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Fix i386/x86_64 log* (1) zero sign for -ffinite-math-only (bug 19213) [committed]
- From: Joseph Myers <joseph at codesourcery dot com>
- To: <libc-alpha at sourceware dot org>
- Date: Thu, 5 Nov 2015 21:57:26 +0000
- Subject: Fix i386/x86_64 log* (1) zero sign for -ffinite-math-only (bug 19213) [committed]
- Authentication-results: sourceware.org; auth=none
For the -ffinite-math-only versions of various x86_64 and x86 log*
functions, a zero result from log* (1) is returned with incorrect sign
in round-downward mode. This patch fixes this in a similar way to the
previous fixes for the non-*_finite versions of the functions.
Tested for x86_64 and x86 (including an i586 build), together with a
patch that will be applied separately to enable the main libm-test.inc
tests for the finite-math-only functions. Committed.
2015-11-05 Joseph Myers <joseph@codesourcery.com>
[BZ #19213]
* sysdeps/i386/fpu/e_log.S (__log_finite): Ensure +0 is always
returned for argument 1.
* sysdeps/i386/fpu/e_logf.S (__logf_finite): Likewise.
* sysdeps/i386/fpu/e_logl.S (__logl_finite): Likewise.
* sysdeps/i386/i686/fpu/e_logl.S (__logl_finite): Likewise.
* sysdeps/x86_64/fpu/e_log10l.S (__log10l_finite): Likewise.
* sysdeps/x86_64/fpu/e_log2l.S (__log2l_finite): Likewise.
* sysdeps/x86_64/fpu/e_logl.S (__logl_finite): Likewise.
diff --git a/sysdeps/i386/fpu/e_log.S b/sysdeps/i386/fpu/e_log.S
index 3fa32aa..335df22 100644
--- a/sysdeps/i386/fpu/e_log.S
+++ b/sysdeps/i386/fpu/e_log.S
@@ -80,7 +80,13 @@ ENTRY(__log_finite)
fnstsw // x-1 : x : log(2)
andb $0x45, %ah
jz 2b
- fstp %st(1) // x-1 : log(2)
+ fxam
+ fnstsw
+ andb $0x45, %ah
+ cmpb $0x40, %ah
+ jne 6f
+ fabs // log(1) is +0 in all rounding modes.
+6: fstp %st(1) // x-1 : log(2)
fyl2xp1 // log(x)
ret
END(__log_finite)
diff --git a/sysdeps/i386/fpu/e_logf.S b/sysdeps/i386/fpu/e_logf.S
index ca83d39..de967a3 100644
--- a/sysdeps/i386/fpu/e_logf.S
+++ b/sysdeps/i386/fpu/e_logf.S
@@ -81,7 +81,13 @@ ENTRY(__logf_finite)
fnstsw // x-1 : x : log(2)
andb $0x45, %ah
jz 2b
- fstp %st(1) // x-1 : log(2)
+ fxam
+ fnstsw
+ andb $0x45, %ah
+ cmpb $0x40, %ah
+ jne 6f
+ fabs // log(1) is +0 in all rounding modes.
+6: fstp %st(1) // x-1 : log(2)
fyl2xp1 // log(x)
ret
END(__logf_finite)
diff --git a/sysdeps/i386/fpu/e_logl.S b/sysdeps/i386/fpu/e_logl.S
index 828e98a..7a6d370 100644
--- a/sysdeps/i386/fpu/e_logl.S
+++ b/sysdeps/i386/fpu/e_logl.S
@@ -84,7 +84,13 @@ ENTRY(__logl_finite)
fnstsw // x-1 : x : log(2)
andb $0x45, %ah
jz 2b
- fstp %st(1) // x-1 : log(2)
+ fxam
+ fnstsw
+ andb $0x45, %ah
+ cmpb $0x40, %ah
+ jne 7f
+ fabs // log(1) is +0 in all rounding modes.
+7: fstp %st(1) // x-1 : log(2)
fyl2xp1 // log(x)
ret
END(__logl_finite)
diff --git a/sysdeps/i386/i686/fpu/e_logl.S b/sysdeps/i386/i686/fpu/e_logl.S
index 0ccc8fc..e9ecbcd 100644
--- a/sysdeps/i386/i686/fpu/e_logl.S
+++ b/sysdeps/i386/i686/fpu/e_logl.S
@@ -81,7 +81,13 @@ ENTRY(__logl_finite)
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)
+ fxam
+ fnstsw
+ andb $0x45, %ah
+ cmpb $0x40, %ah
+ jne 6f
+ fabs // log(1) is +0 in all rounding modes.
+6: fstp %st(1) // x-1 : log(2)
fyl2xp1 // log(x)
ret
END(__logl_finite)
diff --git a/sysdeps/x86_64/fpu/e_log10l.S b/sysdeps/x86_64/fpu/e_log10l.S
index 2607ad1..8fa6164 100644
--- a/sysdeps/x86_64/fpu/e_log10l.S
+++ b/sysdeps/x86_64/fpu/e_log10l.S
@@ -79,7 +79,13 @@ ENTRY(__log10l_finite)
fnstsw // x-1 : x : log10(2)
andb $0x45, %ah
jz 2b
- fstp %st(1) // x-1 : log10(2)
+ fxam
+ fnstsw
+ andb $0x45, %ah
+ cmpb $0x40, %ah
+ jne 6f
+ fabs // log10(1) is +0 in all rounding modes.
+6: fstp %st(1) // x-1 : log10(2)
fyl2xp1 // log10(x)
ret
END(__log10l_finite)
diff --git a/sysdeps/x86_64/fpu/e_log2l.S b/sysdeps/x86_64/fpu/e_log2l.S
index c12906d..a063255 100644
--- a/sysdeps/x86_64/fpu/e_log2l.S
+++ b/sysdeps/x86_64/fpu/e_log2l.S
@@ -78,7 +78,13 @@ ENTRY(__log2l_finite)
fnstsw // x-1 : x : 1
andb $0x45, %ah
jz 2b
- fstp %st(1) // x-1 : 1
+ fxam
+ fnstsw
+ andb $0x45, %ah
+ cmpb $0x40, %ah
+ jne 6f
+ fabs // log2(1) is +0 in all rounding modes.
+6: fstp %st(1) // x-1 : 1
fyl2xp1 // log(x)
ret
END (__log2l_finite)
diff --git a/sysdeps/x86_64/fpu/e_logl.S b/sysdeps/x86_64/fpu/e_logl.S
index 047b8db..dbe6fd5 100644
--- a/sysdeps/x86_64/fpu/e_logl.S
+++ b/sysdeps/x86_64/fpu/e_logl.S
@@ -81,7 +81,13 @@ ENTRY(__logl_finite)
fnstsw // x-1 : x : log(2)
andb $0x45, %ah
jz 2b
- fstp %st(1) // x-1 : log(2)
+ fxam
+ fnstsw
+ andb $0x45, %ah
+ cmpb $0x40, %ah
+ jne 7f
+ fabs // log(1) is +0 in all rounding modes.
+7: fstp %st(1) // x-1 : log(2)
fyl2xp1 // log(x)
ret
END (__logl_finite)
--
Joseph S. Myers
joseph@codesourcery.com