Revise assertions and fix bug in the implementation of shifts

runtime/vm/intermediate_language.h

 // 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.
 
 #ifndef RUNTIME_VM_INTERMEDIATE_LANGUAGE_H_
 #define RUNTIME_VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/flags.h"
@@ skipping 7226 matching lines @@
         shift_range_(NULL) {
     ASSERT((op_kind == Token::kSHR) || (op_kind == Token::kSHL));
     if (FLAG_limit_ints_to_64_bits) {
       mark_truncating();
     }
   }
 
   Range* shift_range() const { return shift_range_; }
 
   virtual bool ComputeCanDeoptimize() const {
-    return has_shift_count_check() ||
+    return (!IsShiftCountInRange()) ||
            (can_overflow() && (op_kind() == Token::kSHL));
   }
 
   virtual Representation representation() const { return kUnboxedMint; }
 
   virtual Representation RequiredInputRepresentation(intptr_t idx) const {
     ASSERT((idx == 0) || (idx == 1));
     return (idx == 0) ? kUnboxedMint : kTagged;
   }
 
   virtual void InferRange(RangeAnalysis* analysis, Range* range);
   virtual CompileType ComputeType() const;
 
   DECLARE_INSTRUCTION(ShiftMintOp)
 
  private:
   static const intptr_t kMintShiftCountLimit = 63;
-  bool has_shift_count_check() const;
+
+  // Returns true if the shift amount is guranteed to be in
+  // [0..kMintShiftCountLimit] range.
+  bool IsShiftCountInRange() const;
 
   Range* shift_range_;
 
   DISALLOW_COPY_AND_ASSIGN(ShiftMintOpInstr);
 };
 
 
 // Handles only NEGATE.
 class UnaryDoubleOpInstr : public TemplateDefinition<1, NoThrow, Pure> {
  public:
@@ skipping 1006 matching lines @@
   LocationSummary* Name::MakeLocationSummary(Zone* zone, bool opt) const {     \
     UNIMPLEMENTED();                                                           \
     return NULL;                                                               \
   }                                                                            \
   void Name::EmitNativeCode(FlowGraphCompiler* compiler) { UNIMPLEMENTED(); }
 
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_INTERMEDIATE_LANGUAGE_H_