@gcc.gnu.org
Subject: RE: No TBAA before ptr_derefs_may_alias_p?
On January 31, 2014 6:01:36 PM GMT+01:00, Bingfeng Mei b...@broadcom.com
wrote:
Unfortunately this patch doesn't work because the memory dependency is
Anti in this
case.
Why TBAA cannot handle anti- output- dependencies? I check GCC
On Mon, Feb 03, 2014 at 09:51:01AM +, Bingfeng Mei wrote:
If it is just for C++ placement new, why don't implement it as a lang_hook.
Now other languages such as C have to be made conservative and produce worse
code.
Even in C++ code you don't use placement new that often, so e.g. by
On 02/03/2014 10:59 AM, Jakub Jelinek wrote:
On Mon, Feb 03, 2014 at 09:51:01AM +, Bingfeng Mei wrote:
If it is just for C++ placement new, why don't implement it as a lang_hook.
Now other languages such as C have to be made conservative and produce worse
code.
Even in C++ code you don't
On Mon, 3 Feb 2014, Jakub Jelinek wrote:
On Mon, Feb 03, 2014 at 09:51:01AM +, Bingfeng Mei wrote:
If it is just for C++ placement new, why don't implement it as a lang_hook.
Now other languages such as C have to be made conservative and produce worse
code.
But if you combine a C++
On Mon, 3 Feb 2014, Florian Weimer wrote:
On 02/03/2014 10:59 AM, Jakub Jelinek wrote:
On Mon, Feb 03, 2014 at 09:51:01AM +, Bingfeng Mei wrote:
If it is just for C++ placement new, why don't implement it as a
lang_hook.
Now other languages such as C have to be made conservative
On Mon, 3 Feb 2014, Richard Biener wrote:
And note that for the case in question we
can derive non-aliasing because with
p[i] += q[i];
p[i] is both read _and_ written in the same iteration thus
it cannot have the dynamic type of q[i] before it's stored
into. Of course data-dependence
Weimer
Cc: Jakub Jelinek; Bingfeng Mei; gcc@gcc.gnu.org
Subject: Re: No TBAA before ptr_derefs_may_alias_p?
On Mon, 3 Feb 2014, Florian Weimer wrote:
On 02/03/2014 10:59 AM, Jakub Jelinek wrote:
On Mon, Feb 03, 2014 at 09:51:01AM +, Bingfeng Mei wrote:
If it is just for C++ placement new
Subject: Re: No TBAA before ptr_derefs_may_alias_p?
On Mon, 3 Feb 2014, Richard Biener wrote:
And note that for the case in question we
can derive non-aliasing because with
p[i] += q[i];
p[i] is both read _and_ written in the same iteration thus
it cannot have the dynamic type of q[i] before
Subject: Re: No TBAA before ptr_derefs_may_alias_p?
On Mon, 3 Feb 2014, Florian Weimer wrote:
On 02/03/2014 10:59 AM, Jakub Jelinek wrote:
On Mon, Feb 03, 2014 at 09:51:01AM +, Bingfeng Mei wrote:
If it is just for C++ placement new, why don't implement it as a
lang_hook.
Now
[mailto:rguent...@suse.de]
Sent: 03 February 2014 13:16
To: Bingfeng Mei
Cc: Florian Weimer; Jakub Jelinek; gcc@gcc.gnu.org
Subject: RE: No TBAA before ptr_derefs_may_alias_p?
On Mon, 3 Feb 2014, Bingfeng Mei wrote:
For the following code, why can load be moved before store instruction?
TBAA still
already have done that (PR60043)
Richard.
Bingfeng
-Original Message-
From: Richard Biener [mailto:rguent...@suse.de]
Sent: 03 February 2014 13:16
To: Bingfeng Mei
Cc: Florian Weimer; Jakub Jelinek; gcc@gcc.gnu.org
Subject: RE: No TBAA before ptr_derefs_may_alias_p?
On Mon, 3 Feb
Hi,
I got this simple example to vectorize. Somehow, GCC (4.8) generates loop
version because
it cannot determine alias between acc[i] write and x[i].real read. It is pretty
obvious to me that they are not aliased based on TBAA information.
typedef struct
{
short real;
short imag;
}
On 1/31/14 4:02 PM, Bingfeng Mei wrote:
Hi,
I got this simple example to vectorize. Somehow, GCC (4.8) generates loop
version because
it cannot determine alias between acc[i] write and x[i].real read. It is
pretty obvious to me that they are not aliased based on TBAA information.
typedef
Thanks, Richard,
I will prepare a patch with test as well as filing a bug.
Bingfeng
-Original Message-
From: Richard Biener [mailto:rguent...@suse.de]
Sent: 31 January 2014 15:24
To: Bingfeng Mei; gcc@gcc.gnu.org
Subject: Re: No TBAA before ptr_derefs_may_alias_p?
On 1/31/14 4:02 PM
@gcc.gnu.org
Subject: Re: No TBAA before ptr_derefs_may_alias_p?
On 1/31/14 4:02 PM, Bingfeng Mei wrote:
Hi,
I got this simple example to vectorize. Somehow, GCC (4.8) generates loop
version because
it cannot determine alias between acc[i] write and x[i].real read. It is
pretty obvious to me
location to
change by a store.
That in turn is the only sensible way of supporting c++ placement new.
Richard.
Bingfeng
-Original Message-
From: Richard Biener [mailto:rguent...@suse.de]
Sent: 31 January 2014 15:24
To: Bingfeng Mei; gcc@gcc.gnu.org
Subject: Re: No TBAA before
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