[WebAssembly] Add support for dylink section in object format

sbc100 · sbc100 · commit e4afbc68046c · 2018-11-14T18:36:24.000Z
See https://github.com/WebAssembly/tool-conventions/blob/master/DynamicLinking.md. Differential Revision: https://reviews.llvm.org/D54490 llvm-svn: 346880
diff --git a/llvm/include/llvm/BinaryFormat/Wasm.h b/llvm/include/llvm/BinaryFormat/Wasm.h
@@ -35,6 +35,13 @@ struct WasmObjectHeader {
   uint32_t Version;
 };
 
+struct WasmDylinkInfo {
+  uint32_t MemorySize; // Memory size in bytes
+  uint32_t MemoryAlignment;  // P2 alignment of memory
+  uint32_t TableSize;  // Table size in elements
+  uint32_t TableAlignment;  // P2 alignment of table
+};
+
 struct WasmExport {
   StringRef Name;
   uint8_t Kind;
diff --git a/llvm/include/llvm/Object/Wasm.h b/llvm/include/llvm/Object/Wasm.h
@@ -129,6 +129,7 @@ class WasmObjectFile : public ObjectFile {
 
   static bool classof(const Binary *v) { return v->isWasm(); }
 
+  const wasm::WasmDylinkInfo &dylinkInfo() const { return DylinkInfo; }
   ArrayRef<wasm::WasmSignature> types() const { return Signatures; }
   ArrayRef<uint32_t> functionTypes() const { return FunctionTypes; }
   ArrayRef<wasm::WasmImport> imports() const { return Imports; }
@@ -245,6 +246,7 @@ class WasmObjectFile : public ObjectFile {
   Error parseDataSection(ReadContext &Ctx);
 
   // Custom section types
+  Error parseDylinkSection(ReadContext &Ctx);
   Error parseNameSection(ReadContext &Ctx);
   Error parseLinkingSection(ReadContext &Ctx);
   Error parseLinkingSectionSymtab(ReadContext &Ctx);
@@ -253,6 +255,7 @@ class WasmObjectFile : public ObjectFile {
 
   wasm::WasmObjectHeader Header;
   std::vector<WasmSection> Sections;
+  wasm::WasmDylinkInfo DylinkInfo;
   std::vector<wasm::WasmSignature> Signatures;
   std::vector<uint32_t> FunctionTypes;
   std::vector<wasm::WasmTable> Tables;
diff --git a/llvm/include/llvm/ObjectYAML/WasmYAML.h b/llvm/include/llvm/ObjectYAML/WasmYAML.h
@@ -183,6 +183,20 @@ struct CustomSection : Section {
   yaml::BinaryRef Payload;
 };
 
+struct DylinkSection : CustomSection {
+  DylinkSection() : CustomSection("dylink") {}
+
+  static bool classof(const Section *S) {
+    auto C = dyn_cast<CustomSection>(S);
+    return C && C->Name == "dylink";
+  }
+
+  uint32_t MemorySize;
+  uint32_t MemoryAlignment;
+  uint32_t TableSize;
+  uint32_t TableAlignment;
+};
+
 struct NameSection : CustomSection {
   NameSection() : CustomSection("name") {}
 
diff --git a/llvm/lib/Object/WasmObjectFile.cpp b/llvm/lib/Object/WasmObjectFile.cpp
@@ -313,6 +313,18 @@ Error WasmObjectFile::parseSection(WasmSection &Sec) {
   }
 }
 
+Error WasmObjectFile::parseDylinkSection(ReadContext &Ctx) {
+  // See https://github.com/WebAssembly/tool-conventions/blob/master/DynamicLinking.md
+  DylinkInfo.MemorySize = readVaruint32(Ctx);
+  DylinkInfo.MemoryAlignment = readVaruint32(Ctx);
+  DylinkInfo.TableSize = readVaruint32(Ctx);
+  DylinkInfo.TableAlignment = readVaruint32(Ctx);
+  if (Ctx.Ptr != Ctx.End)
+    return make_error<GenericBinaryError>("dylink section ended prematurely",
+                                          object_error::parse_failed);
+  return Error::success();
+}
+
 Error WasmObjectFile::parseNameSection(ReadContext &Ctx) {
   llvm::DenseSet<uint64_t> Seen;
   if (Functions.size() != FunctionTypes.size()) {
@@ -721,7 +733,10 @@ Error WasmObjectFile::parseRelocSection(StringRef Name, ReadContext &Ctx) {
 }
 
 Error WasmObjectFile::parseCustomSection(WasmSection &Sec, ReadContext &Ctx) {
-  if (Sec.Name == "name") {
+  if (Sec.Name == "dylink") {
+    if (Error Err = parseDylinkSection(Ctx))
+      return Err;
+  } else if (Sec.Name == "name") {
     if (Error Err = parseNameSection(Ctx))
       return Err;
   } else if (Sec.Name == "linking") {
diff --git a/llvm/lib/ObjectYAML/WasmYAML.cpp b/llvm/lib/ObjectYAML/WasmYAML.cpp
@@ -48,6 +48,15 @@ static void commonSectionMapping(IO &IO, WasmYAML::Section &Section) {
   IO.mapOptional("Relocations", Section.Relocations);
 }
 
+static void sectionMapping(IO &IO, WasmYAML::DylinkSection &Section) {
+  commonSectionMapping(IO, Section);
+  IO.mapRequired("Name", Section.Name);
+  IO.mapRequired("MemorySize", Section.MemorySize);
+  IO.mapRequired("MemoryAlignment", Section.MemoryAlignment);
+  IO.mapRequired("TableSize", Section.TableSize);
+  IO.mapRequired("TableAlignment", Section.TableAlignment);
+}
+
 static void sectionMapping(IO &IO, WasmYAML::NameSection &Section) {
   commonSectionMapping(IO, Section);
   IO.mapRequired("Name", Section.Name);
@@ -147,7 +156,11 @@ void MappingTraits<std::unique_ptr<WasmYAML::Section>>::mapping(
     } else {
       IO.mapRequired("Name", SectionName);
     }
-    if (SectionName == "linking") {
+    if (SectionName == "dylink") {
+      if (!IO.outputting())
+        Section.reset(new WasmYAML::DylinkSection());
+      sectionMapping(IO, *cast<WasmYAML::DylinkSection>(Section.get()));
+    } else if (SectionName == "linking") {
       if (!IO.outputting())
         Section.reset(new WasmYAML::LinkingSection());
       sectionMapping(IO, *cast<WasmYAML::LinkingSection>(Section.get()));
diff --git a/llvm/test/ObjectYAML/wasm/dylink_section.yaml b/llvm/test/ObjectYAML/wasm/dylink_section.yaml
@@ -0,0 +1,24 @@
+# RUN: yaml2obj %s | obj2yaml | FileCheck %s
+--- !WASM
+FileHeader:
+  Version:         0x00000001
+
+Sections:
+  - Type:            CUSTOM
+    Name:            dylink
+    MemorySize:      4
+    MemoryAlignment: 2
+    TableSize:       1
+    TableAlignment:  0
+...
+# CHECK: --- !WASM
+# CHECK: FileHeader:
+# CHECK:   Version:           0x00000001
+# CHECK: Sections:
+# CHECK:   - Type:            CUSTOM
+# CHECK:     Name:            dylink
+# CHECK:     MemorySize:      4
+# CHECK:     MemoryAlignment: 2
+# CHECK:     TableSize:       1
+# CHECK:     TableAlignment:  0
+# CHECK: ...
diff --git a/llvm/tools/obj2yaml/wasm2yaml.cpp b/llvm/tools/obj2yaml/wasm2yaml.cpp
@@ -52,7 +52,16 @@ static WasmYAML::Limits make_limits(const wasm::WasmLimits &Limits) {
 std::unique_ptr<WasmYAML::CustomSection>
 WasmDumper::dumpCustomSection(const WasmSection &WasmSec) {
   std::unique_ptr<WasmYAML::CustomSection> CustomSec;
-  if (WasmSec.Name == "name") {
+  if (WasmSec.Name == "dylink") {
+    std::unique_ptr<WasmYAML::DylinkSection> DylinkSec =
+        make_unique<WasmYAML::DylinkSection>();
+    const wasm::WasmDylinkInfo& Info = Obj.dylinkInfo();
+    DylinkSec->MemorySize = Info.MemorySize;
+    DylinkSec->MemoryAlignment = Info.MemoryAlignment;
+    DylinkSec->TableSize = Info.TableSize;
+    DylinkSec->TableAlignment = Info.TableAlignment;
+    CustomSec = std::move(DylinkSec);
+  } else if (WasmSec.Name == "name") {
     std::unique_ptr<WasmYAML::NameSection> NameSec =
         make_unique<WasmYAML::NameSection>();
     for (const llvm::wasm::WasmFunctionName &Func : Obj.debugNames()) {
diff --git a/llvm/tools/yaml2obj/yaml2wasm.cpp b/llvm/tools/yaml2obj/yaml2wasm.cpp
@@ -45,6 +45,7 @@ class WasmWriter {
   int writeSectionContent(raw_ostream &OS, WasmYAML::DataSection &Section);
 
   // Custom section types
+  int writeSectionContent(raw_ostream &OS, WasmYAML::DylinkSection &Section);
   int writeSectionContent(raw_ostream &OS, WasmYAML::NameSection &Section);
   int writeSectionContent(raw_ostream &OS, WasmYAML::LinkingSection &Section);
   WasmYAML::Object &Obj;
@@ -132,6 +133,16 @@ class SubSectionWriter {
   raw_ostream &GetStream() { return StringStream; }
 };
 
+int WasmWriter::writeSectionContent(raw_ostream &OS,
+                                    WasmYAML::DylinkSection &Section) {
+  writeStringRef(Section.Name, OS);
+  encodeULEB128(Section.MemorySize, OS);
+  encodeULEB128(Section.MemoryAlignment, OS);
+  encodeULEB128(Section.TableSize, OS);
+  encodeULEB128(Section.TableAlignment, OS);
+  return 0;
+}
+
 int WasmWriter::writeSectionContent(raw_ostream &OS,
                                     WasmYAML::LinkingSection &Section) {
   writeStringRef(Section.Name, OS);
@@ -241,7 +252,10 @@ int WasmWriter::writeSectionContent(raw_ostream &OS,
 
 int WasmWriter::writeSectionContent(raw_ostream &OS,
                                     WasmYAML::CustomSection &Section) {
-  if (auto S = dyn_cast<WasmYAML::NameSection>(&Section)) {
+  if (auto S = dyn_cast<WasmYAML::DylinkSection>(&Section)) {
+    if (auto Err = writeSectionContent(OS, *S))
+      return Err;
+  } else if (auto S = dyn_cast<WasmYAML::NameSection>(&Section)) {
     if (auto Err = writeSectionContent(OS, *S))
       return Err;
   } else if (auto S = dyn_cast<WasmYAML::LinkingSection>(&Section)) {
