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* [gcc r13-5325] tree-optimization/108500 - avoid useless fast-query compute in CFG cleanup
@ 2023-01-24 14:29 Richard Biener
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From: Richard Biener @ 2023-01-24 14:29 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:f31fa9ea35ebcf221a2abaacba5511225f5d036e
commit r13-5325-gf31fa9ea35ebcf221a2abaacba5511225f5d036e
Author: Richard Biener <rguenther@suse.de>
Date: Tue Jan 24 10:49:18 2023 +0100
tree-optimization/108500 - avoid useless fast-query compute in CFG cleanup
CFG cleanup computes dominators before the loop over blocks looking
for merging opportunities. That computes also the fast-query DFS
numbers but that's a bit pointless since any CFG cleanup will invalidate
them immediately (they are re-computed before fixing up loops).
The following avoids this and fixes the SIGSEGV due to the deep
recursion in assign_dfs_numbers after inlining very many small
functions.
PR tree-optimization/108500
* dominance.h (calculate_dominance_info): Add parameter
to indicate fast-query compute, defaulted to true.
* dominance.cc (calculate_dominance_info): Honor
fast-query compute parameter.
* tree-cfgcleanup.cc (cleanup_tree_cfg_noloop): Do
not compute the dominator fast-query DFS numbers.
Diff:
---
gcc/dominance.cc | 9 ++++++---
gcc/dominance.h | 2 +-
gcc/tree-cfgcleanup.cc | 6 ++++--
3 files changed, 11 insertions(+), 6 deletions(-)
diff --git a/gcc/dominance.cc b/gcc/dominance.cc
index 13d5498443b..099b8fd3f24 100644
--- a/gcc/dominance.cc
+++ b/gcc/dominance.cc
@@ -705,10 +705,12 @@ compute_dom_fast_query_in_region (enum cdi_direction dir,
}
/* The main entry point into this module. DIR is set depending on whether
- we want to compute dominators or postdominators. */
+ we want to compute dominators or postdominators. If COMPUTE_FAST_QUERY
+ is false then the DFS numbers allowing for a O(1) dominance query
+ are not computed. */
void
-calculate_dominance_info (cdi_direction dir)
+calculate_dominance_info (cdi_direction dir, bool compute_fast_query)
{
unsigned int dir_index = dom_convert_dir_to_idx (dir);
@@ -745,7 +747,8 @@ calculate_dominance_info (cdi_direction dir)
else
checking_verify_dominators (dir);
- compute_dom_fast_query (dir);
+ if (compute_fast_query)
+ compute_dom_fast_query (dir);
timevar_pop (TV_DOMINANCE);
}
diff --git a/gcc/dominance.h b/gcc/dominance.h
index abdcf76e6f2..3c5a345f478 100644
--- a/gcc/dominance.h
+++ b/gcc/dominance.h
@@ -35,7 +35,7 @@ enum dom_state
DOM_OK /* Everything is ok. */
};
-extern void calculate_dominance_info (enum cdi_direction);
+extern void calculate_dominance_info (enum cdi_direction, bool = true);
extern void calculate_dominance_info_for_region (enum cdi_direction,
vec<basic_block>);
extern void free_dominance_info (function *, enum cdi_direction);
diff --git a/gcc/tree-cfgcleanup.cc b/gcc/tree-cfgcleanup.cc
index ca0cb633f2c..64ff16fc45b 100644
--- a/gcc/tree-cfgcleanup.cc
+++ b/gcc/tree-cfgcleanup.cc
@@ -1106,9 +1106,11 @@ cleanup_tree_cfg_noloop (unsigned ssa_update_flags)
timevar_push (TV_TREE_CLEANUP_CFG);
}
- /* Compute dominator info which we need for the iterative process below. */
+ /* Compute dominator info which we need for the iterative process below.
+ Avoid computing the fast query DFS numbers since any block merging
+ done will invalidate them anyway. */
if (!dom_info_available_p (CDI_DOMINATORS))
- calculate_dominance_info (CDI_DOMINATORS);
+ calculate_dominance_info (CDI_DOMINATORS, false);
else
checking_verify_dominators (CDI_DOMINATORS);
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