//===-- Writer.cpp - Library for writing VM bytecode files -------*- C++ -*--=// // // This library implements the functionality defined in llvm/Bytecode/Writer.h // // This library uses the Analysis library to figure out offsets for // variables in the method tables... // // Note that this file uses an unusual technique of outputting all the bytecode // to a deque of unsigned char's, then copies the deque to an ostream. The // reason for this is that we must do "seeking" in the stream to do back- // patching, and some very important ostreams that we want to support (like // pipes) do not support seeking. :( :( :( // // The choice of the deque data structure is influenced by the extremely fast // "append" speed, plus the free "seek"/replace in the middle of the stream. I // didn't use a vector because the stream could end up very large and copying // the whole thing to reallocate would be kinda silly. // // Note that the performance of this library is not terribly important, because // it shouldn't be used by JIT type applications... so it is not a huge focus // at least. :) // //===----------------------------------------------------------------------===// #include "WriterInternals.h" #include "llvm/Module.h" #include "llvm/GlobalVariable.h" #include "llvm/Method.h" #include "llvm/BasicBlock.h" #include "llvm/ConstPoolVals.h" #include "llvm/SymbolTable.h" #include "llvm/DerivedTypes.h" #include "llvm/Support/STLExtras.h" #include #include BytecodeWriter::BytecodeWriter(deque &o, const Module *M) : Out(o), Table(M, false) { outputSignature(); // Emit the top level CLASS block. BytecodeBlock ModuleBlock(BytecodeFormat::Module, Out); // Output the ID of first "derived" type: output_vbr((unsigned)Type::FirstDerivedTyID, Out); align32(Out); // Output module level constants, including types used by the method protos outputConstants(false); // The ModuleInfoBlock follows directly after the Module constant pool outputModuleInfoBlock(M); // Do the whole module now! Process each method at a time... for_each(M->begin(), M->end(), bind_obj(this, &BytecodeWriter::processMethod)); // If needed, output the symbol table for the module... if (M->hasSymbolTable()) outputSymbolTable(*M->getSymbolTable()); } // TODO: REMOVE #include "llvm/Assembly/Writer.h" void BytecodeWriter::outputConstants(bool isMethod) { BytecodeBlock CPool(BytecodeFormat::ConstantPool, Out); unsigned NumPlanes = Table.getNumPlanes(); for (unsigned pno = 0; pno < NumPlanes; pno++) { const vector &Plane = Table.getPlane(pno); if (Plane.empty()) continue; // Skip empty type planes... unsigned ValNo = 0; if (isMethod) // Don't reemit module constants ValNo = Table.getModuleLevel(pno); else if (pno == Type::TypeTyID) ValNo = Type::FirstDerivedTyID; // Start emitting at the derived types... // Scan through and ignore method arguments... for (; ValNo < Plane.size() && isa(Plane[ValNo]); ValNo++) /*empty*/; unsigned NC = ValNo; // Number of constants for (; NC < Plane.size() && (isa(Plane[NC]) || isa(Plane[NC])); NC++) /*empty*/; NC -= ValNo; // Convert from index into count if (NC == 0) continue; // Skip empty type planes... // Output type header: [num entries][type id number] // output_vbr(NC, Out); // Output the Type ID Number... int Slot = Table.getValSlot(Plane.front()->getType()); assert (Slot != -1 && "Type in constant pool but not in method!!"); output_vbr((unsigned)Slot, Out); //cout << "Emitting " << NC << " constants of type '" // << Plane.front()->getType()->getName() << "' = Slot #" << Slot << endl; for (unsigned i = ValNo; i < ValNo+NC; ++i) { const Value *V = Plane[i]; if (const ConstPoolVal *CPV = dyn_cast(V)) { //cerr << "Serializing value: <" << V->getType() << ">: " // << ((const ConstPoolVal*)V)->getStrValue() << ":" // << Out.size() << "\n"; outputConstant(CPV); } else { const Type *Ty = cast(V); outputType(Ty); } } } } void BytecodeWriter::outputModuleInfoBlock(const Module *M) { BytecodeBlock ModuleInfoBlock(BytecodeFormat::ModuleGlobalInfo, Out); // Output the types for the global variables in the module... for (Module::const_giterator I = M->gbegin(), End = M->gend(); I != End;++I) { const GlobalVariable *GV = *I; int Slot = Table.getValSlot(GV->getType()); assert(Slot != -1 && "Module global vars is broken!"); // Fields: bit0 = isConstant, bit1 = hasInitializer, bit2+ = slot# unsigned oSlot = ((unsigned)Slot << 2) | (GV->hasInitializer() << 1) | isa(GV); output_vbr(oSlot, Out); // If we have an initialized, output it now. if (GV->hasInitializer()) { Slot = Table.getValSlot(GV->getInitializer()); assert(Slot != -1 && "No slot for global var initializer!"); output_vbr((unsigned)Slot, Out); } } output_vbr((unsigned)Table.getValSlot(Type::VoidTy), Out); // Output the types of the methods in this module... for (Module::const_iterator I = M->begin(), End = M->end(); I != End; ++I) { int Slot = Table.getValSlot((*I)->getType()); assert(Slot != -1 && "Module const pool is broken!"); assert(Slot >= Type::FirstDerivedTyID && "Derived type not in range!"); output_vbr((unsigned)Slot, Out); } output_vbr((unsigned)Table.getValSlot(Type::VoidTy), Out); align32(Out); } void BytecodeWriter::processMethod(const Method *M) { BytecodeBlock MethodBlock(BytecodeFormat::Method, Out); // Only output the constant pool and other goodies if needed... if (!M->isExternal()) { // Get slot information about the method... Table.incorporateMethod(M); // Output information about the constants in the method... outputConstants(true); // Output basic block nodes... for_each(M->begin(), M->end(), bind_obj(this, &BytecodeWriter::processBasicBlock)); // If needed, output the symbol table for the method... if (M->hasSymbolTable()) outputSymbolTable(*M->getSymbolTable()); Table.purgeMethod(); } } void BytecodeWriter::processBasicBlock(const BasicBlock *BB) { BytecodeBlock MethodBlock(BytecodeFormat::BasicBlock, Out); // Process all the instructions in the bb... for_each(BB->begin(), BB->end(), bind_obj(this, &BytecodeWriter::processInstruction)); } void BytecodeWriter::outputSymbolTable(const SymbolTable &MST) { BytecodeBlock MethodBlock(BytecodeFormat::SymbolTable, Out); for (SymbolTable::const_iterator TI = MST.begin(); TI != MST.end(); ++TI) { SymbolTable::type_const_iterator I = MST.type_begin(TI->first); SymbolTable::type_const_iterator End = MST.type_end(TI->first); int Slot; if (I == End) continue; // Don't mess with an absent type... // Symtab block header: [num entries][type id number] output_vbr(MST.type_size(TI->first), Out); Slot = Table.getValSlot(TI->first); assert(Slot != -1 && "Type in symtab, but not in table!"); output_vbr((unsigned)Slot, Out); for (; I != End; ++I) { // Symtab entry: [def slot #][name] Slot = Table.getValSlot(I->second); assert(Slot != -1 && "Value in symtab but has no slot number!!"); output_vbr((unsigned)Slot, Out); output(I->first, Out, false); // Don't force alignment... } } } void WriteBytecodeToFile(const Module *C, ostream &Out) { assert(C && "You can't write a null module!!"); deque Buffer; // This object populates buffer for us... BytecodeWriter BCW(Buffer, C); // Okay, write the deque out to the ostream now... the deque is not // sequential in memory, however, so write out as much as possible in big // chunks, until we're done. // deque::const_iterator I = Buffer.begin(), E = Buffer.end(); while (I != E) { // Loop until it's all written // Scan to see how big this chunk is... const unsigned char *ChunkPtr = &*I; const unsigned char *LastPtr = ChunkPtr; while (I != E) { const unsigned char *ThisPtr = &*++I; if (LastPtr+1 != ThisPtr) break;// Advanced by more than a byte of memory? LastPtr = ThisPtr; } // Write out the chunk... Out.write(ChunkPtr, LastPtr-ChunkPtr+(I != E)); } Out.flush(); }