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
25namespace llvm {
26class Constant;
27class GlobalValue;
28class Type;
29class Value;
30}
31
32namespace clang {
33class Decl;
34
35namespace CodeGen {
36class ABIInfo;
37class CallArgList;
38class CodeGenFunction;
39class CGBlockInfo;
40class CGFunctionInfo;
41
42/// TargetCodeGenInfo - This class organizes various target-specific
43/// codegeneration issues, like target-specific attributes, builtins and so
44/// on.
45class TargetCodeGenInfo {
46  std::unique_ptr<ABIInfo> Info = nullptr;
47
48public:
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 should be
167  /// marked as 'notail'.
168  virtual bool shouldSuppressTailCallsOfRetainAutoreleasedReturnValue() const {
169    return false;
170  }
171
172  /// Return a constant used by UBSan as a signature to identify functions
173  /// possessing type information, or 0 if the platform is unsupported.
174  virtual llvm::Constant *
175  getUBSanFunctionSignature(CodeGen::CodeGenModule &CGM) const {
176    return nullptr;
177  }
178
179  /// Determine whether a call to an unprototyped functions under
180  /// the given calling convention should use the variadic
181  /// convention or the non-variadic convention.
182  ///
183  /// There's a good reason to make a platform's variadic calling
184  /// convention be different from its non-variadic calling
185  /// convention: the non-variadic arguments can be passed in
186  /// registers (better for performance), and the variadic arguments
187  /// can be passed on the stack (also better for performance).  If
188  /// this is done, however, unprototyped functions *must* use the
189  /// non-variadic convention, because C99 states that a call
190  /// through an unprototyped function type must succeed if the
191  /// function was defined with a non-variadic prototype with
192  /// compatible parameters.  Therefore, splitting the conventions
193  /// makes it impossible to call a variadic function through an
194  /// unprototyped type.  Since function prototypes came out in the
195  /// late 1970s, this is probably an acceptable trade-off.
196  /// Nonetheless, not all platforms are willing to make it, and in
197  /// particularly x86-64 bends over backwards to make the
198  /// conventions compatible.
199  ///
200  /// The default is false.  This is correct whenever:
201  ///   - the conventions are exactly the same, because it does not
202  ///     matter and the resulting IR will be somewhat prettier in
203  ///     certain cases; or
204  ///   - the conventions are substantively different in how they pass
205  ///     arguments, because in this case using the variadic convention
206  ///     will lead to C99 violations.
207  ///
208  /// However, some platforms make the conventions identical except
209  /// for passing additional out-of-band information to a variadic
210  /// function: for example, x86-64 passes the number of SSE
211  /// arguments in %al.  On these platforms, it is desirable to
212  /// call unprototyped functions using the variadic convention so
213  /// that unprototyped calls to varargs functions still succeed.
214  ///
215  /// Relatedly, platforms which pass the fixed arguments to this:
216  ///   A foo(B, C, D);
217  /// differently than they would pass them to this:
218  ///   A foo(B, C, D, ...);
219  /// may need to adjust the debugger-support code in Sema to do the
220  /// right thing when calling a function with no know signature.
221  virtual bool isNoProtoCallVariadic(const CodeGen::CallArgList &args,
222                                     const FunctionNoProtoType *fnType) const;
223
224  /// Gets the linker options necessary to link a dependent library on this
225  /// platform.
226  virtual void getDependentLibraryOption(llvm::StringRef Lib,
227                                         llvm::SmallString<24> &Opt) const;
228
229  /// Gets the linker options necessary to detect object file mismatches on
230  /// this platform.
231  virtual void getDetectMismatchOption(llvm::StringRef Name,
232                                       llvm::StringRef Value,
233                                       llvm::SmallString<32> &Opt) const {}
234
235  /// Get LLVM calling convention for OpenCL kernel.
236  virtual unsigned getOpenCLKernelCallingConv() const;
237
238  /// Get target specific null pointer.
239  /// \param T is the LLVM type of the null pointer.
240  /// \param QT is the clang QualType of the null pointer.
241  /// \return ConstantPointerNull with the given type \p T.
242  /// Each target can override it to return its own desired constant value.
243  virtual llvm::Constant *getNullPointer(const CodeGen::CodeGenModule &CGM,
244      llvm::PointerType *T, QualType QT) const;
245
246  /// Get target favored AST address space of a global variable for languages
247  /// other than OpenCL and CUDA.
248  /// If \p D is nullptr, returns the default target favored address space
249  /// for global variable.
250  virtual LangAS getGlobalVarAddressSpace(CodeGenModule &CGM,
251                                          const VarDecl *D) const;
252
253  /// Get the AST address space for alloca.
254  virtual LangAS getASTAllocaAddressSpace() const { return LangAS::Default; }
255
256  /// Perform address space cast of an expression of pointer type.
257  /// \param V is the LLVM value to be casted to another address space.
258  /// \param SrcAddr is the language address space of \p V.
259  /// \param DestAddr is the targeted language address space.
260  /// \param DestTy is the destination LLVM pointer type.
261  /// \param IsNonNull is the flag indicating \p V is known to be non null.
262  virtual llvm::Value *performAddrSpaceCast(CodeGen::CodeGenFunction &CGF,
263                                            llvm::Value *V, LangAS SrcAddr,
264                                            LangAS DestAddr, llvm::Type *DestTy,
265                                            bool IsNonNull = false) const;
266
267  /// Perform address space cast of a constant expression of pointer type.
268  /// \param V is the LLVM constant to be casted to another address space.
269  /// \param SrcAddr is the language address space of \p V.
270  /// \param DestAddr is the targeted language address space.
271  /// \param DestTy is the destination LLVM pointer type.
272  virtual llvm::Constant *performAddrSpaceCast(CodeGenModule &CGM,
273                                               llvm::Constant *V,
274                                               LangAS SrcAddr, LangAS DestAddr,
275                                               llvm::Type *DestTy) const;
276
277  /// Get address space of pointer parameter for __cxa_atexit.
278  virtual LangAS getAddrSpaceOfCxaAtexitPtrParam() const {
279    return LangAS::Default;
280  }
281
282  /// Get the syncscope used in LLVM IR.
283  virtual llvm::SyncScope::ID getLLVMSyncScopeID(const LangOptions &LangOpts,
284                                                 SyncScope Scope,
285                                                 llvm::AtomicOrdering Ordering,
286                                                 llvm::LLVMContext &Ctx) const;
287
288  /// Interface class for filling custom fields of a block literal for OpenCL.
289  class TargetOpenCLBlockHelper {
290  public:
291    typedef std::pair<llvm::Value *, StringRef> ValueTy;
292    TargetOpenCLBlockHelper() {}
293    virtual ~TargetOpenCLBlockHelper() {}
294    /// Get the custom field types for OpenCL blocks.
295    virtual llvm::SmallVector<llvm::Type *, 1> getCustomFieldTypes() = 0;
296    /// Get the custom field values for OpenCL blocks.
297    virtual llvm::SmallVector<ValueTy, 1>
298    getCustomFieldValues(CodeGenFunction &CGF, const CGBlockInfo &Info) = 0;
299    virtual bool areAllCustomFieldValuesConstant(const CGBlockInfo &Info) = 0;
300    /// Get the custom field values for OpenCL blocks if all values are LLVM
301    /// constants.
302    virtual llvm::SmallVector<llvm::Constant *, 1>
303    getCustomFieldValues(CodeGenModule &CGM, const CGBlockInfo &Info) = 0;
304  };
305  virtual TargetOpenCLBlockHelper *getTargetOpenCLBlockHelper() const {
306    return nullptr;
307  }
308
309  /// Create an OpenCL kernel for an enqueued block. The kernel function is
310  /// a wrapper for the block invoke function with target-specific calling
311  /// convention and ABI as an OpenCL kernel. The wrapper function accepts
312  /// block context and block arguments in target-specific way and calls
313  /// the original block invoke function.
314  virtual llvm::Function *
315  createEnqueuedBlockKernel(CodeGenFunction &CGF,
316                            llvm::Function *BlockInvokeFunc,
317                            llvm::Value *BlockLiteral) const;
318
319  /// \return true if the target supports alias from the unmangled name to the
320  /// mangled name of functions declared within an extern "C" region and marked
321  /// as 'used', and having internal linkage.
322  virtual bool shouldEmitStaticExternCAliases() const { return true; }
323
324  virtual void setCUDAKernelCallingConvention(const FunctionType *&FT) const {}
325
326  /// Return the device-side type for the CUDA device builtin surface type.
327  virtual llvm::Type *getCUDADeviceBuiltinSurfaceDeviceType() const {
328    // By default, no change from the original one.
329    return nullptr;
330  }
331  /// Return the device-side type for the CUDA device builtin texture type.
332  virtual llvm::Type *getCUDADeviceBuiltinTextureDeviceType() const {
333    // By default, no change from the original one.
334    return nullptr;
335  }
336
337  /// Emit the device-side copy of the builtin surface type.
338  virtual bool emitCUDADeviceBuiltinSurfaceDeviceCopy(CodeGenFunction &CGF,
339                                                      LValue Dst,
340                                                      LValue Src) const {
341    // DO NOTHING by default.
342    return false;
343  }
344  /// Emit the device-side copy of the builtin texture type.
345  virtual bool emitCUDADeviceBuiltinTextureDeviceCopy(CodeGenFunction &CGF,
346                                                      LValue Dst,
347                                                      LValue Src) const {
348    // DO NOTHING by default.
349    return false;
350  }
351};
352
353} // namespace CodeGen
354} // namespace clang
355
356#endif // LLVM_CLANG_LIB_CODEGEN_TARGETINFO_H
357