https://gcc.gnu.org/g:db73411a72cf2052dddcf9fa0523588599a73537
commit r14-11788-gdb73411a72cf2052dddcf9fa0523588599a73537
Author: Jakub Jelinek <ja...@redhat.com>
Date: Thu Feb 13 10:21:29 2025 +0100
c++: Fix up regressions caused by for/while loops with declarations
[PR118822]
The recent PR86769 r15-7426 changes regressed the following two testcases,
the first one is more important as it is derived from real-world code.
The first problem is that the chosen
prep = do_pushlevel (sk_block);
// emit something
body = push_stmt_list ();
// emit further stuff
body = pop_stmt_list (body);
prep = do_poplevel (prep);
way of constructing the {FOR,WHILE}_COND_PREP and {FOR,WHILE}_BODY
isn't reliable. If during parsing a label is seen in the body and then
some decl with destructors, sk_cleanup transparent scope is added, but
the correspondiong result from push_stmt_list is saved in
*current_binding_level and pop_stmt_list then pops even that statement list
but only do_poplevel actually attempts to pop the sk_cleanup scope and so we
ICE.
The reason for not doing do_pushlevel (sk_block); do_pushlevel (sk_block);
is that variables should be in the same scope (otherwise various e.g.
redeclaration*.C tests FAIL) and doing do_pushlevel (sk_block); do_pushlevel
(sk_cleanup); wouldn't work either as do_poplevel would silently unwind even
the cleanup one.
So, the following patch changes the earlier approach. Nothing is removed
from the {FOR,WHILE}_COND_PREP subtrees while doing adjust_loop_decl_cond,
push_stmt_list isn't called either; all it does is remember as an integer
the number of cleanups (CLEANUP_STMT at the end of the STATEMENT_LISTs)
from querying stmt_list_stack and finding the initial *body_p in there
(that integer is stored into {FOR,WHILE}_COND_CLEANUP), and temporarily
{FOR,WHILE}_BODY is set to the last statement (if any) in the innermost
STATEMENT_LIST at the adjust_loop_decl_cond time; then at
finish_{for,while}_stmt a new finish_loop_cond_prep routine takes care of
do_poplevel for the scope (which is in {FOR,WHILE}_COND_PREP) and finds
given {FOR,WHILE}_COND_CLEANUP number and {FOR,WHILE}_BODY tree the right
spot where body statements start and moves that into {FOR,WHILE}_BODY.
Finally genericize_c_loop then inserts the cond, body, continue label, expr
into the right subtree of {FOR,WHILE}_COND_PREP.
The constexpr evaluation unfortunately had to be changed as well, because
we don't want to evaluate everything in BIND_EXPR_BODY (*_COND_PREP ())
right away, we want to evaluate it with the exception of the CLEANUP_STMT
cleanups at the end (given {FOR,WHILE}_COND_CLEANUP levels), and defer
the evaluation of the cleanups until after cond, body, expr are evaluated.
2025-02-13 Jakub Jelinek <ja...@redhat.com>
PR c++/118822
gcc/
* tree-iterator.h (tsi_split_stmt_list): Declare.
* tree-iterator.cc (tsi_split_stmt_list): New function.
gcc/c-family/
* c-common.h (WHILE_COND_CLEANUP): Change description in comment.
(FOR_COND_CLEANUP): Likewise.
* c-gimplify.cc (genericize_c_loop): Adjust for COND_CLEANUP
being CLEANUP_STMT/TRY_FINALLY_EXPR trailing nesting depth
instead of actual cleanup.
gcc/cp/
* semantics.cc (adjust_loop_decl_cond): Allow multiple trailing
CLEANUP_STMT levels in *BODY_P. Set *CLEANUP_P to the number
of levels rather than one particular cleanup, keep the cleanups
in *PREP_P. Set *BODY_P to the last stmt in the cur_stmt_list
or NULL if *CLEANUP_P and the innermost cur_stmt_list is empty.
(finish_loop_cond_prep): New function.
(finish_while_stmt, finish_for_stmt): Use it. Don't call
set_one_cleanup_loc.
* constexpr.cc (cxx_eval_loop_expr): Adjust handling of
{FOR,WHILE}_COND_{PREP,CLEANUP}.
gcc/testsuite/
* g++.dg/expr/for9.C: New test.
(cherry picked from commit 26baa2c09b39abf037afad349a318dc5734eae25)
Diff:
---
gcc/c-family/c-common.h | 6 +-
gcc/c-family/c-gimplify.cc | 41 +++++--------
gcc/cp/constexpr.cc | 97 ++++++++++++++++++++++++++---
gcc/cp/semantics.cc | 128 ++++++++++++++++++++++++++++-----------
gcc/testsuite/g++.dg/expr/for9.C | 25 ++++++++
gcc/tree-iterator.cc | 22 +++++++
gcc/tree-iterator.h | 1 +
7 files changed, 251 insertions(+), 69 deletions(-)
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index 41f7ca3ef012..8d8bead50306 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -1492,7 +1492,8 @@ extern tree build_userdef_literal (tree suffix_id, tree
value,
/* WHILE_STMT accessors. These give access to the condition of the
while statement and the body of the while statement, and
- condition preparation statements and its cleanup, respectively. */
+ condition preparation statements and number of its nested cleanups,
+ respectively. */
#define WHILE_COND(NODE) TREE_OPERAND (WHILE_STMT_CHECK (NODE), 0)
#define WHILE_BODY(NODE) TREE_OPERAND (WHILE_STMT_CHECK (NODE), 1)
#define WHILE_COND_PREP(NODE) TREE_OPERAND (WHILE_STMT_CHECK (NODE), 2)
@@ -1505,7 +1506,8 @@ extern tree build_userdef_literal (tree suffix_id, tree
value,
/* FOR_STMT accessors. These give access to the init statement,
condition, update expression, and body of the for statement,
- and condition preparation statements and its cleanup, respectively. */
+ and condition preparation statements and number of its nested cleanups,
+ respectively. */
#define FOR_INIT_STMT(NODE) TREE_OPERAND (FOR_STMT_CHECK (NODE), 0)
#define FOR_COND(NODE) TREE_OPERAND (FOR_STMT_CHECK (NODE), 1)
#define FOR_EXPR(NODE) TREE_OPERAND (FOR_STMT_CHECK (NODE), 2)
diff --git a/gcc/c-family/c-gimplify.cc b/gcc/c-family/c-gimplify.cc
index 3fb2aa123cae..3f8ba37b863b 100644
--- a/gcc/c-family/c-gimplify.cc
+++ b/gcc/c-family/c-gimplify.cc
@@ -229,8 +229,10 @@ expr_loc_or_loc (const_tree expr, location_t or_loc)
for C++ for/while loops with variable declaration as condition. COND_PREP
is a BIND_EXPR with the declaration and initialization of the condition
variable, into which COND, BODY, continue label if needed and INCR if
- non-NULL should be appended, and COND_CLEANUP are statements which should
- be evaluated after that or if anything in COND, BODY or INCR throws. */
+ non-NULL should be appended, and COND_CLEANUP is number of nested
+ CLEANUP_STMT -> TRY_FINALLY_EXPR statements at the end. If non-NULL,
+ COND, BODY, continue label if needed and INCR if non-NULL should be
+ appended to the body of the COND_CLEANUP's nested TRY_FINALLY_EXPR. */
static void
genericize_c_loop (tree *stmt_p, location_t start_locus, tree cond, tree body,
@@ -249,7 +251,6 @@ genericize_c_loop (tree *stmt_p, location_t start_locus,
tree cond, tree body,
walk_tree_1 (&cond_prep, func, data, NULL, lh);
walk_tree_1 (&cond, func, data, NULL, lh);
walk_tree_1 (&incr, func, data, NULL, lh);
- walk_tree_1 (&cond_cleanup, func, data, NULL, lh);
blab = begin_bc_block (bc_break, start_locus);
clab = begin_bc_block (bc_continue, start_locus);
@@ -275,36 +276,24 @@ genericize_c_loop (tree *stmt_p, location_t start_locus,
tree cond, tree body,
EXPR;
goto top;
- or
-
- try {
- if (COND); else break;
- BODY;
- cont:
- EXPR;
- } finally {
- COND_CLEANUP
- }
-
- appended into COND_PREP body. */
+ appended into COND_PREP body or body of some TRY_FINALLY_EXPRs
+ at the end of COND_PREP. */
gcc_assert (cond_is_first && TREE_CODE (cond_prep) == BIND_EXPR);
tree top = build1 (LABEL_EXPR, void_type_node,
create_artificial_label (start_locus));
exit = build1 (GOTO_EXPR, void_type_node, LABEL_EXPR_LABEL (top));
append_to_statement_list (top, &outer_stmt_list);
append_to_statement_list (cond_prep, &outer_stmt_list);
- stmt_list = BIND_EXPR_BODY (cond_prep);
- BIND_EXPR_BODY (cond_prep) = NULL_TREE;
stmt_list_p = &BIND_EXPR_BODY (cond_prep);
- if (cond_cleanup && TREE_SIDE_EFFECTS (cond_cleanup))
- {
- t = build2_loc (EXPR_LOCATION (cond_cleanup), TRY_FINALLY_EXPR,
- void_type_node, NULL_TREE, cond_cleanup);
- append_to_statement_list (t, &stmt_list);
- *stmt_list_p = stmt_list;
- stmt_list_p = &TREE_OPERAND (t, 0);
- stmt_list = NULL_TREE;
- }
+ if (cond_cleanup)
+ for (unsigned depth = tree_to_uhwi (cond_cleanup); depth; --depth)
+ {
+ t = tsi_stmt (tsi_last (*stmt_list_p));
+ gcc_assert (TREE_CODE (t) == TRY_FINALLY_EXPR);
+ stmt_list_p = &TREE_OPERAND (t, 0);
+ }
+ stmt_list = *stmt_list_p;
+ *stmt_list_p = NULL_TREE;
tree after_cond = create_artificial_label (cond_locus);
tree goto_after_cond = build1 (GOTO_EXPR, void_type_node, after_cond);
t = build1 (GOTO_EXPR, void_type_node, get_bc_label (bc_break));
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 67e76367b9eb..df5bdb96862e 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -7090,6 +7090,7 @@ cxx_eval_loop_expr (const constexpr_ctx *ctx, tree t,
tree body, cond = NULL_TREE, expr = NULL_TREE;
tree cond_prep = NULL_TREE, cond_cleanup = NULL_TREE;
+ unsigned cond_cleanup_depth = 0;
int count = 0;
switch (TREE_CODE (t))
{
@@ -7125,11 +7126,25 @@ cxx_eval_loop_expr (const constexpr_ctx *ctx, tree t,
}
if (cond_prep)
gcc_assert (TREE_CODE (cond_prep) == BIND_EXPR);
- auto cleanup_cond = [=] {
+ auto cleanup_cond = [&] {
/* Clean up the condition variable after each iteration. */
- if (cond_cleanup && !*non_constant_p)
- cxx_eval_constant_expression (ctx, cond_cleanup, vc_discard,
- non_constant_p, overflow_p);
+ if (cond_cleanup_depth && !*non_constant_p)
+ {
+ auto_vec<tree, 4> cleanups (cond_cleanup_depth);
+ tree s = BIND_EXPR_BODY (cond_prep);
+ unsigned i;
+ for (i = cond_cleanup_depth; i; --i)
+ {
+ tree_stmt_iterator iter = tsi_last (s);
+ s = tsi_stmt (iter);
+ cleanups.quick_push (CLEANUP_EXPR (s));
+ s = CLEANUP_BODY (s);
+ }
+ tree c;
+ FOR_EACH_VEC_ELT_REVERSE (cleanups, i, c)
+ cxx_eval_constant_expression (ctx, c, vc_discard, non_constant_p,
+ overflow_p);
+ }
if (cond_prep)
for (tree decl = BIND_EXPR_VARS (cond_prep);
decl; decl = DECL_CHAIN (decl))
@@ -7164,9 +7179,77 @@ cxx_eval_loop_expr (const constexpr_ctx *ctx, tree t,
for (tree decl = BIND_EXPR_VARS (cond_prep);
decl; decl = DECL_CHAIN (decl))
ctx->global->clear_value (decl);
- cxx_eval_constant_expression (ctx, BIND_EXPR_BODY (cond_prep),
- vc_discard, non_constant_p,
- overflow_p, jump_target);
+ if (cond_cleanup)
+ {
+ /* If COND_CLEANUP is non-NULL, we need to evaluate DEPTH
+ nested STATEMENT_LISTs from inside of BIND_EXPR_BODY,
+ but defer the evaluation of CLEANUP_EXPRs of CLEANUP_STMT
+ at the end of those STATEMENT_LISTs. */
+ cond_cleanup_depth = 0;
+ tree s = BIND_EXPR_BODY (cond_prep);
+ for (unsigned depth = tree_to_uhwi (cond_cleanup);
+ depth; --depth)
+ {
+ for (tree_stmt_iterator i = tsi_start (s);
+ !tsi_end_p (i); ++i)
+ {
+ tree stmt = *i;
+ if (TREE_CODE (stmt) == DEBUG_BEGIN_STMT)
+ continue;
+ if (tsi_one_before_end_p (i))
+ {
+ /* The last statement in the STATEMENT_LIST
+ has to be a CLEANUP_STMT (verified in
+ finish_loop_cond_prep). We want to
+ evaluate just its CLEANUP_BODY part but not
+ CLEANUP_EXPR part just yet. */
+ gcc_assert (TREE_CODE (stmt) == CLEANUP_STMT);
+ /* If the CLEANUP_STMT is not actually to be
+ evaluated, don't increment cond_cleanup_depth
+ so that we don't evaluate the CLEANUP_EXPR
+ for it later either. */
+ if (*jump_target)
+ {
+ depth = 1;
+ break;
+ }
+ ++cond_cleanup_depth;
+ /* If not in the innermost one, next iteration
+ will handle CLEANUP_BODY similarly. */
+ if (depth > 1)
+ {
+ s = CLEANUP_BODY (stmt);
+ break;
+ }
+ /* The innermost one can be evaluated normally. */
+ cxx_eval_constant_expression (ctx,
+ CLEANUP_BODY (stmt),
+ vc_discard,
+ non_constant_p,
+ overflow_p,
+ jump_target);
+ break;
+ }
+ /* And so should be evaluated statements which aren't
+ last in the STATEMENT_LIST. */
+ cxx_eval_constant_expression (ctx, stmt, vc_discard,
+ non_constant_p, overflow_p,
+ jump_target);
+ if (*non_constant_p
+ || returns (jump_target)
+ || breaks (jump_target)
+ || continues (jump_target))
+ {
+ depth = 1;
+ break;
+ }
+ }
+ }
+ }
+ else
+ cxx_eval_constant_expression (ctx, BIND_EXPR_BODY (cond_prep),
+ vc_discard, non_constant_p,
+ overflow_p, jump_target);
}
if (cond)
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index c5702a9926c0..31e7b26b4521 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -790,8 +790,8 @@ finish_cond (tree *cond_p, tree expr)
while (A x = 42) { }
for (; A x = 42;) { }
move the *BODY_P statements as a BIND_EXPR into {FOR,WHILE}_COND_PREP
- and if there is any CLEANUP_STMT at the end, remove that and
- put the cleanup into {FOR,WHILE}_COND_CLEANUP.
+ and if there are any CLEANUP_STMT at the end, remember their count in
+ {FOR,WHILE}_COND_CLEANUP.
genericize_c_loop will then handle it appropriately. In particular,
the {FOR,WHILE}_COND, {FOR,WHILE}_BODY, if used continue label and
FOR_EXPR will be appended into the {FOR,WHILE}_COND_PREP BIND_EXPR,
@@ -807,26 +807,88 @@ adjust_loop_decl_cond (tree *body_p, tree *prep_p, tree
*cleanup_p)
return;
gcc_assert (!processing_template_decl);
- if (*body_p != cur_stmt_list)
- {
- /* There can be either no cleanup at all, if the condition
- declaration doesn't have non-trivial destructor, or a single
- one if it does. In that case extract it into *CLEANUP_P. */
- gcc_assert (stmt_list_stack->length () > 1
- && (*stmt_list_stack)[stmt_list_stack->length ()
- - 2] == *body_p);
- tree_stmt_iterator last = tsi_last (*body_p);
- gcc_assert (tsi_one_before_end_p (last)
- && TREE_CODE (tsi_stmt (last)) == CLEANUP_STMT
- && CLEANUP_BODY (tsi_stmt (last)) == cur_stmt_list
- && tsi_end_p (tsi_last (cur_stmt_list))
- && !CLEANUP_EH_ONLY (tsi_stmt (last)));
- *cleanup_p = CLEANUP_EXPR (tsi_stmt (last));
- tsi_delink (&last);
+ *prep_p = *body_p;
+ if (*prep_p != cur_stmt_list)
+ {
+ /* There can be just one CLEANUP_STMT, or there could be multiple
+ nested CLEANUP_STMTs, e.g. for structured bindings used as
+ condition. */
+ gcc_assert (stmt_list_stack->length () > 1);
+ for (unsigned i = stmt_list_stack->length () - 2; ; --i)
+ {
+ tree t = (*stmt_list_stack)[i];
+ tree_stmt_iterator last = tsi_last (t);
+ gcc_assert (tsi_one_before_end_p (last)
+ && TREE_CODE (tsi_stmt (last)) == CLEANUP_STMT
+ && (CLEANUP_BODY (tsi_stmt (last))
+ == (*stmt_list_stack)[i + 1])
+ && !CLEANUP_EH_ONLY (tsi_stmt (last)));
+ if (t == *prep_p)
+ {
+ *cleanup_p = build_int_cst (long_unsigned_type_node,
+ stmt_list_stack->length () - 1 - i);
+ break;
+ }
+ gcc_assert (i >= 1);
+ }
}
current_binding_level->keep = true;
- *prep_p = *body_p;
- *body_p = push_stmt_list ();
+ tree_stmt_iterator iter = tsi_last (cur_stmt_list);
+ /* Temporarily store in {FOR,WHILE}_BODY the last statement of
+ the innnermost statement list or NULL if it has no statement.
+ This is used in finish_loop_cond_prep to find out the splitting
+ point and then {FOR,WHILE}_BODY will be changed to the actual
+ body. */
+ if (tsi_end_p (iter))
+ *body_p = NULL_TREE;
+ else
+ *body_p = tsi_stmt (iter);
+}
+
+/* Finalize {FOR,WHILE}_{BODY,COND_PREP} after the loop body.
+ The above function initialized *BODY_P to the last statement
+ in *PREP_P at that point.
+ Call do_poplevel on *PREP_P and move everything after that
+ former last statement into *BODY_P. genericize_c_loop
+ will later put those parts back together.
+ CLEANUP is {FOR,WHILE}_COND_CLEANUP. */
+
+static void
+finish_loop_cond_prep (tree *body_p, tree *prep_p, tree cleanup)
+{
+ *prep_p = do_poplevel (*prep_p);
+ gcc_assert (TREE_CODE (*prep_p) == BIND_EXPR);
+ if (BIND_EXPR_BODY (*prep_p) == *body_p)
+ {
+ gcc_assert (cleanup == NULL_TREE);
+ *body_p = build_empty_stmt (input_location);
+ return;
+ }
+ tree stmt_list = BIND_EXPR_BODY (*prep_p);
+ gcc_assert (TREE_CODE (stmt_list) == STATEMENT_LIST);
+ if (cleanup)
+ {
+ tree_stmt_iterator iter = tsi_last (stmt_list);
+ gcc_assert (TREE_CODE (tsi_stmt (iter)) == CLEANUP_STMT);
+ for (unsigned depth = tree_to_uhwi (cleanup); depth > 1; --depth)
+ {
+ gcc_assert (TREE_CODE (CLEANUP_BODY (tsi_stmt (iter)))
+ == STATEMENT_LIST);
+ iter = tsi_last (CLEANUP_BODY (tsi_stmt (iter)));
+ gcc_assert (TREE_CODE (tsi_stmt (iter)) == CLEANUP_STMT);
+ }
+ if (*body_p == NULL_TREE)
+ {
+ *body_p = CLEANUP_BODY (tsi_stmt (iter));
+ CLEANUP_BODY (tsi_stmt (iter)) = build_empty_stmt (input_location);
+ return;
+ }
+ stmt_list = CLEANUP_BODY (tsi_stmt (iter));
+ }
+ tree_stmt_iterator iter = tsi_start (stmt_list);
+ while (tsi_stmt (iter) != *body_p)
+ tsi_next (&iter);
+ *body_p = tsi_split_stmt_list (input_location, iter);
}
/* Finish a goto-statement. */
@@ -1341,14 +1403,13 @@ void
finish_while_stmt (tree while_stmt)
{
end_maybe_infinite_loop (boolean_true_node);
- WHILE_BODY (while_stmt)
- = (WHILE_COND_PREP (while_stmt)
- ? pop_stmt_list (WHILE_BODY (while_stmt))
- : do_poplevel (WHILE_BODY (while_stmt)));
- finish_loop_cond (&WHILE_COND (while_stmt), WHILE_BODY (while_stmt));
if (WHILE_COND_PREP (while_stmt))
- WHILE_COND_PREP (while_stmt) = do_poplevel (WHILE_COND_PREP (while_stmt));
- set_one_cleanup_loc (WHILE_COND_CLEANUP (while_stmt), input_location);
+ finish_loop_cond_prep (&WHILE_BODY (while_stmt),
+ &WHILE_COND_PREP (while_stmt),
+ WHILE_COND_CLEANUP (while_stmt));
+ else
+ WHILE_BODY (while_stmt) = do_poplevel (WHILE_BODY (while_stmt));
+ finish_loop_cond (&WHILE_COND (while_stmt), WHILE_BODY (while_stmt));
}
/* Begin a do-statement. Returns a newly created DO_STMT if
@@ -1584,17 +1645,16 @@ finish_for_stmt (tree for_stmt)
RANGE_FOR_BODY (for_stmt) = do_poplevel (RANGE_FOR_BODY (for_stmt));
else
{
- FOR_BODY (for_stmt)
- = (FOR_COND_PREP (for_stmt)
- ? pop_stmt_list (FOR_BODY (for_stmt))
- : do_poplevel (FOR_BODY (for_stmt)));
+ if (FOR_COND_PREP (for_stmt))
+ finish_loop_cond_prep (&FOR_BODY (for_stmt),
+ &FOR_COND_PREP (for_stmt),
+ FOR_COND_CLEANUP (for_stmt));
+ else
+ FOR_BODY (for_stmt) = do_poplevel (FOR_BODY (for_stmt));
if (FOR_COND (for_stmt))
finish_loop_cond (&FOR_COND (for_stmt),
FOR_EXPR (for_stmt) ? integer_one_node
: FOR_BODY (for_stmt));
- if (FOR_COND_PREP (for_stmt))
- FOR_COND_PREP (for_stmt) = do_poplevel (FOR_COND_PREP (for_stmt));
- set_one_cleanup_loc (FOR_COND_CLEANUP (for_stmt), input_location);
}
/* Pop the scope for the body of the loop. */
diff --git a/gcc/testsuite/g++.dg/expr/for9.C b/gcc/testsuite/g++.dg/expr/for9.C
new file mode 100644
index 000000000000..5f90a5c59f92
--- /dev/null
+++ b/gcc/testsuite/g++.dg/expr/for9.C
@@ -0,0 +1,25 @@
+// PR c++/118822
+// { dg-do compile }
+
+struct A { A (); ~A (); };
+bool baz ();
+
+void
+foo ()
+{
+ while (bool x = baz ())
+ {
+ lab:;
+ A a;
+ }
+}
+
+void
+bar ()
+{
+ for (bool y = baz (); bool x = baz (); y |= x)
+ {
+ lab:;
+ A a;
+ }
+}
diff --git a/gcc/tree-iterator.cc b/gcc/tree-iterator.cc
index eb0458a8e535..da69a60052d4 100644
--- a/gcc/tree-iterator.cc
+++ b/gcc/tree-iterator.cc
@@ -284,6 +284,28 @@ tsi_delink (tree_stmt_iterator *i)
i->ptr = next;
}
+/* Split a STATEMENT_LIST in I.contrainer into two, all statements
+ from the start until I.ptr inclusive will remain in the original
+ one, all statements after I.ptr are removed from that STATEMENT_LIST
+ and returned as a new STATEMENT_LIST. If I is the last statement,
+ an empty statement with LOC location is returned. */
+
+tree
+tsi_split_stmt_list (location_t loc, tree_stmt_iterator i)
+{
+ if (tsi_one_before_end_p (i))
+ return build_empty_stmt (loc);
+ tsi_next (&i);
+ tree ret = NULL_TREE;
+ while (!tsi_end_p (i))
+ {
+ tree t = tsi_stmt (i);
+ tsi_delink (&i);
+ append_to_statement_list_force (t, &ret);
+ }
+ return ret;
+}
+
/* Return the first expression in a sequence of COMPOUND_EXPRs, or in
a STATEMENT_LIST, disregarding DEBUG_BEGIN_STMTs, recursing into a
STATEMENT_LIST if that's the first non-DEBUG_BEGIN_STMT. */
diff --git a/gcc/tree-iterator.h b/gcc/tree-iterator.h
index e99134d1848e..cf5c6635fd9a 100644
--- a/gcc/tree-iterator.h
+++ b/gcc/tree-iterator.h
@@ -138,6 +138,7 @@ extern void tsi_link_after (tree_stmt_iterator *, tree,
enum tsi_iterator_update);
extern void tsi_delink (tree_stmt_iterator *);
+extern tree tsi_split_stmt_list (location_t, tree_stmt_iterator);
extern tree alloc_stmt_list (void);
extern void free_stmt_list (tree);
