[PATCH] D108160: AMDGPU: Invert ABI attribute handling

[Matt Arsenault via Phabricator via llvm-commits]

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Previously we assumed all callable functions did not need any
implicitly passed inputs, and added attributes to functions to
indicate when they were necessary. Requiring attributes for
correctness is pretty ugly, and it makes supporting indirect and
external calls more complicated.

      

This inverts the direction of the attributes, so an undecorated
function is assumed to need all implicit imputs. This enables
AMDGPUAttributor by default to mark when functions are proven to not
need a given input. This strips the equivalent functionality from the
legacy AMDGPUAnnotateKernelFeatures pass.

      

However, AMDGPUAnnotateKernelFeatures is not fully removed at this
point although it should be in the future. It is still necessary for
the two hacky amdgpu-calls and amdgpu-stack-objects attributes, which
would be better served by a trivial analysis on the IR during
selection. Additionally, AMDGPUAnnotateKernelFeatures still
redundantly handles the uniform-work-group-size attribute to be
removed in a future commit.

      

At this point when not using -amdgpu-fixed-function-abi, we are still
modifying the ABI based on these newly negated attributes. In the
future, this option will be removed and the locations for implicit
inputs will always be fixed. We will then use the new attributes to
avoid passing the values when unnecessary.


https://reviews.llvm.org/D108160

Files:
  llvm/lib/Target/AMDGPU/AMDGPUAnnotateKernelFeatures.cpp
  llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp
  llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.cpp
  llvm/test/CodeGen/AMDGPU/addrspacecast-constantexpr.ll
  llvm/test/CodeGen/AMDGPU/annotate-kernel-features-hsa-call.ll
  llvm/test/CodeGen/AMDGPU/annotate-kernel-features-hsa.ll
  llvm/test/CodeGen/AMDGPU/annotate-kernel-features.ll
  llvm/test/CodeGen/AMDGPU/call-constexpr.ll
  llvm/test/CodeGen/AMDGPU/call-waitcnt.ll
  llvm/test/CodeGen/AMDGPU/callee-special-input-sgprs-fixed-abi.ll
  llvm/test/CodeGen/AMDGPU/callee-special-input-sgprs.ll
  llvm/test/CodeGen/AMDGPU/cc-update.ll
  llvm/test/CodeGen/AMDGPU/cross-block-use-is-not-abi-copy.ll
  llvm/test/CodeGen/AMDGPU/direct-indirect-call.ll
  llvm/test/CodeGen/AMDGPU/ds_read2.ll
  llvm/test/CodeGen/AMDGPU/duplicate-attribute-indirect.ll
  llvm/test/CodeGen/AMDGPU/flat-scratch-init.ll
  llvm/test/CodeGen/AMDGPU/indirect-call.ll
  llvm/test/CodeGen/AMDGPU/llc-pipeline.ll
  llvm/test/CodeGen/AMDGPU/llvm.amdgcn.implicitarg.ptr.ll
  llvm/test/CodeGen/AMDGPU/simple-indirect-call.ll
  llvm/test/CodeGen/AMDGPU/stack-pointer-offset-relative-frameindex.ll

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