//===- Mem2Reg.cpp - The -mem2reg pass, a wrapper around the Utils lib ----===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This pass is a simple pass wrapper around the PromoteMemToReg function call // exposed by the Utils library. // //===----------------------------------------------------------------------===// #include "llvm/Transforms/Scalar.h" #include "llvm/ADT/Statistic.h" #include "llvm/IR/Dominators.h" #include "llvm/IR/Function.h" #include "llvm/IR/Instructions.h" #include "llvm/Transforms/Utils/PromoteMemToReg.h" #include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h" using namespace llvm; #define DEBUG_TYPE "mem2reg" STATISTIC(NumPromoted, "Number of alloca's promoted"); namespace { struct PromotePass : public FunctionPass { static char ID; // Pass identification, replacement for typeid PromotePass() : FunctionPass(ID) { initializePromotePassPass(*PassRegistry::getPassRegistry()); } // runOnFunction - To run this pass, first we calculate the alloca // instructions that are safe for promotion, then we promote each one. // bool runOnFunction(Function &F) override; void getAnalysisUsage(AnalysisUsage &AU) const override { AU.addRequired<DominatorTreeWrapperPass>(); AU.setPreservesCFG(); // This is a cluster of orthogonal Transforms AU.addPreserved<UnifyFunctionExitNodes>(); AU.addPreservedID(LowerSwitchID); AU.addPreservedID(LowerInvokePassID); } }; } // end of anonymous namespace char PromotePass::ID = 0; INITIALIZE_PASS_BEGIN(PromotePass, "mem2reg", "Promote Memory to Register", false, false) INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) INITIALIZE_PASS_END(PromotePass, "mem2reg", "Promote Memory to Register", false, false) bool PromotePass::runOnFunction(Function &F) { std::vector<AllocaInst*> Allocas; BasicBlock &BB = F.getEntryBlock(); // Get the entry node for the function bool Changed = false; DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree(); while (1) { Allocas.clear(); // Find allocas that are safe to promote, by looking at all instructions in // the entry node for (BasicBlock::iterator I = BB.begin(), E = --BB.end(); I != E; ++I) if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) // Is it an alloca? if (isAllocaPromotable(AI)) Allocas.push_back(AI); if (Allocas.empty()) break; PromoteMemToReg(Allocas, DT); NumPromoted += Allocas.size(); Changed = true; } return Changed; } // createPromoteMemoryToRegister - Provide an entry point to create this pass. // FunctionPass *llvm::createPromoteMemoryToRegisterPass() { return new PromotePass(); }