llvm/lld/ELF/Arch/AVR.cpp

//===- AVR.cpp ------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// AVR is a Harvard-architecture 8-bit microcontroller designed for small
// baremetal programs. All AVR-family processors have 32 8-bit registers.
// The tiniest AVR has 32 byte RAM and 1 KiB program memory, and the largest
// one supports up to 2^24 data address space and 2^22 code address space.
//
// Since it is a baremetal programming, there's usually no loader to load
// ELF files on AVRs. You are expected to link your program against address
// 0 and pull out a .text section from the result using objcopy, so that you
// can write the linked code to on-chip flush memory. You can do that with
// the following commands:
//
//   ld.lld -Ttext=0 -o foo foo.o
//   objcopy -O binary --only-section=.text foo output.bin
//
// Note that the current AVR support is very preliminary so you can't
// link any useful program yet, though.
//
//===----------------------------------------------------------------------===//

#include "InputFiles.h"
#include "Symbols.h"
#include "Target.h"
#include "Thunks.h"
#include "lld/Common/ErrorHandler.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/Support/Endian.h"

usingnamespacellvm;
usingnamespacellvm::object;
usingnamespacellvm::support::endian;
usingnamespacellvm::ELF;
usingnamespacelld;
usingnamespacelld::elf;

namespace {
class AVR final : public TargetInfo { … };
} // namespace

RelExpr AVR::getRelExpr(RelType type, const Symbol &s,
                        const uint8_t *loc) const { … }

static void writeLDI(uint8_t *loc, uint64_t val) { … }

bool AVR::needsThunk(RelExpr expr, RelType type, const InputFile *file,
                     uint64_t branchAddr, const Symbol &s, int64_t a) const { … }

void AVR::relocate(uint8_t *loc, const Relocation &rel, uint64_t val) const { … }

TargetInfo *elf::getAVRTargetInfo() { … }

static uint32_t getEFlags(InputFile *file) { … }

uint32_t AVR::calcEFlags() const { … }