1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
|
//===-- ExtractGV.cpp - Global Value extraction pass ----------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass extracts global values
//
//===----------------------------------------------------------------------===//
#include "llvm/Instructions.h"
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Constants.h"
#include "llvm/Transforms/IPO.h"
#include <algorithm>
using namespace llvm;
namespace {
/// @brief A pass to extract specific functions and their dependencies.
class GVExtractorPass : public ModulePass {
std::vector<GlobalValue*> Named;
bool deleteStuff;
bool reLink;
public:
static char ID; // Pass identification, replacement for typeid
/// FunctionExtractorPass - If deleteFn is true, this pass deletes as the
/// specified function. Otherwise, it deletes as much of the module as
/// possible, except for the function specified.
///
explicit GVExtractorPass(std::vector<GlobalValue*>& GVs, bool deleteS = true,
bool relinkCallees = false)
: ModulePass(&ID), Named(GVs), deleteStuff(deleteS),
reLink(relinkCallees) {}
bool runOnModule(Module &M) {
if (Named.size() == 0) {
return false; // Nothing to extract
}
if (deleteStuff)
return deleteGV();
M.setModuleInlineAsm("");
return isolateGV(M);
}
bool deleteGV() {
for (std::vector<GlobalValue*>::iterator GI = Named.begin(),
GE = Named.end(); GI != GE; ++GI) {
if (Function* NamedFunc = dyn_cast<Function>(*GI)) {
// If we're in relinking mode, set linkage of all internal callees to
// external. This will allow us extract function, and then - link
// everything together
if (reLink) {
for (Function::iterator B = NamedFunc->begin(), BE = NamedFunc->end();
B != BE; ++B) {
for (BasicBlock::iterator I = B->begin(), E = B->end();
I != E; ++I) {
if (CallInst* callInst = dyn_cast<CallInst>(&*I)) {
Function* Callee = callInst->getCalledFunction();
if (Callee && Callee->hasLocalLinkage())
Callee->setLinkage(GlobalValue::ExternalLinkage);
}
}
}
}
NamedFunc->setLinkage(GlobalValue::ExternalLinkage);
NamedFunc->deleteBody();
assert(NamedFunc->isDeclaration() && "This didn't make the function external!");
} else {
if (!(*GI)->isDeclaration()) {
cast<GlobalVariable>(*GI)->setInitializer(0); //clear the initializer
(*GI)->setLinkage(GlobalValue::ExternalLinkage);
}
}
}
return true;
}
bool isolateGV(Module &M) {
// Mark all globals internal
// FIXME: what should we do with private linkage?
for (Module::global_iterator I = M.global_begin(), E = M.global_end(); I != E; ++I)
if (!I->isDeclaration()) {
I->setLinkage(GlobalValue::InternalLinkage);
}
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
if (!I->isDeclaration()) {
I->setLinkage(GlobalValue::InternalLinkage);
}
// Make sure our result is globally accessible...
// by putting them in the used array
{
std::vector<Constant *> AUGs;
const Type *SBP=
Type::getInt8PtrTy(M.getContext());
for (std::vector<GlobalValue*>::iterator GI = Named.begin(),
GE = Named.end(); GI != GE; ++GI) {
(*GI)->setLinkage(GlobalValue::ExternalLinkage);
AUGs.push_back(ConstantExpr::getBitCast(*GI, SBP));
}
ArrayType *AT = ArrayType::get(SBP, AUGs.size());
Constant *Init = ConstantArray::get(AT, AUGs);
GlobalValue *gv = new GlobalVariable(M, AT, false,
GlobalValue::AppendingLinkage,
Init, "llvm.used");
gv->setSection("llvm.metadata");
}
// All of the functions may be used by global variables or the named
// globals. Loop through them and create a new, external functions that
// can be "used", instead of ones with bodies.
std::vector<Function*> NewFunctions;
Function *Last = --M.end(); // Figure out where the last real fn is.
for (Module::iterator I = M.begin(); ; ++I) {
if (std::find(Named.begin(), Named.end(), &*I) == Named.end()) {
Function *New = Function::Create(I->getFunctionType(),
GlobalValue::ExternalLinkage);
New->copyAttributesFrom(I);
// If it's not the named function, delete the body of the function
I->dropAllReferences();
M.getFunctionList().push_back(New);
NewFunctions.push_back(New);
New->takeName(I);
}
if (&*I == Last) break; // Stop after processing the last function
}
// Now that we have replacements all set up, loop through the module,
// deleting the old functions, replacing them with the newly created
// functions.
if (!NewFunctions.empty()) {
unsigned FuncNum = 0;
Module::iterator I = M.begin();
do {
if (std::find(Named.begin(), Named.end(), &*I) == Named.end()) {
// Make everything that uses the old function use the new dummy fn
I->replaceAllUsesWith(NewFunctions[FuncNum++]);
Function *Old = I;
++I; // Move the iterator to the new function
// Delete the old function!
M.getFunctionList().erase(Old);
} else {
++I; // Skip the function we are extracting
}
} while (&*I != NewFunctions[0]);
}
return true;
}
};
char GVExtractorPass::ID = 0;
}
ModulePass *llvm::createGVExtractionPass(std::vector<GlobalValue*>& GVs,
bool deleteFn, bool relinkCallees) {
return new GVExtractorPass(GVs, deleteFn, relinkCallees);
}
|
