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llvm-mca is an LLVM based performance analysis tool that can be used to statically measure the performance of code, and to help triage potential problems with target scheduling models. llvm-mca uses information which is already available in LLVM (e.g. scheduling models) to statically measure the performance of machine code in a specific cpu. Performance is measured in terms of throughput as well as processor resource consumption. The tool currently works for processors with an out-of-order backend, for which there is a scheduling model available in LLVM. The main goal of this tool is not just to predict the performance of the code when run on the target, but also help with diagnosing potential performance issues. Given an assembly code sequence, llvm-mca estimates the IPC (instructions per cycle), as well as hardware resources pressure. The analysis and reporting style were mostly inspired by the IACA tool from Intel. This patch is related to the RFC on llvm-dev visible at this link: http://lists.llvm.org/pipermail/llvm-dev/2018-March/121490.html Differential Revision: https://reviews.llvm.org/D43951 llvm-svn: 326998
66 lines
1.9 KiB
C++
66 lines
1.9 KiB
C++
//===--------------------- SourceMgr.h --------------------------*- 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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/// This file implements class SourceMgr. Class SourceMgr abstracts the input
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/// code sequence (a sequence of MCInst), and assings unique identifiers to
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/// every instruction in the sequence.
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///
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TOOLS_LLVM_MCA_SOURCEMGR_H
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#define LLVM_TOOLS_LLVM_MCA_SOURCEMGR_H
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#include "llvm/MC/MCInst.h"
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#include <vector>
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namespace mca {
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typedef std::pair<unsigned, const llvm::MCInst *> InstRef;
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class SourceMgr {
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using InstVec = std::vector<std::unique_ptr<const llvm::MCInst>>;
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InstVec Sequence;
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unsigned Current;
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unsigned Iterations;
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static const unsigned DefaultIterations = 70;
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public:
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SourceMgr(unsigned NumIterations)
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: Current(0),
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Iterations(NumIterations ? NumIterations : DefaultIterations) {}
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unsigned getCurrentIteration() const { return Current / Sequence.size(); }
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unsigned getNumIterations() const { return Iterations; }
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unsigned size() const { return Sequence.size(); }
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const InstVec &getSequence() const { return Sequence; }
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InstVec &getSequence() { return Sequence; }
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bool hasNext() { return Current < (Iterations * size()); }
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void updateNext() { Current++; }
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const InstRef peekNext() const {
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unsigned Index = getCurrentInstructionIndex();
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return InstRef(Current, Sequence[Index].get());
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}
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unsigned getCurrentInstructionIndex() const {
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return Current % Sequence.size();
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}
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const llvm::MCInst &getMCInstFromIndex(unsigned Index) const {
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return *Sequence[Index % size()];
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}
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bool isEmpty() const { return size() == 0; }
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};
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} // namespace mca
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#endif
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