compiler: Suppress bs_context_to_binary/1 for a literal operand

The inliner can cause illegal uses of the bs_context_to_binary/1
instruction, such as:

  bs_context_to_binary {literal,"string"}

or

  bs_context_to_binary {integer,1}

Remove the bs_context_to_binary/1 instruction if the operand
is not a register (it is clearly not needed).

1 files changed, 10 insertions, 1 deletions

diff --git a/lib/compiler/src/v3_codegen.erl b/lib/compiler/src/v3_codegen.erl
index 1f05b4f6b4..948937c438 100644
--- a/lib/compiler/src/v3_codegen.erl
+++ b/lib/compiler/src/v3_codegen.erl
@@ -1190,7 +1190,12 @@ trap_bif(_, _, _) -> false.
 
 bif_cg(bs_context_to_binary=Instr, [Src0], [], Le, Vdb, Bef, St0) ->
     [Src] = cg_reg_args([Src0], Bef),
-    {[{Instr,Src}],clear_dead(Bef, Le#l.i, Vdb), St0};
+    case is_register(Src) of
+	false ->
+	    {[],clear_dead(Bef, Le#l.i, Vdb), St0};
+	true ->
+	    {[{Instr,Src}],clear_dead(Bef, Le#l.i, Vdb), St0}
+    end;
 bif_cg(dsetelement, [Index0,Tuple0,New0], _Rs, Le, Vdb, Bef, St0) ->
     [New,Tuple,{integer,Index1}] = cg_reg_args([New0,Tuple0,Index0], Bef),
     Index = Index1-1,
@@ -2019,6 +2024,10 @@ fetch_stack(V, [_|Stk], I) -> fetch_stack(V, Stk, I+1).
 
 on_stack(V, Stk) -> keymember(V, 1, Stk).
 
+is_register({x,_}) -> true;
+is_register({yy,_}) -> true;
+is_register(_) -> false.
+
 %% put_catch(CatchTag, Stack) -> Stack'
 %% drop_catch(CatchTag, Stack) -> Stack'
 %%  Special interface for putting and removing catch tags, to ensure that