Port and integrate the irregexp engine from V8

runtime/vm/flow_graph_range_analysis.cc

Index: runtime/vm/flow_graph_range_analysis.cc
diff --git a/runtime/vm/flow_graph_range_analysis.cc b/runtime/vm/flow_graph_range_analysis.cc
index e7268595135fc69c0c29f5866b4f533250618c45..b0ec8cf9d888babd58c0a379acd092c40547c41d 100644
--- a/runtime/vm/flow_graph_range_analysis.cc
+++ b/runtime/vm/flow_graph_range_analysis.cc
@@ -1985,6 +1985,22 @@ void LoadIndexedInstr::InferRange(RangeAnalysis* analysis, Range* range) {
 }
 
 
+void LoadCodeUnitsInstr::InferRange(RangeAnalysis* analysis, Range* range) {
+  ASSERT(class_id() == kOneByteStringCid ||
+         class_id() == kTwoByteStringCid);
+  switch (class_id()) {
+    case kOneByteStringCid:
+    case kTwoByteStringCid:
+      *range = Range(RangeBoundary::FromConstant(0),
+                     RangeBoundary::FromConstant(0xFFFFFFFF));

[Florian Schneider, 2014/10/01 17:04:15]

s/0xFFFFFFFF/kMaxUint32/

[jgruber1, 2014/10/03 18:59:54]

Done.

+      break;
+    default:
+      UNREACHABLE();
+      break;
+  }
+}
+
+
 void IfThenElseInstr::InferRange(RangeAnalysis* analysis, Range* range) {
   const intptr_t min = Utils::Minimum(if_true_, if_false_);
   const intptr_t max = Utils::Maximum(if_true_, if_false_);