1 //===---- TargetInfo.h - Encapsulate target details -------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // These classes wrap the information about a call or function
11 // definition used to handle ABI compliancy.
13 //===----------------------------------------------------------------------===//
15 #ifndef CLANG_CODEGEN_TARGETINFO_H
16 #define CLANG_CODEGEN_TARGETINFO_H
18 #include "clang/Basic/LLVM.h"
19 #include "clang/AST/Type.h"
20 #include "llvm/ADT/StringRef.h"
34 class CodeGenFunction;
37 /// TargetCodeGenInfo - This class organizes various target-specific
38 /// codegeneration issues, like target-specific attributes, builtins and so
40 class TargetCodeGenInfo {
43 // WARNING: Acquires the ownership of ABIInfo.
44 TargetCodeGenInfo(ABIInfo *info = 0):Info(info) { }
45 virtual ~TargetCodeGenInfo();
47 /// getABIInfo() - Returns ABI info helper for the target.
48 const ABIInfo& getABIInfo() const { return *Info; }
50 /// SetTargetAttributes - Provides a convenient hook to handle extra
51 /// target-specific attributes for the given global.
52 virtual void SetTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
53 CodeGen::CodeGenModule &M) const { }
55 /// Determines the size of struct _Unwind_Exception on this platform,
56 /// in 8-bit units. The Itanium ABI defines this as:
57 /// struct _Unwind_Exception {
58 /// uint64 exception_class;
59 /// _Unwind_Exception_Cleanup_Fn exception_cleanup;
63 virtual unsigned getSizeOfUnwindException() const;
65 /// Controls whether __builtin_extend_pointer should sign-extend
66 /// pointers to uint64_t or zero-extend them (the default). Has
67 /// no effect for targets:
68 /// - that have 64-bit pointers, or
69 /// - that cannot address through registers larger than pointers, or
70 /// - that implicitly ignore/truncate the top bits when addressing
71 /// through such registers.
72 virtual bool extendPointerWithSExt() const { return false; }
74 /// Determines the DWARF register number for the stack pointer, for
75 /// exception-handling purposes. Implements __builtin_dwarf_sp_column.
77 /// Returns -1 if the operation is unsupported by this target.
78 virtual int getDwarfEHStackPointer(CodeGen::CodeGenModule &M) const {
82 /// Initializes the given DWARF EH register-size table, a char*.
83 /// Implements __builtin_init_dwarf_reg_size_table.
85 /// Returns true if the operation is unsupported by this target.
86 virtual bool initDwarfEHRegSizeTable(CodeGen::CodeGenFunction &CGF,
87 llvm::Value *Address) const {
91 /// Performs the code-generation required to convert a return
92 /// address as stored by the system into the actual address of the
93 /// next instruction that will be executed.
95 /// Used by __builtin_extract_return_addr().
96 virtual llvm::Value *decodeReturnAddress(CodeGen::CodeGenFunction &CGF,
97 llvm::Value *Address) const {
101 /// Performs the code-generation required to convert the address
102 /// of an instruction into a return address suitable for storage
103 /// by the system in a return slot.
105 /// Used by __builtin_frob_return_addr().
106 virtual llvm::Value *encodeReturnAddress(CodeGen::CodeGenFunction &CGF,
107 llvm::Value *Address) const {
111 virtual llvm::Type* adjustInlineAsmType(CodeGen::CodeGenFunction &CGF,
112 StringRef Constraint,
113 llvm::Type* Ty) const {
117 /// Retrieve the address of a function to call immediately before
118 /// calling objc_retainAutoreleasedReturnValue. The
119 /// implementation of objc_autoreleaseReturnValue sniffs the
120 /// instruction stream following its return address to decide
121 /// whether it's a call to objc_retainAutoreleasedReturnValue.
122 /// This can be prohibitively expensive, depending on the
123 /// relocation model, and so on some targets it instead sniffs for
124 /// a particular instruction sequence. This functions returns
125 /// that instruction sequence in inline assembly, which will be
126 /// empty if none is required.
127 virtual StringRef getARCRetainAutoreleasedReturnValueMarker() const {
131 /// Determine whether a call to an unprototyped functions under
132 /// the given calling convention should use the variadic
133 /// convention or the non-variadic convention.
135 /// There's a good reason to make a platform's variadic calling
136 /// convention be different from its non-variadic calling
137 /// convention: the non-variadic arguments can be passed in
138 /// registers (better for performance), and the variadic arguments
139 /// can be passed on the stack (also better for performance). If
140 /// this is done, however, unprototyped functions *must* use the
141 /// non-variadic convention, because C99 states that a call
142 /// through an unprototyped function type must succeed if the
143 /// function was defined with a non-variadic prototype with
144 /// compatible parameters. Therefore, splitting the conventions
145 /// makes it impossible to call a variadic function through an
146 /// unprototyped type. Since function prototypes came out in the
147 /// late 1970s, this is probably an acceptable trade-off.
148 /// Nonetheless, not all platforms are willing to make it, and in
149 /// particularly x86-64 bends over backwards to make the
150 /// conventions compatible.
152 /// The default is false. This is correct whenever:
153 /// - the conventions are exactly the same, because it does not
154 /// matter and the resulting IR will be somewhat prettier in
155 /// certain cases; or
156 /// - the conventions are substantively different in how they pass
157 /// arguments, because in this case using the variadic convention
158 /// will lead to C99 violations.
159 /// It is not necessarily correct when arguments are passed in the
160 /// same way and some out-of-band information is passed for the
161 /// benefit of variadic callees, as is the case for x86-64.
162 /// In this case the ABI should be consulted.
163 virtual bool isNoProtoCallVariadic(CallingConv CC) const;
167 #endif // CLANG_CODEGEN_TARGETINFO_H