1 files changed, 52 insertions, 3 deletions

diff --git a/src/lj_trace.c b/src/lj_trace.c
index 4608f81f..a0ff8864 100644
--- a/src/lj_trace.c
+++ b/src/lj_trace.c
@@ -821,7 +821,7 @@ static void trace_exit_regs(lua_State *L, ExitState *ex)
 }
 #endif
 
-#ifdef EXITSTATE_PCREG
+#if defined(EXITSTATE_PCREG) || (LJ_UNWIND_JIT && !EXITTRACE_VMSTATE)
 /* Determine trace number from pc of exit instruction. */
 static TraceNo trace_exit_find(jit_State *J, MCode *pc)
 {
@@ -843,10 +843,18 @@ int LJ_FASTCALL lj_trace_exit(jit_State *J, void *exptr)
   lua_State *L = J->L;
   ExitState *ex = (ExitState *)exptr;
   ExitDataCP exd;
-  int errcode;
+  int errcode, exitcode = J->exitcode;
+  TValue exiterr;
   const BCIns *pc;
   void *cf;
   GCtrace *T;
+
+  setnilV(&exiterr);
+  if (exitcode) {  /* Trace unwound with error code. */
+    J->exitcode = 0;
+    copyTV(L, &exiterr, L->top-1);
+  }
+
 #ifdef EXITSTATE_PCREG
   J->parent = trace_exit_find(J, (MCode *)(intptr_t)ex->gpr[EXITSTATE_PCREG]);
 #endif
@@ -866,6 +874,8 @@ int LJ_FASTCALL lj_trace_exit(jit_State *J, void *exptr)
   if (errcode)
     return -errcode;  /* Return negated error code. */
 
+  if (exitcode) copyTV(L, L->top++, &exiterr);  /* Anchor the error object. */
+
   if (!(LJ_HASPROFILE && (G(L)->hookmask & HOOK_PROFILE)))
     lj_vmevent_send(L, TEXIT,
       lj_state_checkstack(L, 4+RID_NUM_GPR+RID_NUM_FPR+LUA_MINSTACK);
@@ -877,7 +887,9 @@ int LJ_FASTCALL lj_trace_exit(jit_State *J, void *exptr)
   pc = exd.pc;
   cf = cframe_raw(L->cframe);
   setcframe_pc(cf, pc);
-  if (LJ_HASPROFILE && (G(L)->hookmask & HOOK_PROFILE)) {
+  if (exitcode) {
+    return -exitcode;
+  } else if (LJ_HASPROFILE && (G(L)->hookmask & HOOK_PROFILE)) {
     /* Just exit to interpreter. */
   } else if (G(L)->gc.state == GCSatomic || G(L)->gc.state == GCSfinalize) {
     if (!(G(L)->hookmask & HOOK_GC))
@@ -915,4 +927,41 @@ int LJ_FASTCALL lj_trace_exit(jit_State *J, void *exptr)
   }
 }
 
+#if LJ_UNWIND_JIT
+/* Given an mcode address determine trace exit address for unwinding. */
+uintptr_t LJ_FASTCALL lj_trace_unwind(jit_State *J, uintptr_t addr, ExitNo *ep)
+{
+#if EXITTRACE_VMSTATE
+  TraceNo traceno = J2G(J)->vmstate;
+#else
+  TraceNo traceno = trace_exit_find(J, (MCode *)addr);
+#endif
+  GCtrace *T = traceref(J, traceno);
+  if (T
+#if EXITTRACE_VMSTATE
+      && addr >= (uintptr_t)T->mcode && addr < (uintptr_t)T->mcode + T->szmcode
+#endif
+     ) {
+    SnapShot *snap = T->snap;
+    SnapNo lo = 0, exitno = T->nsnap;
+    uintptr_t ofs = (uintptr_t)((MCode *)addr - T->mcode);  /* MCode units! */
+    /* Rightmost binary search for mcode offset to determine exit number. */
+    do {
+      SnapNo mid = (lo+exitno) >> 1;
+      if (ofs < snap[mid].mcofs) exitno = mid; else lo = mid + 1;
+    } while (lo < exitno);
+    exitno--;
+    *ep = exitno;
+#ifdef EXITSTUBS_PER_GROUP
+    return (uintptr_t)exitstub_addr(J, exitno);
+#else
+    return (uintptr_t)exitstub_trace_addr(T, exitno);
+#endif
+  }
+  /* Cannot correlate addr with trace/exit. This will be fatal. */
+  lj_assertJ(0, "bad exit pc");
+  return 0;
+}
+#endif
+
 #endif