Admit binary expression named property reads (#3021)

Author: rogeralsing

src/Asynkron.JsEngine/Execution/UnifiedBytecode/UnifiedBytecodeProductionEligibility.cs

@@ -1058,6 +1058,11 @@ private static bool TryFindExpressionDecline(
                         break;
                     }
 
+                    if (TryIsFirstBoundaryBinaryNamedPropertyReadCandidate(program, identifierConstants, activationSlots))
+                    {
+                        break;
+                    }
+
                     if (TryIsFirstBoundaryOptionalNamedChainCandidate(program, identifierConstants, activationSlots))
                     {
                         break;
@@ -1856,6 +1861,38 @@ private static bool TryIsFirstBoundaryObjectLiteralNamedPropertyReadCandidate(
         return true;
     }
 
+    private static bool TryIsFirstBoundaryBinaryNamedPropertyReadCandidate(
+        ExpressionProgram program,
+        ReadOnlySpan<IdentifierOperand> identifierConstants,
+        ActivationSlotShape activationSlots)
+    {
+        if (!TryMeasureSimpleBinaryOperandSpan(
+                program,
+                startIndex: 0,
+                identifierConstants,
+                activationSlots,
+                out var binarySpanLength) ||
+            binarySpanLength >= program.OperationCount)
+        {
+            return false;
+        }
+
+        var stringConstants = program.StringConstants.AsSpan();
+        for (var index = binarySpanLength; index < program.OperationCount; index++)
+        {
+            var operation = program.GetOperation(index);
+            if (operation.Kind != ExpressionOpKind.GetNamedProperty ||
+                operation.IsOptional ||
+                operation.ShortCircuitOnNullishTarget ||
+                operation.GetString(stringConstants).IsPrivateName())
+            {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
     /// <summary>
     /// Returns <c>true</c> when the <see cref="ExpressionOpKind.GetNamedProperty"/> operation at
     /// <paramref name="operationIndex"/> is the last op before a logical short-circuit jump

tests/Asynkron.JsEngine.Tests/UnifiedBytecodeProductionEligibilityTests.cs

@@ -2478,7 +2478,7 @@ function readBinaryTarget(a, b) {
         }
         """,
         "readBinaryTarget",
-        (int)UnifiedBytecodeProductionDeclineCode.PropertyReadBoundaryOutOfScope)]
+        (int)UnifiedBytecodeProductionDeclineCode.None)]
     [InlineData(
         """
         function readComputedObjectLiteralKey(box) {

tests/Asynkron.JsEngine.Tests/UnifiedBytecodeProductionInvocationTests.cs

@@ -3722,6 +3722,25 @@ static record => record.Message.Contains(
                 StringComparison.Ordinal));
     }
 
+    [Fact(Timeout = 5000)]
+    public async Task BinaryExpressionNamedPropertyRead_UsesUnifiedBytecodeProductionFastPath()
+    {
+        await using var engine = CreateEngine();
+        var result = await engine.Evaluate("""
+            function readBinaryTarget(left, right) {
+                return (left + right).length;
+            }
+
+            readBinaryTarget("xy", "z");
+            """);
+
+        Assert.Equal(3d, result);
+        Assert.Contains(CurrentLogger!.Collector.Snapshot(),
+            static record => record.Message.Contains(
+                "unified-bytecode-production-fast-path func=readBinaryTarget argc=2",
+                StringComparison.Ordinal));
+    }
+
     [Fact(Timeout = 5000)]
     public async Task TryCatch_GetterThrow_IsCaughtOnProductionFastPath()
     {