re PR target/22077 (vec_all_eq does not produce good result)

PR 22077.
Oked by Roger Sayle.

From-SVN: r101211

gcc/ChangeLog

+2005-06-20  Roger Sayle  <roger@eyesopen.com>
+2005-06-20  Fariborz Jahanian <fjahanian@apple.com>
+
+	* combine.c (simplify_set): Simplify setting of CC register
+	by removing redundant compare with 0 on RHS.
+
 2005-06-20  Jan Beulich  <jbeulich@novell.com>
 
 	* config/i386/netware-libgcc.def: Update copyright.

gcc/combine.c

@@ -5274,6 +5274,11 @@ simplify_set (rtx x)
 	  SUBST (SET_SRC (x), gen_rtx_COMPARE (compare_mode, op0, op1));
 	  src = SET_SRC (x);
 	}
+      else if (GET_MODE (op0) == compare_mode && op1 == const0_rtx)
+	{
+	  SUBST(SET_SRC (x), op0);
+	  src = SET_SRC (x);
+        }
       else
 	{
 	  /* Otherwise, update the COMPARE if needed.  */

gcc/testsuite/gcc.dg/altivec-nomfcr.c

+/* { dg-do compile { target powerpc-*-* } } */
+/* { dg-options "-O3 -maltivec" } */
+/* { dg-final { scan-assembler-not "mfcr" } } */
+
+#include <altivec.h>
+
+int foo(vector float x, vector float y) {
+        if (vec_all_eq(x,y)) return 3245;
+        else return 12;
+}