Properly handle OOM in trace_save().

Thanks to Vyacheslav Egorov.

1 files changed, 12 insertions, 4 deletions

diff --git a/src/lj_trace.c b/src/lj_trace.c
index e51ec546..7d1b0936 100644
--- a/src/lj_trace.c
+++ b/src/lj_trace.c
@@ -117,15 +117,22 @@ static void perftools_addtrace(GCtrace *T)
 }
 #endif
 
-/* Save current trace by copying and compacting it. */
-static void trace_save(jit_State *J)
+/* Allocate space for copy of trace. */
+static GCtrace *trace_save_alloc(jit_State *J)
 {
   size_t sztr = ((sizeof(GCtrace)+7)&~7);
   size_t szins = (J->cur.nins-J->cur.nk)*sizeof(IRIns);
   size_t sz = sztr + szins +
               J->cur.nsnap*sizeof(SnapShot) +
               J->cur.nsnapmap*sizeof(SnapEntry);
-  GCtrace *T = lj_mem_newt(J->L, (MSize)sz, GCtrace);
+  return lj_mem_newt(J->L, (MSize)sz, GCtrace);
+}
+
+/* Save current trace by copying and compacting it. */
+static void trace_save(jit_State *J, GCtrace *T)
+{
+  size_t sztr = ((sizeof(GCtrace)+7)&~7);
+  size_t szins = (J->cur.nins-J->cur.nk)*sizeof(IRIns);
   char *p = (char *)T + sztr;
   memcpy(T, &J->cur, sizeof(GCtrace));
   setgcrefr(T->nextgc, J2G(J)->gc.root);
@@ -417,6 +424,7 @@ static void trace_stop(jit_State *J)
   BCOp op = bc_op(J->cur.startins);
   GCproto *pt = &gcref(J->cur.startpt)->pt;
   TraceNo traceno = J->cur.traceno;
+  GCtrace *T = trace_save_alloc(J);  /* Do this first. May throw OOM. */
   lua_State *L;
 
   switch (op) {
@@ -461,7 +469,7 @@ static void trace_stop(jit_State *J)
   /* Commit new mcode only after all patching is done. */
   lj_mcode_commit(J, J->cur.mcode);
   J->postproc = LJ_POST_NONE;
-  trace_save(J);
+  trace_save(J, T);
 
   L = J->L;
   lj_vmevent_send(L, TRACE,