[Tarantool-patches] [PATCH luajit] Respect jit.off() on pending trace exit.

[Sergey Kaplun]

From: Mike Pall <mike>

Thanks to Sergey Kaplun.

(cherry-picked from commit 7dbe545933485849977d50384f2f20f2cccf0cf9)

Before this commit, the JIT engine didn't check the status of JIT flags
when compiling the side trace. Hence, after calling `jit.off()` the side
traces are still recorded. This patch adds the aforementioned check.

Sergey Kaplun:
* added the description and the test for the problem

Part of tarantool/tarantool#9595
---

Branch: https://github.com/tarantool/luajit/tree/skaplun/lj-1134-hotside-jit-off
Tarantool PR: https://github.com/tarantool/tarantool/pull/9607
Related issues:
* https://github.com/tarantool/tarantool/issues/9595
* https://github.com/LuaJIT/LuaJIT/issues/1134

 src/lj_trace.c                                |  2 +-
 .../lj-1134-hotside-jit-off.test.lua          | 44 +++++++++++++++++++
 2 files changed, 45 insertions(+), 1 deletion(-)
 create mode 100644 test/tarantool-tests/lj-1134-hotside-jit-off.test.lua

diff --git a/src/lj_trace.c b/src/lj_trace.c
index 236e06a0..20014ecb 100644
--- a/src/lj_trace.c
+++ b/src/lj_trace.c
@@ -917,7 +917,7 @@ int LJ_FASTCALL lj_trace_exit(jit_State *J, void *exptr)
   } else if (G(L)->gc.state == GCSatomic || G(L)->gc.state == GCSfinalize) {
     if (!(G(L)->hookmask & HOOK_GC))
       lj_gc_step(L);  /* Exited because of GC: drive GC forward. */
-  } else {
+  } else if ((J->flags & JIT_F_ON)) {
     trace_hotside(J, pc);
   }
   if (bc_op(*pc) == BC_JLOOP) {
diff --git a/test/tarantool-tests/lj-1134-hotside-jit-off.test.lua b/test/tarantool-tests/lj-1134-hotside-jit-off.test.lua
new file mode 100644
index 00000000..cdee3eb2
--- /dev/null
+++ b/test/tarantool-tests/lj-1134-hotside-jit-off.test.lua
@@ -0,0 +1,44 @@
+local tap = require('tap')
+
+-- Test file to demonstrate the JIT misbehaviour, when the side
+-- trace is compiled after `jit.off()`.
+-- See also: https://github.com/LuaJIT/LuaJIT/issue/1134.
+
+local test = tap.test('lj-1134-hotside-jit-off'):skipcond({
+  ['Test requires JIT enabled'] = not jit.status(),
+  ['Disabled on *BSD due to #4819'] = jit.os == 'BSD',
+})
+
+local traceinfo = require('jit.util').traceinfo
+
+test:plan(1)
+
+local take_side
+local function trace()
+  -- luacheck: ignore
+  -- Branch for the side exit.
+  if take_side then end
+end
+
+-- Flush all possible traces.
+jit.flush()
+
+jit.opt.start('hotloop=1', 'hotexit=1')
+
+trace()
+trace()
+
+assert(traceinfo(1), 'root trace not compiled')
+
+-- Force trace exit.
+take_side = true
+
+jit.off()
+
+-- Attempt to compile a side trace.
+trace()
+trace()
+
+test:ok(not traceinfo(2), 'no side trace compiled')
+
+test:done(true)
-- 
2.43.0