PartialInlining.cpp [plain text]
#define DEBUG_TYPE "partialinlining"
#include "llvm/Transforms/IPO.h"
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/FunctionUtils.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/CFG.h"
using namespace llvm;
STATISTIC(NumPartialInlined, "Number of functions partially inlined");
namespace {
struct PartialInliner : public ModulePass {
virtual void getAnalysisUsage(AnalysisUsage &AU) const { }
static char ID; PartialInliner() : ModulePass(ID) {
initializePartialInlinerPass(*PassRegistry::getPassRegistry());
}
bool runOnModule(Module& M);
private:
Function* unswitchFunction(Function* F);
};
}
char PartialInliner::ID = 0;
INITIALIZE_PASS(PartialInliner, "partial-inliner",
"Partial Inliner", false, false)
ModulePass* llvm::createPartialInliningPass() { return new PartialInliner(); }
Function* PartialInliner::unswitchFunction(Function* F) {
BasicBlock* entryBlock = F->begin();
BranchInst *BR = dyn_cast<BranchInst>(entryBlock->getTerminator());
if (!BR || BR->isUnconditional())
return 0;
BasicBlock* returnBlock = 0;
BasicBlock* nonReturnBlock = 0;
unsigned returnCount = 0;
for (succ_iterator SI = succ_begin(entryBlock), SE = succ_end(entryBlock);
SI != SE; ++SI)
if (isa<ReturnInst>((*SI)->getTerminator())) {
returnBlock = *SI;
returnCount++;
} else
nonReturnBlock = *SI;
if (returnCount != 1)
return 0;
ValueToValueMapTy VMap;
Function* duplicateFunction = CloneFunction(F, VMap,
false);
duplicateFunction->setLinkage(GlobalValue::InternalLinkage);
F->getParent()->getFunctionList().push_back(duplicateFunction);
BasicBlock* newEntryBlock = cast<BasicBlock>(VMap[entryBlock]);
BasicBlock* newReturnBlock = cast<BasicBlock>(VMap[returnBlock]);
BasicBlock* newNonReturnBlock = cast<BasicBlock>(VMap[nonReturnBlock]);
F->replaceAllUsesWith(duplicateFunction);
BasicBlock* preReturn = newReturnBlock;
newReturnBlock = newReturnBlock->splitBasicBlock(
newReturnBlock->getFirstNonPHI());
BasicBlock::iterator I = preReturn->begin();
BasicBlock::iterator Ins = newReturnBlock->begin();
while (I != preReturn->end()) {
PHINode* OldPhi = dyn_cast<PHINode>(I);
if (!OldPhi) break;
PHINode* retPhi = PHINode::Create(OldPhi->getType(), 2, "", Ins);
OldPhi->replaceAllUsesWith(retPhi);
Ins = newReturnBlock->getFirstNonPHI();
retPhi->addIncoming(I, preReturn);
retPhi->addIncoming(OldPhi->getIncomingValueForBlock(newEntryBlock),
newEntryBlock);
OldPhi->removeIncomingValue(newEntryBlock);
++I;
}
newEntryBlock->getTerminator()->replaceUsesOfWith(preReturn, newReturnBlock);
std::vector<BasicBlock*> toExtract;
toExtract.push_back(newNonReturnBlock);
for (Function::iterator FI = duplicateFunction->begin(),
FE = duplicateFunction->end(); FI != FE; ++FI)
if (&*FI != newEntryBlock && &*FI != newReturnBlock &&
&*FI != newNonReturnBlock)
toExtract.push_back(FI);
DominatorTree DT;
DT.runOnFunction(*duplicateFunction);
Function* extractedFunction = ExtractCodeRegion(DT, toExtract);
InlineFunctionInfo IFI;
std::vector<User*> Users(duplicateFunction->use_begin(),
duplicateFunction->use_end());
for (std::vector<User*>::iterator UI = Users.begin(), UE = Users.end();
UI != UE; ++UI)
if (CallInst *CI = dyn_cast<CallInst>(*UI))
InlineFunction(CI, IFI);
else if (InvokeInst *II = dyn_cast<InvokeInst>(*UI))
InlineFunction(II, IFI);
duplicateFunction->replaceAllUsesWith(F);
duplicateFunction->eraseFromParent();
++NumPartialInlined;
return extractedFunction;
}
bool PartialInliner::runOnModule(Module& M) {
std::vector<Function*> worklist;
worklist.reserve(M.size());
for (Module::iterator FI = M.begin(), FE = M.end(); FI != FE; ++FI)
if (!FI->use_empty() && !FI->isDeclaration())
worklist.push_back(&*FI);
bool changed = false;
while (!worklist.empty()) {
Function* currFunc = worklist.back();
worklist.pop_back();
if (currFunc->use_empty()) continue;
bool recursive = false;
for (Function::use_iterator UI = currFunc->use_begin(),
UE = currFunc->use_end(); UI != UE; ++UI)
if (Instruction* I = dyn_cast<Instruction>(*UI))
if (I->getParent()->getParent() == currFunc) {
recursive = true;
break;
}
if (recursive) continue;
if (Function* newFunc = unswitchFunction(currFunc)) {
worklist.push_back(newFunc);
changed = true;
}
}
return changed;
}