LowerSwitch.cpp revision 0f4c988a27d5723d723b7c8e7c4ca9fc6777f20d
114383485ac546e369b11797b42bc20831b6db57bChris Lattner//===- LowerSwitch.cpp - Eliminate Switch instructions --------------------===// 2fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman// 3b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// The LLVM Compiler Infrastructure 4b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// 54ee451de366474b9c228b4e5fa573795a715216dChris Lattner// This file is distributed under the University of Illinois Open Source 64ee451de366474b9c228b4e5fa573795a715216dChris Lattner// License. See LICENSE.TXT for details. 7fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman// 8b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell//===----------------------------------------------------------------------===// 914383485ac546e369b11797b42bc20831b6db57bChris Lattner// 10c86b67742a3298c0a5a715b57a64f11107b8a3f2Gordon Henriksen// The LowerSwitch transformation rewrites switch instructions with a sequence 11c86b67742a3298c0a5a715b57a64f11107b8a3f2Gordon Henriksen// of branches, which allows targets to get away with not implementing the 12c86b67742a3298c0a5a715b57a64f11107b8a3f2Gordon Henriksen// switch instruction until it is convenient. 1314383485ac546e369b11797b42bc20831b6db57bChris Lattner// 1414383485ac546e369b11797b42bc20831b6db57bChris Lattner//===----------------------------------------------------------------------===// 1514383485ac546e369b11797b42bc20831b6db57bChris Lattner 1614383485ac546e369b11797b42bc20831b6db57bChris Lattner#include "llvm/Transforms/Scalar.h" 178d89e7bdbcea38fe2ab3c85d91359712cd45714bChris Lattner#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h" 18ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner#include "llvm/Constants.h" 1914383485ac546e369b11797b42bc20831b6db57bChris Lattner#include "llvm/Function.h" 20d8e1eea678833cc2b15e4ea69a5a403ba9c3b013Misha Brukman#include "llvm/Instructions.h" 210a205a459884ec745df1c529396dd921f029dafdOwen Anderson#include "llvm/LLVMContext.h" 2214383485ac546e369b11797b42bc20831b6db57bChris Lattner#include "llvm/Pass.h" 23b61f2f061feefd79623fadd21eee4f195b0b8e56Dan Gohman#include "llvm/ADT/STLExtras.h" 24a4f0b3a084d120cfc5b5bb06f64b222f5cb72740Chris Lattner#include "llvm/Support/Compiler.h" 25f5a86f45e75ec744c203270ffa03659eb0a220c1Nick Lewycky#include "llvm/Support/Debug.h" 26944fac71e082cc2664cc71b4d3f6c72bab7143fbChris Lattner#include "llvm/Support/raw_ostream.h" 2720aa474f8fbebde588edc101b90e834df28ce4ceAlkis Evlogimenos#include <algorithm> 28d7456026629fc1760a45e6e955e9834246493147Chris Lattnerusing namespace llvm; 29d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 3014383485ac546e369b11797b42bc20831b6db57bChris Lattnernamespace { 3114383485ac546e369b11797b42bc20831b6db57bChris Lattner /// LowerSwitch Pass - Replace all SwitchInst instructions with chained branch 3214383485ac546e369b11797b42bc20831b6db57bChris Lattner /// instructions. Note that this cannot be a BasicBlock pass because it 3314383485ac546e369b11797b42bc20831b6db57bChris Lattner /// modifies the CFG! 346726b6d75a8b679068a58cb954ba97cf9d1690baNick Lewycky class LowerSwitch : public FunctionPass { 35ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner public: 36ecd94c804a563f2a86572dcf1d2e81f397e19daaNick Lewycky static char ID; // Pass identification, replacement for typeid 37ae73dc1448d25b02cabc7c64c86c64371453dda8Dan Gohman LowerSwitch() : FunctionPass(&ID) {} 38794fd75c67a2cdc128d67342c6d88a504d186896Devang Patel 398d89e7bdbcea38fe2ab3c85d91359712cd45714bChris Lattner virtual bool runOnFunction(Function &F); 40ed96fe8c79b36a38bd9280438656ee539276fb41Chris Lattner 418d89e7bdbcea38fe2ab3c85d91359712cd45714bChris Lattner virtual void getAnalysisUsage(AnalysisUsage &AU) const { 42bed2946a96ecb15b0b636fa74cb26ce61b1c648eAnton Korobeynikov // This is a cluster of orthogonal Transforms 438d89e7bdbcea38fe2ab3c85d91359712cd45714bChris Lattner AU.addPreserved<UnifyFunctionExitNodes>(); 448d89e7bdbcea38fe2ab3c85d91359712cd45714bChris Lattner AU.addPreservedID(PromoteMemoryToRegisterID); 45ed96fe8c79b36a38bd9280438656ee539276fb41Chris Lattner AU.addPreservedID(LowerInvokePassID); 468d89e7bdbcea38fe2ab3c85d91359712cd45714bChris Lattner } 47e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov 48e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov struct CaseRange { 49e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov Constant* Low; 50e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov Constant* High; 51e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov BasicBlock* BB; 52e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov 53c4558fde76bdb17bff28375fe20ee02e027095b8Jeff Cohen CaseRange() : Low(0), High(0), BB(0) { } 54c4558fde76bdb17bff28375fe20ee02e027095b8Jeff Cohen CaseRange(Constant* low, Constant* high, BasicBlock* bb) : 55c4558fde76bdb17bff28375fe20ee02e027095b8Jeff Cohen Low(low), High(high), BB(bb) { } 56e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov }; 57e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov 58e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov typedef std::vector<CaseRange> CaseVector; 59e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov typedef std::vector<CaseRange>::iterator CaseItr; 60ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner private: 6114383485ac546e369b11797b42bc20831b6db57bChris Lattner void processSwitchInst(SwitchInst *SI); 62ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 63ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner BasicBlock* switchConvert(CaseItr Begin, CaseItr End, Value* Val, 64ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner BasicBlock* OrigBlock, BasicBlock* Default); 65e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov BasicBlock* newLeafBlock(CaseRange& Leaf, Value* Val, 66ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner BasicBlock* OrigBlock, BasicBlock* Default); 67e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov unsigned Clusterify(CaseVector& Cases, SwitchInst *SI); 68ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner }; 69ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 70ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner /// The comparison function for sorting the switch case values in the vector. 71e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov /// WARNING: Case ranges should be disjoint! 72ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner struct CaseCmp { 73e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov bool operator () (const LowerSwitch::CaseRange& C1, 74e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov const LowerSwitch::CaseRange& C2) { 75ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 76e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov const ConstantInt* CI1 = cast<const ConstantInt>(C1.Low); 77e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov const ConstantInt* CI2 = cast<const ConstantInt>(C2.High); 78e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov return CI1->getValue().slt(CI2->getValue()); 79ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner } 8014383485ac546e369b11797b42bc20831b6db57bChris Lattner }; 8114383485ac546e369b11797b42bc20831b6db57bChris Lattner} 8214383485ac546e369b11797b42bc20831b6db57bChris Lattner 83844731a7f1909f55935e3514c9e713a62d67662eDan Gohmanchar LowerSwitch::ID = 0; 84844731a7f1909f55935e3514c9e713a62d67662eDan Gohmanstatic RegisterPass<LowerSwitch> 85844731a7f1909f55935e3514c9e713a62d67662eDan GohmanX("lowerswitch", "Lower SwitchInst's to branches"); 86844731a7f1909f55935e3514c9e713a62d67662eDan Gohman 87b3674e475389b72939bf90965790d63e9fa24b95Chris Lattner// Publically exposed interface to pass... 886ddba2b933645d308428201e942abe1274fa5085Dan Gohmanconst PassInfo *const llvm::LowerSwitchID = &X; 8914383485ac546e369b11797b42bc20831b6db57bChris Lattner// createLowerSwitchPass - Interface to this file... 90d7456026629fc1760a45e6e955e9834246493147Chris LattnerFunctionPass *llvm::createLowerSwitchPass() { 9114383485ac546e369b11797b42bc20831b6db57bChris Lattner return new LowerSwitch(); 9214383485ac546e369b11797b42bc20831b6db57bChris Lattner} 9314383485ac546e369b11797b42bc20831b6db57bChris Lattner 9414383485ac546e369b11797b42bc20831b6db57bChris Lattnerbool LowerSwitch::runOnFunction(Function &F) { 9514383485ac546e369b11797b42bc20831b6db57bChris Lattner bool Changed = false; 9614383485ac546e369b11797b42bc20831b6db57bChris Lattner 9714383485ac546e369b11797b42bc20831b6db57bChris Lattner for (Function::iterator I = F.begin(), E = F.end(); I != E; ) { 9814383485ac546e369b11797b42bc20831b6db57bChris Lattner BasicBlock *Cur = I++; // Advance over block so we don't traverse new blocks 9914383485ac546e369b11797b42bc20831b6db57bChris Lattner 10014383485ac546e369b11797b42bc20831b6db57bChris Lattner if (SwitchInst *SI = dyn_cast<SwitchInst>(Cur->getTerminator())) { 10114383485ac546e369b11797b42bc20831b6db57bChris Lattner Changed = true; 10214383485ac546e369b11797b42bc20831b6db57bChris Lattner processSwitchInst(SI); 10314383485ac546e369b11797b42bc20831b6db57bChris Lattner } 10414383485ac546e369b11797b42bc20831b6db57bChris Lattner } 10514383485ac546e369b11797b42bc20831b6db57bChris Lattner 10614383485ac546e369b11797b42bc20831b6db57bChris Lattner return Changed; 10714383485ac546e369b11797b42bc20831b6db57bChris Lattner} 10814383485ac546e369b11797b42bc20831b6db57bChris Lattner 109ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner// operator<< - Used for debugging purposes. 110ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner// 1111cd1d98232c3c3a0bd3810c3bf6c2572ea02f208Daniel Dunbarstatic raw_ostream& operator<<(raw_ostream &O, 112eb045ecba09bf606a7bcdda3edc52d43873561abMike Stump const LowerSwitch::CaseVector &C) ATTRIBUTE_USED; 11366ad89cebaecd7d88d9e723170c2b55fadd76b71Mike Stumpstatic raw_ostream& operator<<(raw_ostream &O, 1141cd1d98232c3c3a0bd3810c3bf6c2572ea02f208Daniel Dunbar const LowerSwitch::CaseVector &C) { 115ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner O << "["; 116ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 117e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov for (LowerSwitch::CaseVector::const_iterator B = C.begin(), 118d7456026629fc1760a45e6e955e9834246493147Chris Lattner E = C.end(); B != E; ) { 119e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov O << *B->Low << " -" << *B->High; 120ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner if (++B != E) O << ", "; 121ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner } 122ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 123ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner return O << "]"; 124ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner} 125e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov 126ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner// switchConvert - Convert the switch statement into a binary lookup of 127ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner// the case values. The function recursively builds this tree. 128ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner// 129ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris LattnerBasicBlock* LowerSwitch::switchConvert(CaseItr Begin, CaseItr End, 130ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner Value* Val, BasicBlock* OrigBlock, 131ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner BasicBlock* Default) 132ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner{ 133ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner unsigned Size = End - Begin; 134ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 135ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner if (Size == 1) 136ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner return newLeafBlock(*Begin, Val, OrigBlock, Default); 137ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 138ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner unsigned Mid = Size / 2; 139e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov std::vector<CaseRange> LHS(Begin, Begin + Mid); 1400f4c988a27d5723d723b7c8e7c4ca9fc6777f20dDavid Greene DEBUG(dbgs() << "LHS: " << LHS << "\n"); 141e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov std::vector<CaseRange> RHS(Begin + Mid, End); 1420f4c988a27d5723d723b7c8e7c4ca9fc6777f20dDavid Greene DEBUG(dbgs() << "RHS: " << RHS << "\n"); 143ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 144e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov CaseRange& Pivot = *(Begin + Mid); 1450f4c988a27d5723d723b7c8e7c4ca9fc6777f20dDavid Greene DEBUG(dbgs() << "Pivot ==> " 146944fac71e082cc2664cc71b4d3f6c72bab7143fbChris Lattner << cast<ConstantInt>(Pivot.Low)->getValue() << " -" 147f871ccb853a2ccbe8675c912330c041b318be8cdDan Gohman << cast<ConstantInt>(Pivot.High)->getValue() << "\n"); 148ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 149ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner BasicBlock* LBranch = switchConvert(LHS.begin(), LHS.end(), Val, 150ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner OrigBlock, Default); 151ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner BasicBlock* RBranch = switchConvert(RHS.begin(), RHS.end(), Val, 152ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner OrigBlock, Default); 153ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 154ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner // Create a new node that checks if the value is < pivot. Go to the 155ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner // left branch if it is and right branch if not. 156ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner Function* F = OrigBlock->getParent(); 1571d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson BasicBlock* NewNode = BasicBlock::Create(Val->getContext(), "NodeBlock"); 158261cdfbe5e6e11d56ca1c49a75f26fece3b139c8Chris Lattner Function::iterator FI = OrigBlock; 159261cdfbe5e6e11d56ca1c49a75f26fece3b139c8Chris Lattner F->getBasicBlockList().insert(++FI, NewNode); 160ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 1611c8a23c440b1665ba422778cdc74a0c59ecaf39eDan Gohman ICmpInst* Comp = new ICmpInst(ICmpInst::ICMP_SLT, 162333c40096561218bc3597cf153c0a3895274414cOwen Anderson Val, Pivot.Low, "Pivot"); 163ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner NewNode->getInstList().push_back(Comp); 164051a950000e21935165db56695e35bade668193bGabor Greif BranchInst::Create(LBranch, RBranch, Comp, NewNode); 165ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner return NewNode; 166ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner} 167ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 168ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner// newLeafBlock - Create a new leaf block for the binary lookup tree. It 169ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner// checks if the switch's value == the case's value. If not, then it 170ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner// jumps to the default branch. At this point in the tree, the value 171ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner// can't be another valid case value, so the jump to the "default" branch 172ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner// is warranted. 173ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner// 174e2ff29c17c1a7c121e22789cf1654d923467b472Anton KorobeynikovBasicBlock* LowerSwitch::newLeafBlock(CaseRange& Leaf, Value* Val, 175ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner BasicBlock* OrigBlock, 176ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner BasicBlock* Default) 177ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner{ 178ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner Function* F = OrigBlock->getParent(); 1791d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson BasicBlock* NewLeaf = BasicBlock::Create(Val->getContext(), "LeafBlock"); 180261cdfbe5e6e11d56ca1c49a75f26fece3b139c8Chris Lattner Function::iterator FI = OrigBlock; 181261cdfbe5e6e11d56ca1c49a75f26fece3b139c8Chris Lattner F->getBasicBlockList().insert(++FI, NewLeaf); 182ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 183e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov // Emit comparison 184e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov ICmpInst* Comp = NULL; 185e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov if (Leaf.Low == Leaf.High) { 186e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov // Make the seteq instruction... 187333c40096561218bc3597cf153c0a3895274414cOwen Anderson Comp = new ICmpInst(*NewLeaf, ICmpInst::ICMP_EQ, Val, 188333c40096561218bc3597cf153c0a3895274414cOwen Anderson Leaf.Low, "SwitchLeaf"); 189e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov } else { 190e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov // Make range comparison 191e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov if (cast<ConstantInt>(Leaf.Low)->isMinValue(true /*isSigned*/)) { 192e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov // Val >= Min && Val <= Hi --> Val <= Hi 193333c40096561218bc3597cf153c0a3895274414cOwen Anderson Comp = new ICmpInst(*NewLeaf, ICmpInst::ICMP_SLE, Val, Leaf.High, 194333c40096561218bc3597cf153c0a3895274414cOwen Anderson "SwitchLeaf"); 195e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov } else if (cast<ConstantInt>(Leaf.Low)->isZero()) { 196e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov // Val >= 0 && Val <= Hi --> Val <=u Hi 197333c40096561218bc3597cf153c0a3895274414cOwen Anderson Comp = new ICmpInst(*NewLeaf, ICmpInst::ICMP_ULE, Val, Leaf.High, 198333c40096561218bc3597cf153c0a3895274414cOwen Anderson "SwitchLeaf"); 199e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov } else { 200e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov // Emit V-Lo <=u Hi-Lo 201baf3c404409d5e47b13984a7f95bfbd6d1f2e79eOwen Anderson Constant* NegLo = ConstantExpr::getNeg(Leaf.Low); 2027cbd8a3e92221437048b484d5ef9c0a22d0f8c58Gabor Greif Instruction* Add = BinaryOperator::CreateAdd(Val, NegLo, 203e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov Val->getName()+".off", 204e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov NewLeaf); 205baf3c404409d5e47b13984a7f95bfbd6d1f2e79eOwen Anderson Constant *UpperBound = ConstantExpr::getAdd(NegLo, Leaf.High); 206333c40096561218bc3597cf153c0a3895274414cOwen Anderson Comp = new ICmpInst(*NewLeaf, ICmpInst::ICMP_ULE, Add, UpperBound, 207333c40096561218bc3597cf153c0a3895274414cOwen Anderson "SwitchLeaf"); 208e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov } 209e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov } 210ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 211ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner // Make the conditional branch... 212e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov BasicBlock* Succ = Leaf.BB; 213051a950000e21935165db56695e35bade668193bGabor Greif BranchInst::Create(Succ, Default, Comp, NewLeaf); 214ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 215ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner // If there were any PHI nodes in this successor, rewrite one entry 216ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner // from OrigBlock to come from NewLeaf. 2172da5c3dda6f5b9c4ec6d55008d33327764364bd4Reid Spencer for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) { 2182da5c3dda6f5b9c4ec6d55008d33327764364bd4Reid Spencer PHINode* PN = cast<PHINode>(I); 219e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov // Remove all but one incoming entries from the cluster 220e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov uint64_t Range = cast<ConstantInt>(Leaf.High)->getSExtValue() - 221e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov cast<ConstantInt>(Leaf.Low)->getSExtValue(); 222e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov for (uint64_t j = 0; j < Range; ++j) { 223e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov PN->removeIncomingValue(OrigBlock); 224e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov } 225e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov 226ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner int BlockIdx = PN->getBasicBlockIndex(OrigBlock); 227ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner assert(BlockIdx != -1 && "Switch didn't go to this successor??"); 228ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner PN->setIncomingBlock((unsigned)BlockIdx, NewLeaf); 229ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner } 230ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 231ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner return NewLeaf; 232ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner} 233ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 234e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov// Clusterify - Transform simple list of Cases into list of CaseRange's 235e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikovunsigned LowerSwitch::Clusterify(CaseVector& Cases, SwitchInst *SI) { 236e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov unsigned numCmps = 0; 237e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov 238e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov // Start with "simple" cases 239e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov for (unsigned i = 1; i < SI->getNumSuccessors(); ++i) 240e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov Cases.push_back(CaseRange(SI->getSuccessorValue(i), 241e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov SI->getSuccessorValue(i), 242e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov SI->getSuccessor(i))); 243111c4f897eb9a42eac6aceea830b8e76058afd73Dan Gohman std::sort(Cases.begin(), Cases.end(), CaseCmp()); 244e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov 245e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov // Merge case into clusters 246e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov if (Cases.size()>=2) 2477896c9f436a4eda5ec15e882a7505ba482a2fcd0Chris Lattner for (CaseItr I=Cases.begin(), J=llvm::next(Cases.begin()); J!=Cases.end(); ) { 248e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov int64_t nextValue = cast<ConstantInt>(J->Low)->getSExtValue(); 249e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov int64_t currentValue = cast<ConstantInt>(I->High)->getSExtValue(); 250e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov BasicBlock* nextBB = J->BB; 251e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov BasicBlock* currentBB = I->BB; 252e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov 253e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov // If the two neighboring cases go to the same destination, merge them 254e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov // into a single case. 255e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov if ((nextValue-currentValue==1) && (currentBB == nextBB)) { 256e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov I->High = J->High; 257e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov J = Cases.erase(J); 258e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov } else { 259e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov I = J++; 260e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov } 261e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov } 262e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov 263e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov for (CaseItr I=Cases.begin(), E=Cases.end(); I!=E; ++I, ++numCmps) { 264e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov if (I->Low != I->High) 265e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov // A range counts double, since it requires two compares. 266e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov ++numCmps; 267e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov } 268e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov 269e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov return numCmps; 270e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov} 271e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov 27214383485ac546e369b11797b42bc20831b6db57bChris Lattner// processSwitchInst - Replace the specified switch instruction with a sequence 273ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner// of chained if-then insts in a balanced binary search. 27414383485ac546e369b11797b42bc20831b6db57bChris Lattner// 27514383485ac546e369b11797b42bc20831b6db57bChris Lattnervoid LowerSwitch::processSwitchInst(SwitchInst *SI) { 27614383485ac546e369b11797b42bc20831b6db57bChris Lattner BasicBlock *CurBlock = SI->getParent(); 27714383485ac546e369b11797b42bc20831b6db57bChris Lattner BasicBlock *OrigBlock = CurBlock; 27814383485ac546e369b11797b42bc20831b6db57bChris Lattner Function *F = CurBlock->getParent(); 27914383485ac546e369b11797b42bc20831b6db57bChris Lattner Value *Val = SI->getOperand(0); // The value we are switching on... 280ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner BasicBlock* Default = SI->getDefaultDest(); 28114383485ac546e369b11797b42bc20831b6db57bChris Lattner 28244bb541c011bcae84759ed194ec7cb4139775fcbChris Lattner // If there is only the default destination, don't bother with the code below. 28344bb541c011bcae84759ed194ec7cb4139775fcbChris Lattner if (SI->getNumOperands() == 2) { 284051a950000e21935165db56695e35bade668193bGabor Greif BranchInst::Create(SI->getDefaultDest(), CurBlock); 285bf9eaddfb0642e49bc2f3835765a9782ff48c76eChris Lattner CurBlock->getInstList().erase(SI); 28644bb541c011bcae84759ed194ec7cb4139775fcbChris Lattner return; 28744bb541c011bcae84759ed194ec7cb4139775fcbChris Lattner } 28844bb541c011bcae84759ed194ec7cb4139775fcbChris Lattner 289ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner // Create a new, empty default block so that the new hierarchy of 290ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner // if-then statements go to this and the PHI nodes are happy. 2911d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson BasicBlock* NewDefault = BasicBlock::Create(SI->getContext(), "NewDefault"); 292ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner F->getBasicBlockList().insert(Default, NewDefault); 29314383485ac546e369b11797b42bc20831b6db57bChris Lattner 294051a950000e21935165db56695e35bade668193bGabor Greif BranchInst::Create(Default, NewDefault); 29520af3222da5dea65246ecd9f64a53ea3e3cc1b8aChris Lattner 296ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner // If there is an entry in any PHI nodes for the default edge, make sure 297ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner // to update them as well. 2982da5c3dda6f5b9c4ec6d55008d33327764364bd4Reid Spencer for (BasicBlock::iterator I = Default->begin(); isa<PHINode>(I); ++I) { 2992da5c3dda6f5b9c4ec6d55008d33327764364bd4Reid Spencer PHINode *PN = cast<PHINode>(I); 300ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner int BlockIdx = PN->getBasicBlockIndex(OrigBlock); 301ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner assert(BlockIdx != -1 && "Switch didn't go to this successor??"); 302ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner PN->setIncomingBlock((unsigned)BlockIdx, NewDefault); 30314383485ac546e369b11797b42bc20831b6db57bChris Lattner } 30414383485ac546e369b11797b42bc20831b6db57bChris Lattner 305e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov // Prepare cases vector. 306e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov CaseVector Cases; 307e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov unsigned numCmps = Clusterify(Cases, SI); 308ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 3090f4c988a27d5723d723b7c8e7c4ca9fc6777f20dDavid Greene DEBUG(dbgs() << "Clusterify finished. Total clusters: " << Cases.size() 3106c1980b3357207c4d756255bc5e32323eac278dcDan Gohman << ". Total compares: " << numCmps << "\n"); 3110f4c988a27d5723d723b7c8e7c4ca9fc6777f20dDavid Greene DEBUG(dbgs() << "Cases: " << Cases << "\n"); 31202efa786d40fabae6dbbb3de5ab057359701e337Mike Stump (void)numCmps; 313e2ff29c17c1a7c121e22789cf1654d923467b472Anton Korobeynikov 314ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner BasicBlock* SwitchBlock = switchConvert(Cases.begin(), Cases.end(), Val, 315ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner OrigBlock, NewDefault); 316ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 317ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner // Branch to our shiny new if-then stuff... 318051a950000e21935165db56695e35bade668193bGabor Greif BranchInst::Create(SwitchBlock, OrigBlock); 319ebbc1a5aa0c37ab29d14ae56c176b3bfd25658cbChris Lattner 32014383485ac546e369b11797b42bc20831b6db57bChris Lattner // We are now done with the switch instruction, delete it. 321bf9eaddfb0642e49bc2f3835765a9782ff48c76eChris Lattner CurBlock->getInstList().erase(SI); 32214383485ac546e369b11797b42bc20831b6db57bChris Lattner} 323