[PATCH] D101939: [AMDGPU] Disable the SIFormMemoryClauses pass at -O1

[Jay Foad via Phabricator via llvm-commits]

foad added a comment.

In D101939#2740008 <https://reviews.llvm.org/D101939#2740008>, @arsenm wrote:

> Can we address it being slow instead of just turning of everything that is? There's no reason it should be slow, but the way it uses liveness information is horrible

On small functions I think the run time of this pass is dominated by the two calls to TRI->getAllocatableSet, which means two identical calls to SIRegisterInfo::getReservedRegs, which has a very large fixed cost. Is there some way the Reserved register set can be cached (in the SIMachineFunctionInfo object?)?


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https://reviews.llvm.org/D101939