[PATCH] D148713: [LegalizeTypes][VP] Widen load/store of fixed length vectors to VP ops

[Luke Lau via Phabricator via llvm-commits]

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If we have a load/store with an illegal fixed length vector result type that
needs widened, e.g. `x:v6i32 = load p`
Instead of just widening it to: `x:v8i32 = load p`
We can widen it to the equivalent VP operation and set the EVL to the
exact number of elements needed: `x:v8i32 = vp_load a, b, mask=true, evl=6`
Provided that the target supports vp_load/vp_store on the widened type.

Scalable vectors are already widened this way where possible, so this
largely reuses the same logic.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D148713

Files:
  llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
  llvm/test/CodeGen/RISCV/rvv/fixed-vectors-abs.ll
  llvm/test/CodeGen/RISCV/rvv/fixed-vectors-extract.ll
  llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fp.ll
  llvm/test/CodeGen/RISCV/rvv/fixed-vectors-fp2i.ll
  llvm/test/CodeGen/RISCV/rvv/fixed-vectors-i2fp.ll
  llvm/test/CodeGen/RISCV/rvv/fixed-vectors-insert.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-interleaved-access.ll
  llvm/test/CodeGen/RISCV/rvv/fixed-vectors-load.ll
  llvm/test/CodeGen/RISCV/rvv/fixed-vectors-store.ll
  llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vselect.ll

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