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 std::unique_ptr<ABIInfo> Info = nullptr; 47 48 public: 49 TargetCodeGenInfo(std::unique_ptr<ABIInfo> Info) : Info(std::move(Info)) {} 50 virtual ~TargetCodeGenInfo(); 51 52 /// getABIInfo() - Returns ABI info helper for the target. 53 const ABIInfo &getABIInfo() const { return *Info; } 54 55 /// setTargetAttributes - Provides a convenient hook to handle extra 56 /// target-specific attributes for the given global. 57 virtual void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV, 58 CodeGen::CodeGenModule &M) const {} 59 60 /// emitTargetMetadata - Provides a convenient hook to handle extra 61 /// target-specific metadata for the given globals. 62 virtual void emitTargetMetadata( 63 CodeGen::CodeGenModule &CGM, 64 const llvm::MapVector<GlobalDecl, StringRef> &MangledDeclNames) const {} 65 66 /// Any further codegen related checks that need to be done on a function call 67 /// in a target specific manner. 68 virtual void checkFunctionCallABI(CodeGenModule &CGM, SourceLocation CallLoc, 69 const FunctionDecl *Caller, 70 const FunctionDecl *Callee, 71 const CallArgList &Args) const {} 72 73 /// Determines the size of struct _Unwind_Exception on this platform, 74 /// in 8-bit units. The Itanium ABI defines this as: 75 /// struct _Unwind_Exception { 76 /// uint64 exception_class; 77 /// _Unwind_Exception_Cleanup_Fn exception_cleanup; 78 /// uint64 private_1; 79 /// uint64 private_2; 80 /// }; 81 virtual unsigned getSizeOfUnwindException() const; 82 83 /// Controls whether __builtin_extend_pointer should sign-extend 84 /// pointers to uint64_t or zero-extend them (the default). Has 85 /// no effect for targets: 86 /// - that have 64-bit pointers, or 87 /// - that cannot address through registers larger than pointers, or 88 /// - that implicitly ignore/truncate the top bits when addressing 89 /// through such registers. 90 virtual bool extendPointerWithSExt() const { return false; } 91 92 /// Determines the DWARF register number for the stack pointer, for 93 /// exception-handling purposes. Implements __builtin_dwarf_sp_column. 94 /// 95 /// Returns -1 if the operation is unsupported by this target. 96 virtual int getDwarfEHStackPointer(CodeGen::CodeGenModule &M) const { 97 return -1; 98 } 99 100 /// Initializes the given DWARF EH register-size table, a char*. 101 /// Implements __builtin_init_dwarf_reg_size_table. 102 /// 103 /// Returns true if the operation is unsupported by this target. 104 virtual bool initDwarfEHRegSizeTable(CodeGen::CodeGenFunction &CGF, 105 llvm::Value *Address) const { 106 return true; 107 } 108 109 /// Performs the code-generation required to convert a return 110 /// address as stored by the system into the actual address of the 111 /// next instruction that will be executed. 112 /// 113 /// Used by __builtin_extract_return_addr(). 114 virtual llvm::Value *decodeReturnAddress(CodeGen::CodeGenFunction &CGF, 115 llvm::Value *Address) const { 116 return Address; 117 } 118 119 /// Performs the code-generation required to convert the address 120 /// of an instruction into a return address suitable for storage 121 /// by the system in a return slot. 122 /// 123 /// Used by __builtin_frob_return_addr(). 124 virtual llvm::Value *encodeReturnAddress(CodeGen::CodeGenFunction &CGF, 125 llvm::Value *Address) const { 126 return Address; 127 } 128 129 /// Corrects the low-level LLVM type for a given constraint and "usual" 130 /// type. 131 /// 132 /// \returns A pointer to a new LLVM type, possibly the same as the original 133 /// on success; 0 on failure. 134 virtual llvm::Type *adjustInlineAsmType(CodeGen::CodeGenFunction &CGF, 135 StringRef Constraint, 136 llvm::Type *Ty) const { 137 return Ty; 138 } 139 140 /// Adds constraints and types for result registers. 141 virtual void addReturnRegisterOutputs( 142 CodeGen::CodeGenFunction &CGF, CodeGen::LValue ReturnValue, 143 std::string &Constraints, std::vector<llvm::Type *> &ResultRegTypes, 144 std::vector<llvm::Type *> &ResultTruncRegTypes, 145 std::vector<CodeGen::LValue> &ResultRegDests, std::string &AsmString, 146 unsigned NumOutputs) const {} 147 148 /// doesReturnSlotInterfereWithArgs - Return true if the target uses an 149 /// argument slot for an 'sret' type. 150 virtual bool doesReturnSlotInterfereWithArgs() const { return true; } 151 152 /// Retrieve the address of a function to call immediately before 153 /// calling objc_retainAutoreleasedReturnValue. The 154 /// implementation of objc_autoreleaseReturnValue sniffs the 155 /// instruction stream following its return address to decide 156 /// whether it's a call to objc_retainAutoreleasedReturnValue. 157 /// This can be prohibitively expensive, depending on the 158 /// relocation model, and so on some targets it instead sniffs for 159 /// a particular instruction sequence. This functions returns 160 /// that instruction sequence in inline assembly, which will be 161 /// empty if none is required. 162 virtual StringRef getARCRetainAutoreleasedReturnValueMarker() const { 163 return ""; 164 } 165 166 /// Determine whether a call to objc_retainAutoreleasedReturnValue or 167 /// objc_unsafeClaimAutoreleasedReturnValue should be marked as 'notail'. 168 virtual bool markARCOptimizedReturnCallsAsNoTail() const { return false; } 169 170 /// Return a constant used by UBSan as a signature to identify functions 171 /// possessing type information, or 0 if the platform is unsupported. 172 virtual llvm::Constant * 173 getUBSanFunctionSignature(CodeGen::CodeGenModule &CGM) const { 174 return nullptr; 175 } 176 177 /// Determine whether a call to an unprototyped functions under 178 /// the given calling convention should use the variadic 179 /// convention or the non-variadic convention. 180 /// 181 /// There's a good reason to make a platform's variadic calling 182 /// convention be different from its non-variadic calling 183 /// convention: the non-variadic arguments can be passed in 184 /// registers (better for performance), and the variadic arguments 185 /// can be passed on the stack (also better for performance). If 186 /// this is done, however, unprototyped functions *must* use the 187 /// non-variadic convention, because C99 states that a call 188 /// through an unprototyped function type must succeed if the 189 /// function was defined with a non-variadic prototype with 190 /// compatible parameters. Therefore, splitting the conventions 191 /// makes it impossible to call a variadic function through an 192 /// unprototyped type. Since function prototypes came out in the 193 /// late 1970s, this is probably an acceptable trade-off. 194 /// Nonetheless, not all platforms are willing to make it, and in 195 /// particularly x86-64 bends over backwards to make the 196 /// conventions compatible. 197 /// 198 /// The default is false. This is correct whenever: 199 /// - the conventions are exactly the same, because it does not 200 /// matter and the resulting IR will be somewhat prettier in 201 /// certain cases; or 202 /// - the conventions are substantively different in how they pass 203 /// arguments, because in this case using the variadic convention 204 /// will lead to C99 violations. 205 /// 206 /// However, some platforms make the conventions identical except 207 /// for passing additional out-of-band information to a variadic 208 /// function: for example, x86-64 passes the number of SSE 209 /// arguments in %al. On these platforms, it is desirable to 210 /// call unprototyped functions using the variadic convention so 211 /// that unprototyped calls to varargs functions still succeed. 212 /// 213 /// Relatedly, platforms which pass the fixed arguments to this: 214 /// A foo(B, C, D); 215 /// differently than they would pass them to this: 216 /// A foo(B, C, D, ...); 217 /// may need to adjust the debugger-support code in Sema to do the 218 /// right thing when calling a function with no know signature. 219 virtual bool isNoProtoCallVariadic(const CodeGen::CallArgList &args, 220 const FunctionNoProtoType *fnType) const; 221 222 /// Gets the linker options necessary to link a dependent library on this 223 /// platform. 224 virtual void getDependentLibraryOption(llvm::StringRef Lib, 225 llvm::SmallString<24> &Opt) const; 226 227 /// Gets the linker options necessary to detect object file mismatches on 228 /// this platform. 229 virtual void getDetectMismatchOption(llvm::StringRef Name, 230 llvm::StringRef Value, 231 llvm::SmallString<32> &Opt) const {} 232 233 /// Get LLVM calling convention for OpenCL kernel. 234 virtual unsigned getOpenCLKernelCallingConv() const; 235 236 /// Get target specific null pointer. 237 /// \param T is the LLVM type of the null pointer. 238 /// \param QT is the clang QualType of the null pointer. 239 /// \return ConstantPointerNull with the given type \p T. 240 /// Each target can override it to return its own desired constant value. 241 virtual llvm::Constant *getNullPointer(const CodeGen::CodeGenModule &CGM, 242 llvm::PointerType *T, QualType QT) const; 243 244 /// Get target favored AST address space of a global variable for languages 245 /// other than OpenCL and CUDA. 246 /// If \p D is nullptr, returns the default target favored address space 247 /// for global variable. 248 virtual LangAS getGlobalVarAddressSpace(CodeGenModule &CGM, 249 const VarDecl *D) const; 250 251 /// Get the AST address space for alloca. 252 virtual LangAS getASTAllocaAddressSpace() const { return LangAS::Default; } 253 254 /// Perform address space cast of an expression of pointer type. 255 /// \param V is the LLVM value to be casted to another address space. 256 /// \param SrcAddr is the language address space of \p V. 257 /// \param DestAddr is the targeted language address space. 258 /// \param DestTy is the destination LLVM pointer type. 259 /// \param IsNonNull is the flag indicating \p V is known to be non null. 260 virtual llvm::Value *performAddrSpaceCast(CodeGen::CodeGenFunction &CGF, 261 llvm::Value *V, LangAS SrcAddr, 262 LangAS DestAddr, llvm::Type *DestTy, 263 bool IsNonNull = false) const; 264 265 /// Perform address space cast of a constant expression of pointer type. 266 /// \param V is the LLVM constant to be casted to another address space. 267 /// \param SrcAddr is the language address space of \p V. 268 /// \param DestAddr is the targeted language address space. 269 /// \param DestTy is the destination LLVM pointer type. 270 virtual llvm::Constant *performAddrSpaceCast(CodeGenModule &CGM, 271 llvm::Constant *V, 272 LangAS SrcAddr, LangAS DestAddr, 273 llvm::Type *DestTy) const; 274 275 /// Get address space of pointer parameter for __cxa_atexit. 276 virtual LangAS getAddrSpaceOfCxaAtexitPtrParam() const { 277 return LangAS::Default; 278 } 279 280 /// Get the syncscope used in LLVM IR. 281 virtual llvm::SyncScope::ID getLLVMSyncScopeID(const LangOptions &LangOpts, 282 SyncScope Scope, 283 llvm::AtomicOrdering Ordering, 284 llvm::LLVMContext &Ctx) const; 285 286 /// Interface class for filling custom fields of a block literal for OpenCL. 287 class TargetOpenCLBlockHelper { 288 public: 289 typedef std::pair<llvm::Value *, StringRef> ValueTy; 290 TargetOpenCLBlockHelper() {} 291 virtual ~TargetOpenCLBlockHelper() {} 292 /// Get the custom field types for OpenCL blocks. 293 virtual llvm::SmallVector<llvm::Type *, 1> getCustomFieldTypes() = 0; 294 /// Get the custom field values for OpenCL blocks. 295 virtual llvm::SmallVector<ValueTy, 1> 296 getCustomFieldValues(CodeGenFunction &CGF, const CGBlockInfo &Info) = 0; 297 virtual bool areAllCustomFieldValuesConstant(const CGBlockInfo &Info) = 0; 298 /// Get the custom field values for OpenCL blocks if all values are LLVM 299 /// constants. 300 virtual llvm::SmallVector<llvm::Constant *, 1> 301 getCustomFieldValues(CodeGenModule &CGM, const CGBlockInfo &Info) = 0; 302 }; 303 virtual TargetOpenCLBlockHelper *getTargetOpenCLBlockHelper() const { 304 return nullptr; 305 } 306 307 /// Create an OpenCL kernel for an enqueued block. The kernel function is 308 /// a wrapper for the block invoke function with target-specific calling 309 /// convention and ABI as an OpenCL kernel. The wrapper function accepts 310 /// block context and block arguments in target-specific way and calls 311 /// the original block invoke function. 312 virtual llvm::Function * 313 createEnqueuedBlockKernel(CodeGenFunction &CGF, 314 llvm::Function *BlockInvokeFunc, 315 llvm::Value *BlockLiteral) const; 316 317 /// \return true if the target supports alias from the unmangled name to the 318 /// mangled name of functions declared within an extern "C" region and marked 319 /// as 'used', and having internal linkage. 320 virtual bool shouldEmitStaticExternCAliases() const { return true; } 321 322 virtual void setCUDAKernelCallingConvention(const FunctionType *&FT) const {} 323 324 /// Return the device-side type for the CUDA device builtin surface type. 325 virtual llvm::Type *getCUDADeviceBuiltinSurfaceDeviceType() const { 326 // By default, no change from the original one. 327 return nullptr; 328 } 329 /// Return the device-side type for the CUDA device builtin texture type. 330 virtual llvm::Type *getCUDADeviceBuiltinTextureDeviceType() const { 331 // By default, no change from the original one. 332 return nullptr; 333 } 334 335 /// Emit the device-side copy of the builtin surface type. 336 virtual bool emitCUDADeviceBuiltinSurfaceDeviceCopy(CodeGenFunction &CGF, 337 LValue Dst, 338 LValue Src) const { 339 // DO NOTHING by default. 340 return false; 341 } 342 /// Emit the device-side copy of the builtin texture type. 343 virtual bool emitCUDADeviceBuiltinTextureDeviceCopy(CodeGenFunction &CGF, 344 LValue Dst, 345 LValue Src) const { 346 // DO NOTHING by default. 347 return false; 348 } 349 }; 350 351 } // namespace CodeGen 352 } // namespace clang 353 354 #endif // LLVM_CLANG_LIB_CODEGEN_TARGETINFO_H 355