lld/ELF/Arch/MSP430.cpp

   1 //===- MSP430.cpp ---------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // The MSP430 is a 16-bit microcontroller RISC architecture. The instruction set
  10 // has only 27 core instructions orthogonally augmented with a variety
  11 // of addressing modes for source and destination operands. Entire address space
  12 // of MSP430 is 64KB (the extended MSP430X architecture is not considered here).
  13 // A typical MSP430 MCU has several kilobytes of RAM and ROM, plenty
  14 // of peripherals and is generally optimized for a low power consumption.
  15 //
  16 //===----------------------------------------------------------------------===//
  17
  18 #include "Symbols.h"
  19 #include "Target.h"
  20 #include "lld/Common/ErrorHandler.h"
  21 #include "llvm/BinaryFormat/ELF.h"
  22 #include "llvm/Support/Endian.h"
  23
  24 using namespace llvm;
  25 using namespace llvm::object;
  26 using namespace llvm::support::endian;
  27 using namespace llvm::ELF;
  28 using namespace lld;
  29 using namespace lld::elf;
  30
  31 namespace {
  32 class MSP430 final : public TargetInfo {
  33 public:
  34   MSP430();
  35   RelExpr getRelExpr(RelType type, const Symbol &s,
  36                      const uint8_t *loc) const override;
  37   void relocate(uint8_t *loc, const Relocation &rel,
  38                 uint64_t val) const override;
  39 };
  40 } // namespace
  41
  42 MSP430::MSP430() {
  43   // mov.b #0, r3
  44   trapInstr = {0x43, 0x43, 0x43, 0x43};
  45 }
  46
  47 RelExpr MSP430::getRelExpr(RelType type, const Symbol &s,
  48                            const uint8_t *loc) const {
  49   switch (type) {
  50   case R_MSP430_10_PCREL:
  51   case R_MSP430_16_PCREL:
  52   case R_MSP430_16_PCREL_BYTE:
  53   case R_MSP430_2X_PCREL:
  54   case R_MSP430_RL_PCREL:
  55   case R_MSP430_SYM_DIFF:
  56     return R_PC;
  57   default:
  58     return R_ABS;
  59   }
  60 }
  61
  62 void MSP430::relocate(uint8_t *loc, const Relocation &rel, uint64_t val) const {
  63   switch (rel.type) {
  64   case R_MSP430_8:
  65     checkIntUInt(loc, val, 8, rel);
  66     *loc = val;
  67     break;
  68   case R_MSP430_16:
  69   case R_MSP430_16_PCREL:
  70   case R_MSP430_16_BYTE:
  71   case R_MSP430_16_PCREL_BYTE:
  72     checkIntUInt(loc, val, 16, rel);
  73     write16le(loc, val);
  74     break;
  75   case R_MSP430_32:
  76     checkIntUInt(loc, val, 32, rel);
  77     write32le(loc, val);
  78     break;
  79   case R_MSP430_10_PCREL: {
  80     int16_t offset = ((int16_t)val >> 1) - 1;
  81     checkInt(loc, offset, 10, rel);
  82     write16le(loc, (read16le(loc) & 0xFC00) | (offset & 0x3FF));
  83     break;
  84   }
  85   default:
  86     error(getErrorLocation(loc) + "unrecognized relocation " +
  87           toString(rel.type));
  88   }
  89 }
  90
  91 TargetInfo *elf::getMSP430TargetInfo() {
  92   static MSP430 target;
  93   return &target;
  94 }