[PATCH] D157504: AMDGPU: Check for implicit defs before constant folding instruction

[Matt Arsenault via Phabricator via llvm-commits]

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Can't delete the constant folded instruction if scc is used.

      

In the original testcase, an un-constant folded and made it all the
way to SIFoldOperands. I think this is because a urem with known
bounds emitted during memcpy lowering wasn't appropriately simplified
since it was emitted so late. We should probably try to avoid that in
the first place.

Many GlobalISel tests show regressions for two reasons. First, it's
not setting dead flags in some cases. The reason we care about the
dead flags is compensating for failure to constant fold common
operations in the first place.

Fixes #63986


https://reviews.llvm.org/D157504

Files:
  llvm/include/llvm/CodeGen/MachineInstr.h
  llvm/lib/CodeGen/MachineInstr.cpp
  llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
  llvm/test/CodeGen/AMDGPU/GlobalISel/fshl.ll
  llvm/test/CodeGen/AMDGPU/GlobalISel/fshr.ll
  llvm/test/CodeGen/AMDGPU/GlobalISel/llvm.abs.ll
  llvm/test/CodeGen/AMDGPU/GlobalISel/llvm.amdgcn.intersect_ray.ll
  llvm/test/CodeGen/AMDGPU/GlobalISel/llvm.amdgcn.wqm.demote.ll
  llvm/test/CodeGen/AMDGPU/GlobalISel/saddsat.ll
  llvm/test/CodeGen/AMDGPU/GlobalISel/sext_inreg.ll
  llvm/test/CodeGen/AMDGPU/GlobalISel/shl.ll
  llvm/test/CodeGen/AMDGPU/GlobalISel/ssubsat.ll
  llvm/test/CodeGen/AMDGPU/GlobalISel/store-local.128.ll
  llvm/test/CodeGen/AMDGPU/GlobalISel/store-local.96.ll
  llvm/test/CodeGen/AMDGPU/GlobalISel/uaddsat.ll
  llvm/test/CodeGen/AMDGPU/GlobalISel/usubsat.ll
  llvm/test/CodeGen/AMDGPU/constant-fold-imm-immreg.mir
  llvm/test/CodeGen/AMDGPU/mad-mix-hi.ll
  llvm/test/CodeGen/AMDGPU/memcpy-crash-issue63986.ll

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