[Wasm GC] Allow subtyping in arguments to struct.get etc. Fixes #3636 (#3644)

Note that Binaryen "canonicalizes" the type, so in the test output here
we end up with $grandchild twice. This is a consequence of us not
storing the heap type as an extra field. I can't think of a downside to
this canonicalization, aside from losing perfect roundtripping, but I think
that's a worthwhile tradeoff for efficiency as we've been thinking so far.

Fixes #3636

7 files changed, 45 insertions, 12 deletions

diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index 1f54a0038..d5579eedf 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -6417,7 +6417,7 @@ void WasmBinaryBuilder::validateHeapTypeUsingChild(Expression* child,
     return;
   }
   if ((!child->type.isRef() && !child->type.isRtt()) ||
-      child->type.getHeapType() != heapType) {
+      !HeapType::isSubType(child->type.getHeapType(), heapType)) {
     throwError("bad heap type: expected " + heapType.toString() +
                " but found " + child->type.toString());
   }
diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index 1271ff603..11121ced6 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -3451,7 +3451,7 @@ void SExpressionWasmBuilder::validateHeapTypeUsingChild(Expression* child,
     return;
   }
   if ((!child->type.isRef() && !child->type.isRtt()) ||
-      child->type.getHeapType() != heapType) {
+      !HeapType::isSubType(child->type.getHeapType(), heapType)) {
     throw ParseException("bad heap type: expected " + heapType.toString() +
                            " but found " + child->type.toString(),
                          s.line,
diff --git a/test/example/c-api-kitchen-sink.c b/test/example/c-api-kitchen-sink.c
index 4faf7aa5e..04f552069 100644
--- a/test/example/c-api-kitchen-sink.c
+++ b/test/example/c-api-kitchen-sink.c
@@ -731,13 +731,27 @@ void test_core() {
     BinaryenRefEq(module,
                   BinaryenRefNull(module, BinaryenTypeEqref()),
                   BinaryenRefNull(module, BinaryenTypeEqref())),
-    BinaryenRefIs(module, BinaryenRefIsFunc(), BinaryenRefNull(module, BinaryenTypeAnyref())),
-    BinaryenRefIs(module, BinaryenRefIsData(), BinaryenRefNull(module, BinaryenTypeAnyref())),
-    BinaryenRefIs(module, BinaryenRefIsI31(), BinaryenRefNull(module, BinaryenTypeAnyref())),
-    BinaryenRefAs(module, BinaryenRefAsNonNull(), BinaryenRefNull(module, BinaryenTypeAnyref())),
-    BinaryenRefAs(module, BinaryenRefAsFunc(), BinaryenRefNull(module, BinaryenTypeAnyref())),
-    BinaryenRefAs(module, BinaryenRefAsData(), BinaryenRefNull(module, BinaryenTypeAnyref())),
-    BinaryenRefAs(module, BinaryenRefAsI31(), BinaryenRefNull(module, BinaryenTypeAnyref())),
+    BinaryenRefIs(module,
+                  BinaryenRefIsFunc(),
+                  BinaryenRefNull(module, BinaryenTypeAnyref())),
+    BinaryenRefIs(module,
+                  BinaryenRefIsData(),
+                  BinaryenRefNull(module, BinaryenTypeAnyref())),
+    BinaryenRefIs(module,
+                  BinaryenRefIsI31(),
+                  BinaryenRefNull(module, BinaryenTypeAnyref())),
+    BinaryenRefAs(module,
+                  BinaryenRefAsNonNull(),
+                  BinaryenRefNull(module, BinaryenTypeAnyref())),
+    BinaryenRefAs(module,
+                  BinaryenRefAsFunc(),
+                  BinaryenRefNull(module, BinaryenTypeAnyref())),
+    BinaryenRefAs(module,
+                  BinaryenRefAsData(),
+                  BinaryenRefNull(module, BinaryenTypeAnyref())),
+    BinaryenRefAs(module,
+                  BinaryenRefAsI31(),
+                  BinaryenRefNull(module, BinaryenTypeAnyref())),
     // Exception handling
     BinaryenTry(module, NULL, tryBody, catchEvents, 1, catchBodies, 2, NULL),
     // (try $try_outer
diff --git a/test/heap-types.wast b/test/heap-types.wast
index e645ee74d..f340e9dee 100644
--- a/test/heap-types.wast
+++ b/test/heap-types.wast
@@ -58,6 +58,10 @@
       (struct.get_s $struct.B 0 (local.get $tB))
     )
     (drop
+      ;; immutable fields allow subtyping.
+      (struct.get $child 0 (ref.null $grandchild))
+    )
+    (drop
       (ref.null $struct.A)
     )
     (drop
diff --git a/test/heap-types.wast.from-wast b/test/heap-types.wast.from-wast
index b4228fd20..6c07baf9a 100644
--- a/test/heap-types.wast.from-wast
+++ b/test/heap-types.wast.from-wast
@@ -5,6 +5,7 @@
  (type $vector (array (mut f64)))
  (type $anyref_=>_none (func (param anyref)))
  (type $parent (struct ))
+ (type $grandchild (struct (field i32) (field i64)))
  (type $struct.C (struct (field $named-mut (mut f32))))
  (type $none_=>_none (func))
  (type $rtt_1_$parent_=>_none (func (param (rtt 1 $parent))))
@@ -12,7 +13,6 @@
  (type $ref?|$struct.A|_=>_ref?|$struct.B| (func (param (ref null $struct.A)) (result (ref null $struct.B))))
  (type $ref?|$vector|_=>_ref?|$matrix| (func (param (ref null $vector)) (result (ref null $matrix))))
  (type $child (struct (field i32)))
- (type $grandchild (struct (field i32) (field i64)))
  (type $words (array (mut i32)))
  (type $bytes (array (mut i8)))
  (global $rttparent (rtt 0 $parent) (rtt.canon $parent))
@@ -62,6 +62,11 @@
    )
   )
   (drop
+   (struct.get $grandchild 0
+    (ref.null $grandchild)
+   )
+  )
+  (drop
    (ref.null $struct.A)
   )
   (drop
diff --git a/test/heap-types.wast.fromBinary b/test/heap-types.wast.fromBinary
index 2fe6adbe1..795c789ca 100644
--- a/test/heap-types.wast.fromBinary
+++ b/test/heap-types.wast.fromBinary
@@ -5,6 +5,7 @@
  (type $vector (array (mut f64)))
  (type $anyref_=>_none (func (param anyref)))
  (type $parent (struct ))
+ (type $grandchild (struct (field i32) (field i64)))
  (type $struct.C (struct (field $named-mut (mut f32))))
  (type $none_=>_none (func))
  (type $rtt_1_$parent_=>_none (func (param (rtt 1 $parent))))
@@ -12,7 +13,6 @@
  (type $ref?|$struct.A|_=>_ref?|$struct.B| (func (param (ref null $struct.A)) (result (ref null $struct.B))))
  (type $ref?|$vector|_=>_ref?|$matrix| (func (param (ref null $vector)) (result (ref null $matrix))))
  (type $child (struct (field i32)))
- (type $grandchild (struct (field i32) (field i64)))
  (type $words (array (mut i32)))
  (type $bytes (array (mut i8)))
  (global $rttparent (rtt 0 $parent) (rtt.canon $parent))
@@ -62,6 +62,11 @@
    )
   )
   (drop
+   (struct.get $grandchild 0
+    (ref.null $grandchild)
+   )
+  )
+  (drop
    (ref.null $struct.A)
   )
   (drop
diff --git a/test/heap-types.wast.fromBinary.noDebugInfo b/test/heap-types.wast.fromBinary.noDebugInfo
index dbfcb9cdd..6b1641407 100644
--- a/test/heap-types.wast.fromBinary.noDebugInfo
+++ b/test/heap-types.wast.fromBinary.noDebugInfo
@@ -5,6 +5,7 @@
  (type $[mut:f64] (array (mut f64)))
  (type $anyref_=>_none (func (param anyref)))
  (type ${} (struct ))
+ (type ${i32_i64} (struct (field i32) (field i64)))
  (type ${mut:f32} (struct (field (mut f32))))
  (type $none_=>_none (func))
  (type $rtt_1_{}_=>_none (func (param (rtt 1 ${}))))
@@ -12,7 +13,6 @@
  (type $ref?|{i32_f32_f64}|_=>_ref?|{i8_mut:i16_ref?|{i32_f32_f64}|_mut:ref?|{i32_f32_f64}|}| (func (param (ref null ${i32_f32_f64})) (result (ref null ${i8_mut:i16_ref?|{i32_f32_f64}|_mut:ref?|{i32_f32_f64}|}))))
  (type $ref?|[mut:f64]|_=>_ref?|[ref?|[mut:f64]|]| (func (param (ref null $[mut:f64])) (result (ref null $[ref?|[mut:f64]|]))))
  (type ${i32} (struct (field i32)))
- (type ${i32_i64} (struct (field i32) (field i64)))
  (type $[mut:i32] (array (mut i32)))
  (type $[mut:i8] (array (mut i8)))
  (global $global$0 (rtt 0 ${}) (rtt.canon ${}))
@@ -62,6 +62,11 @@
    )
   )
   (drop
+   (struct.get ${i32_i64} 0
+    (ref.null ${i32_i64})
+   )
+  )
+  (drop
    (ref.null ${i32_f32_f64})
   )
   (drop