[dart2js] Use static type refinement for getters in SSA

This helps with generic fields of classes that have contexts with
concrete types, e.g Flutter's `IntTween extends Tween<int>` has `int?`
fields `begin` and `end`. This helps remove some `HPrimitiveCheck`
instructions.

Bug: #60327
Change-Id: Ic2022cc15e024f596ad30f3134ec6c325c892dcf
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/426660
Commit-Queue: Stephen Adams <[email protected]>
Reviewed-by: Mayank Patke <[email protected]>

Author: rakudrama

pkg/compiler/lib/src/ssa/builder.dart

@@ -7031,7 +7031,9 @@ class KernelSsaGraphBuilder extends ir.VisitorDefault<void>
       }
     }
 
-    if (node is ir.InstanceInvocation || node is ir.FunctionInvocation) {
+    if (node is ir.InstanceInvocation ||
+        node is ir.FunctionInvocation ||
+        node is ir.InstanceGet) {
       final staticType =
           _abstractValueDomain
               .createFromStaticType(_getStaticType(node as ir.Expression))
@@ -7042,9 +7044,9 @@ class KernelSsaGraphBuilder extends ir.VisitorDefault<void>
       // here.
       if (!_possiblyLegacyJavaScriptObject(selector, receiverType)) {
         invoke.staticType = staticType;
-        invoke.instructionType = _abstractValueDomain.intersection(
+        invoke.instructionType = invoke.computeInstructionType(
           resultType,
-          staticType,
+          _abstractValueDomain,
         );
       }
     }

pkg/compiler/lib/src/ssa/nodes.dart

@@ -1965,6 +1965,20 @@ abstract class HInvokeDynamic extends HInvoke implements InstructionContext {
     );
   }
 
+  /// Returns [value] narrowed by the [staticType].
+  AbstractValue computeInstructionType(
+    AbstractValue value,
+    AbstractValueDomain abstractValueDomain,
+  ) {
+    if (staticType == null) return value;
+    final narrowed = abstractValueDomain.intersection(value, staticType!);
+    // Preserve the sentinel in [value] since the static type does not include
+    // a sentinel and the intersection would remove it.
+    return abstractValueDomain.isLateSentinel(value).isPotentiallyTrue
+        ? abstractValueDomain.includeLateSentinel(narrowed)
+        : narrowed;
+  }
+
   @override
   String toString() => 'invoke dynamic: selector=$selector, mask=$receiverType';
 

pkg/compiler/lib/src/ssa/types_propagation.dart

@@ -446,10 +446,7 @@ class SsaTypePropagator extends HBaseVisitor<AbstractValue>
       results,
       closedWorld,
     );
-    if (node.staticType != null) {
-      result = abstractValueDomain.intersection(result, node.staticType!);
-    }
-    return result;
+    return node.computeInstructionType(result, abstractValueDomain);
   }
 
   @override