On 2021/12/7 20:17, Richard Biener wrote:
>>> + class loop *coldest_loop = coldest_outermost_loop[loop->num];
>>> + if (loop_depth (coldest_loop) < loop_depth (outermost_loop))
>>> + {
>>> + class loop *hotter_loop = hotter_than_inner_loop[loop->num];
>>> + if (!hotter_loop
>>> + || loop_depth (hotter_loop) < loop_depth (outermost_loop))
>>> + return outermost_loop;
>>> +
>>> + /* hotter_loop is between OUTERMOST_LOOP and LOOP like:
>>> + [loop tree root, ..., coldest_loop, ..., outermost_loop, ...,
>>> + hotter_loop, second_coldest_loop, ..., loop]
>>> + return second_coldest_loop to be the hoist target. */
>>> + class loop *aloop;
>>> + for (aloop = hotter_loop->inner; aloop; aloop = aloop->next)
>>> + if (flow_loop_nested_p (aloop, loop))
>> should be:
>>
>> if (aloop == loop || flow_loop_nested_p (aloop, loop))
> OK with that fixed.
>
> Are necessary prerequesites committed to avoid regressions?
> I guess we need to keep a watchful eye and eventually revert
> (or gate with a --param disabled by default) the new behavior if
> severe regressions are discovered.
>
> Thanks and sorry for the repeated delays.
> Richard.
>
Thanks for your review, I learned quite a lot and gained very useful
comments & help through the period :) There are still 3 patches required
to avoid regression or so, I've reorganized them and sent it out.
https://gcc.gnu.org/pipermail/gcc-patches/2021-December/586371.html
In addition, cooked the patch to add option for disable/enable it.
Is it OK to merge it to current patch?
[PATCH] Add option -fhoist-to-cold-loop
gcc/ChangeLog:
* common.opt: New.
* loop-invariant.c (find_invariants_bb):
* tree-ssa-loop-im.c (get_coldest_out_loop):
(can_sm_ref_p):
(loop_invariant_motion_in_fun):
---
gcc/common.opt | 4 ++++
gcc/loop-invariant.c | 2 +-
gcc/tree-ssa-loop-im.c | 33 ++++++++++++++++++++++-----------
3 files changed, 27 insertions(+), 12 deletions(-)
diff --git a/gcc/common.opt b/gcc/common.opt
index b921f5e3b25..62b82bd8b95 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -1171,6 +1171,10 @@ fcode-hoisting
Common Var(flag_code_hoisting) Optimization
Enable code hoisting.
+fhoist-to-cold-loop
+Common Var(flag_hoist_to_cold_loop) Init(1) Optimization
+Enable hoisting code to cold loop.
+
fcombine-stack-adjustments
Common Var(flag_combine_stack_adjustments) Optimization
Looks for opportunities to reduce stack adjustments and stack references.
diff --git a/gcc/loop-invariant.c b/gcc/loop-invariant.c
index 5c3be7bf0eb..75b9dd47cd7 100644
--- a/gcc/loop-invariant.c
+++ b/gcc/loop-invariant.c
@@ -1189,7 +1189,7 @@ find_invariants_bb (class loop *loop, basic_block bb,
bool always_reached,
rtx_insn *insn;
basic_block preheader = loop_preheader_edge (loop)->src;
- if (preheader->count > bb->count)
+ if (flag_hoist_to_cold_loop && preheader->count > bb->count)
return;
FOR_BB_INSNS (bb, insn)
diff --git a/gcc/tree-ssa-loop-im.c b/gcc/tree-ssa-loop-im.c
index 565ee62d3f7..d745f66851b 100644
--- a/gcc/tree-ssa-loop-im.c
+++ b/gcc/tree-ssa-loop-im.c
@@ -450,6 +450,9 @@ static class loop *
get_coldest_out_loop (class loop *outermost_loop, class loop *loop,
basic_block curr_bb)
{
+ if (!flag_hoist_to_cold_loop)
+ return outermost_loop;
+
gcc_assert (outermost_loop == loop
|| flow_loop_nested_p (outermost_loop, loop));
@@ -3031,8 +3034,9 @@ can_sm_ref_p (class loop *loop, im_mem_ref *ref)
/* Verify whether the candidate is hot for LOOP. Only do store motion if the
candidate's profile count is hot. Statement in cold BB shouldn't be moved
out of it's loop_father. */
- if (!for_all_locs_in_loop (loop, ref, ref_in_loop_hot_body (loop)))
- return false;
+ if (flag_hoist_to_cold_loop)
+ if (!for_all_locs_in_loop (loop, ref, ref_in_loop_hot_body (loop)))
+ return false;
return true;
}
@@ -3373,8 +3377,11 @@ tree_ssa_lim_finalize (void)
free (bb_loop_postorder);
- coldest_outermost_loop.release ();
- hotter_than_inner_loop.release ();
+ if (flag_hoist_to_cold_loop)
+ {
+ coldest_outermost_loop.release ();
+ hotter_than_inner_loop.release ();
+ }
}
/* Moves invariants from loops. Only "expensive" invariants are moved out --
@@ -3396,13 +3403,17 @@ loop_invariant_motion_in_fun (function *fun, bool
store_motion)
/* Pre-compute coldest outermost loop and nearest hotter loop of each loop.
*/
- class loop *loop;
- coldest_outermost_loop.create (number_of_loops (cfun));
- coldest_outermost_loop.safe_grow_cleared (number_of_loops (cfun));
- hotter_than_inner_loop.create (number_of_loops (cfun));
- hotter_than_inner_loop.safe_grow_cleared (number_of_loops (cfun));
- for (loop = current_loops->tree_root->inner; loop != NULL; loop = loop->next)
- fill_coldest_and_hotter_out_loop (loop, NULL, loop);
+ if (flag_hoist_to_cold_loop)
+ {
+ class loop *loop;
+ coldest_outermost_loop.create (number_of_loops (cfun));
+ coldest_outermost_loop.safe_grow_cleared (number_of_loops (cfun));
+ hotter_than_inner_loop.create (number_of_loops (cfun));
+ hotter_than_inner_loop.safe_grow_cleared (number_of_loops (cfun));
+ for (loop = current_loops->tree_root->inner; loop != NULL;
+ loop = loop->next)
+ fill_coldest_and_hotter_out_loop (loop, NULL, loop);
+ }
int *rpo = XNEWVEC (int, last_basic_block_for_fn (fun));
int n = pre_and_rev_post_order_compute_fn (fun, NULL, rpo, false);
--
2.27.0.90.geebb51ba8c
