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the section or the visibility from one global value to another: copyAttributesFrom. This is particularly useful for duplicating functions: previously this was done by explicitly copying each attribute in turn at each place where a new function was created out of an old one, with the result that obscure attributes were regularly forgotten (like the collector or the section). Hopefully now everything is uniform and nothing is forgotten. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51567 91177308-0d34-0410-b5e6-96231b3b80d8
173 lines
6.2 KiB
C++
173 lines
6.2 KiB
C++
//===-- ExtractGV.cpp - Global Value 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 global values
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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/Constants.h"
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#include "llvm/Transforms/IPO.h"
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#include "llvm/Support/Compiler.h"
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#include <algorithm>
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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 GVExtractorPass : public ModulePass {
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std::vector<GlobalValue*> Named;
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bool deleteStuff;
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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 GVExtractorPass(std::vector<GlobalValue*>& GVs, bool deleteS = true,
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bool relinkCallees = false)
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: ModulePass((intptr_t)&ID), Named(GVs), deleteStuff(deleteS),
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reLink(relinkCallees) {}
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bool runOnModule(Module &M) {
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if (Named.size() == 0) {
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return false; // Nothing to extract
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}
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if (deleteStuff)
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return deleteGV();
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M.setModuleInlineAsm("");
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return isolateGV(M);
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}
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bool deleteGV() {
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for (std::vector<GlobalValue*>::iterator GI = Named.begin(),
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GE = Named.end(); GI != GE; ++GI) {
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if (Function* NamedFunc = dyn_cast<Function>(&*GI)) {
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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 = NamedFunc->begin(), BE = NamedFunc->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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NamedFunc->setLinkage(GlobalValue::ExternalLinkage);
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NamedFunc->deleteBody();
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assert(NamedFunc->isDeclaration() && "This didn't make the function external!");
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} else {
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if (!(*GI)->isDeclaration()) {
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cast<GlobalVariable>(*GI)->setInitializer(0); //clear the initializer
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(*GI)->setLinkage(GlobalValue::ExternalLinkage);
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}
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}
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}
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return true;
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}
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bool isolateGV(Module &M) {
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// Mark all globals 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->setLinkage(GlobalValue::InternalLinkage);
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}
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for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
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if (!I->isDeclaration()) {
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I->setLinkage(GlobalValue::InternalLinkage);
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}
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// Make sure our result is globally accessible...
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// by putting them in the used array
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{
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std::vector<Constant *> AUGs;
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const Type *SBP= PointerType::getUnqual(Type::Int8Ty);
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for (std::vector<GlobalValue*>::iterator GI = Named.begin(),
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GE = Named.end(); GI != GE; ++GI) {
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(*GI)->setLinkage(GlobalValue::ExternalLinkage);
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AUGs.push_back(ConstantExpr::getBitCast(*GI, SBP));
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}
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ArrayType *AT = ArrayType::get(SBP, AUGs.size());
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Constant *Init = ConstantArray::get(AT, AUGs);
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GlobalValue *gv = new GlobalVariable(AT, false,
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GlobalValue::AppendingLinkage,
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Init, "llvm.used", &M);
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gv->setSection("llvm.metadata");
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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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// globals. 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 (std::find(Named.begin(), Named.end(), &*I) == Named.end()) {
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Function *New = Function::Create(I->getFunctionType(),
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GlobalValue::ExternalLinkage);
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New->copyAttributesFrom(I);
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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 (std::find(Named.begin(), Named.end(), &*I) == Named.end()) {
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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 GVExtractorPass::ID = 0;
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}
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ModulePass *llvm::createGVExtractionPass(std::vector<GlobalValue*>& GVs,
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bool deleteFn, bool relinkCallees) {
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return new GVExtractorPass(GVs, deleteFn, relinkCallees);
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}
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