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* [Bug tree-optimization/99739] New: [11 Regression] missing optimization of a repeated conditional
@ 2021-03-23 20:56 msebor at gcc dot gnu.org
  2021-03-24  9:13 ` [Bug tree-optimization/99739] " rguenth at gcc dot gnu.org
                   ` (7 more replies)
  0 siblings, 8 replies; 9+ messages in thread
From: msebor at gcc dot gnu.org @ 2021-03-23 20:56 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99739

            Bug ID: 99739
           Summary: [11 Regression] missing optimization of a repeated
                    conditional
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: msebor at gcc dot gnu.org
  Target Milestone: ---

Prior to r11-5805 both ff() and gg() in the test case below resulted in optimal
code.  With the change, the second conditional in g() is no longer recognized
as equivalent to the first and so the function isn't optimized as expected.

Incidentally, the same regression was also introduced once before: in r235653.

$ cat x.c && gcc -O1 -S -Wall -fdump-tree-optimized=/dev/stdout x.c
static inline int f (int i, int j, int k)
{
  int x = 1;

  if (i && j && k)
    x = 2;

  if (i && j && k)
    return x;

  return -1;
}

void ff (int i, int j, int k)
{
  int x = f (i, j, k);
  if (x == 1)
    __builtin_abort ();
}


static inline int g (int i, int j, int k)
{
  int x = 1;

  if (i && j && k)
    x = 2;

  if (i && k && j)
    return x;

  return -1;
}

void gg (int i, int j, int k)
{
  int x = g (i, j, k);
  if (x == 1)
    __builtin_abort ();
}

;; Function ff (ff, funcdef_no=1, decl_uid=1951, cgraph_uid=2, symbol_order=1)

void ff (int i, int j, int k)
{
  <bb 2> [local count: 1073741824]:
  return;

}



;; Function gg (gg, funcdef_no=3, decl_uid=1963, cgraph_uid=4, symbol_order=3)

Removing basic block 6
Removing basic block 7
void gg (int i, int j, int k)
{
  _Bool _7;
  _Bool _8;
  _Bool _11;
  _Bool _14;
  _Bool _16;

  <bb 2> [local count: 1073741824]:
  _7 = i_2(D) != 0;
  _8 = j_3(D) != 0;
  _14 = k_4(D) != 0;
  _11 = _7 & _14;
  _16 = _8 & _11;
  if (_16 != 0)
    goto <bb 3>; [94.27%]
  else
    goto <bb 5>; [5.73%]

  <bb 3> [local count: 1012175616]:
  if (k_4(D) != 0)
    goto <bb 5>; [100.00%]
  else
    goto <bb 4>; [0.00%]

  <bb 4> [count: 0]:
  __builtin_abort ();

  <bb 5> [local count: 1073741824]:
  return;

}

^ permalink raw reply	[flat|nested] 9+ messages in thread
end of thread, other threads:[~2023-05-29 10:04 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-03-23 20:56 [Bug tree-optimization/99739] New: [11 Regression] missing optimization of a repeated conditional msebor at gcc dot gnu.org
2021-03-24  9:13 ` [Bug tree-optimization/99739] " rguenth at gcc dot gnu.org
2021-04-27 11:40 ` [Bug tree-optimization/99739] [11/12 " jakub at gcc dot gnu.org
2021-07-28  7:06 ` rguenth at gcc dot gnu.org
2022-04-21  7:49 ` rguenth at gcc dot gnu.org
2023-03-23 17:57 ` pinskia at gcc dot gnu.org
2023-03-23 18:03 ` jakub at gcc dot gnu.org
2023-03-24  8:41 ` cvs-commit at gcc dot gnu.org
2023-05-29 10:04 ` jakub at gcc dot gnu.org

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