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