[Bug bootstrap/99920] [10 regression] ICE building gcc 10 on power 7 BE

["rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99920

--- Comment #13 from Richard Biener <rguenth at gcc dot gnu.org> ---
So I can confirm the issue trying to build gcc10 packages for SLE11 ppc64
(after much massaging).  It works fine (past the failure point) on x86_64
with the same versioned host compiler.  It works fine when using gcc 4.8
as host compiler (also available on SLES11).

With the 4.3 based host compiler I see loads of

[  309s] In file included from ../../gcc/gimple-ssa-store-merging.c:168:
[  309s] ../../gcc/rtl.h: In function 'rtx_def* rtx_init(rtx_def*, rtx_code)':
[  309s] ../../gcc/rtl.h:2966: warning: invalid access to non-static data
member 'rtx_def::u' of NULL object
[  309s] ../../gcc/rtl.h:2966: warning: (perhaps the 'offsetof' macro was used
incorrectly)

also

[  625s] ../../gcc/cp/parser.c:31339:   instantiated from here
[  625s] ../../gcc/vec.h:1285: warning: invalid access to non-static data
member
 'vec<class_decl_loc_t::class_key_loc_t, va_heap, vl_embed>::m_vecdata' of NULL 
object
[  625s] ../../gcc/vec.h:1285: warning: (perhaps the 'offsetof' macro was used
incorrectly)
[  625s] ../../gcc/vec.h: In static member function 'static size_t vec<T, A,
vl_embed>::embedded_size(unsigned int) [with T = cp_expr, A = va_heap]':


when I bootstrap with STAGE1_CFLAGS="-O2 -g" then it gets past the failure
point as well (this does hint at some C++ initialization issue, IIRC those
plagued us a lot).  Note we're using STAGE1_CFLAGS="-O2 -g" for our
package builds (because we use known-good host compilers and to speed up
builds...) so we wouldn't have noticed this issue.

I'm still confident the error lies with our patched GCC 4.3.3 but I'm not
too interested in tracking the issue down ...