1 //===- InputChunks.cpp ----------------------------------------------------===//
2 //
3 //                             The LLVM Linker
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "InputChunks.h"
11 #include "Config.h"
12 #include "OutputSegment.h"
13 #include "WriterUtils.h"
14 #include "lld/Common/ErrorHandler.h"
15 #include "lld/Common/LLVM.h"
16 #include "llvm/Support/LEB128.h"
17 
18 #define DEBUG_TYPE "lld"
19 
20 using namespace llvm;
21 using namespace llvm::wasm;
22 using namespace llvm::support::endian;
23 using namespace lld;
24 using namespace lld::wasm;
25 
26 std::string lld::toString(const InputChunk *C) {
27   return (toString(C->File) + ":(" + C->getName() + ")").str();
28 }
29 
30 void InputChunk::copyRelocations(const WasmSection &Section) {
31   if (Section.Relocations.empty())
32     return;
33   size_t Start = getInputSectionOffset();
34   size_t Size = getSize();
35   for (const WasmRelocation &R : Section.Relocations)
36     if (R.Offset >= Start && R.Offset < Start + Size)
37       Relocations.push_back(R);
38 }
39 
40 // Copy this input chunk to an mmap'ed output file and apply relocations.
41 void InputChunk::writeTo(uint8_t *Buf) const {
42   // Copy contents
43   memcpy(Buf + OutputOffset, data().data(), data().size());
44 
45   // Apply relocations
46   if (Relocations.empty())
47     return;
48 
49   DEBUG(dbgs() << "applyRelocations: count=" << Relocations.size() << "\n");
50   int32_t Off = OutputOffset - getInputSectionOffset();
51 
52   for (const WasmRelocation &Rel : Relocations) {
53     uint8_t *Loc = Buf + Rel.Offset + Off;
54     uint64_t Value = File->calcNewValue(Rel);
55 
56     DEBUG(dbgs() << "write reloc: type=" << Rel.Type << " index=" << Rel.Index
57                  << " value=" << Value << " offset=" << Rel.Offset << "\n");
58 
59     switch (Rel.Type) {
60     case R_WEBASSEMBLY_TYPE_INDEX_LEB:
61     case R_WEBASSEMBLY_FUNCTION_INDEX_LEB:
62     case R_WEBASSEMBLY_GLOBAL_INDEX_LEB:
63     case R_WEBASSEMBLY_MEMORY_ADDR_LEB:
64       encodeULEB128(Value, Loc, 5);
65       break;
66     case R_WEBASSEMBLY_TABLE_INDEX_SLEB:
67     case R_WEBASSEMBLY_MEMORY_ADDR_SLEB:
68       encodeSLEB128(static_cast<int32_t>(Value), Loc, 5);
69       break;
70     case R_WEBASSEMBLY_TABLE_INDEX_I32:
71     case R_WEBASSEMBLY_MEMORY_ADDR_I32:
72       write32le(Loc, Value);
73       break;
74     default:
75       llvm_unreachable("unknown relocation type");
76     }
77   }
78 }
79 
80 // Copy relocation entries to a given output stream.
81 // This function is used only when a user passes "-r". For a regular link,
82 // we consume relocations instead of copying them to an output file.
83 void InputChunk::writeRelocations(raw_ostream &OS) const {
84   if (Relocations.empty())
85     return;
86 
87   int32_t Off = OutputOffset - getInputSectionOffset();
88   DEBUG(dbgs() << "writeRelocations: " << File->getName()
89                << " offset=" << Twine(Off) << "\n");
90 
91   for (const WasmRelocation &Rel : Relocations) {
92     writeUleb128(OS, Rel.Type, "reloc type");
93     writeUleb128(OS, Rel.Offset + Off, "reloc offset");
94     writeUleb128(OS, File->calcNewIndex(Rel), "reloc index");
95 
96     switch (Rel.Type) {
97     case R_WEBASSEMBLY_MEMORY_ADDR_LEB:
98     case R_WEBASSEMBLY_MEMORY_ADDR_SLEB:
99     case R_WEBASSEMBLY_MEMORY_ADDR_I32:
100       writeUleb128(OS, Rel.Addend, "reloc addend");
101       break;
102     }
103   }
104 }
105 
106 void InputFunction::setOutputIndex(uint32_t Index) {
107   DEBUG(dbgs() << "InputFunction::setOutputIndex: " << getName() << " -> "
108                << Index << "\n");
109   assert(!hasOutputIndex());
110   OutputIndex = Index;
111 }
112 
113 void InputFunction::setTableIndex(uint32_t Index) {
114   DEBUG(dbgs() << "InputFunction::setTableIndex: " << getName() << " -> "
115                << Index << "\n");
116   assert(!hasTableIndex());
117   TableIndex = Index;
118 }
119