[PATCH] D97325: [LegalizeIntegerTypes] Further improve ExpandIntRes_SADDSUBO for targets where SADDO/SSUBO aren't supported.

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: RKSimon, spatel, rogfer01, luismarques.
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Rather than converting 3 signbits to bools and comparing them,
we can do bitwise logic on the whole vector and convert the
resulting sign bit to a bool at the end.

This is still a different algorithm than what we do in LegalizeDAG
through expandSADDOSSUBO. That algorithm needs to know that the
RHS of SSUBO is > 0, but that's costly when the type is split.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D97325

Files:
  llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
  llvm/test/CodeGen/AArch64/sadd_sat_vec.ll
  llvm/test/CodeGen/AArch64/ssub_sat_vec.ll
  llvm/test/CodeGen/ARM/sadd_sat.ll
  llvm/test/CodeGen/ARM/sadd_sat_plus.ll
  llvm/test/CodeGen/ARM/ssub_sat.ll
  llvm/test/CodeGen/ARM/ssub_sat_plus.ll
  llvm/test/CodeGen/RISCV/sadd_sat.ll
  llvm/test/CodeGen/RISCV/sadd_sat_plus.ll
  llvm/test/CodeGen/RISCV/ssub_sat.ll
  llvm/test/CodeGen/RISCV/ssub_sat_plus.ll
  llvm/test/CodeGen/RISCV/xaluo.ll
  llvm/test/CodeGen/Thumb2/mve-saturating-arith.ll

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