[Bug tree-optimization/15457] New: [tree-ssa] Convert a sign bit testing into "a < 0"

[Bug tree-optimization/15457] New: [tree-ssa] Convert a sign bit testing into "a < 0"

[kazu at cs dot umass dot edu]

Convert a sign bit testing into "a < 0".

void bar (void);

void
foo (signed int a)
{
  signed int b = a & (signed int) 0x80000000;
  if (b)
    bar ();
}

void
baz (signed int a)
{
  signed int b = a & 0x80000000;
  if (b)
    bar ();
}

void
baa (signed int a)
{
  signed int b = a & (1 << 31);
  if (b)
    bar ();
}

The last tree-ssa form looks like:

;; Function foo (foo)

foo (a)
{
  int b;

<bb 0>:
  b_2 = a_1 & -2147483648;
  if (b_2 != 0) goto <L0>; else goto <L1>;

<L0>:;
  bar () [tail call];

<L1>:;
  return;

}



;; Function baz (baz)

baz (a)
{
  int b;
  int T.0;

<bb 0>:
  T.0_1 = -080000000;
  b_3 = a_2 & T.0_1;
  if (b_3 != 0) goto <L0>; else goto <L1>;

<L0>:;
  bar () [tail call];

<L1>:;
  return;

}



;; Function baa (baa)

baa (a)
{
  int b;

<bb 0>:
  b_2 = a_1 & -2147483648;
  if (b_2 != 0) goto <L0>; else goto <L1>;

<L0>:;
  bar () [tail call];

<L1>:;
  return;

}

-- 
           Summary: [tree-ssa] Convert a sign bit testing into "a < 0"
           Product: gcc
           Version: 3.5.0
            Status: UNCONFIRMED
          Keywords: pessimizes-code
          Severity: enhancement
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: kazu at cs dot umass dot edu
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15457

[Bug tree-optimization/15457] [tree-ssa] Convert a sign bit testing into "a < 0"

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-05-15 12:06 -------
Confirmed.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2004-05-15 12:06:12
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15457

[Bug tree-optimization/15457] [tree-ssa] Convert a sign bit testing into "a < 0"

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
  BugsThisDependsOn|                            |15459


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15457

[Bug tree-optimization/15457] [tree-ssa] Convert a sign bit testing into "a < 0"

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-05-17 02:03 -------
PR 15359 will fix foo and baa but not baz for some reason.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15457

[Bug tree-optimization/15457] [tree-ssa] Convert a sign bit testing into "a < 0"

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-08 19:12 -------
(In reply to comment #2)
> PR 15359 will fix foo and baa but not baz for some reason.
I mean 15459.
Also this is done on the RTL level at least on PPC.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
OtherBugsDependingO|19987                       |
              nThis|                            |
           Keywords|                            |TREE


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15457

[Bug tree-optimization/15457] [tree-ssa] Convert a sign bit testing into "a < 0"

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-24 22:04 -------
All three are now done by PR 15459.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |pinskia at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15457

[Bug tree-optimization/15457] [tree-ssa] Convert a sign bit testing into "a < 0"

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=15457
Bug 15457 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/15457] [tree-ssa] Convert a sign bit testing into "a < 0"

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15457

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.3.0

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-01-05 23:12:07 UTC ---
Fixed since 4.3.0.

[Bug tree-optimization/15457] [tree-ssa] Convert a sign bit testing into "a < 0"

[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=15457