forked from OSchip/llvm-project
80 lines
2.9 KiB
C++
80 lines
2.9 KiB
C++
//===--------------------- Support.cpp --------------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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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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void computeProcResourceMasks(const MCSchedModel &SM,
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SmallVectorImpl<uint64_t> &Masks) {
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unsigned ProcResourceID = 0;
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// Create a unique bitmask for every processor resource unit.
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// Skip resource at index 0, since it always references 'InvalidUnit'.
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Masks.resize(SM.getNumProcResourceKinds());
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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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}
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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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