[all-commits] [llvm/llvm-project] 475cef: [SelectionDAG][AMDGPU] Preserve known bits for dem...

[Keshav Vinayak Jha via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 475cef62595255a34b795472bba330a60058abb0
      https://github.com/llvm/llvm-project/commit/475cef62595255a34b795472bba330a60058abb0
  Author: Keshav Vinayak Jha <31160700+keshavvinayak01 at users.noreply.github.com>
  Date:   2026-07-08 (Wed, 08 Jul 2026)

  Changed paths:
    M llvm/include/llvm/CodeGen/TargetLowering.h
    M llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp
    M llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
    M llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
    M llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
    M llvm/lib/Target/AMDGPU/SIISelLowering.cpp
    M llvm/lib/Target/AMDGPU/SIISelLowering.h
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.1024bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.320bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.512bit.ll
    M llvm/test/CodeGen/AMDGPU/bf16.ll
    M llvm/test/CodeGen/AMDGPU/function-returns.ll

  Log Message:
  -----------
  [SelectionDAG][AMDGPU] Preserve known bits for demoted sret pointers (#203468)

AMDGPU marks sret pointers with high-zero known bits so stores can be
folded into MUBUF base+offset addressing. Explicit sret arguments keep
this information through an AssertZext, but implicit sret lowering
passes the hidden return pointer through `DemoteRegister` as a
`CopyToReg/CopyFromReg` pair, where the fact is not visible to
SelectionDAG known-bits queries.

Add a `TargetLowering` hook for sret pointer known bits and use a shared
helper to materialize those bits as an `AssertZext` for both explicit
and demoted sret pointers.


Validated with llvm-test-depends, the AMDGPU function-returns test, and
the full llvm/test/CodeGen suite.

Assisted-by: Codex

---------

Signed-off-by: Keshav Vinayak Jha <keshavvinayakjha at gmail.com>



To unsubscribe from these emails, change your notification settings at https://github.com/llvm/llvm-project/settings/notifications