MIPS: Introduce %_IsMinusZero.

src/mips/full-codegen-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3115 matching lines @@
   __ JumpIfSmi(v0, if_false);
   __ GetObjectType(v0, a1, a2);
   PrepareForBailoutBeforeSplit(expr, true, if_true, if_false);
   __ Branch(if_true, eq, a2, Operand(JS_FUNCTION_TYPE));
   __ Branch(if_false);
 
   context()->Plug(if_true, if_false);
 }
 
 
+void FullCodeGenerator::EmitIsMinusZero(CallRuntime* expr) {
+  ZoneList<Expression*>* args = expr->arguments();
+  ASSERT(args->length() == 1);
+
+  VisitForAccumulatorValue(args->at(0));
+
+  Label materialize_true, materialize_false;
+  Label* if_true = NULL;
+  Label* if_false = NULL;
+  Label* fall_through = NULL;
+  context()->PrepareTest(&materialize_true, &materialize_false,
+                         &if_true, &if_false, &fall_through);
+
+  __ CheckMap(v0, a1, Heap::kHeapNumberMapRootIndex, if_false, DO_SMI_CHECK);
+  __ lw(a2, FieldMemOperand(v0, HeapNumber::kExponentOffset));
+  __ lw(a1, FieldMemOperand(v0, HeapNumber::kMantissaOffset));
+  __ li(t0, 0x80000000);
+  Label not_nan;
+  __ Branch(&not_nan, ne, a2, Operand(t0));
+  __ mov(t0, zero_reg);
+  __ mov(a2, a1);
+  __ bind(&not_nan);
+
+  PrepareForBailoutBeforeSplit(expr, true, if_true, if_false);
+  Split(eq, a2, Operand(t0), if_true, if_false, fall_through);
+
+  context()->Plug(if_true, if_false);
+}
+
+
 void FullCodeGenerator::EmitIsArray(CallRuntime* expr) {
   ZoneList<Expression*>* args = expr->arguments();
   ASSERT(args->length() == 1);
 
   VisitForAccumulatorValue(args->at(0));
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
   Label* fall_through = NULL;
@@ skipping 1850 matching lines @@
       Assembler::target_address_at(pc_immediate_load_address)) ==
          reinterpret_cast<uint32_t>(
              isolate->builtins()->OsrAfterStackCheck()->entry()));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS