[Bug target/21588] New: x86 machine builtins do not have any const/pure attributes set

[Bug target/21588] New: x86 machine builtins do not have any const/pure attributes set

[steven at gcc dot gnu dot org]

Consider this snippet: 
 
typedef float v4sf __attribute__ ((vector_size (16))); 
float global; 
float 
waste_global (float p[4]) 
{ 
  __builtin_ia32_loadups (p); 
  global += 1.0; 
} 
 
GCC now thinks __builtin_ia32_loadups clobbers global: 
 
waste_global (pD.1564) 
{ 
  floatD.28 D.1568; 
  floatD.28 global.0D.1567; 
 
  # BLOCK 0 
  # PRED: ENTRY [100.0%]  (fallthru,exec) 
  #   globalD.1563_6 = V_MAY_DEF <globalD.1563_2>; 
  __builtin_ia32_loadups (pD.1564_1); 
  #   VUSE <globalD.1563_6>; 
  global.0D.1567_3 = globalD.1563; 
  D.1568_4 = global.0D.1567_3 + 1.0e+0; 
  #   globalD.1563_5 = V_MUST_DEF <globalD.1563_6>; 
  globalD.1563 = D.1568_4; 
  return; 
  # SUCC: EXIT [100.0%] 
 
} 
 
 
This is a bit silly, if we encourage people to use builtins instead 
of inline assembly.

-- 
           Summary: x86 machine builtins do not have any const/pure
                    attributes set
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P2
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: steven at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org,hubicka at gcc dot gnu
                    dot org,rth at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21588

[Bug target/21588] x86 machine builtins do not have any const/pure attributes set

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-15 18:05 -------
Confirmed, I cannot remember or not if the rs6000/altivec builtins were fixed or not.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pinskia at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
 GCC target triplet|                            |i?86-*-*, x86_64-*-*
   Last reconfirmed|0000-00-00 00:00:00         |2005-05-15 18:05:01
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21588

[Bug target/21588] x86 machine builtins do not have any const/pure attributes set

[rth at gcc dot gnu dot org]

------- Additional Comments From rth at gcc dot gnu dot org  2005-05-16 18:14 -------
True.  I remember trying this, though, and in practice all it did was increase
register pressure.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21588

[Bug target/21588] x86 machine builtins do not have any const/pure attributes set

[rth at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21588

[Bug target/21588] x86 machine builtins do not have any const/pure attributes set

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-09-29 04:12 -------
Making this depend on the "need a new ra" bug.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
  BugsThisDependsOn|                            |18427


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21588

[Bug target/21588] x86 machine builtins do not have any const/pure attributes set

[hubicka at ucw dot cz]

------- Additional Comments From hubicka at ucw dot cz  2005-09-30 10:38 -------
Subject: Re:  x86 machine builtins do not have any const/pure attributes set

> 
> ------- Additional Comments From pinskia at gcc dot gnu dot org  2005-09-29 04:12 -------
> Making this depend on the "need a new ra" bug.

Does the code quality regression still hold even after libcalls was
removed?  These definitly was one of reason for ineffencities in
pure/const function call code generation.

Honza
> 
> -- 
>            What    |Removed                     |Added
> ----------------------------------------------------------------------------
>   BugsThisDependsOn|                            |18427
> 
> 
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21588
> 
> ------- You are receiving this mail because: -------
> You are on the CC list for the bug, or are watching someone who is.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21588

[Bug target/21588] x86 machine builtins do not have any const/pure attributes set

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-09-30 12:56 -------
(In reply to comment #5)
> Does the code quality regression still hold even after libcalls was
> removed?  These definitly was one of reason for ineffencities in
> pure/const function call code generation.

I doubt it since these expanded into RTL instruction and there is no call at the rtl level.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21588

[Bug target/21588] x86 machine builtins do not have any const/pure attributes set

[hubicka at ucw dot cz]

------- Additional Comments From hubicka at ucw dot cz  2005-09-30 13:38 -------
Subject: Re:  x86 machine builtins do not have any const/pure attributes set

> 
> ------- Additional Comments From pinskia at gcc dot gnu dot org  2005-09-30 12:56 -------
> (In reply to comment #5)
> > Does the code quality regression still hold even after libcalls was
> > removed?  These definitly was one of reason for ineffencities in
> > pure/const function call code generation.
> 
> I doubt it since these expanded into RTL instruction and there is no call at the rtl level.
Hmm, right ;)  Should look deper into PR before responding...

Honza


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21588