ExtractGV.cpp revision 223017
1//===-- ExtractGV.cpp - Global Value extraction pass ----------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This pass extracts global values 11// 12//===----------------------------------------------------------------------===// 13 14#include "llvm/Instructions.h" 15#include "llvm/LLVMContext.h" 16#include "llvm/Module.h" 17#include "llvm/Pass.h" 18#include "llvm/Constants.h" 19#include "llvm/Transforms/IPO.h" 20#include "llvm/ADT/SetVector.h" 21#include <algorithm> 22using namespace llvm; 23 24namespace { 25 /// @brief A pass to extract specific functions and their dependencies. 26 class GVExtractorPass : public ModulePass { 27 SetVector<GlobalValue *> Named; 28 bool deleteStuff; 29 public: 30 static char ID; // Pass identification, replacement for typeid 31 32 /// FunctionExtractorPass - If deleteFn is true, this pass deletes as the 33 /// specified function. Otherwise, it deletes as much of the module as 34 /// possible, except for the function specified. 35 /// 36 explicit GVExtractorPass(std::vector<GlobalValue*>& GVs, bool deleteS = true) 37 : ModulePass(ID), Named(GVs.begin(), GVs.end()), deleteStuff(deleteS) {} 38 39 bool runOnModule(Module &M) { 40 // Visit the global inline asm. 41 if (!deleteStuff) 42 M.setModuleInlineAsm(""); 43 44 // For simplicity, just give all GlobalValues ExternalLinkage. A trickier 45 // implementation could figure out which GlobalValues are actually 46 // referenced by the Named set, and which GlobalValues in the rest of 47 // the module are referenced by the NamedSet, and get away with leaving 48 // more internal and private things internal and private. But for now, 49 // be conservative and simple. 50 51 // Visit the GlobalVariables. 52 for (Module::global_iterator I = M.global_begin(), E = M.global_end(); 53 I != E; ++I) { 54 if (deleteStuff == (bool)Named.count(I) && !I->isDeclaration()) { 55 I->setInitializer(0); 56 } else { 57 if (I->hasAvailableExternallyLinkage()) 58 continue; 59 if (I->getName() == "llvm.global_ctors") 60 continue; 61 } 62 63 if (I->hasLocalLinkage()) 64 I->setVisibility(GlobalValue::HiddenVisibility); 65 I->setLinkage(GlobalValue::ExternalLinkage); 66 } 67 68 // Visit the Functions. 69 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) { 70 if (deleteStuff == (bool)Named.count(I) && !I->isDeclaration()) { 71 I->deleteBody(); 72 } else { 73 if (I->hasAvailableExternallyLinkage()) 74 continue; 75 } 76 77 if (I->hasLocalLinkage()) 78 I->setVisibility(GlobalValue::HiddenVisibility); 79 I->setLinkage(GlobalValue::ExternalLinkage); 80 } 81 82 return true; 83 } 84 }; 85 86 char GVExtractorPass::ID = 0; 87} 88 89ModulePass *llvm::createGVExtractionPass(std::vector<GlobalValue*>& GVs, 90 bool deleteFn) { 91 return new GVExtractorPass(GVs, deleteFn); 92} 93