[all-commits] [llvm/llvm-project] 55ce38: [CodeGen] Use validated wave counts for AMDGPU spi...

[Yaxun (Sam) Liu via All-commits]

  Branch: refs/heads/users/yxsamliu/pgo-wave-profiled-spill
  Home:   https://github.com/llvm/llvm-project
  Commit: 55ce386fb935bf07bac79a876c402e214480f3ba
      https://github.com/llvm/llvm-project/commit/55ce386fb935bf07bac79a876c402e214480f3ba
  Author: Yaxun (Sam) Liu <yaxun.liu at amd.com>
  Date:   2026-09-24 (Thu, 24 Sep 2026)

  Changed paths:
    M llvm/lib/CodeGen/SpillPlacement.cpp
    A llvm/test/CodeGen/AMDGPU/wave-profile-spill.mir

  Log Message:
  -----------
  [CodeGen] Use validated wave counts for AMDGPU spill costs

Lane-based block frequencies can understate the cost of a spill in
divergent GPU code: a wave still executes a block with only some lanes
active. Use measured block-wave counts to weight SpillPlacement's costs
relative to the original entry-wave count.

Opt in on AMDGPU only. Accept a measured count only when its IR block
maps uniquely to a machine block with matching predecessors and
successors. Keep the existing MBFI cost for unmeasured or rejected
blocks, and leave branch probabilities and general BFI unchanged.



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