1 //===- Mem2Reg.cpp - The -mem2reg pass, a wrapper around the Utils lib ----===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This pass is a simple pass wrapper around the PromoteMemToReg function call
11 // exposed by the Utils library.
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Transforms/Scalar.h"
16 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
17 #include "llvm/Analysis/Dominators.h"
18 #include "llvm/iMemory.h"
19 #include "llvm/Function.h"
20 #include "llvm/Target/TargetData.h"
21 #include "Support/Statistic.h"
26 Statistic<> NumPromoted("mem2reg", "Number of alloca's promoted");
28 struct PromotePass : public FunctionPass {
29 // runOnFunction - To run this pass, first we calculate the alloca
30 // instructions that are safe for promotion, then we promote each one.
32 virtual bool runOnFunction(Function &F);
34 // getAnalysisUsage - We need dominance frontiers
36 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
37 AU.addRequired<DominatorTree>();
38 AU.addRequired<DominanceFrontier>();
39 AU.addRequired<TargetData>();
44 RegisterOpt<PromotePass> X("mem2reg", "Promote Memory to Register");
45 } // end of anonymous namespace
47 bool PromotePass::runOnFunction(Function &F) {
48 std::vector<AllocaInst*> Allocas;
49 const TargetData &TD = getAnalysis<TargetData>();
51 BasicBlock &BB = F.getEntryBlock(); // Get the entry node for the function
55 DominatorTree &DT = getAnalysis<DominatorTree>();
56 DominanceFrontier &DF = getAnalysis<DominanceFrontier>();
61 // Find allocas that are safe to promote, by looking at all instructions in
63 for (BasicBlock::iterator I = BB.begin(), E = --BB.end(); I != E; ++I)
64 if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) // Is it an alloca?
65 if (isAllocaPromotable(AI, TD))
66 Allocas.push_back(AI);
68 if (Allocas.empty()) break;
70 PromoteMemToReg(Allocas, DT, DF, TD);
71 NumPromoted += Allocas.size();
78 // createPromoteMemoryToRegister - Provide an entry point to create this pass.
80 Pass *createPromoteMemoryToRegister() {
81 return new PromotePass();
84 } // End llvm namespace