[WebAssembly] Add DataCount section to object files
Summary:
This ensures that object files will continue to validate as
WebAssembly modules in the presence of bulk memory operations. Engines
that don't support bulk memory operations will not recognize the
DataCount section and will report validation errors, but that's ok
because object files aren't supposed to be run directly anyway.
Reviewers: aheejin, dschuff, sbc100
Subscribers: jgravelle-google, hiraditya, sunfish, rupprecht, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60623
llvm-svn: 358315
diff --git a/llvm/lib/MC/WasmObjectWriter.cpp b/llvm/lib/MC/WasmObjectWriter.cpp
index 6367709..2994772 100644
--- a/llvm/lib/MC/WasmObjectWriter.cpp
+++ b/llvm/lib/MC/WasmObjectWriter.cpp
@@ -326,6 +326,7 @@
void writeFunctionSection(ArrayRef<WasmFunction> Functions);
void writeExportSection(ArrayRef<wasm::WasmExport> Exports);
void writeElemSection(ArrayRef<uint32_t> TableElems);
+ void writeDataCountSection();
void writeCodeSection(const MCAssembler &Asm, const MCAsmLayout &Layout,
ArrayRef<WasmFunction> Functions);
void writeDataSection();
@@ -849,6 +850,16 @@
endSection(Section);
}
+void WasmObjectWriter::writeDataCountSection() {
+ if (DataSegments.empty())
+ return;
+
+ SectionBookkeeping Section;
+ startSection(Section, wasm::WASM_SEC_DATACOUNT);
+ encodeULEB128(DataSegments.size(), W.OS);
+ endSection(Section);
+}
+
void WasmObjectWriter::writeCodeSection(const MCAssembler &Asm,
const MCAsmLayout &Layout,
ArrayRef<WasmFunction> Functions) {
@@ -1600,6 +1611,7 @@
writeEventSection(Events);
writeExportSection(Exports);
writeElemSection(TableElems);
+ writeDataCountSection();
writeCodeSection(Asm, Layout, Functions);
writeDataSection();
for (auto &CustomSection : CustomSections)
diff --git a/llvm/lib/Object/WasmObjectFile.cpp b/llvm/lib/Object/WasmObjectFile.cpp
index 1664500..167b8c2 100644
--- a/llvm/lib/Object/WasmObjectFile.cpp
+++ b/llvm/lib/Object/WasmObjectFile.cpp
@@ -316,6 +316,8 @@
return parseCodeSection(Ctx);
case wasm::WASM_SEC_DATA:
return parseDataSection(Ctx);
+ case wasm::WASM_SEC_DATACOUNT:
+ return parseDataCountSection(Ctx);
default:
return make_error<GenericBinaryError>("Bad section type",
object_error::parse_failed);
@@ -1201,6 +1203,9 @@
Error WasmObjectFile::parseDataSection(ReadContext &Ctx) {
DataSection = Sections.size();
uint32_t Count = readVaruint32(Ctx);
+ if (DataCount && Count != DataCount.getValue())
+ return make_error<GenericBinaryError>(
+ "Number of data segments does not match DataCount section");
DataSegments.reserve(Count);
while (Count--) {
WasmSegment Segment;
@@ -1234,6 +1239,11 @@
return Error::success();
}
+Error WasmObjectFile::parseDataCountSection(ReadContext &Ctx) {
+ DataCount = readVaruint32(Ctx);
+ return Error::success();
+}
+
const wasm::WasmObjectHeader &WasmObjectFile::getHeader() const {
return Header;
}
@@ -1399,6 +1409,7 @@
ECase(ELEM);
ECase(CODE);
ECase(DATA);
+ ECase(DATACOUNT);
case wasm::WASM_SEC_CUSTOM:
Res = S.Name;
break;
diff --git a/llvm/lib/ObjectYAML/WasmYAML.cpp b/llvm/lib/ObjectYAML/WasmYAML.cpp
index 3841c5b..19c7f54 100644
--- a/llvm/lib/ObjectYAML/WasmYAML.cpp
+++ b/llvm/lib/ObjectYAML/WasmYAML.cpp
@@ -153,6 +153,11 @@
IO.mapRequired("Segments", Section.Segments);
}
+static void sectionMapping(IO &IO, WasmYAML::DataCountSection &Section) {
+ commonSectionMapping(IO, Section);
+ IO.mapRequired("Count", Section.Count);
+}
+
void MappingTraits<std::unique_ptr<WasmYAML::Section>>::mapping(
IO &IO, std::unique_ptr<WasmYAML::Section> &Section) {
WasmYAML::SectionType SectionType;
@@ -257,6 +262,11 @@
Section.reset(new WasmYAML::DataSection());
sectionMapping(IO, *cast<WasmYAML::DataSection>(Section.get()));
break;
+ case wasm::WASM_SEC_DATACOUNT:
+ if (!IO.outputting())
+ Section.reset(new WasmYAML::DataCountSection());
+ sectionMapping(IO, *cast<WasmYAML::DataCountSection>(Section.get()));
+ break;
default:
llvm_unreachable("Unknown section type");
}
@@ -278,6 +288,7 @@
ECase(ELEM);
ECase(CODE);
ECase(DATA);
+ ECase(DATACOUNT);
#undef ECase
}