[compiler] Remove support for concurrent OSR.

src/full-codegen/x64/full-codegen-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/ast/scopes.h"
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 3978 matching lines @@
   switch (target_state) {
     case INTERRUPT:
       //     sub <profiling_counter>, <delta>  ;; Not changed
       //     jns ok
       //     call <interrupt stub>
       //   ok:
       *jns_instr_address = kJnsInstruction;
       *jns_offset_address = kJnsOffset;
       break;
     case ON_STACK_REPLACEMENT:
-    case OSR_AFTER_STACK_CHECK:
       //     sub <profiling_counter>, <delta>  ;; Not changed
       //     nop
       //     nop
       //     call <on-stack replacment>
       //   ok:
       *jns_instr_address = kNopByteOne;
       *jns_offset_address = kNopByteTwo;
       break;
   }
 
@@ skipping 17 matching lines @@
     DCHECK_EQ(kJnsOffset, *(call_target_address - 2));
     DCHECK_EQ(isolate->builtins()->InterruptCheck()->entry(),
               Assembler::target_address_at(call_target_address,
                                            unoptimized_code));
     return INTERRUPT;
   }
 
   DCHECK_EQ(kNopByteOne, *jns_instr_address);
   DCHECK_EQ(kNopByteTwo, *(call_target_address - 2));
 
-  if (Assembler::target_address_at(call_target_address,
-                                   unoptimized_code) ==
-      isolate->builtins()->OnStackReplacement()->entry()) {
-    return ON_STACK_REPLACEMENT;
-  }
-
-  DCHECK_EQ(isolate->builtins()->OsrAfterStackCheck()->entry(),
-            Assembler::target_address_at(call_target_address,
-                                         unoptimized_code));
-  return OSR_AFTER_STACK_CHECK;
+  DCHECK_EQ(
+      isolate->builtins()->OnStackReplacement()->entry(),
+      Assembler::target_address_at(call_target_address, unoptimized_code));
+  return ON_STACK_REPLACEMENT;
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64