[llvm] r187764 - Factor FlattenCFG out from SimplifyCFG

Timur Iskhodzhanov timurrrr at google.com
Tue Aug 6 01:43:25 PDT 2013


FYI this has broken the MSVS build

100>------ Build started: Project: LLVMTransformUtils, Configuration:
Debug Win32 ------
...
100> FlattenCFG.cpp
100> llvm\lib\Transforms\Utils\FlattenCFG.cpp(301):
  error C2027: use of undefined type 'llvm::raw_ostream'

2013/8/6 Tom Stellard <thomas.stellard at amd.com>:
> Author: tstellar
> Date: Mon Aug  5 21:43:45 2013
> New Revision: 187764
>
> URL: http://llvm.org/viewvc/llvm-project?rev=187764&view=rev
> Log:
> Factor FlattenCFG out from SimplifyCFG
>
> Patch by: Mei Ye
>
> Added:
>     llvm/trunk/lib/Transforms/Scalar/FlattenCFGPass.cpp
>     llvm/trunk/lib/Transforms/Utils/FlattenCFG.cpp
>     llvm/trunk/test/CodeGen/R600/parallelandifcollapse.ll
>       - copied, changed from r187754, llvm/trunk/test/Transforms/SimplifyCFG/R600/parallelorifcollapse.ll
>     llvm/trunk/test/CodeGen/R600/parallelorifcollapse.ll
>       - copied, changed from r187754, llvm/trunk/test/Transforms/SimplifyCFG/R600/parallelandifcollapse.ll
> Modified:
>     llvm/trunk/include/llvm/InitializePasses.h
>     llvm/trunk/include/llvm/Transforms/Scalar.h
>     llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h
>     llvm/trunk/include/llvm/Transforms/Utils/Local.h
>     llvm/trunk/lib/Target/R600/AMDGPUTargetMachine.cpp
>     llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
>     llvm/trunk/lib/Transforms/Scalar/CMakeLists.txt
>     llvm/trunk/lib/Transforms/Scalar/Scalar.cpp
>     llvm/trunk/lib/Transforms/Scalar/SimplifyCFGPass.cpp
>     llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp
>     llvm/trunk/lib/Transforms/Utils/CMakeLists.txt
>     llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
>     llvm/trunk/test/Transforms/SimplifyCFG/R600/lit.local.cfg
>     llvm/trunk/test/Transforms/SimplifyCFG/R600/parallelandifcollapse.ll
>     llvm/trunk/test/Transforms/SimplifyCFG/R600/parallelorifcollapse.ll
>     llvm/trunk/test/Transforms/SimplifyCFG/lit.local.cfg
>     llvm/trunk/tools/lto/LTOCodeGenerator.cpp
>
> Modified: llvm/trunk/include/llvm/InitializePasses.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/InitializePasses.h?rev=187764&r1=187763&r2=187764&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/InitializePasses.h (original)
> +++ llvm/trunk/include/llvm/InitializePasses.h Mon Aug  5 21:43:45 2013
> @@ -86,8 +86,8 @@ void initializeCallGraphViewerPass(PassR
>  void initializeCFGOnlyPrinterPass(PassRegistry&);
>  void initializeCFGOnlyViewerPass(PassRegistry&);
>  void initializeCFGPrinterPass(PassRegistry&);
> -void initializeCFGOptimizePass(PassRegistry&);
> -void initializeCFGCanonicalizePass(PassRegistry&);
> +void initializeCFGSimplifyPassPass(PassRegistry&);
> +void initializeFlattenCFGPassPass(PassRegistry&);
>  void initializeStructurizeCFGPass(PassRegistry&);
>  void initializeCFGViewerPass(PassRegistry&);
>  void initializeCalculateSpillWeightsPass(PassRegistry&);
>
> Modified: llvm/trunk/include/llvm/Transforms/Scalar.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Scalar.h?rev=187764&r1=187763&r2=187764&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/Transforms/Scalar.h (original)
> +++ llvm/trunk/include/llvm/Transforms/Scalar.h Mon Aug  5 21:43:45 2013
> @@ -196,7 +196,14 @@ FunctionPass *createJumpThreadingPass();
>  // CFGSimplification - Merge basic blocks, eliminate unreachable blocks,
>  // simplify terminator instructions, etc...
>  //
> -FunctionPass *createCFGSimplificationPass(bool IsTargetAware = false);
> +FunctionPass *createCFGSimplificationPass();
> +
> +//===----------------------------------------------------------------------===//
> +//
> +// FlattenCFG - flatten CFG, reduce number of conditional branches by using
> +// parallel-and and parallel-or mode, etc...
> +//
> +FunctionPass *createFlattenCFGPass();
>
>  //===----------------------------------------------------------------------===//
>  //
>
> Modified: llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h?rev=187764&r1=187763&r2=187764&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h (original)
> +++ llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h Mon Aug  5 21:43:45 2013
> @@ -205,6 +205,15 @@ ReturnInst *FoldReturnIntoUncondBranch(R
>  TerminatorInst *SplitBlockAndInsertIfThen(Instruction *Cmp,
>      bool Unreachable, MDNode *BranchWeights = 0);
>
> +///
> +/// GetIfCondition - Check whether BB is the merge point of a if-region.
> +/// If so, return the boolean condition that determines which entry into
> +/// BB will be taken.  Also, return by references the block that will be
> +/// entered from if the condition is true, and the block that will be
> +/// entered if the condition is false.
> +
> +Value *GetIfCondition(BasicBlock *BB, BasicBlock *&IfTrue,
> +                     BasicBlock *&IfFalse);
>  } // End llvm namespace
>
>  #endif
>
> Modified: llvm/trunk/include/llvm/Transforms/Utils/Local.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/Local.h?rev=187764&r1=187763&r2=187764&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/Transforms/Utils/Local.h (original)
> +++ llvm/trunk/include/llvm/Transforms/Utils/Local.h Mon Aug  5 21:43:45 2013
> @@ -137,7 +137,13 @@ bool EliminateDuplicatePHINodes(BasicBlo
>  /// the basic block that was pointed to.
>  ///
>  bool SimplifyCFG(BasicBlock *BB, const TargetTransformInfo &TTI,
> -                 const DataLayout *TD = 0, AliasAnalysis *AA = 0);
> +                 const DataLayout *TD = 0);
> +
> +/// FlatternCFG - This function is used to flatten a CFG.  For
> +/// example, it uses parallel-and and parallel-or mode to collapse
> +//  if-conditions and merge if-regions with identical statements.
> +///
> +bool FlattenCFG(BasicBlock *BB, AliasAnalysis *AA = 0);
>
>  /// FoldBranchToCommonDest - If this basic block is ONLY a setcc and a branch,
>  /// and if a predecessor branches to us and one of our successors, fold the
>
> Modified: llvm/trunk/lib/Target/R600/AMDGPUTargetMachine.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/R600/AMDGPUTargetMachine.cpp?rev=187764&r1=187763&r2=187764&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Target/R600/AMDGPUTargetMachine.cpp (original)
> +++ llvm/trunk/lib/Target/R600/AMDGPUTargetMachine.cpp Mon Aug  5 21:43:45 2013
> @@ -91,7 +91,6 @@ public:
>    AMDGPUTargetMachine &getAMDGPUTargetMachine() const {
>      return getTM<AMDGPUTargetMachine>();
>    }
> -
>    virtual bool addPreISel();
>    virtual bool addInstSelector();
>    virtual bool addPreRegAlloc();
> @@ -120,6 +119,7 @@ void AMDGPUTargetMachine::addAnalysisPas
>  bool
>  AMDGPUPassConfig::addPreISel() {
>    const AMDGPUSubtarget &ST = TM->getSubtarget<AMDGPUSubtarget>();
> +  addPass(createFlattenCFGPass());
>    if (ST.getGeneration() > AMDGPUSubtarget::NORTHERN_ISLANDS) {
>      addPass(createStructurizeCFGPass());
>      addPass(createSIAnnotateControlFlowPass());
>
> Modified: llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp?rev=187764&r1=187763&r2=187764&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp (original)
> +++ llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp Mon Aug  5 21:43:45 2013
> @@ -235,7 +235,7 @@ void PassManagerBuilder::populateModuleP
>    }
>
>    MPM.add(createAggressiveDCEPass());         // Delete dead instructions
> -  MPM.add(createCFGSimplificationPass(true)); // Merge & remove BBs
> +  MPM.add(createCFGSimplificationPass()); // Merge & remove BBs
>    MPM.add(createInstructionCombiningPass());  // Clean up after everything.
>
>    // As an experimental mode, run any vectorization passes in a separate
> @@ -371,7 +371,7 @@ void PassManagerBuilder::populateLTOPass
>    PM.add(createJumpThreadingPass());
>
>    // Delete basic blocks, which optimization passes may have killed.
> -  PM.add(createCFGSimplificationPass(true));
> +  PM.add(createCFGSimplificationPass());
>
>    // Now that we have optimized the program, discard unreachable functions.
>    PM.add(createGlobalDCEPass());
>
> Modified: llvm/trunk/lib/Transforms/Scalar/CMakeLists.txt
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/CMakeLists.txt?rev=187764&r1=187763&r2=187764&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Scalar/CMakeLists.txt (original)
> +++ llvm/trunk/lib/Transforms/Scalar/CMakeLists.txt Mon Aug  5 21:43:45 2013
> @@ -28,6 +28,7 @@ add_llvm_library(LLVMScalarOpts
>    Scalar.cpp
>    ScalarReplAggregates.cpp
>    SimplifyCFGPass.cpp
> +  FlattenCFGPass.cpp
>    Sink.cpp
>    StructurizeCFG.cpp
>    TailRecursionElimination.cpp
>
> Added: llvm/trunk/lib/Transforms/Scalar/FlattenCFGPass.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/FlattenCFGPass.cpp?rev=187764&view=auto
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Scalar/FlattenCFGPass.cpp (added)
> +++ llvm/trunk/lib/Transforms/Scalar/FlattenCFGPass.cpp Mon Aug  5 21:43:45 2013
> @@ -0,0 +1,79 @@
> +//===- FlattenCFGPass.cpp - CFG Flatten Pass ----------------------===//
> +//
> +//                     The LLVM Compiler Infrastructure
> +//
> +// This file is distributed under the University of Illinois Open Source
> +// License. See LICENSE.TXT for details.
> +//
> +//===----------------------------------------------------------------------===//
> +//
> +// This file implements flattening of CFG.
> +//
> +//===----------------------------------------------------------------------===//
> +
> +#define DEBUG_TYPE "flattencfg"
> +#include "llvm/Transforms/Scalar.h"
> +#include "llvm/Analysis/AliasAnalysis.h"
> +#include "llvm/Pass.h"
> +#include "llvm/Support/CFG.h"
> +#include "llvm/Transforms/Utils/Local.h"
> +using namespace llvm;
> +
> +namespace {
> +struct FlattenCFGPass : public FunctionPass {
> +  static char ID; // Pass identification, replacement for typeid
> +public:
> +  FlattenCFGPass() : FunctionPass(ID) {
> +    initializeFlattenCFGPassPass(*PassRegistry::getPassRegistry());
> +  }
> +  bool runOnFunction(Function &F);
> +
> +  void getAnalysisUsage(AnalysisUsage &AU) const {
> +    AU.addRequired<AliasAnalysis>();
> +  }
> +
> +private:
> +  AliasAnalysis *AA;
> +};
> +}
> +
> +char FlattenCFGPass::ID = 0;
> +INITIALIZE_PASS_BEGIN(FlattenCFGPass, "flattencfg", "Flatten the CFG", false,
> +                      false)
> +INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
> +INITIALIZE_PASS_END(FlattenCFGPass, "flattencfg", "Flatten the CFG", false,
> +                    false)
> +
> +// Public interface to the FlattenCFG pass
> +FunctionPass *llvm::createFlattenCFGPass() { return new FlattenCFGPass(); }
> +
> +/// iterativelyFlattenCFG - Call FlattenCFG on all the blocks in the function,
> +/// iterating until no more changes are made.
> +static bool iterativelyFlattenCFG(Function &F, AliasAnalysis *AA) {
> +  bool Changed = false;
> +  bool LocalChange = true;
> +  while (LocalChange) {
> +    LocalChange = false;
> +
> +    // Loop over all of the basic blocks and remove them if they are unneeded...
> +    //
> +    for (Function::iterator BBIt = F.begin(); BBIt != F.end();) {
> +      if (FlattenCFG(BBIt++, AA)) {
> +        LocalChange = true;
> +      }
> +    }
> +    Changed |= LocalChange;
> +  }
> +  return Changed;
> +}
> +
> +bool FlattenCFGPass::runOnFunction(Function &F) {
> +  AA = &getAnalysis<AliasAnalysis>();
> +  bool EverChanged = false;
> +  // iterativelyFlattenCFG can make some blocks dead.
> +  while (iterativelyFlattenCFG(F, AA)) {
> +    removeUnreachableBlocks(F);
> +    EverChanged = true;
> +  }
> +  return EverChanged;
> +}
>
> Modified: llvm/trunk/lib/Transforms/Scalar/Scalar.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/Scalar.cpp?rev=187764&r1=187763&r2=187764&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Scalar/Scalar.cpp (original)
> +++ llvm/trunk/lib/Transforms/Scalar/Scalar.cpp Mon Aug  5 21:43:45 2013
> @@ -57,8 +57,7 @@ void llvm::initializeScalarOpts(PassRegi
>    initializeSROAPass(Registry);
>    initializeSROA_DTPass(Registry);
>    initializeSROA_SSAUpPass(Registry);
> -  initializeCFGCanonicalizePass(Registry);
> -  initializeCFGOptimizePass(Registry);
> +  initializeCFGSimplifyPassPass(Registry);
>    initializeStructurizeCFGPass(Registry);
>    initializeSinkingPass(Registry);
>    initializeTailCallElimPass(Registry);
>
> Modified: llvm/trunk/lib/Transforms/Scalar/SimplifyCFGPass.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SimplifyCFGPass.cpp?rev=187764&r1=187763&r2=187764&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Scalar/SimplifyCFGPass.cpp (original)
> +++ llvm/trunk/lib/Transforms/Scalar/SimplifyCFGPass.cpp Mon Aug  5 21:43:45 2013
> @@ -27,7 +27,6 @@
>  #include "llvm/ADT/SmallVector.h"
>  #include "llvm/ADT/Statistic.h"
>  #include "llvm/Analysis/TargetTransformInfo.h"
> -#include "llvm/Analysis/AliasAnalysis.h"
>  #include "llvm/IR/Attributes.h"
>  #include "llvm/IR/Constants.h"
>  #include "llvm/IR/DataLayout.h"
> @@ -43,61 +42,28 @@ STATISTIC(NumSimpl, "Number of blocks si
>
>  namespace {
>  struct CFGSimplifyPass : public FunctionPass {
> -  CFGSimplifyPass(char &ID, bool isTargetAware)
> -      : FunctionPass(ID), IsTargetAware(isTargetAware) {}
> -  virtual bool runOnFunction(Function &F);
> -
> -  virtual void getAnalysisUsage(AnalysisUsage &AU) const {
> -    AU.addRequired<TargetTransformInfo>();
> -  }
> -private:
> -  AliasAnalysis *AA;
> -  bool IsTargetAware; // Should the pass be target-aware?
> -};
> -
> -// CFGSimplifyPass that does optimizations.
> -struct CFGOptimize : public CFGSimplifyPass {
>    static char ID; // Pass identification, replacement for typeid
> -public:
> -  CFGOptimize() : CFGSimplifyPass(ID, true) {
> -    initializeCFGOptimizePass(*PassRegistry::getPassRegistry());
> +  CFGSimplifyPass() : FunctionPass(ID) {
> +    initializeCFGSimplifyPassPass(*PassRegistry::getPassRegistry());
>    }
> +  virtual bool runOnFunction(Function &F);
> +
>    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
>      AU.addRequired<TargetTransformInfo>();
> -    AU.addRequired<AliasAnalysis>();
> -  }
> -};
> -
> -// CFGSimplifyPass that does canonicalizations.
> -struct CFGCanonicalize : public CFGSimplifyPass {
> -  static char ID; // Pass identification, replacement for typeid
> -public:
> -  CFGCanonicalize() : CFGSimplifyPass(ID, false) {
> -    initializeCFGCanonicalizePass(*PassRegistry::getPassRegistry());
>    }
>  };
>  }
>
> -char CFGCanonicalize::ID = 0;
> -char CFGOptimize::ID = 0;
> -INITIALIZE_PASS_BEGIN(CFGCanonicalize, "simplifycfg", "Simplify the CFG", false,
> -                      false)
> -INITIALIZE_AG_DEPENDENCY(TargetTransformInfo)
> -INITIALIZE_PASS_END(CFGCanonicalize, "simplifycfg", "Simplify the CFG", false,
> -                    false)
> -INITIALIZE_PASS_BEGIN(CFGOptimize, "optimizecfg", "optimize the CFG", false,
> +char CFGSimplifyPass::ID = 0;
> +INITIALIZE_PASS_BEGIN(CFGSimplifyPass, "simplifycfg", "Simplify the CFG", false,
>                        false)
>  INITIALIZE_AG_DEPENDENCY(TargetTransformInfo)
> -INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
> -INITIALIZE_PASS_END(CFGOptimize, "optimizecfg", "Optimize the CFG", false,
> +INITIALIZE_PASS_END(CFGSimplifyPass, "simplifycfg", "Simplify the CFG", false,
>                      false)
>
>  // Public interface to the CFGSimplification pass
> -FunctionPass *llvm::createCFGSimplificationPass(bool IsTargetAware) {
> -  if (IsTargetAware)
> -    return new CFGOptimize();
> -  else
> -    return new CFGCanonicalize();
> +FunctionPass *llvm::createCFGSimplificationPass() {
> +  return new CFGSimplifyPass();
>  }
>
>  /// changeToUnreachable - Insert an unreachable instruction before the specified
> @@ -334,7 +300,7 @@ static bool mergeEmptyReturnBlocks(Funct
>  /// iterativelySimplifyCFG - Call SimplifyCFG on all the blocks in the function,
>  /// iterating until no more changes are made.
>  static bool iterativelySimplifyCFG(Function &F, const TargetTransformInfo &TTI,
> -                                   const DataLayout *TD, AliasAnalysis *AA) {
> +                                   const DataLayout *TD) {
>    bool Changed = false;
>    bool LocalChange = true;
>    while (LocalChange) {
> @@ -343,7 +309,7 @@ static bool iterativelySimplifyCFG(Funct
>      // Loop over all of the basic blocks and remove them if they are unneeded...
>      //
>      for (Function::iterator BBIt = F.begin(); BBIt != F.end(); ) {
> -      if (SimplifyCFG(BBIt++, TTI, TD, AA)) {
> +      if (SimplifyCFG(BBIt++, TTI, TD)) {
>          LocalChange = true;
>          ++NumSimpl;
>        }
> @@ -357,15 +323,11 @@ static bool iterativelySimplifyCFG(Funct
>  // simplify the CFG.
>  //
>  bool CFGSimplifyPass::runOnFunction(Function &F) {
> -  if (IsTargetAware)
> -    AA = &getAnalysis<AliasAnalysis>();
> -  else
> -    AA = NULL;
>    const TargetTransformInfo &TTI = getAnalysis<TargetTransformInfo>();
>    const DataLayout *TD = getAnalysisIfAvailable<DataLayout>();
>    bool EverChanged = removeUnreachableBlocksFromFn(F);
>    EverChanged |= mergeEmptyReturnBlocks(F);
> -  EverChanged |= iterativelySimplifyCFG(F, TTI, TD, AA);
> +  EverChanged |= iterativelySimplifyCFG(F, TTI, TD);
>
>    // If neither pass changed anything, we're done.
>    if (!EverChanged) return false;
> @@ -379,7 +341,7 @@ bool CFGSimplifyPass::runOnFunction(Func
>      return true;
>
>    do {
> -    EverChanged = iterativelySimplifyCFG(F, TTI, TD, AA);
> +    EverChanged = iterativelySimplifyCFG(F, TTI, TD);
>      EverChanged |= removeUnreachableBlocksFromFn(F);
>    } while (EverChanged);
>
>
> Modified: llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp?rev=187764&r1=187763&r2=187764&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp (original)
> +++ llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp Mon Aug  5 21:43:45 2013
> @@ -665,3 +665,104 @@ TerminatorInst *llvm::SplitBlockAndInser
>    ReplaceInstWithInst(HeadOldTerm, HeadNewTerm);
>    return CheckTerm;
>  }
> +
> +/// GetIfCondition - Given a basic block (BB) with two predecessors,
> +/// check to see if the merge at this block is due
> +/// to an "if condition".  If so, return the boolean condition that determines
> +/// which entry into BB will be taken.  Also, return by references the block
> +/// that will be entered from if the condition is true, and the block that will
> +/// be entered if the condition is false.
> +///
> +/// This does no checking to see if the true/false blocks have large or unsavory
> +/// instructions in them.
> +Value *llvm::GetIfCondition(BasicBlock *BB, BasicBlock *&IfTrue,
> +                             BasicBlock *&IfFalse) {
> +  PHINode *SomePHI = dyn_cast<PHINode>(BB->begin());
> +  BasicBlock *Pred1 = NULL;
> +  BasicBlock *Pred2 = NULL;
> +
> +  if (SomePHI) {
> +    if (SomePHI->getNumIncomingValues() != 2)
> +      return NULL;
> +    Pred1 = SomePHI->getIncomingBlock(0);
> +    Pred2 = SomePHI->getIncomingBlock(1);
> +  } else {
> +    pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
> +    if (PI == PE) // No predecessor
> +      return NULL;
> +    Pred1 = *PI++;
> +    if (PI == PE) // Only one predecessor
> +      return NULL;
> +    Pred2 = *PI++;
> +    if (PI != PE) // More than two predecessors
> +      return NULL;
> +  }
> +
> +  // We can only handle branches.  Other control flow will be lowered to
> +  // branches if possible anyway.
> +  BranchInst *Pred1Br = dyn_cast<BranchInst>(Pred1->getTerminator());
> +  BranchInst *Pred2Br = dyn_cast<BranchInst>(Pred2->getTerminator());
> +  if (Pred1Br == 0 || Pred2Br == 0)
> +    return 0;
> +
> +  // Eliminate code duplication by ensuring that Pred1Br is conditional if
> +  // either are.
> +  if (Pred2Br->isConditional()) {
> +    // If both branches are conditional, we don't have an "if statement".  In
> +    // reality, we could transform this case, but since the condition will be
> +    // required anyway, we stand no chance of eliminating it, so the xform is
> +    // probably not profitable.
> +    if (Pred1Br->isConditional())
> +      return 0;
> +
> +    std::swap(Pred1, Pred2);
> +    std::swap(Pred1Br, Pred2Br);
> +  }
> +
> +  if (Pred1Br->isConditional()) {
> +    // The only thing we have to watch out for here is to make sure that Pred2
> +    // doesn't have incoming edges from other blocks.  If it does, the condition
> +    // doesn't dominate BB.
> +    if (Pred2->getSinglePredecessor() == 0)
> +      return 0;
> +
> +    // If we found a conditional branch predecessor, make sure that it branches
> +    // to BB and Pred2Br.  If it doesn't, this isn't an "if statement".
> +    if (Pred1Br->getSuccessor(0) == BB &&
> +        Pred1Br->getSuccessor(1) == Pred2) {
> +      IfTrue = Pred1;
> +      IfFalse = Pred2;
> +    } else if (Pred1Br->getSuccessor(0) == Pred2 &&
> +               Pred1Br->getSuccessor(1) == BB) {
> +      IfTrue = Pred2;
> +      IfFalse = Pred1;
> +    } else {
> +      // We know that one arm of the conditional goes to BB, so the other must
> +      // go somewhere unrelated, and this must not be an "if statement".
> +      return 0;
> +    }
> +
> +    return Pred1Br->getCondition();
> +  }
> +
> +  // Ok, if we got here, both predecessors end with an unconditional branch to
> +  // BB.  Don't panic!  If both blocks only have a single (identical)
> +  // predecessor, and THAT is a conditional branch, then we're all ok!
> +  BasicBlock *CommonPred = Pred1->getSinglePredecessor();
> +  if (CommonPred == 0 || CommonPred != Pred2->getSinglePredecessor())
> +    return 0;
> +
> +  // Otherwise, if this is a conditional branch, then we can use it!
> +  BranchInst *BI = dyn_cast<BranchInst>(CommonPred->getTerminator());
> +  if (BI == 0) return 0;
> +
> +  assert(BI->isConditional() && "Two successors but not conditional?");
> +  if (BI->getSuccessor(0) == Pred1) {
> +    IfTrue = Pred1;
> +    IfFalse = Pred2;
> +  } else {
> +    IfTrue = Pred2;
> +    IfFalse = Pred1;
> +  }
> +  return BI->getCondition();
> +}
>
> Modified: llvm/trunk/lib/Transforms/Utils/CMakeLists.txt
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/CMakeLists.txt?rev=187764&r1=187763&r2=187764&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Utils/CMakeLists.txt (original)
> +++ llvm/trunk/lib/Transforms/Utils/CMakeLists.txt Mon Aug  5 21:43:45 2013
> @@ -25,6 +25,7 @@ add_llvm_library(LLVMTransformUtils
>    PromoteMemoryToRegister.cpp
>    SSAUpdater.cpp
>    SimplifyCFG.cpp
> +  FlattenCFG.cpp
>    SimplifyIndVar.cpp
>    SimplifyInstructions.cpp
>    SimplifyLibCalls.cpp
>
> Added: llvm/trunk/lib/Transforms/Utils/FlattenCFG.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/FlattenCFG.cpp?rev=187764&view=auto
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Utils/FlattenCFG.cpp (added)
> +++ llvm/trunk/lib/Transforms/Utils/FlattenCFG.cpp Mon Aug  5 21:43:45 2013
> @@ -0,0 +1,487 @@
> +//===- FlatternCFG.cpp - Code to perform CFG flattening ---------------===//
> +//
> +//                     The LLVM Compiler Infrastructure
> +//
> +// This file is distributed under the University of Illinois Open Source
> +// License. See LICENSE.TXT for details.
> +//
> +//===----------------------------------------------------------------------===//
> +//
> +// Reduce conditional branches in CFG.
> +//
> +//===----------------------------------------------------------------------===//
> +
> +#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/Transforms/Utils/BasicBlockUtils.h"
> +using namespace llvm;
> +
> +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);
> +  /// \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);
> +  /// \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
> +  /// instructions, and have no memory reference alias with \p Head2.
> +  /// This is used as a legality check for merging if-regions.
> +  bool CompareIfRegionBlock(BasicBlock *Head1, BasicBlock *Head2,
> +                            BasicBlock *Block1, BasicBlock *Block2);
> +
> +public:
> +  FlattenCFGOpt(AliasAnalysis *AA) : AA(AA) {}
> +  bool run(BasicBlock *BB);
> +};
> +}
> +
> +/// If \param [in] BB has more than one predecessor that is a conditional
> +/// branch, attempt to use parallel and/or for the branch condition. \returns
> +/// true on success.
> +///
> +/// Before:
> +///   ......
> +///   %cmp10 = fcmp une float %tmp1, %tmp2
> +///   br i1 %cmp1, label %if.then, label %lor.rhs
> +///
> +/// lor.rhs:
> +///   ......
> +///   %cmp11 = fcmp une float %tmp3, %tmp4
> +///   br i1 %cmp11, label %if.then, label %ifend
> +///
> +/// if.end:  // the merge block
> +///   ......
> +///
> +/// if.then: // has two predecessors, both of them contains conditional branch.
> +///   ......
> +///   br label %if.end;
> +///
> +/// After:
> +///  ......
> +///  %cmp10 = fcmp une float %tmp1, %tmp2
> +///  ......
> +///  %cmp11 = fcmp une float %tmp3, %tmp4
> +///  %cmp12 = or i1 %cmp10, %cmp11    // parallel-or mode.
> +///  br i1 %cmp12, label %if.then, label %ifend
> +///
> +///  if.end:
> +///    ......
> +///
> +///  if.then:
> +///    ......
> +///    br label %if.end;
> +///
> +///  Current implementation handles two cases.
> +///  Case 1: \param BB is on the else-path.
> +///
> +///          BB1
> +///        /     |
> +///       BB2    |
> +///      /   \   |
> +///     BB3   \  |     where, BB1, BB2 contain conditional branches.
> +///      \    |  /     BB3 contains unconditional branch.
> +///       \   | /      BB4 corresponds to \param BB which is also the merge.
> +///  BB => BB4
> +///
> +///
> +///  Corresponding source code:
> +///
> +///  if (a == b && c == d)
> +///    statement; // BB3
> +///
> +///  Case 2: \param BB BB is on the then-path.
> +///
> +///             BB1
> +///          /      |
> +///         |      BB2
> +///         \    /    |  where BB1, BB2 contain conditional branches.
> +///  BB =>   BB3      |  BB3 contains unconditiona branch and corresponds
> +///           \     /    to \param BB.  BB4 is the merge.
> +///             BB4
> +///
> +///  Corresponding source code:
> +///
> +///  if (a == b || c == d)
> +///    statement;  // BB3
> +///
> +///  In both cases,  \param BB is the common successor of conditional branches.
> +///  In Case 1, \param BB (BB4) has an unconditional branch (BB3) as
> +///  its predecessor.  In Case 2, \param BB (BB3) only has conditional branches
> +///  as its predecessors.
> +///
> +bool FlattenCFGOpt::FlattenParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder,
> +                                         Pass *P) {
> +  PHINode *PHI = dyn_cast<PHINode>(BB->begin());
> +  if (PHI)
> +    return false; // For simplicity, avoid cases containing PHI nodes.
> +
> +  BasicBlock *LastCondBlock = NULL;
> +  BasicBlock *FirstCondBlock = NULL;
> +  BasicBlock *UnCondBlock = NULL;
> +  int Idx = -1;
> +
> +  // Check predecessors of \param BB.
> +  SmallPtrSet<BasicBlock *, 16> Preds(pred_begin(BB), pred_end(BB));
> +  for (SmallPtrSetIterator<BasicBlock *> PI = Preds.begin(), PE = Preds.end();
> +       PI != PE; ++PI) {
> +    BasicBlock *Pred = *PI;
> +    BranchInst *PBI = dyn_cast<BranchInst>(Pred->getTerminator());
> +
> +    // All predecessors should terminate with a branch.
> +    if (!PBI)
> +      return false;
> +
> +    BasicBlock *PP = Pred->getSinglePredecessor();
> +
> +    if (PBI->isUnconditional()) {
> +      // Case 1: Pred (BB3) is an unconditional block, it should
> +      // have a single predecessor (BB2) that is also a predecessor
> +      // of \param BB (BB4) and should not have address-taken.
> +      // There should exist only one such unconditional
> +      // branch among the predecessors.
> +      if (UnCondBlock || !PP || (Preds.count(PP) == 0) ||
> +          Pred->hasAddressTaken())
> +        return false;
> +
> +      UnCondBlock = Pred;
> +      continue;
> +    }
> +
> +    // Only conditional branches are allowed beyond this point.
> +    assert(PBI->isConditional());
> +
> +    // Condition's unique use should be the branch instruction.
> +    Value *PC = PBI->getCondition();
> +    if (!PC || !PC->hasOneUse())
> +      return false;
> +
> +    if (PP && Preds.count(PP)) {
> +      // These are internal condition blocks to be merged from, e.g.,
> +      // BB2 in both cases.
> +      // Should not be address-taken.
> +      if (Pred->hasAddressTaken())
> +        return false;
> +
> +      // Instructions in the internal condition blocks should be safe
> +      // to hoist up.
> +      for (BasicBlock::iterator BI = Pred->begin(), BE = PBI; BI != BE;) {
> +        Instruction *CI = BI++;
> +        if (isa<PHINode>(CI) || !isSafeToSpeculativelyExecute(CI))
> +          return false;
> +      }
> +    } else {
> +      // This is the condition block to be merged into, e.g. BB1 in
> +      // both cases.
> +      if (FirstCondBlock)
> +        return false;
> +      FirstCondBlock = Pred;
> +    }
> +
> +    // Find whether BB is uniformly on the true (or false) path
> +    // for all of its predecessors.
> +    BasicBlock *PS1 = PBI->getSuccessor(0);
> +    BasicBlock *PS2 = PBI->getSuccessor(1);
> +    BasicBlock *PS = (PS1 == BB) ? PS2 : PS1;
> +    int CIdx = (PS1 == BB) ? 0 : 1;
> +
> +    if (Idx == -1)
> +      Idx = CIdx;
> +    else if (CIdx != Idx)
> +      return false;
> +
> +    // PS is the successor which is not BB. Check successors to identify
> +    // the last conditional branch.
> +    if (Preds.count(PS) == 0) {
> +      // Case 2.
> +      LastCondBlock = Pred;
> +    } else {
> +      // Case 1
> +      BranchInst *BPS = dyn_cast<BranchInst>(PS->getTerminator());
> +      if (BPS && BPS->isUnconditional()) {
> +        // Case 1: PS(BB3) should be an unconditional branch.
> +        LastCondBlock = Pred;
> +      }
> +    }
> +  }
> +
> +  if (!FirstCondBlock || !LastCondBlock || (FirstCondBlock == LastCondBlock))
> +    return false;
> +
> +  TerminatorInst *TBB = LastCondBlock->getTerminator();
> +  BasicBlock *PS1 = TBB->getSuccessor(0);
> +  BasicBlock *PS2 = TBB->getSuccessor(1);
> +  BranchInst *PBI1 = dyn_cast<BranchInst>(PS1->getTerminator());
> +  BranchInst *PBI2 = dyn_cast<BranchInst>(PS2->getTerminator());
> +
> +  // If PS1 does not jump into PS2, but PS2 jumps into PS1,
> +  // attempt branch inversion.
> +  if (!PBI1 || !PBI1->isUnconditional() ||
> +      (PS1->getTerminator()->getSuccessor(0) != PS2)) {
> +    // Check whether PS2 jumps into PS1.
> +    if (!PBI2 || !PBI2->isUnconditional() ||
> +        (PS2->getTerminator()->getSuccessor(0) != PS1))
> +      return false;
> +
> +    // Do branch inversion.
> +    BasicBlock *CurrBlock = LastCondBlock;
> +    bool EverChanged = false;
> +    while (1) {
> +      BranchInst *BI = dyn_cast<BranchInst>(CurrBlock->getTerminator());
> +      CmpInst *CI = dyn_cast<CmpInst>(BI->getCondition());
> +      CmpInst::Predicate Predicate = CI->getPredicate();
> +      // Cannonicalize 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;
> +  }
> +
> +  // PS1 must have a conditional branch.
> +  if (!PBI1 || !PBI1->isUnconditional())
> +    return false;
> +
> +  // PS2 should not contain PHI node.
> +  PHI = dyn_cast<PHINode>(PS2->begin());
> +  if (PHI)
> +    return false;
> +
> +  // Do the transformation.
> +  BasicBlock *CB;
> +  BranchInst *PBI = dyn_cast<BranchInst>(FirstCondBlock->getTerminator());
> +  bool Iteration = true;
> +  BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
> +  BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
> +  Value *PC = PBI->getCondition();
> +
> +  do {
> +    CB = PBI->getSuccessor(1 - Idx);
> +    // Delete the conditional branch.
> +    FirstCondBlock->getInstList().pop_back();
> +    FirstCondBlock->getInstList()
> +        .splice(FirstCondBlock->end(), CB->getInstList());
> +    PBI = cast<BranchInst>(FirstCondBlock->getTerminator());
> +    Value *CC = PBI->getCondition();
> +    // Merge conditions.
> +    Builder.SetInsertPoint(PBI);
> +    Value *NC;
> +    if (Idx == 0)
> +      // Case 2, use parallel or.
> +      NC = Builder.CreateOr(PC, CC);
> +    else
> +      // Case 1, use parallel and.
> +      NC = Builder.CreateAnd(PC, CC);
> +
> +    PBI->replaceUsesOfWith(CC, NC);
> +    PC = NC;
> +    if (CB == LastCondBlock)
> +      Iteration = false;
> +    // Remove internal conditional branches.
> +    CB->dropAllReferences();
> +    // make CB unreachable and let downstream to delete the block.
> +    new UnreachableInst(CB->getContext(), CB);
> +  } while (Iteration);
> +
> +  Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt);
> +  DEBUG(dbgs() << "Use parallel and/or in:\n" << *FirstCondBlock);
> +  return true;
> +}
> +
> +/// Compare blocks from two if-regions, where \param Head1 is the entry of the
> +/// 1st if-region. \param Head2 is the entry of the 2nd if-region. \param
> +/// Block1 is a block in the 1st if-region to compare. \param Block2 is a block
> +//  in the 2nd if-region to compare.  \returns true if \param Block1 and \param
> +/// Block2 have identical instructions and do not have memory reference alias
> +/// with \param Head2.
> +///
> +bool FlattenCFGOpt::CompareIfRegionBlock(BasicBlock *Head1, BasicBlock *Head2,
> +                                         BasicBlock *Block1,
> +                                         BasicBlock *Block2) {
> +  TerminatorInst *PTI2 = Head2->getTerminator();
> +  Instruction *PBI2 = Head2->begin();
> +
> +  bool eq1 = (Block1 == Head1);
> +  bool eq2 = (Block2 == Head2);
> +  if (eq1 || eq2) {
> +    // An empty then-path or else-path.
> +    return (eq1 == eq2);
> +  }
> +
> +  // Check whether instructions in Block1 and Block2 are identical
> +  // and do not alias with instructions in Head2.
> +  BasicBlock::iterator iter1 = Block1->begin();
> +  BasicBlock::iterator end1 = Block1->getTerminator();
> +  BasicBlock::iterator iter2 = Block2->begin();
> +  BasicBlock::iterator end2 = Block2->getTerminator();
> +
> +  while (1) {
> +    if (iter1 == end1) {
> +      if (iter2 != end2)
> +        return false;
> +      break;
> +    }
> +
> +    if (!iter1->isIdenticalTo(iter2))
> +      return false;
> +
> +    // Illegal to remove instructions with side effects except
> +    // non-volatile stores.
> +    if (iter1->mayHaveSideEffects()) {
> +      Instruction *CurI = &*iter1;
> +      StoreInst *SI = dyn_cast<StoreInst>(CurI);
> +      if (!SI || SI->isVolatile())
> +        return false;
> +    }
> +
> +    // For simplicity and speed, data dependency check can be
> +    // avoided if read from memory doesn't exist.
> +    if (iter1->mayReadFromMemory())
> +      return false;
> +
> +    if (iter1->mayWriteToMemory()) {
> +      for (BasicBlock::iterator BI = PBI2, BE = PTI2; BI != BE; ++BI) {
> +        if (BI->mayReadFromMemory() || BI->mayWriteToMemory()) {
> +          // Check alias with Head2.
> +          if (!AA || AA->alias(iter1, BI))
> +            return false;
> +        }
> +      }
> +    }
> +    ++iter1;
> +    ++iter2;
> +  }
> +
> +  return true;
> +}
> +
> +/// 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
> +/// the two if-regions are merged.
> +///
> +/// From:
> +/// if (a)
> +///   statement;
> +/// if (b)
> +///   statement;
> +///
> +/// To:
> +/// if (a || b)
> +///   statement;
> +///
> +bool FlattenCFGOpt::MergeIfRegion(BasicBlock *BB, IRBuilder<> &Builder,
> +                                  Pass *P) {
> +  BasicBlock *IfTrue2, *IfFalse2;
> +  Value *IfCond2 = GetIfCondition(BB, IfTrue2, IfFalse2);
> +  Instruction *CInst2 = dyn_cast_or_null<Instruction>(IfCond2);
> +  if (!CInst2)
> +    return false;
> +
> +  BasicBlock *SecondEntryBlock = CInst2->getParent();
> +  if (SecondEntryBlock->hasAddressTaken())
> +    return false;
> +
> +  BasicBlock *IfTrue1, *IfFalse1;
> +  Value *IfCond1 = GetIfCondition(SecondEntryBlock, IfTrue1, IfFalse1);
> +  Instruction *CInst1 = dyn_cast_or_null<Instruction>(IfCond1);
> +  if (!CInst1)
> +    return false;
> +
> +  BasicBlock *FirstEntryBlock = CInst1->getParent();
> +
> +  // Either then-path or else-path should be empty.
> +  if ((IfTrue1 != FirstEntryBlock) && (IfFalse1 != FirstEntryBlock))
> +    return false;
> +  if ((IfTrue2 != SecondEntryBlock) && (IfFalse2 != SecondEntryBlock))
> +    return false;
> +
> +  TerminatorInst *PTI2 = SecondEntryBlock->getTerminator();
> +  Instruction *PBI2 = SecondEntryBlock->begin();
> +
> +  if (!CompareIfRegionBlock(FirstEntryBlock, SecondEntryBlock, IfTrue1,
> +                            IfTrue2))
> +    return false;
> +
> +  if (!CompareIfRegionBlock(FirstEntryBlock, SecondEntryBlock, IfFalse1,
> +                            IfFalse2))
> +    return false;
> +
> +  // Check whether \param SecondEntryBlock has side-effect and is safe to
> +  // speculate.
> +  for (BasicBlock::iterator BI = PBI2, BE = PTI2; BI != BE; ++BI) {
> +    Instruction *CI = BI;
> +    if (isa<PHINode>(CI) || CI->mayHaveSideEffects() ||
> +        !isSafeToSpeculativelyExecute(CI))
> +      return false;
> +  }
> +
> +  // Merge \param SecondEntryBlock into \param FirstEntryBlock.
> +  FirstEntryBlock->getInstList().pop_back();
> +  FirstEntryBlock->getInstList()
> +      .splice(FirstEntryBlock->end(), SecondEntryBlock->getInstList());
> +  BranchInst *PBI = dyn_cast<BranchInst>(FirstEntryBlock->getTerminator());
> +  Value *CC = PBI->getCondition();
> +  BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
> +  BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
> +  Builder.SetInsertPoint(PBI);
> +  Value *NC = Builder.CreateOr(CInst1, CC);
> +  PBI->replaceUsesOfWith(CC, NC);
> +  Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt);
> +
> +  // Remove IfTrue1
> +  if (IfTrue1 != FirstEntryBlock) {
> +    IfTrue1->dropAllReferences();
> +    IfTrue1->eraseFromParent();
> +  }
> +
> +  // Remove IfFalse1
> +  if (IfFalse1 != FirstEntryBlock) {
> +    IfFalse1->dropAllReferences();
> +    IfFalse1->eraseFromParent();
> +  }
> +
> +  // Remove \param SecondEntryBlock
> +  SecondEntryBlock->dropAllReferences();
> +  SecondEntryBlock->eraseFromParent();
> +  DEBUG(dbgs() << "If conditions merged into:\n" << *FirstEntryBlock);
> +  return true;
> +}
> +
> +bool FlattenCFGOpt::run(BasicBlock *BB) {
> +  bool Changed = false;
> +  assert(BB && BB->getParent() && "Block not embedded in function!");
> +  assert(BB->getTerminator() && "Degenerate basic block encountered!");
> +
> +  IRBuilder<> Builder(BB);
> +
> +  if (FlattenParallelAndOr(BB, Builder))
> +    return true;
> +
> +  if (MergeIfRegion(BB, Builder))
> +    return true;
> +
> +  return Changed;
> +}
> +
> +/// FlattenCFG - This function is used to flatten a CFG.  For
> +/// example, it uses parallel-and and parallel-or mode to collapse
> +//  if-conditions and merge if-regions with identical statements.
> +///
> +bool llvm::FlattenCFG(BasicBlock *BB, AliasAnalysis *AA) {
> +  return FlattenCFGOpt(AA).run(BB);
> +}
>
> Modified: llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp?rev=187764&r1=187763&r2=187764&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp (original)
> +++ llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp Mon Aug  5 21:43:45 2013
> @@ -19,7 +19,6 @@
>  #include "llvm/ADT/SmallPtrSet.h"
>  #include "llvm/ADT/SmallVector.h"
>  #include "llvm/ADT/Statistic.h"
> -#include "llvm/Analysis/AliasAnalysis.h"
>  #include "llvm/Analysis/InstructionSimplify.h"
>  #include "llvm/Analysis/TargetTransformInfo.h"
>  #include "llvm/Analysis/ValueTracking.h"
> @@ -66,10 +65,6 @@ static cl::opt<bool>
>  HoistCondStores("simplifycfg-hoist-cond-stores", cl::Hidden, cl::init(true),
>         cl::desc("Hoist conditional stores if an unconditional store preceeds"));
>
> -static cl::opt<bool>
> -ParallelAndOr("simplifycfg-parallel-and-or", cl::Hidden, cl::init(true),
> -              cl::desc("Use parallel-and-or mode for branch conditions"));
> -
>  STATISTIC(NumBitMaps, "Number of switch instructions turned into bitmaps");
>  STATISTIC(NumLookupTables, "Number of switch instructions turned into lookup tables");
>  STATISTIC(NumSinkCommons, "Number of common instructions sunk down to the end block");
> @@ -95,8 +90,6 @@ namespace {
>  class SimplifyCFGOpt {
>    const TargetTransformInfo &TTI;
>    const DataLayout *const TD;
> -  AliasAnalysis *AA;
> -
>    Value *isValueEqualityComparison(TerminatorInst *TI);
>    BasicBlock *GetValueEqualityComparisonCases(TerminatorInst *TI,
>                                 std::vector<ValueEqualityComparisonCase> &Cases);
> @@ -113,25 +106,10 @@ class SimplifyCFGOpt {
>    bool SimplifyIndirectBr(IndirectBrInst *IBI);
>    bool SimplifyUncondBranch(BranchInst *BI, IRBuilder <> &Builder);
>    bool SimplifyCondBranch(BranchInst *BI, IRBuilder <>&Builder);
> -  /// \brief Use parallel-and or parallel-or to generate conditions for
> -  /// conditional branches.
> -  bool SimplifyParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder, Pass *P = 0);
> -  /// \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);
> -  /// \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
> -  /// instructions, and have no memory reference alias with \p Head2.
> -  /// This is used as a legality check for merging if-regions.
> -  bool CompareIfRegionBlock(BasicBlock *Head1, BasicBlock *Head2,
> -                            BasicBlock *Block1, BasicBlock *Block2);
>
>  public:
> -  SimplifyCFGOpt(const TargetTransformInfo &TTI, const DataLayout *TD,
> -                 AliasAnalysis *AA)
> -      : TTI(TTI), TD(TD), AA(AA) {}
> +  SimplifyCFGOpt(const TargetTransformInfo &TTI, const DataLayout *TD)
> +      : TTI(TTI), TD(TD) {}
>    bool run(BasicBlock *BB);
>  };
>  }
> @@ -217,108 +195,6 @@ static void AddPredecessorToBlock(BasicB
>      PN->addIncoming(PN->getIncomingValueForBlock(ExistPred), NewPred);
>  }
>
> -
> -/// GetIfCondition - Given a basic block (BB) with two predecessors,
> -/// check to see if the merge at this block is due
> -/// to an "if condition".  If so, return the boolean condition that determines
> -/// which entry into BB will be taken.  Also, return by references the block
> -/// that will be entered from if the condition is true, and the block that will
> -/// be entered if the condition is false.
> -///
> -/// This does no checking to see if the true/false blocks have large or unsavory
> -/// instructions in them.
> -static Value *GetIfCondition(BasicBlock *BB, BasicBlock *&IfTrue,
> -                             BasicBlock *&IfFalse) {
> -  PHINode *SomePHI = dyn_cast<PHINode>(BB->begin());
> -  BasicBlock *Pred1 = NULL;
> -  BasicBlock *Pred2 = NULL;
> -
> -  if (SomePHI) {
> -    if (SomePHI->getNumIncomingValues() != 2)
> -      return NULL;
> -    Pred1 = SomePHI->getIncomingBlock(0);
> -    Pred2 = SomePHI->getIncomingBlock(1);
> -  } else {
> -    pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
> -    if (PI == PE) // No predecessor
> -      return NULL;
> -    Pred1 = *PI++;
> -    if (PI == PE) // Only one predecessor
> -      return NULL;
> -    Pred2 = *PI++;
> -    if (PI != PE) // More than two predecessors
> -      return NULL;
> -  }
> -
> -  // We can only handle branches.  Other control flow will be lowered to
> -  // branches if possible anyway.
> -  BranchInst *Pred1Br = dyn_cast<BranchInst>(Pred1->getTerminator());
> -  BranchInst *Pred2Br = dyn_cast<BranchInst>(Pred2->getTerminator());
> -  if (Pred1Br == 0 || Pred2Br == 0)
> -    return 0;
> -
> -  // Eliminate code duplication by ensuring that Pred1Br is conditional if
> -  // either are.
> -  if (Pred2Br->isConditional()) {
> -    // If both branches are conditional, we don't have an "if statement".  In
> -    // reality, we could transform this case, but since the condition will be
> -    // required anyway, we stand no chance of eliminating it, so the xform is
> -    // probably not profitable.
> -    if (Pred1Br->isConditional())
> -      return 0;
> -
> -    std::swap(Pred1, Pred2);
> -    std::swap(Pred1Br, Pred2Br);
> -  }
> -
> -  if (Pred1Br->isConditional()) {
> -    // The only thing we have to watch out for here is to make sure that Pred2
> -    // doesn't have incoming edges from other blocks.  If it does, the condition
> -    // doesn't dominate BB.
> -    if (Pred2->getSinglePredecessor() == 0)
> -      return 0;
> -
> -    // If we found a conditional branch predecessor, make sure that it branches
> -    // to BB and Pred2Br.  If it doesn't, this isn't an "if statement".
> -    if (Pred1Br->getSuccessor(0) == BB &&
> -        Pred1Br->getSuccessor(1) == Pred2) {
> -      IfTrue = Pred1;
> -      IfFalse = Pred2;
> -    } else if (Pred1Br->getSuccessor(0) == Pred2 &&
> -               Pred1Br->getSuccessor(1) == BB) {
> -      IfTrue = Pred2;
> -      IfFalse = Pred1;
> -    } else {
> -      // We know that one arm of the conditional goes to BB, so the other must
> -      // go somewhere unrelated, and this must not be an "if statement".
> -      return 0;
> -    }
> -
> -    return Pred1Br->getCondition();
> -  }
> -
> -  // Ok, if we got here, both predecessors end with an unconditional branch to
> -  // BB.  Don't panic!  If both blocks only have a single (identical)
> -  // predecessor, and THAT is a conditional branch, then we're all ok!
> -  BasicBlock *CommonPred = Pred1->getSinglePredecessor();
> -  if (CommonPred == 0 || CommonPred != Pred2->getSinglePredecessor())
> -    return 0;
> -
> -  // Otherwise, if this is a conditional branch, then we can use it!
> -  BranchInst *BI = dyn_cast<BranchInst>(CommonPred->getTerminator());
> -  if (BI == 0) return 0;
> -
> -  assert(BI->isConditional() && "Two successors but not conditional?");
> -  if (BI->getSuccessor(0) == Pred1) {
> -    IfTrue = Pred1;
> -    IfFalse = Pred2;
> -  } else {
> -    IfTrue = Pred2;
> -    IfFalse = Pred1;
> -  }
> -  return BI->getCondition();
> -}
> -
>  /// ComputeSpeculationCost - Compute an abstract "cost" of speculating the
>  /// given instruction, which is assumed to be safe to speculate. 1 means
>  /// cheap, 2 means less cheap, and UINT_MAX means prohibitively expensive.
> @@ -4102,386 +3978,6 @@ bool SimplifyCFGOpt::SimplifyCondBranch(
>    return false;
>  }
>
> -/// If \param [in] BB has more than one predecessor that is a conditional
> -/// branch, attempt to use parallel and/or for the branch condition. \returns
> -/// true on success.
> -///
> -/// Before:
> -///   ......
> -///   %cmp10 = fcmp une float %tmp1, %tmp2
> -///   br i1 %cmp1, label %if.then, label %lor.rhs
> -///
> -/// lor.rhs:
> -///   ......
> -///   %cmp11 = fcmp une float %tmp3, %tmp4
> -///   br i1 %cmp11, label %if.then, label %ifend
> -///
> -/// if.end:  // the merge block
> -///   ......
> -///
> -/// if.then: // has two predecessors, both of them contains conditional branch.
> -///   ......
> -///   br label %if.end;
> -///
> -/// After:
> -///  ......
> -///  %cmp10 = fcmp une float %tmp1, %tmp2
> -///  ......
> -///  %cmp11 = fcmp une float %tmp3, %tmp4
> -///  %cmp12 = or i1 %cmp10, %cmp11    // parallel-or mode.
> -///  br i1 %cmp12, label %if.then, label %ifend
> -///
> -///  if.end:
> -///    ......
> -///
> -///  if.then:
> -///    ......
> -///    br label %if.end;
> -///
> -///  Current implementation handles two cases.
> -///  Case 1: \param BB is on the else-path.
> -///
> -///          BB1
> -///        /     |
> -///       BB2    |
> -///      /   \   |
> -///     BB3   \  |     where, BB1, BB2 contain conditional branches.
> -///      \    |  /     BB3 contains unconditional branch.
> -///       \   | /      BB4 corresponds to \param BB which is also the merge.
> -///  BB => BB4
> -///
> -///
> -///  Corresponding source code:
> -///
> -///  if (a == b && c == d)
> -///    statement; // BB3
> -///
> -///  Case 2: \param BB BB is on the then-path.
> -///
> -///             BB1
> -///          /      |
> -///         |      BB2
> -///         \    /    |  where BB1, BB2 contain conditional branches.
> -///  BB =>   BB3      |  BB3 contains unconditiona branch and corresponds
> -///           \     /    to \param BB.  BB4 is the merge.
> -///             BB4
> -///
> -///  Corresponding source code:
> -///
> -///  if (a == b || c == d)
> -///    statement;  // BB3
> -///
> -///  In both cases,  \param BB is the common successor of conditional branches.
> -///  In Case 1, \param BB (BB4) has an unconditional branch (BB3) as
> -///  its predecessor.  In Case 2, \param BB (BB3) only has conditional branches
> -///  as its predecessors.
> -///
> -bool SimplifyCFGOpt::SimplifyParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder,
> -                                           Pass *P) {
> -  PHINode *PHI = dyn_cast<PHINode>(BB->begin());
> -  if (PHI)
> -    return false; // For simplicity, avoid cases containing PHI nodes.
> -
> -  BasicBlock *LastCondBlock = NULL;
> -  BasicBlock *FirstCondBlock = NULL;
> -  BasicBlock *UnCondBlock = NULL;
> -  int Idx = -1;
> -
> -  // Check predecessors of \param BB.
> -  SmallPtrSet<BasicBlock*, 16> Preds(pred_begin(BB), pred_end(BB));
> -  for (SmallPtrSetIterator<BasicBlock*> PI = Preds.begin(), PE = Preds.end();
> -       PI != PE; ++PI) {
> -    BasicBlock *Pred = *PI;
> -      BranchInst *PBI = dyn_cast<BranchInst>(Pred->getTerminator());
> -
> -    // All predecessors should terminate with a branch.
> -    if (!PBI)
> -      return false;
> -
> -    BasicBlock *PP = Pred->getSinglePredecessor();
> -
> -    if (PBI->isUnconditional()) {
> -      // Case 1: Pred (BB3) is an unconditional block, it should
> -      // have a single predecessor (BB2) that is also a predecessor
> -      // of \param BB (BB4) and should not have address-taken.
> -      // There should exist only one such unconditional
> -      // branch among the predecessors.
> -      if (UnCondBlock || !PP || (Preds.count(PP) == 0) ||
> -          Pred->hasAddressTaken())
> -        return false;
> -
> -      UnCondBlock = Pred;
> -      continue;
> -    }
> -
> -    // Only conditional branches are allowed beyond this point.
> -    assert(PBI->isConditional());
> -
> -    // Condition's unique use should be the branch instruction.
> -    Value *PC = PBI->getCondition();
> -    if (!PC || !PC->hasOneUse())
> -      return false;
> -
> -    if (PP && Preds.count(PP)) {
> -      // These are internal condition blocks to be merged from, e.g.,
> -      // BB2 in both cases.
> -      // Should not be address-taken.
> -      if (Pred->hasAddressTaken())
> -        return false;
> -
> -      // Instructions in the internal condition blocks should be safe
> -      // to hoist up.
> -      for (BasicBlock::iterator BI = Pred->begin(), BE = PBI; BI != BE;) {
> -        Instruction *CI = BI++;
> -        if (isa<PHINode>(CI) ||
> -            !isSafeToSpeculativelyExecute(CI))
> -          return false;
> -      }
> -    } else {
> -      // This is the condition block to be merged into, e.g. BB1 in
> -      // both cases.
> -      if (FirstCondBlock)
> -        return false;
> -      FirstCondBlock = Pred;
> -    }
> -
> -    // Find whether BB is uniformly on the true (or false) path
> -    // for all of its predecessors.
> -    BasicBlock *PS1 = PBI->getSuccessor(0);
> -    BasicBlock *PS2 = PBI->getSuccessor(1);
> -    BasicBlock *PS = (PS1 == BB) ? PS2 : PS1;
> -    int CIdx = (PS1 == BB) ? 0 : 1;
> -
> -    if (Idx == -1)
> -      Idx = CIdx;
> -    else if (CIdx != Idx)
> -      return false;
> -
> -    // PS is the successor which is not BB. Check successors to identify
> -    // the last conditional branch.
> -    if (Preds.count(PS) == 0) {
> -      // Case 2.
> -      // BB must have an unique successor.
> -      TerminatorInst *TBB = BB->getTerminator();
> -      if (TBB->getNumSuccessors() != 1)
> -        return false;
> -
> -      BasicBlock *SBB = TBB->getSuccessor(0);
> -      PHI = dyn_cast<PHINode>(SBB->begin());
> -      if (PHI)
> -        return false;
> -
> -      // PS (BB4) should be BB's successor.
> -      if (SBB != PS)
> -        return false;
> -      LastCondBlock = Pred;
> -    } else {
> -      BranchInst *BPS = dyn_cast<BranchInst>(PS->getTerminator());
> -      if (BPS && BPS->isUnconditional()) {
> -        // Case 1: PS(BB3) should be an unconditional branch.
> -        LastCondBlock = Pred;
> -      }
> -    }
> -  }
> -
> -  if (!FirstCondBlock || !LastCondBlock || (FirstCondBlock == LastCondBlock))
> -    return false;
> -
> -  // Do the transformation.
> -  BasicBlock *CB;
> -  bool Iteration = true;
> -  BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
> -  BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
> -  BranchInst *PBI = dyn_cast<BranchInst>(FirstCondBlock->getTerminator());
> -  Value *PC = PBI->getCondition();
> -  do {
> -    CB = PBI->getSuccessor(1 - Idx);
> -    // Delete the conditional branch.
> -    FirstCondBlock->getInstList().pop_back();
> -    FirstCondBlock->getInstList().splice(FirstCondBlock->end(), CB->getInstList());
> -    PBI = cast<BranchInst>(FirstCondBlock->getTerminator());
> -    Value *CC = PBI->getCondition();
> -    // Merge conditions.
> -    Builder.SetInsertPoint(PBI);
> -    Value *NC;
> -    if (Idx == 0)
> -      // Case 2, use parallel or.
> -      NC = Builder.CreateOr(PC, CC);
> -    else
> -      // Case 1, use parallel and.
> -      NC = Builder.CreateAnd(PC, CC);
> -
> -    PBI->replaceUsesOfWith(CC, NC);
> -    PC = NC;
> -    if (CB == LastCondBlock)
> -      Iteration = false;
> -    // Remove internal conditional branches.
> -    CB->dropAllReferences();
> -    // make CB unreachable and let downstream to delete the block.
> -    new UnreachableInst(CB->getContext(), CB);
> -  } while (Iteration);
> -  if (SaveInsertBB)
> -    Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt);
> -  DEBUG(dbgs() << "Use parallel and/or in:\n" << *FirstCondBlock);
> -  return true;
> -}
> -
> -/// Compare blocks from two if-regions, where \param Head1 is the entry of the
> -/// 1st if-region. \param Head2 is the entry of the 2nd if-region. \param
> -/// Block1 is a block in the 1st if-region to compare. \param Block2 is a block
> -//  in the 2nd if-region to compare.  \returns true if \param Block1 and \param
> -/// Block2 have identical instructions and do not have memory reference alias
> -/// with \param Head2.
> -///
> -bool SimplifyCFGOpt::CompareIfRegionBlock(BasicBlock *Head1, BasicBlock *Head2,
> -                                          BasicBlock *Block1, BasicBlock *Block2) {
> -  TerminatorInst *PTI2 = Head2->getTerminator();
> -  Instruction *PBI2 = Head2->begin();
> -
> -  bool eq1 = (Block1 == Head1);
> -  bool eq2 = (Block2 == Head2);
> -  if (eq1 || eq2) {
> -    // An empty then-path or else-path.
> -    return (eq1 == eq2);
> -  }
> -
> -  // Check whether instructions in Block1 and Block2 are identical
> -  // and do not alias with instructions in Head2.
> -  BasicBlock::iterator iter1 = Block1->begin();
> -  BasicBlock::iterator end1 = Block1->getTerminator();
> -  BasicBlock::iterator iter2 = Block2->begin();
> -  BasicBlock::iterator end2 = Block2->getTerminator();
> -
> -  while (1) {
> -    if (iter1 == end1) {
> -      if (iter2 != end2)
> -        return false;
> -      break;
> -    }
> -
> -    if (!iter1->isIdenticalTo(iter2))
> -      return false;
> -
> -    // Illegal to remove instructions with side effects except
> -    // non-volatile stores.
> -    if (iter1->mayHaveSideEffects()) {
> -      Instruction *CurI = &*iter1;
> -      StoreInst *SI = dyn_cast<StoreInst>(CurI);
> -      if (!SI || SI->isVolatile())
> -        return false;
> -    }
> -
> -    // For simplicity and speed, data dependency check can be
> -    // avoided if read from memory doesn't exist.
> -    if (iter1->mayReadFromMemory())
> -      return false;
> -
> -    if (iter1->mayWriteToMemory()) {
> -      for (BasicBlock::iterator BI = PBI2, BE = PTI2; BI != BE; ++BI) {
> -        if (BI->mayReadFromMemory() || BI->mayWriteToMemory()) {
> -          // Check alias with Head2.
> -          if (!AA || AA->alias(iter1, BI))
> -            return false;
> -        }
> -      }
> -    }
> -    ++iter1;
> -    ++iter2;
> -  }
> -
> -  return true;
> -}
> -
> -/// 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
> -/// the two if-regions are merged.
> -///
> -/// From:
> -/// if (a)
> -///   statement;
> -/// if (b)
> -///   statement;
> -///
> -/// To:
> -/// if (a || b)
> -///   statement;
> -///
> -bool SimplifyCFGOpt::MergeIfRegion(BasicBlock *BB, IRBuilder<> &Builder,
> -                                   Pass *P) {
> -  BasicBlock *IfTrue2, *IfFalse2;
> -  Value *IfCond2 = GetIfCondition(BB, IfTrue2, IfFalse2);
> -  Instruction *CInst2 = dyn_cast_or_null<Instruction>(IfCond2);
> -  if (!CInst2)
> -    return false;
> -
> -  BasicBlock *SecondEntryBlock = CInst2->getParent();
> -  if (SecondEntryBlock->hasAddressTaken())
> -    return false;
> -
> -  BasicBlock *IfTrue1, *IfFalse1;
> -  Value *IfCond1 = GetIfCondition(SecondEntryBlock, IfTrue1, IfFalse1);
> -  Instruction *CInst1 = dyn_cast_or_null<Instruction>(IfCond1);
> -  if (!CInst1)
> -    return false;
> -
> -  BasicBlock *FirstEntryBlock = CInst1->getParent();
> -
> -  // Either then-path or else-path should be empty.
> -  if ((IfTrue1 != FirstEntryBlock) && (IfFalse1 != FirstEntryBlock))
> -    return false;
> -  if ((IfTrue2 != SecondEntryBlock) && (IfFalse2 != SecondEntryBlock))
> -    return false;
> -
> -  TerminatorInst *PTI2 = SecondEntryBlock->getTerminator();
> -  Instruction *PBI2 = SecondEntryBlock->begin();
> -
> -  if (!CompareIfRegionBlock(FirstEntryBlock, SecondEntryBlock, IfTrue1, IfTrue2))
> -    return false;
> -
> -  if (!CompareIfRegionBlock(FirstEntryBlock, SecondEntryBlock, IfFalse1, IfFalse2))
> -    return false;
> -
> -  // Check whether \param SecondEntryBlock has side-effect and is safe to speculate.
> -  for (BasicBlock::iterator BI = PBI2, BE = PTI2; BI != BE; ++BI) {
> -    Instruction *CI = BI;
> -    if (isa<PHINode>(CI) || CI->mayHaveSideEffects() ||
> -        !isSafeToSpeculativelyExecute(CI))
> -      return false;
> -  }
> -
> -  // Merge \param SecondEntryBlock into \param FirstEntryBlock.
> -  FirstEntryBlock->getInstList().pop_back();
> -  FirstEntryBlock->getInstList().splice(FirstEntryBlock->end(), SecondEntryBlock->getInstList());
> -  BranchInst *PBI = dyn_cast<BranchInst>(FirstEntryBlock->getTerminator());
> -  Value *CC = PBI->getCondition();
> -  BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
> -  BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
> -  Builder.SetInsertPoint(PBI);
> -  Value *NC = Builder.CreateOr(CInst1, CC);
> -  PBI->replaceUsesOfWith(CC, NC);
> -  if (SaveInsertBB)
> -    Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt);
> -
> -  // Remove IfTrue1
> -  if (IfTrue1 != FirstEntryBlock) {
> -    IfTrue1->dropAllReferences();
> -    IfTrue1->eraseFromParent();
> -  }
> -
> -  // Remove IfFalse1
> -  if (IfFalse1 != FirstEntryBlock) {
> -    IfFalse1->dropAllReferences();
> -    IfFalse1->eraseFromParent();
> -  }
> -
> -  // Remove \param SecondEntryBlock
> -  SecondEntryBlock->dropAllReferences();
> -  SecondEntryBlock->eraseFromParent();
> -  DEBUG(dbgs() << "If conditions merged into:\n" << *FirstEntryBlock);
> -  return true;
> -}
> -
>  /// Check if passing a value to an instruction will cause undefined behavior.
>  static bool passingValueIsAlwaysUndefined(Value *V, Instruction *I) {
>    Constant *C = dyn_cast<Constant>(V);
> @@ -4584,11 +4080,6 @@ bool SimplifyCFGOpt::run(BasicBlock *BB)
>      return true;
>
>    IRBuilder<> Builder(BB);
> -  // Whether to optimize conditional branches.
> -  bool OptCB = (ParallelAndOr && AA && TTI.hasBranchDivergence());
> -
> -  if (OptCB && SimplifyParallelAndOr(BB, Builder))
> -    return true;
>
>    // If there is a trivial two-entry PHI node in this basic block, and we can
>    // eliminate it, do so now.
> @@ -4617,9 +4108,6 @@ bool SimplifyCFGOpt::run(BasicBlock *BB)
>      if (SimplifyIndirectBr(IBI)) return true;
>    }
>
> -  if (OptCB && MergeIfRegion(BB, Builder))
> -    return true;
> -
>    return Changed;
>  }
>
> @@ -4629,6 +4117,6 @@ bool SimplifyCFGOpt::run(BasicBlock *BB)
>  /// of the CFG.  It returns true if a modification was made.
>  ///
>  bool llvm::SimplifyCFG(BasicBlock *BB, const TargetTransformInfo &TTI,
> -                       const DataLayout *TD, AliasAnalysis *AA) {
> -  return SimplifyCFGOpt(TTI, TD, AA).run(BB);
> +                       const DataLayout *TD) {
> +  return SimplifyCFGOpt(TTI, TD).run(BB);
>  }
>
> Copied: llvm/trunk/test/CodeGen/R600/parallelandifcollapse.ll (from r187754, llvm/trunk/test/Transforms/SimplifyCFG/R600/parallelorifcollapse.ll)
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/R600/parallelandifcollapse.ll?p2=llvm/trunk/test/CodeGen/R600/parallelandifcollapse.ll&p1=llvm/trunk/test/Transforms/SimplifyCFG/R600/parallelorifcollapse.ll&r1=187754&r2=187764&rev=187764&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/SimplifyCFG/R600/parallelorifcollapse.ll (original)
> +++ llvm/trunk/test/CodeGen/R600/parallelandifcollapse.ll Mon Aug  5 21:43:45 2013
> @@ -1,14 +1,12 @@
>  ; Function Attrs: nounwind
> -; RUN: opt < %s -mtriple=r600-unknown-linux-gnu -optimizecfg -basicaa -S | FileCheck %s
> +; RUN: llc < %s -march=r600 -mcpu=redwood  | FileCheck %s
>  ;
> -; CFG optimization should use parallel-or mode to generate branch conditions and
> -; then merge if-regions with the same bodies, which should result in 2 branches.
> -; To see the assembly output without this transformation, remove -basicaa option.
> +; CFG flattening should use parallel-and mode to generate branch conditions and
> +; then merge if-regions with the same bodies.
>  ;
> -; CHECK: or i1
> -; CHECK-NEXT: br
> -; CHECK: br
> -; CHECK: ret
> +; CHECK: AND_INT
> +; CHECK-NEXT: AND_INT
> +; CHECK-NEXT: OR_INT
>  define void @_Z9chk1D_512v() #0 {
>  entry:
>    %a0 = alloca i32, align 4
>
> Copied: llvm/trunk/test/CodeGen/R600/parallelorifcollapse.ll (from r187754, llvm/trunk/test/Transforms/SimplifyCFG/R600/parallelandifcollapse.ll)
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/R600/parallelorifcollapse.ll?p2=llvm/trunk/test/CodeGen/R600/parallelorifcollapse.ll&p1=llvm/trunk/test/Transforms/SimplifyCFG/R600/parallelandifcollapse.ll&r1=187754&r2=187764&rev=187764&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/SimplifyCFG/R600/parallelandifcollapse.ll (original)
> +++ llvm/trunk/test/CodeGen/R600/parallelorifcollapse.ll Mon Aug  5 21:43:45 2013
> @@ -1,14 +1,12 @@
>  ; Function Attrs: nounwind
> -; RUN: opt < %s -mtriple=r600-unknown-linux-gnu -optimizecfg -basicaa -S | FileCheck %s
> +; RUN: llc < %s -march=r600 -mcpu=redwood  | FileCheck %s
>  ;
> -; CFG optimization should use parallel-and mode to generate branch conditions and
> -; then merge if-regions with the same bodies, which should result in 2 branches.
> -; To see the assembly output without this transformation, remove -basicaa option.
> -;
> -; CHECK: or i1
> -; CHECK-NEXT: br
> -; CHECK: br
> -; CHECK: ret
> +; CFG flattening should use parallel-or to generate branch conditions and
> +; then merge if-regions with the same bodies.
> +;
> +; CHECK: OR_INT
> +; CHECK-NEXT: OR_INT
> +; CHECK-NEXT: OR_INT
>  define void @_Z9chk1D_512v() #0 {
>  entry:
>    %a0 = alloca i32, align 4
>
> Modified: llvm/trunk/test/Transforms/SimplifyCFG/R600/lit.local.cfg
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/R600/lit.local.cfg?rev=187764&r1=187763&r2=187764&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/SimplifyCFG/R600/lit.local.cfg (original)
> +++ llvm/trunk/test/Transforms/SimplifyCFG/R600/lit.local.cfg Mon Aug  5 21:43:45 2013
> @@ -1,6 +0,0 @@
> -config.suffixes = ['.ll', '.c', '.cpp']
> -
> -targets = set(config.root.targets_to_build.split())
> -if not 'R600' in targets:
> -    config.unsupported = True
> -
>
> Modified: llvm/trunk/test/Transforms/SimplifyCFG/R600/parallelandifcollapse.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/R600/parallelandifcollapse.ll?rev=187764&r1=187763&r2=187764&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/SimplifyCFG/R600/parallelandifcollapse.ll (original)
> +++ llvm/trunk/test/Transforms/SimplifyCFG/R600/parallelandifcollapse.ll Mon Aug  5 21:43:45 2013
> @@ -1,63 +0,0 @@
> -; Function Attrs: nounwind
> -; RUN: opt < %s -mtriple=r600-unknown-linux-gnu -optimizecfg -basicaa -S | FileCheck %s
> -;
> -; CFG optimization should use parallel-and mode to generate branch conditions and
> -; then merge if-regions with the same bodies, which should result in 2 branches.
> -; To see the assembly output without this transformation, remove -basicaa option.
> -;
> -; CHECK: or i1
> -; CHECK-NEXT: br
> -; CHECK: br
> -; CHECK: ret
> -define void @_Z9chk1D_512v() #0 {
> -entry:
> -  %a0 = alloca i32, align 4
> -  %b0 = alloca i32, align 4
> -  %c0 = alloca i32, align 4
> -  %d0 = alloca i32, align 4
> -  %a1 = alloca i32, align 4
> -  %b1 = alloca i32, align 4
> -  %c1 = alloca i32, align 4
> -  %d1 = alloca i32, align 4
> -  %data = alloca i32, align 4
> -  %0 = load i32* %a0, align 4
> -  %1 = load i32* %b0, align 4
> -  %cmp = icmp ne i32 %0, %1
> -  br i1 %cmp, label %land.lhs.true, label %if.else
> -
> -land.lhs.true:                                    ; preds = %entry
> -  %2 = load i32* %c0, align 4
> -  %3 = load i32* %d0, align 4
> -  %cmp1 = icmp ne i32 %2, %3
> -  br i1 %cmp1, label %if.then, label %if.else
> -
> -if.then:                                          ; preds = %land.lhs.true
> -  br label %if.end
> -
> -if.else:                                          ; preds = %land.lhs.true, %entry
> -  store i32 1, i32* %data, align 4
> -  br label %if.end
> -
> -if.end:                                           ; preds = %if.else, %if.then
> -  %4 = load i32* %a1, align 4
> -  %5 = load i32* %b1, align 4
> -  %cmp2 = icmp ne i32 %4, %5
> -  br i1 %cmp2, label %land.lhs.true3, label %if.else6
> -
> -land.lhs.true3:                                   ; preds = %if.end
> -  %6 = load i32* %c1, align 4
> -  %7 = load i32* %d1, align 4
> -  %cmp4 = icmp ne i32 %6, %7
> -  br i1 %cmp4, label %if.then5, label %if.else6
> -
> -if.then5:                                         ; preds = %land.lhs.true3
> -  br label %if.end7
> -
> -if.else6:                                         ; preds = %land.lhs.true3, %if.end
> -  store i32 1, i32* %data, align 4
> -  br label %if.end7
> -
> -if.end7:                                          ; preds = %if.else6, %if.then5
> -  ret void
> -}
> -
>
> Modified: llvm/trunk/test/Transforms/SimplifyCFG/R600/parallelorifcollapse.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/R600/parallelorifcollapse.ll?rev=187764&r1=187763&r2=187764&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/SimplifyCFG/R600/parallelorifcollapse.ll (original)
> +++ llvm/trunk/test/Transforms/SimplifyCFG/R600/parallelorifcollapse.ll Mon Aug  5 21:43:45 2013
> @@ -1,56 +0,0 @@
> -; Function Attrs: nounwind
> -; RUN: opt < %s -mtriple=r600-unknown-linux-gnu -optimizecfg -basicaa -S | FileCheck %s
> -;
> -; CFG optimization should use parallel-or mode to generate branch conditions and
> -; then merge if-regions with the same bodies, which should result in 2 branches.
> -; To see the assembly output without this transformation, remove -basicaa option.
> -;
> -; CHECK: or i1
> -; CHECK-NEXT: br
> -; CHECK: br
> -; CHECK: ret
> -define void @_Z9chk1D_512v() #0 {
> -entry:
> -  %a0 = alloca i32, align 4
> -  %b0 = alloca i32, align 4
> -  %c0 = alloca i32, align 4
> -  %d0 = alloca i32, align 4
> -  %a1 = alloca i32, align 4
> -  %b1 = alloca i32, align 4
> -  %c1 = alloca i32, align 4
> -  %d1 = alloca i32, align 4
> -  %data = alloca i32, align 4
> -  %0 = load i32* %a0, align 4
> -  %1 = load i32* %b0, align 4
> -  %cmp = icmp ne i32 %0, %1
> -  br i1 %cmp, label %land.lhs.true, label %if.end
> -
> -land.lhs.true:                                    ; preds = %entry
> -  %2 = load i32* %c0, align 4
> -  %3 = load i32* %d0, align 4
> -  %cmp1 = icmp ne i32 %2, %3
> -  br i1 %cmp1, label %if.then, label %if.end
> -
> -if.then:                                          ; preds = %land.lhs.true
> -  store i32 1, i32* %data, align 4
> -  br label %if.end
> -
> -if.end:                                           ; preds = %if.then, %land.lhs.true, %entry
> -  %4 = load i32* %a1, align 4
> -  %5 = load i32* %b1, align 4
> -  %cmp2 = icmp ne i32 %4, %5
> -  br i1 %cmp2, label %land.lhs.true3, label %if.end6
> -
> -land.lhs.true3:                                   ; preds = %if.end
> -  %6 = load i32* %c1, align 4
> -  %7 = load i32* %d1, align 4
> -  %cmp4 = icmp ne i32 %6, %7
> -  br i1 %cmp4, label %if.then5, label %if.end6
> -
> -if.then5:                                         ; preds = %land.lhs.true3
> -  store i32 1, i32* %data, align 4
> -  br label %if.end6
> -
> -if.end6:                                          ; preds = %if.then5, %land.lhs.true3, %if.end
> -  ret void
> -}
>
> Modified: llvm/trunk/test/Transforms/SimplifyCFG/lit.local.cfg
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/lit.local.cfg?rev=187764&r1=187763&r2=187764&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/SimplifyCFG/lit.local.cfg (original)
> +++ llvm/trunk/test/Transforms/SimplifyCFG/lit.local.cfg Mon Aug  5 21:43:45 2013
> @@ -1 +0,0 @@
> -config.suffixes = ['.ll', '.c', '.cpp']
>
> Modified: llvm/trunk/tools/lto/LTOCodeGenerator.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/lto/LTOCodeGenerator.cpp?rev=187764&r1=187763&r2=187764&view=diff
> ==============================================================================
> --- llvm/trunk/tools/lto/LTOCodeGenerator.cpp (original)
> +++ llvm/trunk/tools/lto/LTOCodeGenerator.cpp Mon Aug  5 21:43:45 2013
> @@ -118,7 +118,7 @@ void LTOCodeGenerator::initializeLTOPass
>    initializeGVNPass(R);
>    initializeMemCpyOptPass(R);
>    initializeDCEPass(R);
> -  initializeCFGCanonicalizePass(R);
> +  initializeCFGSimplifyPassPass(R);
>  }
>
>  bool LTOCodeGenerator::addModule(LTOModule* mod, std::string& errMsg) {
>
>
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