llvm/llvm/include/llvm/IR/VFABIDemangler.h

//===- VFABIDemangler.h - Vector Function ABI demangler ------- -*- 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
//
//===----------------------------------------------------------------------===//
//
// This file defines the VFABI demangling utility.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_IR_VFABIDEMANGLER_H
#define LLVM_IR_VFABIDEMANGLER_H

#include "llvm/ADT/SmallVector.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Instructions.h"
#include "llvm/Support/Alignment.h"
#include "llvm/Support/TypeSize.h"

namespace llvm {

/// Describes the type of Parameters
enum class VFParamKind { … };

/// Describes the type of Instruction Set Architecture
enum class VFISAKind { … };

/// Encapsulates information needed to describe a parameter.
///
/// The description of the parameter is not linked directly to
/// OpenMP or any other vector function description. This structure
/// is extendible to handle other paradigms that describe vector
/// functions and their parameters.
struct VFParameter { … };

/// Contains the information about the kind of vectorization
/// available.
///
/// This object in independent on the paradigm used to
/// represent vector functions. in particular, it is not attached to
/// any target-specific ABI.
struct VFShape { … };

/// Holds the VFShape for a specific scalar to vector function mapping.
struct VFInfo { … };

namespace VFABI {
/// LLVM Internal VFABI ISA token for vector functions.
static constexpr char const *_LLVM_ = …;
/// Prefix for internal name redirection for vector function that
/// tells the compiler to scalarize the call using the scalar name
/// of the function. For example, a mangled name like
/// `_ZGV_LLVM_N2v_foo(_LLVM_Scalarize_foo)` would tell the
/// vectorizer to vectorize the scalar call `foo`, and to scalarize
/// it once vectorization is done.
static constexpr char const *_LLVM_Scalarize_ = …;

/// Function to construct a VFInfo out of a mangled names in the
/// following format:
///
/// <VFABI_name>{(<redirection>)}
///
/// where <VFABI_name> is the name of the vector function, mangled according
/// to the rules described in the Vector Function ABI of the target vector
/// extension (or <isa> from now on). The <VFABI_name> is in the following
/// format:
///
/// _ZGV<isa><mask><vlen><parameters>_<scalarname>[(<redirection>)]
///
/// This methods support demangling rules for the following <isa>:
///
/// * AArch64: https://developer.arm.com/docs/101129/latest
///
/// * x86 (libmvec): https://sourceware.org/glibc/wiki/libmvec and
///  https://sourceware.org/glibc/wiki/libmvec?action=AttachFile&do=view&target=VectorABI.txt
///
/// \param MangledName -> input string in the format
/// _ZGV<isa><mask><vlen><parameters>_<scalarname>[(<redirection>)].
/// \param FTy -> FunctionType of the scalar function which we're trying to find
/// a vectorized variant for. This is required to determine the vectorization
/// factor for scalable vectors, since the mangled name doesn't encode that;
/// it needs to be derived from the widest element types of vector arguments
/// or return values.
std::optional<VFInfo> tryDemangleForVFABI(StringRef MangledName,
                                          const FunctionType *FTy);

/// Retrieve the `VFParamKind` from a string token.
VFParamKind getVFParamKindFromString(const StringRef Token);

// Name of the attribute where the variant mappings are stored.
static constexpr char const *MappingsAttrName = …;

/// Populates a set of strings representing the Vector Function ABI variants
/// associated to the CallInst CI. If the CI does not contain the
/// vector-function-abi-variant attribute, we return without populating
/// VariantMappings, i.e. callers of getVectorVariantNames need not check for
/// the presence of the attribute (see InjectTLIMappings).
void getVectorVariantNames(const CallInst &CI,
                           SmallVectorImpl<std::string> &VariantMappings);

/// Constructs a FunctionType by applying vector function information to the
/// type of a matching scalar function.
/// \param Info gets the vectorization factor (VF) and the VFParamKind of the
/// parameters.
/// \param ScalarFTy gets the Type information of parameters, as it is not
/// stored in \p Info.
/// \returns a pointer to a newly created vector FunctionType
FunctionType *createFunctionType(const VFInfo &Info,
                                 const FunctionType *ScalarFTy);

/// Overwrite the Vector Function ABI variants attribute with the names provide
/// in \p VariantMappings.
void setVectorVariantNames(CallInst *CI, ArrayRef<std::string> VariantMappings);

} // end namespace VFABI

} // namespace llvm

#endif // LLVM_IR_VFABIDEMANGLER_H