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 "InputFiles.h"
19 #include "Symbols.h"
20 #include "Target.h"
21 #include "lld/Common/ErrorHandler.h"
22 #include "llvm/Object/ELF.h"
23 #include "llvm/Support/Endian.h"
24 
25 using namespace llvm;
26 using namespace llvm::object;
27 using namespace llvm::support::endian;
28 using namespace llvm::ELF;
29 using namespace lld;
30 using namespace lld::elf;
31 
32 namespace {
33 class MSP430 final : public TargetInfo {
34 public:
35   MSP430();
36   RelExpr getRelExpr(RelType type, const Symbol &s,
37                      const uint8_t *loc) const override;
38   void relocateOne(uint8_t *loc, RelType type, 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::relocateOne(uint8_t *loc, RelType type, uint64_t val) const {
63   switch (type) {
64   case R_MSP430_8:
65     checkIntUInt(loc, val, 8, type);
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, type);
73     write16le(loc, val);
74     break;
75   case R_MSP430_32:
76     checkIntUInt(loc, val, 32, type);
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, type);
82     write16le(loc, (read16le(loc) & 0xFC00) | (offset & 0x3FF));
83     break;
84   }
85   default:
86     error(getErrorLocation(loc) + "unrecognized relocation " + toString(type));
87   }
88 }
89 
90 TargetInfo *elf::getMSP430TargetInfo() {
91   static MSP430 target;
92   return ⌖
93 }
94