125e9405272630204eb721d8b6ab47a5a25f24885Owen Anderson//===- CorrelatedValuePropagation.cpp - Propagate CFG-derived info --------===// 2a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson// 3a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson// The LLVM Compiler Infrastructure 4a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson// 5a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson// This file is distributed under the University of Illinois Open Source 6a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson// License. See LICENSE.TXT for details. 7a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson// 8a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson//===----------------------------------------------------------------------===// 9a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson// 1025e9405272630204eb721d8b6ab47a5a25f24885Owen Anderson// This file implements the Correlated Value Propagation pass. 11a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson// 12a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson//===----------------------------------------------------------------------===// 13a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson 1425e9405272630204eb721d8b6ab47a5a25f24885Owen Anderson#define DEBUG_TYPE "correlated-value-propagation" 15a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson#include "llvm/Transforms/Scalar.h" 16562b84b3aea359d1f918184e355da82bf05eb290Jay Foad#include "llvm/Constants.h" 17a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson#include "llvm/Function.h" 18a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson#include "llvm/Instructions.h" 19a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson#include "llvm/Pass.h" 20cdbd99262286e96729007ac535cd430ecb3d38acDuncan Sands#include "llvm/Analysis/InstructionSimplify.h" 21a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson#include "llvm/Analysis/LazyValueInfo.h" 22597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson#include "llvm/Support/CFG.h" 23a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson#include "llvm/Transforms/Utils/Local.h" 24f523b3e0878ea47e72b7d880b8fd18a33636fbdeOwen Anderson#include "llvm/ADT/Statistic.h" 25a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Andersonusing namespace llvm; 26a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson 271593dd6779d7ab1db13c44f32f987c32aff2b54bOwen AndersonSTATISTIC(NumPhis, "Number of phis propagated"); 281593dd6779d7ab1db13c44f32f987c32aff2b54bOwen AndersonSTATISTIC(NumSelects, "Number of selects propagated"); 291593dd6779d7ab1db13c44f32f987c32aff2b54bOwen AndersonSTATISTIC(NumMemAccess, "Number of memory access targets propagated"); 30597dad35b8b86c076dbbb0d095319c79de7806caOwen AndersonSTATISTIC(NumCmps, "Number of comparisons propagated"); 31a8eb6bb408e84ceb468ceb409f4c87308e67b9ebDuncan SandsSTATISTIC(NumDeadCases, "Number of switch cases removed"); 32f523b3e0878ea47e72b7d880b8fd18a33636fbdeOwen Anderson 33a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Andersonnamespace { 3425e9405272630204eb721d8b6ab47a5a25f24885Owen Anderson class CorrelatedValuePropagation : public FunctionPass { 35a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson LazyValueInfo *LVI; 3693f83deba1df95211898fe756758e81969955bd9Owen Anderson 37a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson bool processSelect(SelectInst *SI); 38a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson bool processPHI(PHINode *P); 391593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson bool processMemAccess(Instruction *I); 40597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson bool processCmp(CmpInst *C); 416f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands bool processSwitch(SwitchInst *SI); 4293f83deba1df95211898fe756758e81969955bd9Owen Anderson 43a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson public: 44a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson static char ID; 45081c34b725980f995be9080eaec24cd3dfaaf065Owen Anderson CorrelatedValuePropagation(): FunctionPass(ID) { 46081c34b725980f995be9080eaec24cd3dfaaf065Owen Anderson initializeCorrelatedValuePropagationPass(*PassRegistry::getPassRegistry()); 47081c34b725980f995be9080eaec24cd3dfaaf065Owen Anderson } 4893f83deba1df95211898fe756758e81969955bd9Owen Anderson 49a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson bool runOnFunction(Function &F); 5093f83deba1df95211898fe756758e81969955bd9Owen Anderson 51a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson virtual void getAnalysisUsage(AnalysisUsage &AU) const { 52a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson AU.addRequired<LazyValueInfo>(); 53a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson } 54a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson }; 55a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson} 56a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson 5725e9405272630204eb721d8b6ab47a5a25f24885Owen Andersonchar CorrelatedValuePropagation::ID = 0; 582ab36d350293c77fc8941ce1023e4899df7e3a82Owen AndersonINITIALIZE_PASS_BEGIN(CorrelatedValuePropagation, "correlated-propagation", 592ab36d350293c77fc8941ce1023e4899df7e3a82Owen Anderson "Value Propagation", false, false) 602ab36d350293c77fc8941ce1023e4899df7e3a82Owen AndersonINITIALIZE_PASS_DEPENDENCY(LazyValueInfo) 612ab36d350293c77fc8941ce1023e4899df7e3a82Owen AndersonINITIALIZE_PASS_END(CorrelatedValuePropagation, "correlated-propagation", 62ce665bd2e2b581ab0858d1afe359192bac96b868Owen Anderson "Value Propagation", false, false) 63a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson 64a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson// Public interface to the Value Propagation pass 6525e9405272630204eb721d8b6ab47a5a25f24885Owen AndersonPass *llvm::createCorrelatedValuePropagationPass() { 6625e9405272630204eb721d8b6ab47a5a25f24885Owen Anderson return new CorrelatedValuePropagation(); 67a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson} 68a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson 6925e9405272630204eb721d8b6ab47a5a25f24885Owen Andersonbool CorrelatedValuePropagation::processSelect(SelectInst *S) { 70a081d15b842e87c670260006eb17b5c1a826b5eeOwen Anderson if (S->getType()->isVectorTy()) return false; 711593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson if (isa<Constant>(S->getOperand(0))) return false; 7293f83deba1df95211898fe756758e81969955bd9Owen Anderson 73a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson Constant *C = LVI->getConstant(S->getOperand(0), S->getParent()); 74a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson if (!C) return false; 7593f83deba1df95211898fe756758e81969955bd9Owen Anderson 76a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson ConstantInt *CI = dyn_cast<ConstantInt>(C); 77a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson if (!CI) return false; 7893f83deba1df95211898fe756758e81969955bd9Owen Anderson 7986e8a700f516e8993417fb57d5386614b35c775dOwen Anderson Value *ReplaceWith = S->getOperand(1); 8086e8a700f516e8993417fb57d5386614b35c775dOwen Anderson Value *Other = S->getOperand(2); 8186e8a700f516e8993417fb57d5386614b35c775dOwen Anderson if (!CI->isOne()) std::swap(ReplaceWith, Other); 8286e8a700f516e8993417fb57d5386614b35c775dOwen Anderson if (ReplaceWith == S) ReplaceWith = UndefValue::get(S->getType()); 8386e8a700f516e8993417fb57d5386614b35c775dOwen Anderson 8486e8a700f516e8993417fb57d5386614b35c775dOwen Anderson S->replaceAllUsesWith(ReplaceWith); 85a081d15b842e87c670260006eb17b5c1a826b5eeOwen Anderson S->eraseFromParent(); 86a081d15b842e87c670260006eb17b5c1a826b5eeOwen Anderson 87f523b3e0878ea47e72b7d880b8fd18a33636fbdeOwen Anderson ++NumSelects; 8893f83deba1df95211898fe756758e81969955bd9Owen Anderson 89a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson return true; 90a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson} 91a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson 9225e9405272630204eb721d8b6ab47a5a25f24885Owen Andersonbool CorrelatedValuePropagation::processPHI(PHINode *P) { 93a081d15b842e87c670260006eb17b5c1a826b5eeOwen Anderson bool Changed = false; 9493f83deba1df95211898fe756758e81969955bd9Owen Anderson 95a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson BasicBlock *BB = P->getParent(); 96a081d15b842e87c670260006eb17b5c1a826b5eeOwen Anderson for (unsigned i = 0, e = P->getNumIncomingValues(); i < e; ++i) { 97a081d15b842e87c670260006eb17b5c1a826b5eeOwen Anderson Value *Incoming = P->getIncomingValue(i); 98a081d15b842e87c670260006eb17b5c1a826b5eeOwen Anderson if (isa<Constant>(Incoming)) continue; 9993f83deba1df95211898fe756758e81969955bd9Owen Anderson 100a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson Constant *C = LVI->getConstantOnEdge(P->getIncomingValue(i), 101a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson P->getIncomingBlock(i), 102a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson BB); 103a081d15b842e87c670260006eb17b5c1a826b5eeOwen Anderson if (!C) continue; 10493f83deba1df95211898fe756758e81969955bd9Owen Anderson 105a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson P->setIncomingValue(i, C); 106a081d15b842e87c670260006eb17b5c1a826b5eeOwen Anderson Changed = true; 107a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson } 108cdbd99262286e96729007ac535cd430ecb3d38acDuncan Sands 109cdbd99262286e96729007ac535cd430ecb3d38acDuncan Sands if (Value *V = SimplifyInstruction(P)) { 110cdbd99262286e96729007ac535cd430ecb3d38acDuncan Sands P->replaceAllUsesWith(V); 111a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson P->eraseFromParent(); 112a081d15b842e87c670260006eb17b5c1a826b5eeOwen Anderson Changed = true; 113a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson } 114cdbd99262286e96729007ac535cd430ecb3d38acDuncan Sands 115a8eb6bb408e84ceb468ceb409f4c87308e67b9ebDuncan Sands if (Changed) 116a8eb6bb408e84ceb468ceb409f4c87308e67b9ebDuncan Sands ++NumPhis; 11793f83deba1df95211898fe756758e81969955bd9Owen Anderson 118a081d15b842e87c670260006eb17b5c1a826b5eeOwen Anderson return Changed; 119a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson} 120a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson 1211593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Andersonbool CorrelatedValuePropagation::processMemAccess(Instruction *I) { 1221593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson Value *Pointer = 0; 1231593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson if (LoadInst *L = dyn_cast<LoadInst>(I)) 1241593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson Pointer = L->getPointerOperand(); 1251593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson else 1261593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson Pointer = cast<StoreInst>(I)->getPointerOperand(); 12793f83deba1df95211898fe756758e81969955bd9Owen Anderson 1281593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson if (isa<Constant>(Pointer)) return false; 12993f83deba1df95211898fe756758e81969955bd9Owen Anderson 1301593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson Constant *C = LVI->getConstant(Pointer, I->getParent()); 1311593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson if (!C) return false; 13293f83deba1df95211898fe756758e81969955bd9Owen Anderson 1331593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson ++NumMemAccess; 1341593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson I->replaceUsesOfWith(Pointer, C); 1351593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson return true; 1361593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson} 1371593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson 138597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson/// processCmp - If the value of this comparison could be determined locally, 139597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson/// constant propagation would already have figured it out. Instead, walk 140597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson/// the predecessors and statically evaluate the comparison based on information 141597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson/// available on that edge. If a given static evaluation is true on ALL 142597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson/// incoming edges, then it's true universally and we can simplify the compare. 143597dad35b8b86c076dbbb0d095319c79de7806caOwen Andersonbool CorrelatedValuePropagation::processCmp(CmpInst *C) { 144597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson Value *Op0 = C->getOperand(0); 145597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson if (isa<Instruction>(Op0) && 146597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson cast<Instruction>(Op0)->getParent() == C->getParent()) 147597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson return false; 14893f83deba1df95211898fe756758e81969955bd9Owen Anderson 149597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson Constant *Op1 = dyn_cast<Constant>(C->getOperand(1)); 150597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson if (!Op1) return false; 15193f83deba1df95211898fe756758e81969955bd9Owen Anderson 152597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson pred_iterator PI = pred_begin(C->getParent()), PE = pred_end(C->getParent()); 153597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson if (PI == PE) return false; 15493f83deba1df95211898fe756758e81969955bd9Owen Anderson 15593f83deba1df95211898fe756758e81969955bd9Owen Anderson LazyValueInfo::Tristate Result = LVI->getPredicateOnEdge(C->getPredicate(), 156597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson C->getOperand(0), Op1, *PI, C->getParent()); 157597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson if (Result == LazyValueInfo::Unknown) return false; 158597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson 159597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson ++PI; 160597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson while (PI != PE) { 16193f83deba1df95211898fe756758e81969955bd9Owen Anderson LazyValueInfo::Tristate Res = LVI->getPredicateOnEdge(C->getPredicate(), 162597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson C->getOperand(0), Op1, *PI, C->getParent()); 163597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson if (Res != Result) return false; 164597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson ++PI; 165597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson } 16693f83deba1df95211898fe756758e81969955bd9Owen Anderson 167597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson ++NumCmps; 16893f83deba1df95211898fe756758e81969955bd9Owen Anderson 169597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson if (Result == LazyValueInfo::True) 170597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson C->replaceAllUsesWith(ConstantInt::getTrue(C->getContext())); 171597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson else 172597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson C->replaceAllUsesWith(ConstantInt::getFalse(C->getContext())); 17393f83deba1df95211898fe756758e81969955bd9Owen Anderson 174597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson C->eraseFromParent(); 175597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson 176597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson return true; 177597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson} 178597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson 1796f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands/// processSwitch - Simplify a switch instruction by removing cases which can 1806f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands/// never fire. If the uselessness of a case could be determined locally then 1816f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands/// constant propagation would already have figured it out. Instead, walk the 1826f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands/// predecessors and statically evaluate cases based on information available 1836f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands/// on that edge. Cases that cannot fire no matter what the incoming edge can 1846f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands/// safely be removed. If a case fires on every incoming edge then the entire 1856f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands/// switch can be removed and replaced with a branch to the case destination. 1866f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sandsbool CorrelatedValuePropagation::processSwitch(SwitchInst *SI) { 1876f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands Value *Cond = SI->getCondition(); 1886f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands BasicBlock *BB = SI->getParent(); 1896f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands 1906f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // If the condition was defined in same block as the switch then LazyValueInfo 1916f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // currently won't say anything useful about it, though in theory it could. 1926f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands if (isa<Instruction>(Cond) && cast<Instruction>(Cond)->getParent() == BB) 1936f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands return false; 1946f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands 1956f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // If the switch is unreachable then trying to improve it is a waste of time. 1966f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands pred_iterator PB = pred_begin(BB), PE = pred_end(BB); 1976f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands if (PB == PE) return false; 1986f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands 1996f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // Analyse each switch case in turn. This is done in reverse order so that 2006f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // removing a case doesn't cause trouble for the iteration. 2016f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands bool Changed = false; 2023d3abe0852d5f499bed7ab014519dd582a0a795dStepan Dyatkovskiy for (SwitchInst::CaseIt CI = SI->case_end(), CE = SI->case_begin(); CI-- != CE; 2036f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands ) { 2046f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands ConstantInt *Case = CI.getCaseValue(); 2056f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands 2066f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // Check to see if the switch condition is equal to/not equal to the case 2076f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // value on every incoming edge, equal/not equal being the same each time. 2086f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands LazyValueInfo::Tristate State = LazyValueInfo::Unknown; 2096f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands for (pred_iterator PI = PB; PI != PE; ++PI) { 2106f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // Is the switch condition equal to the case value? 2116f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands LazyValueInfo::Tristate Value = LVI->getPredicateOnEdge(CmpInst::ICMP_EQ, 2126f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands Cond, Case, *PI, BB); 2136f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // Give up on this case if nothing is known. 2146f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands if (Value == LazyValueInfo::Unknown) { 2156f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands State = LazyValueInfo::Unknown; 2166f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands break; 2176f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands } 2186f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands 2196f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // If this was the first edge to be visited, record that all other edges 2206f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // need to give the same result. 2216f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands if (PI == PB) { 2226f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands State = Value; 2236f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands continue; 2246f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands } 2256f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands 2266f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // If this case is known to fire for some edges and known not to fire for 2276f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // others then there is nothing we can do - give up. 2286f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands if (Value != State) { 2296f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands State = LazyValueInfo::Unknown; 2306f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands break; 2316f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands } 2326f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands } 2336f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands 2346f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands if (State == LazyValueInfo::False) { 2356f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // This case never fires - remove it. 2366f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands CI.getCaseSuccessor()->removePredecessor(BB); 2376f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands SI->removeCase(CI); // Does not invalidate the iterator. 238a8eb6bb408e84ceb468ceb409f4c87308e67b9ebDuncan Sands ++NumDeadCases; 2396f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands Changed = true; 2406f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands } else if (State == LazyValueInfo::True) { 2416f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // This case always fires. Arrange for the switch to be turned into an 2426f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // unconditional branch by replacing the switch condition with the case 2436f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // value. 2446f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands SI->setCondition(Case); 245a8eb6bb408e84ceb468ceb409f4c87308e67b9ebDuncan Sands NumDeadCases += SI->getNumCases(); 2466f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands Changed = true; 2476f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands break; 2486f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands } 2496f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands } 2506f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands 2516f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands if (Changed) 2526f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // If the switch has been simplified to the point where it can be replaced 2536f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands // by a branch then do so now. 2546f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands ConstantFoldTerminator(BB); 2556f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands 2566f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands return Changed; 2576f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands} 2586f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands 25925e9405272630204eb721d8b6ab47a5a25f24885Owen Andersonbool CorrelatedValuePropagation::runOnFunction(Function &F) { 260a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson LVI = &getAnalysis<LazyValueInfo>(); 26193f83deba1df95211898fe756758e81969955bd9Owen Anderson 262869a144f4e53db38789e630fbd9cc57384685ce6Owen Anderson bool FnChanged = false; 26393f83deba1df95211898fe756758e81969955bd9Owen Anderson 2640995f20cfd97110cb842407b5757f217841b0defOwen Anderson for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI) { 265869a144f4e53db38789e630fbd9cc57384685ce6Owen Anderson bool BBChanged = false; 266a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson for (BasicBlock::iterator BI = FI->begin(), BE = FI->end(); BI != BE; ) { 267a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson Instruction *II = BI++; 2681593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson switch (II->getOpcode()) { 2691593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson case Instruction::Select: 2701593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson BBChanged |= processSelect(cast<SelectInst>(II)); 2711593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson break; 2721593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson case Instruction::PHI: 2731593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson BBChanged |= processPHI(cast<PHINode>(II)); 2741593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson break; 275597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson case Instruction::ICmp: 276597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson case Instruction::FCmp: 277597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson BBChanged |= processCmp(cast<CmpInst>(II)); 278597dad35b8b86c076dbbb0d095319c79de7806caOwen Anderson break; 2791593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson case Instruction::Load: 2801593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson case Instruction::Store: 2811593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson BBChanged |= processMemAccess(II); 2821593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson break; 2831593dd6779d7ab1db13c44f32f987c32aff2b54bOwen Anderson } 284a0b59f6bd23afaeba923b94f46838cffd5218a12Owen Anderson } 28593f83deba1df95211898fe756758e81969955bd9Owen Anderson 2866f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands Instruction *Term = FI->getTerminator(); 2876f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands switch (Term->getOpcode()) { 2886f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands case Instruction::Switch: 2896f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands BBChanged |= processSwitch(cast<SwitchInst>(Term)); 2906f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands break; 2916f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands } 2926f1d7994155c535455b7543e2af6dce5b65de37bDuncan Sands 293869a144f4e53db38789e630fbd9cc57384685ce6Owen Anderson FnChanged |= BBChanged; 2947c37f6d2d9d7fe0327e1de5e0dcda729a73d2a6fOwen Anderson } 29593f83deba1df95211898fe756758e81969955bd9Owen Anderson 296869a144f4e53db38789e630fbd9cc57384685ce6Owen Anderson return FnChanged; 2976cfabc7974c74f5a071f9f0621379902614d5179Benjamin Kramer} 298