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re PR c/43772 (Errant -Wlogical-op warning when testing limits) 

2012-05-05  Manuel López-Ibáñez  <manu@gcc.gnu.org>

	PR c/43772
c-family/
	* c-common.c (warn_logical_operator): Do not warn if either side
	is already true or false.
testsuite/
	* c-c++-common/pr43772.c: New.

From-SVN: r187194
This commit is contained in:
Manuel López-Ibáñez 2012-05-05 11:30:57 +00:00
parent 8f75db9fd3
commit f2c4a78515
3 changed files with 44 additions and 14 deletions
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6
gcc/c-family/ChangeLog
View File

@ -1,3 +1,9 @@
2012-05-05 Manuel López-Ibáñez <manu@gcc.gnu.org>
PR c/43772
* c-common.c (warn_logical_operator): Do not warn if either side
is already true or false.
2012-05-04 Manuel López-Ibáñez <manu@gcc.gnu.org>
PR c/51712

47
gcc/c-family/c-common.c
View File

@ -1612,31 +1612,50 @@ warn_logical_operator (location_t location, enum tree_code code, tree type,
|| INTEGRAL_TYPE_P (TREE_TYPE (op_right))))
return;
lhs = make_range (op_left, &in0_p, &low0, &high0, &strict_overflow_p);
rhs = make_range (op_right, &in1_p, &low1, &high1, &strict_overflow_p);
if (lhs && TREE_CODE (lhs) == C_MAYBE_CONST_EXPR)
/* We first test whether either side separately is trivially true
(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. */
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 (rhs && TREE_CODE (rhs) == C_MAYBE_CONST_EXPR)
/* If this is an OR operation, invert both sides; now, the result
should be always false to get a warning. */
if (or_op)
in0_p = !in0_p;
tem = build_range_check (UNKNOWN_LOCATION, type, lhs, in0_p, low0, high0);
if (integer_zerop (tem))
return;
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; we will invert
again at the end. */
/* If this is an OR operation, invert both sides; now, the result
should be always false to get a warning. */
if (or_op)
in0_p = !in0_p, in1_p = !in1_p;
in1_p = !in1_p;
/* If both expressions are the same, if we can merge the ranges, and we
can build the range test, return it or it inverted. */
if (lhs && rhs && operand_equal_p (lhs, rhs, 0)
tem = build_range_check (UNKNOWN_LOCATION, type, rhs, in1_p, low1, high1);
if (integer_zerop (tem))
return;
/* If both expressions have the same operand, if we can merge the
ranges, and if the range test is always false, then warn. */
if (operand_equal_p (lhs, rhs, 0)
&& merge_ranges (&in_p, &low, &high, in0_p, low0, high0,
in1_p, low1, high1)
&& 0 != (tem = build_range_check (UNKNOWN_LOCATION,
type, lhs, in_p, low, high)))
type, lhs, in_p, low, high))
&& integer_zerop (tem))
{
if (TREE_CODE (tem) != INTEGER_CST)
return;
if (or_op)
warning_at (location, OPT_Wlogical_op,
"logical %<or%> "

5
gcc/testsuite/ChangeLog
View File

@ -1,3 +1,8 @@
2012-05-05 Manuel López-Ibáñez <manu@gcc.gnu.org>
PR c/43772
* c-c++-common/pr43772.c: New.
2012-05-05 Paul Thomas <pault@gcc.gnu.org>
PR fortran/41600