Enable cfg invariants and dead trap handler elimination by default

Fail if any handlers are dead

Author: gretay-js

backend/cfg/cfg.ml

@@ -202,7 +202,9 @@ let remove_trap_instructions t removed_trap_handlers =
        remove a few pushtrap/poptrap. *)
     assert Config.flambda2;
     (* remove Lpushtrap and Lpoptrap instructions that refer to dead labels. *)
-    Label.Tbl.iter remove_trap_instr t.blocks)
+    Label.Tbl.iter remove_trap_instr t.blocks;
+    Misc.fatal_errorf "Cfg of %s had dead trap handlers %a\n" t.fun_name
+      Label.Set.print removed_trap_handlers)
 
 let remove_blocks t labels_to_remove =
   let removed_labels = ref Label.Set.empty in

driver/flambda_backend_flags.ml

@@ -15,7 +15,7 @@
 (**************************************************************************)
 let use_ocamlcfg = ref true             (* -[no-]ocamlcfg *)
 let dump_cfg = ref false                (* -dcfg *)
-let cfg_invariants = ref false          (* -dcfg-invariants *)
+let cfg_invariants = ref true          (* -dcfg-invariants *)
 let regalloc = ref ""                   (* -regalloc *)
 let regalloc_params = ref ([] : string list)  (* -regalloc-param *)
 let regalloc_validate = ref true        (* -[no-]regalloc-validate *)
@@ -32,7 +32,7 @@ let cfg_peephole_optimize = ref true    (* -[no-]cfg-peephole-optimize *)
 let cfg_stack_checks = ref true         (* -[no-]cfg-stack-check *)
 let cfg_stack_checks_threshold = ref 16384 (* -cfg-stack-threshold *)
 
-let cfg_eliminate_dead_trap_handlers = ref false  (* -cfg-eliminate-dead-trap-handlers *)
+let cfg_eliminate_dead_trap_handlers = ref true  (* -cfg-eliminate-dead-trap-handlers *)
 
 let reorder_blocks_random = ref None    (* -reorder-blocks-random seed *)
 let basic_block_sections = ref false    (* -basic-block-sections *)