[PATCH] D124439: [JumpThreading][NFC] Reuse existing LoopInfo instead of recomputation

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev created this revision.
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There is no need to recompute DT and LI from scratch when we can reuse
existing analyzes results. CompileTime saving happens because:

- DT is always available at this point;
- LI might be available from prior loop passes.


https://reviews.llvm.org/D124439

Files:
  llvm/lib/Transforms/Scalar/JumpThreading.cpp


Index: llvm/lib/Transforms/Scalar/JumpThreading.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -324,9 +324,9 @@
   std::unique_ptr<BlockFrequencyInfo> BFI;
   std::unique_ptr<BranchProbabilityInfo> BPI;
   if (F.hasProfileData()) {
-    LoopInfo LI{DominatorTree(F)};
-    BPI.reset(new BranchProbabilityInfo(F, LI, TLI));
-    BFI.reset(new BlockFrequencyInfo(F, *BPI, LI));
+    auto LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
+    BPI.reset(new BranchProbabilityInfo(F, *LI, TLI));
+    BFI.reset(new BlockFrequencyInfo(F, *BPI, *LI));
   }
 
   bool Changed = Impl.runImpl(F, TLI, TTI, LVI, AA, &DTU, F.hasProfileData(),
@@ -353,7 +353,7 @@
   std::unique_ptr<BlockFrequencyInfo> BFI;
   std::unique_ptr<BranchProbabilityInfo> BPI;
   if (F.hasProfileData()) {
-    LoopInfo LI{DominatorTree(F)};
+    auto &LI = AM.getResult<LoopAnalysis>(F);
     BPI.reset(new BranchProbabilityInfo(F, LI, &TLI));
     BFI.reset(new BlockFrequencyInfo(F, *BPI, LI));
   }


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