From 6bcdd45abd97134fddfb5b0307b1d256337b0c67 Mon Sep 17 00:00:00 2001
From: Rickard Green <rickard@erlang.org>
Date: Wed, 28 Dec 2016 18:23:06 +0100
Subject: Reduction counting on non-tail return

---
 erts/emulator/beam/beam_emu.c    | 21 +++++++++++++++++----
 erts/emulator/beam/erl_vm.h      |  2 +-
 erts/emulator/test/nif_SUITE.erl |  2 +-
 3 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c
index c554bd73b6..bb77dbd955 100644
--- a/erts/emulator/beam/beam_emu.c
+++ b/erts/emulator/beam/beam_emu.c
@@ -633,21 +633,34 @@ void** beam_ops;
       y[4] = xt4;				\
  } while (0)
 
+#define DispatchReturn                          \
+do {                                            \
+    if (FCALLS > 0 || FCALLS > neg_o_reds) {	\
+        FCALLS--;				\
+        Goto(*I);                               \
+    }                                           \
+    else {					\
+        c_p->current = NULL;                    \
+        c_p->arity = 1;                         \
+        goto context_switch3;			\
+    }						\
+} while (0)
+
 #define MoveReturn(Src)				\
     x(0) = (Src);				\
     I = c_p->cp;				\
     ASSERT(VALID_INSTR(*c_p->cp));		\
     c_p->cp = 0;				\
     CHECK_TERM(r(0));				\
-    Goto(*I)
+    DispatchReturn
 
 #define DeallocateReturn(Deallocate)       \
   do {                                     \
     int words_to_pop = (Deallocate);       \
-    SET_I((BeamInstr *) cp_val(*E));                     \
+    SET_I((BeamInstr *) cp_val(*E));       \
     E = ADD_BYTE_OFFSET(E, words_to_pop);  \
     CHECK_TERM(r(0));                      \
-    Goto(*I);                              \
+    DispatchReturn;                        \
   } while (0)
 
 #define MoveDeallocateReturn(Src, Deallocate)	\
@@ -1681,7 +1694,7 @@ void process_main(Eterm * x_reg_array, FloatDef* f_reg_array)
     c_p->cp = 0;
     CHECK_TERM(r(0));
     HEAP_SPACE_VERIFIED(0);
-    Goto(*I);
+    DispatchReturn;
  }
 
     /*
diff --git a/erts/emulator/beam/erl_vm.h b/erts/emulator/beam/erl_vm.h
index 93cfe08105..d88cafc5bf 100644
--- a/erts/emulator/beam/erl_vm.h
+++ b/erts/emulator/beam/erl_vm.h
@@ -36,7 +36,7 @@
 #define EMULATOR "BEAM"
 #define SEQ_TRACE 1
 
-#define CONTEXT_REDS 2000	/* Swap process out after this number */
+#define CONTEXT_REDS 4000	/* Swap process out after this number */
 #define MAX_ARG 255	        /* Max number of arguments allowed */
 #define MAX_REG 1024            /* Max number of x(N) registers used */
 
diff --git a/erts/emulator/test/nif_SUITE.erl b/erts/emulator/test/nif_SUITE.erl
index 0d3910b2e2..36d512e388 100644
--- a/erts/emulator/test/nif_SUITE.erl
+++ b/erts/emulator/test/nif_SUITE.erl
@@ -1689,7 +1689,7 @@ consume_timeslice(Config) when is_list(Config) ->
 
 consume_timeslice_test(Config) when is_list(Config) ->
     ensure_lib_loaded(Config),
-    CONTEXT_REDS = 2000,
+    CONTEXT_REDS = 4000,
     Me = self(),
     Go = make_ref(),
     RedDiff = make_ref(),
-- 
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