[PATCH] D120234: [ARM] Make i32 ISD::ABS Legal instead of pattern matching during isel.
Craig Topper via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Sun Feb 20 23:59:54 PST 2022
craig.topper created this revision.
craig.topper added reviewers: dmgreen, RKSimon.
Herald added subscribers: steven.zhang, hiraditya, kristof.beyls.
craig.topper requested review of this revision.
Herald added a project: LLVM.
Instead of matching (sra (X, size(X)-1); sub (xor (X, Y), Y))
during isel, make ISD::ABS Legal and use a regular isel pattern.
Also add new pseudo instructions for NABS to avoid creating a negate
after the ABS pseudo expansion. NABS is no longer expanded by DAGCombiner
to (sra (X, size(X)-1); sub (Y, xor (X, Y)) due to ABS being legal.
The new codegen looks like what gcc generates for NABS.
This is a followup from D119171 <https://reviews.llvm.org/D119171>.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D120234
Files:
llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
llvm/lib/Target/ARM/ARMISelLowering.cpp
llvm/lib/Target/ARM/ARMInstrInfo.td
llvm/lib/Target/ARM/ARMInstrThumb2.td
llvm/test/CodeGen/ARM/iabs.ll
llvm/test/CodeGen/Thumb2/abs.ll
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