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//===-- 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 "llvm/ADT/SetVector.h"
#include <algorithm>
using namespace llvm;
namespace {
/// @brief A pass to extract specific functions and their dependencies.
class GVExtractorPass : public ModulePass {
SetVector<GlobalValue *> Named;
bool deleteStuff;
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)
: ModulePass(ID), Named(GVs.begin(), GVs.end()), deleteStuff(deleteS) {}
bool runOnModule(Module &M) {
// Visit the global inline asm.
if (!deleteStuff)
M.setModuleInlineAsm("");
// For simplicity, just give all GlobalValues ExternalLinkage. A trickier
// implementation could figure out which GlobalValues are actually
// referenced by the Named set, and which GlobalValues in the rest of
// the module are referenced by the NamedSet, and get away with leaving
// more internal and private things internal and private. But for now,
// be conservative and simple.
// Visit the GlobalVariables.
for (Module::global_iterator I = M.global_begin(), E = M.global_end();
I != E; ++I) {
if (deleteStuff == (bool)Named.count(I) && !I->isDeclaration()) {
I->setInitializer(0);
} else {
if (I->hasAvailableExternallyLinkage())
continue;
if (I->getName() == "llvm.global_ctors")
continue;
// @LOCALMOD-BEGIN - this is likely upstreamable
// Note: there will likely be more cases once this
// is exercises more thorougly.
if (I->getName() == "llvm.global_dtors")
continue;
// not observed yet
if (I->hasExternalWeakLinkage())
continue;
// @LOCALMOD-END
}
if (I->hasLocalLinkage())
I->setVisibility(GlobalValue::HiddenVisibility);
I->setLinkage(GlobalValue::ExternalLinkage);
}
// Visit the Functions.
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
if (deleteStuff == (bool)Named.count(I) && !I->isDeclaration()) {
I->deleteBody();
} else {
if (I->hasAvailableExternallyLinkage())
continue;
// @LOCALMOD-BEGIN - this is likely upstreamable
// Note: there will likely be more cases once this
// is exercises more thorougly.
// observed for pthread_cancel
if (I->hasExternalWeakLinkage())
continue;
// @LOCALMOD-END
}
if (I->hasLocalLinkage())
I->setVisibility(GlobalValue::HiddenVisibility);
I->setLinkage(GlobalValue::ExternalLinkage);
}
return true;
}
};
char GVExtractorPass::ID = 0;
}
ModulePass *llvm::createGVExtractionPass(std::vector<GlobalValue*>& GVs,
bool deleteFn) {
return new GVExtractorPass(GVs, deleteFn);
}
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