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must be called in the pass's constructor. This function uses static dependency declarations to recursively initialize the pass's dependencies. Clients that only create passes through the createFooPass() APIs will require no changes. Clients that want to use the CommandLine options for passes will need to manually call the appropriate initialization functions in PassInitialization.h before parsing commandline arguments. I have tested this with all standard configurations of clang and llvm-gcc on Darwin. It is possible that there are problems with the static dependencies that will only be visible with non-standard options. If you encounter any crash in pass registration/creation, please send the testcase to me directly. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116820 91177308-0d34-0410-b5e6-96231b3b80d8
183 lines
6.3 KiB
C++
183 lines
6.3 KiB
C++
//===- PartialInlining.cpp - Inline parts of functions --------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass performs partial inlining, typically by inlining an if statement
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// that surrounds the body of the function.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "partialinlining"
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#include "llvm/Transforms/IPO.h"
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#include "llvm/Instructions.h"
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#include "llvm/Module.h"
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#include "llvm/Pass.h"
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#include "llvm/Analysis/Dominators.h"
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#include "llvm/Transforms/Utils/Cloning.h"
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#include "llvm/Transforms/Utils/FunctionUtils.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Support/CFG.h"
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using namespace llvm;
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STATISTIC(NumPartialInlined, "Number of functions partially inlined");
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namespace {
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struct PartialInliner : public ModulePass {
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virtual void getAnalysisUsage(AnalysisUsage &AU) const { }
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static char ID; // Pass identification, replacement for typeid
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PartialInliner() : ModulePass(ID) {
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initializePartialInlinerPass(*PassRegistry::getPassRegistry());
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}
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bool runOnModule(Module& M);
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private:
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Function* unswitchFunction(Function* F);
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};
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}
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char PartialInliner::ID = 0;
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INITIALIZE_PASS(PartialInliner, "partial-inliner",
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"Partial Inliner", false, false)
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ModulePass* llvm::createPartialInliningPass() { return new PartialInliner(); }
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Function* PartialInliner::unswitchFunction(Function* F) {
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// First, verify that this function is an unswitching candidate...
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BasicBlock* entryBlock = F->begin();
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BranchInst *BR = dyn_cast<BranchInst>(entryBlock->getTerminator());
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if (!BR || BR->isUnconditional())
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return 0;
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BasicBlock* returnBlock = 0;
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BasicBlock* nonReturnBlock = 0;
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unsigned returnCount = 0;
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for (succ_iterator SI = succ_begin(entryBlock), SE = succ_end(entryBlock);
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SI != SE; ++SI)
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if (isa<ReturnInst>((*SI)->getTerminator())) {
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returnBlock = *SI;
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returnCount++;
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} else
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nonReturnBlock = *SI;
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if (returnCount != 1)
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return 0;
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// Clone the function, so that we can hack away on it.
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ValueToValueMapTy VMap;
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Function* duplicateFunction = CloneFunction(F, VMap,
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/*ModuleLevelChanges=*/false);
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duplicateFunction->setLinkage(GlobalValue::InternalLinkage);
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F->getParent()->getFunctionList().push_back(duplicateFunction);
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BasicBlock* newEntryBlock = cast<BasicBlock>(VMap[entryBlock]);
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BasicBlock* newReturnBlock = cast<BasicBlock>(VMap[returnBlock]);
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BasicBlock* newNonReturnBlock = cast<BasicBlock>(VMap[nonReturnBlock]);
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// Go ahead and update all uses to the duplicate, so that we can just
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// use the inliner functionality when we're done hacking.
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F->replaceAllUsesWith(duplicateFunction);
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// Special hackery is needed with PHI nodes that have inputs from more than
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// one extracted block. For simplicity, just split the PHIs into a two-level
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// sequence of PHIs, some of which will go in the extracted region, and some
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// of which will go outside.
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BasicBlock* preReturn = newReturnBlock;
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newReturnBlock = newReturnBlock->splitBasicBlock(
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newReturnBlock->getFirstNonPHI());
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BasicBlock::iterator I = preReturn->begin();
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BasicBlock::iterator Ins = newReturnBlock->begin();
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while (I != preReturn->end()) {
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PHINode* OldPhi = dyn_cast<PHINode>(I);
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if (!OldPhi) break;
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PHINode* retPhi = PHINode::Create(OldPhi->getType(), "", Ins);
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OldPhi->replaceAllUsesWith(retPhi);
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Ins = newReturnBlock->getFirstNonPHI();
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retPhi->addIncoming(I, preReturn);
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retPhi->addIncoming(OldPhi->getIncomingValueForBlock(newEntryBlock),
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newEntryBlock);
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OldPhi->removeIncomingValue(newEntryBlock);
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++I;
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}
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newEntryBlock->getTerminator()->replaceUsesOfWith(preReturn, newReturnBlock);
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// Gather up the blocks that we're going to extract.
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std::vector<BasicBlock*> toExtract;
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toExtract.push_back(newNonReturnBlock);
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for (Function::iterator FI = duplicateFunction->begin(),
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FE = duplicateFunction->end(); FI != FE; ++FI)
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if (&*FI != newEntryBlock && &*FI != newReturnBlock &&
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&*FI != newNonReturnBlock)
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toExtract.push_back(FI);
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// The CodeExtractor needs a dominator tree.
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DominatorTree DT;
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DT.runOnFunction(*duplicateFunction);
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// Extract the body of the if.
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Function* extractedFunction = ExtractCodeRegion(DT, toExtract);
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InlineFunctionInfo IFI;
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// Inline the top-level if test into all callers.
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std::vector<User*> Users(duplicateFunction->use_begin(),
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duplicateFunction->use_end());
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for (std::vector<User*>::iterator UI = Users.begin(), UE = Users.end();
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UI != UE; ++UI)
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if (CallInst *CI = dyn_cast<CallInst>(*UI))
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InlineFunction(CI, IFI);
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else if (InvokeInst *II = dyn_cast<InvokeInst>(*UI))
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InlineFunction(II, IFI);
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// Ditch the duplicate, since we're done with it, and rewrite all remaining
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// users (function pointers, etc.) back to the original function.
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duplicateFunction->replaceAllUsesWith(F);
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duplicateFunction->eraseFromParent();
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++NumPartialInlined;
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return extractedFunction;
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}
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bool PartialInliner::runOnModule(Module& M) {
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std::vector<Function*> worklist;
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worklist.reserve(M.size());
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for (Module::iterator FI = M.begin(), FE = M.end(); FI != FE; ++FI)
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if (!FI->use_empty() && !FI->isDeclaration())
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worklist.push_back(&*FI);
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bool changed = false;
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while (!worklist.empty()) {
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Function* currFunc = worklist.back();
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worklist.pop_back();
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if (currFunc->use_empty()) continue;
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bool recursive = false;
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for (Function::use_iterator UI = currFunc->use_begin(),
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UE = currFunc->use_end(); UI != UE; ++UI)
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if (Instruction* I = dyn_cast<Instruction>(*UI))
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if (I->getParent()->getParent() == currFunc) {
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recursive = true;
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break;
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}
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if (recursive) continue;
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if (Function* newFunc = unswitchFunction(currFunc)) {
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worklist.push_back(newFunc);
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changed = true;
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}
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}
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return changed;
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}
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