https://gcc.gnu.org/g:d6d7da92fb598c50d25332011bffe6b6515c9669
commit r15-7854-gd6d7da92fb598c50d25332011bffe6b6515c9669
Author: Alex Coplan <alex.cop...@arm.com>
Date: Wed Mar 5 15:45:09 2025 +0000
pair-fusion: Add singleton move_range asserts [PR114492]
The PR claims that pair-fusion has invalid uses of gcc_assert (such that
the pass will misbehave with --disable-checking). As noted in the
comments, in the case of the calls to restrict_movement, the only way we
can possibly depend on the side effects is if we call it with a
non-singleton move range. However, the intent is that we always have a
singleton move range here, and thus we do not rely on the side effects.
This patch therefore adds asserts to check for a singleton move range
before calling restrict_movement, thus clarifying the intent and
hopefully dispelling any concerns that having the calls wrapped in
asserts is problematic here.
gcc/ChangeLog:
PR rtl-optimization/114492
* pair-fusion.cc (pair_fusion_bb_info::fuse_pair): Check for
singleton
move range before calling restrict_movement.
(pair_fusion::try_promote_writeback): Likewise.
Diff:
---
gcc/pair-fusion.cc | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/gcc/pair-fusion.cc b/gcc/pair-fusion.cc
index 72e642465340..a4ef72879675 100644
--- a/gcc/pair-fusion.cc
+++ b/gcc/pair-fusion.cc
@@ -1994,7 +1994,8 @@ pair_fusion_bb_info::fuse_pair (bool load_p,
auto ignore = ignore_changing_insns (changes);
for (unsigned i = 0; i < changes.length (); i++)
- gcc_assert (rtl_ssa::restrict_movement (*changes[i], ignore));
+ gcc_assert (changes[i]->move_range.singleton ()
+ && rtl_ssa::restrict_movement (*changes[i], ignore));
// Check the pair pattern is recog'd.
if (!rtl_ssa::recog (attempt, *pair_change, ignore))
@@ -3084,7 +3085,8 @@ pair_fusion::try_promote_writeback (insn_info *insn, bool
load_p)
auto ignore = ignore_changing_insns (changes);
for (unsigned i = 0; i < ARRAY_SIZE (changes); i++)
- gcc_assert (rtl_ssa::restrict_movement (*changes[i], ignore));
+ gcc_assert (changes[i]->move_range.singleton ()
+ && rtl_ssa::restrict_movement (*changes[i], ignore));
if (!rtl_ssa::recog (attempt, pair_change, ignore))
{
