1 files changed, 23 insertions, 8 deletions

diff --git a/erts/emulator/beam/erl_io_queue.c b/erts/emulator/beam/erl_io_queue.c
index 945ee1b6b5..eb156cc578 100644
--- a/erts/emulator/beam/erl_io_queue.c
+++ b/erts/emulator/beam/erl_io_queue.c
@@ -801,12 +801,11 @@ static Eterm iol2v_make_sub_bin(iol2v_state_t *state, Eterm bin_term,
     ERTS_GET_REAL_BIN(bin_term, orig_pb_term,
         byte_offset, bit_offset, bit_size);
 
-    (void)bit_offset;
-    (void)bit_size;
+    ASSERT(bit_size == 0);
 
     sb->thing_word = HEADER_SUB_BIN;
+    sb->bitoffs = bit_offset;
     sb->bitsize = 0;
-    sb->bitoffs = 0;
     sb->orig = orig_pb_term;
     sb->is_writable = 0;
 
@@ -984,7 +983,7 @@ static int iol2v_append_binary(iol2v_state_t *state, Eterm bin_term) {
     parent_header = binary_val(parent_binary);
     binary_size = binary_size(bin_term);
 
-    if (bit_offset != 0 || bit_size != 0) {
+    if (bit_size != 0) {
         return 0;
     } else if (binary_size == 0) {
         state->bytereds_spent += 1;
@@ -1026,8 +1025,16 @@ static int iol2v_append_binary(iol2v_state_t *state, Eterm bin_term) {
          * then just copy it into the accumulator. */
         iol2v_expand_acc(state, binary_size);
 
-        sys_memcpy(&(state->acc)->orig_bytes[state->acc_size],
-            binary_data, binary_size);
+        if (ERTS_LIKELY(bit_offset == 0)) {
+            sys_memcpy(&(state->acc)->orig_bytes[state->acc_size],
+                binary_data, binary_size);
+        } else {
+            ASSERT(binary_size <= ERTS_UWORD_MAX / 8);
+
+            erts_copy_bits(binary_data, bit_offset, 1,
+                (byte*)&(state->acc)->orig_bytes[state->acc_size], 0, 1,
+                binary_size * 8);
+        }
 
         state->acc_size += binary_size;
     } else {
@@ -1038,8 +1045,16 @@ static int iol2v_append_binary(iol2v_state_t *state, Eterm bin_term) {
 
         iol2v_expand_acc(state, spill);
 
-        sys_memcpy(&(state->acc)->orig_bytes[state->acc_size],
-            binary_data, spill);
+        if (ERTS_LIKELY(bit_offset == 0)) {
+            sys_memcpy(&(state->acc)->orig_bytes[state->acc_size],
+                binary_data, spill);
+        } else {
+            ASSERT(binary_size <= ERTS_UWORD_MAX / 8);
+
+            erts_copy_bits(binary_data, bit_offset, 1,
+                (byte*)&(state->acc)->orig_bytes[state->acc_size], 0, 1,
+                spill * 8);
+        }
 
         state->acc_size += spill;