ARM: Support DoCheckInstanceType in lithium codegenerator.

src/arm/lithium-codegen-arm.cc

 // Copyright 2010 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 2096 matching lines @@
 
 void LCodeGen::DoCheckSmi(LCheckSmi* instr) {
   LOperand* input = instr->input();
   ASSERT(input->IsRegister());
   __ tst(ToRegister(input), Operand(kSmiTagMask));
   DeoptimizeIf(instr->condition(), instr->environment());
 }
 
 
 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());
+    }
+  }
 }
 
 
 void LCodeGen::DoCheckFunction(LCheckFunction* instr) {
   ASSERT(instr->input()->IsRegister());
   Register reg = ToRegister(instr->input());
   __ cmp(reg, Operand(instr->hydrogen()->target()));
   DeoptimizeIf(ne, instr->environment());
 }
 
@@ skipping 242 matching lines @@
 
 
 void LCodeGen::DoOsrEntry(LOsrEntry* instr) {
   Abort("DoOsrEntry unimplemented.");
 }
 
 
 #undef __
 
 } }  // namespace v8::internal