AOT: Single target stub.

runtime/vm/stub_code_x64.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_X64)
 
 #include "vm/assembler.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
@@ skipping 2149 matching lines @@
   __ jmp(RCX);
 
   __ Bind(&miss);
   __ LoadIsolate(RAX);
   __ movq(CODE_REG, Address(RAX, Isolate::ic_miss_code_offset()));
   __ movq(RCX, FieldAddress(CODE_REG, Code::entry_point_offset()));
   __ jmp(RCX);
 }
 
 
+// Called from switchable IC calls.
+//  RDI: receiver
+//  RBX: SingleTargetCache
+// Passed to target::
+//  CODE_REG: target Code object
+void StubCode::GenerateSingleTargetCallStub(Assembler* assembler) {
+  __ NoMonomorphicCheckedEntry();
+
+  Label miss;
+  __ LoadClassIdMayBeSmi(RAX, RDI);
+  __ movq(R9, FieldAddress(RBX, SingleTargetCache::lower_limit_offset()));
+  __ movq(R10, FieldAddress(RBX, SingleTargetCache::upper_limit_offset()));
+  __ cmpq(RAX, R9);

[Florian Schneider, 2016/08/30 20:42:34]

Not sure if it's worth doing, but if upper_limit contains the difference between
the two (upper - lower), then you could do only one unsigned compare, like we do
for array bounds checks:

__ subq(RAX, R9);
__ cmpq(RAX, R10);
__ j(ABOVE, &miss);

[rmacnak, 2016/08/31 16:42:57]

I see -0.5% layout benchmark and +0.5% build benchmark, so I'll stick with base
and bound.

+  __ j(LESS, &miss, Assembler::kNearJump);
+  __ cmpq(RAX, R10);
+  __ j(GREATER, &miss, Assembler::kNearJump);
+  __ movq(RCX, FieldAddress(RBX, SingleTargetCache::entry_point_offset()));
+  __ movq(CODE_REG, FieldAddress(RBX, SingleTargetCache::target_offset()));
+  __ jmp(RCX);
+
+  __ Bind(&miss);
+  __ EnterStubFrame();
+  __ pushq(RDI);  // Preserve receiver.
+
+  __ PushObject(Object::null_object());  // Result.
+  __ pushq(RDI);                         // Arg0: Receiver
+  __ CallRuntime(kSingleTargetMissRuntimeEntry, 1);
+  __ popq(RBX);
+  __ popq(RBX);  // result = IC
+
+  __ popq(RDI);  // Restore receiver.
+  __ LeaveStubFrame();
+
+  __ movq(CODE_REG, Address(THR, Thread::ic_lookup_through_code_stub_offset()));
+  __ movq(RCX, FieldAddress(CODE_REG, Code::checked_entry_point_offset()));
+  __ jmp(RCX);
+}
+
+
 // Called from the monomorphic checked entry.
 //  RDI: receiver
 void StubCode::GenerateMonomorphicMissStub(Assembler* assembler) {
   __ EnterStubFrame();
   __ pushq(RDI);  // Preserve receiver.
 
   __ PushObject(Object::null_object());  // Result.
   __ pushq(RDI);                         // Arg0: Receiver
   __ CallRuntime(kMonomorphicMissRuntimeEntry, 1);
   __ popq(RBX);
   __ popq(RBX);  // result = IC
 
   __ popq(RDI);  // Restore receiver.
   __ LeaveStubFrame();
 
   __ movq(CODE_REG, Address(THR, Thread::ic_lookup_through_code_stub_offset()));
   __ movq(RCX, FieldAddress(CODE_REG, Code::checked_entry_point_offset()));
   __ jmp(RCX);
 }
 
 
 void StubCode::GenerateFrameAwaitingMaterializationStub(Assembler* assembler) {
   __ int3();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64