commit fef8de66a6ad56d71eb8bf8a401f8cdc82dea225
author Thomas Lively <tlively@google.com> Fri Apr 12 22:27:48 2019 +0000
committer Thomas Lively <tlively@google.com> Fri Apr 12 22:27:48 2019 +0000
tree 55b9ddd2be0fc7c1ac1ef4b1683aa44bee339bc8
parent bdb5e4e4ca5fbc7ef528067b65dda298e191e059

[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

llvm/tools/llvm-readobj/WasmDumper.cpp

diff --git a/llvm/tools/llvm-readobj/WasmDumper.cpp b/llvm/tools/llvm-readobj/WasmDumper.cpp
index edcd073..e232d112 100644
--- a/llvm/tools/llvm-readobj/WasmDumper.cpp
+++ b/llvm/tools/llvm-readobj/WasmDumper.cpp
@@ -32,11 +32,11 @@
 static const EnumEntry<uint32_t> WasmSectionTypes[] = {
 #define ENUM_ENTRY(X)                                                          \
   { #X, wasm::WASM_SEC_##X }
-    ENUM_ENTRY(CUSTOM),   ENUM_ENTRY(TYPE),  ENUM_ENTRY(IMPORT),
-    ENUM_ENTRY(FUNCTION), ENUM_ENTRY(TABLE), ENUM_ENTRY(MEMORY),
-    ENUM_ENTRY(GLOBAL),   ENUM_ENTRY(EVENT), ENUM_ENTRY(EXPORT),
-    ENUM_ENTRY(START),    ENUM_ENTRY(ELEM),  ENUM_ENTRY(CODE),
-    ENUM_ENTRY(DATA),
+    ENUM_ENTRY(CUSTOM),   ENUM_ENTRY(TYPE),      ENUM_ENTRY(IMPORT),
+    ENUM_ENTRY(FUNCTION), ENUM_ENTRY(TABLE),     ENUM_ENTRY(MEMORY),
+    ENUM_ENTRY(GLOBAL),   ENUM_ENTRY(EVENT),     ENUM_ENTRY(EXPORT),
+    ENUM_ENTRY(START),    ENUM_ENTRY(ELEM),      ENUM_ENTRY(CODE),
+    ENUM_ENTRY(DATA),     ENUM_ENTRY(DATACOUNT),
 #undef ENUM_ENTRY
 };
 

llvm/tools/obj2yaml/wasm2yaml.cpp

diff --git a/llvm/tools/obj2yaml/wasm2yaml.cpp b/llvm/tools/obj2yaml/wasm2yaml.cpp
index eacbe62..47d984b 100644
--- a/llvm/tools/obj2yaml/wasm2yaml.cpp
+++ b/llvm/tools/obj2yaml/wasm2yaml.cpp
@@ -353,6 +353,12 @@
       S = std::move(DataSec);
       break;
     }
+    case wasm::WASM_SEC_DATACOUNT: {
+      auto DataCountSec = make_unique<WasmYAML::DataCountSection>();
+      DataCountSec->Count = Obj.dataSegments().size();
+      S = std::move(DataCountSec);
+      break;
+    }
     default:
       llvm_unreachable("Unknown section type");
       break;

llvm/tools/yaml2obj/yaml2wasm.cpp

diff --git a/llvm/tools/yaml2obj/yaml2wasm.cpp b/llvm/tools/yaml2obj/yaml2wasm.cpp
index 322ac01..cd07a30 100644
--- a/llvm/tools/yaml2obj/yaml2wasm.cpp
+++ b/llvm/tools/yaml2obj/yaml2wasm.cpp
@@ -43,6 +43,7 @@
   int writeSectionContent(raw_ostream &OS, WasmYAML::ElemSection &Section);
   int writeSectionContent(raw_ostream &OS, WasmYAML::CodeSection &Section);
   int writeSectionContent(raw_ostream &OS, WasmYAML::DataSection &Section);
+  int writeSectionContent(raw_ostream &OS, WasmYAML::DataCountSection &Section);
 
   // Custom section types
   int writeSectionContent(raw_ostream &OS, WasmYAML::DylinkSection &Section);
@@ -514,6 +515,12 @@
   return 0;
 }
 
+int WasmWriter::writeSectionContent(raw_ostream &OS,
+                                    WasmYAML::DataCountSection &Section) {
+  encodeULEB128(Section.Count, OS);
+  return 0;
+}
+
 int WasmWriter::writeRelocSection(raw_ostream &OS, WasmYAML::Section &Sec,
                                   uint32_t SectionIndex) {
   switch (Sec.Type) {
@@ -614,6 +621,9 @@
     } else if (auto S = dyn_cast<WasmYAML::DataSection>(Sec.get())) {
       if (auto Err = writeSectionContent(StringStream, *S))
         return Err;
+    } else if (auto S = dyn_cast<WasmYAML::DataCountSection>(Sec.get())) {
+      if (auto Err = writeSectionContent(StringStream, *S))
+        return Err;
     } else {
       errs() << "Unknown section type: " << Sec->Type << "\n";
       return 1;