Fix handling of exception-raising specific operations during spilling

The ARM and ARM64 architectures have `Ishiftcheckbound` specific instructions
that can raise an Invalid_argument exception.  This exception can, in turn,
be handled in the same function (see PR#10339 for an example).

However, these specific instructions were not taken into account
during insertion of spill code in asmcomp/spill.ml.  The consequence
is a variable that is reloaded from stack in the exception handler,
yet has not been spilled to stack before.

This commit fixes the issue by using the recently-fixed
`Mach.operation_can_raise` predicate to handle operations during spill
code insertion, instead of an ad-hoc pattern-matching.

Fixes: PR#10339

backend/spill.ml

@@ -494,17 +494,13 @@ let rec spill :
       let before1 = Reg.diff_set_array after i.res in
       k (instr_cons i.desc i.arg i.res new_next)
         (Reg.add_set_array before1 i.res))
-  | Iop _ ->
+  | Iop op ->
     spill env i.next finally (fun new_next after ->
       let before1 = Reg.diff_set_array after i.res in
       let before =
-        match i.desc with
-          Iop Icall_ind | Iop(Icall_imm _) | Iop(Iextcall _) | Iop(Ialloc _)
-        | Iop(Iintop Icheckbound) | Iop(Iintop_imm(Icheckbound, _))
-        | Iop (Iprobe _) ->
-            Reg.Set.union before1 env.at_raise
-        | _ ->
-            before1 in
+        if operation_can_raise op
+        then Reg.Set.union before1 env.at_raise
+        else before1 in
       k (instr_cons_debug i.desc i.arg i.res i.dbg
                   (add_spills env (Reg.inter_set_array after i.res) new_next))
         before)

ocaml/asmcomp/spill.ml

@@ -301,17 +301,13 @@ let rec spill i finally =
       let before1 = Reg.diff_set_array after i.res in
       (instr_cons i.desc i.arg i.res new_next,
        Reg.add_set_array before1 i.res)
-  | Iop _ ->
+  | Iop op ->
       let (new_next, after) = spill i.next finally in
       let before1 = Reg.diff_set_array after i.res in
       let before =
-        match i.desc with
-          Iop(Icall_ind) | Iop(Icall_imm _) | Iop(Iextcall _) | Iop(Ialloc _)
-        | Iop (Iprobe _)
-        | Iop(Iintop (Icheckbound)) | Iop(Iintop_imm(Icheckbound, _)) ->
-            Reg.Set.union before1 !spill_at_raise
-        | _ ->
-            before1 in
+        if operation_can_raise op
+        then Reg.Set.union before1 !spill_at_raise
+        else before1 in
       (instr_cons_debug i.desc i.arg i.res i.dbg
                   (add_spills (Reg.inter_set_array after i.res) new_next),
        before)

ocaml/testsuite/tests/asmcomp/try_checkbound.ml

@@ -0,0 +1,12 @@
+(* TEST *)
+
+(* See PR#10339 *)
+
+let access (a: string array) n =
+  try
+    ignore (a.(n)); -1
+  with _ ->
+    n
+
+let _ =
+  assert (access [||] 1 = 1)