VM: Fix double comparisons using != and NaN in optimized code.

runtime/vm/flow_graph_compiler_mips.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_MIPS.
 #if defined(TARGET_ARCH_MIPS)
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/ast_printer.h"
@@ skipping 1692 matching lines @@
 
   // EmitBranchOnCondition expects ordering to be described by CMPRES1, CMPRES2.
   branch->EmitBranchOnCondition(this, EQ);
 }
 
 
 void FlowGraphCompiler::EmitDoubleCompareBool(Condition true_condition,
                                               FpuRegister left,
                                               FpuRegister right,
                                               Register result) {
-  Label done;
+  Label done, is_true;
+  Label* nan_label = (true_condition == NE) ? &is_true : &done;
   __ Comment("DoubleCompareBool");
   assembler()->LoadObject(result, Bool::False());
   assembler()->cund(left, right);
-  assembler()->bc1t(&done);
+  assembler()->bc1t(nan_label);
 
   switch (true_condition) {
     case EQ: assembler()->ceqd(left, right); break;
     case NE: assembler()->ceqd(left, right); break;
     case LT: assembler()->coltd(left, right); break;
     case LE: assembler()->coled(left, right); break;
     case GT: assembler()->coltd(right, left); break;
     case GE: assembler()->coled(right, left); break;
     default: {
       // Should only passing the above conditions to this function.
       UNREACHABLE();
       break;
     }
   }
 
   if (true_condition == NE) {
     assembler()->bc1t(&done);  // False is already in result.
   } else {
     assembler()->bc1f(&done);
   }
+  assembler()->Bind(&is_true);
   assembler()->LoadObject(result, Bool::True());
   assembler()->Bind(&done);
 }
 
 
 FieldAddress FlowGraphCompiler::ElementAddressForIntIndex(intptr_t cid,
                                                           intptr_t index_scale,
                                                           Register array,
                                                           intptr_t index) {
   UNREACHABLE();
@@ skipping 251 matching lines @@
   __ AddImmediate(SP, kDoubleSize);
 }
 
 
 #undef __
 
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_MIPS