On 8/23/21 4:16 PM, Jakub Jelinek wrote:
Hi!
The removal of remove_zero_width_bit_fields, in addition to triggering
some ABI issues that need solving anyway (ABI incompatibility between
C and C++) also resulted in UB inside of gcc, we now call build_zero_init
which calls build_int_cst on an integral type with TYPE_PRECISION of 0.
Fixed by ignoring the zero width bitfields. I understand
build_value_init_noctor wants to initialize to 0 even unnamed bitfields
(of non-zero width), at least until we have some CONSTRUCTOR flag that says
that even all the padding bits should be cleared.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
OK.
2021-08-23 Jakub Jelinek <ja...@redhat.com>
PR c++/102019
* init.c (build_value_init_noctor): Ignore unnamed zero-width
bitfields.
--- gcc/cp/init.c.jj 2021-07-29 13:24:42.698012879 +0200
+++ gcc/cp/init.c 2021-08-23 14:43:08.791947395 +0200
@@ -427,6 +427,11 @@ build_value_init_noctor (tree type, tsub
== NULL_TREE))
continue;
+ /* Ignore unnamed zero-width bitfields. */
+ if (DECL_UNNAMED_BIT_FIELD (field)
+ && integer_zerop (DECL_SIZE (field)))
+ continue;
+
/* We could skip vfields and fields of types with
user-defined constructors, but I think that won't improve
performance at all; it should be simpler in general just
Jakub
