ARM: Support DoCheckInstanceType in lithium codegenerator.

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index bac1db4de3f0e09760ec109b86cb912a49c049e7..9670bbb9fb1a1325da72d6d6ce780860d410ee7a 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -2114,7 +2114,28 @@ void LCodeGen::DoCheckSmi(LCheckSmi* instr) {
 
 
 void LCodeGen::DoCheckInstanceType(LCheckInstanceType* instr) {
-  Abort("DoCheckInstanceType unimplemented.");
+  Register input = ToRegister(instr->input());
+  Register scratch = scratch0();

[Søren Thygesen Gjesse, 2011/01/05 20:52:36]

It is convenient to use ip as an intermediate register, but it can be unsafe, as
it is used extensively internally in both the assembler and macro assembler. It
is probably OK with the instructions used here, but is somebody where to later
change it things might break.

I think we should play it save and allocate a temporary for this instruction,
but I think it is not needed after all.

[Karl Klose, 2011/01/06 12:47:14]

I remove the second temporary and use only scratch0.

+  Register type = ip;
+  InstanceType first = instr->hydrogen()->first();
+  InstanceType last = instr->hydrogen()->last();
+
+  __ ldr(scratch, FieldMemOperand(input, HeapObject::kMapOffset));

[Søren Thygesen Gjesse, 2011/01/05 20:52:36]

Can't you just replace type with scratch here?

[Karl Klose, 2011/01/06 12:47:14]

Done.

+  __ ldrb(type, FieldMemOperand(scratch, Map::kInstanceTypeOffset));
+  __ cmp(type, Operand(first));
+
+  // If there is only one type in the interval check for equality.
+  if (first == last) {
+    DeoptimizeIf(ne, instr->environment());
+  } else {
+    DeoptimizeIf(lo, instr->environment());
+    // Omit check for the last type.
+    if (last != LAST_TYPE) {

[Søren Thygesen Gjesse, 2011/01/05 20:52:36]

No need to reload type - can stay in scratch.

[Karl Klose, 2011/01/06 12:47:14]

Done.

+      __ ldrb(type, FieldMemOperand(scratch, Map::kInstanceTypeOffset));
+      __ cmp(type, Operand(last));
+      DeoptimizeIf(hi, instr->environment());
+    }
+  }
 }