[LCSSA] Use IRBuilder for PHI creation.

Use IRBuilder instead PHINode::Create. This should not impact the
generated code, but IRBuilder provides a way to register callbacks for
inserted instructions, which is convenient for some users.

Reviewed By: lebedev.ri

Differential Revision: https://reviews.llvm.org/D85037

1 files changed, 11 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/Utils/LCSSA.cpp b/llvm/lib/Transforms/Utils/LCSSA.cpp
index b1a1c56..9c60625 100644
--- a/llvm/lib/Transforms/Utils/LCSSA.cpp
+++ b/llvm/lib/Transforms/Utils/LCSSA.cpp
@@ -40,6 +40,7 @@
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/IR/Function.h"
+#include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/PredIteratorCache.h"
@@ -77,12 +78,15 @@ static bool isExitBlock(BasicBlock *BB,
 /// rewrite the uses.
 bool llvm::formLCSSAForInstructions(SmallVectorImpl<Instruction *> &Worklist,
                                     const DominatorTree &DT, const LoopInfo &LI,
-                                    ScalarEvolution *SE) {
+                                    ScalarEvolution *SE,
+                                    IRBuilderBase &Builder) {
   SmallVector<Use *, 16> UsesToRewrite;
   SmallSetVector<PHINode *, 16> PHIsToRemove;
   PredIteratorCache PredCache;
   bool Changed = false;
 
+  IRBuilderBase::InsertPointGuard InsertPtGuard(Builder);
+
   // Cache the Loop ExitBlocks across this loop.  We expect to get a lot of
   // instructions within the same loops, computing the exit blocks is
   // expensive, and we're not mutating the loop structure.
@@ -151,9 +155,9 @@ bool llvm::formLCSSAForInstructions(SmallVectorImpl<Instruction *> &Worklist,
       // If we already inserted something for this BB, don't reprocess it.
       if (SSAUpdate.HasValueForBlock(ExitBB))
         continue;
-
-      PHINode *PN = PHINode::Create(I->getType(), PredCache.size(ExitBB),
-                                    I->getName() + ".lcssa", &ExitBB->front());
+      Builder.SetInsertPoint(&ExitBB->front());
+      PHINode *PN = Builder.CreatePHI(I->getType(), PredCache.size(ExitBB),
+                                      I->getName() + ".lcssa");
       // Get the debug location from the original instruction.
       PN->setDebugLoc(I->getDebugLoc());
       // Add inputs from inside the loop for this PHI.
@@ -369,7 +373,9 @@ bool llvm::formLCSSA(Loop &L, const DominatorTree &DT, const LoopInfo *LI,
       Worklist.push_back(&I);
     }
   }
-  Changed = formLCSSAForInstructions(Worklist, DT, *LI, SE);
+
+  IRBuilder<> Builder(L.getHeader()->getContext());
+  Changed = formLCSSAForInstructions(Worklist, DT, *LI, SE, Builder);
 
   // If we modified the code, remove any caches about the loop from SCEV to
   // avoid dangling entries.