[PATCH] D95741: [RISCV] Optimize sign-extended EXTRACT_VECTOR_ELT nodes

[Fraser Cormack via Phabricator via llvm-commits]

frasercrmck created this revision.
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This patch custom-legalizes all integer EXTRACT_VECTOR_ELT nodes where
SEW < XLEN to VMV_S_X nodes to help the compiler infer sign bits from
the result. This allows us to eliminate redundant sign extensions.

For parity, all integer EXTRACT_VECTOR_ELT nodes are legalized this way
so that we don't need TableGen patterns for some and not others.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D95741

Files:
  llvm/lib/Target/RISCV/RISCVISelLowering.cpp
  llvm/lib/Target/RISCV/RISCVISelLowering.h
  llvm/lib/Target/RISCV/RISCVInstrInfoVSDPatterns.td
  llvm/test/CodeGen/RISCV/rvv/extractelt-int-rv32.ll
  llvm/test/CodeGen/RISCV/rvv/extractelt-int-rv64.ll

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