llvm-project/llvm/lib/MCA/CustomBehaviour.cpp
Michael Maitland 98e342dca2 [RISCV][llvm-mca] Use LMUL Instruments to provide more accurate reports on RISCV
On x86 and AArch, SIMD instructions encode all of the scheduling information in the instruction
itself. For example, VADD.I16 q0, q1, q2 is a neon instruction that operates on 16-bit integer
elements stored in 128-bit Q registers, which leads to eight 16-bit lanes in parallel. This kind
of information impacts how the instruction takes to execute and what dependencies this may cause.

On RISCV however, the data that impacts scheduling is encoded in CSR registers such as vtype or
vl, in addition with the instruction itself. But MCA does not track or use the data in these
registers. This patch fixes this problem by introducing Instruments into MCA.

* Replace `CodeRegions` with `AnalysisRegions`
* Add `Instrument` and `InstrumentManager`
* Add `InstrumentRegions`
* Add RISCV Instrument and `InstrumentManager`
* Parse `Instruments` in driver
* Use instruments to override schedule class
* RISCV use lmul instrument to override schedule class
* Fix unit tests to pass empty instruments
* Add -ignore-im clopt to disable this change

A prior version of this patch was commited in 5e82ee5373. 2323a4ee61 reverted
that change because the unit test files caused build errors. The change with fixes
were committed in b88b8307bf but reverted once again e8e92c8313 due to more
build errors.

This commit adds the prior changes and fixes the build error.

Differential Revision: https://reviews.llvm.org/D137440
2022-11-18 09:55:15 -08:00

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1.9 KiB
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//===--------------------- CustomBehaviour.cpp ------------------*- 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
///
/// This file implements methods from the CustomBehaviour interface.
///
//===----------------------------------------------------------------------===//
#include "llvm/MCA/CustomBehaviour.h"
namespace llvm {
namespace mca {
CustomBehaviour::~CustomBehaviour() = default;
unsigned CustomBehaviour::checkCustomHazard(ArrayRef<InstRef> IssuedInst,
const InstRef &IR) {
// 0 signifies that there are no hazards that need to be waited on
return 0;
}
std::vector<std::unique_ptr<View>>
CustomBehaviour::getStartViews(llvm::MCInstPrinter &IP,
llvm::ArrayRef<llvm::MCInst> Insts) {
return std::vector<std::unique_ptr<View>>();
}
std::vector<std::unique_ptr<View>>
CustomBehaviour::getPostInstrInfoViews(llvm::MCInstPrinter &IP,
llvm::ArrayRef<llvm::MCInst> Insts) {
return std::vector<std::unique_ptr<View>>();
}
std::vector<std::unique_ptr<View>>
CustomBehaviour::getEndViews(llvm::MCInstPrinter &IP,
llvm::ArrayRef<llvm::MCInst> Insts) {
return std::vector<std::unique_ptr<View>>();
}
SharedInstrument InstrumentManager::createInstrument(llvm::StringRef Desc,
llvm::StringRef Data) {
return std::make_shared<Instrument>(Desc, Data);
}
unsigned InstrumentManager::getSchedClassID(
const MCInstrInfo &MCII, const MCInst &MCI,
const llvm::SmallVector<SharedInstrument> &IVec) const {
return MCII.get(MCI.getOpcode()).getSchedClass();
}
} // namespace mca
} // namespace llvm