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On 09/27/11 09:00, Richard Guenther wrote:
>> The thing to remember is jump threading is tasked detecting
>> cases where the control statement has a predetermined destination
>> utilizing path sensitive information. Expanding it to do
>> general path
On Tue, Sep 27, 2011 at 4:56 PM, Jeff Law wrote:
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> On 09/27/11 01:30, Richard Guenther wrote:
>
>>
>>> It knows something about prephitmp.6_1 and thus could simplify
>>> D.2734_9 = prephitmp_6.1 & D.2732_7; to D.2734_9 = D.2732_7; But
>>> admitte
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On 09/27/11 01:30, Richard Guenther wrote:
>
>> It knows something about prephitmp.6_1 and thus could simplify
>> D.2734_9 = prephitmp_6.1 & D.2732_7; to D.2734_9 = D.2732_7; But
>> admittedly I have no idea if DOM tries to simplify things other
>>
On Mon, Sep 26, 2011 at 6:42 PM, Jeff Law wrote:
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> On 09/26/11 05:00, Richard Guenther wrote:
>> On Mon, Sep 26, 2011 at 9:39 AM, Jiangning Liu
>> wrote:
> * Without PRE,
>
> Path1: movl $2, %eax cmpl $1, %eax je .L3
>
> -Original Message-
> From: Jeff Law [mailto:l...@redhat.com]
> Sent: Tuesday, September 27, 2011 12:43 AM
> To: Richard Guenther
> Cc: Jiangning Liu; gcc@gcc.gnu.org
> Subject: Re: A case that PRE optimization hurts performance
>
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On 09/26/11 05:00, Richard Guenther wrote:
> On Mon, Sep 26, 2011 at 9:39 AM, Jiangning Liu
> wrote:
* Without PRE,
Path1: movl$2, %eax cmpl$1, %eax je .L3
Path2: movb$3, %al cmpl$1, %eax je .L3
>>>
On Mon, Sep 26, 2011 at 9:39 AM, Jiangning Liu wrote:
>> > * Without PRE,
>> >
>> > Path1:
>> > movl $2, %eax
>> > cmpl $1, %eax
>> > je .L3
>> >
>> > Path2:
>> > movb $3, %al
>> > cmpl $1, %eax
>> > je .L3
>> >
>> > Path3:
>> >
> > * Without PRE,
> >
> > Path1:
> > movl $2, %eax
> > cmpl $1, %eax
> > je .L3
> >
> > Path2:
> > movb $3, %al
> > cmpl $1, %eax
> > je .L3
> >
> > Path3:
> > cmpl $1, %eax
> > jne .L14
> >
> > * With PRE,
> >
>
$1, %eax
> jne .L14
>
> * With PRE,
>
> Path1:
> movl $1, %ebx
> movl $2, %eax
> testb %bl, %bl
> je .L3
>
> Path2:
> movl $1, %ebx
> movb $3, %al
> testb %bl, %bl
>
ts?
Thanks,
-Jiangning
> -Original Message-
> From: Richard Guenther [mailto:richard.guent...@gmail.com]
> Sent: Tuesday, August 02, 2011 5:23 PM
> To: Jiangning Liu
> Cc: gcc@gcc.gnu.org
> Subject: Re: A case that PRE optimization hurts performance
>
> On Tue, A
On Tue, 2 Aug 2011 10:37:03 +0800, Jiangning Liu wrote:
Hi,
For the following simple test case, PRE optimization hoists
computation
(s!=1) into the default branch of the switch statement, and finally
causes
very poor code generation. This problem occurs in both X86 and ARM,
and I
believe it
On Tue, Aug 2, 2011 at 4:37 AM, Jiangning Liu wrote:
> Hi,
>
> For the following simple test case, PRE optimization hoists computation
> (s!=1) into the default branch of the switch statement, and finally causes
> very poor code generation. This problem occurs in both X86 and ARM, and I
> believe
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