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[PATCH] fix pr39867, wrong folding to MAX_EXPR
- From: Paolo Bonzini <bonzini at gnu dot org>
- To: gcc-patches at gcc dot gnu dot org
- Date: Fri, 24 Apr 2009 02:40:41 -0400
- Subject: [PATCH] fix pr39867, wrong folding to MAX_EXPR
This is a fix for PR39867, a MAX operation created from a COND_EXPR
with the wrong signedness. The MAX operation must always be created
with the operand type of the comparison, and then possibly casted
to the result type of the COND_EXPR.
Bootstrapped/regtested i686-pc-linux-gnu, ok for trunk and 4.4?
Paolo
2009-04-24 Paolo Bonzini <bonzini@gnu.org>
* fold-const.c (fold_cond_expr_with_comparison): When folding
> and >= to MAX, make sure the MAX uses the same type as the
comparison's operands.
2009-04-24 Paolo Bonzini <bonzini@gnu.org>
* gcc.dg/pr39867.c: New.
Index: fold-const.c
===================================================================
--- fold-const.c (revision 146581)
+++ fold-const.c (working copy)
@@ -5337,31 +5337,34 @@ fold_cond_expr_with_comparison (tree typ
break;
case GT_EXPR:
- /* If C1 is C2 - 1, this is max(A, C2). */
+ /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
+ MAX_EXPR, to preserve the signedness of the comparison. */
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 (MAX_EXPR,
- type,
- fold_convert (type, arg1),
- arg2));
+ return pedantic_non_lvalue (fold_convert (type,
+ fold_build2 (MAX_EXPR, TREE_TYPE (arg00),
+ arg00,
+ fold_convert (TREE_TYPE (arg00),
+ arg2))));
break;
case GE_EXPR:
- /* If C1 is C2 + 1, this is max(A, C2). */
+ /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
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 (MAX_EXPR,
- type,
- fold_convert (type, arg1),
- arg2));
+ return pedantic_non_lvalue (fold_convert (type,
+ fold_build2 (MAX_EXPR, TREE_TYPE (arg00),
+ arg00,
+ fold_convert (TREE_TYPE (arg00),
+ arg2))));
break;
case NE_EXPR:
break;
/* { dg-do link } */
/* { dg-options "-O2" } */
int main (void)
{
int exp = -1;
/* Wrong folding of the LHS to an unsigned MAX leads to 4294967295 >
* 2. */
if (("%u\n", exp < 2 ? 2U : (unsigned int) exp) > 2)
link_error ();
return 0;
}