MIPS: ES6 symbols: turn symbols into a proper primitive type

src/mips/lithium-codegen-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
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 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
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@@ skipping 1883 matching lines @@
         // String value -> false iff empty.
         Label not_string;
         __ lbu(at, FieldMemOperand(map, Map::kInstanceTypeOffset));
         __ Branch(&not_string, ge , at, Operand(FIRST_NONSTRING_TYPE));
         __ lw(at, FieldMemOperand(reg, String::kLengthOffset));
         __ Branch(true_label, ne, at, Operand(zero_reg));
         __ Branch(false_label);
         __ bind(&not_string);
       }
 
+      if (expected.Contains(ToBooleanStub::SYMBOL)) {
+        // Symbol value -> true.
+        __ lbu(at, FieldMemOperand(map, Map::kInstanceTypeOffset));
+        __ Branch(true_label, eq, at, Operand(SYMBOL_TYPE));

[Paul Lind, 2013/03/23 01:23:40]

We cannot use 'at' register in this Branch(), as 'at' will be used to hold the
Operand(SYMBOL_TYPE) in the 'eq' case.

I made a small change here to use scratch1().

[palfia, 2013/03/23 01:49:45]

Thanks for fixing this! It escaped my attention, that we cannot use 'at' with
'eq'.

+      }
+
       if (expected.Contains(ToBooleanStub::HEAP_NUMBER)) {
         CpuFeatureScope scope(masm(), FPU);
         // heap number -> false iff +0, -0, or NaN.
         DoubleRegister dbl_scratch = double_scratch0();
         Label not_heap_number;
         __ LoadRoot(at, Heap::kHeapNumberMapRootIndex);
         __ Branch(&not_heap_number, ne, map, Operand(at));
         __ ldc1(dbl_scratch, FieldMemOperand(reg, HeapNumber::kValueOffset));
         __ BranchF(true_label, false_label, ne, dbl_scratch, kDoubleRegZero);
         // Falls through if dbl_scratch == 0.
@@ skipping 3850 matching lines @@
     __ Branch(USE_DELAY_SLOT, false_label,
               ge, scratch, Operand(FIRST_NONSTRING_TYPE));
     // input is an object so we can load the BitFieldOffset even if we take the
     // other branch.
     __ lbu(at, FieldMemOperand(input, Map::kBitFieldOffset));
     __ And(at, at, 1 << Map::kIsUndetectable);
     cmp1 = at;
     cmp2 = Operand(zero_reg);
     final_branch_condition = eq;
 
+  } else if (type_name->Equals(heap()->symbol_string())) {
+    __ JumpIfSmi(input, false_label);
+    __ GetObjectType(input, input, scratch);
+    cmp1 = scratch;
+    cmp2 = Operand(SYMBOL_TYPE);
+    final_branch_condition = eq;
+
   } else if (type_name->Equals(heap()->boolean_string())) {
     __ LoadRoot(at, Heap::kTrueValueRootIndex);
     __ Branch(USE_DELAY_SLOT, true_label, eq, at, Operand(input));
     __ LoadRoot(at, Heap::kFalseValueRootIndex);
     cmp1 = at;
     cmp2 = Operand(input);
     final_branch_condition = eq;
 
   } else if (FLAG_harmony_typeof && type_name->Equals(heap()->null_string())) {
     __ LoadRoot(at, Heap::kNullValueRootIndex);
@@ skipping 23 matching lines @@
     cmp1 = input;
     cmp2 = Operand(JS_FUNCTION_PROXY_TYPE);
     final_branch_condition = eq;
 
   } else if (type_name->Equals(heap()->object_string())) {
     __ JumpIfSmi(input, false_label);
     if (!FLAG_harmony_typeof) {
       __ LoadRoot(at, Heap::kNullValueRootIndex);
       __ Branch(USE_DELAY_SLOT, true_label, eq, at, Operand(input));
     }
-    if (FLAG_harmony_symbols) {
-      // input is an object, it is safe to use GetObjectType in the delay slot.
-      __ GetObjectType(input, input, scratch);
-      __ Branch(USE_DELAY_SLOT, true_label, eq, scratch, Operand(SYMBOL_TYPE));
-      // Still an object, so the InstanceType can be loaded.
-      __ lbu(scratch, FieldMemOperand(input, Map::kInstanceTypeOffset));
-      __ Branch(USE_DELAY_SLOT, false_label,
-                lt, scratch, Operand(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
-    } else {
-      // input is an object, it is safe to use GetObjectType in the delay slot.
-      __ GetObjectType(input, input, scratch);
-      __ Branch(USE_DELAY_SLOT, false_label,
-                lt, scratch, Operand(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
-    }
+    // input is an object, it is safe to use GetObjectType in the delay slot.
+    __ GetObjectType(input, input, scratch);

[Paul Lind, 2013/03/22 22:15:20]

There is some tricky stuff with delay slots here that I'm not certain is still
justified, and I'm not sure the comments line up 100% with the code. I'm going
to suggest we land this, to fix the build for mips. But I'm going to raise an
issue to come back and refactor this a bit for clarity.

+    __ Branch(USE_DELAY_SLOT, false_label,
+              lt, scratch, Operand(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
     // Still an object, so the InstanceType can be loaded.
     __ lbu(scratch, FieldMemOperand(input, Map::kInstanceTypeOffset));
     __ Branch(USE_DELAY_SLOT, false_label,
               gt, scratch, Operand(LAST_NONCALLABLE_SPEC_OBJECT_TYPE));
     // Still an object, so the BitField can be loaded.
     // Check for undetectable objects => false.
     __ lbu(at, FieldMemOperand(input, Map::kBitFieldOffset));
     __ And(at, at, 1 << Map::kIsUndetectable);
     cmp1 = at;
     cmp2 = Operand(zero_reg);
@@ skipping 263 matching lines @@
   __ Subu(scratch, result, scratch);
   __ lw(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal