[llvm] AMDGPU: Use LiveIntervals instead of LiveVariables in SIOptimizeVGPRLiveRange (PR #227252)

[Christudasan Devadasan via llvm-commits]

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@@ -686,33 +512,28 @@ bool SIOptimizeVGPRLiveRangeLegacy::runOnMachineFunction(MachineFunction &MF) {
   if (skipFunction(MF.getFunction()))
     return false;
 
-  auto *LISWrapper = getAnalysisIfAvailable<LiveIntervalsWrapperPass>();
-  LiveIntervals *LIS = LISWrapper ? &LISWrapper->getLIS() : nullptr;
-  LiveVariables *LV = &getAnalysis<LiveVariablesWrapperPass>().getLV();
+  LiveIntervals *LIS = &getAnalysis<LiveIntervalsWrapperPass>().getLIS();
   MachineDominatorTree *MDT =
       &getAnalysis<MachineDominatorTreeWrapperPass>().getDomTree();
   MachineLoopInfo *Loops = &getAnalysis<MachineLoopInfoWrapperPass>().getLI();
-  return SIOptimizeVGPRLiveRange(LIS, LV, MDT, Loops).run(MF);
+  return SIOptimizeVGPRLiveRange(LIS, MDT, Loops).run(MF);
 }
 
 PreservedAnalyses
 SIOptimizeVGPRLiveRangePass::run(MachineFunction &MF,
                                  MachineFunctionAnalysisManager &MFAM) {
   MFPropsModifier _(*this, MF);
-  LiveIntervals *LIS = MFAM.getCachedResult<LiveIntervalsAnalysis>(MF);
-  LiveVariables *LV = MFAM.getCachedResult<LiveVariablesAnalysis>(MF);
-  if (!LIS && !LV)
-    LV = &MFAM.getResult<LiveVariablesAnalysis>(MF);
+  LiveIntervals *LIS = &MFAM.getResult<LiveIntervalsAnalysis>(MF);
   MachineDominatorTree *MDT = &MFAM.getResult<MachineDominatorTreeAnalysis>(MF);
   MachineLoopInfo *Loops = &MFAM.getResult<MachineLoopAnalysis>(MF);
 
-  bool Changed = SIOptimizeVGPRLiveRange(LIS, LV, MDT, Loops).run(MF);
+  bool Changed = SIOptimizeVGPRLiveRange(LIS, MDT, Loops).run(MF);
   if (!Changed)
     return PreservedAnalyses::all();
 
   auto PA = getMachineFunctionPassPreservedAnalyses();
+  PA.preserve<SlotIndexesAnalysis>();
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cdevadas wrote:

I was expecting the pass manager to resolve such dependencies. They are statically known anyway.

https://github.com/llvm/llvm-project/pull/227252