[PATCH] Fix fold_cond_expr_with_comparison (PR middle-end/40747)

[Jakub Jelinek]

Hi!

This is something Paolo Bonzini fixed already for > and >= to MAX
optimization, but is needed for MIN as well.  Since Richard's
http://gcc.gnu.org/ml/gcc-patches/2008-04/msg01303.html
change operand_equal_p ignores signedness and precision for INTEGER_CSTs,
so we need to make sure MIN_EXPR is done in the right type.
For MAX_EXPR the patch just cleans up formatting.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk/4.4?

2009-07-14  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/40747
	* fold-const.c (fold_cond_expr_with_comparison): When folding
	< and <= to MIN, make sure the MIN uses the same type as the
	comparison's operands.

	* gcc.c-torture/execute/pr40747.c: New test.

--- gcc/fold-const.c.jj	2009-07-09 08:10:38.000000000 +0200
+++ gcc/fold-const.c	2009-07-14 20:39:46.000000000 +0200
@@ -5310,31 +5310,35 @@ fold_cond_expr_with_comparison (tree typ
 	return fold_build3 (COND_EXPR, type, arg0, arg1, arg2);
 
       case LT_EXPR:
-	/* If C1 is C2 + 1, this is min(A, C2).  */
+	/* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
+	   MIN_EXPR, to preserve the signedness of the comparison.  */
 	if (! operand_equal_p (arg2, TYPE_MAX_VALUE (type),
 			       OEP_ONLY_CONST)
 	    && operand_equal_p (arg01,
 				const_binop (PLUS_EXPR, arg2,
 					     build_int_cst (type, 1), 0),
 				OEP_ONLY_CONST))
-	  return pedantic_non_lvalue (fold_build2 (MIN_EXPR,
-						   type,
-						   fold_convert (type, arg1),
-						   arg2));
+	  {
+	    tem = fold_build2 (MIN_EXPR, TREE_TYPE (arg00), arg00,
+			       fold_convert (TREE_TYPE (arg00), arg2));
+	    return pedantic_non_lvalue (fold_convert (type, tem));
+	  }
 	break;
 
       case LE_EXPR:
-	/* If C1 is C2 - 1, this is min(A, C2).  */
+	/* If C1 is C2 - 1, this is min(A, C2), with the same care
+	   as above.  */
 	if (! operand_equal_p (arg2, TYPE_MIN_VALUE (type),
 			       OEP_ONLY_CONST)
 	    && operand_equal_p (arg01,
 				const_binop (MINUS_EXPR, arg2,
 					     build_int_cst (type, 1), 0),
 				OEP_ONLY_CONST))
-	  return pedantic_non_lvalue (fold_build2 (MIN_EXPR,
-						   type,
-						   fold_convert (type, arg1),
-						   arg2));
+	  {
+	    tem = fold_build2 (MIN_EXPR, TREE_TYPE (arg00), arg00,
+			       fold_convert (TREE_TYPE (arg00), arg2));
+	    return pedantic_non_lvalue (fold_convert (type, tem));
+	  }
 	break;
 
       case GT_EXPR:
@@ -5346,11 +5350,11 @@ fold_cond_expr_with_comparison (tree typ
 				const_binop (MINUS_EXPR, arg2,
 					     build_int_cst (type, 1), 0),
 				OEP_ONLY_CONST))
-	  return pedantic_non_lvalue (fold_convert (type,
-				      fold_build2 (MAX_EXPR, TREE_TYPE (arg00),
-						   arg00,
-						   fold_convert (TREE_TYPE (arg00),
-							         arg2))));
+	  {
+	    tem = fold_build2 (MAX_EXPR, TREE_TYPE (arg00), arg00,
+			       fold_convert (TREE_TYPE (arg00), arg2));
+	    return pedantic_non_lvalue (fold_convert (type, tem));
+	  }
 	break;
 
       case GE_EXPR:
@@ -5361,11 +5365,11 @@ fold_cond_expr_with_comparison (tree typ
 				const_binop (PLUS_EXPR, arg2,
 					     build_int_cst (type, 1), 0),
 				OEP_ONLY_CONST))
-	  return pedantic_non_lvalue (fold_convert (type,
-				      fold_build2 (MAX_EXPR, TREE_TYPE (arg00),
-						   arg00,
-						   fold_convert (TREE_TYPE (arg00),
-							         arg2))));
+	  {
+	    tem = fold_build2 (MAX_EXPR, TREE_TYPE (arg00), arg00,
+			       fold_convert (TREE_TYPE (arg00), arg2));
+	    return pedantic_non_lvalue (fold_convert (type, tem));
+	  }
 	break;
       case NE_EXPR:
 	break;
--- gcc/testsuite/gcc.c-torture/execute/pr40747.c.jj	2009-07-14 20:49:14.000000000 +0200
+++ gcc/testsuite/gcc.c-torture/execute/pr40747.c	2009-07-14 20:48:55.000000000 +0200
@@ -0,0 +1,22 @@
+/* PR middle-end/40747 */
+
+extern void abort (void);
+
+int
+foo (int i)
+{
+  return (i < 4 && i >= 0) ? i : 4;
+}
+
+int
+main ()
+{
+  if (foo (-1) != 4) abort ();
+  if (foo (0) != 0) abort ();
+  if (foo (1) != 1) abort ();
+  if (foo (2) != 2) abort ();
+  if (foo (3) != 3) abort ();
+  if (foo (4) != 4) abort ();
+  if (foo (5) != 4) abort ();
+  return 0;
+}

	Jakub