[all-commits] [llvm/llvm-project] c9df11: AMDGPU: Use LiveIntervals instead of LiveVariables...

[Matt Arsenault via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: c9df11991d971c1bf16e58fd4b5350c0865ba616
      https://github.com/llvm/llvm-project/commit/c9df11991d971c1bf16e58fd4b5350c0865ba616
  Author: Matt Arsenault <Matthew.Arsenault at amd.com>
  Date:   2026-09-30 (Wed, 30 Sep 2026)

  Changed paths:
    M llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp
    M llvm/lib/Target/AMDGPU/SIOptimizeVGPRLiveRange.cpp
    M llvm/test/CodeGen/AMDGPU/GlobalISel/divergence-divergent-i1-used-outside-loop.ll
    M llvm/test/CodeGen/AMDGPU/GlobalISel/divergence-structurizer.ll
    M llvm/test/CodeGen/AMDGPU/GlobalISel/vni8-across-blocks.ll
    M llvm/test/CodeGen/AMDGPU/a-v-flat-atomic-cmpxchg.ll
    M llvm/test/CodeGen/AMDGPU/a-v-flat-atomicrmw.ll
    M llvm/test/CodeGen/AMDGPU/absdiff.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.1024bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.128bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.256bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.320bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.32bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.48bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.512bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.640bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.64bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.704bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.768bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.832bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.896bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.960bit.ll
    M llvm/test/CodeGen/AMDGPU/amdgcn.bitcast.96bit.ll
    M llvm/test/CodeGen/AMDGPU/asyncmark-gfx12plus.ll
    M llvm/test/CodeGen/AMDGPU/asyncmark-pregfx12.ll
    M llvm/test/CodeGen/AMDGPU/atomicrmw-nand.ll
    M llvm/test/CodeGen/AMDGPU/block-should-not-be-in-alive-blocks.mir
    M llvm/test/CodeGen/AMDGPU/branch-folding-implicit-def-subreg.ll
    M llvm/test/CodeGen/AMDGPU/branch-relaxation-gfx1250.ll
    M llvm/test/CodeGen/AMDGPU/bypass-div.ll
    M llvm/test/CodeGen/AMDGPU/div_i128.ll
    M llvm/test/CodeGen/AMDGPU/div_v2i128.ll
    M llvm/test/CodeGen/AMDGPU/flat_atomics_i64_noprivate.ll
    M llvm/test/CodeGen/AMDGPU/flat_atomics_i64_system.ll
    M llvm/test/CodeGen/AMDGPU/fptoi.i128.ll
    M llvm/test/CodeGen/AMDGPU/fract-match.ll
    M llvm/test/CodeGen/AMDGPU/frem.ll
    M llvm/test/CodeGen/AMDGPU/global_atomics_scan_fmax.ll
    M llvm/test/CodeGen/AMDGPU/global_atomics_scan_fmin.ll
    M llvm/test/CodeGen/AMDGPU/llc-pipeline-npm.ll
    M llvm/test/CodeGen/AMDGPU/llc-pipeline.ll
    M llvm/test/CodeGen/AMDGPU/llvm.amdgcn.init.whole.wave-w32.ll
    M llvm/test/CodeGen/AMDGPU/llvm.amdgcn.reduce.fadd.ll
    M llvm/test/CodeGen/AMDGPU/llvm.amdgcn.reduce.fsub.ll
    M llvm/test/CodeGen/AMDGPU/local-atomicrmw-fadd.ll
    M llvm/test/CodeGen/AMDGPU/local-atomicrmw-fmax.ll
    M llvm/test/CodeGen/AMDGPU/local-atomicrmw-fmin.ll
    M llvm/test/CodeGen/AMDGPU/local-atomicrmw-fsub.ll
    M llvm/test/CodeGen/AMDGPU/lower-control-flow-live-variables-update.mir
    R llvm/test/CodeGen/AMDGPU/lower-control-flow-live-variables-update.xfail.mir
    M llvm/test/CodeGen/AMDGPU/mad_uint24.ll
    M llvm/test/CodeGen/AMDGPU/rewrite-vgpr-mfma-to-agpr-spill-multi-store-codegen.ll
    M llvm/test/CodeGen/AMDGPU/si-opt-vgpr-liverange-bug-deadlanes.mir
    R llvm/test/CodeGen/AMDGPU/si-opt-vgpr-liverange-undef-use-livevars.mir
    A llvm/test/CodeGen/AMDGPU/si-opt-vgpr-liverange-undef-use.mir
    M llvm/test/CodeGen/AMDGPU/si-optimize-vgpr-live-range-dbg-instr.mir
    M llvm/test/CodeGen/AMDGPU/splitkit-getsubrangeformask-phi-extend.ll
    M llvm/test/CodeGen/AMDGPU/srem64.ll
    M llvm/test/CodeGen/AMDGPU/urem64.ll
    M llvm/test/CodeGen/AMDGPU/vgpr-liverange-ir.ll
    M llvm/test/CodeGen/AMDGPU/vni8-across-blocks.ll

  Log Message:
  -----------
  AMDGPU: Use LiveIntervals instead of LiveVariables in SIOptimizeVGPRLiveRange (#227252)

Drop the LiveVariables dependency and only use LiveIntervals.

The legacy pass manager cannot schedule a pass requiring both
LiveIntervals and LiveVariables here, since LiveVariables (and its
UnreachableMachineBlockElim dependency) invalidates the LiveIntervals
just computed for it. In the AMDGPU pipeline, anchor the pass after
MachineLoopInfo instead of PHIElimination so LiveIntervals is computed
before PHIElimination, which is required anyway: the pass needs SSA and
introduces new PHIs. Preserving SlotIndexes keeps the transitive last-user 
chain intact.

Since LiveVariables is no longer maintained past this point, PHIElimination
now splits critical edges using LiveIntervals, which accounts for most
of the test churn: LiveIntervalCalc drops kill flags and adds dead flags.

Co-authored-by: Claude Opus 5 <noreply at anthropic.com>



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