[WebAssembly] Make tag attribute's encoding uint8

This changes the encoding of the `attribute` field, which currently only
contains the value `0` denoting this tag is for an exception, from
`varuint32` to `uint8`. This field is effectively unused at the moment
and reserved for future use, and it is not likely to need `varuint32`
even in future.
See https://github.com/WebAssembly/exception-handling/pull/162.

This does not change any encoded binaries because `0` is encoded in the
same way both in `varuint32` and `uint8`.

Reviewed By: tlively

Differential Revision: https://reviews.llvm.org/D104571

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/Object/WasmObjectFile.cpp b/llvm/lib/Object/WasmObjectFile.cpp
index 0f4eaa1..5188037 100644
--- a/llvm/lib/Object/WasmObjectFile.cpp
+++ b/llvm/lib/Object/WasmObjectFile.cpp
@@ -1066,7 +1066,7 @@ Error WasmObjectFile::parseImportSection(ReadContext &Ctx) {
     }
     case wasm::WASM_EXTERNAL_TAG:
       NumImportedTags++;
-      Im.Tag.Attribute = readVarint32(Ctx);
+      Im.Tag.Attribute = readUint8(Ctx);
       Im.Tag.SigIndex = readVarint32(Ctx);
       break;
     default:
@@ -1143,7 +1143,7 @@ Error WasmObjectFile::parseTagSection(ReadContext &Ctx) {
   while (Count--) {
     wasm::WasmTag Tag;
     Tag.Index = NumImportedTags + Tags.size();
-    Tag.Type.Attribute = readVaruint32(Ctx);
+    Tag.Type.Attribute = readUint8(Ctx);
     Tag.Type.SigIndex = readVaruint32(Ctx);
     Tags.push_back(Tag);
   }