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tree-optimization/122308 - apply LIM after unroll-and-jam 

Just like with loop interchange, unroll-and-jam can leave invariant
stmts in the inner loop from outer loop stmts inbetween the two
inner loop copies.  Do a per-function invariant motion when we
applied unroll-and-jam.  This avoids failed dataref analysis
and fallback to gather/scatter during vectorization.

	PR tree-optimization/122308
	* gimple-loop-jam.cc (tree_loop_unroll_and_jam): Do LIM
	after applying unroll-and-jam.

	* gcc.dg/vect/vect-pr122308.c: New testcase.
This commit is contained in:
Richard Biener 2025-10-17 15:12:11 +02:00
parent 7cd91c7c42
commit d6986e06db
2 changed files with 21 additions and 0 deletions
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1
gcc/gimple-loop-jam.cc
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@ -641,6 +641,7 @@ tree_loop_unroll_and_jam (void)
{
cleanup_tree_cfg ();
todo &= ~TODO_cleanup_cfg;
todo |= loop_invariant_motion_in_fun (cfun, false);
}
rewrite_into_loop_closed_ssa (NULL, 0);
scev_reset ();

20
gcc/testsuite/gcc.dg/vect/vect-pr122308.c Normal file
View File

@ -0,0 +1,20 @@
/* { dg-do compile } */
/* { dg-additional-options "-O3 -fdump-tree-unrolljam-optimized" } */
int a[1024];
int b[2048];
int c[2048];
void foo(int n)
{
for (int i = 0; i < n; i++)
{
int index = c[i];
for (int j = 0; j < 1024; ++j)
a[j] += b[index + j];
}
}
/* { dg-final { scan-tree-dump "optimized: applying unroll and jam" "unrolljam" } } */
/* { dg-final { scan-tree-dump-times "optimized: loop vectorized" 2 "vect" { target vect_int } } } */