[Custom Descriptors] Update wasm-ctor-eval (#7689)

Update wasm-ctor-eval to serialize descriptor operands to struct.new for
those allocations that need them.

Author: tlively

scripts/test/fuzzing.py

@@ -124,6 +124,7 @@
     'heap2local-desc.wast',
     'minimize-rec-groups-desc.wast',
     'precompute-desc.wast',
+    'gc-desc.wast',
     # TODO: fix split_wast() on tricky escaping situations like a string ending
     #       in \\" (the " is not escaped - there is an escaped \ before it)
     'string-lifting-section.wast',

src/tools/wasm-ctor-eval.cpp

@@ -850,7 +850,7 @@ struct CtorEvalExternalInterface : EvallingModuleRunner::ExternalInterface {
     } else {
       // This is the first usage of this data. Generate a struct.new /
       // array.new for it.
-      auto& values = value.getGCData()->values;
+      auto& values = data->values;
       std::vector<Expression*> args;
 
       // The initial values for this allocation may themselves be GC
@@ -876,10 +876,15 @@ struct CtorEvalExternalInterface : EvallingModuleRunner::ExternalInterface {
         args.push_back(getSerialization(value));
       }
 
+      Expression* desc = nullptr;
+      if (data->desc.getGCData()) {
+        desc = getSerialization(data->desc);
+      }
+
       Expression* init;
       auto heapType = type.getHeapType();
       if (heapType.isStruct()) {
-        init = builder.makeStructNew(heapType, args);
+        init = builder.makeStructNew(heapType, args, desc);
       } else if (heapType.isArray()) {
         // TODO: for repeated identical values, can use ArrayNew
         init = builder.makeArrayNewFixed(heapType, args);

test/lit/ctor-eval/gc-desc.wast

@@ -0,0 +1,38 @@
+;; NOTE: Assertions have been generated by update_lit_checks.py --all-items and should not be edited.
+;; RUN: wasm-ctor-eval %s --ctors=ctor --kept-exports=ctor --quiet -all -S -o - | filecheck %s
+
+(module
+  (rec
+    ;; CHECK:      (rec
+    ;; CHECK-NEXT:  (type $struct (sub (descriptor $desc (struct))))
+    (type $struct (sub (descriptor $desc (struct))))
+    ;; CHECK:       (type $desc (describes $struct (struct)))
+    (type $desc (describes $struct (struct)))
+  )
+  ;; CHECK:      (type $2 (func))
+
+  ;; CHECK:      (global $ctor-eval$global_2 (ref (exact $desc)) (struct.new_default $desc))
+
+  ;; CHECK:      (global $ctor-eval$global (ref (exact $struct)) (struct.new_default $struct
+  ;; CHECK-NEXT:  (global.get $ctor-eval$global_2)
+  ;; CHECK-NEXT: ))
+
+  ;; CHECK:      (global $global (ref $struct) (global.get $ctor-eval$global))
+  (global $global (export "g") (ref $struct)
+    (struct.new $struct
+      (struct.new $desc)
+    )
+  )
+
+  ;; Export some arbitrary ctor so we do anything at all.
+  (func $ctor (export "ctor")
+    (nop)
+  )
+)
+;; CHECK:      (export "g" (global $global))
+
+;; CHECK:      (export "ctor" (func $ctor_1))
+
+;; CHECK:      (func $ctor_1 (type $2)
+;; CHECK-NEXT:  (nop)
+;; CHECK-NEXT: )