Commit 684f84de by Marek Polacek Committed by Marek Polacek

re PR c/80525 (-Wlogical-op confused by undefined integer overflow)

	PR c/80525
	* c-warn.c (unwrap_c_maybe_const): New.
	(warn_logical_operator): Call it.

	* c-c++-common/Wlogical-op-1.c: Don't use -fwrapv anymore.
	* c-c++-common/Wlogical-op-2.c: New test.

From-SVN: r247786
parent 641da50a
2017-05-09 Marek Polacek <polacek@redhat.com>
PR c/80525
* c-warn.c (unwrap_c_maybe_const): New.
(warn_logical_operator): Call it.
2017-05-09 Nathan Sidwell <nathan@acm.org>
* c-common.c (c_register_builtin_type): Use pushdecl lang_hook.
......
......@@ -30,6 +30,7 @@ along with GCC; see the file COPYING3. If not see
#include "intl.h"
#include "asan.h"
#include "gcc-rich-location.h"
#include "gimplify.h"
/* Print a warning if a constant expression had overflow in folding.
Invoke this function on every expression that the language
......@@ -112,6 +113,21 @@ overflow_warning (location_t loc, tree value)
}
}
/* Helper function for walk_tree. Unwrap C_MAYBE_CONST_EXPRs in an expression
pointed to by TP. */
static tree
unwrap_c_maybe_const (tree *tp, int *walk_subtrees, void *)
{
if (TREE_CODE (*tp) == C_MAYBE_CONST_EXPR)
{
*tp = C_MAYBE_CONST_EXPR_EXPR (*tp);
/* C_MAYBE_CONST_EXPRs don't nest. */
*walk_subtrees = false;
}
return NULL_TREE;
}
/* Warn about uses of logical || / && operator in a context where it
is likely that the bitwise equivalent was intended by the
programmer. We have seen an expression in which CODE is a binary
......@@ -189,11 +205,11 @@ warn_logical_operator (location_t location, enum tree_code code, tree type,
(with OR) or trivially false (with AND). If so, do not warn.
This is a common idiom for testing ranges of data types in
portable code. */
op_left = unshare_expr (op_left);
walk_tree_without_duplicates (&op_left, unwrap_c_maybe_const, NULL);
lhs = make_range (op_left, &in0_p, &low0, &high0, &strict_overflow_p);
if (!lhs)
return;
if (TREE_CODE (lhs) == C_MAYBE_CONST_EXPR)
lhs = C_MAYBE_CONST_EXPR_EXPR (lhs);
/* If this is an OR operation, invert both sides; now, the result
should be always false to get a warning. */
......@@ -204,11 +220,11 @@ warn_logical_operator (location_t location, enum tree_code code, tree type,
if (tem && integer_zerop (tem))
return;
op_right = unshare_expr (op_right);
walk_tree_without_duplicates (&op_right, unwrap_c_maybe_const, NULL);
rhs = make_range (op_right, &in1_p, &low1, &high1, &strict_overflow_p);
if (!rhs)
return;
if (TREE_CODE (rhs) == C_MAYBE_CONST_EXPR)
rhs = C_MAYBE_CONST_EXPR_EXPR (rhs);
/* If this is an OR operation, invert both sides; now, the result
should be always false to get a warning. */
......
2017-05-09 Marek Polacek <polacek@redhat.com>
PR c/80525
* c-c++-common/Wlogical-op-1.c: Don't use -fwrapv anymore.
* c-c++-common/Wlogical-op-2.c: New test.
2017-05-09 Senthil Kumar Selvaraj <senthil_kumar.selvaraj@atmel.com>
* gcc.dg/tree-ssa/cunroll-13.c: Use __INT32_TYPE__ for
......
/* PR c/63357 */
/* { dg-do compile } */
/* For -fwrapv see PR80525, xfailing the subtest isn't possible as it passes
with the C++ FE which doesn't have maybe_const_expr. */
/* { dg-options "-fwrapv -Wlogical-op" } */
/* { dg-options "-Wlogical-op" } */
#ifndef __cplusplus
# define bool _Bool
......
/* PR c/80525 */
/* { dg-do compile } */
/* { dg-options "-Wlogical-op" } */
int
fn (int a, int b)
{
if ((a + 1) && (a + 1)) /* { dg-warning "logical .and. of equal expressions" } */
return a;
if ((a + 1) || (a + 1)) /* { dg-warning "logical .or. of equal expressions" } */
return b;
}
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