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PR tree-optimization/59124 (bogus -Warray-bounds warning)

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gcc/ChangeLog:

	PR tree-optimization/59124
	* tree-vrp.c (register_edge_assert_for_2): For NAME != CST1
	where NAME = A +- CST2 add the assertion A != (CST1 -+ CST2).

gcc/testsuite/ChangeLog:

	PR tree-optimization/59124
	* gcc.dg/Warray-bounds-19.c: New test.

From-SVN: r234544
This commit is contained in:
Patrick Palka 2016-03-30 00:55:00 +00:00
parent 3c258984f4
commit d014a712e0
4 changed files with 49 additions and 0 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2016-03-30 Patrick Palka <ppalka@gcc.gnu.org>
PR tree-optimization/59124
* tree-vrp.c (register_edge_assert_for_2): For NAME != CST1
where NAME = A +- CST2 add the assertion A != (CST1 -+ CST2).
2016-03-29 Jeff Law <law@redhat.com>
* tree-ssa-coalesce.c (struct ssa_conflicts): Fix typo in

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2016-03-30 Patrick Palka <ppalka@gcc.gnu.org>
PR tree-optimization/59124
* gcc.dg/Warray-bounds-19.c: New test.
2016-03-29 Zachary T Welch <zwelch@codesourcery.com>
* lib/prune.exp (escape_regex_chars): New.

17
gcc/testsuite/gcc.dg/Warray-bounds-19.c Normal file
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@ -0,0 +1,17 @@
/* PR tree-optimization/59124 */
/* { dg-options "-O3 -Warray-bounds" } */
unsigned baz[6];
void foo(unsigned *bar, unsigned n)
{
unsigned i, j;
if (n > 6)
n = 6;
for (i = 1; i < n; i++)
for (j = i - 1; j > 0; j--)
bar[j - 1] = baz[j - 1];
}

21
gcc/tree-vrp.c
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@ -5310,6 +5310,27 @@ register_edge_assert_for_2 (tree name, edge e, gimple_stmt_iterator bsi,
if (is_gimple_assign (def_stmt))
rhs_code = gimple_assign_rhs_code (def_stmt);
/* In the case of NAME != CST1 where NAME = A +- CST2 we can
assert that A != CST1 -+ CST2. */
if ((comp_code == EQ_EXPR || comp_code == NE_EXPR)
&& (rhs_code == PLUS_EXPR || rhs_code == MINUS_EXPR))
{
tree op0 = gimple_assign_rhs1 (def_stmt);
tree op1 = gimple_assign_rhs2 (def_stmt);
if (TREE_CODE (op0) == SSA_NAME
&& TREE_CODE (op1) == INTEGER_CST
&& live_on_edge (e, op0)
&& !has_single_use (op0))
{
enum tree_code reverse_op = (rhs_code == PLUS_EXPR
? MINUS_EXPR : PLUS_EXPR);
op1 = int_const_binop (reverse_op, val, op1);
if (TREE_OVERFLOW (op1))
op1 = drop_tree_overflow (op1);
register_new_assert_for (op0, op0, comp_code, op1, NULL, e, bsi);
}
}
/* Add asserts for NAME cmp CST and NAME being defined
as NAME = (int) NAME2. */
if (!TYPE_UNSIGNED (TREE_TYPE (val))