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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.
This commit is contained in:
Joseph Myers
parent
1a19b8894f
commit
b2a64460ba
@ -1,5 +1,13 @@
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2015-09-24 Joseph Myers <joseph@codesourcery.com>
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* sysdeps/x86_64/fpu/x86_64-math-asm.h: New file.
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* sysdeps/x86_64/fpu/e_exp2l.S: Include <x86_64-math-asm.h>.
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(ldbl_min): Replace with use of DEFINE_LDBL_MIN.
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(__ieee754_exp2l): Use LDBL_CHECK_FORCE_UFLOW_NONNEG_NAN.
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* sysdeps/x86_64/fpu/e_expl.S: Include <x86_64-math-asm.h>.
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[!USE_AS_EXPM1L] (cmin): Replace with use of DEFINE_LDBL_MIN.
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(IEEE754_EXPL): Use LDBL_CHECK_FORCE_UFLOW_NONNEG.
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* sysdeps/i386/fpu/e_atanh.S (__ieee754_atanh) [PIC]: Use
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LOAD_PIC_REG.
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@ -6,13 +6,9 @@
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*/
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#include <machine/asm.h>
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#include <x86_64-math-asm.h>
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.section .rodata.cst16,"aM",@progbits,16
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.p2align 4
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.type ldbl_min,@object
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ldbl_min: .byte 0, 0, 0, 0, 0, 0, 0, 0x80, 0x1, 0
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.byte 0, 0, 0, 0, 0, 0
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ASM_SIZE_DIRECTIVE(ldbl_min)
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DEFINE_LDBL_MIN
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#ifdef PIC
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# define MO(op) op##(%rip)
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@ -50,16 +46,8 @@ ENTRY(__ieee754_exp2l)
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faddp /* 2^(fract(x)) */
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fscale /* e^x */
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fstp %st(1)
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/* Ensure underflow for tiny result. */
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fldt MO(ldbl_min)
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fld %st(1)
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fucomip %st(1), %st
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fstp %st
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jnc 4f
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fld %st
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fmul %st
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fstp %st
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4: ret
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LDBL_CHECK_FORCE_UFLOW_NONNEG_NAN
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ret
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1: testl $0x200, %eax /* Test sign. */
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jz 2f /* If positive, jump. */
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@ -23,6 +23,7 @@
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*/
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#include <machine/asm.h>
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#include <x86_64-math-asm.h>
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#ifdef USE_AS_EXP10L
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# define IEEE754_EXPL __ieee754_exp10l
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@ -65,10 +66,7 @@ c1: .byte 0x20, 0xfa, 0xee, 0xc2, 0x5f, 0x70, 0xa5, 0xec, 0xed, 0x3f
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csat: .byte 0, 0, 0, 0, 0, 0, 0, 0x80, 0x0e, 0x40
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.byte 0, 0, 0, 0, 0, 0
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ASM_SIZE_DIRECTIVE(csat)
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.type cmin,@object
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cmin: .byte 0, 0, 0, 0, 0, 0, 0, 0x80, 0x1, 0
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.byte 0, 0, 0, 0, 0, 0
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ASM_SIZE_DIRECTIVE(cmin)
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DEFINE_LDBL_MIN
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#endif
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#ifdef PIC
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@ -192,17 +190,9 @@ ENTRY(IEEE754_EXPL)
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fstp %st(1) /* 2 */
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fscale /* 2 scale factor is st(1); base^x */
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fstp %st(1) /* 1 */
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/* Ensure underflow for tiny result. */
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fldt MO(cmin) /* 2 cmin */
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fld %st(1) /* 3 */
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fcomip %st(1), %st /* 2 */
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fstp %st /* 1 */
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jnc 6f
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fld %st
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fmul %st
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fstp %st
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LDBL_CHECK_FORCE_UFLOW_NONNEG
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#endif
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6: fstp %st(1) /* 0 */
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fstp %st(1) /* 0 */
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jmp 2f
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1:
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#ifdef USE_AS_EXPM1L
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61
sysdeps/x86_64/fpu/x86_64-math-asm.h
Normal file
61
sysdeps/x86_64/fpu/x86_64-math-asm.h
Normal file
@ -0,0 +1,61 @@
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/* Helper macros for x86_64 libm functions.
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Copyright (C) 2015 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _X86_64_MATH_ASM_H
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#define _X86_64_MATH_ASM_H 1
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/* Define constants for the minimum value of a floating-point
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type. */
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#define DEFINE_LDBL_MIN \
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.section .rodata.cst16,"aM",@progbits,16; \
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.p2align 4; \
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.type ldbl_min,@object; \
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ldbl_min: \
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.byte 0, 0, 0, 0, 0, 0, 0, 0x80, 0x1, 0; \
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.byte 0, 0, 0, 0, 0, 0; \
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.size ldbl_min, .-ldbl_min;
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/* Force an underflow exception if the given value (nonnegative or
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NaN) is subnormal. The relevant constant for the minimum of the
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type must have been defined, the MO macro must have been defined
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for access to memory operands, and, if PIC, the PIC register must
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have been loaded. */
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#define LDBL_CHECK_FORCE_UFLOW_NONNEG_NAN \
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fldt MO(ldbl_min); \
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fld %st(1); \
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fucomip %st(1), %st(0); \
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fstp %st(0); \
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jnc 6464f; \
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fld %st(0); \
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fmul %st(0); \
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fstp %st(0); \
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6464:
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/* Likewise, but the argument is nonnegative and not a NaN. */
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#define LDBL_CHECK_FORCE_UFLOW_NONNEG \
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fldt MO(ldbl_min); \
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fld %st(1); \
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fcomip %st(1), %st(0); \
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fstp %st(0); \
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jnc 6464f; \
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fld %st(0); \
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fmul %st(0); \
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fstp %st(0); \
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6464:
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#endif /* x86_64-math-asm.h. */
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