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