[all-commits] [llvm/llvm-project] b88178: Support critical edge splitting for jump tables

[Matthias Braun via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: b8817825b9dcb45f204d3a3a9056f929e12c7a3b
      https://github.com/llvm/llvm-project/commit/b8817825b9dcb45f204d3a3a9056f929e12c7a3b
  Author: Matthias Braun <matze at braunis.de>
  Date:   2023-05-10 (Wed, 10 May 2023)

  Changed paths:
    M llvm/include/llvm/CodeGen/TargetInstrInfo.h
    M llvm/lib/CodeGen/MachineBasicBlock.cpp
    M llvm/lib/Target/X86/X86InstrInfo.cpp
    M llvm/lib/Target/X86/X86InstrInfo.h
    A llvm/test/CodeGen/X86/switch-jmp-edge-split.mir
    M llvm/test/CodeGen/X86/switch-phi-const.ll

  Log Message:
  -----------
  Support critical edge splitting for jump tables

Add support for splitting critical edges coming from an indirect jump
using a jump table ("switch jumps").

This introduces the `TargetInstrInfo::getJumpTableIndex` callback to
allows targets to return an index into `MachineJumpTableInfo` for a
given indirect jump. It also updates to
`MachineBasicBlock::SplitCriticalEdge` to allow splitting of critical
edges by rewriting jump table entries.

This is largely based on work done by Zhixuan Huan in D132202.

Differential Revision: https://reviews.llvm.org/D140975