Preserve Function HeapTypes (#3952)

When using nominal types, func.ref of two functions with identical signatures
but different HeapTypes will yield different types. To preserve these semantics,
Functions need to track their HeapTypes, not just their Signatures.

This PR replaces the Signature field in Function with a HeapType field and adds
new utility methods to make it almost as simple to update and query the function
HeapType as it was to update and query the Function Signature.

1 files changed, 4 insertions, 4 deletions

diff --git a/src/tools/wasm-reduce.cpp b/src/tools/wasm-reduce.cpp
index 48435fac0..ed2b9b564 100644
--- a/src/tools/wasm-reduce.cpp
+++ b/src/tools/wasm-reduce.cpp
@@ -483,7 +483,7 @@ struct Reducer
         auto* save = curr;
         Unreachable un;
         Nop nop;
-        bool useUnreachable = getFunction()->sig.results != Type::none;
+        bool useUnreachable = getFunction()->getResults() != Type::none;
         if (useUnreachable) {
           replaceCurrent(&un);
         } else {
@@ -977,7 +977,7 @@ struct Reducer
       auto* func = module->functions[0].get();
       // We can't remove something that might have breaks to it.
       if (!func->imported() && !Properties::isNamedControlFlow(func->body)) {
-        auto funcSig = func->sig;
+        auto funcType = func->type;
         auto* funcBody = func->body;
         for (auto* child : ChildIterator(func->body)) {
           if (!(child->type.isConcrete() || child->type == Type::none)) {
@@ -985,7 +985,7 @@ struct Reducer
           }
           // Try to replace the body with the child, fixing up the function
           // to accept it.
-          func->sig.results = child->type;
+          func->type = Signature(funcType.getSignature().params, child->type);
           func->body = child;
           if (writeAndTestReduction()) {
             // great, we succeeded!
@@ -994,7 +994,7 @@ struct Reducer
             break;
           }
           // Undo.
-          func->sig = funcSig;
+          func->type = funcType;
           func->body = funcBody;
         }
       }