From 40244be3729149ff440caf18e445ec17b0d0b511 Mon Sep 17 00:00:00 2001
From: Joseph Myers <joseph@codesourcery.com>
Date: Thu, 23 Jun 2016 22:17:41 +0000
Subject: Fix i386/x86_64 scalbl with sNaN input (bug 20296).

The x86_64 and i386 versions of scalbl return sNaN for some cases of
sNaN input and are missing "invalid" exceptions for other cases.  This
results from overly complicated code that either returns a NaN input,
or discards both inputs when one is NaN and loads a NaN from memory.
This patch fixes this by simplifying the code to add the arguments
when either one is NaN.

Tested for x86_64 and x86.

	[BZ #20296]
	* sysdeps/i386/fpu/e_scalbl.S (__ieee754_scalbl): Add arguments
	when either argument is a NaN.
	* sysdeps/x86_64/fpu/e_scalbl.S (__ieee754_scalbl): Likewise.
	* math/libm-test.inc (scalb_test_data): Add sNaN tests.
---
 sysdeps/i386/fpu/e_scalbl.S   | 16 +++-------------
 sysdeps/x86_64/fpu/e_scalbl.S | 13 +++----------
 2 files changed, 6 insertions(+), 23 deletions(-)

(limited to 'sysdeps')

diff --git a/sysdeps/i386/fpu/e_scalbl.S b/sysdeps/i386/fpu/e_scalbl.S
index d10b22ea83..896f599cb0 100644
--- a/sysdeps/i386/fpu/e_scalbl.S
+++ b/sysdeps/i386/fpu/e_scalbl.S
@@ -45,7 +45,7 @@ ENTRY(__ieee754_scalbl)
 	fnstsw
 	andl	$0x4500, %eax
 	cmpl	$0x0100, %eax
-	je	3f
+	je	2f
 	fld	%st(1)
 	frndint
 	fcomp	%st(2)
@@ -76,18 +76,8 @@ ENTRY(__ieee754_scalbl)
 	fldl	MOX(zero_nan, %eax, 1)
 	ret
 
-	/* The result is NaN, but we must not raise an exception.
-	   So use a variable.  */
-2:	fstp	%st
-	fstp	%st
-#ifdef  PIC
-	LOAD_PIC_REG (cx)
-#endif
-	fldl	MO(nan)
-	ret
-
-	/* The first parameter is a NaN.  Return it.  */
-3:	fstp	%st(1)
+	/* The result is NaN; raise an exception for sNaN arguments.  */
+2:	faddp
 	ret
 
 	/* Return NaN and raise the invalid exception.  */
diff --git a/sysdeps/x86_64/fpu/e_scalbl.S b/sysdeps/x86_64/fpu/e_scalbl.S
index 331bee580c..2982dc3b9e 100644
--- a/sysdeps/x86_64/fpu/e_scalbl.S
+++ b/sysdeps/x86_64/fpu/e_scalbl.S
@@ -44,7 +44,7 @@ ENTRY(__ieee754_scalbl)
 	fnstsw
 	andl	$0x4500, %eax
 	cmpl	$0x0100, %eax
-	je	3f
+	je	2f
 	fld	%st(1)
 	frndint
 	fcomip	%st(2), %st
@@ -75,15 +75,8 @@ ENTRY(__ieee754_scalbl)
 #endif
 	ret
 
-	/* The result is NaN, but we must not raise an exception.
-	   So use a variable.  */
-2:	fstp	%st
-	fstp	%st
-	fldl	MO(nan)
-	ret
-
-	/* The first parameter is a NaN.  Return it.  */
-3:	fstp	%st(1)
+	/* The result is NaN; raise an exception for sNaN arguments.  */
+2:	faddp
 	ret
 
 	/* Return NaN and raise the invalid exception.  */
-- 
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