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match.pd: Fix up the recent bitmask_inv_cst_vector_p simplification [PR103417]

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The following testcase is miscompiled since the r12-5489-g0888d6bbe97e10
changes.
The simplification triggers on
(x & 4294967040U) >= 0U
and turns it into:
x <= 255U
which is incorrect, it should fold to 1 because unsigned >= 0U is always
true and normally the
/* Non-equality compare simplifications from fold_binary  */
     (if (wi::to_wide (cst) == min)
       (if (cmp == GE_EXPR)
        { constant_boolean_node (true, type); })
simplification folds that, but this simplification was done earlier.

The simplification correctly doesn't include lt which has the same
reason why it shouldn't be handled, we'll fold it to 0 elsewhere.

But, IMNSHO while it isn't incorrect to handle le and gt there, it is
unnecessary.  Because (x & cst) <= 0U and (x & cst) > 0U should
never appear, again in
/* Non-equality compare simplifications from fold_binary  */
we have a simplification for it:
       (if (cmp == LE_EXPR)
        (eq @2 @1))
       (if (cmp == GT_EXPR)
        (ne @2 @1))))
This is done for
  (cmp (convert?@2 @0) uniform_integer_cst_p@1)
and so should be done for both integers and vectors.
As the bitmask_inv_cst_vector_p simplification only handles
eq and ne for signed types, I think it can be simplified to just
following patch.

2021-11-25  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/103417
	* match.pd ((X & Y) CMP 0): Only handle eq and ne.  Commonalize
	common tests.

	* gcc.c-torture/execute/pr103417.c: New test.
This commit is contained in:
Jakub Jelinek 2021-11-25 10:47:24 +01:00
parent 531dae29a6
commit 94912212d3
2 changed files with 20 additions and 13 deletions
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22
gcc/match.pd
View File

@ -5214,20 +5214,16 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
/* Transform comparisons of the form (X & Y) CMP 0 to X CMP2 Z
where ~Y + 1 == pow2 and Z = ~Y. */
(for cst (VECTOR_CST INTEGER_CST)
(for cmp (le eq ne ge gt)
icmp (le le gt le gt)
(simplify
(cmp (bit_and:c@2 @0 cst@1) integer_zerop)
(with { tree csts = bitmask_inv_cst_vector_p (@1); }
(switch
(if (csts && TYPE_UNSIGNED (TREE_TYPE (@1))
&& (VECTOR_TYPE_P (TREE_TYPE (@1)) || single_use (@2)))
(icmp @0 { csts; }))
(if (csts && !TYPE_UNSIGNED (TREE_TYPE (@1))
&& (cmp == EQ_EXPR || cmp == NE_EXPR)
&& (VECTOR_TYPE_P (TREE_TYPE (@1)) || single_use (@2)))
(for cmp (eq ne)
icmp (le gt)
(simplify
(cmp (bit_and:c@2 @0 cst@1) integer_zerop)
(with { tree csts = bitmask_inv_cst_vector_p (@1); }
(if (csts && (VECTOR_TYPE_P (TREE_TYPE (@1)) || single_use (@2)))
(if (TYPE_UNSIGNED (TREE_TYPE (@1)))
(icmp @0 { csts; })
(with { tree utype = unsigned_type_for (TREE_TYPE (@1)); }
(icmp (convert:utype @0) { csts; }))))))))
(icmp (convert:utype @0) { csts; }))))))))
/* -A CMP -B -> B CMP A. */
(for cmp (tcc_comparison)

11
gcc/testsuite/gcc.c-torture/execute/pr103417.c Normal file
View File

@ -0,0 +1,11 @@
/* PR tree-optimization/103417 */
struct { int a : 8; int b : 24; } c = { 0, 1 };
int
main ()
{
if (c.b && !c.b)
__builtin_abort ();
return 0;
}