[all-commits] [llvm/llvm-project] f7e416: [AMDGPU] Clamp load_monitor scope to minimum SCOPE...

[Sameer Sahasrabuddhe via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: f7e4167f816ac8c5a6e553c66f3b90fe040d1362
      https://github.com/llvm/llvm-project/commit/f7e4167f816ac8c5a6e553c66f3b90fe040d1362
  Author: Sameer Sahasrabuddhe <sameer.sahasrabuddhe at amd.com>
  Date:   2026-06-09 (Tue, 09 Jun 2026)

  Changed paths:
    M llvm/docs/AMDGPUUsage.rst
    M llvm/lib/Target/AMDGPU/SIInstrInfo.h
    M llvm/lib/Target/AMDGPU/SIMemoryLegalizer.cpp
    M llvm/test/CodeGen/AMDGPU/llvm.amdgcn.load.monitor.gfx1250.ll

  Log Message:
  -----------
  [AMDGPU] Clamp load_monitor scope to minimum SCOPE_SE (#198245)

The load_monitor instructions monitor L2 cache lines and therefore
require at least SCOPE_SE to ensure the L2 cache is hit. The current
memory model requires the user to ensure that the specified scope is
such that it results in at least SCOPE_SE, otherwise the behaviour is
undefined. Instead, we now clamp the emitted scope at a minimum of
SCOPE_SE, so that the undefined behaviour is converted into a
performance loss instead.

Assisted-By: Claude Opus 4.6



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