Add support for reference types proposal (#2451)

This adds support for the reference type proposal. This includes support
for all reference types (`anyref`, `funcref`(=`anyfunc`), and `nullref`)
and four new instructions: `ref.null`, `ref.is_null`, `ref.func`, and
new typed `select`. This also adds subtype relationship support between
reference types.

This does not include table instructions yet. This also does not include
wasm2js support.

Fixes #2444 and fixes #2447.

1 files changed, 37 insertions, 3 deletions

diff --git a/src/passes/Print.cpp b/src/passes/Print.cpp
index 5efd1fd28..51e78c8a7 100644
--- a/src/passes/Print.cpp
+++ b/src/passes/Print.cpp
@@ -1333,7 +1333,12 @@ struct PrintExpressionContents
     }
     restoreNormalColor(o);
   }
-  void visitSelect(Select* curr) { prepareColor(o) << "select"; }
+  void visitSelect(Select* curr) {
+    prepareColor(o) << "select";
+    if (curr->type.isRef()) {
+      o << " (result " << curr->type << ')';
+    }
+  }
   void visitDrop(Drop* curr) { printMedium(o, "drop"); }
   void visitReturn(Return* curr) { printMedium(o, "return"); }
   void visitHost(Host* curr) {
@@ -1346,6 +1351,12 @@ struct PrintExpressionContents
         break;
     }
   }
+  void visitRefNull(RefNull* curr) { printMedium(o, "ref.null"); }
+  void visitRefIsNull(RefIsNull* curr) { printMedium(o, "ref.is_null"); }
+  void visitRefFunc(RefFunc* curr) {
+    printMedium(o, "ref.func ");
+    printName(curr->func, o);
+  }
   void visitTry(Try* curr) {
     printMedium(o, "try");
     if (curr->type.isConcrete()) {
@@ -1852,6 +1863,23 @@ struct PrintSExpression : public OverriddenVisitor<PrintSExpression> {
       }
     }
   }
+  void visitRefNull(RefNull* curr) {
+    o << '(';
+    PrintExpressionContents(currFunction, o).visit(curr);
+    o << ')';
+  }
+  void visitRefIsNull(RefIsNull* curr) {
+    o << '(';
+    PrintExpressionContents(currFunction, o).visit(curr);
+    incIndent();
+    printFullLine(curr->value);
+    decIndent();
+  }
+  void visitRefFunc(RefFunc* curr) {
+    o << '(';
+    PrintExpressionContents(currFunction, o).visit(curr);
+    o << ')';
+  }
   // try-catch-end is written in the folded wat format as
   // (try
   //   ...
@@ -2434,13 +2462,15 @@ WasmPrinter::printStackInst(StackInst* inst, std::ostream& o, Function* func) {
     }
     case StackInst::BlockBegin:
     case StackInst::IfBegin:
-    case StackInst::LoopBegin: {
+    case StackInst::LoopBegin:
+    case StackInst::TryBegin: {
       o << getExpressionName(inst->origin);
       break;
     }
     case StackInst::BlockEnd:
     case StackInst::IfEnd:
-    case StackInst::LoopEnd: {
+    case StackInst::LoopEnd:
+    case StackInst::TryEnd: {
       o << "end (" << inst->type << ')';
       break;
     }
@@ -2448,6 +2478,10 @@ WasmPrinter::printStackInst(StackInst* inst, std::ostream& o, Function* func) {
       o << "else";
       break;
     }
+    case StackInst::Catch: {
+      o << "catch";
+      break;
+    }
     default:
       WASM_UNREACHABLE("unexpeted op");
   }