From 316e024f63af0d0d2bb0df3dfce2620f4be827d1 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Sat, 17 Mar 2012 19:29:00 -0400 Subject: optimize x86 feclearexcept if all exception flags will be cleared, we can avoid the expensive store/reload of the environment and just use the fnclex instruction. --- src/fenv/i386/fenv.s | 36 ++++++++++++++++++++---------------- 1 file changed, 20 insertions(+), 16 deletions(-) (limited to 'src') diff --git a/src/fenv/i386/fenv.s b/src/fenv/i386/fenv.s index 647b7961..e365b8f4 100644 --- a/src/fenv/i386/fenv.s +++ b/src/fenv/i386/fenv.s @@ -1,30 +1,34 @@ -2: not %ecx +.global feclearexcept +.type feclearexcept,@function +feclearexcept: + mov 4(%esp),%ecx + not %ecx + test $0x3f,%ecx + jnz 2f +1: fnclex + xor %eax,%eax + ret +2: fnstsw %ax + and %ecx,%eax + jz 1b sub $32,%esp fnstenv (%esp) - and %ecx,4(%esp) - or %edx,4(%esp) + mov %al,4(%esp) fldenv (%esp) add $32,%esp - ret - -.global feclearexcept -.type feclearexcept,@function -feclearexcept: xor %eax,%eax - mov 4(%esp),%ecx - xor %edx,%edx - test %ecx,%ecx - jnz 2b ret .global feraiseexcept .type feraiseexcept,@function feraiseexcept: + mov 4(%esp),%eax + sub $32,%esp + fnstenv (%esp) + or %al,4(%esp) + fldenv (%esp) + add $32,%esp xor %eax,%eax - mov 4(%esp),%edx - xor %ecx,%ecx - test %edx,%edx - jnz 2b ret .global fesetround -- cgit v1.2.1