TargetInfo.h

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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 https://llvm.org/LICENSE.txt 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.
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_CLANG_LIB_CIR_TARGETINFO_H
#define LLVM_CLANG_LIB_CIR_TARGETINFO_H
 
#include "ABIInfo.h"
#include "CIRGenTypes.h"
#include "mlir/Dialect/Ptr/IR/MemorySpaceInterfaces.h"
#include "clang/Basic/AddressSpaces.h"
#include "clang/CIR/Dialect/IR/CIRAttrs.h"
#include "clang/CIR/Dialect/IR/CIRDialect.h"
#include "clang/CIR/Dialect/IR/CIROpsEnums.h"
 
#include <memory>
#include <utility>
 
namespace clang::CIRGen {
 
/// isEmptyFieldForLayout - Return true if the field is "empty", that is,
/// either a zero-width bit-field or an isEmptyRecordForLayout.
bool isEmptyFieldForLayout(const ASTContext &context, const FieldDecl *fd);
 
/// isEmptyRecordForLayout - Return true if a structure contains only empty
/// base classes (per  isEmptyRecordForLayout) and fields (per
/// isEmptyFieldForLayout). Note, C++ record fields are considered empty
/// if the [[no_unique_address]] attribute would have made them empty.
bool isEmptyRecordForLayout(const ASTContext &context, QualType t);
 
/// isEmptyFieldForABI - Return true if the field is "empty", that is, it is an
/// unnamed bit-field or an (array of) empty record(s).  C++ record fields are
/// never empty unless marked [[no_unique_address]], and that exception applies
/// only to records, not arrays of records.
bool isEmptyFieldForABI(const ASTContext &context, const FieldDecl *fd);
 
/// isEmptyRecordForABI - Return true if a structure contains only empty base
/// classes and fields.  Note that a structure with a flexible array member is
/// not considered empty, and neither is a polymorphic class, whose vtable
/// pointer is neither a base nor a field.
bool isEmptyRecordForABI(const ASTContext &context, QualType t);
 
class CIRGenFunction;
 
class TargetCIRGenInfo {
  std::unique_ptr<ABIInfo> info;
 
public:
  TargetCIRGenInfo(std::unique_ptr<ABIInfo> info) : info(std::move(info)) {}
 
  virtual ~TargetCIRGenInfo() = default;
 
  /// Returns ABI info helper for the target.
  const ABIInfo &getABIInfo() const { return *info; }
 
  /// Returns true if the target supports math library calls.
  virtual bool supportsLibCall() const { return true; }
 
  /// 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 clang::LangAS getGlobalVarAddressSpace(CIRGenModule &cgm,
                                                 const clang::VarDecl *d) const;
 
  /// Get the address space for alloca.
  virtual mlir::ptr::MemorySpaceAttrInterface getCIRAllocaAddressSpace() const {
    return cir::LangAddressSpaceAttr::get(&info->cgt.getMLIRContext(),
                                          cir::LangAddressSpace::Default);
  }
 
  virtual mlir::Type getCUDADeviceBuiltinSurfaceDeviceType() 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 FunctionNoProtoType *fnType) const;
 
  /// Returns true if inlining the function call would produce incorrect code
  /// for the current target and should be ignored (even with the always_inline
  /// or flatten attributes).
  ///
  /// Note: This probably should be handled in LLVM. However, the LLVM
  /// `alwaysinline` attribute currently means the inliner will ignore
  /// mismatched attributes (which sometimes can generate invalid code). So,
  /// this hook allows targets to avoid adding the LLVM `alwaysinline` attribute
  /// based on C/C++ attributes or other target-specific reasons.
  ///
  /// See previous discussion here:
  /// https://discourse.llvm.org/t/rfc-avoid-inlining-alwaysinline-functions-when-they-cannot-be-inlined/79528
  virtual bool
  wouldInliningViolateFunctionCallABI(const FunctionDecl *Caller,
                                      const FunctionDecl *Callee) const {
    return false;
  }
 
  /// Provides a convenient hook to handle extra target-specific attributes
  /// for the given global.
  /// In OG, the function receives an llvm::GlobalValue. However, functions
  /// and global variables are separate types in Clang IR, so we use a general
  /// mlir::Operation*.
  virtual void setTargetAttributes(const clang::Decl *decl,
                                   mlir::Operation *global,
                                   CIRGenModule &module) const {}
 
  /// Get the CIR calling convention to use for a device kernel entry point
  /// (e.g. an OpenCL/SYCL or CUDA/HIP kernel) on this target.
  virtual cir::CallingConv getDeviceKernelCallingConv() const {
    return cir::CallingConv::C;
  }
 
  virtual bool isScalarizableAsmOperand(CIRGenFunction &cgf,
                                        mlir::Type ty) const {
    return false;
  }
 
  /// Corrects the MLIR type for a given constraint and "usual"
  /// type.
  ///
  /// \returns A new MLIR type, possibly the same as the original
  /// on success
  virtual mlir::Type adjustInlineAsmType(CIRGenFunction &cgf,
                                         llvm::StringRef constraint,
                                         mlir::Type ty) const {
    return ty;
  }
};
 
std::unique_ptr<TargetCIRGenInfo>
createAMDGPUTargetCIRGenInfo(CIRGenTypes &cgt);
 
/// Check if AMDGPU protected visibility is required.
bool requiresAMDGPUProtectedVisibility(const clang::Decl *d,
                                       cir::VisibilityKind visibility);
 
/// Set AMDGPU-specific function attributes for HIP kernels.
void setAMDGPUTargetFunctionAttributes(const clang::Decl *decl,
                                       cir::FuncOp func, CIRGenModule &cgm);
 
std::unique_ptr<TargetCIRGenInfo> createX8664TargetCIRGenInfo(CIRGenTypes &cgt);
 
std::unique_ptr<TargetCIRGenInfo>
createAArch64TargetCIRGenInfo(CIRGenTypes &cgt);
 
std::unique_ptr<TargetCIRGenInfo> createNVPTXTargetCIRGenInfo(CIRGenTypes &cgt);
 
std::unique_ptr<TargetCIRGenInfo> createSPIRVTargetCIRGenInfo(CIRGenTypes &cgt);
 
} // namespace clang::CIRGen
 
#endif // LLVM_CLANG_LIB_CIR_TARGETINFO_H