Do not rely on code patching on DBC for lazy deoptimization.

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 1d73b6b92011594142bb95f3c69e3973ea702025..17b094b2c867b2eead4bde9cb2f6ecb56c429876 100644
--- a/runtime/vm/code_generator.cc
+++ b/runtime/vm/code_generator.cc
@@ -1935,30 +1935,6 @@ void DeoptimizeAt(const Code& optimized_code, StackFrame* frame) {
     function.SwitchToUnoptimizedCode();
   }
 
-#if defined(TARGET_ARCH_DBC)
-  const Instructions& instrs =
-      Instructions::Handle(zone, optimized_code.instructions());
-  {
-    WritableInstructionsScope writable(instrs.PayloadStart(), instrs.Size());
-    CodePatcher::InsertDeoptimizationCallAt(frame->pc());
-    if (FLAG_trace_patching) {
-      const String& name = String::Handle(function.name());
-      OS::PrintErr("InsertDeoptimizationCallAt: 0x%" Px " for %s\n",
-                   frame->pc(), name.ToCString());
-    }
-    const ExceptionHandlers& handlers =
-        ExceptionHandlers::Handle(zone, optimized_code.exception_handlers());
-    ExceptionHandlerInfo info;
-    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);
-      if (FLAG_trace_patching) {
-        OS::PrintErr("  at handler 0x%" Px "\n", patch_pc);
-      }
-    }
-  }
-#else  // !DBC
   if (frame->IsMarkedForLazyDeopt()) {
     // Deopt already scheduled.
     if (FLAG_trace_deoptimization) {
@@ -1982,7 +1958,6 @@ void DeoptimizeAt(const Code& optimized_code, StackFrame* frame) {
                 frame->fp(), deopt_pc);
     }
   }
-#endif  // !DBC
 
   // Mark code as dead (do not GC its embedded objects).
   optimized_code.set_is_alive(false);
@@ -2080,7 +2055,6 @@ DEFINE_LEAF_RUNTIME_ENTRY(intptr_t,
               is_lazy_deopt ? "lazy-deopt" : "");
   }
 
-#if !defined(TARGET_ARCH_DBC)
   if (is_lazy_deopt) {
     uword deopt_pc = isolate->FindPendingDeopt(caller_frame->fp());
     if (FLAG_trace_deoptimization) {
@@ -2091,6 +2065,7 @@ DEFINE_LEAF_RUNTIME_ENTRY(intptr_t,
     // N.B.: Update frame before updating pending deopt table. The profiler
     // may attempt a stack walk in between.
     caller_frame->set_pc(deopt_pc);
+    ASSERT(!caller_frame->IsMarkedForLazyDeopt());
     ASSERT(caller_frame->pc() == deopt_pc);
     ASSERT(optimized_code.ContainsInstructionAt(caller_frame->pc()));
     isolate->ClearPendingDeoptsAtOrBelow(caller_frame->fp());
@@ -2100,7 +2075,6 @@ DEFINE_LEAF_RUNTIME_ENTRY(intptr_t,
                 caller_frame->pc());
     }
   }
-#endif  // !DBC
 
   // Copy the saved registers from the stack.
   fpu_register_t* fpu_registers;