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llvm-mirror/lib/Target/BPF/BPFSubtarget.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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//===-- BPFSubtarget.cpp - BPF 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 BPF specific subclass of TargetSubtargetInfo.
//
//===----------------------------------------------------------------------===//
#include "BPFSubtarget.h"
#include "BPF.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/TargetRegistry.h"
using namespace llvm;
#define DEBUG_TYPE "bpf-subtarget"
#define GET_SUBTARGETINFO_TARGET_DESC
#define GET_SUBTARGETINFO_CTOR
#include "BPFGenSubtargetInfo.inc"
void BPFSubtarget::anchor() {}
BPFSubtarget &BPFSubtarget::initializeSubtargetDependencies(StringRef CPU,
StringRef FS) {
initializeEnvironment();
initSubtargetFeatures(CPU, FS);
ParseSubtargetFeatures(CPU, /*TuneCPU*/ CPU, FS);
return *this;
}
void BPFSubtarget::initializeEnvironment() {
HasJmpExt = false;
HasJmp32 = false;
HasAlu32 = false;
UseDwarfRIS = false;
}
void BPFSubtarget::initSubtargetFeatures(StringRef CPU, StringRef FS) {
if (CPU == "probe")
CPU = sys::detail::getHostCPUNameForBPF();
if (CPU == "generic" || CPU == "v1")
return;
if (CPU == "v2") {
HasJmpExt = true;
return;
}
if (CPU == "v3") {
HasJmpExt = true;
HasJmp32 = true;
HasAlu32 = true;
return;
}
}
BPFSubtarget::BPFSubtarget(const Triple &TT, const std::string &CPU,
const std::string &FS, const TargetMachine &TM)
: BPFGenSubtargetInfo(TT, CPU, /*TuneCPU*/ CPU, FS), InstrInfo(),
FrameLowering(initializeSubtargetDependencies(CPU, FS)),
TLInfo(TM, *this) {}