[dart2wasm] Add indirection for dispatch table calls.

In a future change we will add logic to `callDispatchTable` that performs a modified lookup if the provided selector is marked as "overrideable" by the dynamic_interface.yaml passed by a user.

Change-Id: Ie8991ca3ebf5d3ff1287cbfc4af58e1b1509826d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/401202
Reviewed-by: Martin Kustermann <[email protected]>
Commit-Queue: Nate Biggs <[email protected]>

Author: natebiggs

pkg/dart2wasm/lib/code_generator.dart

@@ -1877,6 +1877,8 @@ abstract class AstCodeGenerator
     pushReceiver(selector.signature);
 
     if (selector.targetRanges.length == 1) {
+      // TODO(natebiggs): Ensure dynamic modules exclude this.
+
       assert(selector.staticDispatchRanges.length == 1);
       final target = selector.targetRanges[0].target;
       final signature = translator.signatureForDirectCall(target);
@@ -1887,6 +1889,8 @@ abstract class AstCodeGenerator
     }
 
     if (selector.targetRanges.isEmpty) {
+      // TODO(natebiggs): Ensure dynamic modules exclude this.
+
       // Unreachable call
       b.comment("Virtual call of ${selector.name} with no targets"
           " at ${node.location}");
@@ -1907,22 +1911,15 @@ abstract class AstCodeGenerator
     pushArguments(selector.signature, selector.paramInfo);
 
     if (selector.staticDispatchRanges.isNotEmpty) {
+      // TODO(natebiggs): Ensure dynamic modules exclude this.
+
       b.invoke(translator
           .getPolymorphicDispatchersForModule(b.module)
           .getPolymorphicDispatcher(selector));
     } else {
-      final offset = selector.offset!;
       b.comment("Instance $kind of '${selector.name}'");
       b.local_get(receiverVar);
-      b.struct_get(translator.topInfo.struct, FieldIndex.classId);
-      if (offset != 0) {
-        b.i32_const(offset);
-        b.i32_add();
-      }
-      b.call_indirect(
-          selector.signature, translator.dispatchTable.getWasmTable(b.module));
-
-      translator.functions.recordSelectorUse(selector);
+      translator.callDispatchTable(b, selector);
     }
 
     return translator.outputOrVoid(selector.signature.outputs);

pkg/dart2wasm/lib/dynamic_forwarders.dart

@@ -773,16 +773,7 @@ void generateNoSuchMethodCall(
 
   // Get class id for virtual call
   pushReceiver();
-  b.struct_get(translator.topInfo.struct, FieldIndex.classId);
-
-  // Virtual call to noSuchMethod
-  int selectorOffset = noSuchMethodSelector.offset!;
-  if (selectorOffset != 0) {
-    b.i32_const(selectorOffset);
-    b.i32_add();
-  }
-
-  b.call_indirect(noSuchMethodWasmFunctionType);
+  translator.callDispatchTable(b, noSuchMethodSelector);
 }
 
 class ClassIdRange {

pkg/dart2wasm/lib/translator.dart

@@ -485,6 +485,17 @@ class Translator with KernelNodes {
     return function.type.outputs;
   }
 
+  void callDispatchTable(w.InstructionsBuilder b, SelectorInfo selector) {
+    // TODO(natebiggs): Handle dispatch to dynamic module overrideable members.
+    b.struct_get(topInfo.struct, FieldIndex.classId);
+    if (selector.offset! != 0) {
+      b.i32_const(selector.offset!);
+      b.i32_add();
+    }
+    b.call_indirect(selector.signature, dispatchTable.getWasmTable(b.module));
+    functions.recordSelectorUse(selector);
+  }
+
   Class classForType(DartType type) {
     return type is InterfaceType
         ? type.classNode
@@ -2000,12 +2011,7 @@ class PolymorphicDispatcherCodeGenerator implements CodeGenerator {
         b.local_get(paramLocals[i]);
       }
       b.local_get(paramLocals[0]);
-      b.struct_get(translator.topInfo.struct, FieldIndex.classId);
-      b.i32_const(selector.offset!);
-      b.i32_add();
-      b.call_indirect(
-          signature, translator.dispatchTable.getWasmTable(b.module));
-      translator.functions.recordSelectorUse(selector);
+      translator.callDispatchTable(b, selector);
     }
 
     b.local_get(paramLocals[0]);