 if(ix >= -126)
15
←
Assuming the condition is false
→
16
←
Taking false branch
→
58 hx = 0x00800000|(0x007fffff&hx);
59 else { /* subnormal x, shift x to normal */
60 n = -126-ix;
61 hx = hx<<n;
62 }
63 if(iy >= -126)
17
←
Assuming the condition is false
→
18
←
Taking false branch
→
64 hy = 0x00800000|(0x007fffff&hy);
65 else { /* subnormal y, shift y to normal */
66 n = -126-iy;
67 hy = hy<<n;
68 }
69
70 /* fix point fmod */
71 n = ix - iy;
72 while(n--) {
19
←
Loop condition is false. Execution continues on line 81
→
73 hz=hx-hy;
74 if(hz<0){hx = hx+hx;}
75 else {
76 if(hz==0) /* return sign(x)*0 */
77 return Zero[(u_int32_t)sx>>31];
78 hx = hz+hz;
79 }
80 }
81 hz=hx-hy;
82 if(hz>=0) {hx=hz;}
20
←
Assuming 'hz' is < 0
→
21
←
Taking false branch
→
83
84 /* convert back to floating value and restore the sign */
85 if(hx==0) /* return sign(x)*0 */
22
←
Assuming 'hx' is not equal to 0
→
23
←
Taking false branch
→
86 return Zero[(u_int32_t)sx>>31];
87 while(hx<0x00800000) { /* normalize x */
24
←
Assuming 'hx' is < 8388608
→
25
←
Loop condition is true. Entering loop body
→
26
←
Assuming 'hx' is >= 8388608
→
27
←
Loop condition is false. Execution continues on line 91
→
88 hx = hx+hx;
89 iy -= 1;
90 }
91 if(iy>= -126) { /* normalize output */
28
←
Assuming the condition is true
→
29
←
Taking true branch
→
92 hx = ((hx-0x00800000)|((iy+127)<<23));
30
←
The result of the left shift is undefined because the left operand is negative
93 SET_FLOAT_WORD(x,hx|sx)do { ieee_float_shape_type sf_u; sf_u.word = (hx|sx); (x) = sf_u
.value; } while (0);
94 } else { /* subnormal output */
95 n = -126 - iy;
96 hx >>= n;
97 SET_FLOAT_WORD(x,hx|sx)do { ieee_float_shape_type sf_u; sf_u.word = (hx|sx); (x) = sf_u
.value; } while (0);
98 x *= one; /* create necessary signal */
99 }
100 return x; /* exact output */
101}
102DEF_STD(fmodf)__asm__(".global " "fmodf" " ; " "fmodf" " = " "_libm_fmodf");