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tree-optimization/114027 - conditional reduction chain

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When we classify a conditional reduction chain as CONST_COND_REDUCTION
we fail to verify all involved conditionals have the same constant.
That's a quite unlikely situation so the following simply disables
such classification when there's more than one reduction statement.

	PR tree-optimization/114027
	* tree-vect-loop.cc (vecctorizable_reduction): Use optimized
	condition reduction classification only for single-element
	chains.

	* gcc.dg/vect/pr114027.c: New testcase.
This commit is contained in:
Richard Biener 2024-02-22 10:50:12 +01:00
parent a0782531b8
commit 549f251f05
2 changed files with 32 additions and 5 deletions
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26
gcc/testsuite/gcc.dg/vect/pr114027.c Normal file
View file

@ -0,0 +1,26 @@
#include "tree-vect.h"
int __attribute__((noipa))
foo (int *f, int n)
{
int res = 0;
for (int i = 0; i < n; ++i)
{
if (f[2*i])
res = 2;
if (f[2*i+1])
res = -2;
}
return res;
}
int f[] = { 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 0 };
int
main ()
{
if (foo (f, 16) != 2)
__builtin_abort ();
return 0;
}

11
gcc/tree-vect-loop.cc
View file

@ -7759,17 +7759,18 @@ vectorizable_reduction (loop_vec_info loop_vinfo,
< GET_MODE_SIZE (SCALAR_TYPE_MODE (TREE_TYPE (vectype_op[i]))))))
vectype_in = vectype_op[i];
if (op.code == COND_EXPR)
/* Record how the non-reduction-def value of COND_EXPR is defined.
??? For a chain of multiple CONDs we'd have to match them up all. */
if (op.code == COND_EXPR && reduc_chain_length == 1)
{
/* Record how the non-reduction-def value of COND_EXPR is defined. */
if (dt == vect_constant_def)
{
cond_reduc_dt = dt;
cond_reduc_val = op.ops[i];
}
if (dt == vect_induction_def
&& def_stmt_info
&& is_nonwrapping_integer_induction (def_stmt_info, loop))
else if (dt == vect_induction_def
&& def_stmt_info
&& is_nonwrapping_integer_induction (def_stmt_info, loop))
{
cond_reduc_dt = dt;
cond_stmt_vinfo = def_stmt_info;