[Bug target/32951] missed memcpy - movdqa optimization.

[rguenth at gcc dot gnu dot org]

--- Comment #8 from rguenth at gcc dot gnu dot org  2010-03-10 10:52 ---
(In reply to comment #7)
 current 4.4.x generates 'movdqa (%rdi), %xmm0' in both cases.
 4.2 branch is closed, 4.3 is near to close.
 can we close this bug as fixed?

GCC 4.4 creates movdqu (%rdi), %xmm0 for load_2 for me, so no (same as 4.5).


-- 

rguenth at gcc dot gnu dot org changed:

   What|Removed |Added

  Known to fail||4.4.3 4.5.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32951

[Bug target/32951] missed memcpy - movdqa optimization.

[rguenth at gcc dot gnu dot org]

--- Comment #9 from rguenth at gcc dot gnu dot org  2010-03-10 10:54 ---
Actually it does with the fixed aligned attribute.  Fixed.


-- 

rguenth at gcc dot gnu dot org changed:

   What|Removed |Added

 Status|NEW |RESOLVED
  Known to fail|4.4.3 4.5.0 |
  Known to work||4.4.3 4.5.0
 Resolution||FIXED
   Target Milestone|--- |4.4.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32951

[Bug target/32951] missed memcpy - movdqa optimization.

[pluto at agmk dot net]

--- Comment #7 from pluto at agmk dot net  2010-03-09 19:34 ---
current 4.4.x generates 'movdqa (%rdi), %xmm0' in both cases.
4.2 branch is closed, 4.3 is near to close.
can we close this bug as fixed?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32951

[Bug target/32951] missed memcpy - movdqa optimization.

[hjl dot tools at gmail dot com]

--- Comment #6 from hjl dot tools at gmail dot com  2008-05-29 04:45 ---
Type alignment is ignored for call. See PR 35771.


-- 

hjl dot tools at gmail dot com changed:

   What|Removed |Added

  BugsThisDependsOn||35771
Bug 32951 depends on bug 35771, which changed state.

Bug 35771 Summary: Call expander ignores type alignment
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35771

   What|Old Value   |New Value

 Status|RESOLVED|UNCONFIRMED
 Resolution|FIXED   |

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32951

[Bug target/32951] missed memcpy - movdqa optimization.

[hjl dot tools at gmail dot com]

--- Comment #5 from hjl dot tools at gmail dot com  2008-03-31 15:57 ---
Can you use

[EMAIL PROTECTED] tmp]$ cat v.c
#include emmintrin.h

__m128i load1( char const* buf )
{
  return _mm_loadu_si128 ((__m128i const *) buf);
}

__m128i load2( char const* buf )
{
  return _mm_load_si128 ((__m128i const *) buf);
}
[EMAIL PROTECTED] tmp]$ /usr/gcc-4.4/bin/gcc -O2 v.c -S 
[EMAIL PROTECTED] tmp]$ cat v.s
.file   v.c
.text
.p2align 4,,15
.globl load2
.type   load2, @function
load2:
.LFB519:
movdqa  (%rdi), %xmm0
ret
.LFE519:
.size   load2, .-load2
.p2align 4,,15
.globl load1
.type   load1, @function
load1:
.LFB518:
movdqu  (%rdi), %xmm0
ret
.LFE518:
.size   load1, .-load1


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32951

Re: [Bug target/32951] missed memcpy - movdqa optimization.

[Andrew Pinski]

On 6 Aug 2007 12:42:18 -, pluto at agmk dot net
[EMAIL PROTECTED] wrote:
 moreover i'm wondering why gcc uses movdqa for unaligned loads?

Because __m128i is assumed to be aligned.

-- Pinski

[Bug target/32951] missed memcpy - movdqa optimization.

[pluto at agmk dot net]

--- Comment #2 from pluto at agmk dot net  2007-08-06 12:42 ---
thanks for ths explanation about aligned attribute.

moreover i'm wondering why gcc uses movdqa for unaligned loads?
it should use movdqu for *((__m128i*)ptr) and _mm_set_epi8(ptr[15],...,ptr[0]).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32951

[Bug target/32951] missed memcpy - movdqa optimization.

[pluto at agmk dot net]

--- Comment #4 from pluto at agmk dot net  2007-08-06 12:56 ---
(In reply to comment #3)
 Subject: Re:  missed memcpy - movdqa optimization.
 
 On 6 Aug 2007 12:42:18 -, pluto at agmk dot net
 [EMAIL PROTECTED] wrote:
  moreover i'm wondering why gcc uses movdqa for unaligned loads?
 
 Because __m128i is assumed to be aligned.

so, as far i can see currently there's no way to generate movdqu load
with emmintrin.h and __builtin_memcpy( __m128i, unaligned_ptr, 16 )
and i must write a short inline assembly for this purpose.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32951

[Bug target/32951] missed memcpy - movdqa optimization.

[pinskia at gmail dot com]

--- Comment #3 from pinskia at gmail dot com  2007-08-06 12:43 ---
Subject: Re:  missed memcpy - movdqa optimization.

On 6 Aug 2007 12:42:18 -, pluto at agmk dot net
[EMAIL PROTECTED] wrote:
 moreover i'm wondering why gcc uses movdqa for unaligned loads?

Because __m128i is assumed to be aligned.

-- Pinski


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32951

[Bug target/32951] missed memcpy - movdqa optimization.

[pinskia at gcc dot gnu dot org]

--- Comment #1 from pinskia at gcc dot gnu dot org  2007-07-31 18:46 ---
(insn 7 6 8 t.c:15 (set (reg:DI 61)
(mem:DI (reg/v/f:DI 59 [ buf ]) [0 S8 A8])) -1 (nil))


See A8.

So the aligned attribute so not applying where you think it should be.
This is how you get the correct aligned attribute:
typedef char a __attribute__((aligned(16)));

typedef a const* aligned_byte_buffer;

And then after that memcpy is not using the vector registers:
(insn 7 6 8 t.c:17 (set (reg:DI 61)
(mem:DI (reg/v/f:DI 59 [ buf ]) [0 S8 A128])) -1 (nil))

(insn 8 7 9 t.c:17 (set (mem/c/i:DI (reg:DI 60) [0 m+0 S8 A128])
(reg:DI 61)) -1 (nil))

(insn 9 8 10 t.c:17 (set (reg:DI 62)
(mem:DI (plus:DI (reg/v/f:DI 59 [ buf ])
(const_int 8 [0x8])) [0 S8 A64])) -1 (nil))

(insn 10 9 0 t.c:17 (set (mem/c/i:DI (plus:DI (reg:DI 60)
(const_int 8 [0x8])) [0 m+8 S8 A64])
(reg:DI 62)) -1 (nil))


-- 

pinskia at gcc dot gnu dot org changed:

   What|Removed |Added

   Severity|normal  |enhancement
 Status|UNCONFIRMED |NEW
 Ever Confirmed|0   |1
   Last reconfirmed|-00-00 00:00:00 |2007-07-31 18:46:45
   date||


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32951