re PR tree-optimization/34099 (optimizer problem)

2007-11-19  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/34099
	* tree-ssa-ccp.c (likely_value): Exclude all but PLUS_EXPR,
	MINUS_EXPR and POINTER_PLUS_EXPR from handling as UNDEFINED
	if only one operand is undefined.

	* gcc.c-torture/execute/pr34099-2.c: New testcase.

From-SVN: r130289

gcc/ChangeLog

+2007-11-19  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/34099
+	* tree-ssa-ccp.c (likely_value): Exclude all but PLUS_EXPR,
+	MINUS_EXPR and POINTER_PLUS_EXPR from handling as UNDEFINED
+	if only one operand is undefined.
+
 2007-11-19  Eric Botcazou  <ebotcazou@libertysurf.fr>
 
 	PR tree-optimization/34036

gcc/testsuite/gcc.c-torture/execute/pr34099-2.c

+int test1 (int b, int c)
+{
+  char x;
+  if (b)
+    return x / c;
+  else
+    return 1;
+}
+int test2 (int b, int c)
+{
+  int x;
+  if (b)
+    return x * c;
+  else
+    return 1;
+}
+int test3 (int b, int c)
+{
+  int x;
+  if (b)
+    return x % c;
+  else
+    return 1;
+}
+int test4 (int b, int c)
+{
+  char x;
+  if (b)
+    return x == c;
+  else
+    return 1;
+}
+
+extern void abort (void);
+int main()
+{
+  if (test1(1, 1000) != 0)
+    abort ();
+  if (test2(1, 0) != 0)
+    abort ();
+  if (test3(1, 1) != 0)
+    abort ();
+  if (test4(1, 1000) != 0)
+    abort ();
+  return 0;
+}
+

gcc/tree-ssa-ccp.c

@@ -582,32 +582,13 @@ likely_value (tree stmt)
 	/* Unary operators are handled with all_undefined_operands.  */
 	case PLUS_EXPR:
 	case MINUS_EXPR:
-	case MULT_EXPR:
 	case POINTER_PLUS_EXPR:
-	case TRUNC_DIV_EXPR:
-	case CEIL_DIV_EXPR:
-	case FLOOR_DIV_EXPR:
-	case ROUND_DIV_EXPR:
-	case TRUNC_MOD_EXPR:
-	case CEIL_MOD_EXPR:
-	case FLOOR_MOD_EXPR:
-	case ROUND_MOD_EXPR:
-	case RDIV_EXPR:
-	case EXACT_DIV_EXPR:
-	case LSHIFT_EXPR:
-	case RSHIFT_EXPR:
-	case LROTATE_EXPR:
-	case RROTATE_EXPR:
-	case EQ_EXPR:
-	case NE_EXPR:
-	case LT_EXPR:
-	case GT_EXPR:
 	  /* Not MIN_EXPR, MAX_EXPR.  One VARYING operand may be selected.
 	     Not bitwise operators, one VARYING operand may specify the
 	     result completely.  Not logical operators for the same reason.
-	     Not LE/GE comparisons or unordered comparisons.  Not
-	     COMPLEX_EXPR as one VARYING operand makes the result partly
-	     not UNDEFINED.  */
+	     Not COMPLEX_EXPR as one VARYING operand makes the result partly
+	     not UNDEFINED.  Not *DIV_EXPR, comparisons and shifts because
+	     the undefined operand may be promoted.  */
 	  return UNDEFINED;
 
 	default: