[Bug tree-optimization/43423] gcc should vectorize this loop through iteration range splitting

[pinskia at gcc dot gnu dot org]

--- Comment #2 from pinskia at gcc dot gnu dot org  2010-03-18 18:22 ---
Well it could be vectorized even without range splitting.  The issue is the
sinking of the store to a[i].


-- 

pinskia at gcc dot gnu dot org changed:

   What|Removed |Added

  Component|c   |tree-optimization


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43423

Re: [Bug tree-optimization/43423] gcc should vectorize this loop through iteration range splitting

[Sebastian Pop]

 Well it could be vectorized even without range splitting.  The issue is the
 sinking of the store to a[i].

You mean that the problem is the if-conversion of the stores
a[i] = ...

[Bug tree-optimization/43423] gcc should vectorize this loop through iteration range splitting

[sebpop at gmail dot com]

--- Comment #3 from sebpop at gmail dot com  2010-03-18 18:33 ---
Subject: Re:  gcc should vectorize this loop 
through iteration range splitting

 Well it could be vectorized even without range splitting.  The issue is the
 sinking of the store to a[i].

You mean that the problem is the if-conversion of the stores
a[i] = ...


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43423

[Bug tree-optimization/43423] gcc should vectorize this loop through iteration range splitting

[pinskia at gcc dot gnu dot org]

--- Comment #4 from pinskia at gcc dot gnu dot org  2010-03-18 18:38 ---
(In reply to comment #3)
 Subject: Re:  gcc should vectorize this loop 
 through iteration range splitting
 You mean that the problem is the if-conversion of the stores
 a[i] = ...

If we rewrite the code like:
int a[100], b[100], c[100];

void foo(int n, int mid)
{
  int i;
  for(i=0; in; i++)
{
  int t;
  int ai = a[i], bi = b[i], ci = c[i];
  if (i  mid)
t = ai + bi;
  else
t = ai + ci;
  a[i] = t;
}
}

--- CUT ---
This gets vectorized as we produce an if-cvt first.


-- 

pinskia at gcc dot gnu dot org changed:

   What|Removed |Added

 Status|UNCONFIRMED |NEW
 Ever Confirmed|0   |1
   Keywords||missed-optimization
   Last reconfirmed|-00-00 00:00:00 |2010-03-18 18:38:42
   date||


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43423

[Bug tree-optimization/43423] gcc should vectorize this loop through iteration range splitting

[spop at gcc dot gnu dot org]

--- Comment #5 from spop at gcc dot gnu dot org  2010-03-18 18:51 ---
Yes,
I think we should improve if-conversion to handle more complex cases.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43423