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      1 //===----- ABIInfo.h - ABI information access & encapsulation ---*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 
     10 #ifndef CLANG_CODEGEN_ABIINFO_H
     11 #define CLANG_CODEGEN_ABIINFO_H
     12 
     13 #include "clang/AST/Type.h"
     14 #include "llvm/Type.h"
     15 
     16 namespace llvm {
     17   class Value;
     18   class LLVMContext;
     19   class TargetData;
     20 }
     21 
     22 namespace clang {
     23   class ASTContext;
     24 
     25   namespace CodeGen {
     26     class CGFunctionInfo;
     27     class CodeGenFunction;
     28     class CodeGenTypes;
     29   }
     30 
     31   // FIXME: All of this stuff should be part of the target interface
     32   // somehow. It is currently here because it is not clear how to factor
     33   // the targets to support this, since the Targets currently live in a
     34   // layer below types n'stuff.
     35 
     36   /// ABIArgInfo - Helper class to encapsulate information about how a
     37   /// specific C type should be passed to or returned from a function.
     38   class ABIArgInfo {
     39   public:
     40     enum Kind {
     41       /// Direct - Pass the argument directly using the normal converted LLVM
     42       /// type, or by coercing to another specified type stored in
     43       /// 'CoerceToType').  If an offset is specified (in UIntData), then the
     44       /// argument passed is offset by some number of bytes in the memory
     45       /// representation. A dummy argument is emitted before the real argument
     46       /// if the specified type stored in "PaddingType" is not zero.
     47       Direct,
     48 
     49       /// Extend - Valid only for integer argument types. Same as 'direct'
     50       /// but also emit a zero/sign extension attribute.
     51       Extend,
     52 
     53       /// Indirect - Pass the argument indirectly via a hidden pointer
     54       /// with the specified alignment (0 indicates default alignment).
     55       Indirect,
     56 
     57       /// Ignore - Ignore the argument (treat as void). Useful for void and
     58       /// empty structs.
     59       Ignore,
     60 
     61       /// Expand - Only valid for aggregate argument types. The structure should
     62       /// be expanded into consecutive arguments for its constituent fields.
     63       /// Currently expand is only allowed on structures whose fields
     64       /// are all scalar types or are themselves expandable types.
     65       Expand,
     66 
     67       KindFirst=Direct, KindLast=Expand
     68     };
     69 
     70   private:
     71     Kind TheKind;
     72     llvm::Type *TypeData;
     73     llvm::Type *PaddingType; // Currently allowed only for Direct.
     74     unsigned UIntData;
     75     bool BoolData0;
     76     bool BoolData1;
     77 
     78     ABIArgInfo(Kind K, llvm::Type *TD=0, unsigned UI=0,
     79                bool B0 = false, bool B1 = false, llvm::Type* P = 0)
     80       : TheKind(K), TypeData(TD), PaddingType(P), UIntData(UI), BoolData0(B0),
     81         BoolData1(B1) {}
     82 
     83   public:
     84     ABIArgInfo() : TheKind(Direct), TypeData(0), UIntData(0) {}
     85 
     86     static ABIArgInfo getDirect(llvm::Type *T = 0, unsigned Offset = 0,
     87                                 llvm::Type *Padding = 0) {
     88       return ABIArgInfo(Direct, T, Offset, false, false, Padding);
     89     }
     90     static ABIArgInfo getExtend(llvm::Type *T = 0) {
     91       return ABIArgInfo(Extend, T, 0);
     92     }
     93     static ABIArgInfo getIgnore() {
     94       return ABIArgInfo(Ignore);
     95     }
     96     static ABIArgInfo getIndirect(unsigned Alignment, bool ByVal = true
     97                                   , bool Realign = false) {
     98       return ABIArgInfo(Indirect, 0, Alignment, ByVal, Realign);
     99     }
    100     static ABIArgInfo getExpand() {
    101       return ABIArgInfo(Expand);
    102     }
    103 
    104     Kind getKind() const { return TheKind; }
    105     bool isDirect() const { return TheKind == Direct; }
    106     bool isExtend() const { return TheKind == Extend; }
    107     bool isIgnore() const { return TheKind == Ignore; }
    108     bool isIndirect() const { return TheKind == Indirect; }
    109     bool isExpand() const { return TheKind == Expand; }
    110 
    111     bool canHaveCoerceToType() const {
    112       return TheKind == Direct || TheKind == Extend;
    113     }
    114 
    115     // Direct/Extend accessors
    116     unsigned getDirectOffset() const {
    117       assert((isDirect() || isExtend()) && "Not a direct or extend kind");
    118       return UIntData;
    119     }
    120 
    121     llvm::Type *getPaddingType() const {
    122       return PaddingType;
    123     }
    124 
    125     llvm::Type *getCoerceToType() const {
    126       assert(canHaveCoerceToType() && "Invalid kind!");
    127       return TypeData;
    128     }
    129 
    130     void setCoerceToType(llvm::Type *T) {
    131       assert(canHaveCoerceToType() && "Invalid kind!");
    132       TypeData = T;
    133     }
    134 
    135     // Indirect accessors
    136     unsigned getIndirectAlign() const {
    137       assert(TheKind == Indirect && "Invalid kind!");
    138       return UIntData;
    139     }
    140 
    141     bool getIndirectByVal() const {
    142       assert(TheKind == Indirect && "Invalid kind!");
    143       return BoolData0;
    144     }
    145 
    146     bool getIndirectRealign() const {
    147       assert(TheKind == Indirect && "Invalid kind!");
    148       return BoolData1;
    149     }
    150 
    151     void dump() const;
    152   };
    153 
    154   /// ABIInfo - Target specific hooks for defining how a type should be
    155   /// passed or returned from functions.
    156   class ABIInfo {
    157   public:
    158     CodeGen::CodeGenTypes &CGT;
    159 
    160     ABIInfo(CodeGen::CodeGenTypes &cgt) : CGT(cgt) {}
    161     virtual ~ABIInfo();
    162 
    163     ASTContext &getContext() const;
    164     llvm::LLVMContext &getVMContext() const;
    165     const llvm::TargetData &getTargetData() const;
    166 
    167     virtual void computeInfo(CodeGen::CGFunctionInfo &FI) const = 0;
    168 
    169     /// EmitVAArg - Emit the target dependent code to load a value of
    170     /// \arg Ty from the va_list pointed to by \arg VAListAddr.
    171 
    172     // FIXME: This is a gaping layering violation if we wanted to drop
    173     // the ABI information any lower than CodeGen. Of course, for
    174     // VAArg handling it has to be at this level; there is no way to
    175     // abstract this out.
    176     virtual llvm::Value *EmitVAArg(llvm::Value *VAListAddr, QualType Ty,
    177                                    CodeGen::CodeGenFunction &CGF) const = 0;
    178   };
    179 }  // end namespace clang
    180 
    181 #endif
    182