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7e70829632
For details, See: docs/2002-06-25-MegaPatchInfo.txt git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2779 91177308-0d34-0410-b5e6-96231b3b80d8
106 lines
3.6 KiB
C++
106 lines
3.6 KiB
C++
//===----------------------------------------------------------------------===//
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// LLVM extract Utility
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//
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// This utility changes the input module to only contain a single function,
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// which is primarily used for debugging transformations.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Module.h"
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#include "llvm/PassManager.h"
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#include "llvm/Bytecode/Reader.h"
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#include "llvm/Bytecode/WriteBytecodePass.h"
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#include "llvm/GlobalVariable.h"
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#include "llvm/Function.h"
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#include "llvm/Transforms/IPO/GlobalDCE.h"
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#include "llvm/Transforms/ConstantMerge.h"
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#include "llvm/Transforms/CleanupGCCOutput.h"
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#include "Support/CommandLine.h"
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#include <memory>
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static cl::String InputFilename("", "Specify input bytecode file", 0, "-");
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static cl::String ExtractFunc("func", "Specify function to extract", 0, "main");
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struct FunctionExtractorPass : public Pass {
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const char *getPassName() const { return "Function Extractor"; }
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bool run(Module &M) {
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// Mark all global variables to be internal
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for (Module::giterator I = M.gbegin(), E = M.gend(); I != E; ++I)
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I->setInternalLinkage(true);
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Function *Named = 0;
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// Loop over all of the functions in the module, dropping all references in
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// functions that are not the named function.
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for (Module::iterator I = M.begin(), E = M.end(); I != E;)
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// Check to see if this is the named function!
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if (!Named && I->getName() == ExtractFunc) {
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// Yes, it is. Keep track of it...
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Named = I;
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// Make sure it's globally accessable...
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Named->setInternalLinkage(false);
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// Remove the named function from the module.
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M.getFunctionList().remove(I);
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} else {
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// Nope it's not the named function, delete the body of the function
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I->dropAllReferences();
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++I;
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}
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// All of the functions that still have uses now must be used by global
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// variables or the named function. Loop through them and create a new,
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// external function for the used ones... making all uses point to the new
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// functions.
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std::vector<Function*> NewFunctions;
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for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
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if (!I->use_empty()) {
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Function *New = new Function(I->getFunctionType(), false, I->getName());
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I->replaceAllUsesWith(New);
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NewFunctions.push_back(New);
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}
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// Now the module only has unused functions with their references dropped.
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// Delete them all now!
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M.getFunctionList().clear();
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// Re-insert the named function...
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if (Named)
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M.getFunctionList().push_back(Named);
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else
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std::cerr << "Warning: Function '" << ExtractFunc << "' not found!\n";
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// Insert all of the function stubs...
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M.getFunctionList().insert(M.end(), NewFunctions.begin(),
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NewFunctions.end());
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return true;
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}
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};
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int main(int argc, char **argv) {
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cl::ParseCommandLineOptions(argc, argv, " llvm extractor\n");
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std::auto_ptr<Module> M(ParseBytecodeFile(InputFilename));
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if (M.get() == 0) {
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std::cerr << "bytecode didn't read correctly.\n";
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return 1;
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}
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// In addition to just parsing the input from GCC, we also want to spiff it up
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// a little bit. Do this now.
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//
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PassManager Passes;
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Passes.add(new FunctionExtractorPass());
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Passes.add(createGlobalDCEPass()); // Delete unreachable globals
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Passes.add(createConstantMergePass()); // Merge dup global constants
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Passes.add(createCleanupGCCOutputPass()); // Fix gccisms
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Passes.add(new WriteBytecodePass(&std::cout)); // Write bytecode to file...
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Passes.run(*M.get());
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return 0;
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}
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