On Thu, 7 Dec 2023, Jakub Jelinek wrote:
> On Thu, Dec 07, 2023 at 09:36:22AM +0100, Jakub Jelinek wrote:
> > So, one way to fix the LRA issue would be just to use
> > lra_insn_recog_data_len = index * 3U / 2;
> > if (lra_insn_recog_data_len <= index)
> > lra_insn_recog_data_len = index + 1;
> > basically do what vec.cc does. I thought we can do better for
> > both vec.cc and LRA on 64-bit hosts even without growing the allocated
> > counters, but now that I look at it again, perhaps we can't.
> > The above overflows already with original alloc or lra_insn_recog_data_len
> > 0x55555556, where 0x5555555 * 3U / 2 is still 0x7fffffff
> > and so representable in the 32-bit, but 0x55555556 * 3U / 2 is
> > 1. I thought (and the patch implements it) that we could use
> > alloc * (size_t) 3 / 2 so that on 64-bit hosts it wouldn't overflow
> > that quickly, but 0x55555556 * (size_t) 3 / 2 there is 0x80000001
> > which is still ok in unsigned, but given that vec.h then stores the
> > counter into unsigned m_alloc:31; bit-field, it is too much.
> >
> > The patch below is what I've actually bootstrapped/regtested on
> > x86_64-linux and i686-linux, but given the above I think I should drop
> > the vec.cc hunk and change (size_t) 3 in the LRA hunk to 3U.
>
> Here is so far untested adjusted patch, which does the computation
> just in unsigned int rather than size_t, because doing it in size_t
> wouldn't improve things.
OK, but ...
> 2023-12-07 Jakub Jelinek <ja...@redhat.com>
>
> PR middle-end/112411
> * params.opt (-param=min-nondebug-insn-uid=): Add
> IntegerRange(0, 1073741824).
> * lra.cc (check_and_expand_insn_recog_data): Use 3U rather than 3
> in * 3 / 2 computation and if the result is smaller or equal to
> index, use index + 1.
>
> * gcc.dg/params/blocksort-part.c: Add dg-skip-if for
> --param min-nondebug-insn-uid=1073741824.
what's this change for? Do we test the actual param limit? Can you
skip for the param without specifying the actual upper bound?
Thanks,
Richard.
> --- gcc/params.opt.jj 2023-11-02 07:49:18.010852541 +0100
> +++ gcc/params.opt 2023-12-06 18:55:57.045420935 +0100
> @@ -779,7 +779,7 @@ Common Joined UInteger Var(param_min_loo
> The minimum threshold for probability of semi-invariant condition statement
> to trigger loop split.
>
> -param=min-nondebug-insn-uid=
> -Common Joined UInteger Var(param_min_nondebug_insn_uid) Param
> +Common Joined UInteger Var(param_min_nondebug_insn_uid) Param
> IntegerRange(0, 1073741824)
> The minimum UID to be used for a nondebug insn.
>
> -param=min-size-for-stack-sharing=
> --- gcc/lra.cc.jj 2023-12-05 13:17:29.642260866 +0100
> +++ gcc/lra.cc 2023-12-06 19:52:01.759241999 +0100
> @@ -768,7 +768,9 @@ check_and_expand_insn_recog_data (int in
> if (lra_insn_recog_data_len > index)
> return;
> old = lra_insn_recog_data_len;
> - lra_insn_recog_data_len = index * 3 / 2 + 1;
> + lra_insn_recog_data_len = index * 3U / 2;
> + if (lra_insn_recog_data_len <= index)
> + lra_insn_recog_data_len = index + 1;
> lra_insn_recog_data = XRESIZEVEC (lra_insn_recog_data_t,
> lra_insn_recog_data,
> lra_insn_recog_data_len);
> --- gcc/testsuite/gcc.dg/params/blocksort-part.c.jj 2020-01-12
> 11:54:37.463397567 +0100
> +++ gcc/testsuite/gcc.dg/params/blocksort-part.c 2023-12-07
> 08:46:11.656974144 +0100
> @@ -1,4 +1,5 @@
> /* { dg-skip-if "AArch64 does not support these bounds." { aarch64*-*-* } {
> "--param stack-clash-protection-*" } } */
> +/* { dg-skip-if "For 32-bit hosts such param is too much and even for 64-bit
> might require hundreds of GB of RAM" { *-*-* } { "--param
> min-nondebug-insn-uid=1073741824" } } */
>
> /*-------------------------------------------------------------*/
> /*--- Block sorting machinery ---*/
>
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
