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//===--------------------- Support.h ----------------------------*- 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
///
/// Helper functions used by various pipeline components.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_MCA_SUPPORT_H
#define LLVM_MCA_SUPPORT_H
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/MC/MCSchedule.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/MathExtras.h"
namespace llvm {
namespace mca {
template <typename T>
class InstructionError : public ErrorInfo<InstructionError<T>> {
public:
static char ID;
std::string Message;
const T &Inst;
InstructionError(std::string M, const T &MCI)
: Message(std::move(M)), Inst(MCI) {}
void log(raw_ostream &OS) const override { OS << Message; }
std::error_code convertToErrorCode() const override {
return inconvertibleErrorCode();
}
};
template <typename T> char InstructionError<T>::ID;
/// This class represents the number of cycles per resource (fractions of
/// cycles). That quantity is managed here as a ratio, and accessed via the
/// double cast-operator below. The two quantities, number of cycles and
/// number of resources, are kept separate. This is used by the
/// ResourcePressureView to calculate the average resource cycles
/// per instruction/iteration.
class ReleaseAtCycles {
unsigned Numerator, Denominator;
public:
ReleaseAtCycles() : Numerator(0), Denominator(1) {}
ReleaseAtCycles(unsigned Cycles, unsigned ResourceUnits = 1)
: Numerator(Cycles), Denominator(ResourceUnits) {}
operator double() const {
assert(Denominator && "Invalid denominator (must be non-zero).");
return (Denominator == 1) ? Numerator : (double)Numerator / Denominator;
}
unsigned getNumerator() const { return Numerator; }
unsigned getDenominator() const { return Denominator; }
// Add the components of RHS to this instance. Instead of calculating
// the final value here, we keep track of the numerator and denominator
// separately, to reduce floating point error.
ReleaseAtCycles &operator+=(const ReleaseAtCycles &RHS);
};
/// Populates vector Masks with processor resource masks.
///
/// The number of bits set in a mask depends on the processor resource type.
/// Each processor resource mask has at least one bit set. For groups, the
/// number of bits set in the mask is equal to the cardinality of the group plus
/// one. Excluding the most significant bit, the remaining bits in the mask
/// identify processor resources that are part of the group.
///
/// Example:
///
/// ResourceA -- Mask: 0b001
/// ResourceB -- Mask: 0b010
/// ResourceAB -- Mask: 0b100 U (ResourceA::Mask | ResourceB::Mask) == 0b111
///
/// ResourceAB is a processor resource group containing ResourceA and ResourceB.
/// Each resource mask uniquely identifies a resource; both ResourceA and
/// ResourceB only have one bit set.
/// ResourceAB is a group; excluding the most significant bit in the mask, the
/// remaining bits identify the composition of the group.
///
/// Resource masks are used by the ResourceManager to solve set membership
/// problems with simple bit manipulation operations.
void computeProcResourceMasks(const MCSchedModel &SM,
MutableArrayRef<uint64_t> Masks);
// Returns the index of the highest bit set. For resource masks, the position of
// the highest bit set can be used to construct a resource mask identifier.
inline unsigned getResourceStateIndex(uint64_t Mask) {
assert(Mask && "Processor Resource Mask cannot be zero!");
return llvm::Log2_64(Mask);
}
/// Compute the reciprocal block throughput from a set of processor resource
/// cycles. The reciprocal block throughput is computed as the MAX between:
/// - NumMicroOps / DispatchWidth
/// - ProcReleaseAtCycles / #ProcResourceUnits (for every consumed resource).
double computeBlockRThroughput(const MCSchedModel &SM, unsigned DispatchWidth,
unsigned NumMicroOps,
ArrayRef<unsigned> ProcResourceUsage);
} // namespace mca
} // namespace llvm
#endif // LLVM_MCA_SUPPORT_H
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