InstSimplify: Move a transform from InstCombine to InstSimplify

[oota-llvm.git] / lib / Transforms / Utils / FlattenCFG.cpp

diff --git a/lib/Transforms/Utils/FlattenCFG.cpp b/lib/Transforms/Utils/FlattenCFG.cpp
index 656e8976aa55e83ba595e064877f7265ddefd4df..4eb3e3dd17d28540e1f2abc51a4b69d5b7cf3be5 100644 (file)
--- a/lib/Transforms/Utils/FlattenCFG.cpp
+++ b/lib/Transforms/Utils/FlattenCFG.cpp
@@ -11,26 +11,29 @@
 //
 //===----------------------------------------------------------------------===//
 
-#define DEBUG_TYPE "flattencfg"
 #include "llvm/Transforms/Utils/Local.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/Analysis/AliasAnalysis.h"
 #include "llvm/Analysis/ValueTracking.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 using namespace llvm;
 
+#define DEBUG_TYPE "flattencfg"
+
 namespace {
 class FlattenCFGOpt {
   AliasAnalysis *AA;
   /// \brief Use parallel-and or parallel-or to generate conditions for
   /// conditional branches.
-  bool FlattenParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder, Pass *P = 0);
+  bool FlattenParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder,
+                            Pass *P = nullptr);
   /// \brief If \param BB is the merge block of an if-region, attempt to merge
   /// the if-region with an adjacent if-region upstream if two if-regions
   /// contain identical instructions.
-  bool MergeIfRegion(BasicBlock *BB, IRBuilder<> &Builder, Pass *P = 0);
+  bool MergeIfRegion(BasicBlock *BB, IRBuilder<> &Builder, Pass *P = nullptr);
   /// \brief Compare a pair of blocks: \p Block1 and \p Block2, which
   /// are from two if-regions whose entry blocks are \p Head1 and \p
   /// Head2.  \returns true if \p Block1 and \p Block2 contain identical
@@ -125,9 +128,9 @@ bool FlattenCFGOpt::FlattenParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder,
   if (PHI)
     return false; // For simplicity, avoid cases containing PHI nodes.
 
-  BasicBlock *LastCondBlock = NULL;
-  BasicBlock *FirstCondBlock = NULL;
-  BasicBlock *UnCondBlock = NULL;
+  BasicBlock *LastCondBlock = nullptr;
+  BasicBlock *FirstCondBlock = nullptr;
+  BasicBlock *UnCondBlock = nullptr;
   int Idx = -1;
 
   // Check predecessors of \param BB.
@@ -235,19 +238,20 @@ bool FlattenCFGOpt::FlattenParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder,
     // Do branch inversion.
     BasicBlock *CurrBlock = LastCondBlock;
     bool EverChanged = false;
-    while (1) {
+    for (;CurrBlock != FirstCondBlock;
+          CurrBlock = CurrBlock->getSinglePredecessor()) {
       BranchInst *BI = dyn_cast<BranchInst>(CurrBlock->getTerminator());
       CmpInst *CI = dyn_cast<CmpInst>(BI->getCondition());
+      if (!CI)
+        continue;
+
       CmpInst::Predicate Predicate = CI->getPredicate();
-      // Cannonicalize icmp_ne -> icmp_eq, fcmp_one -> fcmp_oeq
+      // Canonicalize icmp_ne -> icmp_eq, fcmp_one -> fcmp_oeq
       if ((Predicate == CmpInst::ICMP_NE) || (Predicate == CmpInst::FCMP_ONE)) {
         CI->setPredicate(ICmpInst::getInversePredicate(Predicate));
         BI->swapSuccessors();
         EverChanged = true;
       }
-      if (CurrBlock == FirstCondBlock)
-        break;
-      CurrBlock = CurrBlock->getSinglePredecessor();
     }
     return EverChanged;
   }
@@ -265,8 +269,7 @@ bool FlattenCFGOpt::FlattenParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder,
   BasicBlock *CB;
   BranchInst *PBI = dyn_cast<BranchInst>(FirstCondBlock->getTerminator());
   bool Iteration = true;
-  BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
-  BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
+  IRBuilder<>::InsertPointGuard Guard(Builder);
   Value *PC = PBI->getCondition();
 
   do {
@@ -297,7 +300,6 @@ bool FlattenCFGOpt::FlattenParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder,
     new UnreachableInst(CB->getContext(), CB);
   } while (Iteration);
 
-  Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt);
   DEBUG(dbgs() << "Use parallel and/or in:\n" << *FirstCondBlock);
   return true;
 }
@@ -371,7 +373,7 @@ bool FlattenCFGOpt::CompareIfRegionBlock(BasicBlock *Head1, BasicBlock *Head2,
 
 /// Check whether \param BB is the merge block of a if-region.  If yes, check
 /// whether there exists an adjacent if-region upstream, the two if-regions
-/// contain identical instuctions and can be legally merged.  \returns true if
+/// contain identical instructions and can be legally merged.  \returns true if
 /// the two if-regions are merged.
 ///
 /// From: