forked from OSchip/llvm-project
86 lines
2.7 KiB
C++
86 lines
2.7 KiB
C++
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#include "llvm/Transforms/IPO.h"
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#include "llvm/Pass.h"
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#include "llvm/Module.h"
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namespace {
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class FunctionExtractorPass : public Pass {
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Function *Named;
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public:
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FunctionExtractorPass(Function *F = 0) : Named(F) {}
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bool run(Module &M) {
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if (Named == 0) {
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Named = M.getMainFunction();
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if (Named == 0) return false; // No function to extract
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}
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// Make sure our result is globally accessible...
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Named->setLinkage(GlobalValue::ExternalLinkage);
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// Mark all global variables internal
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for (Module::giterator I = M.gbegin(), E = M.gend(); I != E; ++I)
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if (!I->isExternal()) {
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I->setInitializer(0); // Make all variables external
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I->setLinkage(GlobalValue::ExternalLinkage);
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}
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// All of the functions may be used by global variables or the named
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// function. Loop through them and create a new, external functions that
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// can be "used", instead of ones with bodies.
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//
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std::vector<Function*> NewFunctions;
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Function *Last = &M.back(); // Figure out where the last real fn is...
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for (Module::iterator I = M.begin(); ; ++I) {
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if (&*I != Named) {
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Function *New = new Function(I->getFunctionType(),
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GlobalValue::ExternalLinkage,
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I->getName());
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I->setName(""); // Remove Old name
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// If it's not the named function, delete the body of the function
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I->dropAllReferences();
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M.getFunctionList().push_back(New);
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NewFunctions.push_back(New);
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}
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if (&*I == Last) break; // Stop after processing the last function
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}
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// Now that we have replacements all set up, loop through the module,
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// deleting the old functions, replacing them with the newly created
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// functions.
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if (!NewFunctions.empty()) {
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unsigned FuncNum = 0;
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Module::iterator I = M.begin();
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do {
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if (&*I != Named) {
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// Make everything that uses the old function use the new dummy fn
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I->replaceAllUsesWith(NewFunctions[FuncNum++]);
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Function *Old = I;
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++I; // Move the iterator to the new function
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// Delete the old function!
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M.getFunctionList().erase(Old);
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} else {
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++I; // Skip the function we are extracting
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}
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} while (&*I != NewFunctions[0]);
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}
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return true;
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}
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};
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RegisterPass<FunctionExtractorPass> X("extract", "Function Extractor");
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}
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Pass *createFunctionExtractionPass(Function *F) {
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return new FunctionExtractorPass(F);
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}
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