[all-commits] [llvm/llvm-project] 6c59f3: [RISCV] Expand testing for store merging of multip...

[Philip Reames via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 6c59f399a6ca66b7ed3298ab5bcc594aa2930043
      https://github.com/llvm/llvm-project/commit/6c59f399a6ca66b7ed3298ab5bcc594aa2930043
  Author: Philip Reames <preames at rivosinc.com>
  Date:   2023-05-17 (Wed, 17 May 2023)

  Changed paths:
    M llvm/test/CodeGen/RISCV/rvv/combine-store.ll

  Log Message:
  -----------
  [RISCV] Expand testing for store merging of multiple constant stores


  Commit: 0457f506fddf47cfe842b398c7f522057cef8163
      https://github.com/llvm/llvm-project/commit/0457f506fddf47cfe842b398c7f522057cef8163
  Author: Philip Reames <preames at rivosinc.com>
  Date:   2023-05-17 (Wed, 17 May 2023)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVISelLowering.h
    M llvm/test/CodeGen/RISCV/rvv/combine-store.ll

  Log Message:
  -----------
  [RISCV] Implement storeOfVectorConstantIsCheap hook to prevent store merging at VL=2

In general, VL=2 vectors are very questionable profitability wise. For constants specifically, our inability to materialize many vector constants cheaply biases us strongly towards unprofitability at VL=2.

This hook is very close to the x86 implementation. The difference is that X86 whitelists stores of zeros, and we're better off letting that stay scalar at VL=2.

Differential Revision: https://reviews.llvm.org/D150798


Compare: https://github.com/llvm/llvm-project/compare/9c3299b85930...0457f506fddf