Reapply "Lazy deopt without code patching."

runtime/vm/code_generator.cc

Index: runtime/vm/code_generator.cc
diff --git a/runtime/vm/code_generator.cc b/runtime/vm/code_generator.cc
index 6bfbdb8158e818cc13aa4517f7602d438c824626..e5a5c55259e65e3282b6055fd42e1515602d0a27 100644
--- a/runtime/vm/code_generator.cc
+++ b/runtime/vm/code_generator.cc
@@ -1996,15 +1996,10 @@ DEOPT_REASONS(DEOPT_REASON_TO_TEXT)
 }
 
 
-void DeoptimizeAt(const Code& optimized_code, uword pc) {
+void DeoptimizeAt(const Code& optimized_code, StackFrame* frame) {
   ASSERT(optimized_code.is_optimized());
   Thread* thread = Thread::Current();
   Zone* zone = thread->zone();
-  ICData::DeoptReasonId deopt_reason = ICData::kDeoptUnknown;
-  uint32_t deopt_flags = 0;
-  const TypedData& deopt_info = TypedData::Handle(zone,
-      optimized_code.GetDeoptInfoAtPc(pc, &deopt_reason, &deopt_flags));
-  ASSERT(!deopt_info.IsNull());
   const Function& function = Function::Handle(zone, optimized_code.function());
   const Error& error =
       Error::Handle(zone, Compiler::EnsureUnoptimizedCode(thread, function));
@@ -2018,24 +2013,18 @@ void DeoptimizeAt(const Code& optimized_code, uword pc) {
   if (function.HasOptimizedCode()) {
     function.SwitchToUnoptimizedCode();
   }
-  // Patch call site (lazy deoptimization is quite rare, patching it twice
-  // is not a performance issue).
-  uword lazy_deopt_jump_return = optimized_code.GetLazyDeoptReturnPc();
-  uword lazy_deopt_jump_throw = optimized_code.GetLazyDeoptThrowPc();
-#if !defined(TARGET_ARCH_DBC)
-  ASSERT(lazy_deopt_jump_return != 0);
-  ASSERT(lazy_deopt_jump_throw != 0);
-#endif
+
+#if defined(TARGET_ARCH_DBC)
   const Instructions& instrs =
       Instructions::Handle(zone, optimized_code.instructions());
   {
     WritableInstructionsScope writable(instrs.PayloadStart(), instrs.size());
-    CodePatcher::InsertDeoptimizationCallAt(pc, lazy_deopt_jump_return);
+    CodePatcher::InsertDeoptimizationCallAt(frame->pc());
     if (FLAG_trace_patching) {
       const String& name = String::Handle(function.name());
       OS::PrintErr(
-          "InsertDeoptimizationCallAt: 0x%" Px " to 0x%" Px " for %s\n",
-          pc, lazy_deopt_jump_return, name.ToCString());
+          "InsertDeoptimizationCallAt: 0x%" Px " for %s\n",
+          frame->pc(), name.ToCString());
     }
     const ExceptionHandlers& handlers =
         ExceptionHandlers::Handle(zone, optimized_code.exception_handlers());
@@ -2043,12 +2032,34 @@ void DeoptimizeAt(const Code& optimized_code, uword pc) {
     for (intptr_t i = 0; i < handlers.num_entries(); ++i) {
       handlers.GetHandlerInfo(i, &info);
       const uword patch_pc = instrs.PayloadStart() + info.handler_pc_offset;
-      CodePatcher::InsertDeoptimizationCallAt(patch_pc, lazy_deopt_jump_throw);
+      CodePatcher::InsertDeoptimizationCallAt(patch_pc);
       if (FLAG_trace_patching) {
         OS::PrintErr("  at handler 0x%" Px "\n", patch_pc);
       }
     }
   }
+#else  // !DBC
+  uword lazy_deopt_entry =
+      StubCode::DeoptimizeLazyFromReturn_entry()->EntryPoint();
+  if (frame->pc() == lazy_deopt_entry) {
+    // Deopt already scheduled.
+    if (FLAG_trace_deoptimization) {
+      THR_Print("Lazy deopt already scheduled for fp=%" Pp "\n", frame->fp());
+    }
+  } else {
+    uword deopt_pc = frame->pc();
+    ASSERT(optimized_code.ContainsInstructionAt(deopt_pc));
+    PendingLazyDeopt pair(frame->fp(), deopt_pc);
+    thread->isolate()->pending_deopts()->Add(pair);
+    frame->set_pc(lazy_deopt_entry);
+
+    if (FLAG_trace_deoptimization) {
+      THR_Print("Lazy deopt scheduled for fp=%" Pp ", pc=%" Pp "\n",
+                frame->fp(), deopt_pc);
+    }
+  }
+#endif  // !DBC
+
   // Mark code as dead (do not GC its embedded objects).
   optimized_code.set_is_alive(false);
 }
@@ -2063,7 +2074,7 @@ void DeoptimizeFunctionsOnStack() {
   while (frame != NULL) {
     optimized_code = frame->LookupDartCode();
     if (optimized_code.is_optimized()) {
-      DeoptimizeAt(optimized_code, frame->pc());
+      DeoptimizeAt(optimized_code, frame);
     }
     frame = iterator.NextFrame();
   }
@@ -2144,6 +2155,40 @@ DEFINE_LEAF_RUNTIME_ENTRY(intptr_t, DeoptimizeCopyFrame,
        is_lazy_deopt ? "lazy-deopt" : "");
   }
 
+#if !defined(TARGET_ARCH_DBC)
+  if (is_lazy_deopt) {
+    uword deopt_pc = 0;
+    MallocGrowableArray<PendingLazyDeopt>* pending_deopts =
+        isolate->pending_deopts();
+    for (intptr_t i = pending_deopts->length() - 1; i >= 0; i--) {
+      if ((*pending_deopts)[i].fp() == caller_frame->fp()) {
+        deopt_pc = (*pending_deopts)[i].pc();
+        break;
+      }
+    }
+    for (intptr_t i = pending_deopts->length() - 1; i >= 0; i--) {
+      if ((*pending_deopts)[i].fp() <= caller_frame->fp()) {
+        pending_deopts->RemoveAt(i);
+      }
+    }
+    if (FLAG_trace_deoptimization) {
+      THR_Print("Lazy deopt fp=%" Pp " pc=%" Pp "\n",
+                caller_frame->fp(), deopt_pc);
+      THR_Print("%" Pd " pending lazy deopts\n",
+                pending_deopts->length());
+    }
+    ASSERT(deopt_pc != 0);
+    caller_frame->set_pc(deopt_pc);
+    ASSERT(caller_frame->pc() == deopt_pc);
+    ASSERT(optimized_code.ContainsInstructionAt(caller_frame->pc()));
+  } else {
+    if (FLAG_trace_deoptimization) {
+      THR_Print("Eager deopt fp=%" Pp " pc=%" Pp "\n",
+                caller_frame->fp(), caller_frame->pc());
+    }
+  }
+#endif  // !DBC
+
   // Copy the saved registers from the stack.
   fpu_register_t* fpu_registers;
   intptr_t* cpu_registers;
@@ -2204,6 +2249,7 @@ DEFINE_LEAF_RUNTIME_ENTRY(void, DeoptimizeFillFrame, 1, uword last_fp) {
 
   deopt_context->set_dest_frame(caller_frame);
   deopt_context->FillDestFrame();
+
 #else
   UNREACHABLE();
 #endif  // !DART_PRECOMPILED_RUNTIME