[all-commits] [llvm/llvm-project] 40d952: [CGP] Avoid replacing a free ext with multiple oth...

[Florian Hahn via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 40d952b8748bf5c4a97fc82296e1fc050388472f
      https://github.com/llvm/llvm-project/commit/40d952b8748bf5c4a97fc82296e1fc050388472f
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2024-01-18 (Thu, 18 Jan 2024)

  Changed paths:
    M llvm/lib/CodeGen/CodeGenPrepare.cpp
    M llvm/test/CodeGen/AArch64/arm64-codegen-prepare-extload.ll
    M llvm/test/CodeGen/AArch64/avoid-free-ext-promotion.ll
    M llvm/test/CodeGen/AArch64/bfis-in-loop.ll
    M llvm/test/CodeGen/X86/inline-spiller-impdef-on-implicit-def-regression.ll

  Log Message:
  -----------
  [CGP] Avoid replacing a free ext with multiple other exts. (#77094)

Replacing a free extension with 2 or more extensions unnecessarily
increases the number of IR instructions without providing any benefits.
It also unnecessarily causes operations to be performed on wider types
than necessary.

In some cases, the extra extensions also pessimize codegen (see
bfis-in-loop.ll).

The changes in arm64-codegen-prepare-extload.ll also show that we avoid
promotions that should only be performed in stress mode.

PR: https://github.com/llvm/llvm-project/pull/77094