[PATCH] D129073: [AMDGPU] Combine s_or_saveexec, s_xor instructions.

[Stanislav Mekhanoshin via Phabricator via llvm-commits]

rampitec added a comment.

In D129073#3635410 <https://reviews.llvm.org/D129073#3635410>, @nhaehnle wrote:

> 1. Scanning over entire basic blocks is bad for compile times, and this pass is already doing some scans. For example, `optimizeExecSequence` already scans for copies to exec. Can this be improved? Notice how the scan in `optimizeExecSequence` goes backwards in the basic block and limits itself to only a small number of instruction. I could imagine a restructuring of the pass so that every basic block is scanned backwards for an EXEC-writing instruction. Depending on what the instruction is (copy-to-exec, s_and_saveexec, s_xor) one of the optimizations can be applied.

It can probably start from the first terminator, scan backwards, and bail with the first instruction not modifying the exec.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D129073/new/

https://reviews.llvm.org/D129073