mirror of
https://github.com/RPCSX/llvm.git
synced 2025-03-01 01:15:55 +00:00
97c0826552
The fast register-allocator cannot cope with inter-block dependencies without spilling. This is fine for ldrex/strex loops coming from atomicrmw instructions where any value produced within a block is dead by the end, but not for cmpxchg. So we lower a cmpxchg at -O0 via a pseudo-inst that gets expanded after regalloc. Fortunately this is at -O0 so we don't have to care about performance. This simplifies the various axes of expansion considerably: we assume a strong seq_cst operation and ensure ordering via the always-present DMB instructions rather than v8 acquire/release instructions. Should fix the 32-bit part of PR25526. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@266679 91177308-0d34-0410-b5e6-96231b3b80d8