Added flag --inline_smi_string_hashcode and --inline_smi_string_hashcode_ratio to decide when/if sh…

runtime/vm/flow_graph_compiler_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"  // Needed here to get TARGET_ARCH_IA32.
 #if defined(TARGET_ARCH_IA32)
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/ast_printer.h"
@@ skipping 1285 matching lines @@
   const Array& arguments_descriptor =
       Array::ZoneHandle(zone(), ic_data.arguments_descriptor());
   ASSERT(!arguments_descriptor.IsNull() && (arguments_descriptor.Length() > 0));
   const MegamorphicCache& cache = MegamorphicCache::ZoneHandle(zone(),
       MegamorphicCacheTable::Lookup(isolate(), name, arguments_descriptor));
 
   __ Comment("MegamorphicCall");
   // Load receiver into EBX.
   __ movl(EBX, Address(ESP, (argument_count - 1) * kWordSize));
   Label done;
-  if (name.raw() == Symbols::hashCode().raw()) {
-    Label try_onebytestring, megamorphic_call;
+  if (ShouldInlineSmiStringHashCode(ic_data)) {
+    Label megamorphic_call;
     __ Comment("Inlined get:hashCode for Smi and OneByteString");
+    __ movl(EAX, EBX);  // Move Smi hashcode to EAX.

[zra, 2016/04/27 16:28:17]

Smi hash code looks really easy to calculate =) Have you tried always inlining
it? Why is inlining of Smi and String coupled like this?

[srdjan, 2016/04/27 18:10:22]

In order to get the cid we must check for Smi anyway. As you see. the hashcode
is almost free, so inlining it anyway. 
Added a TODO (elsewhere), to check for Smi hotness and emit Smi check only.
Maybe I'll have time to implement it in a next CL. Adding the check always would
increase code size unnecessarily.

     __ testl(EBX, Immediate(kSmiTagMask));
-    __ j(NOT_ZERO, &try_onebytestring, Assembler::kNearJump);  // Non-smi value.
-    __ movl(EAX, EBX);
-    __ jmp(&done, Assembler::kNearJump);
+    __ j(ZERO, &done, Assembler::kNearJump);  // It is Smi, we are done.
 
-    __ Bind(&try_onebytestring);
     __ CompareClassId(EBX, kOneByteStringCid, EAX);
     __ j(NOT_EQUAL, &megamorphic_call, Assembler::kNearJump);
     __ movl(EAX, FieldAddress(EBX, String::hash_offset()));
     __ cmpl(EAX, Immediate(0));
     __ j(NOT_EQUAL, &done, Assembler::kNearJump);
 
     __ Bind(&megamorphic_call);
     __ Comment("Slow case: megamorphic call");
   }
   __ LoadObject(ECX, cache);
@@ skipping 548 matching lines @@
   __ movups(reg, Address(ESP, 0));
   __ addl(ESP, Immediate(kFpuRegisterSize));
 }
 
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32