[llvm] 92bf8f3 - [NFC][SimplifyCFG] `shouldFoldCondBranchesToCommonDestination()`: report the common succ

[Roman Lebedev via llvm-commits]

Author: Roman Lebedev
Date: 2022-12-04T20:58:54+03:00
New Revision: 92bf8f3f79639f37724b0f68a3c21d8bb3c9a972

URL: https://github.com/llvm/llvm-project/commit/92bf8f3f79639f37724b0f68a3c21d8bb3c9a972
DIFF: https://github.com/llvm/llvm-project/commit/92bf8f3f79639f37724b0f68a3c21d8bb3c9a972.diff

LOG: [NFC][SimplifyCFG] `shouldFoldCondBranchesToCommonDestination()`: report the common succ

Added: 
    

Modified: 
    llvm/lib/Transforms/Utils/SimplifyCFG.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 6cdd18fe9041..a1bc89e7d809 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -3521,7 +3521,7 @@ static bool extractPredSuccWeights(BranchInst *PBI, BranchInst *BI,
 /// Determine if the two branches share a common destination and deduce a glue
 /// that joins the branches' conditions to arrive at the common destination if
 /// that would be profitable.
-static std::optional<std::pair<Instruction::BinaryOps, bool>>
+static std::optional<std::tuple<BasicBlock *, Instruction::BinaryOps, bool>>
 shouldFoldCondBranchesToCommonDestination(BranchInst *BI, BranchInst *PBI,
                                           const TargetTransformInfo *TTI) {
   assert(BI && PBI && BI->isConditional() && PBI->isConditional() &&
@@ -3544,19 +3544,19 @@ shouldFoldCondBranchesToCommonDestination(BranchInst *BI, BranchInst *PBI,
   if (PBI->getSuccessor(0) == BI->getSuccessor(0)) {
     // Speculate the 2nd condition unless the 1st is probably true.
     if (PBITrueProb.isUnknown() || PBITrueProb < Likely)
-      return {{Instruction::Or, false}};
+      return {{BI->getSuccessor(0), Instruction::Or, false}};
   } else if (PBI->getSuccessor(1) == BI->getSuccessor(1)) {
     // Speculate the 2nd condition unless the 1st is probably false.
     if (PBITrueProb.isUnknown() || PBITrueProb.getCompl() < Likely)
-      return {{Instruction::And, false}};
+      return {{BI->getSuccessor(1), Instruction::And, false}};
   } else if (PBI->getSuccessor(0) == BI->getSuccessor(1)) {
     // Speculate the 2nd condition unless the 1st is probably true.
     if (PBITrueProb.isUnknown() || PBITrueProb < Likely)
-      return {{Instruction::And, true}};
+      return {{BI->getSuccessor(1), Instruction::And, true}};
   } else if (PBI->getSuccessor(1) == BI->getSuccessor(0)) {
     // Speculate the 2nd condition unless the 1st is probably false.
     if (PBITrueProb.isUnknown() || PBITrueProb.getCompl() < Likely)
-      return {{Instruction::Or, true}};
+      return {{BI->getSuccessor(0), Instruction::Or, true}};
   }
   return std::nullopt;
 }
@@ -3569,9 +3569,10 @@ static bool performBranchToCommonDestFolding(BranchInst *BI, BranchInst *PBI,
   BasicBlock *PredBlock = PBI->getParent();
 
   // Determine if the two branches share a common destination.
+  BasicBlock *CommonSucc;
   Instruction::BinaryOps Opc;
   bool InvertPredCond;
-  std::tie(Opc, InvertPredCond) =
+  std::tie(CommonSucc, Opc, InvertPredCond) =
       *shouldFoldCondBranchesToCommonDestination(BI, PBI, TTI);
 
   LLVM_DEBUG(dbgs() << "FOLDING BRANCH TO COMMON DEST:\n" << *PBI << *BB);
@@ -3730,10 +3731,11 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI, DomTreeUpdater *DTU,
       continue;
 
     // Determine if the two branches share a common destination.
+    BasicBlock *CommonSucc;
     Instruction::BinaryOps Opc;
     bool InvertPredCond;
     if (auto Recipe = shouldFoldCondBranchesToCommonDestination(BI, PBI, TTI))
-      std::tie(Opc, InvertPredCond) = *Recipe;
+      std::tie(CommonSucc, Opc, InvertPredCond) = *Recipe;
     else
       continue;