Sergey,

This patch moves the aforementioned test to the <trace/wbarrier.lua>
test, with refactoring to restore the JIT engine and GC settings after
the test.

Part of tarantool/tarantool#9398
---

 test/LuaJIT-tests/misc/wbarrier_obar.lua | 22 -------------
 test/LuaJIT-tests/trace/wbarrier.lua     | 41 ++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 22 deletions(-)
 delete mode 100644 test/LuaJIT-tests/misc/wbarrier_obar.lua

diff --git a/test/LuaJIT-tests/misc/wbarrier_obar.lua b/test/LuaJIT-tests/misc/wbarrier_obar.lua
deleted file mode 100644
index 258db215..00000000
--- a/test/LuaJIT-tests/misc/wbarrier_obar.lua
+++ /dev/null
@@ -1,22 +0,0 @@
--- DSE of USTORE must eliminate OBAR, too.
-
-if jit and jit.opt then pcall(jit.opt.start, "-sink") end
-
-local f
-do
-  local x
-  f = function()
-    local y = 0
-    for i=1,10000 do
-      x = {1}
-      if y > 0 then end
-      x = 1
-    end
-  end
-end
-
-collectgarbage()
-collectgarbage("setstepmul", 1)
-collectgarbage("restart")
-f()
-
diff --git a/test/LuaJIT-tests/trace/wbarrier.lua b/test/LuaJIT-tests/trace/wbarrier.lua
index 625c0ff2..9c9c50af 100644
--- a/test/LuaJIT-tests/trace/wbarrier.lua
+++ b/test/LuaJIT-tests/trace/wbarrier.lua
@@ -1,3 +1,12 @@
+local function jit_opt_is_on(needed)
+  for _, opt in ipairs({jit.status()}) do
+    if opt == needed then
+      return true
+    end
+  end
+  return false
+end
+
 do --- TBAR for HSTORE.
   local t = {[0]={}}
   for i = 1, 1e5 do t[i] = {t[i - 1]} end
@@ -14,3 +23,35 @@ do --- OBAR for USTORE.
   end
   f()
 end
+
+do --- DSE of USTORE must eliminate OBAR too.
+  local need_restore_sink = false
+  if jit_opt_is_on("sink") then
+    need_restore_sink = true
+    jit.opt.start("-sink")
+  end
+
+  local f
+  do
+    local x
+    f = function()
+      local y = 0
+      for _ = 1, 10000 do
+        x = {1}
+        if y > 0 then end
+        x = 1
+      end
+    end
+  end
+
+  collectgarbage()
+  local oldstepmul = collectgarbage("setstepmul", 1)
+  collectgarbage("restart")
+
+  f()
+
+  collectgarbage("setstepmul", oldstepmul)
+  if need_restore_sink then
+    jit.opt.start("+sink")
+  end
+end