[all-commits] [llvm/llvm-project] 745e1e: [CodeGen] Ignore requiresStructuredCFG check in ca...

[Wenju He via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 745e1e6ad5d40ff8f1553e62c48554a61611ee76
      https://github.com/llvm/llvm-project/commit/745e1e6ad5d40ff8f1553e62c48554a61611ee76
  Author: Wenju He <wenju.he at intel.com>
  Date:   2025-09-26 (Fri, 26 Sep 2025)

  Changed paths:
    M llvm/include/llvm/CodeGen/MachineBasicBlock.h
    M llvm/lib/CodeGen/MachineBasicBlock.cpp
    A llvm/test/CodeGen/NVPTX/machinelicm-no-preheader.mir

  Log Message:
  -----------
  [CodeGen] Ignore requiresStructuredCFG check in canSplitCriticalEdge if successor is loop header (#154063)

This addresses a performance issue for our downstream GPU target that
sets requiresStructuredCFG to true. The issue is that EarlyMachineLICM
pass does not hoist loop invariants because a critical edge is not
split.
The critical edge's destination a loop header. Splitting the critical
edge will not break structured CFG.

Add a nvptx test to demonstrate the issue since the target also
requires structured CFG.

---------

Co-authored-by: Matt Arsenault <arsenm2 at gmail.com>



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