[Bug tree-optimization/18892] missed optimization with and ==

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=18892
Bug 18892 depends on bug 15459, which changed state.

Bug 15459 Summary: [meta-bug] there should be a tree combiner like the rtl one
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=15459

   What|Removed |Added

 Status|ASSIGNED|RESOLVED
 Resolution|--- |FIXED

[Bug tree-optimization/18892] missed optimization with and ==

[pinskia at gcc dot gnu dot org]

--- Comment #8 from pinskia at gcc dot gnu dot org  2007-07-01 00:12 ---
This was fixed with one of the forwprop patches, I don't know which one though.


-- 

pinskia 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=18892

[Bug tree-optimization/18892] missed optimization with and ==

[pinskia at gcc dot gnu dot org]

--- Additional Comments From pinskia at gcc dot gnu dot org  2005-07-12 
21:27 ---
It might be a while for me to rewrite the tree combiner so unassigning for now.

-- 
   What|Removed |Added

 AssignedTo|pinskia at gcc dot gnu dot  |unassigned at gcc dot gnu
   |org |dot org
 Status|ASSIGNED|NEW


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18892

[Bug tree-optimization/18892] missed optimization with and ==

[pinskia at gcc dot gnu dot org]

--- Additional Comments From pinskia at gcc dot gnu dot org  2004-12-11 
07:19 ---
(In reply to comment #5)
 (In reply to comment #4)
  when I compile this program with mainline.  Isnt this what you claimed it 
  should
  be compiled to?  or are you claiming it should be optimized to 'return 0'?
 
 I am claiming it should be compiled to return 0.  The full testcase which 
 is closer to
 what shows up in GCC is:
 
 void f(int a)
 {
   int i = a  -129;
   if (i == 144)
 link_error ();
 }

The testcase works but for the wrong reason (we call fold for COND_EXPR after 
out of ssa because
of tree_cleanup_cfg).

Here is a testcase which fails though:

void g(int)  __attribute__((noinline);
void g(int a) { a+=2; }

void f(int a)
{
  int i = a  -129;
  g(i);
  if (i == 144)
link_error ();
}

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18892

[Bug tree-optimization/18892] missed optimization with and ==

[amacleod at redhat dot com]

--- Additional Comments From amacleod at redhat dot com  2004-12-09 14:34 
---
Im confused.  I see a final form of:

f (a)
{
bb 0:
  return (a  -129) == 144;
}


when I compile this program with mainline.  Isnt this what you claimed it should
be compiled to?  or are you claiming it should be optimized to 'return 0'?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18892

[Bug tree-optimization/18892] missed optimization with and ==

[pinskia at gcc dot gnu dot org]

--- Additional Comments From pinskia at gcc dot gnu dot org  2004-12-09 
14:38 ---
(In reply to comment #4)
 when I compile this program with mainline.  Isnt this what you claimed it 
 should
 be compiled to?  or are you claiming it should be optimized to 'return 0'?

I am claiming it should be compiled to return 0.  The full testcase which is 
closer to
what shows up in GCC is:

void f(int a
{
  int i = a  -129;
  if (i == 144)
link_error ();
]

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18892

[Bug tree-optimization/18892] missed optimization with and ==

[dnovillo at redhat dot com]

--- Additional Comments From dnovillo at redhat dot com  2004-12-08 20:28 
---
Subject: Re:  New: missed SRA of a block copy

pinskia at gcc dot gnu dot org wrote:
 The following function:
 int f(int a)
 {
   int i = a  -129;
   return i == 144;
 }
 Should be compiled to:
 int f1(int a)
 {
   return (a  -129) == 144; // aka return 0;
 }
 
 Yes this shows up in real code (gcc), found while testing out my tree 
 combiner.
 
Hmm?  What does SRA have to do with anything here?


Diego.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18892

[Bug tree-optimization/18892] missed optimization with and ==

[pinskia at gcc dot gnu dot org]

--- Additional Comments From pinskia at gcc dot gnu dot org  2004-12-08 
20:31 ---
(In reply to comment #2)
 Subject: Re:  New: missed SRA of a block copy
 
 Hmm?  What does SRA have to do with anything here?

Nothing I had messed up on the summary and already changed
it after seeing that I had messed up on it.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18892