[vm/compiler] Add missing case for CP

Rationale:
Constant propagator was missing a case for a
double binary operator.

dart-lang#35321
dart-lang#35355



Change-Id: Ie88fe082e88b74651e798d516784737b36b4dcd1
Reviewed-on: https://dart-review.googlesource.com/c/86101
Reviewed-by: Ryan Macnak <[email protected]>
Commit-Queue: Aart Bik <[email protected]>

Author: aartbik

runtime/vm/compiler/backend/constant_propagator.cc

@@ -1160,6 +1160,9 @@ void ConstantPropagator::VisitBinaryDoubleOp(BinaryDoubleOpInstr* instr) {
     }
     const Double& result = Double::ZoneHandle(Double::NewCanonical(result_val));
     SetValue(instr, result);
+  } else if (IsConstant(left) && IsConstant(right)) {
+    // Both values known, but no rule to evaluate this further.
+    SetValue(instr, non_constant_);
   }
 }
 

tests/language_2/vm/regress_35321_test.dart

@@ -0,0 +1,34 @@
+// Copyright (c) 2018, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Proper CP on double op (dartbug.com/35321).
+//
+// VMOptions=--deterministic --optimization_counter_threshold=10
+
+import "package:expect/expect.dart";
+
+double foo(bool x) {
+  if (x) return 1.0;
+}
+
+int bar(int i) {
+  if (i < 0) {
+    return bar(i + 1);
+  } else if ((foo(i == 22) / 22.0) >= (1 / 0.0)) {
+    return 1;
+  }
+  return 0;
+}
+
+void main() {
+  for (int i = 0; i < 20; ++i) {
+    var x = -1;
+    try {
+      x = bar(i);
+    } catch (_) {
+      x = -2;
+    }
+    Expect.equals(-2, x);
+  }
+}