| //===-- Writer.cpp - Library for writing VM bytecode files ----------------===// |
| // |
| // This library implements the functionality defined in llvm/Bytecode/Writer.h |
| // |
| // Note that this file uses an unusual technique of outputting all the bytecode |
| // to a deque of unsigned char, 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/Bytecode/WriteBytecodePass.h" |
| #include "llvm/Module.h" |
| #include "llvm/SymbolTable.h" |
| #include "llvm/DerivedTypes.h" |
| #include "Support/STLExtras.h" |
| #include "Support/Statistic.h" |
| #include "Config/string.h" |
| #include <algorithm> |
| |
| static RegisterPass<WriteBytecodePass> X("emitbytecode", "Bytecode Writer"); |
| |
| static Statistic<> |
| BytesWritten("bytecodewriter", "Number of bytecode bytes written"); |
| |
| |
| BytecodeWriter::BytecodeWriter(std::deque<unsigned char> &o, const Module *M) |
| : Out(o), Table(M, false) { |
| |
| outputSignature(); |
| |
| // Emit the top level CLASS block. |
| BytecodeBlock ModuleBlock(BytecodeFormat::Module, Out); |
| |
| bool isBigEndian = M->getEndianness() == Module::BigEndian; |
| bool hasLongPointers = M->getPointerSize() == Module::Pointer64; |
| bool hasNoEndianness = M->getEndianness() == Module::AnyEndianness; |
| bool hasNoPointerSize = M->getPointerSize() == Module::AnyPointerSize; |
| |
| // Output the version identifier... we are currently on bytecode version #2 |
| unsigned Version = (2 << 4) | isBigEndian | (hasLongPointers << 1) | |
| (hasNoEndianness << 2) | (hasNoPointerSize << 3); |
| output_vbr(Version, Out); |
| align32(Out); |
| |
| { |
| BytecodeBlock CPool(BytecodeFormat::GlobalTypePlane, Out); |
| |
| // Write the type plane for types first because earlier planes (e.g. for a |
| // primitive type like float) may have constants constructed using types |
| // coming later (e.g., via getelementptr from a pointer type). The type |
| // plane is needed before types can be fwd or bkwd referenced. |
| const std::vector<const Value*> &Plane = Table.getPlane(Type::TypeTyID); |
| assert(!Plane.empty() && "No types at all?"); |
| unsigned ValNo = Type::FirstDerivedTyID; // Start at the derived types... |
| outputConstantsInPlane(Plane, ValNo); // Write out the types |
| } |
| |
| // The ModuleInfoBlock follows directly after the type information |
| outputModuleInfoBlock(M); |
| |
| // Output module level constants, used for global variable initializers |
| outputConstants(false); |
| |
| // Do the whole module now! Process each function at a time... |
| for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I) |
| outputFunction(I); |
| |
| // If needed, output the symbol table for the module... |
| outputSymbolTable(M->getSymbolTable()); |
| } |
| |
| // Helper function for outputConstants(). |
| // Writes out all the constants in the plane Plane starting at entry StartNo. |
| // |
| void BytecodeWriter::outputConstantsInPlane(const std::vector<const Value*> |
| &Plane, unsigned StartNo) { |
| unsigned ValNo = StartNo; |
| |
| // Scan through and ignore function arguments/global values... |
| for (; ValNo < Plane.size() && (isa<Argument>(Plane[ValNo]) || |
| isa<GlobalValue>(Plane[ValNo])); ValNo++) |
| /*empty*/; |
| |
| unsigned NC = ValNo; // Number of constants |
| for (; NC < Plane.size() && |
| (isa<Constant>(Plane[NC]) || isa<Type>(Plane[NC])); NC++) |
| /*empty*/; |
| NC -= ValNo; // Convert from index into count |
| if (NC == 0) return; // 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 function!!"); |
| output_vbr((unsigned)Slot, Out); |
| |
| //cerr << "Emitting " << NC << " constants of type '" |
| // << Plane.front()->getType()->getName() << "' = Slot #" << Slot << "\n"; |
| |
| for (unsigned i = ValNo; i < ValNo+NC; ++i) { |
| const Value *V = Plane[i]; |
| if (const Constant *CPV = dyn_cast<Constant>(V)) { |
| //cerr << "Serializing value: <" << V->getType() << ">: " << V << ":" |
| // << Out.size() << "\n"; |
| outputConstant(CPV); |
| } else { |
| outputType(cast<Type>(V)); |
| } |
| } |
| } |
| |
| void BytecodeWriter::outputConstants(bool isFunction) { |
| BytecodeBlock CPool(BytecodeFormat::ConstantPool, Out); |
| |
| unsigned NumPlanes = Table.getNumPlanes(); |
| |
| // Output the type plane before any constants! |
| if (isFunction && NumPlanes > Type::TypeTyID) { |
| const std::vector<const Value*> &Plane = Table.getPlane(Type::TypeTyID); |
| if (!Plane.empty()) { // Skip empty type planes... |
| unsigned ValNo = Table.getModuleLevel(Type::TypeTyID); |
| outputConstantsInPlane(Plane, ValNo); |
| } |
| } |
| |
| for (unsigned pno = 0; pno != NumPlanes; pno++) |
| if (pno != Type::TypeTyID) { // Type plane handled above. |
| const std::vector<const Value*> &Plane = Table.getPlane(pno); |
| if (!Plane.empty()) { // Skip empty type planes... |
| unsigned ValNo = 0; |
| if (isFunction) // Don't re-emit module constants |
| ValNo += Table.getModuleLevel(pno); |
| |
| if (pno >= Type::FirstDerivedTyID) { |
| // Skip zero initializer |
| if (ValNo == 0) |
| ValNo = 1; |
| } |
| |
| // Write out constants in the plane |
| outputConstantsInPlane(Plane, ValNo); |
| } |
| } |
| } |
| |
| 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) { |
| int Slot = Table.getValSlot(I->getType()); |
| assert(Slot != -1 && "Module global vars is broken!"); |
| |
| // Fields: bit0 = isConstant, bit1 = hasInitializer, bit2,3=Linkage, |
| // bit4+ = Slot # for type |
| unsigned oSlot = ((unsigned)Slot << 4) | ((unsigned)I->getLinkage() << 2) | |
| (I->hasInitializer() << 1) | I->isConstant(); |
| output_vbr(oSlot, Out); |
| |
| // If we have an initializer, output it now. |
| if (I->hasInitializer()) { |
| Slot = Table.getValSlot((Value*)I->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 functions 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::outputFunction(const Function *F) { |
| BytecodeBlock FunctionBlock(BytecodeFormat::Function, Out); |
| output_vbr((unsigned)F->getLinkage(), Out); |
| // Only output the constant pool and other goodies if needed... |
| if (!F->isExternal()) { |
| |
| // Get slot information about the function... |
| Table.incorporateFunction(F); |
| |
| // Output information about the constants in the function... |
| outputConstants(true); |
| |
| // Output basic block nodes... |
| for (Function::const_iterator I = F->begin(), E = F->end(); I != E; ++I) |
| processBasicBlock(*I); |
| |
| // If needed, output the symbol table for the function... |
| outputSymbolTable(F->getSymbolTable()); |
| |
| Table.purgeFunction(); |
| } |
| } |
| |
| |
| void BytecodeWriter::processBasicBlock(const BasicBlock &BB) { |
| BytecodeBlock FunctionBlock(BytecodeFormat::BasicBlock, Out); |
| // Process all the instructions in the bb... |
| for(BasicBlock::const_iterator I = BB.begin(), E = BB.end(); I != E; ++I) |
| processInstruction(*I); |
| } |
| |
| void BytecodeWriter::outputSymbolTable(const SymbolTable &MST) { |
| BytecodeBlock FunctionBlock(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, std::ostream &Out) { |
| assert(C && "You can't write a null module!!"); |
| |
| std::deque<unsigned char> Buffer; |
| |
| // This object populates buffer for us... |
| BytecodeWriter BCW(Buffer, C); |
| |
| // Keep track of how much we've written... |
| BytesWritten += Buffer.size(); |
| |
| // 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. |
| // |
| std::deque<unsigned char>::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) { // Advanced by more than a byte of memory? |
| ++LastPtr; |
| break; |
| } |
| LastPtr = ThisPtr; |
| } |
| |
| // Write out the chunk... |
| Out.write((char*)ChunkPtr, LastPtr-ChunkPtr); |
| } |
| |
| Out.flush(); |
| } |