[threads] Shared basic heap types (#6667)

Implement binary and text parsing and printing of shared basic heap types and
incorporate them into the type hierarchy.

To avoid the massive amount of code duplication that would be necessary if we
were to add separate enum variants for each of the shared basic heap types, use
bit 0 to indicate whether the type is shared and replace `getBasic()` with
`getBasic(Unshared)`, which clears that bit. Update all the use sites to record
whether the original type was shared and produce shared or unshared output
without code duplication.

1 files changed, 54 insertions, 37 deletions

diff --git a/src/parser/parsers.h b/src/parser/parsers.h
index 1c329aecb..db450e3c6 100644
--- a/src/parser/parsers.h
+++ b/src/parser/parsers.h
@@ -27,6 +27,8 @@ namespace wasm::WATParser {
 using namespace std::string_view_literals;
 
 // Types
+template<typename Ctx>
+Result<typename Ctx::HeapTypeT> absheaptype(Ctx&, Shareability);
 template<typename Ctx> Result<typename Ctx::HeapTypeT> heaptype(Ctx&);
 template<typename Ctx> MaybeResult<typename Ctx::RefTypeT> maybeRefType(Ctx&);
 template<typename Ctx> Result<typename Ctx::RefTypeT> reftype(Ctx&);
@@ -358,58 +360,73 @@ template<typename Ctx> Result<> module(Ctx&);
 // Types
 // =====
 
-// heaptype ::= x:typeidx => types[x]
-//            | 'func'    => func
-//            | 'extern'  => extern
-template<typename Ctx> Result<typename Ctx::HeapTypeT> heaptype(Ctx& ctx) {
+// absheaptype ::= 'func' | 'extern' | ...
+template<typename Ctx>
+Result<typename Ctx::HeapTypeT> absheaptype(Ctx& ctx, Shareability share) {
   if (ctx.in.takeKeyword("func"sv)) {
-    return ctx.makeFuncType();
+    return ctx.makeFuncType(share);
   }
   if (ctx.in.takeKeyword("any"sv)) {
-    return ctx.makeAnyType();
+    return ctx.makeAnyType(share);
   }
   if (ctx.in.takeKeyword("extern"sv)) {
-    return ctx.makeExternType();
+    return ctx.makeExternType(share);
   }
   if (ctx.in.takeKeyword("eq"sv)) {
-    return ctx.makeEqType();
+    return ctx.makeEqType(share);
   }
   if (ctx.in.takeKeyword("i31"sv)) {
-    return ctx.makeI31Type();
+    return ctx.makeI31Type(share);
   }
   if (ctx.in.takeKeyword("struct"sv)) {
-    return ctx.makeStructType();
+    return ctx.makeStructType(share);
   }
   if (ctx.in.takeKeyword("array"sv)) {
-    return ctx.makeArrayType();
+    return ctx.makeArrayType(share);
   }
   if (ctx.in.takeKeyword("exn"sv)) {
-    return ctx.makeExnType();
+    return ctx.makeExnType(share);
   }
   if (ctx.in.takeKeyword("string"sv)) {
-    return ctx.makeStringType();
+    return ctx.makeStringType(share);
   }
   if (ctx.in.takeKeyword("cont"sv)) {
-    return ctx.makeContType();
+    return ctx.makeContType(share);
   }
   if (ctx.in.takeKeyword("none"sv)) {
-    return ctx.makeNoneType();
+    return ctx.makeNoneType(share);
   }
   if (ctx.in.takeKeyword("noextern"sv)) {
-    return ctx.makeNoextType();
+    return ctx.makeNoextType(share);
   }
   if (ctx.in.takeKeyword("nofunc"sv)) {
-    return ctx.makeNofuncType();
+    return ctx.makeNofuncType(share);
   }
   if (ctx.in.takeKeyword("noexn"sv)) {
-    return ctx.makeNoexnType();
+    return ctx.makeNoexnType(share);
   }
   if (ctx.in.takeKeyword("nocont"sv)) {
-    return ctx.makeNocontType();
+    return ctx.makeNocontType(share);
   }
-  auto type = typeidx(ctx);
-  CHECK_ERR(type);
-  return *type;
+  return ctx.in.err("expected abstract heap type");
+}
+
+// heaptype ::= x:typeidx                      => types[x]
+//            | t:absheaptype                  => unshared t
+//            | '(' 'shared' t:absheaptype ')' => shared t
+template<typename Ctx> Result<typename Ctx::HeapTypeT> heaptype(Ctx& ctx) {
+  if (auto t = maybeTypeidx(ctx)) {
+    CHECK_ERR(t);
+    return *t;
+  }
+
+  auto share = ctx.in.takeSExprStart("shared"sv) ? Shared : Unshared;
+  auto t = absheaptype(ctx, share);
+  CHECK_ERR(t);
+  if (share == Shared && !ctx.in.takeRParen()) {
+    return ctx.in.err("expected end of shared abstract heap type");
+  }
+  return *t;
 }
 
 // reftype ::= 'funcref'   => funcref
@@ -422,49 +439,49 @@ template<typename Ctx> Result<typename Ctx::HeapTypeT> heaptype(Ctx& ctx) {
 //           | '(' ref null? t:heaptype ')' => ref null? t
 template<typename Ctx> MaybeResult<typename Ctx::TypeT> maybeReftype(Ctx& ctx) {
   if (ctx.in.takeKeyword("funcref"sv)) {
-    return ctx.makeRefType(ctx.makeFuncType(), Nullable);
+    return ctx.makeRefType(ctx.makeFuncType(Unshared), Nullable);
   }
   if (ctx.in.takeKeyword("externref"sv)) {
-    return ctx.makeRefType(ctx.makeExternType(), Nullable);
+    return ctx.makeRefType(ctx.makeExternType(Unshared), Nullable);
   }
   if (ctx.in.takeKeyword("anyref"sv)) {
-    return ctx.makeRefType(ctx.makeAnyType(), Nullable);
+    return ctx.makeRefType(ctx.makeAnyType(Unshared), Nullable);
   }
   if (ctx.in.takeKeyword("eqref"sv)) {
-    return ctx.makeRefType(ctx.makeEqType(), Nullable);
+    return ctx.makeRefType(ctx.makeEqType(Unshared), Nullable);
   }
   if (ctx.in.takeKeyword("i31ref"sv)) {
-    return ctx.makeRefType(ctx.makeI31Type(), Nullable);
+    return ctx.makeRefType(ctx.makeI31Type(Unshared), Nullable);
   }
   if (ctx.in.takeKeyword("structref"sv)) {
-    return ctx.makeRefType(ctx.makeStructType(), Nullable);
+    return ctx.makeRefType(ctx.makeStructType(Unshared), Nullable);
   }
   if (ctx.in.takeKeyword("arrayref"sv)) {
-    return ctx.makeRefType(ctx.makeArrayType(), Nullable);
+    return ctx.makeRefType(ctx.makeArrayType(Unshared), Nullable);
   }
   if (ctx.in.takeKeyword("exnref"sv)) {
-    return ctx.makeRefType(ctx.makeExnType(), Nullable);
+    return ctx.makeRefType(ctx.makeExnType(Unshared), Nullable);
   }
   if (ctx.in.takeKeyword("stringref"sv)) {
-    return ctx.makeRefType(ctx.makeStringType(), Nullable);
+    return ctx.makeRefType(ctx.makeStringType(Unshared), Nullable);
   }
   if (ctx.in.takeKeyword("contref"sv)) {
-    return ctx.makeRefType(ctx.makeContType(), Nullable);
+    return ctx.makeRefType(ctx.makeContType(Unshared), Nullable);
   }
   if (ctx.in.takeKeyword("nullref"sv)) {
-    return ctx.makeRefType(ctx.makeNoneType(), Nullable);
+    return ctx.makeRefType(ctx.makeNoneType(Unshared), Nullable);
   }
   if (ctx.in.takeKeyword("nullexternref"sv)) {
-    return ctx.makeRefType(ctx.makeNoextType(), Nullable);
+    return ctx.makeRefType(ctx.makeNoextType(Unshared), Nullable);
   }
   if (ctx.in.takeKeyword("nullfuncref"sv)) {
-    return ctx.makeRefType(ctx.makeNofuncType(), Nullable);
+    return ctx.makeRefType(ctx.makeNofuncType(Unshared), Nullable);
   }
   if (ctx.in.takeKeyword("nullexnref"sv)) {
-    return ctx.makeRefType(ctx.makeNoexnType(), Nullable);
+    return ctx.makeRefType(ctx.makeNoexnType(Unshared), Nullable);
   }
   if (ctx.in.takeKeyword("nullcontref"sv)) {
-    return ctx.makeRefType(ctx.makeNocontType(), Nullable);
+    return ctx.makeRefType(ctx.makeNocontType(Unshared), Nullable);
   }
 
   if (!ctx.in.takeSExprStart("ref"sv)) {