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-rw-r--r--erts/emulator/beam/beam_emu.c32
1 files changed, 32 insertions, 0 deletions
diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c
index 5b2f032afc..ee8ba54cb8 100644
--- a/erts/emulator/beam/beam_emu.c
+++ b/erts/emulator/beam/beam_emu.c
@@ -1539,6 +1539,10 @@ void process_main(void)
/*
* Skeleton for receive statement:
*
+ * recv_mark L1 Optional
+ * call make_ref/monitor Optional
+ * ...
+ * recv_set L1 Optional
* L1: <-------------------+
* <-----------+ |
* | |
@@ -1557,6 +1561,34 @@ void process_main(void)
*
*/
+ OpCase(recv_mark_f): {
+ /*
+ * Save the current position in message buffer and the
+ * the label for the loop_rec/2 instruction for the
+ * the receive statement.
+ */
+ c_p->msg.mark = (BeamInstr *) Arg(0);
+ c_p->msg.saved_last = c_p->msg.last;
+ Next(1);
+ }
+
+ OpCase(i_recv_set): {
+ /*
+ * If the mark is valid (points to the loop_rec/2
+ * instruction that follows), we know that the saved
+ * position points to the first message that could
+ * possibly be matched out.
+ *
+ * If the mark is invalid, we do nothing, meaning that
+ * we will look through all messages in the message queue.
+ */
+ if (c_p->msg.mark == (BeamInstr *) (I+1)) {
+ c_p->msg.save = c_p->msg.saved_last;
+ }
+ I++;
+ /* Fall through to the loop_rec/2 instruction */
+ }
+
/*
* Pick up the next message and place it in x(0).
* If no message, jump to a wait or wait_timeout instruction.