re PR rtl-optimization/31691 (optimized code taking the wrong branch)

	PR rtl-optimization/31691
	* combine.c (simplify_set): Build a new src pattern instead of
	substituting its operands in the COMPARE case.

From-SVN: r124797

gcc/ChangeLog

+2007-05-17  Eric Botcazou  <ebotcazou@libertysurf.fr>
+
+	PR rtl-optimization/31691
+	* combine.c (simplify_set): Build a new src pattern instead of
+	substituting its operands in the COMPARE case.
+
 2007-05-17  Zdenek Dvorak  <dvorakz@suse.cz>
 
 	* tree-vrp.c (finalize_jump_threads): Do not care about dominance info.

gcc/combine.c

@@ -5343,14 +5343,14 @@ simplify_set (rtx x)
 	}
       else if (GET_MODE (op0) == compare_mode && op1 == const0_rtx)
 	{
-	  SUBST(SET_SRC (x), op0);
+	  SUBST (SET_SRC (x), op0);
 	  src = SET_SRC (x);
 	}
-      else
+      /* Otherwise, update the COMPARE if needed.  */
+      else if (XEXP (src, 0) != op0 || XEXP (src, 1) != op1)
 	{
-	  /* Otherwise, update the COMPARE if needed.  */
-	  SUBST (XEXP (src, 0), op0);
-	  SUBST (XEXP (src, 1), op1);
+	  SUBST (SET_SRC (x), gen_rtx_COMPARE (compare_mode, op0, op1));
+	  src = SET_SRC (x);
 	}
     }
   else

gcc/testsuite/ChangeLog

+2007-05-17  Eric Botcazou  <ebotcazou@libertysurf.fr>
+
+	* gcc.c-torture/execute/20070517-1.c: New test.
+
 2007-05-17  Daniel Franke <franke.daniel@gmail.com>
 
 	PR fortran/31919

gcc/testsuite/gcc.c-torture/execute/20070517-1.c

+/* PR rtl-optimization/31691 */
+/* Origin: Chi-Hua Chen <stephaniechc-gccbug@yahoo.com> */
+
+extern void abort (void);
+
+static int get_kind(int) __attribute__ ((noinline));
+
+static int get_kind(int v)
+{
+  volatile int k = v;
+  return k;
+}
+
+static int some_call(void) __attribute__ ((noinline));
+
+static int some_call(void)
+{
+  return 0;
+}
+
+static void example (int arg)
+{
+  int tmp, kind = get_kind (arg);
+
+  if (kind == 9 || kind == 10 || kind == 5)
+    {
+      if (some_call() == 0)
+        {
+          if (kind == 9 || kind == 10)
+            tmp = arg;
+          else
+            abort();
+        }
+    }
+} 
+
+int main(void)
+{
+  example(10);
+  return 0;
+}