From 1a84c3d6d4bc43c92b6531b09d732e2e9c750dea Mon Sep 17 00:00:00 2001
From: Joseph Myers <joseph@codesourcery.com>
Date: Wed, 14 May 2014 12:38:56 +0000
Subject: Fix log1pl (LDBL_MAX) in FE_UPWARD mode (bug 16564).

Bug 16564 is spurious overflow of log1pl (LDBL_MAX) in FE_UPWARD mode,
resulting from log1pl adding 1 to its argument (for arguments not
close to 0), which overflows in that mode.  This patch fixes this by
avoiding adding 1 to large arguments (precisely what counts as large
depends on the floating-point format).

Tested x86_64 and x86, and spot-checked log1pl tests on mips64 and
powerpc64.

	[BZ #16564]
	* sysdeps/i386/fpu/s_log1pl.S (__log1pl): Do not add 1 to positive
	arguments with exponent 65 or above.
	* sysdeps/ieee754/ldbl-128/s_log1pl.c (__log1pl): Do not add 1 to
	arguments 0x1p113L or above.
	* sysdeps/ieee754/ldbl-128ibm/s_log1pl.c (__log1pl): Do not add 1
	to arguments 0x1p107L or above.
	* sysdeps/x86_64/fpu/s_log1pl.S (__log1pl): Do not add 1 to
	positive arguments with exponent 65 or above.
	* math/auto-libm-test-in: Add more tests of log1p.
	* math/auto-libm-test-out: Regenerated.
---
 sysdeps/i386/fpu/s_log1pl.S            | 7 ++++++-
 sysdeps/ieee754/ldbl-128/s_log1pl.c    | 5 ++++-
 sysdeps/ieee754/ldbl-128ibm/s_log1pl.c | 5 ++++-
 sysdeps/x86_64/fpu/s_log1pl.S          | 7 ++++++-
 4 files changed, 20 insertions(+), 4 deletions(-)

(limited to 'sysdeps')

diff --git a/sysdeps/i386/fpu/s_log1pl.S b/sysdeps/i386/fpu/s_log1pl.S
index 93c07b6..d2d5d3b 100644
--- a/sysdeps/i386/fpu/s_log1pl.S
+++ b/sysdeps/i386/fpu/s_log1pl.S
@@ -53,12 +53,17 @@ ENTRY(__log1pl)
 	sahf
 	jnc	2f
 
+	movzwl	4+8(%esp), %eax
+	xorb	$0x80, %ah
+	cmpl	$0xc040, %eax
+	jae	5f
+
 #ifdef PIC
 	faddl	one@GOTOFF(%edx)
 #else
 	faddl	one
 #endif
-	fyl2x
+5:	fyl2x
 	ret
 
 2:	fyl2xp1
diff --git a/sysdeps/ieee754/ldbl-128/s_log1pl.c b/sysdeps/ieee754/ldbl-128/s_log1pl.c
index d8d89f0..4a30af6 100644
--- a/sysdeps/ieee754/ldbl-128/s_log1pl.c
+++ b/sysdeps/ieee754/ldbl-128/s_log1pl.c
@@ -144,7 +144,10 @@ __log1pl (long double xm1)
 	return xm1;
     }
 
-  x = xm1 + 1.0L;
+  if (xm1 >= 0x1p113L)
+    x = xm1;
+  else
+    x = xm1 + 1.0L;
 
   /* log1p(-1) = -inf */
   if (x <= 0.0L)
diff --git a/sysdeps/ieee754/ldbl-128ibm/s_log1pl.c b/sysdeps/ieee754/ldbl-128ibm/s_log1pl.c
index a346383..e4bb6e8 100644
--- a/sysdeps/ieee754/ldbl-128ibm/s_log1pl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/s_log1pl.c
@@ -140,7 +140,10 @@ __log1pl (long double xm1)
   if (((hx & 0x7fffffff) | lx) == 0)
     return xm1;
 
-  x = xm1 + 1.0L;
+  if (xm1 >= 0x1p107L)
+    x = xm1;
+  else
+    x = xm1 + 1.0L;
 
   /* log1p(-1) = -inf */
   if (x <= 0.0L)
diff --git a/sysdeps/x86_64/fpu/s_log1pl.S b/sysdeps/x86_64/fpu/s_log1pl.S
index b4dbcdf..af3024a 100644
--- a/sysdeps/x86_64/fpu/s_log1pl.S
+++ b/sysdeps/x86_64/fpu/s_log1pl.S
@@ -52,8 +52,13 @@ ENTRY(__log1pl)
 	andb	$1,%ah
 	jz	2f
 
+	movzwl	8+8(%rsp), %eax
+	xorb	$0x80, %ah
+	cmpl	$0xc040, %eax
+	jae	5f
+
 	faddl	MO(one)
-	fyl2x
+5:	fyl2x
 	ret
 
 2:	fyl2xp1
-- 
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