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| author | Joseph Myers <joseph@codesourcery.com> | 2015-09-25 22:29:10 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2015-09-25 22:29:10 +0000 |
| commit | 6ace39382120dd0668b2168591611f71b04ac8f3 (patch) | |
| tree | 2cee18351450bd4f9586f033cae63aa4d1ec8d4d /sysdeps/x86_64 | |
| parent | 5a9af6376d43b58c6545feb86002812a57956654 (diff) | |
| download | glibc-6ace39382120dd0668b2168591611f71b04ac8f3.zip glibc-6ace39382120dd0668b2168591611f71b04ac8f3.tar.gz glibc-6ace39382120dd0668b2168591611f71b04ac8f3.tar.bz2 | |
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.
Diffstat (limited to 'sysdeps/x86_64')
| -rw-r--r-- | sysdeps/x86_64/fpu/e_powl.S | 3 | ||||
| -rw-r--r-- | sysdeps/x86_64/fpu/x86_64-math-asm.h | 13 |
2 files changed, 16 insertions, 0 deletions
diff --git a/sysdeps/x86_64/fpu/e_powl.S b/sysdeps/x86_64/fpu/e_powl.S index 358abb8..a44c311 100644 --- a/sysdeps/x86_64/fpu/e_powl.S +++ b/sysdeps/x86_64/fpu/e_powl.S @@ -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 */ diff --git a/sysdeps/x86_64/fpu/x86_64-math-asm.h b/sysdeps/x86_64/fpu/x86_64-math-asm.h index 07eecf7..b548251 100644 --- a/sysdeps/x86_64/fpu/x86_64-math-asm.h +++ b/sysdeps/x86_64/fpu/x86_64-math-asm.h @@ -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); \ |