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vect: Fix inconsistency in fully-masked lane-reducing op generation [PR116985]

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To align vectorized def/use when lane-reducing op is present in loop reduction,
we may need to insert extra trivial pass-through copies, which would cause
mismatch between lane-reducing vector copy and loop mask index. This could be
fixed by computing the right index around a new counter on effective lane-
reducing vector copies.

2024-10-11 Feng Xue <fxue@os.amperecomputing.com>

gcc/
	PR tree-optimization/116985
	* tree-vect-loop.cc (vect_transform_reduction): Compute loop mask
	index based on effective vector copies for reduction op.

gcc/testsuite/
	PR tree-optimization/116985
	* gcc.dg/vect/pr116985.c: New testcase.
This commit is contained in:
Feng Xue 2024-10-11 14:55:05 +08:00
parent f54d42e000
commit a9173a50e7
2 changed files with 28 additions and 2 deletions
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23
gcc/testsuite/gcc.dg/vect/pr116985.c Normal file
View file

@ -0,0 +1,23 @@
/* { dg-do compile } */
/* { dg-require-effective-target vect_int } */
/* { dg-options "--param=vect-partial-vector-usage=2 -O2" } */
/* { dg-additional-options "-mavx512vbmi2" { target { i?86-*-* x86_64-*-* } } } */
/* { dg-additional-options "-march=armv9-a" { target aarch64-*-* } } */
signed int __attribute__ ((noipa))
fn (signed int n,
signed char *restrict a,
signed char *restrict b,
signed char *restrict c,
signed char *restrict d)
{
signed int res = 0;
for (int i = 0; i < n; ++i)
{
res += a[i] * b[i];
res += i + 1;
res += c[i] * d[i];
}
return res;
}

7
gcc/tree-vect-loop.cc
View file

@ -8916,6 +8916,7 @@ vect_transform_reduction (loop_vec_info loop_vinfo,
bool emulated_mixed_dot_prod = vect_is_emulated_mixed_dot_prod (stmt_info);
unsigned num = vec_oprnds[reduc_index == 0 ? 1 : 0].length ();
unsigned mask_index = 0;
for (unsigned i = 0; i < num; ++i)
{
@ -8954,7 +8955,8 @@ vect_transform_reduction (loop_vec_info loop_vinfo,
std::swap (vop[0], vop[1]);
}
tree mask = vect_get_loop_mask (loop_vinfo, gsi, masks,
vec_num * ncopies, vectype_in, i);
vec_num * ncopies, vectype_in,
mask_index++);
gcall *call = gimple_build_call_internal (cond_fn, 4, mask,
vop[0], vop[1], vop[0]);
new_temp = make_ssa_name (vec_dest, call);
@ -8971,7 +8973,8 @@ vect_transform_reduction (loop_vec_info loop_vinfo,
if (masked_loop_p && mask_by_cond_expr)
{
tree mask = vect_get_loop_mask (loop_vinfo, gsi, masks,
vec_num * ncopies, vectype_in, i);
vec_num * ncopies, vectype_in,
mask_index++);
build_vect_cond_expr (code, vop, mask, gsi);
}