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

runtime/vm/code_generator.cc

Index: runtime/vm/code_generator.cc
===================================================================
--- runtime/vm/code_generator.cc	(revision 40064)
+++ runtime/vm/code_generator.cc	(working copy)
@@ -1341,6 +1341,50 @@
 }
 
 
+// The caller tried to allocate an instance via an invalidated allocation
+// stub.
+DEFINE_RUNTIME_ENTRY(FixAllocationStubTarget, 0) {
+  StackFrameIterator iterator(StackFrameIterator::kDontValidateFrames);
+  StackFrame* frame = iterator.NextFrame();
+  while (frame != NULL && (frame->IsStubFrame() || frame->IsExitFrame())) {

[koda, 2014/09/10 15:33:21]

This explicit null-check looks strange, since null should not appear (and if it
does, the "->" deref would still crash immediately also in release mode).
Consider only having it ASSERTs (moving it into the loop+before).

[zra, 2014/09/10 16:07:39]

parens around (frame != NULL)

[srdjan, 2014/09/11 16:22:35]

Done, also for FixCallersTarget above.

[srdjan, 2014/09/11 16:22:36]

Removed that test

+    frame = iterator.NextFrame();
+  }
+  ASSERT(frame != NULL);
+  if (frame->IsEntryFrame()) {
+    // There must be a valid Dart frame.
+    UNREACHABLE();
+  }
+  ASSERT(frame->IsDartFrame());
+  const Code& caller_code = Code::Handle(isolate, frame->LookupDartCode());
+  ASSERT(!caller_code.IsNull());
+  const uword target =
+      CodePatcher::GetStaticCallTargetAt(frame->pc(), caller_code);
+  const Code& stub = Code::Handle(isolate, Code::LookupCode(target));
+  Class& alloc_class = Class::ZoneHandle(isolate);
+  alloc_class ^= stub.owner();
+  Code& alloc_stub = Code::Handle(isolate, alloc_class.allocation_stub());
+  if (alloc_stub.IsNull()) {
+    alloc_stub = isolate->stub_code()->GetAllocationStubForClass(alloc_class);
+    ASSERT(!CodePatcher::IsEntryPatched(alloc_stub));
+  }
+  const Instructions& instrs =
+      Instructions::Handle(isolate, caller_code.instructions());
+  {
+    WritableInstructionsScope writable(instrs.EntryPoint(), instrs.size());
+    CodePatcher::PatchStaticCallAt(frame->pc(),
+                                   caller_code,
+                                   alloc_stub.EntryPoint());
+  }
+  if (FLAG_trace_patching) {
+    OS::PrintErr("FixAllocationStubTarget: caller %#" Px " "
+        " -> %#" Px "\n",
+        frame->pc(),
+        alloc_stub.EntryPoint());
+  }
+  arguments.SetReturn(alloc_stub);
+}
+
+
 const char* DeoptReasonToCString(ICData::DeoptReasonId deopt_reason) {
   switch (deopt_reason) {
 #define DEOPT_REASON_TO_TEXT(name) case ICData::kDeopt##name: return #name;