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authorJoseph Myers <joseph@codesourcery.com>2013-11-29 16:31:16 +0000
committerJoseph Myers <joseph@codesourcery.com>2013-11-29 16:31:16 +0000
commitea3bc4e821e20e70b093c9a33e54f99c79e0d847 (patch)
tree822fa8b196e69580a4f4c9fb4eb63bd0ddbe6147 /sysdeps/i386
parent0712c9d861f4e861313a7f9fad06609bd1afb263 (diff)
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Fix x86 sqrt rounding (bug 14032).
Diffstat (limited to 'sysdeps/i386')
-rw-r--r--sysdeps/i386/fpu/e_sqrt.S10
-rw-r--r--sysdeps/i386/fpu/w_sqrt.c8
2 files changed, 18 insertions, 0 deletions
diff --git a/sysdeps/i386/fpu/e_sqrt.S b/sysdeps/i386/fpu/e_sqrt.S
index 1054ba4532..fba5833a9a 100644
--- a/sysdeps/i386/fpu/e_sqrt.S
+++ b/sysdeps/i386/fpu/e_sqrt.S
@@ -7,7 +7,17 @@
 
 ENTRY(__ieee754_sqrt)
 	fldl	4(%esp)
+	subl	$8, %esp
+	cfi_adjust_cfa_offset (8)
+	fstcw	4(%esp)
+	movl	$0xfeff, %edx
+	andl	4(%esp), %edx
+	movl	%edx, (%esp)
+	fldcw	(%esp)
 	fsqrt
+	fldcw	4(%esp)
+	addl	$8, %esp
+	cfi_adjust_cfa_offset (-8)
 	ret
 END (__ieee754_sqrt)
 strong_alias (__ieee754_sqrt, __sqrt_finite)
diff --git a/sysdeps/i386/fpu/w_sqrt.c b/sysdeps/i386/fpu/w_sqrt.c
new file mode 100644
index 0000000000..19b5074179
--- /dev/null
+++ b/sysdeps/i386/fpu/w_sqrt.c
@@ -0,0 +1,8 @@
+/* The inline __ieee754_sqrt is not correctly rounding; it's OK for
+   most internal uses in glibc, but not for sqrt itself.  */
+#define __ieee754_sqrt __avoid_ieee754_sqrt
+#include <math.h>
+#include <math_private.h>
+#undef __ieee754_sqrt
+extern double __ieee754_sqrt (double);
+#include <math/w_sqrt.c>