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middle-end: don't cache restart_loop in vectorizable_live_operations [PR113808]

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There's a bug in vectorizable_live_operation that restart_loop is defined
outside the loop.

This variable is supposed to indicate whether we are doing a first or last
index reduction.  The problem is that by defining it outside the loop it becomes
dependent on the order we visit the USE/DEFs.

In the given example, the loop isn't PEELED, but we visit the early exit uses
first.  This then sets the boolean to true and it can't get to false again.

So when we visit the main exit we still treat it as an early exit for that
SSA name.

This cleans it up and renames the variables to something that's hopefully
clearer to their intention.

gcc/ChangeLog:

	PR tree-optimization/113808
	* tree-vect-loop.cc (vectorizable_live_operation): Don't cache the
	value cross iterations.

gcc/testsuite/ChangeLog:

	PR tree-optimization/113808
	* gfortran.dg/vect/vect-early-break_1-PR113808.f90: New test.
This commit is contained in:
Tamar Christina 2024-02-08 10:43:13 +00:00
parent e515d813f0
commit 3f69db1812
2 changed files with 23 additions and 3 deletions
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21
gcc/testsuite/gfortran.dg/vect/vect-early-break_1-PR113808.f90 Normal file
View file

@ -0,0 +1,21 @@
! { dg-add-options vect_early_break }
! { dg-require-effective-target vect_early_break }
! { dg-require-effective-target vect_long_long }
! { dg-additional-options "-fopenmp-simd" }
! { dg-final { scan-tree-dump "LOOP VECTORIZED" "vect" } }
program main
integer :: n, i,k
n = 11
do i = 1, n,2
!$omp simd lastprivate(k)
do k = 1, i + 41
if (k > 11 + 41 .or. k < 1) error stop
end do
end do
if (k /= 53) then
print *, k, 53
error stop
endif
end

5
gcc/tree-vect-loop.cc
View file

@ -10950,7 +10950,7 @@ vectorizable_live_operation (vec_info *vinfo, stmt_vec_info stmt_info,
did. For the live values we want the value at the start of the iteration
rather than at the end. */
edge main_e = LOOP_VINFO_IV_EXIT (loop_vinfo);
bool restart_loop = LOOP_VINFO_EARLY_BREAKS_VECT_PEELED (loop_vinfo);
bool all_exits_as_early_p = LOOP_VINFO_EARLY_BREAKS_VECT_PEELED (loop_vinfo);
FOR_EACH_IMM_USE_STMT (use_stmt, imm_iter, lhs)
if (!is_gimple_debug (use_stmt)
&& !flow_bb_inside_loop_p (loop, gimple_bb (use_stmt)))
@ -10966,8 +10966,7 @@ vectorizable_live_operation (vec_info *vinfo, stmt_vec_info stmt_info,
/* For early exit where the exit is not in the BB that leads
to the latch then we're restarting the iteration in the
scalar loop. So get the first live value. */
restart_loop = restart_loop || !main_exit_edge;
if (restart_loop
if ((all_exits_as_early_p || !main_exit_edge)
&& STMT_VINFO_DEF_TYPE (stmt_info) == vect_induction_def)
{
tmp_vec_lhs = vec_lhs0;