[all-commits] [llvm/llvm-project] 525117: [AMDGPU] Fix SSID merge in SIMemoryLegalizer to us...

[Wooseok Lee via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 52511761bc80e96b7d07b4da71bb08c8f498dee1
      https://github.com/llvm/llvm-project/commit/52511761bc80e96b7d07b4da71bb08c8f498dee1
  Author: Wooseok Lee <wolee at amd.com>
  Date:   2026-07-13 (Mon, 13 Jul 2026)

  Changed paths:
    M llvm/lib/Target/AMDGPU/AMDGPUMachineModuleInfo.h
    M llvm/lib/Target/AMDGPU/SIMemoryLegalizer.cpp
    M llvm/test/CodeGen/AMDGPU/av-invalid-scope.ll
    M llvm/test/CodeGen/AMDGPU/memory-legalizer-invalid-syncscope.ll
    M llvm/test/CodeGen/AMDGPU/memory-legalizer-multiple-mem-operands-atomics.mir

  Log Message:
  -----------
  [AMDGPU] Fix SSID merge in SIMemoryLegalizer to use smallest inclusiv… (#208300)

…e scope

SIMemOpAccess::constructFromMIWithMMO merged multiple MMO sync scopes by
calling isSyncScopeInclusion(A, B) and blindly overwriting SSID with B
when it returned false. This was correct when B strictly subsumes A, but
isSyncScopeInclusion returned false for both "A < B" and "A and B are
incomparable" -- e.g. agent-one-as (one-AS, agent level) vs workgroup
(cross-AS, workgroup level) live on different branches of the
two-dimensional scope lattice and neither subsumes the other. In the
incomparable case the resulting SSID depended on MMO order, silently
dropping agent-scope cache-management requirements.

Fix: replace isSyncScopeInclusion (std::optional<bool>) with
getMergedSyncScopeID (std::optional<SyncScope::ID>) which returns the
smallest scope inclusive of both inputs. The merged level is
max(level_A, level_B); if either input is cross-AS the result is also
cross-AS, since dropping cross-AS ordering would silently lose the
ordering guarantee for address spaces not covered by a one-AS scope.

Add tests in memory-legalizer-multiple-mem-operands-atomics.mir
verifying that a FLAT_ATOMIC_ADD with agent-one-as and workgroup MMOs
produces agent-scope cache ops (BUFFER_WBINVL1_VOL) regardless of MMO
order.



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