[all-commits] [llvm/llvm-project] ab39c4: [X86][APX] Reuse EFLAGS across multi-predecessor b...

[Feng Zou via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: ab39c491430e1f327849708ababffa3458b8ff6f
      https://github.com/llvm/llvm-project/commit/ab39c491430e1f327849708ababffa3458b8ff6f
  Author: Feng Zou <feng.zou at intel.com>
  Date:   2026-07-19 (Sun, 19 Jul 2026)

  Changed paths:
    M llvm/lib/Target/X86/X86FlagsCopyLowering.cpp
    M llvm/lib/Target/X86/X86InstrInfo.cpp
    M llvm/lib/Target/X86/X86InstrInfo.h
    M llvm/test/CodeGen/X86/apx/add.ll
    M llvm/test/CodeGen/X86/apx/flags-copy-lowering.ll
    A llvm/test/CodeGen/X86/apx/optimize-compare-multipred.ll
    A llvm/test/CodeGen/X86/apx/optimize-compare-multipred.mir

  Log Message:
  -----------
  [X86][APX] Reuse EFLAGS across multi-predecessor blocks via NF in optimizeCompareInstr (#208184)

Extend optimizeCompareInstr to reuse EFLAGS produced in predecessor
blocks (including via NF variants) when a compare is redundant, covering
multi-predecessor, dominating, and cyclic CFGs. Share the NF-clobber
removal helper with FlagsCopyLowering, correctly handle swapped and
immediate-adjusted flag reuse, and simplify EFLAGS live-in marking.

Adds MIR tests exercising multi-predecessor reuse over cyclic and
dominating CFGs, including a multi-level idom walk.

Assisted-By: Claude Opus 4.8



To unsubscribe from these emails, change your notification settings at https://github.com/llvm/llvm-project/settings/notifications