beam_reorder: Don't confuse beam_validator

Make sure we don't optimize code such as:

  is_tuple Fail Src
  test_arity Fail Src Arity
  get_tuple_element Src Pos Dst
  is_map Fail Src

If we would reorder the instructions like this:

  is_tuple Fail Src
  test_arity Fail Src Arity
  is_map Fail Src
  get_tuple_element Src Pos Dst

beam_validator would complain that the type for Src is a map
instead of a tuple. Since the code has problems to begin with,
there is no need to do the optimization.

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/compiler/src/beam_reorder.erl b/lib/compiler/src/beam_reorder.erl
index f1c0b3ef91..6a7c033ec6 100644
--- a/lib/compiler/src/beam_reorder.erl
+++ b/lib/compiler/src/beam_reorder.erl
@@ -87,6 +87,15 @@ reorder_1([{test,_,_,_}=I,
     %% instruction between the test instruction and the select
     %% instruction.
     reorder_1(Is, D, [S,I|Acc]);
+reorder_1([{test,_,{f,_},[Src|_]}=I|Is], D,
+	  [{get_tuple_element,Src,_,_}|_]=Acc) ->
+    %% We want to avoid code that can confuse beam_validator such as:
+    %%   is_tuple Fail Src
+    %%   test_arity Fail Src Arity
+    %%   is_map Fail Src
+    %%   get_tuple_element Src Pos Dst
+    %% Therefore, don't reorder the instructions in such cases.
+    reorder_1(Is, D, [I|Acc]);
 reorder_1([{test,_,{f,L},Ss}=I|Is0], D0,
 	  [{get_tuple_element,_,_,El}=G|Acc0]=Acc) ->
     case member(El, Ss) of