MIPS: Fix the hole loading optimization.

src/mips/lithium-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 4649 matching lines @@
 void LCodeGen::EmitNumberUntagD(Register input_reg,
                                 DoubleRegister result_reg,
                                 bool deoptimize_on_undefined,
                                 bool deoptimize_on_minus_zero,
                                 LEnvironment* env,
                                 NumberUntagDMode mode) {
   Register scratch = scratch0();
 
   Label load_smi, heap_number, done;
 
-  if (mode == NUMBER_CANDIDATE_IS_ANY_TAGGED) {
+  STATIC_ASSERT(NUMBER_CANDIDATE_IS_ANY_TAGGED_CONVERT_HOLE >
+                NUMBER_CANDIDATE_IS_ANY_TAGGED);
+  if (mode >= NUMBER_CANDIDATE_IS_ANY_TAGGED) {
     // Smi check.
     __ UntagAndJumpIfSmi(scratch, input_reg, &load_smi);
 
     // Heap number map check.
     __ lw(scratch, FieldMemOperand(input_reg, HeapObject::kMapOffset));
     __ LoadRoot(at, Heap::kHeapNumberMapRootIndex);
     if (deoptimize_on_undefined) {
       DeoptimizeIf(ne, env, scratch, Operand(at));
     } else {
-      Label heap_number;
+      Label heap_number, convert;
       __ Branch(&heap_number, eq, scratch, Operand(at));
 
+      // Convert undefined (and hole) to NaN.
       __ LoadRoot(at, Heap::kUndefinedValueRootIndex);
+      if (mode == NUMBER_CANDIDATE_IS_ANY_TAGGED_CONVERT_HOLE) {
+        __ Branch(&convert, eq, input_reg, Operand(at));
+        __ LoadRoot(at, Heap::kTheHoleValueRootIndex);
+      }
       DeoptimizeIf(ne, env, input_reg, Operand(at));
 
-      // Convert undefined to NaN.
+      __ bind(&convert);
       __ LoadRoot(at, Heap::kNanValueRootIndex);
       __ ldc1(result_reg, FieldMemOperand(at, HeapNumber::kValueOffset));
       __ Branch(&done);
 
       __ bind(&heap_number);
     }
     // Heap number to double register conversion.
     __ ldc1(result_reg, FieldMemOperand(input_reg, HeapNumber::kValueOffset));
     if (deoptimize_on_minus_zero) {
       __ mfc1(at, result_reg.low());
       __ Branch(&done, ne, at, Operand(zero_reg));
       __ mfc1(scratch, result_reg.high());
       DeoptimizeIf(eq, env, scratch, Operand(HeapNumber::kSignMask));
     }
     __ Branch(&done);
-  } else if (mode == NUMBER_CANDIDATE_IS_SMI_OR_HOLE) {
-    __ SmiUntag(scratch, input_reg);
-    DeoptimizeIf(Ugreater_equal, env, scratch, Operand(zero_reg));
-  } else if (mode == NUMBER_CANDIDATE_IS_SMI_CONVERT_HOLE) {
-    __ UntagAndJumpIfSmi(scratch, input_reg, &load_smi);
-    __ Move(result_reg,
-            FixedDoubleArray::hole_nan_as_double());
-    __ Branch(&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
   __ mtc1(scratch, result_reg);
   __ cvt_d_w(result_reg, result_reg);
@@ skipping 112 matching lines @@
   ASSERT(input->IsRegister());
   LOperand* result = instr->result();
   ASSERT(result->IsDoubleRegister());
 
   Register input_reg = ToRegister(input);
   DoubleRegister result_reg = ToDoubleRegister(result);
 
   NumberUntagDMode mode = NUMBER_CANDIDATE_IS_ANY_TAGGED;
   HValue* value = instr->hydrogen()->value();
   if (value->type().IsSmi()) {
-    if (value->IsLoadKeyed()) {
-      HLoadKeyed* load = HLoadKeyed::cast(value);
-      if (load->UsesMustHandleHole()) {
-        if (load->hole_mode() == ALLOW_RETURN_HOLE) {
-          mode = NUMBER_CANDIDATE_IS_SMI_CONVERT_HOLE;
-        } else {
-          mode = NUMBER_CANDIDATE_IS_SMI_OR_HOLE;
-        }
-      } else {
-        mode = NUMBER_CANDIDATE_IS_SMI;
+    mode = NUMBER_CANDIDATE_IS_SMI;
+  } else if (value->IsLoadKeyed()) {
+    HLoadKeyed* load = HLoadKeyed::cast(value);
+    if (load->UsesMustHandleHole()) {
+      if (load->hole_mode() == ALLOW_RETURN_HOLE) {
+        mode = NUMBER_CANDIDATE_IS_ANY_TAGGED_CONVERT_HOLE;
       }
-    } else {
-      mode = NUMBER_CANDIDATE_IS_SMI;
     }
   }
 
   EmitNumberUntagD(input_reg, result_reg,
                    instr->hydrogen()->deoptimize_on_undefined(),
                    instr->hydrogen()->deoptimize_on_minus_zero(),
                    instr->environment(),
                    mode);
 }
 
@@ skipping 880 matching lines @@
   __ Subu(scratch, result, scratch);
   __ lw(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal