dart2js: Inhibit code motion of indexing

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

Index: pkg/compiler/lib/src/ssa/nodes.dart
diff --git a/pkg/compiler/lib/src/ssa/nodes.dart b/pkg/compiler/lib/src/ssa/nodes.dart
index 3fec3f87be2f26e1ffa7cae80cb3b2350ae00415..46eb7c9c4ed2fa9e97b567549b6f17a0fbc53b9a 100644
--- a/pkg/compiler/lib/src/ssa/nodes.dart
+++ b/pkg/compiler/lib/src/ssa/nodes.dart
@@ -2623,6 +2623,9 @@ class HIndex extends HInstruction {
   HInstruction get receiver => inputs[0];
   HInstruction get index => inputs[1];
 
+  // Implicit dependency on HBoundsCheck or constraints on index.

[Siggi Cherem (dart-lang), 2016/09/07 14:27:01]

maybe add a TODO to make this more precise & refer to the bug?

+  bool get isMovable => false;
+
   HInstruction getDartReceiver(Compiler compiler) => receiver;
   bool onlyThrowsNSM() => true;
   bool canThrow() => receiver.canBeNull();
@@ -2653,6 +2656,9 @@ class HIndexAssign extends HInstruction {
   HInstruction get index => inputs[1];
   HInstruction get value => inputs[2];
 
+  // Implicit dependency on HBoundsCheck or constraints on index.
+  bool get isMovable => false;
+
   HInstruction getDartReceiver(Compiler compiler) => receiver;
   bool onlyThrowsNSM() => true;
   bool canThrow() => receiver.canBeNull();