Remove debug stmts during grouping of switch.

Debug statements introduced during the translation result in warnings
when they are introduced at the head of the switch. Since they are
not used and the warning is not necessary we can remove them before.
Fix 17580.

3 files changed, 19 insertions, 7 deletions

diff --git a/cfrontend/C2C.ml b/cfrontend/C2C.ml
index a2db0915..913b2874 100644
--- a/cfrontend/C2C.ml
+++ b/cfrontend/C2C.ml
@@ -918,8 +918,11 @@ let rec groupSwitch = function
       let (fst, cases) = groupSwitch rem in
       (Cutil.sskip, (case, fst) :: cases)
   | Stmt s :: rem ->
-      let (fst, cases) = groupSwitch rem in
-      (Cutil.sseq s.sloc s fst, cases)
+      if Cutil.is_debug_stmt s then
+        groupSwitch rem
+      else
+        let (fst, cases) = groupSwitch rem in
+        (Cutil.sseq s.sloc s fst, cases)
 
 (* Test whether the statement contains case and give an *)
 let rec contains_case s =
@@ -1313,4 +1316,3 @@ let convertProgram p =
         if Cerrors.check_errors () then None else Some p'
   with Env.Error msg ->
     error (Env.error_message msg); None
-
diff --git a/cparser/Cutil.ml b/cparser/Cutil.ml
index a86c779f..1b0bf65d 100644
--- a/cparser/Cutil.ml
+++ b/cparser/Cutil.ml
@@ -880,6 +880,18 @@ let is_literal_0 e =
   | EConst(CInt(0L, _, _)) -> true
   | _ -> false
 
+(* Check that a C statement is a debug annotation *)
+
+let is_debug_stmt s =
+  let is_debug_call = function
+    | (ECall ({edesc = EVar id; _},_)) -> id.name = "__builtin_debug"
+    | _ -> false in
+  match s.sdesc with
+  | Sdo {edesc = e;_} ->
+      is_debug_call e
+  | _ -> false
+
+
 (* Assignment compatibility check over attributes.
    Standard attributes ("const", "volatile", "restrict") can safely
    be added (to the rhs type to get the lhs type) but must not be dropped.
@@ -1099,7 +1111,3 @@ let rec subst_stmt phi s =
                List.map subst_asm_operand inputs,
                clob)
   }
-
-
-
-
diff --git a/cparser/Cutil.mli b/cparser/Cutil.mli
index 8b6c609b..b353cba3 100644
--- a/cparser/Cutil.mli
+++ b/cparser/Cutil.mli
@@ -187,6 +187,8 @@ val type_of_member : Env.t -> field -> typ
   (* Return the type of accessing the given field [fld].
      Normally it's [fld.fld_type] but there is a special case for
      small unsigned bitfields. *)
+val is_debug_stmt : stmt -> bool
+  (* Is the given statement a call to debug builtin? *)
 val is_literal_0 : exp -> bool
   (* Is the given expression the integer literal "0"?  *)
 val is_lvalue : exp -> bool