lib/Bytecode/Writer/Writer.cpp - fp2-dev/platform/external/llvm - Gitiles

 //===-- Writer.cpp - Library for writing VM bytecode files -------*- C++ -*--=//
 //
 // 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'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/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 reemit 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();
 }
	//===-- Writer.cpp - Library for writing VM bytecode files -------- C++ ---=//
	//
	// 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'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/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 reemit 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();
	}