[all-commits] [llvm/llvm-project] 6ea714: [AMDGPU][SDAG] Add ISD::PTRADD DAG combines

[Fabian Ritter via All-commits]

  Branch: refs/heads/users/ritter-x2a/06-04-_amdgpu_sdag_add_isd_ptradd_dag_combines
  Home:   https://github.com/llvm/llvm-project
  Commit: 6ea714e83e4714d9fe025e5e9fee48b41f223cb8
      https://github.com/llvm/llvm-project/commit/6ea714e83e4714d9fe025e5e9fee48b41f223cb8
  Author: Fabian Ritter <fabian.ritter at amd.com>
  Date:   2025-06-13 (Fri, 13 Jun 2025)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    M llvm/lib/Target/AMDGPU/SIISelLowering.cpp
    M llvm/lib/Target/AMDGPU/SIISelLowering.h
    M llvm/test/CodeGen/AMDGPU/ptradd-sdag-optimizations.ll

  Log Message:
  -----------
  [AMDGPU][SDAG] Add ISD::PTRADD DAG combines

This patch focuses on generic DAG combines, plus an AMDGPU-target-specific one
that is closely connected.

The generic DAG combine is based on a part of PR #105669 by @rgwott, which was
adapted from work by @jrtc27, @arichardson, @davidchisnall in the CHERI/Morello
LLVM tree. I added some parts and removed several disjuncts from the
reassociation condition:
- `isNullConstant(X)`, since there are address spaces where 0 is a perfectly
  normal value that shouldn't be treated specially,
- `(YIsConstant && ZOneUse)` and `(N0OneUse && ZOneUse && !ZIsConstant)`, since
  they cause regressions in AMDGPU.

For SWDEV-516125.


  Commit: 493b8dffef14efde860f261058b44534e473dca5
      https://github.com/llvm/llvm-project/commit/493b8dffef14efde860f261058b44534e473dca5
  Author: Fabian Ritter <fabian.ritter at amd.com>
  Date:   2025-06-13 (Fri, 13 Jun 2025)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

  Log Message:
  -----------
  Remove undef/poison operand handling from the PTRADD dag combine

Those are folded earlier already.


  Commit: b638ab5177195608f361825ec6712abb461dba51
      https://github.com/llvm/llvm-project/commit/b638ab5177195608f361825ec6712abb461dba51
  Author: Fabian Ritter <fabian.ritter at amd.com>
  Date:   2025-06-13 (Fri, 13 Jun 2025)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    M llvm/lib/Target/AMDGPU/SIISelLowering.cpp

  Log Message:
  -----------
  Bail out early in the generic combine to reduce identation, add a comment referring to the target-specific reassociation there, and remove a currently unused variable in the target-specific combine.


  Commit: 7f793488af6c3db20f26744bbcf60e933dcb3752
      https://github.com/llvm/llvm-project/commit/7f793488af6c3db20f26744bbcf60e933dcb3752
  Author: Fabian Ritter <fabian.ritter at amd.com>
  Date:   2025-06-13 (Fri, 13 Jun 2025)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

  Log Message:
  -----------
  Add an explicit PtrVT == IntVT to the (ptradd 0, x) -> x fold


  Commit: 0b77a8febb7a503a1b70f48edf093ac03fa162ac
      https://github.com/llvm/llvm-project/commit/0b77a8febb7a503a1b70f48edf093ac03fa162ac
  Author: Fabian Ritter <fabian.ritter at amd.com>
  Date:   2025-06-13 (Fri, 13 Jun 2025)

  Changed paths:
    A llvm/test/CodeGen/AMDGPU/ptradd-sdag-undef-poison.ll

  Log Message:
  -----------
  Add a test for poison/undef folds.


  Commit: 554316be0c1604efe1658c0ba99cc6686ecb71e5
      https://github.com/llvm/llvm-project/commit/554316be0c1604efe1658c0ba99cc6686ecb71e5
  Author: Fabian Ritter <fabian.ritter at amd.com>
  Date:   2025-06-13 (Fri, 13 Jun 2025)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    M llvm/lib/Target/AMDGPU/SIISelLowering.cpp

  Log Message:
  -----------
  Implement reviewer suggestions


Compare: https://github.com/llvm/llvm-project/compare/760e22ec23b4...554316be0c16

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