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[WebAssembly] Do not use inheritance to define SubSection.

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SubSection inherited from SyntheticSection, and SyntheticSection inherits
from OutputSection, so SubSection was an OutputSection. But that's wrong
because SubSection is not actually a WebAssembly output section.
It shares some functionalities with OutputSection, but overall it's very
different.

This patch removes that inheritance.

Differential Revision: https://reviews.llvm.org/D43719

llvm-svn: 326286
This commit is contained in:
Rui Ueyama
2018-02-28 00:52:42 +00:00
parent 4b56adce20
commit 4a1b2bbc88
3 changed files with 58 additions and 60 deletions
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5
lld/wasm/OutputSections.cpp
View File

@@ -11,6 +11,7 @@
#include "InputChunks.h"
#include "InputFiles.h"
#include "OutputSegment.h"
#include "WriterUtils.h"
#include "lld/Common/ErrorHandler.h"
#include "lld/Common/Threads.h"
#include "llvm/ADT/Twine.h"
@@ -65,10 +66,6 @@ std::string OutputSection::getSectionName() const {
return sectionTypeToString(Type);
}
std::string SubSection::getSectionName() const {
return std::string("subsection <type=") + std::to_string(Type) + ">";
}
void OutputSection::createHeader(size_t BodySize) {
raw_string_ostream OS(Header);
debugWrite(OS.tell(), "section type [" + Twine(getSectionName()) + "]");

16
lld/wasm/OutputSections.h
View File

@@ -85,22 +85,6 @@ protected:
raw_string_ostream BodyOutputStream;
};
// Some synthetic sections (e.g. "name" and "linking") have subsections.
// Just like the synthetic sections themselves these need to be created before
// they can be written out (since they are preceded by their length). This
// class is used to create subsections and then write them into the stream
// of the parent section.
class SubSection : public SyntheticSection {
public:
explicit SubSection(uint32_t Type) : SyntheticSection(Type) {}
std::string getSectionName() const;
void writeToStream(raw_ostream &OS) {
OS.write(Header.data(), Header.size());
OS.write(Body.data(), Body.size());
}
};
class CodeSection : public OutputSection {
public:
explicit CodeSection(ArrayRef<InputFunction *> Functions);

97
lld/wasm/Writer.cpp
View File

@@ -384,6 +384,30 @@ static uint32_t getWasmFlags(const Symbol *Sym) {
return Flags;
}
// Some synthetic sections (e.g. "name" and "linking") have subsections.
// Just like the synthetic sections themselves these need to be created before
// they can be written out (since they are preceded by their length). This
// class is used to create subsections and then write them into the stream
// of the parent section.
class SubSection {
public:
explicit SubSection(uint32_t Type) : Type(Type) {}
void writeTo(raw_ostream &To) {
OS.flush();
lld::wasm::writeUleb128(To, Type, "subsection type");
lld::wasm::writeUleb128(To, Body.size(), "subsection size");
To.write(Body.data(), Body.size());
}
private:
uint32_t Type;
std::string Body;
public:
raw_string_ostream OS{Body};
};
// Create the custom "linking" section containing linker metadata.
// This is only created when relocatable output is requested.
void Writer::createLinkingSection() {
@@ -396,61 +420,57 @@ void Writer::createLinkingSection() {
if (!SymtabEntries.empty()) {
SubSection Sub(WASM_SYMBOL_TABLE);
writeUleb128(Sub.getStream(), SymtabEntries.size(), "num symbols");
writeUleb128(Sub.OS, SymtabEntries.size(), "num symbols");
for (const Symbol *Sym : SymtabEntries) {
assert(Sym->isDefined() || Sym->isUndefined());
WasmSymbolType Kind = Sym->getWasmType();
uint32_t Flags = getWasmFlags(Sym);
writeUleb128(Sub.getStream(), Kind, "sym kind");
writeUleb128(Sub.getStream(), Flags, "sym flags");
writeUleb128(Sub.OS, Kind, "sym kind");
writeUleb128(Sub.OS, Flags, "sym flags");
switch (Kind) {
case llvm::wasm::WASM_SYMBOL_TYPE_FUNCTION:
case llvm::wasm::WASM_SYMBOL_TYPE_GLOBAL:
writeUleb128(Sub.getStream(), Sym->getOutputIndex(), "index");
writeUleb128(Sub.OS, Sym->getOutputIndex(), "index");
if (Sym->isDefined())
writeStr(Sub.getStream(), Sym->getName(), "sym name");
writeStr(Sub.OS, Sym->getName(), "sym name");
break;
case llvm::wasm::WASM_SYMBOL_TYPE_DATA:
writeStr(Sub.getStream(), Sym->getName(), "sym name");
writeStr(Sub.OS, Sym->getName(), "sym name");
if (auto *DataSym = dyn_cast<DefinedData>(Sym)) {
writeUleb128(Sub.getStream(), DataSym->getOutputSegmentIndex(),
"index");
writeUleb128(Sub.getStream(), DataSym->getOutputSegmentOffset(),
writeUleb128(Sub.OS, DataSym->getOutputSegmentIndex(), "index");
writeUleb128(Sub.OS, DataSym->getOutputSegmentOffset(),
"data offset");
writeUleb128(Sub.getStream(), DataSym->getSize(), "data size");
writeUleb128(Sub.OS, DataSym->getSize(), "data size");
}
break;
}
}
Sub.finalizeContents();
Sub.writeToStream(OS);
Sub.writeTo(OS);
}
if (Segments.size()) {
SubSection Sub(WASM_SEGMENT_INFO);
writeUleb128(Sub.getStream(), Segments.size(), "num data segments");
writeUleb128(Sub.OS, Segments.size(), "num data segments");
for (const OutputSegment *S : Segments) {
writeStr(Sub.getStream(), S->Name, "segment name");
writeUleb128(Sub.getStream(), S->Alignment, "alignment");
writeUleb128(Sub.getStream(), 0, "flags");
writeStr(Sub.OS, S->Name, "segment name");
writeUleb128(Sub.OS, S->Alignment, "alignment");
writeUleb128(Sub.OS, 0, "flags");
}
Sub.finalizeContents();
Sub.writeToStream(OS);
Sub.writeTo(OS);
}
if (!InitFunctions.empty()) {
SubSection Sub(WASM_INIT_FUNCS);
writeUleb128(Sub.getStream(), InitFunctions.size(), "num init functions");
writeUleb128(Sub.OS, InitFunctions.size(), "num init functions");
for (const WasmInitEntry &F : InitFunctions) {
writeUleb128(Sub.getStream(), F.Priority, "priority");
writeUleb128(Sub.getStream(), F.Sym->getOutputSymbolIndex(),
"function index");
writeUleb128(Sub.OS, F.Priority, "priority");
writeUleb128(Sub.OS, F.Sym->getOutputSymbolIndex(), "function index");
}
Sub.finalizeContents();
Sub.writeToStream(OS);
Sub.writeTo(OS);
}
struct ComdatEntry { unsigned Kind; uint32_t Index; };
@@ -477,18 +497,17 @@ void Writer::createLinkingSection() {
if (!Comdats.empty()) {
SubSection Sub(WASM_COMDAT_INFO);
writeUleb128(Sub.getStream(), Comdats.size(), "num comdats");
writeUleb128(Sub.OS, Comdats.size(), "num comdats");
for (const auto &C : Comdats) {
writeStr(Sub.getStream(), C.first, "comdat name");
writeUleb128(Sub.getStream(), 0, "comdat flags"); // flags for future use
writeUleb128(Sub.getStream(), C.second.size(), "num entries");
writeStr(Sub.OS, C.first, "comdat name");
writeUleb128(Sub.OS, 0, "comdat flags"); // flags for future use
writeUleb128(Sub.OS, C.second.size(), "num entries");
for (const ComdatEntry &Entry : C.second) {
writeUleb128(Sub.getStream(), Entry.Kind, "entry kind");
writeUleb128(Sub.getStream(), Entry.Index, "entry index");
writeUleb128(Sub.OS, Entry.Kind, "entry kind");
writeUleb128(Sub.OS, Entry.Index, "entry index");
}
}
Sub.finalizeContents();
Sub.writeToStream(OS);
Sub.writeTo(OS);
}
}
@@ -505,8 +524,7 @@ void Writer::createNameSection() {
SyntheticSection *Section = createSyntheticSection(WASM_SEC_CUSTOM, "name");
SubSection Sub(WASM_NAMES_FUNCTION);
raw_ostream &OS = Sub.getStream();
writeUleb128(OS, NumNames, "name count");
writeUleb128(Sub.OS, NumNames, "name count");
// Names must appear in function index order. As it happens ImportedSymbols
// and InputFunctions are numbered in order with imported functions coming
@@ -514,18 +532,17 @@ void Writer::createNameSection() {
for (const Symbol *S : ImportedSymbols) {
if (!isa<FunctionSymbol>(S))
continue;
writeUleb128(OS, S->getOutputIndex(), "import index");
writeStr(OS, S->getName(), "symbol name");
writeUleb128(Sub.OS, S->getOutputIndex(), "import index");
writeStr(Sub.OS, S->getName(), "symbol name");
}
for (const InputFunction *F : InputFunctions) {
if (!F->getName().empty()) {
writeUleb128(OS, F->getOutputIndex(), "func index");
writeStr(OS, F->getName(), "symbol name");
writeUleb128(Sub.OS, F->getOutputIndex(), "func index");
writeStr(Sub.OS, F->getName(), "symbol name");
}
}
Sub.finalizeContents();
Sub.writeToStream(Section->getStream());
Sub.writeTo(Section->getStream());
}
void Writer::writeHeader() {