Cache lookups at megamorphic call sites in optimized code.

runtime/vm/stub_code_ia32.cc

 // Copyright (c) 2012, 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/assembler_macros.h"
 #include "vm/compiler.h"
@@ skipping 550 matching lines @@
   __ pushl(EBX);
   GenerateDeoptimizationSequence(assembler, true);  // Preserve EAX.
 }
 
 
 void StubCode::GenerateDeoptimizeStub(Assembler* assembler) {
   GenerateDeoptimizationSequence(assembler, false);  // Don't preserve EAX.
 }
 
 
+void StubCode::GenerateMegamorphicMissStub(Assembler* assembler) {
+  AssemblerMacros::EnterStubFrame(assembler);
+  // Load the receiver into EAX.  The argument count in the arguments
+  // descriptor in EDX is a smi.
+  __ movl(EAX, FieldAddress(EDX, ArgumentsDescriptor::count_offset()));
+  // Two words (return addres, saved fp) in the stack above the last argument.
+  __ movl(EAX, Address(ESP, EAX, TIMES_2, 2 * kWordSize));
+  // Preserve IC data and arguments descriptor.
+  __ pushl(ECX);
+  __ pushl(EDX);
+
+  const Immediate raw_null =
+      Immediate(reinterpret_cast<intptr_t>(Instructions::null()));
+  __ pushl(raw_null);  // Space for the result of the runtime call.
+  __ pushl(EAX);  // Pass receiver.
+  __ pushl(ECX);  // Pass IC data.
+  __ pushl(EDX);  // Pass rguments descriptor.
+  __ CallRuntime(kMegamorphicCacheMissHandlerRuntimeEntry);
+  // Discard arguments.
+  __ popl(EAX);
+  __ popl(EAX);
+  __ popl(EAX);
+  __ popl(EAX);  // Return value from the runtime call (instructions).
+  __ popl(EDX);  // Restore arguments descriptor.
+  __ popl(ECX);  // Restore IC data.
+  __ LeaveFrame();
+
+  Label lookup;
+  __ cmpl(EAX, raw_null);
+  __ j(EQUAL, &lookup, Assembler::kNearJump);
+  __ addl(EAX, Immediate(Instructions::HeaderSize() - kHeapObjectTag));
+  __ jmp(EAX);
+
+  __ Bind(&lookup);
+  __ jmp(&StubCode::InstanceFunctionLookupLabel());
+}
+
+
 // Called for inline allocation of arrays.
 // Input parameters:
 //   EDX : Array length as Smi.
 //   ECX : array element type (either NULL or an instantiated type).
 // Uses EAX, EBX, ECX, EDI  as temporary registers.
 // NOTE: EDX cannot be clobbered here as the caller relies on it being saved.
 // The newly allocated object is returned in EAX.
 void StubCode::GenerateAllocateArrayStub(Assembler* assembler) {
   Label slow_case;
   const Immediate raw_null =
@@ skipping 1635 matching lines @@
   __ Bind(&done);
   __ popl(temp);
   __ popl(right);
   __ popl(left);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32