gnu /
gcc /
8b3e6dbe51362204d2c3544892720c7cea30b08c [committed][PR rtl-optimization/120550] Drop REG_EQUAL note after ext-dce transformation
This bug was found by Edwin's fuzzing efforts on RISC-V, though it likely
affects other targets.
In simplest terms when ext-dce converts an extension into a (possibly
simplified) subreg copy it may make an attached REG_EQUAL note invalid.
In the case Edwin found the note was an extension, but I don't think that would
necessarily always be the case. The note could have other forms which
potentially need invalidation. So the safest thing to do is just remove any
attached REG_EQUAL or REG_EQUIV note.
Note adjusting Edwin's testcase in the obvious way to avoid having to interpret
printf output for pass/fail status makes the bug go latent. That's why no
testcase is included with this patch.
Bootstrapped and regression tested on x86_64. Obviously also verified it fixes
the testcase Edwin filed.
This is a good candidate for cherry-picking to the gcc-15 release branch after
simmering on the trunk a bit.
PR rtl-optimization/120550
gcc/
* ext-dce.cc (ext_dce_try_optimize_insn): Drop REG_EQUAL/REG_EQUIV
notes on modified insns.
(cherry picked from commit 34e1e5e33ec3eb475c0c8278800b6fc246a86763)
1 file changed
