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| author | Kyrylo Tkachov <kyrylo.tkachov@arm.com> | 2018-03-08 15:50:25 +0000 |
|---|---|---|
| committer | Kyrylo Tkachov <ktkachov@gcc.gnu.org> | 2018-03-08 15:50:25 +0000 |
| commit | c8574943c1178b72c96c34eca2f2e684201260f4 (patch) | |
| tree | 005276771a440d1d92a8b12943f3a1ea917fe037 /gcc/recog.c | |
| parent | 24545562ca5ece2615f8178ad6c6eb0be4fe6b3f (diff) | |
| download | gcc-c8574943c1178b72c96c34eca2f2e684201260f4.zip gcc-c8574943c1178b72c96c34eca2f2e684201260f4.tar.gz gcc-c8574943c1178b72c96c34eca2f2e684201260f4.tar.bz2 | |
[AArch64] PR target/84748: Mark *compare_cstore<mode>_insn as clobbering CC reg
In this wrong-code PR the combine pass ends up moving a CC-using instruction past a *compare_cstore<mode>_insn
insn_and_split. After reload the *compare_cstore<mode>_insn splitter ends up generating a SUBS instruction that
clobbers the condition flags, and things go bad.
The solution is simple, the *compare_cstore<mode>_insn pattern should specify that it clobbers the CC register
so that combine (or any other pass) does not assume that it can move CC-using patterns across it.
This patch does that and fixes the testcase.
The testcase FAILs on GCC 8 only, but the buggy pattern is in GCC 6 onwards, so we should backport this as
a latent bug fix after it's had some time to bake in trunk.
Bootstrapped and tested on aarch64-none-linux-gnu.
PR target/84748
* config/aarch64/aarch64.md (*compare_cstore<mode>_insn): Mark pattern
as clobbering CC_REGNUM.
* gcc.c-torture/execute/pr84748.c: New test.
From-SVN: r258366
Diffstat (limited to 'gcc/recog.c')
0 files changed, 0 insertions, 0 deletions