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	- Null values are implicitly encoded instead of explicitly, this makes
    things more compact!
  - More compactly represent ConstantPointerRefs
  - Bytecode files are represented as:
      Header|GlobalTypes|GlobalVars/Function Protos|Constants|Functions|SymTab
    instead of
      Header|GlobalTypes|Constants|GlobalVars/Function Protos|Functions|SymTab
    which makes a lot of things simpler.
Writer changes:
  - We now explictly encode versioning information in the bytecode files.
  - This allows new code to read bytecode files produced by old code, but
    new bytecode files can have enhancements such as the above.  Although this
    makes the reader a bit more complex (having to deal with old formats), the
    writer only needs to be able to produce the most recent version.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5749 91177308-0d34-0410-b5e6-96231b3b80d8
		
	
		
			
				
	
	
		
			77 lines
		
	
	
		
			2.4 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			77 lines
		
	
	
		
			2.4 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
//===-- WriterInternals.h - Data structures shared by the Writer -*- C++ -*--=//
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//
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// This header defines the interface used between components of the bytecode
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// writer.
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//
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// Note that the performance of this library is not terribly important, because
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// it shouldn't be used by JIT type applications... so it is not a huge focus
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// at least.  :)
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_BYTECODE_WRITER_WRITERINTERNALS_H
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#define LLVM_LIB_BYTECODE_WRITER_WRITERINTERNALS_H
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#include "llvm/Bytecode/Writer.h"
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#include "llvm/Bytecode/Format.h"
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#include "llvm/Bytecode/Primitives.h"
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#include "llvm/SlotCalculator.h"
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#include "llvm/Instruction.h"
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class BytecodeWriter {
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  std::deque<unsigned char> &Out;
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  SlotCalculator Table;
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public:
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  BytecodeWriter(std::deque<unsigned char> &o, const Module *M);
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protected:
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  void outputConstants(bool isFunction);
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  void outputFunction(const Function *F);
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  void processBasicBlock(const BasicBlock &BB);
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  void processInstruction(const Instruction &I);
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private :
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  inline void outputSignature() {
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    static const unsigned char *Sig =  (const unsigned char*)"llvm";
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    Out.insert(Out.end(), Sig, Sig+4); // output the bytecode signature...
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  }
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  void outputModuleInfoBlock(const Module *C);
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  void outputSymbolTable(const SymbolTable &ST);
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  void outputConstantsInPlane(const std::vector<const Value*> &Plane,
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                              unsigned StartNo);
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  bool outputConstant(const Constant *CPV);
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  void outputType(const Type *T);
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};
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// BytecodeBlock - Little helper class that helps us do backpatching of bytecode
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// block sizes really easily.  It backpatches when it goes out of scope.
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//
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class BytecodeBlock {
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  unsigned Loc;
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  std::deque<unsigned char> &Out;
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  BytecodeBlock(const BytecodeBlock &);   // do not implement
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  void operator=(const BytecodeBlock &);  // do not implement
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public:
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  inline BytecodeBlock(unsigned ID, std::deque<unsigned char> &o) : Out(o) {
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    output(ID, Out);
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    output((unsigned)0, Out);         // Reserve the space for the block size...
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    Loc = Out.size();
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  }
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  inline ~BytecodeBlock() {           // Do backpatch when block goes out
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                                      // of scope...
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    //cerr << "OldLoc = " << Loc << " NewLoc = " << NewLoc << " diff = "
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    //     << (NewLoc-Loc) << endl;
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    output((unsigned)(Out.size()-Loc), Out, (int)Loc-4);
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    align32(Out);  // Blocks must ALWAYS be aligned
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  }
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};
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#endif
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