gimplify.cc

  gimplify_ctxp->exit_label = saved_label;

  *expr_p = NULL;
  return GS_ALL_DONE;
}

/* Gimplify a statement list onto a sequence.  These may be created either
   by an enlightened front-end, or by shortcut_cond_expr.  */

static enum gimplify_status
gimplify_statement_list (tree *expr_p, gimple_seq *pre_p)
{
  tree temp = voidify_wrapper_expr (*expr_p, NULL);

  tree_stmt_iterator i = tsi_start (*expr_p);

  while (!tsi_end_p (i))
    {
      gimplify_stmt (tsi_stmt_ptr (i), pre_p);
      tsi_delink (&i);
    }

  if (temp)
    {
      *expr_p = temp;
      return GS_OK;
    }

  return GS_ALL_DONE;
}


/* Emit warning for the unreachable statment STMT if needed.
   Return the gimple itself when the warning is emitted, otherwise
   return NULL.  */
static gimple *
emit_warn_switch_unreachable (gimple *stmt)
{
  if (gimple_code (stmt) == GIMPLE_GOTO
      && TREE_CODE (gimple_goto_dest (stmt)) == LABEL_DECL
      && DECL_ARTIFICIAL (gimple_goto_dest (stmt)))
  /* Don't warn for compiler-generated gotos.  These occur
     in Duff's devices, for example.  */
    return NULL;
  else if ((flag_auto_var_init > AUTO_INIT_UNINITIALIZED)
	   && ((gimple_call_internal_p (stmt, IFN_DEFERRED_INIT))
		|| (gimple_call_builtin_p (stmt, BUILT_IN_CLEAR_PADDING)
		    && (bool) TREE_INT_CST_LOW (gimple_call_arg (stmt, 1)))
		|| (is_gimple_assign (stmt)
		    && gimple_assign_single_p (stmt)
		    && (TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME)
		    && gimple_call_internal_p (
			 SSA_NAME_DEF_STMT (gimple_assign_rhs1 (stmt)),
			 IFN_DEFERRED_INIT))))
  /* Don't warn for compiler-generated initializations for
     -ftrivial-auto-var-init.
     There are 3 cases:
	case 1: a call to .DEFERRED_INIT;
	case 2: a call to __builtin_clear_padding with the 2nd argument is
		present and non-zero;
	case 3: a gimple assign store right after the call to .DEFERRED_INIT
		that has the LHS of .DEFERRED_INIT as the RHS as following:
		  _1 = .DEFERRED_INIT (4, 2, &"i1"[0]);
		  i1 = _1.  */
    return NULL;
  else
    warning_at (gimple_location (stmt), OPT_Wswitch_unreachable,
		"statement will never be executed");
  return stmt;
}

/* Callback for walk_gimple_seq.  */

static tree
warn_switch_unreachable_and_auto_init_r (gimple_stmt_iterator *gsi_p,
					 bool *handled_ops_p,
					 struct walk_stmt_info *wi)
{
  gimple *stmt = gsi_stmt (*gsi_p);
  bool unreachable_issued = wi->info != NULL;

  *handled_ops_p = true;
  switch (gimple_code (stmt))
    {
    case GIMPLE_TRY:
      /* A compiler-generated cleanup or a user-written try block.
	 If it's empty, don't dive into it--that would result in
	 worse location info.  */
      if (gimple_try_eval (stmt) == NULL)
	{
	  if (warn_switch_unreachable && !unreachable_issued)
	    wi->info = emit_warn_switch_unreachable (stmt);

	  /* Stop when auto var init warning is not on.  */
	  if (!warn_trivial_auto_var_init)
	    return integer_zero_node;
	}
      /* Fall through.  */
    case GIMPLE_BIND:
    case GIMPLE_CATCH:
    case GIMPLE_EH_FILTER:
    case GIMPLE_TRANSACTION:
      /* Walk the sub-statements.  */
      *handled_ops_p = false;
      break;

    case GIMPLE_DEBUG:
      /* Ignore these.  We may generate them before declarations that
	 are never executed.  If there's something to warn about,
	 there will be non-debug stmts too, and we'll catch those.  */
      break;

    case GIMPLE_LABEL:
      /* Stop till the first Label.  */
      return integer_zero_node;
    case GIMPLE_CALL:
      if (gimple_call_internal_p (stmt, IFN_ASAN_MARK))
	{
	  *handled_ops_p = false;
	  break;
	}
      if (warn_trivial_auto_var_init
	  && flag_auto_var_init > AUTO_INIT_UNINITIALIZED
	  && gimple_call_internal_p (stmt, IFN_DEFERRED_INIT))
	{
	  /* Get the variable name from the 3rd argument of call.  */
	  tree var_name = gimple_call_arg (stmt, 2);
	  var_name = TREE_OPERAND (TREE_OPERAND (var_name, 0), 0);
	  const char *var_name_str = TREE_STRING_POINTER (var_name);

	  warning_at (gimple_location (stmt), OPT_Wtrivial_auto_var_init,
		      "%qs cannot be initialized with"
		      "%<-ftrivial-auto-var_init%>",
		      var_name_str);
	  break;
       }

      /* Fall through.  */
    default:
      /* check the first "real" statement (not a decl/lexical scope/...), issue
	 warning if needed.  */
      if (warn_switch_unreachable && !unreachable_issued)
	wi->info = emit_warn_switch_unreachable (stmt);
      /* Stop when auto var init warning is not on.  */
      if (!warn_trivial_auto_var_init)
	return integer_zero_node;
      break;
    }
  return NULL_TREE;
}


/* Possibly warn about unreachable statements between switch's controlling
   expression and the first case.  Also warn about -ftrivial-auto-var-init
   cannot initialize the auto variable under such situation.
   SEQ is the body of a switch expression.  */

static void
maybe_warn_switch_unreachable_and_auto_init (gimple_seq seq)
{
  if ((!warn_switch_unreachable && !warn_trivial_auto_var_init)
      /* This warning doesn't play well with Fortran when optimizations
	 are on.  */
      || lang_GNU_Fortran ()
      || seq == NULL)
    return;

  struct walk_stmt_info wi;

  memset (&wi, 0, sizeof (wi));
  walk_gimple_seq (seq, warn_switch_unreachable_and_auto_init_r, NULL, &wi);
}


/* A label entry that pairs label and a location.  */
struct label_entry
{
  tree label;
  location_t loc;
};

/* Find LABEL in vector of label entries VEC.  */

static struct label_entry *
find_label_entry (const auto_vec<struct label_entry> *vec, tree label)
{
  unsigned int i;
  struct label_entry *l;

  FOR_EACH_VEC_ELT (*vec, i, l)
    if (l->label == label)
      return l;
  return NULL;
}

/* Return true if LABEL, a LABEL_DECL, represents a case label
   in a vector of labels CASES.  */

static bool
case_label_p (const vec<tree> *cases, tree label)
{
  unsigned int i;
  tree l;

  FOR_EACH_VEC_ELT (*cases, i, l)
    if (CASE_LABEL (l) == label)
      return true;
  return false;
}

/* Find the last nondebug statement in a scope STMT.  */

static gimple *
last_stmt_in_scope (gimple *stmt)
{
  if (!stmt)
    return NULL;

  switch (gimple_code (stmt))
    {
    case GIMPLE_BIND:
      {
	gbind *bind = as_a <gbind *> (stmt);
	stmt = gimple_seq_last_nondebug_stmt (gimple_bind_body (bind));
	return last_stmt_in_scope (stmt);
      }

    case GIMPLE_TRY:
      {
	gtry *try_stmt = as_a <gtry *> (stmt);
	stmt = gimple_seq_last_nondebug_stmt (gimple_try_eval (try_stmt));
	gimple *last_eval = last_stmt_in_scope (stmt);
	if (gimple_stmt_may_fallthru (last_eval)
	    && (last_eval == NULL
		|| !gimple_call_internal_p (last_eval, IFN_FALLTHROUGH))
	    && gimple_try_kind (try_stmt) == GIMPLE_TRY_FINALLY)
	  {
	    stmt = gimple_seq_last_nondebug_stmt (gimple_try_cleanup (try_stmt));
	    return last_stmt_in_scope (stmt);
	  }
	else
	  return last_eval;
      }

    case GIMPLE_DEBUG:
      gcc_unreachable ();

    default:
      return stmt;
    }
}

/* Collect labels that may fall through into LABELS and return the statement
   preceding another case label, or a user-defined label.  Store a location
   useful to give warnings at *PREVLOC (usually the location of the returned
   statement or of its surrounding scope).  */

static gimple *
collect_fallthrough_labels (gimple_stmt_iterator *gsi_p,
			    auto_vec <struct label_entry> *labels,
			    location_t *prevloc)
{
  gimple *prev = NULL;

  *prevloc = UNKNOWN_LOCATION;
  do
    {
      if (gimple_code (gsi_stmt (*gsi_p)) == GIMPLE_BIND)
	{
	  /* Recognize the special GIMPLE_BIND added by gimplify_switch_expr,
	     which starts on a GIMPLE_SWITCH and ends with a break label.
	     Handle that as a single statement that can fall through.  */
	  gbind *bind = as_a <gbind *> (gsi_stmt (*gsi_p));
	  gimple *first = gimple_seq_first_stmt (gimple_bind_body (bind));
	  gimple *last = gimple_seq_last_stmt (gimple_bind_body (bind));
	  if (last
	      && gimple_code (first) == GIMPLE_SWITCH
	      && gimple_code (last) == GIMPLE_LABEL)
	    {
	      tree label = gimple_label_label (as_a <glabel *> (last));
	      if (SWITCH_BREAK_LABEL_P (label))
		{
		  prev = bind;
		  gsi_next (gsi_p);
		  continue;
		}
	    }
	}
      if (gimple_code (gsi_stmt (*gsi_p)) == GIMPLE_BIND
	  || gimple_code (gsi_stmt (*gsi_p)) == GIMPLE_TRY)
	{
	  /* Nested scope.  Only look at the last statement of
	     the innermost scope.  */
	  location_t bind_loc = gimple_location (gsi_stmt (*gsi_p));
	  gimple *last = last_stmt_in_scope (gsi_stmt (*gsi_p));
	  if (last)
	    {
	      prev = last;
	      /* It might be a label without a location.  Use the
		 location of the scope then.  */
	      if (!gimple_has_location (prev))
		*prevloc = bind_loc;
	    }
	  gsi_next (gsi_p);
	  continue;
	}

      /* Ifs are tricky.  */
      if (gimple_code (gsi_stmt (*gsi_p)) == GIMPLE_COND)
	{
	  gcond *cond_stmt = as_a <gcond *> (gsi_stmt (*gsi_p));
	  tree false_lab = gimple_cond_false_label (cond_stmt);
	  location_t if_loc = gimple_location (cond_stmt);

	  /* If we have e.g.
	       if (i > 1) goto <D.2259>; else goto D;
	     we can't do much with the else-branch.  */
	  if (!DECL_ARTIFICIAL (false_lab))
	    break;

	  /* Go on until the false label, then one step back.  */
	  for (; !gsi_end_p (*gsi_p); gsi_next (gsi_p))
	    {
	      gimple *stmt = gsi_stmt (*gsi_p);
	      if (gimple_code (stmt) == GIMPLE_LABEL
		  && gimple_label_label (as_a <glabel *> (stmt)) == false_lab)
		break;
	    }

	  /* Not found?  Oops.  */
	  if (gsi_end_p (*gsi_p))
	    break;

	  /* A dead label can't fall through.  */
	  if (!UNUSED_LABEL_P (false_lab))
	    {
	      struct label_entry l = { false_lab, if_loc };
	      labels->safe_push (l);
	    }

	  /* Go to the last statement of the then branch.  */
	  gsi_prev (gsi_p);

	  /* if (i != 0) goto <D.1759>; else goto <D.1760>;
	     <D.1759>:
	     <stmt>;
	     goto <D.1761>;
	     <D.1760>:
	   */
	  if (gimple_code (gsi_stmt (*gsi_p)) == GIMPLE_GOTO
	      && !gimple_has_location (gsi_stmt (*gsi_p)))
	    {
	      /* Look at the statement before, it might be
		 attribute fallthrough, in which case don't warn.  */
	      gsi_prev (gsi_p);
	      bool fallthru_before_dest
		= gimple_call_internal_p (gsi_stmt (*gsi_p), IFN_FALLTHROUGH);
	      gsi_next (gsi_p);
	      tree goto_dest = gimple_goto_dest (gsi_stmt (*gsi_p));
	      if (!fallthru_before_dest)
		{
		  struct label_entry l = { goto_dest, if_loc };
		  labels->safe_push (l);
		}
	    }
	  /* This case is about
	      if (1 != 0) goto <D.2022>; else goto <D.2023>;
	      <D.2022>:
	      n = n + 1; // #1
	      <D.2023>:  // #2
	      <D.1988>:  // #3
	     where #2 is UNUSED_LABEL_P and we want to warn about #1 falling
	     through to #3.  So set PREV to #1.  */
	  else if (UNUSED_LABEL_P (false_lab))
	    prev = gsi_stmt (*gsi_p);

	  /* And move back.  */
	  gsi_next (gsi_p);
	}

      /* Remember the last statement.  Skip labels that are of no interest
	 to us.  */
      if (gimple_code (gsi_stmt (*gsi_p)) == GIMPLE_LABEL)
	{
	  tree label = gimple_label_label (as_a <glabel *> (gsi_stmt (*gsi_p)));
	  if (find_label_entry (labels, label))
	    prev = gsi_stmt (*gsi_p);
	}
      else if (gimple_call_internal_p (gsi_stmt (*gsi_p), IFN_ASAN_MARK))
	;
      else if (gimple_code (gsi_stmt (*gsi_p)) == GIMPLE_PREDICT)
	;
      else if (!is_gimple_debug (gsi_stmt (*gsi_p)))
	prev = gsi_stmt (*gsi_p);
      gsi_next (gsi_p);
    }
  while (!gsi_end_p (*gsi_p)
	 /* Stop if we find a case or a user-defined label.  */
	 && (gimple_code (gsi_stmt (*gsi_p)) != GIMPLE_LABEL
	     || !gimple_has_location (gsi_stmt (*gsi_p))));

  if (prev && gimple_has_location (prev))
    *prevloc = gimple_location (prev);
  return prev;
}

/* Return true if the switch fallthough warning should occur.  LABEL is
   the label statement that we're falling through to.  */

static bool
should_warn_for_implicit_fallthrough (gimple_stmt_iterator *gsi_p, tree label)
{
  gimple_stmt_iterator gsi = *gsi_p;

  /* Don't warn if the label is marked with a "falls through" comment.  */
  if (FALLTHROUGH_LABEL_P (label))
    return false;

  /* Don't warn for non-case labels followed by a statement:
       case 0:
	 foo ();
       label:
	 bar ();
     as these are likely intentional.  */
  if (!case_label_p (&gimplify_ctxp->case_labels, label))
    {
      tree l;
      while (!gsi_end_p (gsi)
	     && gimple_code (gsi_stmt (gsi)) == GIMPLE_LABEL
	     && (l = gimple_label_label (as_a <glabel *> (gsi_stmt (gsi))))
	     && !case_label_p (&gimplify_ctxp->case_labels, l))
	gsi_next_nondebug (&gsi);
      if (gsi_end_p (gsi) || gimple_code (gsi_stmt (gsi)) != GIMPLE_LABEL)
	return false;
    }

  /* Don't warn for terminated branches, i.e. when the subsequent case labels
     immediately breaks.  */
  gsi = *gsi_p;

  /* Skip all immediately following labels.  */
  while (!gsi_end_p (gsi)
	 && (gimple_code (gsi_stmt (gsi)) == GIMPLE_LABEL
	     || gimple_code (gsi_stmt (gsi)) == GIMPLE_PREDICT))
    gsi_next_nondebug (&gsi);

  /* { ... something; default:; } */
  if (gsi_end_p (gsi)
      /* { ... something; default: break; } or
	 { ... something; default: goto L; } */
      || gimple_code (gsi_stmt (gsi)) == GIMPLE_GOTO
      /* { ... something; default: return; } */
      || gimple_code (gsi_stmt (gsi)) == GIMPLE_RETURN)
    return false;

  return true;
}

/* Callback for walk_gimple_seq.  */

static tree
warn_implicit_fallthrough_r (gimple_stmt_iterator *gsi_p, bool *handled_ops_p,
			     struct walk_stmt_info *)
{
  gimple *stmt = gsi_stmt (*gsi_p);

  *handled_ops_p = true;
  switch (gimple_code (stmt))
    {
    case GIMPLE_TRY:
    case GIMPLE_BIND:
    case GIMPLE_CATCH:
    case GIMPLE_EH_FILTER:
    case GIMPLE_TRANSACTION:
      /* Walk the sub-statements.  */
      *handled_ops_p = false;
      break;

    /* Find a sequence of form:

       GIMPLE_LABEL
       [...]
       <may fallthru stmt>
       GIMPLE_LABEL

       and possibly warn.  */
    case GIMPLE_LABEL:
      {
	/* Found a label.  Skip all immediately following labels.  */
	while (!gsi_end_p (*gsi_p)
	       && gimple_code (gsi_stmt (*gsi_p)) == GIMPLE_LABEL)
	  gsi_next_nondebug (gsi_p);

	/* There might be no more statements.  */
	if (gsi_end_p (*gsi_p))
	  return integer_zero_node;

	/* Vector of labels that fall through.  */
	auto_vec <struct label_entry> labels;
	location_t prevloc;
	gimple *prev = collect_fallthrough_labels (gsi_p, &labels, &prevloc);

	/* There might be no more statements.  */
	if (gsi_end_p (*gsi_p))
	  return integer_zero_node;

	gimple *next = gsi_stmt (*gsi_p);
	tree label;
	/* If what follows is a label, then we may have a fallthrough.  */
	if (gimple_code (next) == GIMPLE_LABEL
	    && gimple_has_location (next)
	    && (label = gimple_label_label (as_a <glabel *> (next)))
	    && prev != NULL)
	  {
	    struct label_entry *l;
	    bool warned_p = false;
	    auto_diagnostic_group d;
	    if (!should_warn_for_implicit_fallthrough (gsi_p, label))
	      /* Quiet.  */;
	    else if (gimple_code (prev) == GIMPLE_LABEL
		     && (label = gimple_label_label (as_a <glabel *> (prev)))
		     && (l = find_label_entry (&labels, label)))
	      warned_p = warning_at (l->loc, OPT_Wimplicit_fallthrough_,
				     "this statement may fall through");
	    else if (!gimple_call_internal_p (prev, IFN_FALLTHROUGH)
		     /* Try to be clever and don't warn when the statement
			can't actually fall through.  */
		     && gimple_stmt_may_fallthru (prev)
		     && prevloc != UNKNOWN_LOCATION)
	      warned_p = warning_at (prevloc,
				     OPT_Wimplicit_fallthrough_,
				     "this statement may fall through");
	    if (warned_p)
	      inform (gimple_location (next), "here");

	    /* Mark this label as processed so as to prevent multiple
	       warnings in nested switches.  */
	    FALLTHROUGH_LABEL_P (label) = true;

	    /* So that next warn_implicit_fallthrough_r will start looking for
	       a new sequence starting with this label.  */
	    gsi_prev (gsi_p);
	  }
      }
      break;
   default:
      break;
    }
  return NULL_TREE;
}

/* Warn when a switch case falls through.  */

static void
maybe_warn_implicit_fallthrough (gimple_seq seq)
{
  if (!warn_implicit_fallthrough)
    return;

  /* This warning is meant for C/C++/ObjC/ObjC++ only.  */
  if (!(lang_GNU_C ()
	|| lang_GNU_CXX ()
	|| lang_GNU_OBJC ()))
    return;

  struct walk_stmt_info wi;
  memset (&wi, 0, sizeof (wi));
  walk_gimple_seq (seq, warn_implicit_fallthrough_r, NULL, &wi);
}

/* Callback for walk_gimple_seq.  */

static tree
expand_FALLTHROUGH_r (gimple_stmt_iterator *gsi_p, bool *handled_ops_p,
		      struct walk_stmt_info *wi)
{
  gimple *stmt = gsi_stmt (*gsi_p);

  *handled_ops_p = true;
  switch (gimple_code (stmt))
    {
    case GIMPLE_TRY:
    case GIMPLE_BIND:
    case GIMPLE_CATCH:
    case GIMPLE_EH_FILTER:
    case GIMPLE_TRANSACTION:
      /* Walk the sub-statements.  */
      *handled_ops_p = false;
      break;
    case GIMPLE_CALL:
      if (gimple_call_internal_p (stmt, IFN_FALLTHROUGH))
	{
	  gsi_remove (gsi_p, true);
	  if (gsi_end_p (*gsi_p))
	    {
	      *static_cast<location_t *>(wi->info) = gimple_location (stmt);
	      return integer_zero_node;
	    }

	  bool found = false;
	  location_t loc = gimple_location (stmt);

	  gimple_stmt_iterator gsi2 = *gsi_p;
	  stmt = gsi_stmt (gsi2);
	  if (gimple_code (stmt) == GIMPLE_GOTO && !gimple_has_location (stmt))
	    {
	      /* Go on until the artificial label.  */
	      tree goto_dest = gimple_goto_dest (stmt);
	      for (; !gsi_end_p (gsi2); gsi_next (&gsi2))
		{
		  if (gimple_code (gsi_stmt (gsi2)) == GIMPLE_LABEL
		      && gimple_label_label (as_a <glabel *> (gsi_stmt (gsi2)))
			   == goto_dest)
		    break;
		}

	      /* Not found?  Stop.  */
	      if (gsi_end_p (gsi2))
		break;

	      /* Look one past it.  */
	      gsi_next (&gsi2);
	    }

	  /* We're looking for a case label or default label here.  */
	  while (!gsi_end_p (gsi2))
	    {
	      stmt = gsi_stmt (gsi2);
	      if (gimple_code (stmt) == GIMPLE_LABEL)
		{
		  tree label = gimple_label_label (as_a <glabel *> (stmt));
		  if (gimple_has_location (stmt) && DECL_ARTIFICIAL (label))
		    {
		      found = true;
		      break;
		    }
		}
	      else if (gimple_call_internal_p (stmt, IFN_ASAN_MARK))
		;
	      else if (!is_gimple_debug (stmt))
		/* Anything else is not expected.  */
		break;
	      gsi_next (&gsi2);
	    }
	  if (!found)
	    pedwarn (loc, 0, "attribute %<fallthrough%> not preceding "
		     "a case label or default label");
	}
      break;
    default:
      break;
    }
  return NULL_TREE;
}

/* Expand all FALLTHROUGH () calls in SEQ.  */

static void
expand_FALLTHROUGH (gimple_seq *seq_p)
{
  struct walk_stmt_info wi;
  location_t loc;
  memset (&wi, 0, sizeof (wi));
  wi.info = (void *) &loc;
  walk_gimple_seq_mod (seq_p, expand_FALLTHROUGH_r, NULL, &wi);
  if (wi.callback_result == integer_zero_node)
    /* We've found [[fallthrough]]; at the end of a switch, which the C++
       standard says is ill-formed; see [dcl.attr.fallthrough].  */
    pedwarn (loc, 0, "attribute %<fallthrough%> not preceding "
	     "a case label or default label");
}


/* Gimplify a SWITCH_EXPR, and collect the vector of labels it can
   branch to.  */

static enum gimplify_status
gimplify_switch_expr (tree *expr_p, gimple_seq *pre_p)
{
  tree switch_expr = *expr_p;
  gimple_seq switch_body_seq = NULL;
  enum gimplify_status ret;
  tree index_type = TREE_TYPE (switch_expr);
  if (index_type == NULL_TREE)
    index_type = TREE_TYPE (SWITCH_COND (switch_expr));

  ret = gimplify_expr (&SWITCH_COND (switch_expr), pre_p, NULL, is_gimple_val,
                       fb_rvalue);
  if (ret == GS_ERROR || ret == GS_UNHANDLED)
    return ret;

  if (SWITCH_BODY (switch_expr))
    {
      vec<tree> labels;
      vec<tree> saved_labels;
      hash_set<tree> *saved_live_switch_vars = NULL;
      tree default_case = NULL_TREE;
      gswitch *switch_stmt;

      /* Save old labels, get new ones from body, then restore the old
         labels.  Save all the things from the switch body to append after.  */
      saved_labels = gimplify_ctxp->case_labels;
      gimplify_ctxp->case_labels.create (8);

      /* Do not create live_switch_vars if SWITCH_BODY is not a BIND_EXPR.  */
      saved_live_switch_vars = gimplify_ctxp->live_switch_vars;
      tree_code body_type = TREE_CODE (SWITCH_BODY (switch_expr));
      if (body_type == BIND_EXPR || body_type == STATEMENT_LIST)
	gimplify_ctxp->live_switch_vars = new hash_set<tree> (4);
      else
	gimplify_ctxp->live_switch_vars = NULL;

      bool old_in_switch_expr = gimplify_ctxp->in_switch_expr;
      gimplify_ctxp->in_switch_expr = true;

      gimplify_stmt (&SWITCH_BODY (switch_expr), &switch_body_seq);

      gimplify_ctxp->in_switch_expr = old_in_switch_expr;
      maybe_warn_switch_unreachable_and_auto_init (switch_body_seq);
      maybe_warn_implicit_fallthrough (switch_body_seq);
      /* Only do this for the outermost GIMPLE_SWITCH.  */
      if (!gimplify_ctxp->in_switch_expr)
	expand_FALLTHROUGH (&switch_body_seq);

      labels = gimplify_ctxp->case_labels;
      gimplify_ctxp->case_labels = saved_labels;

      if (gimplify_ctxp->live_switch_vars)
	{
	  gcc_assert (gimplify_ctxp->live_switch_vars->is_empty ());
	  delete gimplify_ctxp->live_switch_vars;
	}
      gimplify_ctxp->live_switch_vars = saved_live_switch_vars;

      preprocess_case_label_vec_for_gimple (labels, index_type,
					    &default_case);

      bool add_bind = false;
      if (!default_case)
	{
	  glabel *new_default;

	  default_case
	    = build_case_label (NULL_TREE, NULL_TREE,
				create_artificial_label (UNKNOWN_LOCATION));
	  if (old_in_switch_expr)
	    {
	      SWITCH_BREAK_LABEL_P (CASE_LABEL (default_case)) = 1;
	      add_bind = true;
	    }
	  new_default = gimple_build_label (CASE_LABEL (default_case));
	  gimplify_seq_add_stmt (&switch_body_seq, new_default);
	}
      else if (old_in_switch_expr)
	{
	  gimple *last = gimple_seq_last_stmt (switch_body_seq);
	  if (last && gimple_code (last) == GIMPLE_LABEL)
	    {
	      tree label = gimple_label_label (as_a <glabel *> (last));
	      if (SWITCH_BREAK_LABEL_P (label))
		add_bind = true;
	    }
	}

      switch_stmt = gimple_build_switch (SWITCH_COND (switch_expr),
					 default_case, labels);
      /* For the benefit of -Wimplicit-fallthrough, if switch_body_seq
	 ends with a GIMPLE_LABEL holding SWITCH_BREAK_LABEL_P LABEL_DECL,
	 wrap the GIMPLE_SWITCH up to that GIMPLE_LABEL into a GIMPLE_BIND,
	 so that we can easily find the start and end of the switch
	 statement.  */
      if (add_bind)
	{
	  gimple_seq bind_body = NULL;
	  gimplify_seq_add_stmt (&bind_body, switch_stmt);
	  gimple_seq_add_seq (&bind_body, switch_body_seq);
	  gbind *bind = gimple_build_bind (NULL_TREE, bind_body, NULL_TREE);
	  gimple_set_location (bind, EXPR_LOCATION (switch_expr));
	  gimplify_seq_add_stmt (pre_p, bind);
	}
      else
	{
	  gimplify_seq_add_stmt (pre_p, switch_stmt);
	  gimplify_seq_add_seq (pre_p, switch_body_seq);
	}
      labels.release ();
    }
  else
    gcc_unreachable ();

  return GS_ALL_DONE;
}

/* Gimplify the LABEL_EXPR pointed to by EXPR_P.  */

static enum gimplify_status
gimplify_label_expr (tree *expr_p, gimple_seq *pre_p)
{
  gcc_assert (decl_function_context (LABEL_EXPR_LABEL (*expr_p))
	      == current_function_decl);

  tree label = LABEL_EXPR_LABEL (*expr_p);
  glabel *label_stmt = gimple_build_label (label);
  gimple_set_location (label_stmt, EXPR_LOCATION (*expr_p));
  gimplify_seq_add_stmt (pre_p, label_stmt);

  if (lookup_attribute ("cold", DECL_ATTRIBUTES (label)))
    gimple_seq_add_stmt (pre_p, gimple_build_predict (PRED_COLD_LABEL,
						      NOT_TAKEN));
  else if (lookup_attribute ("hot", DECL_ATTRIBUTES (label)))
    gimple_seq_add_stmt (pre_p, gimple_build_predict (PRED_HOT_LABEL,
						      TAKEN));

  return GS_ALL_DONE;
}

/* Gimplify the CASE_LABEL_EXPR pointed to by EXPR_P.  */

static enum gimplify_status
gimplify_case_label_expr (tree *expr_p, gimple_seq *pre_p)
{
  struct gimplify_ctx *ctxp;
  glabel *label_stmt;

  /* Invalid programs can play Duff's Device type games with, for example,
     #pragma omp parallel.  At least in the C front end, we don't
     detect such invalid branches until after gimplification, in the
     diagnose_omp_blocks pass.  */
  for (ctxp = gimplify_ctxp; ; ctxp = ctxp->prev_context)
    if (ctxp->case_labels.exists ())
      break;

  tree label = CASE_LABEL (*expr_p);
  label_stmt = gimple_build_label (label);
  gimple_set_location (label_stmt, EXPR_LOCATION (*expr_p));
  ctxp->case_labels.safe_push (*expr_p);
  gimplify_seq_add_stmt (pre_p, label_stmt);

  if (lookup_attribute ("cold", DECL_ATTRIBUTES (label)))
    gimple_seq_add_stmt (pre_p, gimple_build_predict (PRED_COLD_LABEL,
						      NOT_TAKEN));
  else if (lookup_attribute ("hot", DECL_ATTRIBUTES (label)))
    gimple_seq_add_stmt (pre_p, gimple_build_predict (PRED_HOT_LABEL,
						      TAKEN));

  return GS_ALL_DONE;
}

/* Build a GOTO to the LABEL_DECL pointed to by LABEL_P, building it first
   if necessary.  */

tree
build_and_jump (tree *label_p)
{
  if (label_p == NULL)
    /* If there's nowhere to jump, just fall through.  */
    return NULL_TREE;

  if (*label_p == NULL_TREE)
    {
      tree label = create_artificial_label (UNKNOWN_LOCATION);
      *label_p = label;
    }

  return build1 (GOTO_EXPR, void_type_node, *label_p);
}

/* Gimplify an EXIT_EXPR by converting to a GOTO_EXPR inside a COND_EXPR.
   This also involves building a label to jump to and communicating it to
   gimplify_loop_expr through gimplify_ctxp->exit_label.  */

static enum gimplify_status
gimplify_exit_expr (tree *expr_p)
{
  tree cond = TREE_OPERAND (*expr_p, 0);
  tree expr;

  expr = build_and_jump (&gimplify_ctxp->exit_label);
  expr = build3 (COND_EXPR, void_type_node, cond, expr, NULL_TREE);
  *expr_p = expr;

  return GS_OK;
}

/* *EXPR_P is a COMPONENT_REF being used as an rvalue.  If its type is
   different from its canonical type, wrap the whole thing inside a
   NOP_EXPR and force the type of the COMPONENT_REF to be the canonical
   type.

   The canonical type of a COMPONENT_REF is the type of the field being
   referenced--unless the field is a bit-field which can be read directly
   in a smaller mode, in which case the canonical type is the
   sign-appropriate type corresponding to that mode.  */

static void
canonicalize_component_ref (tree *expr_p)
{
  tree expr = *expr_p;
  tree type;

  gcc_assert (TREE_CODE (expr) == COMPONENT_REF);

  if (INTEGRAL_TYPE_P (TREE_TYPE (expr)))
    type = TREE_TYPE (get_unwidened (expr, NULL_TREE));
  else
    type = TREE_TYPE (TREE_OPERAND (expr, 1));

  /* One could argue that all the stuff below is not necessary for
     the non-bitfield case and declare it a FE error if type
     adjustment would be needed.  */
  if (TREE_TYPE (expr) != type)
    {
#ifdef ENABLE_TYPES_CHECKING
      tree old_type = TREE_TYPE (expr);
#endif
      int type_quals;

      /* We need to preserve qualifiers and propagate them from
	 operand 0.  */
      type_quals = TYPE_QUALS (type)
	| TYPE_QUALS (TREE_TYPE (TREE_OPERAND (expr, 0)));
      if (TYPE_QUALS (type) != type_quals)
	type = build_qualified_type (TYPE_MAIN_VARIANT (type), type_quals);

      /* Set the type of the COMPONENT_REF to the underlying type.  */
      TREE_TYPE (expr) = type;

#ifdef ENABLE_TYPES_CHECKING
      /* It is now a FE error, if the conversion from the canonical
	 type to the original expression type is not useless.  */
      gcc_assert (useless_type_conversion_p (old_type, type));
#endif
    }
}

/* If a NOP conversion is changing a pointer to array of foo to a pointer
   to foo, embed that change in the ADDR_EXPR by converting
      T array[U];
      (T *)&array
   ==>
      &array[L]
   where L is the lower bound.  For simplicity, only do this for constant
   lower bound.
   The constraint is that the type of &array[L] is trivially convertible
   to T *.  */

static void
canonicalize_addr_expr (tree *expr_p)
{
  tree expr = *expr_p;
  tree addr_expr = TREE_OPERAND (expr, 0);
  tree datype, ddatype, pddatype;

  /* We simplify only conversions from an ADDR_EXPR to a pointer type.  */
  if (!POINTER_TYPE_P (TREE_TYPE (expr))
      || TREE_CODE (addr_expr) != ADDR_EXPR)
    return;

  /* The addr_expr type should be a pointer to an array.  */
  datype = TREE_TYPE (TREE_TYPE (addr_expr));
  if (TREE_CODE (datype) != ARRAY_TYPE)
    return;

  /* The pointer to element type shall be trivially convertible to
     the expression pointer type.  */
  ddatype = TREE_TYPE (datype);
  pddatype = build_pointer_type (ddatype);
  if (!useless_type_conversion_p (TYPE_MAIN_VARIANT (TREE_TYPE (expr)),
				  pddatype))
    return;

  /* The lower bound and element sizes must be constant.  */
  if (!TYPE_SIZE_UNIT (ddatype)
      || TREE_CODE (TYPE_SIZE_UNIT (ddatype)) != INTEGER_CST
      || !TYPE_DOMAIN (datype) || !TYPE_MIN_VALUE (TYPE_DOMAIN (datype))
      || TREE_CODE (TYPE_MIN_VALUE (TYPE_DOMAIN (datype))) != INTEGER_CST)
    return;

  /* All checks succeeded.  Build a new node to merge the cast.  */
  *expr_p = build4 (ARRAY_REF, ddatype, TREE_OPERAND (addr_expr, 0),
		    TYPE_MIN_VALUE (TYPE_DOMAIN (datype)),
		    NULL_TREE, NULL_TREE);
  *expr_p = build1 (ADDR_EXPR, pddatype, *expr_p);

  /* We can have stripped a required restrict qualifier above.  */
  if (!useless_type_conversion_p (TREE_TYPE (expr), TREE_TYPE (*expr_p)))
    *expr_p = fold_convert (TREE_TYPE (expr), *expr_p);
}

/* *EXPR_P is a NOP_EXPR or CONVERT_EXPR.  Remove it and/or other conversions
   underneath as appropriate.  */

static enum gimplify_status
gimplify_conversion (tree *expr_p)
{
  location_t loc = EXPR_LOCATION (*expr_p);
  gcc_assert (CONVERT_EXPR_P (*expr_p));

  /* Then strip away all but the outermost conversion.  */
  STRIP_SIGN_NOPS (TREE_OPERAND (*expr_p, 0));