[PATCH] D106256: [LoopFlatten][LoopInfo] Use Loop to identify latch compare instruction

[Rosie Sumpter via Phabricator via llvm-commits]

RosieSumpter created this revision.
RosieSumpter added a reviewer: SjoerdMeijer.
Herald added a subscriber: hiraditya.
RosieSumpter requested review of this revision.
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Herald added a subscriber: llvm-commits.

Make getLatchCmpInst non-static and use it in LoopFlatten as a more
robust way of identifying the compare.


https://reviews.llvm.org/D106256

Files:
  llvm/include/llvm/Analysis/LoopInfo.h
  llvm/lib/Analysis/LoopInfo.cpp
  llvm/lib/Transforms/Scalar/LoopFlatten.cpp


Index: llvm/lib/Transforms/Scalar/LoopFlatten.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LoopFlatten.cpp
+++ llvm/lib/Transforms/Scalar/LoopFlatten.cpp
@@ -139,7 +139,7 @@
   };
 
   // Find Compare and make sure it is valid
-  ICmpInst *Compare = dyn_cast<ICmpInst>(BackBranch->getCondition());
+  ICmpInst *Compare = L->getLatchCmpInst();
   if (!Compare || !IsValidPredicate(Compare->getUnsignedPredicate()) ||
       Compare->hasNUsesOrMore(2)) {
     LLVM_DEBUG(dbgs() << "Could not find valid comparison\n");
Index: llvm/lib/Analysis/LoopInfo.cpp
===================================================================
--- llvm/lib/Analysis/LoopInfo.cpp
+++ llvm/lib/Analysis/LoopInfo.cpp
@@ -171,8 +171,8 @@
 }
 
 /// Get the latch condition instruction.
-static ICmpInst *getLatchCmpInst(const Loop &L) {
-  if (BasicBlock *Latch = L.getLoopLatch())
+ICmpInst *Loop::getLatchCmpInst() const {
+  if (BasicBlock *Latch = this->getLoopLatch())
     if (BranchInst *BI = dyn_cast_or_null<BranchInst>(Latch->getTerminator()))
       if (BI->isConditional())
         return dyn_cast<ICmpInst>(BI->getCondition());
@@ -183,7 +183,7 @@
 /// Return the final value of the loop induction variable if found.
 static Value *findFinalIVValue(const Loop &L, const PHINode &IndVar,
                                const Instruction &StepInst) {
-  ICmpInst *LatchCmpInst = getLatchCmpInst(L);
+  ICmpInst *LatchCmpInst = L.getLatchCmpInst();
   if (!LatchCmpInst)
     return nullptr;
 
@@ -297,7 +297,7 @@
 
   BasicBlock *Header = getHeader();
   assert(Header && "Expected a valid loop header");
-  ICmpInst *CmpInst = getLatchCmpInst(*this);
+  ICmpInst *CmpInst = this->getLatchCmpInst();
   if (!CmpInst)
     return nullptr;
 
Index: llvm/include/llvm/Analysis/LoopInfo.h
===================================================================
--- llvm/include/llvm/Analysis/LoopInfo.h
+++ llvm/include/llvm/Analysis/LoopInfo.h
@@ -589,6 +589,9 @@
   ///
   PHINode *getCanonicalInductionVariable() const;
 
+  /// Get the latch condition instruction.
+  ICmpInst *getLatchCmpInst() const;
+
   /// Obtain the unique incoming and back edge. Return false if they are
   /// non-unique or the loop is dead; otherwise, return true.
   bool getIncomingAndBackEdge(BasicBlock *&Incoming,


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