From: Bernd Schmidt <bschmidt@redhat.com>
To: Bernd Edlinger <bernd.edlinger@hotmail.de>,
Jakub Jelinek <jakub@redhat.com>
Cc: Eric Botcazou <ebotcazou@libertysurf.fr>,
Richard Sandiford <rdsandiford@googlemail.com>,
"gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>,
Matthew Fortune <Matthew.Fortune@imgtec.com>,
Nick Clifton <nickc@redhat.com>
Subject: Re: Is it OK for rtx_addr_can_trap_p_1 to attempt to compute the frame layout? (was Re: [PATCH] Skip re-computing the mips frame info after reload completed)
Date: Mon, 01 Feb 2016 12:18:00 -0000 [thread overview]
Message-ID: <56AF4D19.2000809@redhat.com> (raw)
In-Reply-To: <HE1PR07MB09056B7CC41C4FDB90C8FB39E4DB0@HE1PR07MB0905.eurprd07.prod.outlook.com>
On 01/29/2016 08:42 PM, Bernd Edlinger wrote:
> On 29.01.2016 16:47 Bernd Schmidt wrote:
>>
>> Yes. What is the problem with that? If we have (plus sfp const_int) at
>> any point before reload, we can check whether that offset is inside
>> frame_size. If it isn't or if the offset isn't known, it could trap.
>>
>>
>
> Usually we have "if (x==1234) { read MEM[FP+x]; }", so wo don't know,
> and then after reload: "if (x==1234) { read MEM[SP+x+sp_fp_offset]; }"
> but wait, in the if statement we know, that x==1234, so everything
> turns in one magic constant, and we have a totally new constant offset
> from the SP register "if (x==1234) { read MEM[SP+1234+sp_fp_offset]; }".
> Now if rtx_addr_can_trap_p(MEM[SP+1234+sp_fp_offset]) says it cannot
> trap we think we do not need the if at all => BANG.
What are you trying to say here? As far as I can tell this isn't a
problem with my proposed solution (set MEM_NOTRAP_P for valid SFP+x
offsets).
Bernd
next prev parent reply other threads:[~2016-02-01 12:18 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-23 13:25 [PATCH] Skip re-computing the mips frame info after reload completed Bernd Edlinger
2016-01-24 21:57 ` Matthew Fortune
2016-01-25 7:44 ` AW: " Bernd Edlinger
2016-01-25 19:57 ` Matthew Fortune
2016-01-26 21:18 ` Is it OK for rtx_addr_can_trap_p_1 to attempt to compute the frame layout? (was Re: [PATCH] Skip re-computing the mips frame info after reload completed) Richard Sandiford
2016-01-27 21:09 ` Bernd Edlinger
2016-01-28 22:17 ` Richard Sandiford
2016-01-29 17:54 ` Bernd Edlinger
2016-01-27 23:36 ` Eric Botcazou
2016-01-29 1:09 ` Bernd Schmidt
2016-01-29 15:18 ` Bernd Edlinger
2016-01-29 15:41 ` Jakub Jelinek
2016-01-29 15:47 ` Bernd Schmidt
2016-01-29 19:42 ` Bernd Edlinger
2016-02-01 12:18 ` Bernd Schmidt [this message]
2016-02-01 12:49 ` Richard Biener
2016-02-01 12:51 ` Bernd Schmidt
2016-02-01 13:10 ` Richard Biener
2016-02-01 13:19 ` AW: " Bernd Edlinger
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