[NFC] BasicBlock: refactor changePhiUses() out of replacePhiUsesWith(), use it

Summary:
It is a common thing to loop over every `PHINode` in some `BasicBlock`
and change old `BasicBlock` incoming block to a new `BasicBlock` incoming block.
`replaceSuccessorsPhiUsesWith()` already had code to do that,
it just wasn't a function.
So outline it into a new function, and use it.

Reviewers: chandlerc, craig.topper, spatel, danielcdh

Reviewed By: craig.topper

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61013

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@359996 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/BasicBlock.h

@@ -390,6 +390,10 @@ public:
   /// direct branches, switches, etc. to it.
   bool hasAddressTaken() const { return getSubclassDataFromValue() != 0; }
 
+  /// Update all phi nodes in this basic block to refer to basic block \p New
+  /// instead of basic block \p Old.
+  void replacePhiUsesWith(BasicBlock *Old, BasicBlock *New);
+
   /// Update all phi nodes in this basic block's successors to refer to basic
   /// block \p New instead of to it.
   void replaceSuccessorsPhiUsesWith(BasicBlock *New);

lib/CodeGen/CodeGenPrepare.cpp

@@ -7221,8 +7221,7 @@ bool CodeGenPrepare::splitBranchCondition(Function &F, bool &ModifiedDT) {
       std::swap(TBB, FBB);
 
     // Replace the old BB with the new BB.
-    for (PHINode &PN : TBB->phis())
-      PN.replaceIncomingBlockWith(&BB, TmpBB);
+    TBB->replacePhiUsesWith(&BB, TmpBB);
 
     // Add another incoming edge form the new BB.
     for (PHINode &PN : FBB->phis()) {

lib/IR/BasicBlock.cpp

@@ -427,32 +427,32 @@ BasicBlock *BasicBlock::splitBasicBlock(iterator I, const Twine &BBName) {
   // successors.  If there were PHI nodes in the successors, then they need to
   // know that incoming branches will be from New, not from Old.
   //
-  for (succ_iterator I = succ_begin(New), E = succ_end(New); I != E; ++I) {
-    // Loop over any phi nodes in the basic block, updating the BB field of
-    // incoming values...
-    BasicBlock *Successor = *I;
-    for (auto &PN : Successor->phis())
-      PN.replaceIncomingBlockWith(this, New);
-  }
+  llvm::for_each(successors(New), [this, New](BasicBlock *Succ) {
+    Succ->replacePhiUsesWith(this, New);
+  });
   return New;
 }
 
+void BasicBlock::replacePhiUsesWith(BasicBlock *Old, BasicBlock *New) {
+  // N.B. This might not be a complete BasicBlock, so don't assume
+  // that it ends with a non-phi instruction.
+  for (iterator II = begin(), IE = end(); II != IE; ++II) {
+    PHINode *PN = dyn_cast<PHINode>(II);
+    if (!PN)
+      break;
+    PN->replaceIncomingBlockWith(Old, New);
+  }
+}
+
 void BasicBlock::replaceSuccessorsPhiUsesWith(BasicBlock *New) {
   Instruction *TI = getTerminator();
   if (!TI)
     // Cope with being called on a BasicBlock that doesn't have a terminator
     // yet. Clang's CodeGenFunction::EmitReturnBlock() likes to do this.
     return;
-  for (BasicBlock *Succ : successors(TI)) {
-    // N.B. Succ might not be a complete BasicBlock, so don't assume
-    // that it ends with a non-phi instruction.
-    for (iterator II = Succ->begin(), IE = Succ->end(); II != IE; ++II) {
-      PHINode *PN = dyn_cast<PHINode>(II);
-      if (!PN)
-        break;
-      PN->replaceIncomingBlockWith(this, New);
-    }
-  }
+  llvm::for_each(successors(TI), [this, New](BasicBlock *Succ) {
+    Succ->replacePhiUsesWith(this, New);
+  });
 }
 
 /// Return true if this basic block is a landing pad. I.e., it's

lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp

@@ -1325,8 +1325,7 @@ LoopConstrainer::RewrittenRangeInfo LoopConstrainer::changeIterationSpaceEnd(
 
   // The latch exit now has a branch from `RRI.ExitSelector' instead of
   // `LS.Latch'.  The PHI nodes need to be updated to reflect that.
-  for (PHINode &PN : LS.LatchExit->phis())
-    PN.replaceIncomingBlockWith(LS.Latch, RRI.ExitSelector);
+  LS.LatchExit->replacePhiUsesWith(LS.Latch, RRI.ExitSelector);
 
   return RRI;
 }
@@ -1349,8 +1348,7 @@ BasicBlock *LoopConstrainer::createPreheader(const LoopStructure &LS,
   BasicBlock *Preheader = BasicBlock::Create(Ctx, Tag, &F, LS.Header);
   BranchInst::Create(LS.Header, Preheader);
 
-  for (PHINode &PN : LS.Header->phis())
-    PN.replaceIncomingBlockWith(OldPreheader, Preheader);
+  LS.Header->replacePhiUsesWith(OldPreheader, Preheader);
 
   return Preheader;
 }

lib/Transforms/Scalar/LoopInterchange.cpp

@@ -1279,12 +1279,6 @@ static void moveBBContents(BasicBlock *FromBB, Instruction *InsertBefore) {
                 FromBB->getTerminator()->getIterator());
 }
 
-static void updateIncomingBlock(BasicBlock *CurrBlock, BasicBlock *OldPred,
-                                BasicBlock *NewPred) {
-  for (PHINode &PHI : CurrBlock->phis())
-    PHI.replaceIncomingBlockWith(OldPred, NewPred);
-}
-
 /// Update BI to jump to NewBB instead of OldBB. Records updates to
 /// the dominator tree in DTUpdates, if DT should be preserved.
 static void updateSuccessor(BranchInst *BI, BasicBlock *OldBB,
@@ -1349,7 +1343,7 @@ static void moveLCSSAPhis(BasicBlock *InnerExit, BasicBlock *InnerLatch,
   // Now adjust the incoming blocks for the LCSSA PHIs.
   // For PHIs moved from Inner's exit block, we need to replace Inner's latch
   // with the new latch.
-  updateIncomingBlock(InnerLatch, InnerLatch, OuterLatch);
+  InnerLatch->replacePhiUsesWith(InnerLatch, OuterLatch);
 }
 
 bool LoopInterchangeTransform::adjustLoopBranches() {
@@ -1416,8 +1410,8 @@ bool LoopInterchangeTransform::adjustLoopBranches() {
                   InnerLoopHeaderSuccessor, DTUpdates);
 
   // Adjust reduction PHI's now that the incoming block has changed.
-  updateIncomingBlock(InnerLoopHeaderSuccessor, InnerLoopHeader,
-                      OuterLoopHeader);
+  InnerLoopHeaderSuccessor->replacePhiUsesWith(InnerLoopHeader,
+                                               OuterLoopHeader);
 
   updateSuccessor(InnerLoopHeaderBI, InnerLoopHeaderSuccessor,
                   OuterLoopPreHeader, DTUpdates);
@@ -1449,7 +1443,7 @@ bool LoopInterchangeTransform::adjustLoopBranches() {
   moveLCSSAPhis(InnerLoopLatchSuccessor, InnerLoopLatch, OuterLoopLatch);
   // For PHIs in the exit block of the outer loop, outer's latch has been
   // replaced by Inners'.
-  updateIncomingBlock(OuterLoopLatchSuccessor, OuterLoopLatch, InnerLoopLatch);
+  OuterLoopLatchSuccessor->replacePhiUsesWith(OuterLoopLatch, InnerLoopLatch);
 
   // Now update the reduction PHIs in the inner and outer loop headers.
   SmallVector<PHINode *, 4> InnerLoopPHIs, OuterLoopPHIs;
@@ -1476,10 +1470,10 @@ bool LoopInterchangeTransform::adjustLoopBranches() {
   }
 
   // Update the incoming blocks for moved PHI nodes.
-  updateIncomingBlock(OuterLoopHeader, InnerLoopPreHeader, OuterLoopPreHeader);
-  updateIncomingBlock(OuterLoopHeader, InnerLoopLatch, OuterLoopLatch);
-  updateIncomingBlock(InnerLoopHeader, OuterLoopPreHeader, InnerLoopPreHeader);
-  updateIncomingBlock(InnerLoopHeader, OuterLoopLatch, InnerLoopLatch);
+  OuterLoopHeader->replacePhiUsesWith(InnerLoopPreHeader, OuterLoopPreHeader);
+  OuterLoopHeader->replacePhiUsesWith(InnerLoopLatch, OuterLoopLatch);
+  InnerLoopHeader->replacePhiUsesWith(OuterLoopPreHeader, InnerLoopPreHeader);
+  InnerLoopHeader->replacePhiUsesWith(OuterLoopLatch, InnerLoopLatch);
 
   return true;
 }