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 "CGBuilder.h" 18 #include "CodeGenModule.h" 19 #include "CGValue.h" 20 #include "clang/AST/Type.h" 21 #include "clang/Basic/LLVM.h" 22 #include "clang/Basic/SyncScope.h" 23 #include "llvm/ADT/SmallString.h" 24 #include "llvm/ADT/StringRef.h" 25 26 namespace llvm { 27 class Constant; 28 class GlobalValue; 29 class Type; 30 class Value; 31 } 32 33 namespace clang { 34 class Decl; 35 36 namespace CodeGen { 37 class ABIInfo; 38 class CallArgList; 39 class CodeGenFunction; 40 class CGBlockInfo; 41 class SwiftABIInfo; 42 43 /// TargetCodeGenInfo - This class organizes various target-specific 44 /// codegeneration issues, like target-specific attributes, builtins and so 45 /// on. 46 class TargetCodeGenInfo { 47 std::unique_ptr<ABIInfo> Info; 48 49 protected: 50 // Target hooks supporting Swift calling conventions. The target must 51 // initialize this field if it claims to support these calling conventions 52 // by returning true from TargetInfo::checkCallingConvention for them. 53 std::unique_ptr<SwiftABIInfo> SwiftInfo; 54 55 public: 56 TargetCodeGenInfo(std::unique_ptr<ABIInfo> Info); 57 virtual ~TargetCodeGenInfo(); 58 59 /// getABIInfo() - Returns ABI info helper for the target. 60 const ABIInfo &getABIInfo() const { return *Info; } 61 62 /// Returns Swift ABI info helper for the target. 63 const SwiftABIInfo &getSwiftABIInfo() const { 64 assert(SwiftInfo && "Swift ABI info has not been initialized"); 65 return *SwiftInfo; 66 } 67 68 /// setTargetAttributes - Provides a convenient hook to handle extra 69 /// target-specific attributes for the given global. 70 virtual void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV, 71 CodeGen::CodeGenModule &M) const {} 72 73 /// emitTargetMetadata - Provides a convenient hook to handle extra 74 /// target-specific metadata for the given globals. 75 virtual void emitTargetMetadata( 76 CodeGen::CodeGenModule &CGM, 77 const llvm::MapVector<GlobalDecl, StringRef> &MangledDeclNames) const {} 78 79 /// Any further codegen related checks that need to be done on a function call 80 /// in a target specific manner. 81 virtual void checkFunctionCallABI(CodeGenModule &CGM, SourceLocation CallLoc, 82 const FunctionDecl *Caller, 83 const FunctionDecl *Callee, 84 const CallArgList &Args) const {} 85 86 /// Determines the size of struct _Unwind_Exception on this platform, 87 /// in 8-bit units. The Itanium ABI defines this as: 88 /// struct _Unwind_Exception { 89 /// uint64 exception_class; 90 /// _Unwind_Exception_Cleanup_Fn exception_cleanup; 91 /// uint64 private_1; 92 /// uint64 private_2; 93 /// }; 94 virtual unsigned getSizeOfUnwindException() const; 95 96 /// Controls whether __builtin_extend_pointer should sign-extend 97 /// pointers to uint64_t or zero-extend them (the default). Has 98 /// no effect for targets: 99 /// - that have 64-bit pointers, or 100 /// - that cannot address through registers larger than pointers, or 101 /// - that implicitly ignore/truncate the top bits when addressing 102 /// through such registers. 103 virtual bool extendPointerWithSExt() const { return false; } 104 105 /// Determines the DWARF register number for the stack pointer, for 106 /// exception-handling purposes. Implements __builtin_dwarf_sp_column. 107 /// 108 /// Returns -1 if the operation is unsupported by this target. 109 virtual int getDwarfEHStackPointer(CodeGen::CodeGenModule &M) const { 110 return -1; 111 } 112 113 /// Initializes the given DWARF EH register-size table, a char*. 114 /// Implements __builtin_init_dwarf_reg_size_table. 115 /// 116 /// Returns true if the operation is unsupported by this target. 117 virtual bool initDwarfEHRegSizeTable(CodeGen::CodeGenFunction &CGF, 118 llvm::Value *Address) const { 119 return true; 120 } 121 122 /// Performs the code-generation required to convert a return 123 /// address as stored by the system into the actual address of the 124 /// next instruction that will be executed. 125 /// 126 /// Used by __builtin_extract_return_addr(). 127 virtual llvm::Value *decodeReturnAddress(CodeGen::CodeGenFunction &CGF, 128 llvm::Value *Address) const { 129 return Address; 130 } 131 132 /// Performs the code-generation required to convert the address 133 /// of an instruction into a return address suitable for storage 134 /// by the system in a return slot. 135 /// 136 /// Used by __builtin_frob_return_addr(). 137 virtual llvm::Value *encodeReturnAddress(CodeGen::CodeGenFunction &CGF, 138 llvm::Value *Address) const { 139 return Address; 140 } 141 142 /// Performs a target specific test of a floating point value for things 143 /// like IsNaN, Infinity, ... Nullptr is returned if no implementation 144 /// exists. 145 virtual llvm::Value * 146 testFPKind(llvm::Value *V, unsigned BuiltinID, CGBuilderTy &Builder, 147 CodeGenModule &CGM) const { 148 assert(V->getType()->isFloatingPointTy() && "V should have an FP type."); 149 return nullptr; 150 } 151 152 /// Corrects the low-level LLVM type for a given constraint and "usual" 153 /// type. 154 /// 155 /// \returns A pointer to a new LLVM type, possibly the same as the original 156 /// on success; 0 on failure. 157 virtual llvm::Type *adjustInlineAsmType(CodeGen::CodeGenFunction &CGF, 158 StringRef Constraint, 159 llvm::Type *Ty) const { 160 return Ty; 161 } 162 163 /// Target hook to decide whether an inline asm operand can be passed 164 /// by value. 165 virtual bool isScalarizableAsmOperand(CodeGen::CodeGenFunction &CGF, 166 llvm::Type *Ty) const { 167 return false; 168 } 169 170 /// Adds constraints and types for result registers. 171 virtual void addReturnRegisterOutputs( 172 CodeGen::CodeGenFunction &CGF, CodeGen::LValue ReturnValue, 173 std::string &Constraints, std::vector<llvm::Type *> &ResultRegTypes, 174 std::vector<llvm::Type *> &ResultTruncRegTypes, 175 std::vector<CodeGen::LValue> &ResultRegDests, std::string &AsmString, 176 unsigned NumOutputs) const {} 177 178 /// doesReturnSlotInterfereWithArgs - Return true if the target uses an 179 /// argument slot for an 'sret' type. 180 virtual bool doesReturnSlotInterfereWithArgs() const { return true; } 181 182 /// Retrieve the address of a function to call immediately before 183 /// calling objc_retainAutoreleasedReturnValue. The 184 /// implementation of objc_autoreleaseReturnValue sniffs the 185 /// instruction stream following its return address to decide 186 /// whether it's a call to objc_retainAutoreleasedReturnValue. 187 /// This can be prohibitively expensive, depending on the 188 /// relocation model, and so on some targets it instead sniffs for 189 /// a particular instruction sequence. This functions returns 190 /// that instruction sequence in inline assembly, which will be 191 /// empty if none is required. 192 virtual StringRef getARCRetainAutoreleasedReturnValueMarker() const { 193 return ""; 194 } 195 196 /// Determine whether a call to objc_retainAutoreleasedReturnValue or 197 /// objc_unsafeClaimAutoreleasedReturnValue should be marked as 'notail'. 198 virtual bool markARCOptimizedReturnCallsAsNoTail() const { return false; } 199 200 /// Return a constant used by UBSan as a signature to identify functions 201 /// possessing type information, or 0 if the platform is unsupported. 202 virtual llvm::Constant * 203 getUBSanFunctionSignature(CodeGen::CodeGenModule &CGM) const { 204 return nullptr; 205 } 206 207 /// Determine whether a call to an unprototyped functions under 208 /// the given calling convention should use the variadic 209 /// convention or the non-variadic convention. 210 /// 211 /// There's a good reason to make a platform's variadic calling 212 /// convention be different from its non-variadic calling 213 /// convention: the non-variadic arguments can be passed in 214 /// registers (better for performance), and the variadic arguments 215 /// can be passed on the stack (also better for performance). If 216 /// this is done, however, unprototyped functions *must* use the 217 /// non-variadic convention, because C99 states that a call 218 /// through an unprototyped function type must succeed if the 219 /// function was defined with a non-variadic prototype with 220 /// compatible parameters. Therefore, splitting the conventions 221 /// makes it impossible to call a variadic function through an 222 /// unprototyped type. Since function prototypes came out in the 223 /// late 1970s, this is probably an acceptable trade-off. 224 /// Nonetheless, not all platforms are willing to make it, and in 225 /// particularly x86-64 bends over backwards to make the 226 /// conventions compatible. 227 /// 228 /// The default is false. This is correct whenever: 229 /// - the conventions are exactly the same, because it does not 230 /// matter and the resulting IR will be somewhat prettier in 231 /// certain cases; or 232 /// - the conventions are substantively different in how they pass 233 /// arguments, because in this case using the variadic convention 234 /// will lead to C99 violations. 235 /// 236 /// However, some platforms make the conventions identical except 237 /// for passing additional out-of-band information to a variadic 238 /// function: for example, x86-64 passes the number of SSE 239 /// arguments in %al. On these platforms, it is desirable to 240 /// call unprototyped functions using the variadic convention so 241 /// that unprototyped calls to varargs functions still succeed. 242 /// 243 /// Relatedly, platforms which pass the fixed arguments to this: 244 /// A foo(B, C, D); 245 /// differently than they would pass them to this: 246 /// A foo(B, C, D, ...); 247 /// may need to adjust the debugger-support code in Sema to do the 248 /// right thing when calling a function with no know signature. 249 virtual bool isNoProtoCallVariadic(const CodeGen::CallArgList &args, 250 const FunctionNoProtoType *fnType) const; 251 252 /// Gets the linker options necessary to link a dependent library on this 253 /// platform. 254 virtual void getDependentLibraryOption(llvm::StringRef Lib, 255 llvm::SmallString<24> &Opt) const; 256 257 /// Gets the linker options necessary to detect object file mismatches on 258 /// this platform. 259 virtual void getDetectMismatchOption(llvm::StringRef Name, 260 llvm::StringRef Value, 261 llvm::SmallString<32> &Opt) const {} 262 263 /// Get LLVM calling convention for OpenCL kernel. 264 virtual unsigned getOpenCLKernelCallingConv() const; 265 266 /// Get target specific null pointer. 267 /// \param T is the LLVM type of the null pointer. 268 /// \param QT is the clang QualType of the null pointer. 269 /// \return ConstantPointerNull with the given type \p T. 270 /// Each target can override it to return its own desired constant value. 271 virtual llvm::Constant *getNullPointer(const CodeGen::CodeGenModule &CGM, 272 llvm::PointerType *T, QualType QT) const; 273 274 /// Get target favored AST address space of a global variable for languages 275 /// other than OpenCL and CUDA. 276 /// If \p D is nullptr, returns the default target favored address space 277 /// for global variable. 278 virtual LangAS getGlobalVarAddressSpace(CodeGenModule &CGM, 279 const VarDecl *D) const; 280 281 /// Get the AST address space for alloca. 282 virtual LangAS getASTAllocaAddressSpace() const { return LangAS::Default; } 283 284 /// Perform address space cast of an expression of pointer type. 285 /// \param V is the LLVM value to be casted to another address space. 286 /// \param SrcAddr is the language address space of \p V. 287 /// \param DestAddr is the targeted language address space. 288 /// \param DestTy is the destination LLVM pointer type. 289 /// \param IsNonNull is the flag indicating \p V is known to be non null. 290 virtual llvm::Value *performAddrSpaceCast(CodeGen::CodeGenFunction &CGF, 291 llvm::Value *V, LangAS SrcAddr, 292 LangAS DestAddr, llvm::Type *DestTy, 293 bool IsNonNull = false) const; 294 295 /// Perform address space cast of a constant expression of pointer type. 296 /// \param V is the LLVM constant to be casted to another address space. 297 /// \param SrcAddr is the language address space of \p V. 298 /// \param DestAddr is the targeted language address space. 299 /// \param DestTy is the destination LLVM pointer type. 300 virtual llvm::Constant *performAddrSpaceCast(CodeGenModule &CGM, 301 llvm::Constant *V, 302 LangAS SrcAddr, LangAS DestAddr, 303 llvm::Type *DestTy) const; 304 305 /// Get address space of pointer parameter for __cxa_atexit. 306 virtual LangAS getAddrSpaceOfCxaAtexitPtrParam() const { 307 return LangAS::Default; 308 } 309 310 /// Get the syncscope used in LLVM IR. 311 virtual llvm::SyncScope::ID getLLVMSyncScopeID(const LangOptions &LangOpts, 312 SyncScope Scope, 313 llvm::AtomicOrdering Ordering, 314 llvm::LLVMContext &Ctx) const; 315 316 /// Interface class for filling custom fields of a block literal for OpenCL. 317 class TargetOpenCLBlockHelper { 318 public: 319 typedef std::pair<llvm::Value *, StringRef> ValueTy; 320 TargetOpenCLBlockHelper() {} 321 virtual ~TargetOpenCLBlockHelper() {} 322 /// Get the custom field types for OpenCL blocks. 323 virtual llvm::SmallVector<llvm::Type *, 1> getCustomFieldTypes() = 0; 324 /// Get the custom field values for OpenCL blocks. 325 virtual llvm::SmallVector<ValueTy, 1> 326 getCustomFieldValues(CodeGenFunction &CGF, const CGBlockInfo &Info) = 0; 327 virtual bool areAllCustomFieldValuesConstant(const CGBlockInfo &Info) = 0; 328 /// Get the custom field values for OpenCL blocks if all values are LLVM 329 /// constants. 330 virtual llvm::SmallVector<llvm::Constant *, 1> 331 getCustomFieldValues(CodeGenModule &CGM, const CGBlockInfo &Info) = 0; 332 }; 333 virtual TargetOpenCLBlockHelper *getTargetOpenCLBlockHelper() const { 334 return nullptr; 335 } 336 337 /// Create an OpenCL kernel for an enqueued block. The kernel function is 338 /// a wrapper for the block invoke function with target-specific calling 339 /// convention and ABI as an OpenCL kernel. The wrapper function accepts 340 /// block context and block arguments in target-specific way and calls 341 /// the original block invoke function. 342 virtual llvm::Function * 343 createEnqueuedBlockKernel(CodeGenFunction &CGF, 344 llvm::Function *BlockInvokeFunc, 345 llvm::Type *BlockTy) const; 346 347 /// \return true if the target supports alias from the unmangled name to the 348 /// mangled name of functions declared within an extern "C" region and marked 349 /// as 'used', and having internal linkage. 350 virtual bool shouldEmitStaticExternCAliases() const { return true; } 351 352 virtual void setCUDAKernelCallingConvention(const FunctionType *&FT) const {} 353 354 /// Return the device-side type for the CUDA device builtin surface type. 355 virtual llvm::Type *getCUDADeviceBuiltinSurfaceDeviceType() const { 356 // By default, no change from the original one. 357 return nullptr; 358 } 359 /// Return the device-side type for the CUDA device builtin texture type. 360 virtual llvm::Type *getCUDADeviceBuiltinTextureDeviceType() const { 361 // By default, no change from the original one. 362 return nullptr; 363 } 364 365 /// Emit the device-side copy of the builtin surface type. 366 virtual bool emitCUDADeviceBuiltinSurfaceDeviceCopy(CodeGenFunction &CGF, 367 LValue Dst, 368 LValue Src) const { 369 // DO NOTHING by default. 370 return false; 371 } 372 /// Emit the device-side copy of the builtin texture type. 373 virtual bool emitCUDADeviceBuiltinTextureDeviceCopy(CodeGenFunction &CGF, 374 LValue Dst, 375 LValue Src) const { 376 // DO NOTHING by default. 377 return false; 378 } 379 }; 380 381 } // namespace CodeGen 382 } // namespace clang 383 384 #endif // LLVM_CLANG_LIB_CODEGEN_TARGETINFO_H 385