9fa425c1ab
AMDGPUPerfHintAnalysis doesn't set the memory bound attribute if FuncInfo::InstCost outweighs MemInstCost even if we have a basic block with relatively high global memory access. GCNSchedStrategy could revert optimal scheduling in favour of occupancy which seems to degrade performance for some kernels. This change introduces the HasDenseGlobalMemAcc metric in the heuristic that makes the analysis more conservative in these cases. This fixes SWDEV-334259/SWDEV-343932 Differential Revision: https://reviews.llvm.org/D129759
59 lines
1.8 KiB
C++
59 lines
1.8 KiB
C++
//===- AMDGPUPerfHintAnalysis.h ---- analysis of memory traffic -*- 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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//
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/// \file
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/// \brief Analyzes if a function potentially memory bound and if a kernel
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/// kernel may benefit from limiting number of waves to reduce cache thrashing.
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///
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_TARGET_AMDGPU_MDGPUPERFHINTANALYSIS_H
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#define LLVM_LIB_TARGET_AMDGPU_MDGPUPERFHINTANALYSIS_H
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#include "llvm/Analysis/CallGraphSCCPass.h"
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#include "llvm/IR/ValueMap.h"
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namespace llvm {
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struct AMDGPUPerfHintAnalysis : public CallGraphSCCPass {
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static char ID;
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public:
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AMDGPUPerfHintAnalysis() : CallGraphSCCPass(ID) {}
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bool runOnSCC(CallGraphSCC &SCC) override;
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.setPreservesAll();
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}
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bool isMemoryBound(const Function *F) const;
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bool needsWaveLimiter(const Function *F) const;
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struct FuncInfo {
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unsigned MemInstCost;
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unsigned InstCost;
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unsigned IAMInstCost; // Indirect access memory instruction count
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unsigned LSMInstCost; // Large stride memory instruction count
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bool HasDenseGlobalMemAcc; // Set if at least 1 basic block has relatively
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// high global memory access
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FuncInfo()
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: MemInstCost(0), InstCost(0), IAMInstCost(0), LSMInstCost(0),
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HasDenseGlobalMemAcc(false) {}
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};
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typedef ValueMap<const Function*, FuncInfo> FuncInfoMap;
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private:
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FuncInfoMap FIM;
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};
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} // namespace llvm
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#endif // LLVM_LIB_TARGET_AMDGPU_MDGPUPERFHINTANALYSIS_H
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