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llvm-mirror/include/llvm/CodeGen/CostTable.h
Simon Pilgrim 41db4b6343 [CostModel] Templatize EntryCost::Cost to allow custom cost metrics
We currently use an unsigned value for our CostTblEntry and TypeConversionCostTblEntry cost tables which is limiting depending on how the target wishes to handle various CostKinds etc.

For instance, targets might wish to store separate instruction count, latency or throughput values etc. On D46276 we have been investigating storing a code snippet to improve latency/throughput cost calculations.

There is a slight problem in that template argument deduction was struggling to match the now templatized Costs[] tables in a ArrayRef constructor - I've added helper wrappers for CostTableLookup/ConvertCostTableLookup which avoids us having to update all existing calls with a template hint.

Differential Revision: https://reviews.llvm.org/D106351
2021-07-20 15:31:39 +01:00

90 lines
2.7 KiB
C++

//===-- CostTable.h - Instruction Cost Table handling -----------*- 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// Cost tables and simple lookup functions
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_CODEGEN_COSTTABLE_H_
#define LLVM_CODEGEN_COSTTABLE_H_
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/MachineValueType.h"
namespace llvm {
/// Cost Table Entry
template <typename CostType>
struct CostTblEntryT {
int ISD;
MVT::SimpleValueType Type;
CostType Cost;
};
using CostTblEntry = CostTblEntryT<unsigned>;
/// Find in cost table.
template <class CostType>
inline const CostTblEntryT<CostType> *
CostTableLookup(ArrayRef<CostTblEntryT<CostType>> Tbl, int ISD, MVT Ty) {
auto I = find_if(Tbl, [=](const CostTblEntryT<CostType> &Entry) {
return ISD == Entry.ISD && Ty == Entry.Type;
});
if (I != Tbl.end())
return I;
// Could not find an entry.
return nullptr;
}
template <size_t N, class CostType>
inline const CostTblEntryT<CostType> *
CostTableLookup(const CostTblEntryT<CostType> (&Table)[N], int ISD, MVT Ty) {
// Wrapper to fix template argument deduction failures.
return CostTableLookup<CostType>(makeArrayRef(Table), ISD, Ty);
}
/// Type Conversion Cost Table
template <typename CostType>
struct TypeConversionCostTblEntryT {
int ISD;
MVT::SimpleValueType Dst;
MVT::SimpleValueType Src;
CostType Cost;
};
using TypeConversionCostTblEntry = TypeConversionCostTblEntryT<unsigned>;
/// Find in type conversion cost table.
template <class CostType>
inline const TypeConversionCostTblEntryT<CostType> *
ConvertCostTableLookup(ArrayRef<TypeConversionCostTblEntryT<CostType>> Tbl,
int ISD, MVT Dst, MVT Src) {
auto I =
find_if(Tbl, [=](const TypeConversionCostTblEntryT<CostType> &Entry) {
return ISD == Entry.ISD && Src == Entry.Src && Dst == Entry.Dst;
});
if (I != Tbl.end())
return I;
// Could not find an entry.
return nullptr;
}
template <size_t N, class CostType>
inline const TypeConversionCostTblEntryT<CostType> *
ConvertCostTableLookup(const TypeConversionCostTblEntryT<CostType> (&Table)[N],
int ISD, MVT Dst, MVT Src) {
// Wrapper to fix template argument deduction failures.
return ConvertCostTableLookup<CostType>(makeArrayRef(Table), ISD, Dst, Src);
}
} // namespace llvm
#endif /* LLVM_CODEGEN_COSTTABLE_H_ */