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4ee451de36
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45418 91177308-0d34-0410-b5e6-96231b3b80d8
148 lines
5.1 KiB
C++
148 lines
5.1 KiB
C++
//===-- ExtractFunction.cpp - Function extraction pass --------------------===//
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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 extracts
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//
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//===----------------------------------------------------------------------===//
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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/Transforms/IPO.h"
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#include "llvm/Support/Compiler.h"
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using namespace llvm;
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namespace {
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/// @brief A pass to extract specific functions and their dependencies.
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class VISIBILITY_HIDDEN FunctionExtractorPass : public ModulePass {
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Function *Named;
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bool deleteFunc;
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bool reLink;
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public:
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static char ID; // Pass identification, replacement for typeid
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/// FunctionExtractorPass - If deleteFn is true, this pass deletes as the
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/// specified function. Otherwise, it deletes as much of the module as
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/// possible, except for the function specified.
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///
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explicit FunctionExtractorPass(Function *F = 0, bool deleteFn = true,
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bool relinkCallees = false)
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: ModulePass((intptr_t)&ID), Named(F), deleteFunc(deleteFn),
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reLink(relinkCallees) {}
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bool runOnModule(Module &M) {
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if (Named == 0) {
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Named = M.getFunction("main");
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if (Named == 0) return false; // No function to extract
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}
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if (deleteFunc)
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return deleteFunction();
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M.setModuleInlineAsm("");
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return isolateFunction(M);
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}
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bool deleteFunction() {
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// If we're in relinking mode, set linkage of all internal callees to
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// external. This will allow us extract function, and then - link
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// everything together
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if (reLink) {
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for (Function::iterator B = Named->begin(), BE = Named->end();
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B != BE; ++B) {
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for (BasicBlock::iterator I = B->begin(), E = B->end();
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I != E; ++I) {
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if (CallInst* callInst = dyn_cast<CallInst>(&*I)) {
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Function* Callee = callInst->getCalledFunction();
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if (Callee && Callee->hasInternalLinkage())
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Callee->setLinkage(GlobalValue::ExternalLinkage);
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}
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}
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}
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}
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Named->setLinkage(GlobalValue::ExternalLinkage);
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Named->deleteBody();
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assert(Named->isDeclaration() && "This didn't make the function external!");
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return true;
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}
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bool isolateFunction(Module &M) {
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// Make sure our result is globally accessible...
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Named->setLinkage(GlobalValue::ExternalLinkage);
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// Mark all global variables internal
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for (Module::global_iterator I = M.global_begin(), E = M.global_end(); I != E; ++I)
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if (!I->isDeclaration()) {
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I->setInitializer(0); // Make all variables external
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I->setLinkage(GlobalValue::ExternalLinkage);
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}
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// All of the functions may be used by global variables or the named
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// function. Loop through them and create a new, external functions that
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// can be "used", instead of ones with bodies.
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std::vector<Function*> NewFunctions;
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Function *Last = --M.end(); // Figure out where the last real fn is.
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for (Module::iterator I = M.begin(); ; ++I) {
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if (&*I != Named) {
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Function *New = new Function(I->getFunctionType(),
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GlobalValue::ExternalLinkage);
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New->setCallingConv(I->getCallingConv());
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New->setParamAttrs(I->getParamAttrs());
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if (I->hasCollector())
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New->setCollector(I->getCollector());
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// If it's not the named function, delete the body of the function
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I->dropAllReferences();
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M.getFunctionList().push_back(New);
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NewFunctions.push_back(New);
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New->takeName(I);
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}
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if (&*I == Last) break; // Stop after processing the last function
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}
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// Now that we have replacements all set up, loop through the module,
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// deleting the old functions, replacing them with the newly created
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// functions.
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if (!NewFunctions.empty()) {
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unsigned FuncNum = 0;
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Module::iterator I = M.begin();
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do {
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if (&*I != Named) {
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// Make everything that uses the old function use the new dummy fn
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I->replaceAllUsesWith(NewFunctions[FuncNum++]);
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Function *Old = I;
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++I; // Move the iterator to the new function
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// Delete the old function!
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M.getFunctionList().erase(Old);
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} else {
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++I; // Skip the function we are extracting
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}
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} while (&*I != NewFunctions[0]);
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}
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return true;
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}
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};
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char FunctionExtractorPass::ID = 0;
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RegisterPass<FunctionExtractorPass> X("extract", "Function Extractor");
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}
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ModulePass *llvm::createFunctionExtractionPass(Function *F, bool deleteFn,
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bool relinkCallees) {
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return new FunctionExtractorPass(F, deleteFn, relinkCallees);
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}
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