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No need for boundary case handling in x86-32 __ieee_log

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This commit is contained in:
Ulrich Drepper 2011-10-15 22:21:53 -04:00
parent d4a285692a
commit 79b195b55a
2 changed files with 4 additions and 52 deletions
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3
ChangeLog
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@ -1,5 +1,8 @@
2011-10-15 Ulrich Drepper <drepper@gmail.com>
* sysdeps/i386/i686/fpu/e_log.S: No need for the fyl2xp1 use, fyl2x
is sufficient, at least on modern CPUs.
* sysdeps/ieee754/dbl-64/wordsize-64/s_floor.c: New file.
* sysdeps/ieee754/dbl-64/e_cosh.c: Cleanup.

53
sysdeps/i386/i686/fpu/e_log.S
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@ -2,34 +2,11 @@
* Written by J.T. Conklin <jtc@netbsd.org>.
* Public domain.
*
* Changed to use fyl2xp1 for values near 1, <drepper@cygnus.com>.
* Adapted for i686 instructions.
*/
#include <machine/asm.h>
#ifdef __ELF__
.section .rodata.cst8,"aM",@progbits,8
#else
.text
#endif
.p2align 3
ASM_TYPE_DIRECTIVE(one,@object)
one: .double 1.0
ASM_SIZE_DIRECTIVE(one)
/* It is not important that this constant is precise. It is only
a value which is known to be on the safe side for using the
fyl2xp1 instruction. */
ASM_TYPE_DIRECTIVE(limit,@object)
limit: .double 0.29
ASM_SIZE_DIRECTIVE(limit)
#ifdef PIC
# define MO(op) op##@GOTOFF(%edx)
#else
# define MO(op) op
#endif
.text
ENTRY(__ieee754_log)
@ -37,22 +14,6 @@ ENTRY(__ieee754_log)
fldl 4(%esp) // x : log(2)
fucomi %st
jp 3f
#ifdef PIC
LOAD_PIC_REG (dx)
#endif
fld %st // x : x : log(2)
fsubl MO(one) // x-1 : x : log(2)
fld %st // x-1 : x-1 : x : log(2)
fabs // |x-1| : x-1 : x : log(2)
fld MO(limit) // 0.29 : |x-1| : x-1 : x : log(2)
fcomip %st(1) // |x-1| : x-1 : x : log(2)
fstp %st(0) // x-1 : x : log(2)
jc 2f
fstp %st(1) // x-1 : log(2)
fyl2xp1 // log(x)
ret
2: fstp %st(0) // x : log(2)
fyl2x // log(x)
ret
@ -63,18 +24,6 @@ END (__ieee754_log)
ENTRY(__log_finite)
fldln2 // log(2)
fldl 4(%esp) // x : log(2)
#ifdef PIC
LOAD_PIC_REG (dx)
#endif
fld %st // x : x : log(2)
fsubl MO(one) // x-1 : x : log(2)
fld %st // x-1 : x-1 : x : log(2)
fabs // |x-1| : x-1 : x : log(2)
fld MO(limit) // 0.29 : |x-1| : x-1 : x : log(2)
fcomip %st(1) // |x-1| : x-1 : x : log(2)
fstp %st(0) // x-1 : x : log(2)
jc 2b
fstp %st(1) // x-1 : log(2)
fyl2xp1 // log(x)
fyl2x // log(x)
ret
END(__log_finite)