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 relocate(uint8_t *loc, const Relocation &rel,
39                 uint64_t val) const override;
40 };
41 } // namespace
42 
43 MSP430::MSP430() {
44   // mov.b #0, r3
45   trapInstr = {0x43, 0x43, 0x43, 0x43};
46 }
47 
48 RelExpr MSP430::getRelExpr(RelType type, const Symbol &s,
49                            const uint8_t *loc) const {
50   switch (type) {
51   case R_MSP430_10_PCREL:
52   case R_MSP430_16_PCREL:
53   case R_MSP430_16_PCREL_BYTE:
54   case R_MSP430_2X_PCREL:
55   case R_MSP430_RL_PCREL:
56   case R_MSP430_SYM_DIFF:
57     return R_PC;
58   default:
59     return R_ABS;
60   }
61 }
62 
63 void MSP430::relocate(uint8_t *loc, const Relocation &rel, uint64_t val) const {
64   switch (rel.type) {
65   case R_MSP430_8:
66     checkIntUInt(loc, val, 8, rel);
67     *loc = val;
68     break;
69   case R_MSP430_16:
70   case R_MSP430_16_PCREL:
71   case R_MSP430_16_BYTE:
72   case R_MSP430_16_PCREL_BYTE:
73     checkIntUInt(loc, val, 16, rel);
74     write16le(loc, val);
75     break;
76   case R_MSP430_32:
77     checkIntUInt(loc, val, 32, rel);
78     write32le(loc, val);
79     break;
80   case R_MSP430_10_PCREL: {
81     int16_t offset = ((int16_t)val >> 1) - 1;
82     checkInt(loc, offset, 10, rel);
83     write16le(loc, (read16le(loc) & 0xFC00) | (offset & 0x3FF));
84     break;
85   }
86   default:
87     error(getErrorLocation(loc) + "unrecognized relocation " +
88           toString(rel.type));
89   }
90 }
91 
92 TargetInfo *elf::getMSP430TargetInfo() {
93   static MSP430 target;
94   return ⌖
95 }
96