text: //===-- llvm/InlineAsm.h - Class to represent inline asm strings-*- C++ -*-===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  // This class represents the inline asm strings, which are Value*'s that are
  // used as the callee operand of call instructions.  InlineAsm's are uniqued
  // like constants, and created via InlineAsm::get(...).
  //
  //===----------------------------------------------------------------------===//
  
  #ifndef LLVM_INLINEASM_H
  #define LLVM_INLINEASM_H
  
  #include "llvm/Value.h"
  #include <vector>
  
  namespace llvm {
  
  class PointerType;
  class FunctionType;
  class Module;
  
  class InlineAsm : public Value {
    InlineAsm(const InlineAsm &);             // do not implement
    void operator=(const InlineAsm&);         // do not implement
  
    std::string AsmString, Constraints;
    bool HasSideEffects;
    bool IsAlignStack;
    
    InlineAsm(const FunctionType *Ty, StringRef AsmString,
              StringRef Constraints, bool hasSideEffects,
              bool isAlignStack = false);
    virtual ~InlineAsm();
  public:
  
    /// InlineAsm::get - Return the specified uniqued inline asm string.
    ///
    static InlineAsm *get(const FunctionType *Ty, StringRef AsmString,
                          StringRef Constraints, bool hasSideEffects,
                          bool isAlignStack = false);
    
    bool hasSideEffects() const { return HasSideEffects; }
    bool isAlignStack() const { return IsAlignStack; }
    
    /// getType - InlineAsm's are always pointers.
    ///
    const PointerType *getType() const {
      return reinterpret_cast<const PointerType*>(Value::getType());
    }
    
    /// getFunctionType - InlineAsm's are always pointers to functions.
    ///
    const FunctionType *getFunctionType() const;
    
    const std::string &getAsmString() const { return AsmString; }
    const std::string &getConstraintString() const { return Constraints; }
  
    /// Verify - This static method can be used by the parser to check to see if
    /// the specified constraint string is legal for the type.  This returns true
    /// if legal, false if not.
    ///
    static bool Verify(const FunctionType *Ty, StringRef Constraints);
  
    // Constraint String Parsing 
    enum ConstraintPrefix {
      isInput,            // 'x'
      isOutput,           // '=x'
      isClobber           // '~x'
    };
    
    struct ConstraintInfo {
      /// Type - The basic type of the constraint: input/output/clobber
      ///
      ConstraintPrefix Type;
      
      /// isEarlyClobber - "&": output operand writes result before inputs are all
      /// read.  This is only ever set for an output operand.
      bool isEarlyClobber; 
      
      /// MatchingInput - If this is not -1, this is an output constraint where an
      /// input constraint is required to match it (e.g. "0").  The value is the
      /// constraint number that matches this one (for example, if this is
      /// constraint #0 and constraint #4 has the value "0", this will be 4).
      signed char MatchingInput;
      
      /// hasMatchingInput - Return true if this is an output constraint that has
      /// a matching input constraint.
      bool hasMatchingInput() const { return MatchingInput != -1; }
      
      /// isCommutative - This is set to true for a constraint that is commutative
      /// with the next operand.
      bool isCommutative;
      
      /// isIndirect - True if this operand is an indirect operand.  This means
      /// that the address of the source or destination is present in the call
      /// instruction, instead of it being returned or passed in explicitly.  This
      /// is represented with a '*' in the asm string.
      bool isIndirect;
      
      /// Code - The constraint code, either the register name (in braces) or the
      /// constraint letter/number.
      std::vector<std::string> Codes;
      
      /// Parse - Analyze the specified string (e.g. "=*&{eax}") and fill in the
      /// fields in this structure.  If the constraint string is not understood,
      /// return true, otherwise return false.
      bool Parse(StringRef Str, 
                 std::vector<InlineAsm::ConstraintInfo> &ConstraintsSoFar);
    };
    
    /// ParseConstraints - Split up the constraint string into the specific
    /// constraints and their prefixes.  If this returns an empty vector, and if
    /// the constraint string itself isn't empty, there was an error parsing.
    static std::vector<ConstraintInfo> 
      ParseConstraints(StringRef ConstraintString);
    
    /// ParseConstraints - Parse the constraints of this inlineasm object, 
    /// returning them the same way that ParseConstraints(str) does.
    std::vector<ConstraintInfo> 
    ParseConstraints() const {
      return ParseConstraints(Constraints);
    }
    
    // Methods for support type inquiry through isa, cast, and dyn_cast:
    static inline bool classof(const InlineAsm *) { return true; }
    static inline bool classof(const Value *V) {
      return V->getValueID() == Value::InlineAsmVal;
    }
  
    /// getNumOperandRegisters - Extract the number of registers field from the
    /// inline asm operand flag.
    static unsigned getNumOperandRegisters(unsigned Flag) {
      return (Flag & 0xffff) >> 3;
    }
  
    /// isUseOperandTiedToDef - Return true if the flag of the inline asm
    /// operand indicates it is an use operand that's matched to a def operand.
    static bool isUseOperandTiedToDef(unsigned Flag, unsigned &Idx) {
      if ((Flag & 0x80000000) == 0)
        return false;
      Idx = (Flag & ~0x80000000) >> 16;
      return true;
    }
  
  
  };
  
  } // End llvm namespace
  
  #endif
  