Allow invalidation and recompilation of instance allocation stubs. Requested in order to implement…

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 376 matching lines @@
   __ popl(EAX);  // Get Code object.
   __ popl(EDX);  // Restore arguments descriptor array.
   __ movl(EAX, FieldAddress(EAX, Code::instructions_offset()));
   __ addl(EAX, Immediate(Instructions::HeaderSize() - kHeapObjectTag));
   __ LeaveFrame();
   __ jmp(EAX);
   __ int3();
 }
 
 
+// Called from object allocate instruction when the allocation stub has been
+// disabled.
+void StubCode::GenerateFixAllocationStubTargetStub(Assembler* assembler) {
+  const Immediate& raw_null =
+      Immediate(reinterpret_cast<intptr_t>(Object::null()));
+  __ EnterStubFrame();
+  __ pushl(raw_null);  // Setup space on stack for return value.
+  __ CallRuntime(kFixAllocationStubTargetRuntimeEntry, 0);
+  __ popl(EAX);  // Get Code object.
+  __ movl(EAX, FieldAddress(EAX, Code::instructions_offset()));
+  __ addl(EAX, Immediate(Instructions::HeaderSize() - kHeapObjectTag));
+  __ LeaveFrame();
+  __ jmp(EAX);
+  __ int3();
+}
+
+
 // Input parameters:
 //   EDX: smi-tagged argument count, may be zero.
 //   EBP[kParamEndSlotFromFp + 1]: last argument.
 // Uses EAX, EBX, ECX, EDX.
 static void PushArgumentsArray(Assembler* assembler) {
   const Immediate& raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
   StubCode* stub_code = Isolate::Current()->stub_code();
 
   // Allocate array to store arguments of caller.
@@ skipping 662 matching lines @@
   __ LeaveCallRuntimeFrame();
   __ ret();
 }
 
 
 // Called for inline allocation of objects.
 // Input parameters:
 //   ESP + 4 : type arguments object (only if class is parameterized).
 //   ESP : points to return address.
 // Uses EAX, EBX, ECX, EDX, EDI as temporary registers.
-void StubCode::GenerateAllocationStubForClass(Assembler* assembler,
-                                              const Class& cls) {
+// Returns patch_code_pc offset where patching code for disabling the stub
+// has been generated (similar to regularly generated Dart code).
+uword StubCode::GenerateAllocationStubForClass(Assembler* assembler,
+                                               const Class& cls) {
   const intptr_t kObjectTypeArgumentsOffset = 1 * kWordSize;
   const Immediate& raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
   // The generated code is different if the class is parameterized.
   const bool is_cls_parameterized = cls.NumTypeArguments() > 0;
   ASSERT(!is_cls_parameterized ||
          (cls.type_arguments_field_offset() != Class::kNoTypeArguments));
   // kInlineInstanceSize is a constant used as a threshold for determining
   // when the object initialization should be done as a loop or as
   // straight line code.
@@ skipping 92 matching lines @@
     __ pushl(raw_null);  // Push null type arguments.
   }
   __ CallRuntime(kAllocateObjectRuntimeEntry, 2);  // Allocate object.
   __ popl(EAX);  // Pop argument (type arguments of object).
   __ popl(EAX);  // Pop argument (class of object).
   __ popl(EAX);  // Pop result (newly allocated object).
   // EAX: new object
   // Restore the frame pointer.
   __ LeaveFrame();
   __ ret();
+  // Emit function patching code. This will be swapped with the first 5 bytes
+  // at entry point.
+  uword patch_code_pc_offset = assembler->CodeSize();
+  StubCode* stub_code = Isolate::Current()->stub_code();
+  __ jmp(&stub_code->FixAllocationStubTargetLabel());
+  return patch_code_pc_offset;
 }
 
 
 // Called for invoking "dynamic noSuchMethod(Invocation invocation)" function
 // from the entry code of a dart function after an error in passed argument
 // name or number is detected.
 // Input parameters:
 //   ESP : points to return address.
 //   ESP + 4 : address of last argument.
 //   EDX : arguments descriptor array.
@@ skipping 824 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