On 03/01/2018 06:57 AM, Richard Biener wrote:
>
> This fixes another testcase that shows that our ANTIC iteration can
> fail to converge. The fix continues what we did with previous fixes,
> avoid spuriously removing stuff from the expression side of the sets.
> This time going full-in and allowing multiple expressions for the
> same value in the sets. I've added verification that the value-sets
> never grow during iteration which barfed on some of the related
> existing testcases and thus helped finishing this and fixing all
> places where we end up somewhat randomly choosing one or another
> expression to drop.
>
> I've verified with a GIMPLE testcase that if at insertion time
> we have multiple partially redundant expressions for the same value
> we insert/hoist it only once. So the only "bad" effect of the
> patch is that the expression part of the ANTIC sets grows -- by
> not throwing away random stuff we might also arrive at larger
> (value) solutions for ANTIC which means we may catch previously
> missed optimizations (or pessimizations as you know PRE...).
>
> I'm not entirely happy with the timing but I'm quite confident in
> the approach also (again) having heavily discussed this with Micha.
>
> Re-boostrap and regtest running on x86_64-unknown-linux-gnu.
>
> I managed to go into a different solution at the beginning asking
> for that pred/phiblock->edge cleanup and decided to leave that in...
>
> The new verification is guarded with flag_checking so if it would
> trigger but wouldn't result in not converging a release build
> should be not affected.
>
> Richard.
>
> 2018-01-03 Richard Biener <rguent...@suse.de>
>
> PR tree-optimization/84427
> * tree-ssa-pre.c (bitmap_remove_expr_from_set): Remove.
> (bitmap_set_subtract_values): Rewrite to handle multiple
> exprs per value.
> (clean): Likewise.
> (prune_clobbered_mems): Likewise.
> (phi_translate): Take edge instead of pred/phiblock.
> (phi_translate_1): Likewise.
> (phi_translate_set): Likewise. Insert all translated
> exprs for a value into the set, keeping possibly multiple
> expressions per value.
> (compute_antic_aux): Adjust for phi_translate changes.
> When intersecting union the expressions and prune those
> not in the final value set, keeping possibly multiple
> expressions per value. Do not use value-insertion
> for unioning ANTIC_OUT U EXP_GEN - TMP_GEN but merge
> all expressions. Add verification that the value-sets
> only shrink during iteration.
> (compute_partial_antic_aux): Adjust for the phi_translate changes.
> (do_pre_regular_insertion): Likewise.
> (do_pre_partial_partial_insertion): Likewise.
>
> * gcc.dg/torture/pr84427.c: New testcase.
Note most of my testers are failing with:
during GIMPLE pass: pre
../net/packet/af_packet.c: In function 'packet_setsockopt':
../net/packet/af_packet.c:3611:1: internal compiler error: in
compute_antic_aux, at tree-ssa-pre.c:2148
packet_setsockopt(struct socket *sock, int level, int optname, char
__user *optval, unsigned int optlen)
^~~~~~~~~~~~~~~~~
0xdfdb02 compute_antic_aux
../../../gcc/gcc/tree-ssa-pre.c:2148
0xdfdb02 compute_antic
../../../gcc/gcc/tree-ssa-pre.c:2364
0xdfdb02 execute
../../../gcc/gcc/tree-ssa-pre.c:4131
aarch, alpha, arm, nios, s390, riscv, mips, hppa, microblaze, i686,
powerpc. On a positive note, sh seems unaffected :-)
I'll try to get a testcase extracted.
jeff
