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llvm-mirror/lib/Target/AVR/AVRSubtarget.cpp
Craig Topper 10839866a1 [X86][MC][Target] Initial backend support a tune CPU to support -mtune
This patch implements initial backend support for a -mtune CPU controlled by a "tune-cpu" function attribute. If the attribute is not present X86 will use the resolved CPU from target-cpu attribute or command line.

This patch adds MC layer support a tune CPU. Each CPU now has two sets of features stored in their GenSubtargetInfo.inc tables . These features lists are passed separately to the Processor and ProcessorModel classes in tablegen. The tune list defaults to an empty list to avoid changes to non-X86. This annoyingly increases the size of static tables on all target as we now store 24 more bytes per CPU. I haven't quantified the overall impact, but I can if we're concerned.

One new test is added to X86 to show a few tuning features with mismatched tune-cpu and target-cpu/target-feature attributes to demonstrate independent control. Another new test is added to demonstrate that the scheduler model follows the tune CPU.

I have not added a -mtune to llc/opt or MC layer command line yet. With no attributes we'll just use the -mcpu for both. MC layer tools will always follow the normal CPU for tuning.

Differential Revision: https://reviews.llvm.org/D85165
2020-08-14 15:31:50 -07:00

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//===-- AVRSubtarget.cpp - AVR Subtarget Information ----------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements the AVR specific subclass of TargetSubtargetInfo.
//
//===----------------------------------------------------------------------===//
#include "AVRSubtarget.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/Support/TargetRegistry.h"
#include "AVR.h"
#include "AVRTargetMachine.h"
#include "MCTargetDesc/AVRMCTargetDesc.h"
#define DEBUG_TYPE "avr-subtarget"
#define GET_SUBTARGETINFO_TARGET_DESC
#define GET_SUBTARGETINFO_CTOR
#include "AVRGenSubtargetInfo.inc"
namespace llvm {
AVRSubtarget::AVRSubtarget(const Triple &TT, const std::string &CPU,
const std::string &FS, const AVRTargetMachine &TM)
: AVRGenSubtargetInfo(TT, CPU, /*TuneCPU*/ CPU, FS), ELFArch(0),
// Subtarget features
m_hasSRAM(false), m_hasJMPCALL(false), m_hasIJMPCALL(false),
m_hasEIJMPCALL(false), m_hasADDSUBIW(false), m_hasSmallStack(false),
m_hasMOVW(false), m_hasLPM(false), m_hasLPMX(false), m_hasELPM(false),
m_hasELPMX(false), m_hasSPM(false), m_hasSPMX(false), m_hasDES(false),
m_supportsRMW(false), m_supportsMultiplication(false), m_hasBREAK(false),
m_hasTinyEncoding(false), m_hasMemMappedGPR(false),
m_FeatureSetDummy(false),
InstrInfo(), FrameLowering(),
TLInfo(TM, initializeSubtargetDependencies(CPU, FS, TM)), TSInfo() {
// Parse features string.
ParseSubtargetFeatures(CPU, /*TuneCPU*/ CPU, FS);
}
AVRSubtarget &
AVRSubtarget::initializeSubtargetDependencies(StringRef CPU, StringRef FS,
const TargetMachine &TM) {
// Parse features string.
ParseSubtargetFeatures(CPU, /*TuneCPU*/ CPU, FS);
return *this;
}
} // end of namespace llvm