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| author | Tim Northover <tnorthover@apple.com> | 2016-12-01 21:31:59 +0000 |
|---|---|---|
| committer | Tim Northover <tnorthover@apple.com> | 2016-12-01 21:31:59 +0000 |
| commit | 5bb87b6769aaabae141d76ddbf705f2aca566b6c (patch) | |
| tree | c1741863629f754018a9d35247cfb8c9dd4523f9 /llvm/utils/vim/syntax/tablegen.vim | |
| parent | 873947141b376ad1691ddc66881020de4ce91f7e (diff) | |
| download | bcm5719-llvm-5bb87b6769aaabae141d76ddbf705f2aca566b6c.tar.gz bcm5719-llvm-5bb87b6769aaabae141d76ddbf705f2aca566b6c.zip | |
AArch64: fix 128-bit cmpxchg at -O0 (again, again).
This time the issue is fortunately just a simple mistake rather than a horrible
design spectre. I thought SUBS/SBCS provided sufficient NZCV flags for
comparing two 64-bit values, but they don't.
The fix is slightly clunkier in AArch64 because we can't use conditional
execution to emit a pair of CMPs. Traditionally an "icmp ne i128" would map to
an EOR/EOR/ORR/CBNZ, but that uses more registers so it's easier to go with a
CSET/CINC/CBNZ combination. Slightly less efficient, but this is -O0 anyway.
Thanks to Anton Korobeynikov for pointing out the issue.
llvm-svn: 288418
Diffstat (limited to 'llvm/utils/vim/syntax/tablegen.vim')
0 files changed, 0 insertions, 0 deletions
