Narrow String::CharAt from int32_t to uint16_t.

runtime/vm/flow_graph_optimizer.cc

 // Copyright (c) 2013, 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.
 
 #include "vm/flow_graph_optimizer.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
 #include "vm/cpu.h"
 #include "vm/dart_entry.h"
@@ skipping 1829 matching lines @@
     right = temp;
   }
   if (IsLengthOneString(left)) {
     // Optimize if left is a string with length one (either constant or
     // result of string-from-char-code.
     if (left->IsConstant()) {
       ConstantInstr* left_const = left->AsConstant();
       const String& str = String::Cast(left_const->value());
       ASSERT(str.Length() == 1);
       ConstantInstr* char_code_left = flow_graph()->GetConstant(
-          Smi::ZoneHandle(I, Smi::New(str.CharAt(0))));
+          Smi::ZoneHandle(I, Smi::New(static_cast<intptr_t>(str.CharAt(0)))));
       left_val = new(I) Value(char_code_left);
     } else if (left->IsStringFromCharCode()) {
       // Use input of string-from-charcode as left value.
       StringFromCharCodeInstr* instr = left->AsStringFromCharCode();
       left_val = new(I) Value(instr->char_code()->definition());
       to_remove_left = instr;
     } else {
       // IsLengthOneString(left) should have been false.
       UNREACHABLE();
     }
@@ skipping 6145 matching lines @@
   }
 }
 
 
 void ConstantPropagator::VisitStringToCharCode(StringToCharCodeInstr* instr) {
   const Object& o = instr->str()->definition()->constant_value();
   if (o.IsNull() || IsNonConstant(o)) {
     SetValue(instr, non_constant_);
   } else if (IsConstant(o)) {
     const String& str = String::Cast(o);
-    const intptr_t result = (str.Length() == 1) ? str.CharAt(0) : -1;
+    const intptr_t result =
+        (str.Length() == 1) ? static_cast<intptr_t>(str.CharAt(0)) : -1;
     SetValue(instr, Smi::ZoneHandle(I, Smi::New(result)));
   }
 }
 
 
 
 
 void ConstantPropagator::VisitStringInterpolate(StringInterpolateInstr* instr) {
   SetValue(instr, non_constant_);
   return;
@@ skipping 10 matching lines @@
     if (!index_obj.IsSmi()) {
       // Should not occur.
       SetValue(instr, non_constant_);
       return;
     }
     const intptr_t index = Smi::Cast(index_obj).Value();
     if (index >= 0) {
       if (array_obj.IsString()) {
         const String& str = String::Cast(array_obj);
         if (str.Length() > index) {
-          SetValue(instr, Smi::Handle(I, Smi::New(str.CharAt(index))));
+          SetValue(instr, Smi::Handle(I,
+              Smi::New(static_cast<intptr_t>(str.CharAt(index)))));
           return;
         }
       } else if (array_obj.IsArray()) {
         const Array& a = Array::Cast(array_obj);
         if ((a.Length() > index) && a.IsImmutable()) {
           Instance& result = Instance::Handle(I);
           result ^= a.At(index);
           SetValue(instr, result);
           return;
         }
@@ skipping 2035 matching lines @@
 
   // Insert materializations at environment uses.
   for (intptr_t i = 0; i < exits_collector_.exits().length(); i++) {
     CreateMaterializationAt(
         exits_collector_.exits()[i], alloc, alloc->cls(), *slots);
   }
 }
 
 
 }  // namespace dart