Initial checkin of the "extract" utility
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2716 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/llvm-extract/llvm-extract.cpp b/tools/llvm-extract/llvm-extract.cpp
new file mode 100644
index 0000000..7a6a1c1
--- /dev/null
+++ b/tools/llvm-extract/llvm-extract.cpp
@@ -0,0 +1,104 @@
+//===----------------------------------------------------------------------===//
+// LLVM extract Utility
+//
+// This utility changes the input module to only contain a single function,
+// which is primarily used for debugging transformations.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Module.h"
+#include "llvm/PassManager.h"
+#include "llvm/Bytecode/Reader.h"
+#include "llvm/Bytecode/WriteBytecodePass.h"
+#include "llvm/GlobalVariable.h"
+#include "llvm/Function.h"
+#include "llvm/Transforms/IPO/GlobalDCE.h"
+#include "llvm/Transforms/ConstantMerge.h"
+#include "llvm/Transforms/CleanupGCCOutput.h"
+#include "Support/CommandLine.h"
+#include <memory>
+
+static cl::String InputFilename("", "Specify input bytecode file", 0, "-");
+static cl::String ExtractFunc("func", "Specify function to extract", 0, "main");
+
+struct FunctionExtractorPass : public Pass {
+ const char *getPassName() const { return "Function Extractor"; }
+
+ bool run(Module *M) {
+ // Mark all global variables to be internal
+ for (Module::giterator I = M->gbegin(), E = M->gend(); I != E; ++I)
+ (*I)->setInternalLinkage(true);
+
+ Function *Named = 0;
+
+ // Loop over all of the functions in the module, dropping all references in
+ // functions that are not the named function.
+ for (Module::iterator I = M->begin(), E = M->end(); I != E;)
+ // Check to see if this is the named function!
+ if (!Named && (*I)->getName() == ExtractFunc) {
+ // Yes, it is. Keep track of it...
+ Named = *I;
+
+ // Remove the named function from the module.
+ M->getFunctionList().remove(I);
+ E = M->end();
+ } else {
+ // Nope it's not the named function, delete the body of the function
+ (*I)->dropAllReferences();
+ ++I;
+ }
+
+ // All of the functions that still have uses now must be used by global
+ // variables or the named function. Loop through them and create a new,
+ // external function for the used ones... making all uses point to the new
+ // functions.
+ std::vector<Function*> NewFunctions;
+
+ for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
+ if (!(*I)->use_empty()) {
+ Function *New = new Function((*I)->getFunctionType(), false,
+ (*I)->getName());
+ (*I)->replaceAllUsesWith(New);
+ NewFunctions.push_back(New);
+ }
+
+ // Now the module only has unused functions with their references dropped.
+ // Delete them all now!
+ M->getFunctionList().delete_all();
+
+ // Re-insert the named function...
+ if (Named)
+ M->getFunctionList().push_back(Named);
+ else
+ std::cerr << "Warning: Function '" << ExtractFunc << "' not found!\n";
+
+ // Insert all of the function stubs...
+ M->getFunctionList().insert(M->end(), NewFunctions.begin(),
+ NewFunctions.end());
+ return true;
+ }
+};
+
+
+int main(int argc, char **argv) {
+ cl::ParseCommandLineOptions(argc, argv, " llvm extractor\n");
+
+ std::auto_ptr<Module> M(ParseBytecodeFile(InputFilename));
+ if (M.get() == 0) {
+ std::cerr << "bytecode didn't read correctly.\n";
+ return 1;
+ }
+
+ // In addition to just parsing the input from GCC, we also want to spiff it up
+ // a little bit. Do this now.
+ //
+ PassManager Passes;
+ Passes.add(new FunctionExtractorPass());
+ Passes.add(createGlobalDCEPass()); // Delete unreachable globals
+ Passes.add(createConstantMergePass()); // Merge dup global constants
+ Passes.add(createCleanupGCCOutputPass()); // Fix gccisms
+ Passes.add(new WriteBytecodePass(&std::cout)); // Write bytecode to file...
+
+ Passes.run(M.get());
+ return 0;
+}