erts: Make re copy small subbinaries

Because small subbinaries can be converted to heapbinaries
during GC, we do not want to have references to those in the
re state, so we copy any binary that is small enough to fit
on the heap.

Closes #5150

1 files changed, 5 insertions, 2 deletions

diff --git a/erts/emulator/beam/erl_bif_re.c b/erts/emulator/beam/erl_bif_re.c
index bbc64eb9aa..f990a99547 100644
--- a/erts/emulator/beam/erl_bif_re.c
+++ b/erts/emulator/beam/erl_bif_re.c
@@ -1292,7 +1292,7 @@ re_run(Process *p, Eterm arg1, Eterm arg2, Eterm arg3)
     }
 
     /*  Optimized - if already in binary off heap, keep that and avoid
-       copying, also binary returns can be sub binaries in that case */
+        copying, also binary returns can be sub binaries in that case. */
 
     restart.flags = 0;
     if (is_binary(arg1)) {
@@ -1307,7 +1307,10 @@ re_run(Process *p, Eterm arg1, Eterm arg2, Eterm arg3)
 
 	slength = binary_size(arg1);
 	bptr = binary_val(real_bin);
-	if (bitsize != 0 || bitoffs != 0 ||  (*bptr != HEADER_PROC_BIN)) {
+	if (bitsize != 0 || bitoffs != 0 || slength <= ERL_ONHEAP_BIN_LIMIT) {
+            /* If this is an unaligned subbinary,
+               or the binary is smaller than the ERL_ONHEAP_BIN_LIMIT
+               we make a copy of the binary. */
 	    goto handle_iolist;
 	}
 	pb = (ProcBin *) bptr;