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
|
//===-- ExtractFunction.cpp - Function extraction pass --------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass extracts
//
//===----------------------------------------------------------------------===//
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Support/Compiler.h"
using namespace llvm;
namespace {
/// @brief A pass to extract specific functions and their dependencies.
class VISIBILITY_HIDDEN FunctionExtractorPass : public ModulePass {
Function *Named;
bool deleteFunc;
bool reLink;
public:
static const int ID; // Pass identifcation, 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.
///
FunctionExtractorPass(Function *F = 0, bool deleteFn = true,
bool relinkCallees = false)
: ModulePass((intptr_t)&ID), Named(F), deleteFunc(deleteFn),
reLink(relinkCallees) {}
bool runOnModule(Module &M) {
if (Named == 0) {
Named = M.getFunction("main");
if (Named == 0) return false; // No function to extract
}
if (deleteFunc)
return deleteFunction();
M.setModuleInlineAsm("");
return isolateFunction(M);
}
bool deleteFunction() {
// 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 = Named->begin(), BE = Named->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->hasInternalLinkage())
Callee->setLinkage(GlobalValue::ExternalLinkage);
}
}
}
}
Named->setLinkage(GlobalValue::ExternalLinkage);
Named->deleteBody();
assert(Named->isDeclaration() && "This didn't make the function external!");
return true;
}
bool isolateFunction(Module &M) {
// Make sure our result is globally accessible...
Named->setLinkage(GlobalValue::ExternalLinkage);
// Mark all global variables internal
for (Module::global_iterator I = M.global_begin(), E = M.global_end(); I != E; ++I)
if (!I->isDeclaration()) {
I->setInitializer(0); // Make all variables external
I->setLinkage(GlobalValue::ExternalLinkage);
}
// All of the functions may be used by global variables or the named
// function. 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 (&*I != Named) {
Function *New = new Function(I->getFunctionType(),
GlobalValue::ExternalLinkage);
New->setCallingConv(I->getCallingConv());
// 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 (&*I != Named) {
// 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;
}
};
const int FunctionExtractorPass::ID = 0;
RegisterPass<FunctionExtractorPass> X("extract", "Function Extractor");
}
ModulePass *llvm::createFunctionExtractionPass(Function *F, bool deleteFn,
bool relinkCallees) {
return new FunctionExtractorPass(F, deleteFn, relinkCallees);
}
|
