[all-commits] [llvm/llvm-project] 68079e: Teach SimplifyCFG to fold switches into lookup tab...

[Owen Anderson via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 68079ef0eb011c8349e5ae84b95216e5039dbc16
      https://github.com/llvm/llvm-project/commit/68079ef0eb011c8349e5ae84b95216e5039dbc16
  Author: Owen Anderson <resistor at mac.com>
  Date:   2021-09-15 (Wed, 15 Sep 2021)

  Changed paths:
    M llvm/lib/Transforms/Utils/SimplifyCFG.cpp
    A llvm/test/Transforms/SimplifyCFG/X86/switch-to-lookup-bitcast.ll
    A llvm/test/Transforms/SimplifyCFG/X86/switch-to-lookup-gep.ll

  Log Message:
  -----------
  Teach SimplifyCFG to fold switches into lookup tables in more cases.

In particular, it couldn't handle cases where lookup table constant
expressions involved bitcasts. This does not seem to come up
frequently in C++, but comes up reasonably often in Rust via
`#[derive(Debug)]`.

Originally reported by pcwalton.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D109565