[PATCH v2] x86-64: Replace `and %ah` write with `test %ah` read

[Noah Goldstein]

High8 partial registers can incur a stall when being modified (if not
renamed seperately), or at the very least incur extra backend uops (if
renamed seperately). Either way read only `testl $0x4, %ah` is preferable
to `andb $0x4, %ah`.

Function size is unchanged when accounting for 16-byte padding.
---
 sysdeps/x86_64/fpu/e_fmodl.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sysdeps/x86_64/fpu/e_fmodl.S b/sysdeps/x86_64/fpu/e_fmodl.S
index d754668bce..e9a76178f9 100644
--- a/sysdeps/x86_64/fpu/e_fmodl.S
+++ b/sysdeps/x86_64/fpu/e_fmodl.S
@@ -13,7 +13,7 @@ ENTRY(__ieee754_fmodl)
 	fldt	8(%rsp)
 1:	fprem
 	fstsw	%ax
-	and	$04,%ah
+	testb	$0x4,%ah
 	jnz	1b
 	fstp	%st(1)
 	ret
-- 
2.34.1