1 //===- Mem2Reg.cpp - The -mem2reg pass, a wrapper around the Utils lib ----===//
3 // This pass is a simple pass wrapper around the PromoteMemToReg function call
4 // exposed by the Utils library.
6 //===----------------------------------------------------------------------===//
8 #include "llvm/Transforms/Scalar.h"
9 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
10 #include "llvm/Analysis/Dominators.h"
11 #include "llvm/iMemory.h"
12 #include "llvm/Function.h"
13 #include "llvm/Target/TargetData.h"
14 #include "Support/Statistic.h"
17 Statistic<> NumPromoted("mem2reg", "Number of alloca's promoted");
19 struct PromotePass : public FunctionPass {
20 // runOnFunction - To run this pass, first we calculate the alloca
21 // instructions that are safe for promotion, then we promote each one.
23 virtual bool runOnFunction(Function &F);
25 // getAnalysisUsage - We need dominance frontiers
27 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
28 AU.addRequired<DominanceFrontier>();
29 AU.addRequired<TargetData>();
34 RegisterOpt<PromotePass> X("mem2reg", "Promote Memory to Register");
35 } // end of anonymous namespace
37 bool PromotePass::runOnFunction(Function &F) {
38 std::vector<AllocaInst*> Allocas;
39 const TargetData &TD = getAnalysis<TargetData>();
41 BasicBlock &BB = F.getEntryNode(); // Get the entry node for the function
43 // Find allocas that are safe to promote, by looking at all instructions in
45 for (BasicBlock::iterator I = BB.begin(), E = --BB.end(); I != E; ++I)
46 if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) // Is it an alloca?
47 if (isAllocaPromotable(AI, TD))
48 Allocas.push_back(AI);
50 if (!Allocas.empty()) {
51 PromoteMemToReg(Allocas, getAnalysis<DominanceFrontier>(), TD);
52 NumPromoted += Allocas.size();
58 // createPromoteMemoryToRegister - Provide an entry point to create this pass.
60 Pass *createPromoteMemoryToRegister() {
61 return new PromotePass();