[all-commits] [llvm/llvm-project] 2e5c29: [AMDGPU] Add backward compatibility layer for kern...

[Austin Kerbow via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 2e5c2982819625d84e0b61aea0ec00de859f0e95
      https://github.com/llvm/llvm-project/commit/2e5c2982819625d84e0b61aea0ec00de859f0e95
  Author: Austin Kerbow <Austin.Kerbow at amd.com>
  Date:   2025-01-10 (Fri, 10 Jan 2025)

  Changed paths:
    M llvm/docs/AMDGPUUsage.rst
    M llvm/lib/Target/AMDGPU/AMDGPU.h
    M llvm/lib/Target/AMDGPU/AMDGPUArgumentUsageInfo.h
    M llvm/lib/Target/AMDGPU/AMDGPUAsmPrinter.cpp
    A llvm/lib/Target/AMDGPU/AMDGPUPreloadKernArgProlog.cpp
    A llvm/lib/Target/AMDGPU/AMDGPUPreloadKernArgProlog.h
    M llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp
    M llvm/lib/Target/AMDGPU/CMakeLists.txt
    M llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp
    M llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.h
    M llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.cpp
    M llvm/test/CodeGen/AMDGPU/llc-pipeline.ll
    M llvm/test/CodeGen/AMDGPU/preload-implicit-kernargs.ll
    M llvm/test/CodeGen/AMDGPU/preload-kernarg-header.ll
    M llvm/test/CodeGen/AMDGPU/preload-kernargs.ll

  Log Message:
  -----------
  [AMDGPU] Add backward compatibility layer for kernarg preloading (#119167)

Add a prologue to the kernel entry to handle cases where code designed
for kernarg preloading is executed on hardware equipped with
incompatible firmware. If hardware has compatible firmware the 256 bytes
at the start of the kernel entry will be skipped. This skipping is done
automatically by hardware that supports the feature.

A pass is added which is intended to be run at the very end of the
pipeline to avoid any optimizations that would assume the prologue is a
real predecessor block to the actual code start. In reality we have two
possible entry points for the function. 1. The optimized path that
supports kernarg preloading which begins at an offset of 256 bytes. 2.
The backwards compatible entry point which starts at offset 0.



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