[PATCH] D127520: [RISCV] Move creation of constant pools from isel to lowering.

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: asb, luismarques, jrtc27, reames.
Herald added subscribers: sunshaoce, VincentWu, luke957, StephenFan, vkmr, frasercrmck, evandro, apazos, sameer.abuasal, steven.zhang, s.egerton, Jim, benna, psnobl, jocewei, PkmX, the_o, brucehoult, MartinMosbeck, rogfer01, edward-jones, zzheng, shiva0217, kito-cheng, niosHD, sabuasal, simoncook, johnrusso, rbar, hiraditya, arichardson.
Herald added a project: All.
craig.topper requested review of this revision.
Herald added subscribers: pcwang-thead, eopXD, MaskRay.
Herald added a project: LLVM.

This simplifies the isel code by removing the manual load creation.
It also improves our ability to use 0 strided loads for vector splats.

There is an assumption here that Mask and ShiftedMask constants are
cheap enough that they don't become constant pool loads so that our
isel optimizations involving And still work. I believe those constants
are 3 instructions in the worst case.

The rv64zbp-intrinsic.ll changes is a regression caused by intrinsics
being expanded to RISCVISD also occuring during lowering. So the optimizations
were only happening during the last DAGCombine, which can't see through the
load. I believe we can fix this test by implementing
TargetLowering::getTargetConstantFromLoad for RISC-V or by adding the intrinsic
to computeKnownBitsForTargetNode to enable earlier DAG combine. Since Zbp is not
a ratified extension, I don't view these as blocking this patch.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D127520

Files:
  llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
  llvm/lib/Target/RISCV/RISCVISelLowering.cpp
  llvm/test/CodeGen/RISCV/rv64zbp-intrinsic.ll
  llvm/test/CodeGen/RISCV/rv64zbp.ll
  llvm/test/CodeGen/RISCV/rvv/fixed-vectors-int-buildvec.ll
  llvm/test/CodeGen/RISCV/rvv/fixed-vectors-int.ll
  llvm/test/CodeGen/RISCV/rvv/fixed-vectors-mask-buildvec.ll

-------------- next part --------------
A non-text attachment was scrubbed...
Name: D127520.435992.patch
Type: text/x-patch
Size: 16081 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20220610/2bd9755b/attachment.bin>