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"
24 Statistic<> NumPromoted("mem2reg", "Number of alloca's promoted");
26 struct PromotePass : public FunctionPass {
27 // runOnFunction - To run this pass, first we calculate the alloca
28 // instructions that are safe for promotion, then we promote each one.
30 virtual bool runOnFunction(Function &F);
32 // getAnalysisUsage - We need dominance frontiers
34 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
35 AU.addRequired<DominatorTree>();
36 AU.addRequired<DominanceFrontier>();
37 AU.addRequired<TargetData>();
42 RegisterOpt<PromotePass> X("mem2reg", "Promote Memory to Register");
43 } // end of anonymous namespace
45 bool PromotePass::runOnFunction(Function &F) {
46 std::vector<AllocaInst*> Allocas;
47 const TargetData &TD = getAnalysis<TargetData>();
49 BasicBlock &BB = F.getEntryBlock(); // Get the entry node for the function
53 DominatorTree &DT = getAnalysis<DominatorTree>();
54 DominanceFrontier &DF = getAnalysis<DominanceFrontier>();
59 // Find allocas that are safe to promote, by looking at all instructions in
61 for (BasicBlock::iterator I = BB.begin(), E = --BB.end(); I != E; ++I)
62 if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) // Is it an alloca?
63 if (isAllocaPromotable(AI, TD))
64 Allocas.push_back(AI);
66 if (Allocas.empty()) break;
68 PromoteMemToReg(Allocas, DT, DF, TD);
69 NumPromoted += Allocas.size();
76 // createPromoteMemoryToRegister - Provide an entry point to create this pass.
78 Pass *createPromoteMemoryToRegister() {
79 return new PromotePass();