diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 94787b07012b..00803735c41b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2006-11-13  Richard Guenther  <rguenther@suse.de>
+
+	Backport from mainline:
+	2006-10-23  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/21032
+	* convert.c (convert_to_real): Fold (float)-x to -(float)x
+	only if not flag_rounding_math.
+
 2006-11-12  Jason Merrill  <jason@redhat.com>
 	    Andrew Pinski <pinskia@physics.uc.edu>
 
diff --git a/gcc/convert.c b/gcc/convert.c
index 118889fad443..0a9743ac8f84 100644
--- a/gcc/convert.c
+++ b/gcc/convert.c
@@ -248,10 +248,12 @@ convert_to_real (tree type, tree expr)
   if (itype != type && FLOAT_TYPE_P (type))
     switch (TREE_CODE (expr))
       {
-	/* Convert (float)-x into -(float)x.  This is always safe.  */
+	/* Convert (float)-x into -(float)x.  This is safe for
+	   round-to-nearest rounding mode.  */
 	case ABS_EXPR:
 	case NEGATE_EXPR:
-	  if (TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (expr)))
+	  if (!flag_rounding_math
+	      && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (expr)))
 	    return build1 (TREE_CODE (expr), type,
 			   fold (convert_to_real (type,
 						  TREE_OPERAND (expr, 0))));
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 5dbb050612e5..989344ec69d5 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2006-11-13  Richard Guenther  <rguenther@suse.de>
+
+	Backport form mainline:
+	2006-10-23  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/21032
+	* gcc.dg/pr21032.c: New testcase.
+
 2006-11-12 Paul Thomas <pault@gcc.gnu.org>
 
 	PR fortran/29699
diff --git a/gcc/testsuite/gcc.dg/pr21032.c b/gcc/testsuite/gcc.dg/pr21032.c
new file mode 100644
index 000000000000..839a180cead2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr21032.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-optimized -frounding-math" } */
+
+void bar(float x);
+void foo(double x)
+{
+  bar(-x);
+}
+
+/* { dg-final { scan-tree-dump-not "-\\(float\\)" "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */