[WebAssembly] Add support for weak symbols in the binary format

This also introduces the updated format for the
"linking" section which can represent extra
symbol information.  See:
https://github.com/WebAssembly/tool-conventions/pull/10

Differential Revision: https://reviews.llvm.org/D34019

llvm-svn: 305769

1 files changed, 41 insertions, 9 deletions

diff --git a/llvm/lib/ObjectYAML/WasmYAML.cpp b/llvm/lib/ObjectYAML/WasmYAML.cpp
index 353d027f4e1..65703c6cf68 100644
--- a/llvm/lib/ObjectYAML/WasmYAML.cpp
+++ b/llvm/lib/ObjectYAML/WasmYAML.cpp
@@ -47,14 +47,22 @@ static void commonSectionMapping(IO &IO, WasmYAML::Section &Section) {
   IO.mapOptional("Relocations", Section.Relocations);
 }
 
+static void sectionMapping(IO &IO, WasmYAML::NameSection &Section) {
+  commonSectionMapping(IO, Section);
+  IO.mapRequired("Name", Section.Name);
+  IO.mapOptional("FunctionNames", Section.FunctionNames);
+}
+
+static void sectionMapping(IO &IO, WasmYAML::LinkingSection &Section) {
+  commonSectionMapping(IO, Section);
+  IO.mapRequired("Name", Section.Name);
+  IO.mapRequired("SymbolInfo", Section.SymbolInfos);
+}
+
 static void sectionMapping(IO &IO, WasmYAML::CustomSection &Section) {
   commonSectionMapping(IO, Section);
   IO.mapRequired("Name", Section.Name);
-  if (Section.Name == "name") {
-    IO.mapOptional("FunctionNames", Section.FunctionNames);
-  } else {
-    IO.mapRequired("Payload", Section.Payload);
-  }
+  IO.mapRequired("Payload", Section.Payload);
 }
 
 static void sectionMapping(IO &IO, WasmYAML::TypeSection &Section) {
@@ -121,11 +129,29 @@ void MappingTraits<std::unique_ptr<WasmYAML::Section>>::mapping(
     IO.mapRequired("Type", SectionType);
 
   switch (SectionType) {
-  case wasm::WASM_SEC_CUSTOM:
-    if (!IO.outputting())
-      Section.reset(new WasmYAML::CustomSection());
-    sectionMapping(IO, *cast<WasmYAML::CustomSection>(Section.get()));
+  case wasm::WASM_SEC_CUSTOM: {
+    StringRef SectionName;
+    if (IO.outputting()) {
+      auto CustomSection = cast<WasmYAML::CustomSection>(Section.get());
+      SectionName = CustomSection->Name;
+    } else {
+      IO.mapRequired("Name", SectionName);
+    }
+    if (SectionName == "linking") {
+      if (!IO.outputting())
+        Section.reset(new WasmYAML::LinkingSection());
+      sectionMapping(IO, *cast<WasmYAML::LinkingSection>(Section.get()));
+    } else if (SectionName == "name") {
+      if (!IO.outputting())
+        Section.reset(new WasmYAML::NameSection());
+      sectionMapping(IO, *cast<WasmYAML::NameSection>(Section.get()));
+    } else {
+      if (!IO.outputting())
+        Section.reset(new WasmYAML::CustomSection(SectionName));
+      sectionMapping(IO, *cast<WasmYAML::CustomSection>(Section.get()));
+    }
     break;
+  }
   case wasm::WASM_SEC_TYPE:
     if (!IO.outputting())
       Section.reset(new WasmYAML::TypeSection());
@@ -321,6 +347,12 @@ void MappingTraits<WasmYAML::DataSegment>::mapping(
   IO.mapRequired("Content", Segment.Content);
 }
 
+void MappingTraits<WasmYAML::SymbolInfo>::mapping(IO &IO,
+                                                  WasmYAML::SymbolInfo &Info) {
+  IO.mapRequired("Name", Info.Name);
+  IO.mapRequired("Flags", Info.Flags);
+}
+
 void ScalarEnumerationTraits<WasmYAML::ValueType>::enumeration(
     IO &IO, WasmYAML::ValueType &Type) {
 #define ECase(X) IO.enumCase(Type, #X, wasm::WASM_TYPE_##X);