[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.

2 files changed, 8 insertions, 4 deletions

diff --git a/src/tools/fuzzing/fuzzing.cpp b/src/tools/fuzzing/fuzzing.cpp
index 57c7ec6b0..6b54ac56d 100644
--- a/src/tools/fuzzing/fuzzing.cpp
+++ b/src/tools/fuzzing/fuzzing.cpp
@@ -2556,7 +2556,8 @@ Expression* TranslateToFuzzReader::makeBasicRef(Type type) {
   auto heapType = type.getHeapType();
   assert(heapType.isBasic());
   assert(wasm.features.hasReferenceTypes());
-  switch (heapType.getBasic()) {
+  assert(!heapType.isShared() && "TODO: handle shared types");
+  switch (heapType.getBasic(Unshared)) {
     case HeapType::ext: {
       auto null = builder.makeRefNull(HeapType::ext);
       // TODO: support actual non-nullable externrefs via imported globals or
@@ -4233,7 +4234,8 @@ HeapType TranslateToFuzzReader::getSubType(HeapType type) {
     return type;
   }
   if (type.isBasic() && oneIn(2)) {
-    switch (type.getBasic()) {
+    assert(!type.isShared() && "TODO: handle shared types");
+    switch (type.getBasic(Unshared)) {
       case HeapType::func:
         // TODO: Typed function references.
         return pick(FeatureOptions<HeapType>()
diff --git a/src/tools/fuzzing/heap-types.cpp b/src/tools/fuzzing/heap-types.cpp
index 08b4c4453..127d4f5ba 100644
--- a/src/tools/fuzzing/heap-types.cpp
+++ b/src/tools/fuzzing/heap-types.cpp
@@ -377,7 +377,8 @@ struct HeapTypeGeneratorImpl {
       if (rand.oneIn(8)) {
         return type.getBottom();
       }
-      switch (type.getBasic()) {
+      assert(!type.isShared() && "TODO: handle shared types");
+      switch (type.getBasic(Unshared)) {
         case HeapType::func:
           return pickSubFunc();
         case HeapType::cont:
@@ -438,7 +439,8 @@ struct HeapTypeGeneratorImpl {
     // This is not a constructed type, so it must be a basic type.
     assert(type.isBasic());
     candidates.push_back(type);
-    switch (type.getBasic()) {
+    assert(!type.isShared() && "TODO: handle shared types");
+    switch (type.getBasic(Unshared)) {
       case HeapType::ext:
       case HeapType::func:
       case HeapType::exn: