From e5123d087ed24066c03c97c92a15d255c8d318dd Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <thomas@codesourcery.com>
Date: Mon, 6 May 2013 10:23:02 +0200
Subject: [PATCH] fp-bit.c (unpack_d, pack_d): Properly preserve and restore a
 NaN's payload.

libgcc/
	* fp-bit.c (unpack_d, pack_d): Properly preserve and restore a
	NaN's payload.

From-SVN: r198622
---
 libgcc/ChangeLog |  3 +++
 libgcc/fp-bit.c  | 15 ++++++++++++---
 libgcc/fp-bit.h  |  2 +-
 3 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/libgcc/ChangeLog b/libgcc/ChangeLog
index e4e0d570050..c874a84b6b0 100644
--- a/libgcc/ChangeLog
+++ b/libgcc/ChangeLog
@@ -1,5 +1,8 @@
 2013-05-06  Thomas Schwinge  <thomas@codesourcery.com>
 
+	* fp-bit.c (unpack_d, pack_d): Properly preserve and restore a
+	NaN's payload.
+
 	* fp-bit.h [FLOAT] (QUIET_NAN): Correct value.
 
 2013-04-25  Alan Modra  <amodra@gmail.com>
diff --git a/libgcc/fp-bit.c b/libgcc/fp-bit.c
index 60f23387e81..9b0c194604f 100644
--- a/libgcc/fp-bit.c
+++ b/libgcc/fp-bit.c
@@ -213,11 +213,18 @@ pack_d (const fp_number_type *src)
   else if (isnan (src))
     {
       exp = EXPMAX;
+      /* Restore the NaN's payload.  */
+      fraction >>= NGARDS;
+      fraction &= QUIET_NAN - 1;
       if (src->class == CLASS_QNAN || 1)
 	{
 #ifdef QUIET_NAN_NEGATED
-	  fraction |= QUIET_NAN - 1;
+	  /* The quiet/signaling bit remains unset.  */
+	  /* Make sure the fraction has a non-zero value.  */
+	  if (fraction == 0)
+	    fraction |= QUIET_NAN - 1;
 #else
+	  /* Set the quiet/signaling bit.  */
 	  fraction |= QUIET_NAN;
 #endif
 	}
@@ -573,8 +580,10 @@ unpack_d (FLO_union_type * src, fp_number_type * dst)
 	    {
 	      dst->class = CLASS_SNAN;
 	    }
-	  /* Keep the fraction part as the nan number */
-	  dst->fraction.ll = fraction;
+	  /* Now that we know which kind of NaN we got, discard the
+	     quiet/signaling bit, but do preserve the NaN payload.  */
+	  fraction &= ~QUIET_NAN;
+	  dst->fraction.ll = fraction << NGARDS;
 	}
     }
   else
diff --git a/libgcc/fp-bit.h b/libgcc/fp-bit.h
index 2ac504a56e5..b6fe9f7a288 100644
--- a/libgcc/fp-bit.h
+++ b/libgcc/fp-bit.h
@@ -297,7 +297,7 @@ typedef unsigned int UTItype __attribute__ ((mode (TI)));
 /* numeric parameters */
 /* F_D_BITOFF is the number of bits offset between the MSB of the mantissa
    of a float and of a double. Assumes there are only two float types.
-   (double::FRAC_BITS+double::NGARDS-(float::FRAC_BITS-float::NGARDS))
+   (double::FRAC_BITS+double::NGARDS-(float::FRAC_BITS+float::NGARDS))
  */
 #define F_D_BITOFF (52+8-(23+7))