1 //===- Mem2Reg.cpp - The -mem2reg pass, a wrapper around the Utils lib ----===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // 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 #define DEBUG_TYPE "mem2reg"
16 #include "llvm/Transforms/Scalar.h"
17 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
18 #include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
19 #include "llvm/IntrinsicInst.h"
20 #include "llvm/Analysis/Dominators.h"
21 #include "llvm/Instructions.h"
22 #include "llvm/Function.h"
23 #include "llvm/ADT/Statistic.h"
24 #include "llvm/Support/Compiler.h"
27 STATISTIC(NumPromoted, "Number of alloca's promoted");
30 struct VISIBILITY_HIDDEN PromotePass : public FunctionPass {
31 static char ID; // Pass identification, replacement for typeid
32 PromotePass() : FunctionPass(&ID) {}
34 // runOnFunction - To run this pass, first we calculate the alloca
35 // instructions that are safe for promotion, then we promote each one.
37 virtual bool runOnFunction(Function &F);
39 // getAnalysisUsage - We need dominance frontiers
41 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
42 AU.addRequired<DominatorTree>();
43 AU.addRequired<DominanceFrontier>();
45 // This is a cluster of orthogonal Transforms
46 AU.addPreserved<UnifyFunctionExitNodes>();
47 AU.addPreservedID(LowerSwitchID);
48 AU.addPreservedID(LowerInvokePassID);
49 AU.addPreservedID(LowerAllocationsID);
52 } // end of anonymous namespace
54 char PromotePass::ID = 0;
55 static RegisterPass<PromotePass> X("mem2reg", "Promote Memory to Register");
57 /// Remove the invalid or redundant debug information.
58 static void CleanDbgInfo(Function& F) {
59 std::vector<Instruction*> DeadDbgs;
60 for (Function::iterator BBI = F.begin(), BBE = F.end(); BBI != BBE; ++BBI) {
63 for (BasicBlock::iterator I = BBI->begin(), E = BBI->getTerminator();
65 BasicBlock::iterator NextI = I;
67 if (isa<DbgStopPointInst>(I) && isa<DbgStopPointInst>(NextI))
68 DeadDbgs.push_back(I);
69 else if (isa<DbgStopPointInst>(I) && isa<BranchInst>(NextI))
70 DeadDbgs.push_back(I);
74 while (!DeadDbgs.empty()) {
75 Instruction *Inst = DeadDbgs.back();
77 Inst->eraseFromParent();
81 bool PromotePass::runOnFunction(Function &F) {
82 std::vector<AllocaInst*> Allocas;
84 BasicBlock &BB = F.getEntryBlock(); // Get the entry node for the function
88 DominatorTree &DT = getAnalysis<DominatorTree>();
89 DominanceFrontier &DF = getAnalysis<DominanceFrontier>();
94 // Find allocas that are safe to promote, by looking at all instructions in
96 for (BasicBlock::iterator I = BB.begin(), E = --BB.end(); I != E; ++I)
97 if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) // Is it an alloca?
98 if (isAllocaPromotable(AI))
99 Allocas.push_back(AI);
101 if (Allocas.empty()) break;
103 PromoteMemToReg(Allocas, DT, DF);
105 NumPromoted += Allocas.size();
112 // Publically exposed interface to pass...
113 const PassInfo *const llvm::PromoteMemoryToRegisterID = &X;
114 // createPromoteMemoryToRegister - Provide an entry point to create this pass.
116 FunctionPass *llvm::createPromoteMemoryToRegisterPass() {
117 return new PromotePass();