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to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
94 lines
3.4 KiB
C++
94 lines
3.4 KiB
C++
//===--------------------- Support.cpp --------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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/// \file
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///
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/// This file implements a few helper functions used by various pipeline
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/// components.
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///
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//===----------------------------------------------------------------------===//
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#include "llvm/MCA/Support.h"
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#include "llvm/MC/MCSchedule.h"
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namespace llvm {
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namespace mca {
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#define DEBUG_TYPE "llvm-mca"
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void computeProcResourceMasks(const MCSchedModel &SM,
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MutableArrayRef<uint64_t> Masks) {
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unsigned ProcResourceID = 0;
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assert(Masks.size() == SM.getNumProcResourceKinds() &&
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"Invalid number of elements");
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// Resource at index 0 is the 'InvalidUnit'. Set an invalid mask for it.
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Masks[0] = 0;
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// Create a unique bitmask for every processor resource unit.
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for (unsigned I = 1, E = SM.getNumProcResourceKinds(); I < E; ++I) {
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const MCProcResourceDesc &Desc = *SM.getProcResource(I);
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if (Desc.SubUnitsIdxBegin)
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continue;
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Masks[I] = 1ULL << ProcResourceID;
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ProcResourceID++;
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}
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// Create a unique bitmask for every processor resource group.
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for (unsigned I = 1, E = SM.getNumProcResourceKinds(); I < E; ++I) {
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const MCProcResourceDesc &Desc = *SM.getProcResource(I);
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if (!Desc.SubUnitsIdxBegin)
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continue;
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Masks[I] = 1ULL << ProcResourceID;
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for (unsigned U = 0; U < Desc.NumUnits; ++U) {
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uint64_t OtherMask = Masks[Desc.SubUnitsIdxBegin[U]];
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Masks[I] |= OtherMask;
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}
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ProcResourceID++;
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}
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#ifndef NDEBUG
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LLVM_DEBUG(dbgs() << "\nProcessor resource masks:"
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<< "\n");
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for (unsigned I = 0, E = SM.getNumProcResourceKinds(); I < E; ++I) {
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const MCProcResourceDesc &Desc = *SM.getProcResource(I);
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LLVM_DEBUG(dbgs() << '[' << I << "] " << Desc.Name << " - " << Masks[I]
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<< '\n');
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}
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#endif
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}
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double computeBlockRThroughput(const MCSchedModel &SM, unsigned DispatchWidth,
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unsigned NumMicroOps,
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ArrayRef<unsigned> ProcResourceUsage) {
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// The block throughput is bounded from above by the hardware dispatch
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// throughput. That is because the DispatchWidth is an upper bound on the
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// number of opcodes that can be part of a single dispatch group.
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double Max = static_cast<double>(NumMicroOps) / DispatchWidth;
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// The block throughput is also limited by the amount of hardware parallelism.
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// The number of available resource units affects the resource pressure
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// distribution, as well as how many blocks can be executed every cycle.
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for (unsigned I = 0, E = SM.getNumProcResourceKinds(); I < E; ++I) {
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unsigned ResourceCycles = ProcResourceUsage[I];
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if (!ResourceCycles)
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continue;
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const MCProcResourceDesc &MCDesc = *SM.getProcResource(I);
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double Throughput = static_cast<double>(ResourceCycles) / MCDesc.NumUnits;
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Max = std::max(Max, Throughput);
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}
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// The block reciprocal throughput is computed as the MAX of:
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// - (NumMicroOps / DispatchWidth)
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// - (NumUnits / ResourceCycles) for every consumed processor resource.
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return Max;
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}
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} // namespace mca
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} // namespace llvm
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