https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80032
--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
The patch causes some optimization regressions.
A different approach is to put the clobbers in non-conditional context -
something that is valid but with the clobber semantic cannot be done by the
middle-end. Instead we can do this at gimplification time with, say,
Index: gcc/gimplify.c
===================================================================
--- gcc/gimplify.c (revision 246216)
+++ gcc/gimplify.c (working copy)
@@ -6288,10 +6288,13 @@ gimplify_cleanup_point_expr (tree *expr_
/* Insert a cleanup marker for gimplify_cleanup_point_expr. CLEANUP
is the cleanup action required. EH_ONLY is true if the cleanup should
- only be executed if an exception is thrown, not on normal exit. */
+ only be executed if an exception is thrown, not on normal exit.
+ If FORCE_UNCOND is true perform the cleanup unconditionally; this is
+ only valid for clobbers. */
static void
-gimple_push_cleanup (tree var, tree cleanup, bool eh_only, gimple_seq *pre_p)
+gimple_push_cleanup (tree var, tree cleanup, bool eh_only, gimple_seq *pre_p,
+ bool force_uncond = false)
{
gimple *wce;
gimple_seq cleanup_stmts = NULL;
@@ -6301,7 +6304,8 @@ gimple_push_cleanup (tree var, tree clea
if (seen_error ())
return;
- if (gimple_conditional_context ())
+ if (gimple_conditional_context ()
+ && ! force_uncond)
{
/* If we're in a conditional context, this is more complex. We only
want to run the cleanup if we actually ran the initialization that
@@ -6426,11 +6430,7 @@ gimplify_target_expr (tree *expr_p, gimp
NULL);
TREE_THIS_VOLATILE (clobber) = true;
clobber = build2 (MODIFY_EXPR, TREE_TYPE (temp), temp, clobber);
- if (cleanup)
- cleanup = build2 (COMPOUND_EXPR, void_type_node, cleanup,
- clobber);
- else
- cleanup = clobber;
+ gimple_push_cleanup (temp, clobber, false, pre_p, true);
}
if (asan_poisoned_variables && dbg_cnt (asan_use_after_scope))
{
which brings down stack usage to GCC 5 levels (so is even better than the
other patch).
