| File: | tools/lld/wasm/OutputSections.cpp |
| Warning: | line 114, column 3 Value stored to 'Buf' is never read |
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| 1 | //===- OutputSections.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 "OutputSections.h" |
| 11 | #include "InputChunks.h" |
| 12 | #include "InputFiles.h" |
| 13 | #include "OutputSegment.h" |
| 14 | #include "lld/Common/ErrorHandler.h" |
| 15 | #include "lld/Common/Threads.h" |
| 16 | #include "llvm/ADT/Twine.h" |
| 17 | #include "llvm/Support/LEB128.h" |
| 18 | |
| 19 | #define DEBUG_TYPE"lld" "lld" |
| 20 | |
| 21 | using namespace llvm; |
| 22 | using namespace llvm::wasm; |
| 23 | using namespace lld; |
| 24 | using namespace lld::wasm; |
| 25 | |
| 26 | static StringRef sectionTypeToString(uint32_t SectionType) { |
| 27 | switch (SectionType) { |
| 28 | case WASM_SEC_CUSTOM: |
| 29 | return "CUSTOM"; |
| 30 | case WASM_SEC_TYPE: |
| 31 | return "TYPE"; |
| 32 | case WASM_SEC_IMPORT: |
| 33 | return "IMPORT"; |
| 34 | case WASM_SEC_FUNCTION: |
| 35 | return "FUNCTION"; |
| 36 | case WASM_SEC_TABLE: |
| 37 | return "TABLE"; |
| 38 | case WASM_SEC_MEMORY: |
| 39 | return "MEMORY"; |
| 40 | case WASM_SEC_GLOBAL: |
| 41 | return "GLOBAL"; |
| 42 | case WASM_SEC_EXPORT: |
| 43 | return "EXPORT"; |
| 44 | case WASM_SEC_START: |
| 45 | return "START"; |
| 46 | case WASM_SEC_ELEM: |
| 47 | return "ELEM"; |
| 48 | case WASM_SEC_CODE: |
| 49 | return "CODE"; |
| 50 | case WASM_SEC_DATA: |
| 51 | return "DATA"; |
| 52 | default: |
| 53 | fatal("invalid section type"); |
| 54 | } |
| 55 | } |
| 56 | |
| 57 | std::string lld::toString(const OutputSection &Section) { |
| 58 | std::string rtn = Section.getSectionName(); |
| 59 | if (!Section.Name.empty()) |
| 60 | rtn += "(" + Section.Name + ")"; |
| 61 | return rtn; |
| 62 | } |
| 63 | |
| 64 | std::string OutputSection::getSectionName() const { |
| 65 | return sectionTypeToString(Type); |
| 66 | } |
| 67 | |
| 68 | std::string SubSection::getSectionName() const { |
| 69 | return std::string("subsection <type=") + std::to_string(Type) + ">"; |
| 70 | } |
| 71 | |
| 72 | void OutputSection::createHeader(size_t BodySize) { |
| 73 | raw_string_ostream OS(Header); |
| 74 | debugWrite(OS.tell(), "section type [" + Twine(getSectionName()) + "]"); |
| 75 | encodeULEB128(Type, OS); |
| 76 | writeUleb128(OS, BodySize, "section size"); |
| 77 | OS.flush(); |
| 78 | log("createHeader: " + toString(*this) + " body=" + Twine(BodySize) + |
| 79 | " total=" + Twine(getSize())); |
| 80 | } |
| 81 | |
| 82 | CodeSection::CodeSection(ArrayRef<InputFunction *> Functions) |
| 83 | : OutputSection(WASM_SEC_CODE), Functions(Functions) { |
| 84 | assert(Functions.size() > 0)(static_cast <bool> (Functions.size() > 0) ? void (0 ) : __assert_fail ("Functions.size() > 0", "/build/llvm-toolchain-snapshot-7~svn326246/tools/lld/wasm/OutputSections.cpp" , 84, __extension__ __PRETTY_FUNCTION__)); |
| 85 | |
| 86 | raw_string_ostream OS(CodeSectionHeader); |
| 87 | writeUleb128(OS, Functions.size(), "function count"); |
| 88 | OS.flush(); |
| 89 | BodySize = CodeSectionHeader.size(); |
| 90 | |
| 91 | for (InputChunk *Func : Functions) { |
| 92 | Func->OutputOffset = BodySize; |
| 93 | BodySize += Func->getSize(); |
| 94 | } |
| 95 | |
| 96 | createHeader(BodySize); |
| 97 | } |
| 98 | |
| 99 | void CodeSection::writeTo(uint8_t *Buf) { |
| 100 | log("writing " + toString(*this)); |
| 101 | log(" size=" + Twine(getSize())); |
| 102 | log(" headersize=" + Twine(Header.size())); |
| 103 | log(" codeheadersize=" + Twine(CodeSectionHeader.size())); |
| 104 | Buf += Offset; |
| 105 | |
| 106 | // Write section header |
| 107 | memcpy(Buf, Header.data(), Header.size()); |
| 108 | Buf += Header.size(); |
| 109 | |
| 110 | uint8_t *ContentsStart = Buf; |
| 111 | |
| 112 | // Write code section headers |
| 113 | memcpy(Buf, CodeSectionHeader.data(), CodeSectionHeader.size()); |
| 114 | Buf += CodeSectionHeader.size(); |
Value stored to 'Buf' is never read | |
| 115 | |
| 116 | // Write code section bodies |
| 117 | parallelForEach(Functions, [ContentsStart](const InputChunk *Chunk) { |
| 118 | Chunk->writeTo(ContentsStart); |
| 119 | }); |
| 120 | } |
| 121 | |
| 122 | uint32_t CodeSection::numRelocations() const { |
| 123 | uint32_t Count = 0; |
| 124 | for (const InputChunk *Func : Functions) |
| 125 | Count += Func->NumRelocations(); |
| 126 | return Count; |
| 127 | } |
| 128 | |
| 129 | void CodeSection::writeRelocations(raw_ostream &OS) const { |
| 130 | for (const InputChunk *C : Functions) |
| 131 | C->writeRelocations(OS); |
| 132 | } |
| 133 | |
| 134 | DataSection::DataSection(ArrayRef<OutputSegment *> Segments) |
| 135 | : OutputSection(WASM_SEC_DATA), Segments(Segments) { |
| 136 | raw_string_ostream OS(DataSectionHeader); |
| 137 | |
| 138 | writeUleb128(OS, Segments.size(), "data segment count"); |
| 139 | OS.flush(); |
| 140 | BodySize = DataSectionHeader.size(); |
| 141 | |
| 142 | for (OutputSegment *Segment : Segments) { |
| 143 | raw_string_ostream OS(Segment->Header); |
| 144 | writeUleb128(OS, 0, "memory index"); |
| 145 | writeUleb128(OS, WASM_OPCODE_I32_CONST, "opcode:i32const"); |
| 146 | writeSleb128(OS, Segment->StartVA, "memory offset"); |
| 147 | writeUleb128(OS, WASM_OPCODE_END, "opcode:end"); |
| 148 | writeUleb128(OS, Segment->Size, "segment size"); |
| 149 | OS.flush(); |
| 150 | Segment->setSectionOffset(BodySize); |
| 151 | BodySize += Segment->Header.size() + Segment->Size; |
| 152 | log("Data segment: size=" + Twine(Segment->Size)); |
| 153 | for (InputSegment *InputSeg : Segment->InputSegments) |
| 154 | InputSeg->OutputOffset = Segment->getSectionOffset() + |
| 155 | Segment->Header.size() + |
| 156 | InputSeg->OutputSegmentOffset; |
| 157 | } |
| 158 | |
| 159 | createHeader(BodySize); |
| 160 | } |
| 161 | |
| 162 | void DataSection::writeTo(uint8_t *Buf) { |
| 163 | log("writing " + toString(*this) + " size=" + Twine(getSize()) + |
| 164 | " body=" + Twine(BodySize)); |
| 165 | Buf += Offset; |
| 166 | |
| 167 | // Write section header |
| 168 | memcpy(Buf, Header.data(), Header.size()); |
| 169 | Buf += Header.size(); |
| 170 | |
| 171 | uint8_t *ContentsStart = Buf; |
| 172 | |
| 173 | // Write data section headers |
| 174 | memcpy(Buf, DataSectionHeader.data(), DataSectionHeader.size()); |
| 175 | |
| 176 | parallelForEach(Segments, [ContentsStart](const OutputSegment *Segment) { |
| 177 | // Write data segment header |
| 178 | uint8_t *SegStart = ContentsStart + Segment->getSectionOffset(); |
| 179 | memcpy(SegStart, Segment->Header.data(), Segment->Header.size()); |
| 180 | |
| 181 | // Write segment data payload |
| 182 | for (const InputChunk *Chunk : Segment->InputSegments) |
| 183 | Chunk->writeTo(ContentsStart); |
| 184 | }); |
| 185 | } |
| 186 | |
| 187 | uint32_t DataSection::numRelocations() const { |
| 188 | uint32_t Count = 0; |
| 189 | for (const OutputSegment *Seg : Segments) |
| 190 | for (const InputChunk *InputSeg : Seg->InputSegments) |
| 191 | Count += InputSeg->NumRelocations(); |
| 192 | return Count; |
| 193 | } |
| 194 | |
| 195 | void DataSection::writeRelocations(raw_ostream &OS) const { |
| 196 | for (const OutputSegment *Seg : Segments) |
| 197 | for (const InputChunk *C : Seg->InputSegments) |
| 198 | C->writeRelocations(OS); |
| 199 | } |