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>
22 using namespace llvm;
23
24 namespace {
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 ///
GVExtractorPass(std::vector<GlobalValue * > & GVs,bool deleteS=true)36 explicit GVExtractorPass(std::vector<GlobalValue*>& GVs, bool deleteS = true)
37 : ModulePass(ID), Named(GVs.begin(), GVs.end()), deleteStuff(deleteS) {}
38
runOnModule(Module & M)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
createGVExtractionPass(std::vector<GlobalValue * > & GVs,bool deleteFn)89 ModulePass *llvm::createGVExtractionPass(std::vector<GlobalValue*>& GVs,
90 bool deleteFn) {
91 return new GVExtractorPass(GVs, deleteFn);
92 }
93