Module Name: src
Committed By: dsl
Date: Mon Mar 3 08:00:50 UTC 2014
Modified Files:
src/lib/libm/arch/i387: e_acos.S
Log Message:
Drop in a fabs() after the fsqrt().
While it may seem pointless, it the rouding mode is set to round towards
minus infinity then acos(-1) calculates atan2(sqrt(1.0 - 1.0), -1) the subtract
generates -0.0 which sqrt() preserves.
atan2(-0, -1) is -pi, but acos(-1) is expected to be +pi.
This might 'fix' the test failures seen in some environments, but they
are not failing due to an obvously incorrent x87 rounding mode.
To generate a diff of this commit:
cvs rdiff -u -r1.8 -r1.9 src/lib/libm/arch/i387/e_acos.S
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/lib/libm/arch/i387/e_acos.S
diff -u src/lib/libm/arch/i387/e_acos.S:1.8 src/lib/libm/arch/i387/e_acos.S:1.9
--- src/lib/libm/arch/i387/e_acos.S:1.8 Sat Jul 26 19:24:57 2003
+++ src/lib/libm/arch/i387/e_acos.S Mon Mar 3 08:00:50 2014
@@ -7,7 +7,7 @@
#include "abi.h"
-RCSID("$NetBSD: e_acos.S,v 1.8 2003/07/26 19:24:57 salo Exp $")
+RCSID("$NetBSD: e_acos.S,v 1.9 2014/03/03 08:00:50 dsl Exp $")
/* acos = atan (sqrt(1 - x^2) / x) */
ENTRY(__ieee754_acos)
@@ -18,6 +18,7 @@ ENTRY(__ieee754_acos)
fld1
fsubp /* 1 - x^2 */
fsqrt /* sqrt (1 - x^2) */
+ fabs /* Change -0.0 to +0.0 */
fxch %st(1)
fpatan
XMM_DOUBLE_EPILOGUE
