[Bug middle-end/27313] Does not emit conditional moves for stores

[rguenth at gcc dot gnu dot org]

--- Comment #7 from rguenth at gcc dot gnu dot org  2009-05-09 12:59 ---
Fixed.


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rguenth at gcc dot gnu dot org changed:

   What|Removed |Added

 Status|NEW |RESOLVED
 Resolution||FIXED
   Target Milestone|--- |4.3.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27313

[Bug middle-end/27313] Does not emit conditional moves for stores

[wilson at gcc dot gnu dot org]

--- Comment #6 from wilson at gcc dot gnu dot org  2009-05-09 01:21 ---
It looks like this was fixed by Michael Matz here:
http://gcc.gnu.org/ml/gcc-patches/2007-08/msg01978.html

This patch was added to gcc-4.3, and the gcc-4.2 branch is closed, so I think
this bug should be closed resolved.


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wilson at gcc dot gnu dot org changed:

   What|Removed |Added

 CC||wilson at gcc dot gnu dot
   ||org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27313

[Bug middle-end/27313] Does not emit conditional moves for stores

[steven at gcc dot gnu dot org]

--- Comment #5 from steven at gcc dot gnu dot org  2006-11-11 16:46 ---
You can't have if-converted stores at the tree level.

Forms of store motion, like the example of comment #2, ought to get implemented
at the tree level somewhen, though.  AFAIU this is currently very hard to do,
but the mem-ssa and new VN projects should help simplifying the job.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27313

[Bug middle-end/27313] Does not emit conditional moves for stores

[rguenth at gcc dot gnu dot org]

--- Comment #4 from rguenth at gcc dot gnu dot org  2006-09-21 13:07 ---
We have a flag (TREE_THIS_NOTRAP) to annotate ARRAY_REFs and INDIRECT_REFs.  It
could be used to guide tree-ifcvt to do the transformation.  Can we have
if-converted stores at the tree level at all?


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rguenth at gcc dot gnu dot org changed:

   What|Removed |Added

 CC||rguenth at gcc dot gnu dot
   ||org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27313

[Bug middle-end/27313] Does not emit conditional moves for stores

[dwarak dot rajagopal at amd dot com]

--- Comment #3 from dwarak dot rajagopal at amd dot com  2006-04-25 19:07 
---
Yes this is true. The example I posted was a simplest case where it fails.
Below mmight be a typical case where you have to do two stores. 
int cmov(int* A ,int B ,int C ,int* D ,int* E ,int F ,int g) {
  int k,f;
  for (k = 1; k <= 1000; k++) {
A[k] = B+C;
D[k] = C; /* D[k] may alias with A[k] */ 
g = D[k-1] + E[k-1];
if (g > A[k])  A[k]=g;  /* This is not converted to cmov*/
f += g;
  }
  return f;
}

In this case, you cannot reduce the number of stores (becasue D[k] may alias
with A[k]) but you still want the if conversion to take place. I think it is
good to have a mechanism to track if a memory is already been written in ifcvt.
I'm not sure how it can be done at this level though.  

-Dwarak


(In reply to comment #2)
> The other way of getting this is to have the code converted so there is only
> one store instead of two:
> 
> int cmov(int* A ,int B ,int C ,int* D ,int* E ,int F ,int g) {
>   int k,f;
>   for (k = 1; k <= 1000; k++) {
> int t = B+C;
> g = D[k-1] + E[k-1];
> if (g > t)  t=g;  /* This is not converted to cmov*/
> A[K] = t;
> f += g;
>   }
>   return f;
> }
> Which is most likely better anyways as one it is smaller.
> 


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27313

[Bug middle-end/27313] Does not emit conditional moves for stores

[pinskia at gcc dot gnu dot org]

--- Comment #2 from pinskia at gcc dot gnu dot org  2006-04-25 18:38 ---
The other way of getting this is to have the code converted so there is only
one store instead of two:

int cmov(int* A ,int B ,int C ,int* D ,int* E ,int F ,int g) {
  int k,f;
  for (k = 1; k <= 1000; k++) {
int t = B+C;
g = D[k-1] + E[k-1];
if (g > t)  t=g;  /* This is not converted to cmov*/
A[K] = t;
f += g;
  }
  return f;
}
Which is most likely better anyways as one it is smaller.


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pinskia at gcc dot gnu dot org changed:

   What|Removed |Added

 CC||pinskia at gcc dot gnu dot
   ||org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27313

[Bug middle-end/27313] Does not emit conditional moves for stores

[pinskia at gcc dot gnu dot org]

--- Comment #1 from pinskia at gcc dot gnu dot org  2006-04-25 17:38 ---
Confirmed, if cvt should have a way to track if a memory write has happened.


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pinskia at gcc dot gnu dot org changed:

   What|Removed |Added

 Status|UNCONFIRMED |NEW
  Component|c   |middle-end
 Ever Confirmed|0   |1
   Last reconfirmed|-00-00 00:00:00 |2006-04-25 17:38:13
   date||


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27313