Implement correct semantics of Boolean Conversion

runtime/vm/intermediate_language_x64.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/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/dart_entry.h"
 #include "vm/flow_graph.h"
 #include "vm/flow_graph_compiler.h"
 #include "vm/flow_graph_range_analysis.h"
 #include "vm/locations.h"
 #include "vm/object_store.h"
 #include "vm/parser.h"
 #include "vm/stack_frame.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
 
 #define __ compiler->assembler()->
 
 namespace dart {
 
 DECLARE_FLAG(bool, emit_edge_counters);
+DECLARE_FLAG(bool, enable_asserts);
+DECLARE_FLAG(bool, enable_type_checks);
 DECLARE_FLAG(int, optimization_counter_threshold);
 DECLARE_FLAG(bool, propagate_ic_data);
 DECLARE_FLAG(bool, throw_on_javascript_int_overflow);
 DECLARE_FLAG(bool, use_osr);
 
 // Generic summary for call instructions that have all arguments pushed
 // on the stack and return the result in a fixed register RAX.
 LocationSummary* Instruction::MakeCallSummary(Isolate* isolate) {
   LocationSummary* result = new(isolate) LocationSummary(
       Isolate::Current(), 0, 0, LocationSummary::kCall);
@@ skipping 286 matching lines @@
 
 static void EmitAssertBoolean(Register reg,
                               intptr_t token_pos,
                               intptr_t deopt_id,
                               LocationSummary* locs,
                               FlowGraphCompiler* compiler) {
   // Check that the type of the value is allowed in conditional context.
   // Call the runtime if the object is not bool::true or bool::false.
   ASSERT(locs->always_calls());
   Label done;
-  __ CompareObject(reg, Bool::True(), PP);
-  __ j(EQUAL, &done, Assembler::kNearJump);
-  __ CompareObject(reg, Bool::False(), PP);
-  __ j(EQUAL, &done, Assembler::kNearJump);
+
+  if (FLAG_enable_type_checks) {
+    __ CompareObject(reg, Bool::True(), PP);
+    __ j(EQUAL, &done, Assembler::kNearJump);
+    __ CompareObject(reg, Bool::False(), PP);
+    __ j(EQUAL, &done, Assembler::kNearJump);
+  } else {
+    ASSERT(FLAG_enable_asserts);
+    __ CompareObject(reg, Object::null_instance(), PP);
+    __ j(NOT_EQUAL, &done, Assembler::kNearJump);
+  }
 
   __ pushq(reg);  // Push the source object.
   compiler->GenerateRuntimeCall(token_pos,
                                 deopt_id,
                                 kNonBoolTypeErrorRuntimeEntry,
                                 1,
                                 locs);
   // We should never return here.
   __ int3();
   __ Bind(&done);
@@ skipping 6044 matching lines @@
   __ movq(R10, Immediate(kInvalidObjectPointer));
   __ movq(RBX, Immediate(kInvalidObjectPointer));
 #endif
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64