Fix pow missing underflows (bug 18825).

Similar to various other bugs in this area, pow functions can fail to
raise the underflow exception when the result is tiny and inexact but
one or more low bits of the intermediate result that is scaled down
(or, in the i386 case, converted from a wider evaluation format) are
zero.  This patch forces the exception in a similar way to previous
fixes, thereby concluding the fixes for known bugs with missing
underflow exceptions currently filed in Bugzilla.

Tested for x86_64, x86, mips64 and powerpc.

	[BZ #18825]
	* sysdeps/i386/fpu/i386-math-asm.h (FLT_NARROW_EVAL_UFLOW_NONNAN):
	New macro.
	(DBL_NARROW_EVAL_UFLOW_NONNAN): Likewise.
	(LDBL_CHECK_FORCE_UFLOW_NONNAN): Likewise.
	* sysdeps/i386/fpu/e_pow.S: Use DEFINE_DBL_MIN.
	(__ieee754_pow): Use DBL_NARROW_EVAL_UFLOW_NONNAN instead of
	DBL_NARROW_EVAL, reloading the PIC register as needed.
	* sysdeps/i386/fpu/e_powf.S: Use DEFINE_FLT_MIN.
	(__ieee754_powf): Use FLT_NARROW_EVAL_UFLOW_NONNAN instead of
	FLT_NARROW_EVAL.  Use separate return path for case when first
	argument is NaN.
	* sysdeps/i386/fpu/e_powl.S: Include <i386-math-asm.h>.  Use
	DEFINE_LDBL_MIN.
	(__ieee754_powl): Use LDBL_CHECK_FORCE_UFLOW_NONNAN, reloading the
	PIC register.
	* sysdeps/ieee754/dbl-64/e_pow.c (__ieee754_pow): Use
	math_check_force_underflow_nonneg.
	* sysdeps/ieee754/flt-32/e_powf.c (__ieee754_powf): Force
	underflow for subnormal result.
	* sysdeps/ieee754/ldbl-128/e_powl.c (__ieee754_powl): Likewise.
	* sysdeps/ieee754/ldbl-128ibm/e_powl.c (__ieee754_powl): Use
	math_check_force_underflow_nonneg.
	* sysdeps/x86/fpu/powl_helper.c (__powl_helper): Use
	math_check_force_underflow.
	* sysdeps/x86_64/fpu/x86_64-math-asm.h
	(LDBL_CHECK_FORCE_UFLOW_NONNAN): New macro.
	* sysdeps/x86_64/fpu/e_powl.S: Include <x86_64-math-asm.h>.  Use
	DEFINE_LDBL_MIN.
	(__ieee754_powl): Use LDBL_CHECK_FORCE_UFLOW_NONNAN.
	* math/auto-libm-test-in: Add more tests of pow.
	* math/auto-libm-test-out: Regenerated.
This commit is contained in:
Joseph Myers 2015-09-25 22:29:10 +00:00
parent 5a9af6376d
commit 6ace393821
15 changed files with 3926 additions and 10 deletions

View File

@ -1,3 +1,38 @@
2015-09-25 Joseph Myers <joseph@codesourcery.com>
[BZ #18825]
* sysdeps/i386/fpu/i386-math-asm.h (FLT_NARROW_EVAL_UFLOW_NONNAN):
New macro.
(DBL_NARROW_EVAL_UFLOW_NONNAN): Likewise.
(LDBL_CHECK_FORCE_UFLOW_NONNAN): Likewise.
* sysdeps/i386/fpu/e_pow.S: Use DEFINE_DBL_MIN.
(__ieee754_pow): Use DBL_NARROW_EVAL_UFLOW_NONNAN instead of
DBL_NARROW_EVAL, reloading the PIC register as needed.
* sysdeps/i386/fpu/e_powf.S: Use DEFINE_FLT_MIN.
(__ieee754_powf): Use FLT_NARROW_EVAL_UFLOW_NONNAN instead of
FLT_NARROW_EVAL. Use separate return path for case when first
argument is NaN.
* sysdeps/i386/fpu/e_powl.S: Include <i386-math-asm.h>. Use
DEFINE_LDBL_MIN.
(__ieee754_powl): Use LDBL_CHECK_FORCE_UFLOW_NONNAN, reloading the
PIC register.
* sysdeps/ieee754/dbl-64/e_pow.c (__ieee754_pow): Use
math_check_force_underflow_nonneg.
* sysdeps/ieee754/flt-32/e_powf.c (__ieee754_powf): Force
underflow for subnormal result.
* sysdeps/ieee754/ldbl-128/e_powl.c (__ieee754_powl): Likewise.
* sysdeps/ieee754/ldbl-128ibm/e_powl.c (__ieee754_powl): Use
math_check_force_underflow_nonneg.
* sysdeps/x86/fpu/powl_helper.c (__powl_helper): Use
math_check_force_underflow.
* sysdeps/x86_64/fpu/x86_64-math-asm.h
(LDBL_CHECK_FORCE_UFLOW_NONNAN): New macro.
* sysdeps/x86_64/fpu/e_powl.S: Include <x86_64-math-asm.h>. Use
DEFINE_LDBL_MIN.
(__ieee754_powl): Use LDBL_CHECK_FORCE_UFLOW_NONNAN.
* math/auto-libm-test-in: Add more tests of pow.
* math/auto-libm-test-out: Regenerated.
2015-09-25 Florian Weimer <fweimer@redhat.com>
* nss/bug17079.c (init_test_items): Add diagnostic for

6
NEWS
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@ -14,9 +14,9 @@ Version 2.23
16985, 17118, 17243, 17244, 17250, 17441, 17787, 17886, 17887, 17905,
18084, 18086, 18240, 18265, 18370, 18421, 18480, 18525, 18595, 18610,
18618, 18647, 18661, 18674, 18675, 18681, 18757, 18778, 18781, 18787,
18789, 18790, 18795, 18796, 18803, 18820, 18823, 18824, 18857, 18863,
18870, 18872, 18873, 18875, 18887, 18921, 18951, 18952, 18961, 18966,
18967, 18970, 18977, 18980, 18981, 19003.
18789, 18790, 18795, 18796, 18803, 18820, 18823, 18824, 18825, 18857,
18863, 18870, 18872, 18873, 18875, 18887, 18921, 18951, 18952, 18961,
18966, 18967, 18970, 18977, 18980, 18981, 19003.
* The obsolete header <regexp.h> has been removed. Programs that require
this header must be updated to use <regex.h> instead.

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@ -3067,6 +3067,151 @@ pow 1.01 -min_subnorm
pow 2.0 -100000.0
pow 2 -126.125
pow 2 -126.25
pow 2 -126.375
pow 2 -126.5
pow 2 -126.625
pow 2 -126.75
pow 2 -126.875
pow 2 -969.125
pow 2 -969.25
pow 2 -969.375
pow 2 -969.5
pow 2 -969.625
pow 2 -969.75
pow 2 -969.875
pow 2 -1022.125
pow 2 -1022.25
pow 2 -1022.375
pow 2 -1022.5
pow 2 -1022.625
pow 2 -1022.75
pow 2 -1022.875
pow 2 -16382.125
pow 2 -16382.25
pow 2 -16382.375
pow 2 -16382.5
pow 2 -16382.625
pow 2 -16382.75
pow 2 -16382.875
pow 2 -16383.125
pow 2 -16383.25
pow 2 -16383.375
pow 2 -16383.5
pow 2 -16383.625
pow 2 -16383.75
pow 2 -16383.875
pow 0.5 126.125
pow 0.5 126.25
pow 0.5 126.375
pow 0.5 126.5
pow 0.5 126.625
pow 0.5 126.75
pow 0.5 126.875
pow 0.5 969.125
pow 0.5 969.25
pow 0.5 969.375
pow 0.5 969.5
pow 0.5 969.625
pow 0.5 969.75
pow 0.5 969.875
pow 0.5 1022.125
pow 0.5 1022.25
pow 0.5 1022.375
pow 0.5 1022.5
pow 0.5 1022.625
pow 0.5 1022.75
pow 0.5 1022.875
pow 0.5 16382.125
pow 0.5 16382.25
pow 0.5 16382.375
pow 0.5 16382.5
pow 0.5 16382.625
pow 0.5 16382.75
pow 0.5 16382.875
pow 0.5 16383.125
pow 0.5 16383.25
pow 0.5 16383.375
pow 0.5 16383.5
pow 0.5 16383.625
pow 0.5 16383.75
pow 0.5 16383.875
pow 0x1.00001p1 -126
pow -0x1.00002p1 -126
pow 0x1.00003p1 -126
pow -0x1.00004p1 -126
pow 0x1.00005p1 -126
pow -0x1.00006p1 -126
pow 0x1.00007p1 -126
pow 0x1.00001p1 -969
pow -0x1.00002p1 -969
pow 0x1.00003p1 -969
pow -0x1.00004p1 -969
pow 0x1.00005p1 -969
pow -0x1.00006p1 -969
pow 0x1.00007p1 -969
pow 0x1.00001p1 -1022
pow -0x1.00002p1 -1022
pow 0x1.00003p1 -1022
pow -0x1.00004p1 -1022
pow 0x1.00005p1 -1022
pow -0x1.00006p1 -1022
pow 0x1.00007p1 -1022
pow 0x1.00001p1 -16382
pow -0x1.00002p1 -16382
pow 0x1.00003p1 -16382
pow -0x1.00004p1 -16382
pow 0x1.00005p1 -16382
pow -0x1.00006p1 -16382
pow 0x1.00007p1 -16382
pow 0x1.00001p1 -16383
pow -0x1.00002p1 -16383
pow 0x1.00003p1 -16383
pow -0x1.00004p1 -16383
pow 0x1.00005p1 -16383
pow -0x1.00006p1 -16383
pow 0x1.00007p1 -16383
pow 0x0.ffff1p-1 126
pow -0x0.ffff2p-1 126
pow 0x0.ffff3p-1 126
pow -0x0.ffff4p-1 126
pow 0x0.ffff5p-1 126
pow -0x0.ffff6p-1 126
pow 0x0.ffff7p-1 126
pow 0x0.ffff1p-1 969
pow -0x0.ffff2p-1 969
pow 0x0.ffff3p-1 969
pow -0x0.ffff4p-1 969
pow 0x0.ffff5p-1 969
pow -0x0.ffff6p-1 969
pow 0x0.ffff7p-1 969
pow 0x0.ffff1p-1 1022
pow -0x0.ffff2p-1 1022
pow 0x0.ffff3p-1 1022
pow -0x0.ffff4p-1 1022
pow 0x0.ffff5p-1 1022
pow -0x0.ffff6p-1 1022
pow 0x0.ffff7p-1 1022
pow 0x0.ffff1p-1 16382
pow -0x0.ffff2p-1 16382
pow 0x0.ffff3p-1 16382
pow -0x0.ffff4p-1 16382
pow 0x0.ffff5p-1 16382
pow -0x0.ffff6p-1 16382
pow 0x0.ffff7p-1 16382
pow 0x0.ffff1p-1 16383
pow -0x0.ffff2p-1 16383
pow 0x0.ffff3p-1 16383
pow -0x0.ffff4p-1 16383
pow 0x0.ffff5p-1 16383
pow -0x0.ffff6p-1 16383
pow 0x0.ffff7p-1 16383
pow 0x2.000b3p0 -1022
pow 0x2.000582p0 -1022
pow 2 -0x3.fe513p+8
pow 2 -0x3.fe4e8p+8
pow 1.0625 1.125
pow 1.5 1.03125
pow 0x1.7d1a0a6f2p+681 1.5

File diff suppressed because it is too large Load Diff

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@ -54,6 +54,7 @@ minfinity:
mzero:
.byte 0, 0, 0, 0, 0, 0, 0, 0x80
ASM_SIZE_DIRECTIVE(minf_mzero)
DEFINE_DBL_MIN
#ifdef PIC
# define MO(op) op##@GOTOFF(%ecx)
@ -166,7 +167,10 @@ ENTRY(__ieee754_pow)
orl %edx, %ecx
jnz 6b
fstp %st(0) // ST*x
DBL_NARROW_EVAL
#ifdef PIC
LOAD_PIC_REG (cx)
#endif
DBL_NARROW_EVAL_UFLOW_NONNAN
ret
/* y is ±NAN */
@ -259,7 +263,7 @@ ENTRY(__ieee754_pow)
cfi_adjust_cfa_offset (-8)
292: fscale // +/- 2^fract(y*log2(x))*2^int(y*log2(x)) : int(y*log2(x))
fstp %st(1) // +/- 2^fract(y*log2(x))*2^int(y*log2(x))
DBL_NARROW_EVAL
DBL_NARROW_EVAL_UFLOW_NONNAN
ret

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@ -51,6 +51,7 @@ minfinity:
mzero:
.byte 0, 0, 0, 0, 0, 0, 0, 0x80
ASM_SIZE_DIRECTIVE(minf_mzero)
DEFINE_FLT_MIN
#ifdef PIC
# define MO(op) op##@GOTOFF(%ecx)
@ -97,7 +98,7 @@ ENTRY(__ieee754_powf)
je 15f // x is ±inf
cmpb $0x01, %ah
je 32f // x is NaN
je 33f // x is NaN
fxch // y : x
@ -149,7 +150,7 @@ ENTRY(__ieee754_powf)
testl %edx, %edx
jnz 6b
fstp %st(0) // ST*x
FLT_NARROW_EVAL
FLT_NARROW_EVAL_UFLOW_NONNAN
ret
/* y is ±NAN */
@ -198,9 +199,15 @@ ENTRY(__ieee754_powf)
32: addl $4, %esp
cfi_adjust_cfa_offset (-4)
fstp %st(1) // 2^fract(y*log2(x))*2^int(y*log2(x))
FLT_NARROW_EVAL
FLT_NARROW_EVAL_UFLOW_NONNAN
ret
/* x is NaN. */
cfi_adjust_cfa_offset (4)
33: addl $4, %esp
cfi_adjust_cfa_offset (-4)
fstp %st(1)
ret
// pow(x,±0) = 1
.align ALIGNARG(4)

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@ -18,6 +18,7 @@
<http://www.gnu.org/licenses/>. */
#include <machine/asm.h>
#include <i386-math-asm.h>
.section .rodata.cst8,"aM",@progbits,8
@ -59,6 +60,7 @@ minfinity:
mzero:
.byte 0, 0, 0, 0, 0, 0, 0, 0x80
ASM_SIZE_DIRECTIVE(minf_mzero)
DEFINE_LDBL_MIN
#ifdef PIC
# define MO(op) op##@GOTOFF(%ecx)
@ -187,6 +189,10 @@ ENTRY(__ieee754_powl)
orl %edx, %ecx
jnz 6b
fstp %st(0) // ST*x
#ifdef PIC
LOAD_PIC_REG (cx)
#endif
LDBL_CHECK_FORCE_UFLOW_NONNAN
ret
/* y is ±NAN */

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@ -131,6 +131,40 @@ ldbl_min: \
addl $8, %esp; \
cfi_adjust_cfa_offset (-8);
/* Likewise, but the non-NaN argument may be negative. */
#define FLT_NARROW_EVAL_UFLOW_NONNAN \
subl $4, %esp; \
cfi_adjust_cfa_offset (4); \
fld %st(0); \
fabs; \
fcomps MO(flt_min); \
fnstsw; \
sahf; \
jnc 6424f; \
fld %st(0); \
fmul %st(0); \
fstps (%esp); \
6424: fstps (%esp); \
flds (%esp); \
addl $4, %esp; \
cfi_adjust_cfa_offset (-4);
#define DBL_NARROW_EVAL_UFLOW_NONNAN \
subl $8, %esp; \
cfi_adjust_cfa_offset (8); \
fld %st(0); \
fabs; \
fcompl MO(dbl_min); \
fnstsw; \
sahf; \
jnc 6453f; \
fld %st(0); \
fmul %st(0); \
fstpl (%esp); \
6453: fstpl (%esp); \
fldl (%esp); \
addl $8, %esp; \
cfi_adjust_cfa_offset (-8);
/* Force an underflow exception if the given value is subnormal. The
relevant constant for the minimum of the type must have been
defined, the MO macro must have been defined for access to memory
@ -251,6 +285,18 @@ ldbl_min: \
addl $8, %esp; \
cfi_adjust_cfa_offset (-8); \
6453:
#define LDBL_CHECK_FORCE_UFLOW_NONNAN \
fldt MO(ldbl_min); \
fld %st(1); \
fabs; \
fcompp; \
fnstsw; \
sahf; \
jnc 6464f; \
fld %st(0); \
fmul %st(0); \
fstp %st(0); \
6464:
/* Likewise, but the argument is nonnegative and not a NaN. */
#define FLT_CHECK_FORCE_UFLOW_NONNEG \

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@ -119,6 +119,8 @@ __ieee754_pow (double x, double y)
retval = huge * huge;
else if (retval == 0)
retval = tiny * tiny;
else
math_check_force_underflow_nonneg (retval);
return retval;
}

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@ -244,7 +244,12 @@ __ieee754_powf(float x, float y)
z = one-(r-z);
GET_FLOAT_WORD(j,z);
j += (n<<23);
if((j>>23)<=0) z = __scalbnf(z,n); /* subnormal output */
if((j>>23)<=0) /* subnormal output */
{
z = __scalbnf (z, n);
float force_underflow = z * z;
math_force_eval (force_underflow);
}
else SET_FLOAT_WORD(z,j);
return s*z;
}

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@ -435,7 +435,11 @@ __ieee754_powl (long double x, long double y)
j = o.parts32.w0;
j += (n << 16);
if ((j >> 16) <= 0)
z = __scalbnl (z, n); /* subnormal output */
{
z = __scalbnl (z, n); /* subnormal output */
long double force_underflow = z * z;
math_force_eval (force_underflow);
}
else
{
o.parts32.w0 = j;

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@ -409,6 +409,7 @@ __ieee754_powl (long double x, long double y)
r = (z * t1) / (t1 - two) - (w + z * w);
z = one - (r - z);
z = __scalbnl (z, n);
math_check_force_underflow_nonneg (z);
return s * z;
}
strong_alias (__ieee754_powl, __powl_finite)

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@ -229,6 +229,7 @@ __powl_helper (long double x, long double y)
if (negate)
res = -res;
asm ("fscale" : "=t" (res) : "0" (res), "u" (log2_res_int));
math_check_force_underflow (res);
return res;
}

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@ -18,6 +18,7 @@
<http://www.gnu.org/licenses/>. */
#include <machine/asm.h>
#include <x86_64-math-asm.h>
.section .rodata.cst8,"aM",@progbits,8
@ -59,6 +60,7 @@ minfinity:
mzero:
.byte 0, 0, 0, 0, 0, 0, 0, 0x80
ASM_SIZE_DIRECTIVE(minf_mzero)
DEFINE_LDBL_MIN
#ifdef PIC
# define MO(op) op##(%rip)
@ -175,6 +177,7 @@ ENTRY(__ieee754_powl)
orl %edx, %ecx
jnz 6b
fstp %st(0) // ST*x
LDBL_CHECK_FORCE_UFLOW_NONNAN
ret
/* y is ±NAN */

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@ -46,6 +46,19 @@ ldbl_min: \
fstp %st(0); \
6464:
/* Likewise, but the argument is not a NaN. */
#define LDBL_CHECK_FORCE_UFLOW_NONNAN \
fldt MO(ldbl_min); \
fld %st(1); \
fabs; \
fcomip %st(1), %st(0); \
fstp %st(0); \
jnc 6464f; \
fld %st(0); \
fmul %st(0); \
fstp %st(0); \
6464:
/* Likewise, but the argument is nonnegative and not a NaN. */
#define LDBL_CHECK_FORCE_UFLOW_NONNEG \
fldt MO(ldbl_min); \