Add initial support for code metadata (#1840)

See https://github.com/WebAssembly/tool-conventions/blob/main/CodeMetadata.md  for the specification.

In particular this pr implements the following:

- Parsing code metadata sections in BinaryReader, providing appropriate callbacks that a BinaryReaderDelegate can implement:
    - BinaryReaderObjdump: show the sections in a human-readable form
    - BinaryReaderIr: add code metadata in the IR as expressions
- Parsing code metadata annotations in text format, adding them in the IR like the BinaryReaderIR does
- Writing the code metadata present in the IR in the proper sections when converting IR to binary
- Support in wasm-decompiler for showing code metadata as comments in the pseudo-code

All the features have corresponding tests.

Support for code metadata is gated through the --enable-code-metadata feature. For reading/writing in the text format, --enable-annotations is also required.

Missing features:

    Support for function-level code metadata (offset 0)
    Extensive validation in validator.cc (like making sure that all metadata instances are at the same code offset of an instruction)

1 files changed, 29 insertions, 0 deletions

diff --git a/src/binary-reader-objdump.cc b/src/binary-reader-objdump.cc
index deb1167f..cb682698 100644
--- a/src/binary-reader-objdump.cc
+++ b/src/binary-reader-objdump.cc
@@ -1139,6 +1139,10 @@ class BinaryReaderObjdump : public BinaryReaderObjdumpBase {
   Result OnF32ConstExpr(uint32_t value) override;
   Result OnF64ConstExpr(uint64_t value) override;
   Result OnGlobalGetExpr(Index global_index) override;
+  Result OnCodeMetadataCount(Index function_index, Index count) override;
+  Result OnCodeMetadata(Offset code_offset,
+                        const void* data,
+                        Address size) override;
 
  private:
   Result InitExprToConstOffset(const InitExpr& expr, uint64_t* out_offset);
@@ -2192,6 +2196,31 @@ Result BinaryReaderObjdump::OnTagType(Index index, Index sig_index) {
   return Result::Ok;
 }
 
+Result BinaryReaderObjdump::OnCodeMetadataCount(Index function_index,
+                                                Index count) {
+  if (!ShouldPrintDetails()) {
+    return Result::Ok;
+  }
+  printf("   - func[%" PRIindex "]", function_index);
+  auto name = GetFunctionName(function_index);
+  if (!name.empty()) {
+    printf(" <" PRIstringview ">", WABT_PRINTF_STRING_VIEW_ARG(name));
+  }
+  printf(":\n");
+  return Result::Ok;
+}
+Result BinaryReaderObjdump::OnCodeMetadata(Offset code_offset,
+                                           const void* data,
+                                           Address size) {
+  if (!ShouldPrintDetails()) {
+    return Result::Ok;
+  }
+  printf("    - meta[%" PRIzx "]:\n", code_offset);
+
+  out_stream_->WriteMemoryDump(data, size, 0, PrintChars::Yes, "     - ");
+  return Result::Ok;
+}
+
 }  // end anonymous namespace
 
 std::string_view ObjdumpNames::Get(Index index) const {