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author | Joseph Myers <joseph@codesourcery.com> | 2015-09-24 22:25:30 +0000 |
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committer | Joseph Myers <joseph@codesourcery.com> | 2015-09-24 22:25:30 +0000 |
commit | b2a64460ba9aca39e92731da67cc6344acb483bc (patch) | |
tree | 213e279495212accf939a0d03c10e16c131963cc /sysdeps/x86_64/fpu/x86_64-math-asm.h | |
parent | 1a19b8894f93878f99025096ec1d3b6af7db6f78 (diff) | |
download | glibc-b2a64460ba9aca39e92731da67cc6344acb483bc.tar.gz glibc-b2a64460ba9aca39e92731da67cc6344acb483bc.tar.xz glibc-b2a64460ba9aca39e92731da67cc6344acb483bc.zip |
Refactor x86_64 libm code forcing underflow exceptions.
This patch refactors code in sysdeps/x86_64/fpu that forces underflow exceptions and closely follows corresponding i386 code to use common macros in x86_64-math-asm.h for that purpose. This is mainly about keeping the code similar to the i386 code as far as possible, since each macro apart from DEFINE_LDBL_MIN ends up used only once. It would be possible to do a further refactoring to share these macros between i386 and x86_64 (with i386 using the fcomip / fucomip versions when building for i686 and above), but I have no immediate plans to do so. Tested for x86_64. * sysdeps/x86_64/fpu/x86_64-math-asm.h: New file. * sysdeps/x86_64/fpu/e_exp2l.S: Include <x86_64-math-asm.h>. (ldbl_min): Replace with use of DEFINE_LDBL_MIN. (__ieee754_exp2l): Use LDBL_CHECK_FORCE_UFLOW_NONNEG_NAN. * sysdeps/x86_64/fpu/e_expl.S: Include <x86_64-math-asm.h>. [!USE_AS_EXPM1L] (cmin): Replace with use of DEFINE_LDBL_MIN. (IEEE754_EXPL): Use LDBL_CHECK_FORCE_UFLOW_NONNEG.
Diffstat (limited to 'sysdeps/x86_64/fpu/x86_64-math-asm.h')
-rw-r--r-- | sysdeps/x86_64/fpu/x86_64-math-asm.h | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/sysdeps/x86_64/fpu/x86_64-math-asm.h b/sysdeps/x86_64/fpu/x86_64-math-asm.h new file mode 100644 index 0000000000..07eecf7079 --- /dev/null +++ b/sysdeps/x86_64/fpu/x86_64-math-asm.h @@ -0,0 +1,61 @@ +/* Helper macros for x86_64 libm functions. + Copyright (C) 2015 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#ifndef _X86_64_MATH_ASM_H +#define _X86_64_MATH_ASM_H 1 + +/* Define constants for the minimum value of a floating-point + type. */ +#define DEFINE_LDBL_MIN \ + .section .rodata.cst16,"aM",@progbits,16; \ + .p2align 4; \ + .type ldbl_min,@object; \ +ldbl_min: \ + .byte 0, 0, 0, 0, 0, 0, 0, 0x80, 0x1, 0; \ + .byte 0, 0, 0, 0, 0, 0; \ + .size ldbl_min, .-ldbl_min; + +/* Force an underflow exception if the given value (nonnegative or + NaN) 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 operands, and, if PIC, the PIC register must + have been loaded. */ +#define LDBL_CHECK_FORCE_UFLOW_NONNEG_NAN \ + fldt MO(ldbl_min); \ + fld %st(1); \ + fucomip %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); \ + fld %st(1); \ + fcomip %st(1), %st(0); \ + fstp %st(0); \ + jnc 6464f; \ + fld %st(0); \ + fmul %st(0); \ + fstp %st(0); \ +6464: + +#endif /* x86_64-math-asm.h. */ |