compiler.cfg.instructions: forgot that ##box-displaced-alien needs a GC check; fixes segfault in benchmark.mandel

basis/compiler/cfg/instructions/instructions.factor

@@ -153,7 +153,12 @@ INSN: ##set-alien-double < ##alien-setter ;
 ! Memory allocation
 INSN: ##allot < ##flushable size class temp ;
 
-UNION: ##allocation ##allot ##box-float ##box-alien ##integer>bignum ;
+UNION: ##allocation
+##allot
+##box-float
+##box-alien
+##box-displaced-alien
+##integer>bignum ;
 
 INSN: ##write-barrier < ##effect card# table ;
 

basis/compiler/tests/codegen.factor

@@ -402,3 +402,9 @@ cell 4 = [
 
 [ 2 t ] [ 0 t global-dcn-bug-1 ] unit-test
 [ 1 f ] [ 0 f global-dcn-bug-1 ] unit-test
+
+! Forgot a GC check
+: missing-gc-check-1 ( a -- b ) { fixnum } declare <alien> ;
+: missing-gc-check-2 ( -- ) 10000000 [ missing-gc-check-1 drop ] each-integer ;
+
+[ ] [ missing-gc-check-2 ] unit-test