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

src/mips/lithium-codegen-mips.cc

Index: src/mips/lithium-codegen-mips.cc
diff --git a/src/mips/lithium-codegen-mips.cc b/src/mips/lithium-codegen-mips.cc
index c32be4f35ca024d6b8abc2ca64b9c19e89ce1705..9b000781576de99779e2738f4f4eeadb0e7af3a7 100644
--- a/src/mips/lithium-codegen-mips.cc
+++ b/src/mips/lithium-codegen-mips.cc
@@ -1901,6 +1901,12 @@ void LCodeGen::DoBranch(LBranch* instr) {
         __ 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.
@@ -5771,6 +5777,13 @@ Condition LCodeGen::EmitTypeofIs(Label* true_label,
     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));
@@ -5814,20 +5827,10 @@ Condition LCodeGen::EmitTypeofIs(Label* true_label,
       __ 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,