[PATCH] D124192: [AMDGPU] Callee must always spill writelane VGPRs

Thu Oct 27 02:43:41 PDT 2022

cdevadas added a comment.

In D124192#3887852 <https://reviews.llvm.org/D124192#3887852>, @foad wrote:

> In D124192#3887770 <https://reviews.llvm.org/D124192#3887770>, @nhaehnle wrote:
>
>> I think that marking this as a TODO here, and then following up with a separate change that does the direct call of `allocateWWMSpill` from register allocation is a decent plan.
>
> Is that something you could do in a separate pass post-RA but pre-VirtRegRewriter, by looking at the VirtRegMap analysis?

A separate pass would be possible with Greedy allocator. But with RegAllocFast, VRM won't be available. Planning to use delegate method (see D134950 <https://reviews.llvm.org/D134950>) in RegAllocFast to notify targets when a physical register is allocated.

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https://reviews.llvm.org/D124192