Add LoadTaggedClassIdMayBeSmi to assembly and improve performance of inline cache stubs.

runtime/vm/stub_code_ia32.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_IA32)
 
 #include "vm/assembler.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
@@ skipping 1303 matching lines @@
     __ CallRuntime(kSingleStepHandlerRuntimeEntry, 0);
     __ popl(ECX);
     __ LeaveFrame();
     __ Bind(&not_stepping);
   }
 
   // ECX: IC data object (preserved).
   // Load arguments descriptor into EDX.
   __ movl(EDX, FieldAddress(ECX, ICData::arguments_descriptor_offset()));
   // Loop that checks if there is an IC data match.
-  Label loop, update, test, found, get_class_id_as_smi;
+  Label loop, update, test, found;
   // ECX: IC data object (preserved).
   __ movl(EBX, FieldAddress(ECX, ICData::ic_data_offset()));
   // EBX: ic_data_array with check entries: classes and target functions.
   __ leal(EBX, FieldAddress(EBX, Array::data_offset()));
   // EBX: points directly to the first ic data array element.
 
   // Get the receiver's class ID (first read number of arguments from
   // arguments descriptor array and then access the receiver from the stack).
   __ movl(EAX, FieldAddress(EDX, ArgumentsDescriptor::count_offset()));
   __ movl(EAX, Address(ESP, EAX, TIMES_2, 0));  // EAX (argument_count) is smi.
-  __ call(&get_class_id_as_smi);
+  __ LoadTaggedClassIdMayBeSmi(EAX, EAX);
+
   // EAX: receiver's class ID (smi).
   __ movl(EDI, Address(EBX, 0));  // First class id (smi) to check.
   __ jmp(&test);
 
   __ Bind(&loop);
   for (int i = 0; i < num_args; i++) {
     if (i > 0) {
       // If not the first, load the next argument's class ID.
       __ movl(EAX, FieldAddress(EDX, ArgumentsDescriptor::count_offset()));
       __ movl(EAX, Address(ESP, EAX, TIMES_2, - i * kWordSize));
-      __ call(&get_class_id_as_smi);
+      __ LoadTaggedClassIdMayBeSmi(EAX, EAX);
+
       // EAX: next argument class ID (smi).
       __ movl(EDI, Address(EBX, i * kWordSize));
       // EDI: next class ID to check (smi).
     }
     __ cmpl(EAX, EDI);  // Class id match?
     if (i < (num_args - 1)) {
       __ j(NOT_EQUAL, &update);  // Continue.
     } else {
       // Last check, all checks before matched.
       __ j(EQUAL, &found, Assembler::kNearJump);  // Break.
     }
   }
   __ Bind(&update);
   // Reload receiver class ID.  It has not been destroyed when num_args == 1.
   if (num_args > 1) {
     __ movl(EAX, FieldAddress(EDX, ArgumentsDescriptor::count_offset()));
     __ movl(EAX, Address(ESP, EAX, TIMES_2, 0));
-    __ call(&get_class_id_as_smi);
+    __ LoadTaggedClassIdMayBeSmi(EAX, EAX);
   }
 
   const intptr_t entry_size = ICData::TestEntryLengthFor(num_args) * kWordSize;
   __ addl(EBX, Immediate(entry_size));  // Next entry.
   __ movl(EDI, Address(EBX, 0));  // Next class ID.
 
   __ Bind(&test);
   __ cmpl(EDI, Immediate(Smi::RawValue(kIllegalCid)));  // Done?
   __ j(NOT_EQUAL, &loop, Assembler::kNearJump);
 
@@ skipping 36 matching lines @@
   __ addl(Address(EBX, count_offset), Immediate(Smi::RawValue(1)));
   __ j(NO_OVERFLOW, &call_target_function, Assembler::kNearJump);
   __ movl(Address(EBX, count_offset),
           Immediate(Smi::RawValue(Smi::kMaxValue)));
 
   __ Bind(&call_target_function);
   // EAX: Target function.
   __ movl(EBX, FieldAddress(EAX, Function::instructions_offset()));
   __ addl(EBX, Immediate(Instructions::HeaderSize() - kHeapObjectTag));
   __ jmp(EBX);
-
-  // Instance in EAX, return its class-id in EAX as Smi.
-  __ Bind(&get_class_id_as_smi);
-  Label not_smi;
-  // Test if Smi -> load Smi class for comparison.
-  __ testl(EAX, Immediate(kSmiTagMask));
-  __ j(NOT_ZERO, &not_smi, Assembler::kNearJump);
-  __ movl(EAX, Immediate(Smi::RawValue(kSmiCid)));
-  __ ret();
-
-  __ Bind(&not_smi);
-  __ LoadClassId(EAX, EAX);
-  __ SmiTag(EAX);
-  __ ret();
+  __ int3();
 }
 
 
 // Use inline cache data array to invoke the target or continue in inline
 // cache miss handler. Stub for 1-argument check (receiver class).
 //  ECX: Inline cache data object.
 //  TOS(0): Return address.
 // Inline cache data object structure:
 // 0: function-name
 // 1: N, number of arguments checked.
@@ skipping 467 matching lines @@
   const Register temp = ECX;
   __ movl(left, Address(ESP, 2 * kWordSize));
   __ movl(right, Address(ESP, 1 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right, temp);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32