blob: 3187b4e68c56f3ae31941ef8ae129188c6543868 [file] [log] [blame]
//===-- include/llvm/CodeGen/ByteProvider.h - Map bytes ---------*- 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
// \file
// This file implements ByteProvider. The purpose of ByteProvider is to provide
// a map between a target node's byte (byte position is DestOffset) and the
// source (and byte position) that provides it (in Src and SrcOffset
// respectively) See CodeGen/SelectionDAG/DAGCombiner.cpp MatchLoadCombine
#include <optional>
#include <type_traits>
namespace llvm {
/// Represents known origin of an individual byte in combine pattern. The
/// value of the byte is either constant zero, or comes from memory /
/// some other productive instruction (e.g. arithmetic instructions).
/// Bit manipulation instructions like shifts are not ByteProviders, rather
/// are used to extract Bytes.
template <typename ISelOp> class ByteProvider {
ByteProvider(std::optional<ISelOp> Src, int64_t DestOffset, int64_t SrcOffset)
: Src(Src), DestOffset(DestOffset), SrcOffset(SrcOffset) {}
// TODO -- use constraint in c++20
// Does this type correspond with an operation in selection DAG
template <typename T> class is_op {
using yes = std::true_type;
using no = std::false_type;
// Only allow classes with member function getOpcode
template <typename U>
static auto test(int) -> decltype(std::declval<U>().getOpcode(), yes());
template <typename> static no test(...);
using remove_pointer_t = typename std::remove_pointer<T>::type;
static constexpr bool value =
std::is_same<decltype(test<remove_pointer_t>(0)), yes>::value;
// For constant zero providers Src is set to nullopt. For actual providers
// Src represents the node which originally produced the relevant bits.
std::optional<ISelOp> Src = std::nullopt;
// DestOffset is the offset of the byte in the dest we are trying to map for.
int64_t DestOffset = 0;
// SrcOffset is the offset in the ultimate source node that maps to the
// DestOffset
int64_t SrcOffset = 0;
ByteProvider() = default;
static ByteProvider getSrc(std::optional<ISelOp> Val, int64_t ByteOffset,
int64_t VectorOffset) {
"ByteProviders must contain an operation in selection DAG.");
return ByteProvider(Val, ByteOffset, VectorOffset);
static ByteProvider getConstantZero() {
return ByteProvider<ISelOp>(std::nullopt, 0, 0);
bool isConstantZero() const { return !Src; }
bool hasSrc() const { return Src.has_value(); }
bool hasSameSrc(const ByteProvider &Other) const { return Other.Src == Src; }
bool operator==(const ByteProvider &Other) const {
return Other.Src == Src && Other.DestOffset == DestOffset &&
Other.SrcOffset == SrcOffset;
} // end namespace llvm