wasm/OutputSections.cpp - llvm-project/lld - Git at Google

 //===- OutputSections.cpp -------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//

 #include "OutputSections.h"
 #include "InputChunks.h"
 #include "InputFiles.h"
 #include "OutputSegment.h"
 #include "WriterUtils.h"
 #include "lld/Common/ErrorHandler.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/LEB128.h"
 #include "llvm/Support/Parallel.h"

 #define DEBUG_TYPE "lld"

 using namespace llvm;
 using namespace llvm::wasm;

 namespace lld {

 // Returns a string, e.g. "FUNCTION(.text)".
 std::string toString(const wasm::OutputSection &sec) {
   if (!sec.name.empty())
     return (sec.getSectionName() + "(" + sec.name + ")").str();
   return std::string(sec.getSectionName());
 }

 namespace wasm {
 static StringRef sectionTypeToString(uint32_t sectionType) {
   switch (sectionType) {
   case WASM_SEC_CUSTOM:
     return "CUSTOM";
   case WASM_SEC_TYPE:
     return "TYPE";
   case WASM_SEC_IMPORT:
     return "IMPORT";
   case WASM_SEC_FUNCTION:
     return "FUNCTION";
   case WASM_SEC_TABLE:
     return "TABLE";
   case WASM_SEC_MEMORY:
     return "MEMORY";
   case WASM_SEC_GLOBAL:
     return "GLOBAL";
   case WASM_SEC_EVENT:
     return "EVENT";
   case WASM_SEC_EXPORT:
     return "EXPORT";
   case WASM_SEC_START:
     return "START";
   case WASM_SEC_ELEM:
     return "ELEM";
   case WASM_SEC_CODE:
     return "CODE";
   case WASM_SEC_DATA:
     return "DATA";
   case WASM_SEC_DATACOUNT:
     return "DATACOUNT";
   default:
     fatal("invalid section type");
   }
 }

 StringRef OutputSection::getSectionName() const {
   return sectionTypeToString(type);
 }

 void OutputSection::createHeader(size_t bodySize) {
   raw_string_ostream os(header);
   debugWrite(os.tell(), "section type [" + getSectionName() + "]");
   encodeULEB128(type, os);
   writeUleb128(os, bodySize, "section size");
   os.flush();
   log("createHeader: " + toString(*this) + " body=" + Twine(bodySize) +
       " total=" + Twine(getSize()));
 }

 void CodeSection::finalizeContents() {
   raw_string_ostream os(codeSectionHeader);
   writeUleb128(os, functions.size(), "function count");
   os.flush();
   bodySize = codeSectionHeader.size();

   for (InputFunction *func : functions) {
     func->outputSec = this;
     func->outSecOff = bodySize;
     func->calculateSize();
     // All functions should have a non-empty body at this point
     assert(func->getSize());
     bodySize += func->getSize();
   }

   createHeader(bodySize);
 }

 void CodeSection::writeTo(uint8_t *buf) {
   log("writing " + toString(*this));
   log(" size=" + Twine(getSize()));
   log(" headersize=" + Twine(header.size()));
   log(" codeheadersize=" + Twine(codeSectionHeader.size()));
   buf += offset;

   // Write section header
   memcpy(buf, header.data(), header.size());
   buf += header.size();

   // Write code section headers
   memcpy(buf, codeSectionHeader.data(), codeSectionHeader.size());

   // Write code section bodies
   for (const InputChunk *chunk : functions)
     chunk->writeTo(buf);
 }

 uint32_t CodeSection::getNumRelocations() const {
   uint32_t count = 0;
   for (const InputChunk *func : functions)
     count += func->getNumRelocations();
   return count;
 }

 void CodeSection::writeRelocations(raw_ostream &os) const {
   for (const InputChunk *c : functions)
     c->writeRelocations(os);
 }

 void DataSection::finalizeContents() {
   raw_string_ostream os(dataSectionHeader);
   unsigned segmentCount =
       std::count_if(segments.begin(), segments.end(),
                     [](OutputSegment *segment) { return !segment->isBss; });

 #ifndef NDEBUG
   unsigned activeCount = std::count_if(
       segments.begin(), segments.end(), [](OutputSegment *segment) {
         return (segment->initFlags & WASM_DATA_SEGMENT_IS_PASSIVE) == 0;
       });
 #endif

   assert((!config->isPic || activeCount <= 1) &&
          "Currenly only a single data segment is supported in PIC mode");

   writeUleb128(os, segmentCount, "data segment count");
   os.flush();
   bodySize = dataSectionHeader.size();

   for (OutputSegment *segment : segments) {
     if (segment->isBss)
       continue;
     raw_string_ostream os(segment->header);
     writeUleb128(os, segment->initFlags, "init flags");
     if (segment->initFlags & WASM_DATA_SEGMENT_HAS_MEMINDEX)
       writeUleb128(os, 0, "memory index");
     if ((segment->initFlags & WASM_DATA_SEGMENT_IS_PASSIVE) == 0) {
       WasmInitExpr initExpr;
       if (config->isPic) {
         initExpr.Opcode = WASM_OPCODE_GLOBAL_GET;
         initExpr.Value.Global = WasmSym::memoryBase->getGlobalIndex();
       } else if (config->is64.getValueOr(false)) {
         initExpr.Opcode = WASM_OPCODE_I64_CONST;
         initExpr.Value.Int64 = static_cast<int64_t>(segment->startVA);
       } else {
         initExpr.Opcode = WASM_OPCODE_I32_CONST;
         initExpr.Value.Int32 = static_cast<int32_t>(segment->startVA);
       }
       writeInitExpr(os, initExpr);
     }
     writeUleb128(os, segment->size, "segment size");
     os.flush();

     segment->sectionOffset = bodySize;
     bodySize += segment->header.size() + segment->size;
     log("Data segment: size=" + Twine(segment->size) + ", startVA=" +
         Twine::utohexstr(segment->startVA) + ", name=" + segment->name);

     for (InputSegment *inputSeg : segment->inputSegments) {
       inputSeg->outputSec = this;
       inputSeg->outSecOff = segment->sectionOffset + segment->header.size() +
                             inputSeg->outputSegmentOffset;
     }
   }

   createHeader(bodySize);
 }

 void DataSection::writeTo(uint8_t *buf) {
   log("writing " + toString(*this) + " size=" + Twine(getSize()) +
       " body=" + Twine(bodySize));
   buf += offset;

   // Write section header
   memcpy(buf, header.data(), header.size());
   buf += header.size();

   // Write data section headers
   memcpy(buf, dataSectionHeader.data(), dataSectionHeader.size());

   for (const OutputSegment *segment : segments) {
     if (segment->isBss)
       continue;
     // Write data segment header
     uint8_t *segStart = buf + segment->sectionOffset;
     memcpy(segStart, segment->header.data(), segment->header.size());

     // Write segment data payload
     for (const InputChunk *chunk : segment->inputSegments)
       chunk->writeTo(buf);
   }
 }

 uint32_t DataSection::getNumRelocations() const {
   uint32_t count = 0;
   for (const OutputSegment *seg : segments)
     for (const InputChunk *inputSeg : seg->inputSegments)
       count += inputSeg->getNumRelocations();
   return count;
 }

 void DataSection::writeRelocations(raw_ostream &os) const {
   for (const OutputSegment *seg : segments)
     for (const InputChunk *c : seg->inputSegments)
       c->writeRelocations(os);
 }

 bool DataSection::isNeeded() const {
   for (const OutputSegment *seg : segments)
     if (!seg->isBss)
       return true;
   return false;
 }

 void CustomSection::finalizeContents() {
   raw_string_ostream os(nameData);
   encodeULEB128(name.size(), os);
   os << name;
   os.flush();

   for (InputSection *section : inputSections) {
     assert(!section->discarded);
     section->outputSec = this;
     section->outSecOff = payloadSize;
     payloadSize += section->getSize();
   }

   createHeader(payloadSize + nameData.size());
 }

 void CustomSection::writeTo(uint8_t *buf) {
   log("writing " + toString(*this) + " size=" + Twine(getSize()) +
       " chunks=" + Twine(inputSections.size()));

   assert(offset);
   buf += offset;

   // Write section header
   memcpy(buf, header.data(), header.size());
   buf += header.size();
   memcpy(buf, nameData.data(), nameData.size());
   buf += nameData.size();

   // Write custom sections payload
   for (const InputSection *section : inputSections)
     section->writeTo(buf);
 }

 uint32_t CustomSection::getNumRelocations() const {
   uint32_t count = 0;
   for (const InputSection *inputSect : inputSections)
     count += inputSect->getNumRelocations();
   return count;
 }

 void CustomSection::writeRelocations(raw_ostream &os) const {
   for (const InputSection *s : inputSections)
     s->writeRelocations(os);
 }

 } // namespace wasm
 } // namespace lld
	//===- OutputSections.cpp -------------------------------------------------===//
	//
	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
	// See https://llvm.org/LICENSE.txt for license information.
	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
	//
	//===----------------------------------------------------------------------===//

	#include "OutputSections.h"
	#include "InputChunks.h"
	#include "InputFiles.h"
	#include "OutputSegment.h"
	#include "WriterUtils.h"
	#include "lld/Common/ErrorHandler.h"
	#include "llvm/ADT/Twine.h"
	#include "llvm/Support/LEB128.h"
	#include "llvm/Support/Parallel.h"

	#define DEBUG_TYPE "lld"

	using namespace llvm;
	using namespace llvm::wasm;

	namespace lld {

	// Returns a string, e.g. "FUNCTION(.text)".
	std::string toString(const wasm::OutputSection &sec) {
	if (!sec.name.empty())
	return (sec.getSectionName() + "(" + sec.name + ")").str();
	return std::string(sec.getSectionName());
	}

	namespace wasm {
	static StringRef sectionTypeToString(uint32_t sectionType) {
	switch (sectionType) {
	case WASM_SEC_CUSTOM:
	return "CUSTOM";
	case WASM_SEC_TYPE:
	return "TYPE";
	case WASM_SEC_IMPORT:
	return "IMPORT";
	case WASM_SEC_FUNCTION:
	return "FUNCTION";
	case WASM_SEC_TABLE:
	return "TABLE";
	case WASM_SEC_MEMORY:
	return "MEMORY";
	case WASM_SEC_GLOBAL:
	return "GLOBAL";
	case WASM_SEC_EVENT:
	return "EVENT";
	case WASM_SEC_EXPORT:
	return "EXPORT";
	case WASM_SEC_START:
	return "START";
	case WASM_SEC_ELEM:
	return "ELEM";
	case WASM_SEC_CODE:
	return "CODE";
	case WASM_SEC_DATA:
	return "DATA";
	case WASM_SEC_DATACOUNT:
	return "DATACOUNT";
	default:
	fatal("invalid section type");
	}
	}

	StringRef OutputSection::getSectionName() const {
	return sectionTypeToString(type);
	}

	void OutputSection::createHeader(size_t bodySize) {
	raw_string_ostream os(header);
	debugWrite(os.tell(), "section type [" + getSectionName() + "]");
	encodeULEB128(type, os);
	writeUleb128(os, bodySize, "section size");
	os.flush();
	log("createHeader: " + toString(*this) + " body=" + Twine(bodySize) +
	" total=" + Twine(getSize()));
	}

	void CodeSection::finalizeContents() {
	raw_string_ostream os(codeSectionHeader);
	writeUleb128(os, functions.size(), "function count");
	os.flush();
	bodySize = codeSectionHeader.size();

	for (InputFunction *func : functions) {
	func->outputSec = this;
	func->outSecOff = bodySize;
	func->calculateSize();
	// All functions should have a non-empty body at this point
	assert(func->getSize());
	bodySize += func->getSize();
	}

	createHeader(bodySize);
	}

	void CodeSection::writeTo(uint8_t *buf) {
	log("writing " + toString(*this));
	log(" size=" + Twine(getSize()));
	log(" headersize=" + Twine(header.size()));
	log(" codeheadersize=" + Twine(codeSectionHeader.size()));
	buf += offset;

	// Write section header
	memcpy(buf, header.data(), header.size());
	buf += header.size();

	// Write code section headers
	memcpy(buf, codeSectionHeader.data(), codeSectionHeader.size());

	// Write code section bodies
	for (const InputChunk *chunk : functions)
	chunk->writeTo(buf);
	}

	uint32_t CodeSection::getNumRelocations() const {
	uint32_t count = 0;
	for (const InputChunk *func : functions)
	count += func->getNumRelocations();
	return count;
	}

	void CodeSection::writeRelocations(raw_ostream &os) const {
	for (const InputChunk *c : functions)
	c->writeRelocations(os);
	}

	void DataSection::finalizeContents() {
	raw_string_ostream os(dataSectionHeader);
	unsigned segmentCount =
	std::count_if(segments.begin(), segments.end(),
	[](OutputSegment *segment) { return !segment->isBss; });

	#ifndef NDEBUG
	unsigned activeCount = std::count_if(
	segments.begin(), segments.end(), [](OutputSegment *segment) {
	return (segment->initFlags & WASM_DATA_SEGMENT_IS_PASSIVE) == 0;
	});
	#endif

	assert((!config->isPic \|\| activeCount <= 1) &&
	"Currenly only a single data segment is supported in PIC mode");

	writeUleb128(os, segmentCount, "data segment count");
	os.flush();
	bodySize = dataSectionHeader.size();

	for (OutputSegment *segment : segments) {
	if (segment->isBss)
	continue;
	raw_string_ostream os(segment->header);
	writeUleb128(os, segment->initFlags, "init flags");
	if (segment->initFlags & WASM_DATA_SEGMENT_HAS_MEMINDEX)
	writeUleb128(os, 0, "memory index");
	if ((segment->initFlags & WASM_DATA_SEGMENT_IS_PASSIVE) == 0) {
	WasmInitExpr initExpr;
	if (config->isPic) {
	initExpr.Opcode = WASM_OPCODE_GLOBAL_GET;
	initExpr.Value.Global = WasmSym::memoryBase->getGlobalIndex();
	} else if (config->is64.getValueOr(false)) {
	initExpr.Opcode = WASM_OPCODE_I64_CONST;
	initExpr.Value.Int64 = static_cast<int64_t>(segment->startVA);
	} else {
	initExpr.Opcode = WASM_OPCODE_I32_CONST;
	initExpr.Value.Int32 = static_cast<int32_t>(segment->startVA);
	}
	writeInitExpr(os, initExpr);
	}
	writeUleb128(os, segment->size, "segment size");
	os.flush();

	segment->sectionOffset = bodySize;
	bodySize += segment->header.size() + segment->size;
	log("Data segment: size=" + Twine(segment->size) + ", startVA=" +
	Twine::utohexstr(segment->startVA) + ", name=" + segment->name);

	for (InputSegment *inputSeg : segment->inputSegments) {
	inputSeg->outputSec = this;
	inputSeg->outSecOff = segment->sectionOffset + segment->header.size() +
	inputSeg->outputSegmentOffset;
	}
	}

	createHeader(bodySize);
	}

	void DataSection::writeTo(uint8_t *buf) {
	log("writing " + toString(*this) + " size=" + Twine(getSize()) +
	" body=" + Twine(bodySize));
	buf += offset;

	// Write section header
	memcpy(buf, header.data(), header.size());
	buf += header.size();

	// Write data section headers
	memcpy(buf, dataSectionHeader.data(), dataSectionHeader.size());

	for (const OutputSegment *segment : segments) {
	if (segment->isBss)
	continue;
	// Write data segment header
	uint8_t *segStart = buf + segment->sectionOffset;
	memcpy(segStart, segment->header.data(), segment->header.size());

	// Write segment data payload
	for (const InputChunk *chunk : segment->inputSegments)
	chunk->writeTo(buf);
	}
	}

	uint32_t DataSection::getNumRelocations() const {
	uint32_t count = 0;
	for (const OutputSegment *seg : segments)
	for (const InputChunk *inputSeg : seg->inputSegments)
	count += inputSeg->getNumRelocations();
	return count;
	}

	void DataSection::writeRelocations(raw_ostream &os) const {
	for (const OutputSegment *seg : segments)
	for (const InputChunk *c : seg->inputSegments)
	c->writeRelocations(os);
	}

	bool DataSection::isNeeded() const {
	for (const OutputSegment *seg : segments)
	if (!seg->isBss)
	return true;
	return false;
	}

	void CustomSection::finalizeContents() {
	raw_string_ostream os(nameData);
	encodeULEB128(name.size(), os);
	os << name;
	os.flush();

	for (InputSection *section : inputSections) {
	assert(!section->discarded);
	section->outputSec = this;
	section->outSecOff = payloadSize;
	payloadSize += section->getSize();
	}

	createHeader(payloadSize + nameData.size());
	}

	void CustomSection::writeTo(uint8_t *buf) {
	log("writing " + toString(*this) + " size=" + Twine(getSize()) +
	" chunks=" + Twine(inputSections.size()));

	assert(offset);
	buf += offset;

	// Write section header
	memcpy(buf, header.data(), header.size());
	buf += header.size();
	memcpy(buf, nameData.data(), nameData.size());
	buf += nameData.size();

	// Write custom sections payload
	for (const InputSection *section : inputSections)
	section->writeTo(buf);
	}

	uint32_t CustomSection::getNumRelocations() const {
	uint32_t count = 0;
	for (const InputSection *inputSect : inputSections)
	count += inputSect->getNumRelocations();
	return count;
	}

	void CustomSection::writeRelocations(raw_ostream &os) const {
	for (const InputSection *s : inputSections)
	s->writeRelocations(os);
	}

	} // namespace wasm
	} // namespace lld