forked from OSchip/llvm-project
285 lines
8.0 KiB
C++
285 lines
8.0 KiB
C++
//===- OutputSections.cpp -------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "OutputSections.h"
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#include "InputChunks.h"
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#include "InputFiles.h"
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#include "OutputSegment.h"
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#include "WriterUtils.h"
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#include "lld/Common/ErrorHandler.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/Support/LEB128.h"
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#include "llvm/Support/Parallel.h"
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#define DEBUG_TYPE "lld"
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using namespace llvm;
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using namespace llvm::wasm;
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namespace lld {
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// Returns a string, e.g. "FUNCTION(.text)".
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std::string toString(const wasm::OutputSection &sec) {
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if (!sec.name.empty())
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return (sec.getSectionName() + "(" + sec.name + ")").str();
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return std::string(sec.getSectionName());
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}
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namespace wasm {
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static StringRef sectionTypeToString(uint32_t sectionType) {
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switch (sectionType) {
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case WASM_SEC_CUSTOM:
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return "CUSTOM";
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case WASM_SEC_TYPE:
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return "TYPE";
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case WASM_SEC_IMPORT:
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return "IMPORT";
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case WASM_SEC_FUNCTION:
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return "FUNCTION";
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case WASM_SEC_TABLE:
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return "TABLE";
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case WASM_SEC_MEMORY:
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return "MEMORY";
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case WASM_SEC_GLOBAL:
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return "GLOBAL";
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case WASM_SEC_EVENT:
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return "EVENT";
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case WASM_SEC_EXPORT:
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return "EXPORT";
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case WASM_SEC_START:
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return "START";
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case WASM_SEC_ELEM:
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return "ELEM";
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case WASM_SEC_CODE:
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return "CODE";
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case WASM_SEC_DATA:
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return "DATA";
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case WASM_SEC_DATACOUNT:
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return "DATACOUNT";
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default:
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fatal("invalid section type");
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}
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}
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StringRef OutputSection::getSectionName() const {
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return sectionTypeToString(type);
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}
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void OutputSection::createHeader(size_t bodySize) {
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raw_string_ostream os(header);
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debugWrite(os.tell(), "section type [" + getSectionName() + "]");
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encodeULEB128(type, os);
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writeUleb128(os, bodySize, "section size");
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os.flush();
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log("createHeader: " + toString(*this) + " body=" + Twine(bodySize) +
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" total=" + Twine(getSize()));
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}
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void CodeSection::finalizeContents() {
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raw_string_ostream os(codeSectionHeader);
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writeUleb128(os, functions.size(), "function count");
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os.flush();
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bodySize = codeSectionHeader.size();
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for (InputFunction *func : functions) {
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func->outputSec = this;
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func->outSecOff = bodySize;
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func->calculateSize();
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// All functions should have a non-empty body at this point
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assert(func->getSize());
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bodySize += func->getSize();
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}
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createHeader(bodySize);
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}
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void CodeSection::writeTo(uint8_t *buf) {
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log("writing " + toString(*this));
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log(" size=" + Twine(getSize()));
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log(" headersize=" + Twine(header.size()));
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log(" codeheadersize=" + Twine(codeSectionHeader.size()));
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buf += offset;
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// Write section header
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memcpy(buf, header.data(), header.size());
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buf += header.size();
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// Write code section headers
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memcpy(buf, codeSectionHeader.data(), codeSectionHeader.size());
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// Write code section bodies
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for (const InputChunk *chunk : functions)
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chunk->writeTo(buf);
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}
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uint32_t CodeSection::getNumRelocations() const {
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uint32_t count = 0;
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for (const InputChunk *func : functions)
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count += func->getNumRelocations();
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return count;
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}
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void CodeSection::writeRelocations(raw_ostream &os) const {
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for (const InputChunk *c : functions)
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c->writeRelocations(os);
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}
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void DataSection::finalizeContents() {
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raw_string_ostream os(dataSectionHeader);
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unsigned segmentCount =
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std::count_if(segments.begin(), segments.end(),
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[](OutputSegment *segment) { return !segment->isBss; });
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#ifndef NDEBUG
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unsigned activeCount = std::count_if(
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segments.begin(), segments.end(), [](OutputSegment *segment) {
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return (segment->initFlags & WASM_DATA_SEGMENT_IS_PASSIVE) == 0;
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});
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#endif
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assert((!config->isPic || activeCount <= 1) &&
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"Currenly only a single data segment is supported in PIC mode");
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writeUleb128(os, segmentCount, "data segment count");
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os.flush();
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bodySize = dataSectionHeader.size();
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for (OutputSegment *segment : segments) {
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if (segment->isBss)
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continue;
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raw_string_ostream os(segment->header);
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writeUleb128(os, segment->initFlags, "init flags");
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if (segment->initFlags & WASM_DATA_SEGMENT_HAS_MEMINDEX)
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writeUleb128(os, 0, "memory index");
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if ((segment->initFlags & WASM_DATA_SEGMENT_IS_PASSIVE) == 0) {
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WasmInitExpr initExpr;
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if (config->isPic) {
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initExpr.Opcode = WASM_OPCODE_GLOBAL_GET;
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initExpr.Value.Global = WasmSym::memoryBase->getGlobalIndex();
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} else if (config->is64.getValueOr(false)) {
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initExpr.Opcode = WASM_OPCODE_I64_CONST;
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initExpr.Value.Int64 = static_cast<int64_t>(segment->startVA);
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} else {
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initExpr.Opcode = WASM_OPCODE_I32_CONST;
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initExpr.Value.Int32 = static_cast<int32_t>(segment->startVA);
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}
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writeInitExpr(os, initExpr);
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}
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writeUleb128(os, segment->size, "segment size");
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os.flush();
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segment->sectionOffset = bodySize;
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bodySize += segment->header.size() + segment->size;
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log("Data segment: size=" + Twine(segment->size) + ", startVA=" +
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Twine::utohexstr(segment->startVA) + ", name=" + segment->name);
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for (InputSegment *inputSeg : segment->inputSegments) {
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inputSeg->outputSec = this;
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inputSeg->outSecOff = segment->sectionOffset + segment->header.size() +
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inputSeg->outputSegmentOffset;
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}
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}
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createHeader(bodySize);
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}
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void DataSection::writeTo(uint8_t *buf) {
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log("writing " + toString(*this) + " size=" + Twine(getSize()) +
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" body=" + Twine(bodySize));
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buf += offset;
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// Write section header
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memcpy(buf, header.data(), header.size());
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buf += header.size();
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// Write data section headers
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memcpy(buf, dataSectionHeader.data(), dataSectionHeader.size());
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for (const OutputSegment *segment : segments) {
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if (segment->isBss)
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continue;
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// Write data segment header
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uint8_t *segStart = buf + segment->sectionOffset;
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memcpy(segStart, segment->header.data(), segment->header.size());
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// Write segment data payload
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for (const InputChunk *chunk : segment->inputSegments)
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chunk->writeTo(buf);
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}
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}
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uint32_t DataSection::getNumRelocations() const {
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uint32_t count = 0;
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for (const OutputSegment *seg : segments)
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for (const InputChunk *inputSeg : seg->inputSegments)
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count += inputSeg->getNumRelocations();
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return count;
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}
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void DataSection::writeRelocations(raw_ostream &os) const {
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for (const OutputSegment *seg : segments)
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for (const InputChunk *c : seg->inputSegments)
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c->writeRelocations(os);
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}
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bool DataSection::isNeeded() const {
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for (const OutputSegment *seg : segments)
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if (!seg->isBss)
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return true;
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return false;
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}
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void CustomSection::finalizeContents() {
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raw_string_ostream os(nameData);
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encodeULEB128(name.size(), os);
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os << name;
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os.flush();
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for (InputSection *section : inputSections) {
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assert(!section->discarded);
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section->outputSec = this;
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section->outSecOff = payloadSize;
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payloadSize += section->getSize();
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}
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createHeader(payloadSize + nameData.size());
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}
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void CustomSection::writeTo(uint8_t *buf) {
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log("writing " + toString(*this) + " size=" + Twine(getSize()) +
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" chunks=" + Twine(inputSections.size()));
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assert(offset);
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buf += offset;
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// Write section header
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memcpy(buf, header.data(), header.size());
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buf += header.size();
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memcpy(buf, nameData.data(), nameData.size());
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buf += nameData.size();
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// Write custom sections payload
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for (const InputSection *section : inputSections)
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section->writeTo(buf);
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}
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uint32_t CustomSection::getNumRelocations() const {
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uint32_t count = 0;
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for (const InputSection *inputSect : inputSections)
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count += inputSect->getNumRelocations();
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return count;
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}
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void CustomSection::writeRelocations(raw_ostream &os) const {
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for (const InputSection *s : inputSections)
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s->writeRelocations(os);
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}
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} // namespace wasm
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} // namespace lld
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