216 lines
8.6 KiB
C++
216 lines
8.6 KiB
C++
//===---- TargetInfo.h - Encapsulate target details -------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// These classes wrap the information about a call or function
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// definition used to handle ABI compliancy.
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//
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//===----------------------------------------------------------------------===//
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#ifndef CLANG_CODEGEN_TARGETINFO_H
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#define CLANG_CODEGEN_TARGETINFO_H
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#include "clang/AST/Type.h"
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#include "clang/Basic/LLVM.h"
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#include "llvm/ADT/SmallString.h"
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#include "llvm/ADT/StringRef.h"
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namespace llvm {
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class Constant;
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class GlobalValue;
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class Type;
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class Value;
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}
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namespace clang {
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class ABIInfo;
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class Decl;
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namespace CodeGen {
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class CallArgList;
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class CodeGenModule;
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class CodeGenFunction;
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class CGFunctionInfo;
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}
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/// TargetCodeGenInfo - This class organizes various target-specific
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/// codegeneration issues, like target-specific attributes, builtins and so
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/// on.
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class TargetCodeGenInfo {
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ABIInfo *Info;
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public:
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// WARNING: Acquires the ownership of ABIInfo.
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TargetCodeGenInfo(ABIInfo *info = 0) : Info(info) {}
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virtual ~TargetCodeGenInfo();
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/// getABIInfo() - Returns ABI info helper for the target.
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const ABIInfo &getABIInfo() const { return *Info; }
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/// SetTargetAttributes - Provides a convenient hook to handle extra
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/// target-specific attributes for the given global.
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virtual void SetTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
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CodeGen::CodeGenModule &M) const {}
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/// EmitTargetMD - Provides a convenient hook to handle extra
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/// target-specific metadata for the given global.
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virtual void emitTargetMD(const Decl *D, llvm::GlobalValue *GV,
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CodeGen::CodeGenModule &M) const {}
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/// Determines the size of struct _Unwind_Exception on this platform,
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/// in 8-bit units. The Itanium ABI defines this as:
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/// struct _Unwind_Exception {
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/// uint64 exception_class;
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/// _Unwind_Exception_Cleanup_Fn exception_cleanup;
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/// uint64 private_1;
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/// uint64 private_2;
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/// };
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virtual unsigned getSizeOfUnwindException() const;
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/// Controls whether __builtin_extend_pointer should sign-extend
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/// pointers to uint64_t or zero-extend them (the default). Has
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/// no effect for targets:
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/// - that have 64-bit pointers, or
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/// - that cannot address through registers larger than pointers, or
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/// - that implicitly ignore/truncate the top bits when addressing
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/// through such registers.
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virtual bool extendPointerWithSExt() const { return false; }
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/// Determines the DWARF register number for the stack pointer, for
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/// exception-handling purposes. Implements __builtin_dwarf_sp_column.
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///
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/// Returns -1 if the operation is unsupported by this target.
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virtual int getDwarfEHStackPointer(CodeGen::CodeGenModule &M) const {
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return -1;
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}
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/// Initializes the given DWARF EH register-size table, a char*.
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/// Implements __builtin_init_dwarf_reg_size_table.
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///
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/// Returns true if the operation is unsupported by this target.
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virtual bool initDwarfEHRegSizeTable(CodeGen::CodeGenFunction &CGF,
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llvm::Value *Address) const {
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return true;
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}
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/// Performs the code-generation required to convert a return
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/// address as stored by the system into the actual address of the
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/// next instruction that will be executed.
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///
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/// Used by __builtin_extract_return_addr().
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virtual llvm::Value *decodeReturnAddress(CodeGen::CodeGenFunction &CGF,
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llvm::Value *Address) const {
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return Address;
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}
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/// Performs the code-generation required to convert the address
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/// of an instruction into a return address suitable for storage
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/// by the system in a return slot.
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///
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/// Used by __builtin_frob_return_addr().
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virtual llvm::Value *encodeReturnAddress(CodeGen::CodeGenFunction &CGF,
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llvm::Value *Address) const {
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return Address;
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}
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/// Corrects the low-level LLVM type for a given constraint and "usual"
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/// type.
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///
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/// \returns A pointer to a new LLVM type, possibly the same as the original
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/// on success; 0 on failure.
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virtual llvm::Type *adjustInlineAsmType(CodeGen::CodeGenFunction &CGF,
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StringRef Constraint,
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llvm::Type *Ty) const {
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return Ty;
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}
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/// doesReturnSlotInterfereWithArgs - Return true if the target uses an
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/// argument slot for an 'sret' type.
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virtual bool doesReturnSlotInterfereWithArgs() const { return true; }
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/// Retrieve the address of a function to call immediately before
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/// calling objc_retainAutoreleasedReturnValue. The
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/// implementation of objc_autoreleaseReturnValue sniffs the
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/// instruction stream following its return address to decide
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/// whether it's a call to objc_retainAutoreleasedReturnValue.
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/// This can be prohibitively expensive, depending on the
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/// relocation model, and so on some targets it instead sniffs for
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/// a particular instruction sequence. This functions returns
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/// that instruction sequence in inline assembly, which will be
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/// empty if none is required.
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virtual StringRef getARCRetainAutoreleasedReturnValueMarker() const {
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return "";
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}
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/// Return a constant used by UBSan as a signature to identify functions
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/// possessing type information, or 0 if the platform is unsupported.
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virtual llvm::Constant *
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getUBSanFunctionSignature(CodeGen::CodeGenModule &CGM) const {
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return nullptr;
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}
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/// Determine whether a call to an unprototyped functions under
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/// the given calling convention should use the variadic
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/// convention or the non-variadic convention.
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///
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/// There's a good reason to make a platform's variadic calling
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/// convention be different from its non-variadic calling
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/// convention: the non-variadic arguments can be passed in
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/// registers (better for performance), and the variadic arguments
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/// can be passed on the stack (also better for performance). If
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/// this is done, however, unprototyped functions *must* use the
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/// non-variadic convention, because C99 states that a call
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/// through an unprototyped function type must succeed if the
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/// function was defined with a non-variadic prototype with
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/// compatible parameters. Therefore, splitting the conventions
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/// makes it impossible to call a variadic function through an
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/// unprototyped type. Since function prototypes came out in the
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/// late 1970s, this is probably an acceptable trade-off.
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/// Nonetheless, not all platforms are willing to make it, and in
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/// particularly x86-64 bends over backwards to make the
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/// conventions compatible.
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///
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/// The default is false. This is correct whenever:
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/// - the conventions are exactly the same, because it does not
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/// matter and the resulting IR will be somewhat prettier in
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/// certain cases; or
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/// - the conventions are substantively different in how they pass
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/// arguments, because in this case using the variadic convention
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/// will lead to C99 violations.
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///
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/// However, some platforms make the conventions identical except
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/// for passing additional out-of-band information to a variadic
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/// function: for example, x86-64 passes the number of SSE
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/// arguments in %al. On these platforms, it is desirable to
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/// call unprototyped functions using the variadic convention so
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/// that unprototyped calls to varargs functions still succeed.
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///
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/// Relatedly, platforms which pass the fixed arguments to this:
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/// A foo(B, C, D);
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/// differently than they would pass them to this:
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/// A foo(B, C, D, ...);
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/// may need to adjust the debugger-support code in Sema to do the
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/// right thing when calling a function with no know signature.
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virtual bool isNoProtoCallVariadic(const CodeGen::CallArgList &args,
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const FunctionNoProtoType *fnType) const;
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/// Gets the linker options necessary to link a dependent library on this
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/// platform.
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virtual void getDependentLibraryOption(llvm::StringRef Lib,
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llvm::SmallString<24> &Opt) const;
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/// Gets the linker options necessary to detect object file mismatches on
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/// this platform.
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virtual void getDetectMismatchOption(llvm::StringRef Name,
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llvm::StringRef Value,
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llvm::SmallString<32> &Opt) const {}
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};
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}
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#endif // CLANG_CODEGEN_TARGETINFO_H
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