ARM: EmitNumberUntagD() Improvment

src/arm/lithium-codegen-arm.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 4853 matching lines @@
 
 void LCodeGen::EmitNumberUntagD(Register input_reg,
                                 DwVfpRegister result_reg,
                                 bool can_convert_undefined_to_nan,
                                 bool deoptimize_on_minus_zero,
                                 LEnvironment* env,
                                 NumberUntagDMode mode) {
   Register scratch = scratch0();
   SwVfpRegister flt_scratch = double_scratch0().low();
   ASSERT(!result_reg.is(double_scratch0()));
-
-  Label load_smi, heap_number, done;
-
+  Label convert, load_smi, done;
   if (mode == NUMBER_CANDIDATE_IS_ANY_TAGGED) {
     // Smi check.
     __ UntagAndJumpIfSmi(scratch, input_reg, &load_smi);
-
     // Heap number map check.
     __ ldr(scratch, FieldMemOperand(input_reg, HeapObject::kMapOffset));
     __ LoadRoot(ip, Heap::kHeapNumberMapRootIndex);
     __ cmp(scratch, Operand(ip));
-    if (!can_convert_undefined_to_nan) {
+    if (can_convert_undefined_to_nan) {
+      __ b(ne, &convert);
+    } else {
       DeoptimizeIf(ne, env);
-    } else {
-      Label heap_number, convert;
-      __ b(eq, &heap_number);
-
-      // Convert undefined (and hole) to NaN.
-      __ LoadRoot(ip, Heap::kUndefinedValueRootIndex);
-      __ cmp(input_reg, Operand(ip));
-      DeoptimizeIf(ne, env);
-
-      __ bind(&convert);
-      __ LoadRoot(scratch, Heap::kNanValueRootIndex);
-      __ vldr(result_reg, scratch, HeapNumber::kValueOffset - kHeapObjectTag);
-      __ jmp(&done);
-
-      __ bind(&heap_number);
     }
-    // Heap number to double register conversion.
+    // load heap number
     __ vldr(result_reg, input_reg, HeapNumber::kValueOffset - kHeapObjectTag);
     if (deoptimize_on_minus_zero) {
       __ VmovLow(scratch, result_reg);
       __ cmp(scratch, Operand::Zero());
       __ b(ne, &done);
       __ VmovHigh(scratch, result_reg);
       __ cmp(scratch, Operand(HeapNumber::kSignMask));
       DeoptimizeIf(eq, env);
     }
     __ jmp(&done);
+    if (can_convert_undefined_to_nan) {
+      __ bind(&convert);
+      // Convert undefined (and hole) to NaN.
+      __ LoadRoot(ip, Heap::kUndefinedValueRootIndex);
+      __ cmp(input_reg, Operand(ip));
+      DeoptimizeIf(ne, env);
+      __ LoadRoot(scratch, Heap::kNanValueRootIndex);
+      __ vldr(result_reg, scratch, HeapNumber::kValueOffset - kHeapObjectTag);
+      __ jmp(&done);
+    }
   } else {
     __ SmiUntag(scratch, input_reg);
     ASSERT(mode == NUMBER_CANDIDATE_IS_SMI);
   }
-
   // Smi to double register conversion
   __ bind(&load_smi);
   // scratch: untagged value of input_reg
   __ vmov(flt_scratch, scratch);
   __ vcvt_f64_s32(result_reg, flt_scratch);
   __ bind(&done);
 }
 
 
 void LCodeGen::DoDeferredTaggedToI(LTaggedToI* instr) {
@@ skipping 864 matching lines @@
   __ sub(scratch, result, Operand::PointerOffsetFromSmiKey(index));
   __ ldr(result, FieldMemOperand(scratch,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal