1 //===---- TargetInfo.h - Encapsulate target details -------------*- 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 // These classes wrap the information about a call or function 10 // definition used to handle ABI compliancy. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_CLANG_LIB_CODEGEN_TARGETINFO_H 15 #define LLVM_CLANG_LIB_CODEGEN_TARGETINFO_H 16 17 #include "CodeGenModule.h" 18 #include "CGValue.h" 19 #include "clang/AST/Type.h" 20 #include "clang/Basic/LLVM.h" 21 #include "clang/Basic/SyncScope.h" 22 #include "llvm/ADT/SmallString.h" 23 #include "llvm/ADT/StringRef.h" 24 25 namespace llvm { 26 class Constant; 27 class GlobalValue; 28 class Type; 29 class Value; 30 } 31 32 namespace clang { 33 class Decl; 34 35 namespace CodeGen { 36 class ABIInfo; 37 class CallArgList; 38 class CodeGenFunction; 39 class CGBlockInfo; 40 class CGFunctionInfo; 41 42 /// TargetCodeGenInfo - This class organizes various target-specific 43 /// codegeneration issues, like target-specific attributes, builtins and so 44 /// on. 45 class TargetCodeGenInfo { 46 ABIInfo *Info; 47 48 public: 49 // WARNING: Acquires the ownership of ABIInfo. 50 TargetCodeGenInfo(ABIInfo *info = nullptr) : Info(info) {} 51 virtual ~TargetCodeGenInfo(); 52 53 /// getABIInfo() - Returns ABI info helper for the target. 54 const ABIInfo &getABIInfo() const { return *Info; } 55 56 /// setTargetAttributes - Provides a convenient hook to handle extra 57 /// target-specific attributes for the given global. 58 virtual void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV, 59 CodeGen::CodeGenModule &M) const {} 60 61 /// emitTargetMD - Provides a convenient hook to handle extra 62 /// target-specific metadata for the given global. 63 virtual void emitTargetMD(const Decl *D, llvm::GlobalValue *GV, 64 CodeGen::CodeGenModule &M) const {} 65 66 /// Determines the size of struct _Unwind_Exception on this platform, 67 /// in 8-bit units. The Itanium ABI defines this as: 68 /// struct _Unwind_Exception { 69 /// uint64 exception_class; 70 /// _Unwind_Exception_Cleanup_Fn exception_cleanup; 71 /// uint64 private_1; 72 /// uint64 private_2; 73 /// }; 74 virtual unsigned getSizeOfUnwindException() const; 75 76 /// Controls whether __builtin_extend_pointer should sign-extend 77 /// pointers to uint64_t or zero-extend them (the default). Has 78 /// no effect for targets: 79 /// - that have 64-bit pointers, or 80 /// - that cannot address through registers larger than pointers, or 81 /// - that implicitly ignore/truncate the top bits when addressing 82 /// through such registers. 83 virtual bool extendPointerWithSExt() const { return false; } 84 85 /// Determines the DWARF register number for the stack pointer, for 86 /// exception-handling purposes. Implements __builtin_dwarf_sp_column. 87 /// 88 /// Returns -1 if the operation is unsupported by this target. 89 virtual int getDwarfEHStackPointer(CodeGen::CodeGenModule &M) const { 90 return -1; 91 } 92 93 /// Initializes the given DWARF EH register-size table, a char*. 94 /// Implements __builtin_init_dwarf_reg_size_table. 95 /// 96 /// Returns true if the operation is unsupported by this target. 97 virtual bool initDwarfEHRegSizeTable(CodeGen::CodeGenFunction &CGF, 98 llvm::Value *Address) const { 99 return true; 100 } 101 102 /// Performs the code-generation required to convert a return 103 /// address as stored by the system into the actual address of the 104 /// next instruction that will be executed. 105 /// 106 /// Used by __builtin_extract_return_addr(). 107 virtual llvm::Value *decodeReturnAddress(CodeGen::CodeGenFunction &CGF, 108 llvm::Value *Address) const { 109 return Address; 110 } 111 112 /// Performs the code-generation required to convert the address 113 /// of an instruction into a return address suitable for storage 114 /// by the system in a return slot. 115 /// 116 /// Used by __builtin_frob_return_addr(). 117 virtual llvm::Value *encodeReturnAddress(CodeGen::CodeGenFunction &CGF, 118 llvm::Value *Address) const { 119 return Address; 120 } 121 122 /// Corrects the low-level LLVM type for a given constraint and "usual" 123 /// type. 124 /// 125 /// \returns A pointer to a new LLVM type, possibly the same as the original 126 /// on success; 0 on failure. 127 virtual llvm::Type *adjustInlineAsmType(CodeGen::CodeGenFunction &CGF, 128 StringRef Constraint, 129 llvm::Type *Ty) const { 130 return Ty; 131 } 132 133 /// Adds constraints and types for result registers. 134 virtual void addReturnRegisterOutputs( 135 CodeGen::CodeGenFunction &CGF, CodeGen::LValue ReturnValue, 136 std::string &Constraints, std::vector<llvm::Type *> &ResultRegTypes, 137 std::vector<llvm::Type *> &ResultTruncRegTypes, 138 std::vector<CodeGen::LValue> &ResultRegDests, std::string &AsmString, 139 unsigned NumOutputs) const {} 140 141 /// doesReturnSlotInterfereWithArgs - Return true if the target uses an 142 /// argument slot for an 'sret' type. 143 virtual bool doesReturnSlotInterfereWithArgs() const { return true; } 144 145 /// Retrieve the address of a function to call immediately before 146 /// calling objc_retainAutoreleasedReturnValue. The 147 /// implementation of objc_autoreleaseReturnValue sniffs the 148 /// instruction stream following its return address to decide 149 /// whether it's a call to objc_retainAutoreleasedReturnValue. 150 /// This can be prohibitively expensive, depending on the 151 /// relocation model, and so on some targets it instead sniffs for 152 /// a particular instruction sequence. This functions returns 153 /// that instruction sequence in inline assembly, which will be 154 /// empty if none is required. 155 virtual StringRef getARCRetainAutoreleasedReturnValueMarker() const { 156 return ""; 157 } 158 159 /// Determine whether a call to objc_retainAutoreleasedReturnValue should be 160 /// marked as 'notail'. 161 virtual bool shouldSuppressTailCallsOfRetainAutoreleasedReturnValue() const { 162 return false; 163 } 164 165 /// Return a constant used by UBSan as a signature to identify functions 166 /// possessing type information, or 0 if the platform is unsupported. 167 virtual llvm::Constant * 168 getUBSanFunctionSignature(CodeGen::CodeGenModule &CGM) const { 169 return nullptr; 170 } 171 172 /// Determine whether a call to an unprototyped functions under 173 /// the given calling convention should use the variadic 174 /// convention or the non-variadic convention. 175 /// 176 /// There's a good reason to make a platform's variadic calling 177 /// convention be different from its non-variadic calling 178 /// convention: the non-variadic arguments can be passed in 179 /// registers (better for performance), and the variadic arguments 180 /// can be passed on the stack (also better for performance). If 181 /// this is done, however, unprototyped functions *must* use the 182 /// non-variadic convention, because C99 states that a call 183 /// through an unprototyped function type must succeed if the 184 /// function was defined with a non-variadic prototype with 185 /// compatible parameters. Therefore, splitting the conventions 186 /// makes it impossible to call a variadic function through an 187 /// unprototyped type. Since function prototypes came out in the 188 /// late 1970s, this is probably an acceptable trade-off. 189 /// Nonetheless, not all platforms are willing to make it, and in 190 /// particularly x86-64 bends over backwards to make the 191 /// conventions compatible. 192 /// 193 /// The default is false. This is correct whenever: 194 /// - the conventions are exactly the same, because it does not 195 /// matter and the resulting IR will be somewhat prettier in 196 /// certain cases; or 197 /// - the conventions are substantively different in how they pass 198 /// arguments, because in this case using the variadic convention 199 /// will lead to C99 violations. 200 /// 201 /// However, some platforms make the conventions identical except 202 /// for passing additional out-of-band information to a variadic 203 /// function: for example, x86-64 passes the number of SSE 204 /// arguments in %al. On these platforms, it is desirable to 205 /// call unprototyped functions using the variadic convention so 206 /// that unprototyped calls to varargs functions still succeed. 207 /// 208 /// Relatedly, platforms which pass the fixed arguments to this: 209 /// A foo(B, C, D); 210 /// differently than they would pass them to this: 211 /// A foo(B, C, D, ...); 212 /// may need to adjust the debugger-support code in Sema to do the 213 /// right thing when calling a function with no know signature. 214 virtual bool isNoProtoCallVariadic(const CodeGen::CallArgList &args, 215 const FunctionNoProtoType *fnType) const; 216 217 /// Gets the linker options necessary to link a dependent library on this 218 /// platform. 219 virtual void getDependentLibraryOption(llvm::StringRef Lib, 220 llvm::SmallString<24> &Opt) const; 221 222 /// Gets the linker options necessary to detect object file mismatches on 223 /// this platform. 224 virtual void getDetectMismatchOption(llvm::StringRef Name, 225 llvm::StringRef Value, 226 llvm::SmallString<32> &Opt) const {} 227 228 /// Get LLVM calling convention for OpenCL kernel. 229 virtual unsigned getOpenCLKernelCallingConv() const; 230 231 /// Get target specific null pointer. 232 /// \param T is the LLVM type of the null pointer. 233 /// \param QT is the clang QualType of the null pointer. 234 /// \return ConstantPointerNull with the given type \p T. 235 /// Each target can override it to return its own desired constant value. 236 virtual llvm::Constant *getNullPointer(const CodeGen::CodeGenModule &CGM, 237 llvm::PointerType *T, QualType QT) const; 238 239 /// Get target favored AST address space of a global variable for languages 240 /// other than OpenCL and CUDA. 241 /// If \p D is nullptr, returns the default target favored address space 242 /// for global variable. 243 virtual LangAS getGlobalVarAddressSpace(CodeGenModule &CGM, 244 const VarDecl *D) const; 245 246 /// Get the AST address space for alloca. 247 virtual LangAS getASTAllocaAddressSpace() const { return LangAS::Default; } 248 249 /// Perform address space cast of an expression of pointer type. 250 /// \param V is the LLVM value to be casted to another address space. 251 /// \param SrcAddr is the language address space of \p V. 252 /// \param DestAddr is the targeted language address space. 253 /// \param DestTy is the destination LLVM pointer type. 254 /// \param IsNonNull is the flag indicating \p V is known to be non null. 255 virtual llvm::Value *performAddrSpaceCast(CodeGen::CodeGenFunction &CGF, 256 llvm::Value *V, LangAS SrcAddr, 257 LangAS DestAddr, llvm::Type *DestTy, 258 bool IsNonNull = false) const; 259 260 /// Perform address space cast of a constant expression of pointer type. 261 /// \param V is the LLVM constant to be casted to another address space. 262 /// \param SrcAddr is the language address space of \p V. 263 /// \param DestAddr is the targeted language address space. 264 /// \param DestTy is the destination LLVM pointer type. 265 virtual llvm::Constant *performAddrSpaceCast(CodeGenModule &CGM, 266 llvm::Constant *V, 267 LangAS SrcAddr, LangAS DestAddr, 268 llvm::Type *DestTy) const; 269 270 /// Get address space of pointer parameter for __cxa_atexit. 271 virtual LangAS getAddrSpaceOfCxaAtexitPtrParam() const { 272 return LangAS::Default; 273 } 274 275 /// Get the syncscope used in LLVM IR. 276 virtual llvm::SyncScope::ID getLLVMSyncScopeID(const LangOptions &LangOpts, 277 SyncScope Scope, 278 llvm::AtomicOrdering Ordering, 279 llvm::LLVMContext &Ctx) const; 280 281 /// Interface class for filling custom fields of a block literal for OpenCL. 282 class TargetOpenCLBlockHelper { 283 public: 284 typedef std::pair<llvm::Value *, StringRef> ValueTy; 285 TargetOpenCLBlockHelper() {} 286 virtual ~TargetOpenCLBlockHelper() {} 287 /// Get the custom field types for OpenCL blocks. 288 virtual llvm::SmallVector<llvm::Type *, 1> getCustomFieldTypes() = 0; 289 /// Get the custom field values for OpenCL blocks. 290 virtual llvm::SmallVector<ValueTy, 1> 291 getCustomFieldValues(CodeGenFunction &CGF, const CGBlockInfo &Info) = 0; 292 virtual bool areAllCustomFieldValuesConstant(const CGBlockInfo &Info) = 0; 293 /// Get the custom field values for OpenCL blocks if all values are LLVM 294 /// constants. 295 virtual llvm::SmallVector<llvm::Constant *, 1> 296 getCustomFieldValues(CodeGenModule &CGM, const CGBlockInfo &Info) = 0; 297 }; 298 virtual TargetOpenCLBlockHelper *getTargetOpenCLBlockHelper() const { 299 return nullptr; 300 } 301 302 /// Create an OpenCL kernel for an enqueued block. The kernel function is 303 /// a wrapper for the block invoke function with target-specific calling 304 /// convention and ABI as an OpenCL kernel. The wrapper function accepts 305 /// block context and block arguments in target-specific way and calls 306 /// the original block invoke function. 307 virtual llvm::Function * 308 createEnqueuedBlockKernel(CodeGenFunction &CGF, 309 llvm::Function *BlockInvokeFunc, 310 llvm::Value *BlockLiteral) const; 311 312 /// \return true if the target supports alias from the unmangled name to the 313 /// mangled name of functions declared within an extern "C" region and marked 314 /// as 'used', and having internal linkage. 315 virtual bool shouldEmitStaticExternCAliases() const { return true; } 316 317 virtual void setCUDAKernelCallingConvention(const FunctionType *&FT) const {} 318 }; 319 320 } // namespace CodeGen 321 } // namespace clang 322 323 #endif // LLVM_CLANG_LIB_CODEGEN_TARGETINFO_H 324