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98 lines
2.9 KiB
C++
98 lines
2.9 KiB
C++
//===-- StripExternals.cpp - Strip available_externally symbols -----------===//
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//
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// LDC – the LLVM D compiler
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//
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// This file is distributed under the BSD-style LDC license. See the LICENSE
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// file for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This transform stips the bodies of available_externally functions and
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// initializers of available_externally globals, turning them into external
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// declarations.
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// This is useful to allow Global DCE (-globaldce) to clean up references to
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// globals only used by available_externally functions and initializers.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "strip-externals"
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#include "Passes.h"
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#if LDC_LLVM_VER >= 303
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#include "llvm/IR/Module.h"
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#else
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#include "llvm/Module.h"
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#endif
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#include "llvm/Pass.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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STATISTIC(NumFunctions, "Number of function bodies removed");
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STATISTIC(NumVariables, "Number of global initializers removed");
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namespace {
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struct LLVM_LIBRARY_VISIBILITY StripExternals : public ModulePass {
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static char ID; // Pass identification, replacement for typeid
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StripExternals() : ModulePass(ID) {}
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// run - Do the StripExternals pass on the specified module.
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//
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bool runOnModule(Module &M);
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};
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}
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char StripExternals::ID = 0;
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static RegisterPass<StripExternals>
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X("strip-externals", "Strip available_externally bodies and initializers");
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ModulePass *createStripExternalsPass() { return new StripExternals(); }
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bool StripExternals::runOnModule(Module &M) {
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bool Changed = false;
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for (Module::iterator I = M.begin(); I != M.end(); ) {
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if (I->hasAvailableExternallyLinkage()) {
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assert(!I->isDeclaration()&&"Declarations can't be available_externally");
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Changed = true;
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++NumFunctions;
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if (I->use_empty()) {
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DEBUG(errs() << "Deleting function: " << *I);
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Module::iterator todelete = I;
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++I;
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todelete->eraseFromParent();
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continue;
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} else {
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I->deleteBody();
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DEBUG(errs() << "Deleted function body: " << *I);
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}
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}
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++I;
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}
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for (Module::global_iterator I = M.global_begin();
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I != M.global_end(); ) {
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if (I->hasAvailableExternallyLinkage()) {
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assert(!I->isDeclaration()&&"Declarations can't be available_externally");
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Changed = true;
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++NumVariables;
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if (I->use_empty()) {
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DEBUG(errs() << "Deleting global: " << *I);
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Module::global_iterator todelete = I;
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++I;
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todelete->eraseFromParent();
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continue;
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} else {
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I->setInitializer(0);
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I->setLinkage(GlobalValue::ExternalLinkage);
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DEBUG(errs() << "Deleted initializer: " << *I);
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}
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}
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++I;
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}
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return Changed;
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}
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