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From: "spark at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/32296] [4.3 Regression] Bootstrap failure in stage1 on hppa*-*-*
Date: Tue, 12 Jun 2007 23:07:00 -0000 [thread overview]
Message-ID: <20070612230735.1135.qmail@sourceware.org> (raw)
In-Reply-To: <bug-32296-276@http.gcc.gnu.org/bugzilla/>
------- Comment #6 from spark at gcc dot gnu dot org 2007-06-12 23:07 -------
(In reply to comment #5)
> Subject: Re: [4.3 Regression] Bootstrap failure in stage1 on hppa*-*-*
>
> > @@ -4384,7 +4385,7 @@ hppa_can_use_return_insn_p (void)
> > {
> > return (reload_completed
> > && (compute_frame_size (get_frame_size (), 0) ? 0 : 1)
> > - && ! df_regs_ever_live_p (2)
> > + && df_hard_reg_used_count (2) == 1
> > && ! frame_pointer_needed);
> > }
>
> Don't understand difference between df_regs_ever_live_p and
> f->hard_regs_live_count, and why you are checking for a count of 1.
hppa_can_use_return_insn_p() is called
from "return" insn pattern in pa.md.
The pattern looks:
(define_insn "return"
[(return)
(use (reg:SI 2))
(const_int 0)]
"hppa_can_use_return_insn_p ()"
"*
i.e. there's a use of reg 2.
Before dataflow branch got merged, regs_ever_live(2) was not true
for reg 2, even though it is used at the return (hence it's live
throughout the function body) - unless there's some other use
within the function.
Now, with df, we always have the correct and precise regs_ever_live.
Since the condition hppa_can_use_return_p() is checking
is really that there are no other insn that uses reg 2
AND since we know the pattern has a use of reg 2,
checking the number of use count to be 1
checks effectively the same assertion.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32296
next prev parent reply other threads:[~2007-06-12 23:07 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-06-12 0:33 [Bug regression/32296] New: " danglin at gcc dot gnu dot org
2007-06-12 0:40 ` [Bug regression/32296] " pinskia at gcc dot gnu dot org
2007-06-12 0:44 ` [Bug rtl-optimization/32296] [4.3 Regression] " pinskia at gcc dot gnu dot org
2007-06-12 1:01 ` spark at gcc dot gnu dot org
2007-06-12 1:14 ` spark at gcc dot gnu dot org
2007-06-12 1:38 ` dave at hiauly1 dot hia dot nrc dot ca
2007-06-12 21:43 ` spark at gcc dot gnu dot org
2007-06-12 23:00 ` dave at hiauly1 dot hia dot nrc dot ca
2007-06-12 23:07 ` spark at gcc dot gnu dot org [this message]
2007-06-12 23:31 ` dave at hiauly1 dot hia dot nrc dot ca
2007-06-13 3:45 ` dave at hiauly1 dot hia dot nrc dot ca
2007-06-13 3:48 ` spark at gcc dot gnu dot org
2007-06-13 13:28 ` dave at hiauly1 dot hia dot nrc dot ca
2007-06-14 3:54 ` spark at gcc dot gnu dot org
2007-06-14 21:05 ` dave at hiauly1 dot hia dot nrc dot ca
2007-06-15 20:05 ` dave at hiauly1 dot hia dot nrc dot ca
2007-06-19 19:57 ` dave at hiauly1 dot hia dot nrc dot ca
2007-06-19 20:10 ` hjl at lucon dot org
2007-06-19 20:40 ` dave at hiauly1 dot hia dot nrc dot ca
2007-06-19 23:30 ` danglin at gcc dot gnu dot org
2007-06-19 23:32 ` danglin at gcc dot gnu dot org
2007-06-21 2:56 ` dave at hiauly1 dot hia dot nrc dot ca
2007-06-21 8:53 ` tbm at cyrius dot com
2007-06-29 18:44 ` mmitchel at gcc dot gnu dot org
2007-06-30 15:20 ` danglin at gcc dot gnu dot org
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