Hi!
On Mon, Jun 03, 2024 at 04:55:05PM +0200, Jakub Jelinek wrote:
> PCH doesn't work properly in --enable-host-pie configurations on
> powerpc*-linux*.
PCH and PIE, two of my favourites ;-)
> For PCH though it actually results in saving those huge arrays (one is
> 130832 bytes, another 81568 bytes) into the .gch files and loading them back
> in full. While the bifname and attr_string and next pointers are marked as
> GTY((skip)), they are actually saved to point to the .rodata and .data
> sections of the process which writes the PCH, but because cc1/cc1plus etc.
> are position independent executables with --enable-host-pie, when it is
> loaded from the PCH file, it can point in a completely different addresses
> where nothing is mapped at all or some random different thing appears at.
Yuck.
> So, either we'd need to add some further GTY extensions, or the following
> patch instead reworks it such that the fntype members which were the only
> reason for PCH in those arrays are moved to separate arrays.
And that just sidesteps the limitation in PCH?
> void
> rs6000_init_generated_builtins ()
> {
> + bifdata *rs6000_builtin_info_p;
> + tree *rs6000_builtin_info_fntype_p;
> + ovlddata *rs6000_instance_info_p;
> + tree *rs6000_instance_info_fntype_p;
> + ovldrecord *rs6000_overload_info_p;
> + __asm ("" : "=r" (rs6000_builtin_info_p) : "0" (rs6000_builtin_info));
Bah.
It should not be called _p of course, it is not a predicate. And
relying on the operand tie to not have to do a much more obvious
assignment, please don't. Just *do* write assignments, and then use
a simple "+r"?
But you call this a hack anyway, you wouldn't propose to actually
include this patch :-)
> Bootstrapped/regtested on powerpc64le-linux and powerpc64-linux (-m32/-m64
> testing there), ok for trunk and after a while for release branches?
Yes please. What nastiness. Thanks for dealing with it!
Segher
> 2024-06-03 Jakub Jelinek <ja...@redhat.com>
>
> PR target/115324
> * config/rs6000/rs6000-gen-builtins.cc (write_decls): Remove
> GTY markup from struct bifdata and struct ovlddata and remove their
> fntype members. Change next member in struct ovlddata and
> first_instance member of struct ovldrecord to have int type rather
> than struct ovlddata *. Remove GTY markup from rs6000_builtin_info
> and rs6000_instance_info arrays, declare new
> rs6000_builtin_info_fntype and rs6000_instance_info_fntype arrays,
> which have GTY markup.
> (write_bif_static_init): Adjust for the above changes.
> (write_ovld_static_init): Likewise.
> (write_init_bif_table): Likewise.
> (write_init_ovld_table): Likewise.
> * config/rs6000/rs6000-builtin.cc (rs6000_init_builtins): Likewise.
> * config/rs6000/rs6000-c.cc (find_instance): Likewise. Make static.
> (altivec_resolve_overloaded_builtin): Adjust for the above changes.
