1 //===---- TargetInfo.h - Encapsulate target details -------------*- C++ -*-===//
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
7 //===----------------------------------------------------------------------===//
9 // These classes wrap the information about a call or function
10 // definition used to handle ABI compliancy.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CLANG_LIB_CODEGEN_TARGETINFO_H
15 #define LLVM_CLANG_LIB_CODEGEN_TARGETINFO_H
17 #include "CodeGenModule.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"
38 class CodeGenFunction;
42 /// TargetCodeGenInfo - This class organizes various target-specific
43 /// codegeneration issues, like target-specific attributes, builtins and so
45 class TargetCodeGenInfo {
49 // WARNING: Acquires the ownership of ABIInfo.
50 TargetCodeGenInfo(ABIInfo *info = nullptr) : Info(info) {}
51 virtual ~TargetCodeGenInfo();
53 /// getABIInfo() - Returns ABI info helper for the target.
54 const ABIInfo &getABIInfo() const { return *Info; }
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 {}
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 {}
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;
74 virtual unsigned getSizeOfUnwindException() const;
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; }
85 /// Determines the DWARF register number for the stack pointer, for
86 /// exception-handling purposes. Implements __builtin_dwarf_sp_column.
88 /// Returns -1 if the operation is unsupported by this target.
89 virtual int getDwarfEHStackPointer(CodeGen::CodeGenModule &M) const {
93 /// Initializes the given DWARF EH register-size table, a char*.
94 /// Implements __builtin_init_dwarf_reg_size_table.
96 /// Returns true if the operation is unsupported by this target.
97 virtual bool initDwarfEHRegSizeTable(CodeGen::CodeGenFunction &CGF,
98 llvm::Value *Address) const {
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.
106 /// Used by __builtin_extract_return_addr().
107 virtual llvm::Value *decodeReturnAddress(CodeGen::CodeGenFunction &CGF,
108 llvm::Value *Address) const {
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.
116 /// Used by __builtin_frob_return_addr().
117 virtual llvm::Value *encodeReturnAddress(CodeGen::CodeGenFunction &CGF,
118 llvm::Value *Address) const {
122 /// Corrects the low-level LLVM type for a given constraint and "usual"
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 {
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 {}
141 /// doesReturnSlotInterfereWithArgs - Return true if the target uses an
142 /// argument slot for an 'sret' type.
143 virtual bool doesReturnSlotInterfereWithArgs() const { return true; }
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 {
159 /// Determine whether a call to objc_retainAutoreleasedReturnValue should be
160 /// marked as 'notail'.
161 virtual bool shouldSuppressTailCallsOfRetainAutoreleasedReturnValue() const {
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 {
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.
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.
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.
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.
208 /// Relatedly, platforms which pass the fixed arguments to this:
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;
217 /// Gets the linker options necessary to link a dependent library on this
219 virtual void getDependentLibraryOption(llvm::StringRef Lib,
220 llvm::SmallString<24> &Opt) const;
222 /// Gets the linker options necessary to detect object file mismatches on
224 virtual void getDetectMismatchOption(llvm::StringRef Name,
225 llvm::StringRef Value,
226 llvm::SmallString<32> &Opt) const {}
228 /// Get LLVM calling convention for OpenCL kernel.
229 virtual unsigned getOpenCLKernelCallingConv() const;
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;
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;
246 /// Get the AST address space for alloca.
247 virtual LangAS getASTAllocaAddressSpace() const { return LangAS::Default; }
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;
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,
267 LangAS SrcAddr, LangAS DestAddr,
268 llvm::Type *DestTy) const;
270 /// Get address space of pointer parameter for __cxa_atexit.
271 virtual LangAS getAddrSpaceOfCxaAtexitPtrParam() const {
272 return LangAS::Default;
275 /// Get the syncscope used in LLVM IR.
276 virtual llvm::SyncScope::ID getLLVMSyncScopeID(const LangOptions &LangOpts,
278 llvm::AtomicOrdering Ordering,
279 llvm::LLVMContext &Ctx) const;
281 /// Interface class for filling custom fields of a block literal for OpenCL.
282 class TargetOpenCLBlockHelper {
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
295 virtual llvm::SmallVector<llvm::Constant *, 1>
296 getCustomFieldValues(CodeGenModule &CGM, const CGBlockInfo &Info) = 0;
298 virtual TargetOpenCLBlockHelper *getTargetOpenCLBlockHelper() const {
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;
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; }
317 virtual void setCUDAKernelCallingConvention(const FunctionType *&FT) const {}
320 } // namespace CodeGen
323 #endif // LLVM_CLANG_LIB_CODEGEN_TARGETINFO_H