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 "Support/Statistic.h"
16 Statistic<> NumPromoted("mem2reg", "Number of alloca's promoted");
18 struct PromotePass : public FunctionPass {
19 // runOnFunction - To run this pass, first we calculate the alloca
20 // instructions that are safe for promotion, then we promote each one.
22 virtual bool runOnFunction(Function &F);
24 // getAnalysisUsage - We need dominance frontiers
26 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
27 AU.addRequired<DominanceFrontier>();
32 RegisterOpt<PromotePass> X("mem2reg", "Promote Memory to Register");
33 } // end of anonymous namespace
35 bool PromotePass::runOnFunction(Function &F) {
36 std::vector<AllocaInst*> Allocas;
38 BasicBlock &BB = F.getEntryNode(); // Get the entry node for the function
40 // Find allocas that are safe to promote, by looking at all instructions in
42 for (BasicBlock::iterator I = BB.begin(), E = --BB.end(); I != E; ++I)
43 if (AllocaInst *AI = dyn_cast<AllocaInst>(&*I)) // Is it an alloca?
44 if (isAllocaPromotable(AI))
45 Allocas.push_back(AI);
47 if (!Allocas.empty()) {
48 PromoteMemToReg(Allocas, getAnalysis<DominanceFrontier>());
49 NumPromoted += Allocas.size();
55 // createPromoteMemoryToRegister - Provide an entry point to create this pass.
57 Pass *createPromoteMemoryToRegister() {
58 return new PromotePass();