Bug Summary

File:src/lib/libm/src/e_rem_pio2.c
Warning:line 133, column 2
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 e_rem_pio2.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/e_rem_pio2.c
1/* @(#)e_rem_pio2.c 5.1 93/09/24 */
2/*
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5 *
6 * Developed at SunPro, a Sun Microsystems, Inc. business.
7 * Permission to use, copy, modify, and distribute this
8 * software is freely granted, provided that this notice
9 * is preserved.
10 * ====================================================
11 */
12
13/* __ieee754_rem_pio2(x,y)
14 *
15 * return the remainder of x rem pi/2 in y[0]+y[1]
16 * use __kernel_rem_pio2()
17 */
18
19#include "math.h"
20#include "math_private.h"
21
22static const int32_t npio2_hw[] = {
230x3FF921FB, 0x400921FB, 0x4012D97C, 0x401921FB, 0x401F6A7A, 0x4022D97C,
240x4025FDBB, 0x402921FB, 0x402C463A, 0x402F6A7A, 0x4031475C, 0x4032D97C,
250x40346B9C, 0x4035FDBB, 0x40378FDB, 0x403921FB, 0x403AB41B, 0x403C463A,
260x403DD85A, 0x403F6A7A, 0x40407E4C, 0x4041475C, 0x4042106C, 0x4042D97C,
270x4043A28C, 0x40446B9C, 0x404534AC, 0x4045FDBB, 0x4046C6CB, 0x40478FDB,
280x404858EB, 0x404921FB,
29};
30
31/*
32 * invpio2: 53 bits of 2/pi
33 * pio2_1: first 33 bit of pi/2
34 * pio2_1t: pi/2 - pio2_1
35 * pio2_2: second 33 bit of pi/2
36 * pio2_2t: pi/2 - (pio2_1+pio2_2)
37 * pio2_3: third 33 bit of pi/2
38 * pio2_3t: pi/2 - (pio2_1+pio2_2+pio2_3)
39 */
40
41static const double
42zero = 0.00000000000000000000e+00, /* 0x00000000, 0x00000000 */
43half = 5.00000000000000000000e-01, /* 0x3FE00000, 0x00000000 */
44two24 = 1.67772160000000000000e+07, /* 0x41700000, 0x00000000 */
45invpio2 = 6.36619772367581382433e-01, /* 0x3FE45F30, 0x6DC9C883 */
46pio2_1 = 1.57079632673412561417e+00, /* 0x3FF921FB, 0x54400000 */
47pio2_1t = 6.07710050650619224932e-11, /* 0x3DD0B461, 0x1A626331 */
48pio2_2 = 6.07710050630396597660e-11, /* 0x3DD0B461, 0x1A600000 */
49pio2_2t = 2.02226624879595063154e-21, /* 0x3BA3198A, 0x2E037073 */
50pio2_3 = 2.02226624871116645580e-21, /* 0x3BA3198A, 0x2E000000 */
51pio2_3t = 8.47842766036889956997e-32; /* 0x397B839A, 0x252049C1 */
52
53int32_t
54__ieee754_rem_pio2(double x, double *y)
55{
56 double z,w,t,r,fn;
1
'z' declared without an initial value
→
57 double tx[3];
58 int32_t e0,i,j,nx,n,ix,hx;
59 u_int32_t low;
60
61 GET_HIGH_WORD(hx,x)do { ieee_double_shape_type gh_u; gh_u.value = (x); (hx) = gh_u
.parts.msw; } while (0); /* high word of x */
2
←
Loop condition is false. Exiting loop
→
62 ix = hx&0x7fffffff;
63 if(ix<=0x3fe921fb) /* |x| ~<= pi/4 , no need for reduction */
3
←
Assuming 'ix' is > 1072243195
→
4
←
Taking false branch
→
64 {y[0] = x; y[1] = 0; return 0;}
65 if(ix<0x4002d97c) { /* |x| < 3pi/4, special case with n=+-1 */
5
←
Assuming 'ix' is >= 1073928572
→
6
←
Taking false branch
→
66 if(hx>0) {
67 z = x - pio2_1;
68 if(ix!=0x3ff921fb) { /* 33+53 bit pi is good enough */
69 y[0] = z - pio2_1t;
70 y[1] = (z-y[0])-pio2_1t;
71 } else { /* near pi/2, use 33+33+53 bit pi */
72 z -= pio2_2;
73 y[0] = z - pio2_2t;
74 y[1] = (z-y[0])-pio2_2t;
75 }
76 return 1;
77 } else { /* negative x */
78 z = x + pio2_1;
79 if(ix!=0x3ff921fb) { /* 33+53 bit pi is good enough */
80 y[0] = z + pio2_1t;
81 y[1] = (z-y[0])+pio2_1t;
82 } else { /* near pi/2, use 33+33+53 bit pi */
83 z += pio2_2;
84 y[0] = z + pio2_2t;
85 y[1] = (z-y[0])+pio2_2t;
86 }
87 return -1;
88 }
89 }
90 if(ix<=0x413921fb) { /* |x| ~<= 2^19*(pi/2), medium size */
7
←
Assuming 'ix' is > 1094263291
→
8
←
Taking false branch
→
91 t = fabs(x);
92 n = (int32_t) (t*invpio2+half);
93 fn = (double)n;
94 r = t-fn*pio2_1;
95 w = fn*pio2_1t; /* 1st round good to 85 bit */
96 if(n<32&&ix!=npio2_hw[n-1]) {
97 y[0] = r-w; /* quick check no cancellation */
98 } else {
99 u_int32_t high;
100 j = ix>>20;
101 y[0] = r-w;
102 GET_HIGH_WORD(high,y[0])do { ieee_double_shape_type gh_u; gh_u.value = (y[0]); (high)
= gh_u.parts.msw; } while (0);
103 i = j-((high>>20)&0x7ff);
104 if(i>16) { /* 2nd iteration needed, good to 118 */
105 t = r;
106 w = fn*pio2_2;
107 r = t-w;
108 w = fn*pio2_2t-((t-r)-w);
109 y[0] = r-w;
110 GET_HIGH_WORD(high,y[0])do { ieee_double_shape_type gh_u; gh_u.value = (y[0]); (high)
= gh_u.parts.msw; } while (0);
111 i = j-((high>>20)&0x7ff);
112 if(i>49) { /* 3rd iteration need, 151 bits acc */
113 t = r; /* will cover all possible cases */
114 w = fn*pio2_3;
115 r = t-w;
116 w = fn*pio2_3t-((t-r)-w);
117 y[0] = r-w;
118 }
119 }
120 }
121 y[1] = (r-y[0])-w;
122 if(hx<0) {y[0] = -y[0]; y[1] = -y[1]; return -n;}
123 else return n;
124 }
125 /*
126 * all other (large) arguments
127 */
128 if(ix>=0x7ff00000) { /* x is inf or NaN */
9
←
Assuming 'ix' is < 2146435072
→
10
←
Taking false branch
→
129 y[0]=y[1]=x-x; return 0;
130 }
131 /* set z = scalbn(|x|,ilogb(x)-23) */
132 GET_LOW_WORD(low,x)do { ieee_double_shape_type gl_u; gl_u.value = (x); (low) = gl_u
.parts.lsw; } while (0);
11
←
Loop condition is false. Exiting loop
→
133 SET_LOW_WORD(z,low)do { ieee_double_shape_type sl_u; sl_u.value = (z); sl_u.parts
.lsw = (low); (z) = sl_u.value; } while (0);
12
←
Assigned value is garbage or undefined
134 e0 = (ix>>20)-1046; /* e0 = ilogb(z)-23; */
135 SET_HIGH_WORD(z, ix - ((int32_t)(e0<<20)))do { ieee_double_shape_type sh_u; sh_u.value = (z); sh_u.parts
.msw = (ix - ((int32_t)(e0<<20))); (z) = sh_u.value; } while
(0);
136 for(i=0;i<2;i++) {
137 tx[i] = (double)((int32_t)(z));
138 z = (z-tx[i])*two24;
139 }
140 tx[2] = z;
141 nx = 3;
142 while(tx[nx-1]==zero) nx--; /* skip zero term */
143 n = __kernel_rem_pio2(tx,y,e0,nx,2);
144 if(hx<0) {y[0] = -y[0]; y[1] = -y[1]; return -n;}
145 return n;
146}