1 //===----- ABIInfo.h - ABI information access & encapsulation ---*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #ifndef LLVM_CLANG_LIB_CODEGEN_ABIINFO_H
10 #define LLVM_CLANG_LIB_CODEGEN_ABIINFO_H
11 
12 #include "clang/AST/CharUnits.h"
13 #include "clang/AST/Type.h"
14 #include "llvm/IR/CallingConv.h"
15 #include "llvm/IR/Type.h"
16 
17 namespace llvm {
18   class Value;
19   class LLVMContext;
20   class DataLayout;
21   class Type;
22 }
23 
24 namespace clang {
25   class ASTContext;
26   class CodeGenOptions;
27   class TargetInfo;
28 
29 namespace CodeGen {
30   class ABIArgInfo;
31   class Address;
32   class CGCXXABI;
33   class CGFunctionInfo;
34   class CodeGenFunction;
35   class CodeGenTypes;
36 
37   // FIXME: All of this stuff should be part of the target interface
38   // somehow. It is currently here because it is not clear how to factor
39   // the targets to support this, since the Targets currently live in a
40   // layer below types n'stuff.
41 
42 
43   /// ABIInfo - Target specific hooks for defining how a type should be
44   /// passed or returned from functions.
45   class ABIInfo {
46   protected:
47     CodeGen::CodeGenTypes &CGT;
48     llvm::CallingConv::ID RuntimeCC;
49   public:
50     ABIInfo(CodeGen::CodeGenTypes &cgt)
51         : CGT(cgt), RuntimeCC(llvm::CallingConv::C) {}
52 
53     virtual ~ABIInfo();
54 
55     virtual bool allowBFloatArgsAndRet() const { return false; }
56 
57     CodeGen::CGCXXABI &getCXXABI() const;
58     ASTContext &getContext() const;
59     llvm::LLVMContext &getVMContext() const;
60     const llvm::DataLayout &getDataLayout() const;
61     const TargetInfo &getTarget() const;
62     const CodeGenOptions &getCodeGenOpts() const;
63 
64     /// Return the calling convention to use for system runtime
65     /// functions.
66     llvm::CallingConv::ID getRuntimeCC() const {
67       return RuntimeCC;
68     }
69 
70     virtual void computeInfo(CodeGen::CGFunctionInfo &FI) const = 0;
71 
72     /// EmitVAArg - Emit the target dependent code to load a value of
73     /// \arg Ty from the va_list pointed to by \arg VAListAddr.
74 
75     // FIXME: This is a gaping layering violation if we wanted to drop
76     // the ABI information any lower than CodeGen. Of course, for
77     // VAArg handling it has to be at this level; there is no way to
78     // abstract this out.
79     virtual CodeGen::Address EmitVAArg(CodeGen::CodeGenFunction &CGF,
80                                        CodeGen::Address VAListAddr,
81                                        QualType Ty) const = 0;
82 
83     bool isAndroid() const;
84 
85     /// Emit the target dependent code to load a value of
86     /// \arg Ty from the \c __builtin_ms_va_list pointed to by \arg VAListAddr.
87     virtual CodeGen::Address EmitMSVAArg(CodeGen::CodeGenFunction &CGF,
88                                          CodeGen::Address VAListAddr,
89                                          QualType Ty) const;
90 
91     virtual bool isHomogeneousAggregateBaseType(QualType Ty) const;
92 
93     virtual bool isHomogeneousAggregateSmallEnough(const Type *Base,
94                                                    uint64_t Members) const;
95     virtual bool isZeroLengthBitfieldPermittedInHomogeneousAggregate() const;
96 
97     bool isHomogeneousAggregate(QualType Ty, const Type *&Base,
98                                 uint64_t &Members) const;
99 
100     // Implement the Type::IsPromotableIntegerType for ABI specific needs. The
101     // only difference is that this considers bit-precise integer types as well.
102     bool isPromotableIntegerTypeForABI(QualType Ty) const;
103 
104     /// A convenience method to return an indirect ABIArgInfo with an
105     /// expected alignment equal to the ABI alignment of the given type.
106     CodeGen::ABIArgInfo
107     getNaturalAlignIndirect(QualType Ty, bool ByVal = true,
108                             bool Realign = false,
109                             llvm::Type *Padding = nullptr) const;
110 
111     CodeGen::ABIArgInfo
112     getNaturalAlignIndirectInReg(QualType Ty, bool Realign = false) const;
113   };
114 
115   /// Target specific hooks for defining how a type should be passed or returned
116   /// from functions with one of the Swift calling conventions.
117   class SwiftABIInfo {
118   protected:
119     CodeGenTypes &CGT;
120     bool SwiftErrorInRegister;
121 
122   public:
123     SwiftABIInfo(CodeGen::CodeGenTypes &CGT, bool SwiftErrorInRegister)
124         : CGT(CGT), SwiftErrorInRegister(SwiftErrorInRegister) {}
125 
126     virtual ~SwiftABIInfo();
127 
128     /// Returns true if an aggregate which expands to the given type sequence
129     /// should be passed / returned indirectly.
130     virtual bool shouldPassIndirectly(ArrayRef<llvm::Type *> ComponentTys,
131                                       bool AsReturnValue) const;
132 
133     /// Returns true if the given vector type is legal from Swift's calling
134     /// convention perspective.
135     virtual bool isLegalVectorType(CharUnits VectorSize, llvm::Type *EltTy,
136                                    unsigned NumElts) const;
137 
138     /// Returns true if swifterror is lowered to a register by the target ABI.
139     bool isSwiftErrorInRegister() const { return SwiftErrorInRegister; };
140   };
141 }  // end namespace CodeGen
142 }  // end namespace clang
143 
144 #endif
145