https://gcc.gnu.org/g:d629308c699bb8fe90c2afeb7fa1acb12cb5526b
commit r13-8763-gd629308c699bb8fe90c2afeb7fa1acb12cb5526b
Author: Richard Biener <rguent...@suse.de>
Date: Mon Feb 19 11:10:50 2024 +0100
rtl-optimization/54052 - RTL SSA PHI insertion compile-time hog
The following tries to address the PHI insertion compile-time hog in
RTL fwprop observed with the PR54052 testcase where the loop computing
the "unfiltered" set of variables possibly needing PHI nodes for each
block exhibits quadratic compile-time and memory-use.
It does so by pruning the local DEFs with LR_OUT of the block, removing
regs that can never be LR_IN (defined by this block) in the dominance
frontier.
PR rtl-optimization/54052
* rtl-ssa/blocks.cc (function_info::place_phis): Filter
local defs by LR_OUT.
(cherry picked from commit c7151283dc747769d4ac4f216d8f519bda2569b5)
Diff:
---
gcc/rtl-ssa/blocks.cc | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/gcc/rtl-ssa/blocks.cc b/gcc/rtl-ssa/blocks.cc
index 1f9969d78d88..0ee9fa0d6a2a 100644
--- a/gcc/rtl-ssa/blocks.cc
+++ b/gcc/rtl-ssa/blocks.cc
@@ -639,7 +639,12 @@ function_info::place_phis (build_info &bi)
if (bitmap_empty_p (&frontiers[b1]))
continue;
- bitmap b1_def = &DF_LR_BB_INFO (BASIC_BLOCK_FOR_FN (m_fn, b1))->def;
+ // Defs in B1 that are possibly in LR_IN in the dominance frontier
+ // blocks.
+ auto_bitmap b1_def;
+ bitmap_and (b1_def, &DF_LR_BB_INFO (BASIC_BLOCK_FOR_FN (m_fn, b1))->def,
+ DF_LR_OUT (BASIC_BLOCK_FOR_FN (m_fn, b1)));
+
bitmap_iterator bmi;
unsigned int b2;
EXECUTE_IF_SET_IN_BITMAP (&frontiers[b1], 0, b2, bmi)
