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//===---- TargetInfo.h - Encapsulate target details -------------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// These classes wrap the information about a call or function
// definition used to handle ABI compliancy.
#include "CodeGenModule.h"
#include "CGValue.h"
#include "clang/AST/Type.h"
#include "clang/Basic/LLVM.h"
#include "clang/Basic/SyncScope.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringRef.h"
namespace llvm {
class Constant;
class GlobalValue;
class Type;
class Value;
namespace clang {
class Decl;
namespace CodeGen {
class ABIInfo;
class CallArgList;
class CodeGenFunction;
class CGBlockInfo;
class CGFunctionInfo;
/// TargetCodeGenInfo - This class organizes various target-specific
/// codegeneration issues, like target-specific attributes, builtins and so
/// on.
class TargetCodeGenInfo {
ABIInfo *Info;
// WARNING: Acquires the ownership of ABIInfo.
TargetCodeGenInfo(ABIInfo *info = nullptr) : Info(info) {}
virtual ~TargetCodeGenInfo();
/// getABIInfo() - Returns ABI info helper for the target.
const ABIInfo &getABIInfo() const { return *Info; }
/// setTargetAttributes - Provides a convenient hook to handle extra
/// target-specific attributes for the given global.
virtual void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
CodeGen::CodeGenModule &M) const {}
/// emitTargetMD - Provides a convenient hook to handle extra
/// target-specific metadata for the given global.
virtual void emitTargetMD(const Decl *D, llvm::GlobalValue *GV,
CodeGen::CodeGenModule &M) const {}
/// Determines the size of struct _Unwind_Exception on this platform,
/// in 8-bit units. The Itanium ABI defines this as:
/// struct _Unwind_Exception {
/// uint64 exception_class;
/// _Unwind_Exception_Cleanup_Fn exception_cleanup;
/// uint64 private_1;
/// uint64 private_2;
/// };
virtual unsigned getSizeOfUnwindException() const;
/// Controls whether __builtin_extend_pointer should sign-extend
/// pointers to uint64_t or zero-extend them (the default). Has
/// no effect for targets:
/// - that have 64-bit pointers, or
/// - that cannot address through registers larger than pointers, or
/// - that implicitly ignore/truncate the top bits when addressing
/// through such registers.
virtual bool extendPointerWithSExt() const { return false; }
/// Determines the DWARF register number for the stack pointer, for
/// exception-handling purposes. Implements __builtin_dwarf_sp_column.
/// Returns -1 if the operation is unsupported by this target.
virtual int getDwarfEHStackPointer(CodeGen::CodeGenModule &M) const {
return -1;
/// Initializes the given DWARF EH register-size table, a char*.
/// Implements __builtin_init_dwarf_reg_size_table.
/// Returns true if the operation is unsupported by this target.
virtual bool initDwarfEHRegSizeTable(CodeGen::CodeGenFunction &CGF,
llvm::Value *Address) const {
return true;
/// Performs the code-generation required to convert a return
/// address as stored by the system into the actual address of the
/// next instruction that will be executed.
/// Used by __builtin_extract_return_addr().
virtual llvm::Value *decodeReturnAddress(CodeGen::CodeGenFunction &CGF,
llvm::Value *Address) const {
return Address;
/// Performs the code-generation required to convert the address
/// of an instruction into a return address suitable for storage
/// by the system in a return slot.
/// Used by __builtin_frob_return_addr().
virtual llvm::Value *encodeReturnAddress(CodeGen::CodeGenFunction &CGF,
llvm::Value *Address) const {
return Address;
/// Corrects the low-level LLVM type for a given constraint and "usual"
/// type.
/// \returns A pointer to a new LLVM type, possibly the same as the original
/// on success; 0 on failure.
virtual llvm::Type *adjustInlineAsmType(CodeGen::CodeGenFunction &CGF,
StringRef Constraint,
llvm::Type *Ty) const {
return Ty;
/// Adds constraints and types for result registers.
virtual void addReturnRegisterOutputs(
CodeGen::CodeGenFunction &CGF, CodeGen::LValue ReturnValue,
std::string &Constraints, std::vector<llvm::Type *> &ResultRegTypes,
std::vector<llvm::Type *> &ResultTruncRegTypes,
std::vector<CodeGen::LValue> &ResultRegDests, std::string &AsmString,
unsigned NumOutputs) const {}
/// doesReturnSlotInterfereWithArgs - Return true if the target uses an
/// argument slot for an 'sret' type.
virtual bool doesReturnSlotInterfereWithArgs() const { return true; }
/// Retrieve the address of a function to call immediately before
/// calling objc_retainAutoreleasedReturnValue. The
/// implementation of objc_autoreleaseReturnValue sniffs the
/// instruction stream following its return address to decide
/// whether it's a call to objc_retainAutoreleasedReturnValue.
/// This can be prohibitively expensive, depending on the
/// relocation model, and so on some targets it instead sniffs for
/// a particular instruction sequence. This functions returns
/// that instruction sequence in inline assembly, which will be
/// empty if none is required.
virtual StringRef getARCRetainAutoreleasedReturnValueMarker() const {
return "";
/// Determine whether a call to objc_retainAutoreleasedReturnValue should be
/// marked as 'notail'.
virtual bool shouldSuppressTailCallsOfRetainAutoreleasedReturnValue() const {
return false;
/// Return a constant used by UBSan as a signature to identify functions
/// possessing type information, or 0 if the platform is unsupported.
virtual llvm::Constant *
getUBSanFunctionSignature(CodeGen::CodeGenModule &CGM) const {
return nullptr;
/// Determine whether a call to an unprototyped functions under
/// the given calling convention should use the variadic
/// convention or the non-variadic convention.
/// There's a good reason to make a platform's variadic calling
/// convention be different from its non-variadic calling
/// convention: the non-variadic arguments can be passed in
/// registers (better for performance), and the variadic arguments
/// can be passed on the stack (also better for performance). If
/// this is done, however, unprototyped functions *must* use the
/// non-variadic convention, because C99 states that a call
/// through an unprototyped function type must succeed if the
/// function was defined with a non-variadic prototype with
/// compatible parameters. Therefore, splitting the conventions
/// makes it impossible to call a variadic function through an
/// unprototyped type. Since function prototypes came out in the
/// late 1970s, this is probably an acceptable trade-off.
/// Nonetheless, not all platforms are willing to make it, and in
/// particularly x86-64 bends over backwards to make the
/// conventions compatible.
/// The default is false. This is correct whenever:
/// - the conventions are exactly the same, because it does not
/// matter and the resulting IR will be somewhat prettier in
/// certain cases; or
/// - the conventions are substantively different in how they pass
/// arguments, because in this case using the variadic convention
/// will lead to C99 violations.
/// However, some platforms make the conventions identical except
/// for passing additional out-of-band information to a variadic
/// function: for example, x86-64 passes the number of SSE
/// arguments in %al. On these platforms, it is desirable to
/// call unprototyped functions using the variadic convention so
/// that unprototyped calls to varargs functions still succeed.
/// Relatedly, platforms which pass the fixed arguments to this:
/// A foo(B, C, D);
/// differently than they would pass them to this:
/// A foo(B, C, D, ...);
/// may need to adjust the debugger-support code in Sema to do the
/// right thing when calling a function with no know signature.
virtual bool isNoProtoCallVariadic(const CodeGen::CallArgList &args,
const FunctionNoProtoType *fnType) const;
/// Gets the linker options necessary to link a dependent library on this
/// platform.
virtual void getDependentLibraryOption(llvm::StringRef Lib,
llvm::SmallString<24> &Opt) const;
/// Gets the linker options necessary to detect object file mismatches on
/// this platform.
virtual void getDetectMismatchOption(llvm::StringRef Name,
llvm::StringRef Value,
llvm::SmallString<32> &Opt) const {}
/// Get LLVM calling convention for OpenCL kernel.
virtual unsigned getOpenCLKernelCallingConv() const;
/// Get target specific null pointer.
/// \param T is the LLVM type of the null pointer.
/// \param QT is the clang QualType of the null pointer.
/// \return ConstantPointerNull with the given type \p T.
/// Each target can override it to return its own desired constant value.
virtual llvm::Constant *getNullPointer(const CodeGen::CodeGenModule &CGM,
llvm::PointerType *T, QualType QT) const;
/// Get target favored AST address space of a global variable for languages
/// other than OpenCL and CUDA.
/// If \p D is nullptr, returns the default target favored address space
/// for global variable.
virtual LangAS getGlobalVarAddressSpace(CodeGenModule &CGM,
const VarDecl *D) const;
/// Get the AST address space for alloca.
virtual LangAS getASTAllocaAddressSpace() const { return LangAS::Default; }
/// Perform address space cast of an expression of pointer type.
/// \param V is the LLVM value to be casted to another address space.
/// \param SrcAddr is the language address space of \p V.
/// \param DestAddr is the targeted language address space.
/// \param DestTy is the destination LLVM pointer type.
/// \param IsNonNull is the flag indicating \p V is known to be non null.
virtual llvm::Value *performAddrSpaceCast(CodeGen::CodeGenFunction &CGF,
llvm::Value *V, LangAS SrcAddr,
LangAS DestAddr, llvm::Type *DestTy,
bool IsNonNull = false) const;
/// Perform address space cast of a constant expression of pointer type.
/// \param V is the LLVM constant to be casted to another address space.
/// \param SrcAddr is the language address space of \p V.
/// \param DestAddr is the targeted language address space.
/// \param DestTy is the destination LLVM pointer type.
virtual llvm::Constant *performAddrSpaceCast(CodeGenModule &CGM,
llvm::Constant *V,
LangAS SrcAddr, LangAS DestAddr,
llvm::Type *DestTy) const;
/// Get address space of pointer parameter for __cxa_atexit.
virtual LangAS getAddrSpaceOfCxaAtexitPtrParam() const {
return LangAS::Default;
/// Get the syncscope used in LLVM IR.
virtual llvm::SyncScope::ID getLLVMSyncScopeID(const LangOptions &LangOpts,
SyncScope Scope,
llvm::AtomicOrdering Ordering,
llvm::LLVMContext &Ctx) const;
/// Interface class for filling custom fields of a block literal for OpenCL.
class TargetOpenCLBlockHelper {
typedef std::pair<llvm::Value *, StringRef> ValueTy;
TargetOpenCLBlockHelper() {}
virtual ~TargetOpenCLBlockHelper() {}
/// Get the custom field types for OpenCL blocks.
virtual llvm::SmallVector<llvm::Type *, 1> getCustomFieldTypes() = 0;
/// Get the custom field values for OpenCL blocks.
virtual llvm::SmallVector<ValueTy, 1>
getCustomFieldValues(CodeGenFunction &CGF, const CGBlockInfo &Info) = 0;
virtual bool areAllCustomFieldValuesConstant(const CGBlockInfo &Info) = 0;
/// Get the custom field values for OpenCL blocks if all values are LLVM
/// constants.
virtual llvm::SmallVector<llvm::Constant *, 1>
getCustomFieldValues(CodeGenModule &CGM, const CGBlockInfo &Info) = 0;
virtual TargetOpenCLBlockHelper *getTargetOpenCLBlockHelper() const {
return nullptr;
/// Create an OpenCL kernel for an enqueued block. The kernel function is
/// a wrapper for the block invoke function with target-specific calling
/// convention and ABI as an OpenCL kernel. The wrapper function accepts
/// block context and block arguments in target-specific way and calls
/// the original block invoke function.
virtual llvm::Function *
createEnqueuedBlockKernel(CodeGenFunction &CGF,
llvm::Function *BlockInvokeFunc,
llvm::Value *BlockLiteral) const;
/// \return true if the target supports alias from the unmangled name to the
/// mangled name of functions declared within an extern "C" region and marked
/// as 'used', and having internal linkage.
virtual bool shouldEmitStaticExternCAliases() const { return true; }
virtual void setCUDAKernelCallingConvention(const FunctionType *&FT) const {}
} // namespace CodeGen
} // namespace clang