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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.
     46       Direct,
     47 
     48       /// Extend - Valid only for integer argument types. Same as 'direct'
     49       /// but also emit a zero/sign extension attribute.
     50       Extend,
     51 
     52       /// Indirect - Pass the argument indirectly via a hidden pointer
     53       /// with the specified alignment (0 indicates default alignment).
     54       Indirect,
     55 
     56       /// Ignore - Ignore the argument (treat as void). Useful for void and
     57       /// empty structs.
     58       Ignore,
     59 
     60       /// Expand - Only valid for aggregate argument types. The structure should
     61       /// be expanded into consecutive arguments for its constituent fields.
     62       /// Currently expand is only allowed on structures whose fields
     63       /// are all scalar types or are themselves expandable types.
     64       Expand,
     65 
     66       KindFirst=Direct, KindLast=Expand
     67     };
     68 
     69   private:
     70     Kind TheKind;
     71     llvm::Type *TypeData;
     72     unsigned UIntData;
     73     bool BoolData0;
     74     bool BoolData1;
     75 
     76     ABIArgInfo(Kind K, llvm::Type *TD=0,
     77                unsigned UI=0, bool B0 = false, bool B1 = false)
     78       : TheKind(K), TypeData(TD), UIntData(UI), BoolData0(B0), BoolData1(B1) {}
     79 
     80   public:
     81     ABIArgInfo() : TheKind(Direct), TypeData(0), UIntData(0) {}
     82 
     83     static ABIArgInfo getDirect(llvm::Type *T = 0, unsigned Offset = 0) {
     84       return ABIArgInfo(Direct, T, Offset);
     85     }
     86     static ABIArgInfo getExtend(llvm::Type *T = 0) {
     87       return ABIArgInfo(Extend, T, 0);
     88     }
     89     static ABIArgInfo getIgnore() {
     90       return ABIArgInfo(Ignore);
     91     }
     92     static ABIArgInfo getIndirect(unsigned Alignment, bool ByVal = true
     93                                   , bool Realign = false) {
     94       return ABIArgInfo(Indirect, 0, Alignment, ByVal, Realign);
     95     }
     96     static ABIArgInfo getExpand() {
     97       return ABIArgInfo(Expand);
     98     }
     99 
    100     Kind getKind() const { return TheKind; }
    101     bool isDirect() const { return TheKind == Direct; }
    102     bool isExtend() const { return TheKind == Extend; }
    103     bool isIgnore() const { return TheKind == Ignore; }
    104     bool isIndirect() const { return TheKind == Indirect; }
    105     bool isExpand() const { return TheKind == Expand; }
    106 
    107     bool canHaveCoerceToType() const {
    108       return TheKind == Direct || TheKind == Extend;
    109     }
    110 
    111     // Direct/Extend accessors
    112     unsigned getDirectOffset() const {
    113       assert((isDirect() || isExtend()) && "Not a direct or extend kind");
    114       return UIntData;
    115     }
    116     llvm::Type *getCoerceToType() const {
    117       assert(canHaveCoerceToType() && "Invalid kind!");
    118       return TypeData;
    119     }
    120 
    121     void setCoerceToType(llvm::Type *T) {
    122       assert(canHaveCoerceToType() && "Invalid kind!");
    123       TypeData = T;
    124     }
    125 
    126     // Indirect accessors
    127     unsigned getIndirectAlign() const {
    128       assert(TheKind == Indirect && "Invalid kind!");
    129       return UIntData;
    130     }
    131 
    132     bool getIndirectByVal() const {
    133       assert(TheKind == Indirect && "Invalid kind!");
    134       return BoolData0;
    135     }
    136 
    137     bool getIndirectRealign() const {
    138       assert(TheKind == Indirect && "Invalid kind!");
    139       return BoolData1;
    140     }
    141 
    142     void dump() const;
    143   };
    144 
    145   /// ABIInfo - Target specific hooks for defining how a type should be
    146   /// passed or returned from functions.
    147   class ABIInfo {
    148   public:
    149     CodeGen::CodeGenTypes &CGT;
    150 
    151     ABIInfo(CodeGen::CodeGenTypes &cgt) : CGT(cgt) {}
    152     virtual ~ABIInfo();
    153 
    154     ASTContext &getContext() const;
    155     llvm::LLVMContext &getVMContext() const;
    156     const llvm::TargetData &getTargetData() const;
    157 
    158     virtual void computeInfo(CodeGen::CGFunctionInfo &FI) const = 0;
    159 
    160     /// EmitVAArg - Emit the target dependent code to load a value of
    161     /// \arg Ty from the va_list pointed to by \arg VAListAddr.
    162 
    163     // FIXME: This is a gaping layering violation if we wanted to drop
    164     // the ABI information any lower than CodeGen. Of course, for
    165     // VAArg handling it has to be at this level; there is no way to
    166     // abstract this out.
    167     virtual llvm::Value *EmitVAArg(llvm::Value *VAListAddr, QualType Ty,
    168                                    CodeGen::CodeGenFunction &CGF) const = 0;
    169   };
    170 }  // end namespace clang
    171 
    172 #endif
    173