[PATCH] D85207: Fix 64-bit copy to SCC

[Piotr Sobczak via Phabricator via llvm-commits]

piotr created this revision.
Herald added subscribers: llvm-commits, kerbowa, hiraditya, nhaehnle, jvesely, arsenm.
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Fix 64-bit copy to SCC by restricting the pattern resulting
in such a copy to subtargets supporting 64-bit scalar compare,
and mapping the copy to S_CMP_LG_U64.

Before introducing the S_CSELECT pattern with explicit SCC
(0045786f146e78afee49eee053dc29ebc842fee1 <https://reviews.llvm.org/rG0045786f146e78afee49eee053dc29ebc842fee1>), there was no need
for handling 64-bit copy to SCC ($scc = COPY sreg_64).

The proposed handling to read only the low bits was however
based on a false premise that it is only one bit that matters,
while in fact the copy source might be a vector of booleans and
all bits need to be considered.

The practical problem of mapping the 64-bit copy to SCC is that
the natural instruction to use (S_CMP_LG_U64) is not available
on old hardware. Fix it by restricting the problematic pattern
to subtargets supporting the instruction (hasScalarCompareEq64).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D85207

Files:
  llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
  llvm/lib/Target/AMDGPU/SOPInstructions.td
  llvm/test/CodeGen/AMDGPU/32-bit-local-address-space.ll
  llvm/test/CodeGen/AMDGPU/addrspacecast.ll
  llvm/test/CodeGen/AMDGPU/amdgpu-codegenprepare-idiv.ll
  llvm/test/CodeGen/AMDGPU/ctlz.ll
  llvm/test/CodeGen/AMDGPU/ctlz_zero_undef.ll
  llvm/test/CodeGen/AMDGPU/extractelt-to-trunc.ll
  llvm/test/CodeGen/AMDGPU/fceil64.ll
  llvm/test/CodeGen/AMDGPU/fshl.ll
  llvm/test/CodeGen/AMDGPU/fshr.ll
  llvm/test/CodeGen/AMDGPU/insert_vector_elt.ll
  llvm/test/CodeGen/AMDGPU/mad_uint24.ll
  llvm/test/CodeGen/AMDGPU/sad.ll
  llvm/test/CodeGen/AMDGPU/sdiv.ll
  llvm/test/CodeGen/AMDGPU/sdiv64.ll
  llvm/test/CodeGen/AMDGPU/select-opt.ll
  llvm/test/CodeGen/AMDGPU/select-vectors.ll
  llvm/test/CodeGen/AMDGPU/select64.ll
  llvm/test/CodeGen/AMDGPU/sint_to_fp.f64.ll
  llvm/test/CodeGen/AMDGPU/srem64.ll
  llvm/test/CodeGen/AMDGPU/trunc.ll
  llvm/test/CodeGen/AMDGPU/udiv64.ll
  llvm/test/CodeGen/AMDGPU/udivrem.ll
  llvm/test/CodeGen/AMDGPU/uint_to_fp.f64.ll
  llvm/test/CodeGen/AMDGPU/urem64.ll
  llvm/test/CodeGen/AMDGPU/vselect.ll

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