[all-commits] [llvm/llvm-project] 1cea4a: [AMDGPU][NPM] Fix CFG invalidation detection in in...

[Prasoon Mishra via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 1cea4a0841dacefa49241538a55fbf4f34462633
      https://github.com/llvm/llvm-project/commit/1cea4a0841dacefa49241538a55fbf4f34462633
  Author: Prasoon Mishra <Prasoon.Mishra at amd.com>
  Date:   2025-11-28 (Fri, 28 Nov 2025)

  Changed paths:
    M llvm/lib/Target/AMDGPU/SIInstrInfo.cpp

  Log Message:
  -----------
  [AMDGPU][NPM] Fix CFG invalidation detection in insertSimulatedTrap (#169290)

When SIMULATED_TRAP is at the end of a block with no successors,
insertSimulatedTrap incorrectly returns the original MBB despite adding
HaltLoopBB to the CFG.

EmitInstrWithCustomInserter detects CFG changes by comparing the
returned MBB with the original. When they match, it assumes no
modification occurred and skips MachineLoopInfo invalidation. This
causes stale loop information in subsequent passes, particularly when
using the NPM which relies on accurate invalidation signals.

Fix: Return HaltLoopBB to properly signal the CFG modification.



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