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Subject: [Bug c/32575] [4.2/4.3 regression] With -ftree-vrp miscompiles a single line of code in SQLite
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------- Comment #6 from jakub at gcc dot gnu dot org  2007-08-28 15:58 -------
if (a == 0) a = bar (); isn't necessary either.

salias has:

  # BLOCK 2 freq:10000
  # PRED: ENTRY [100.0%]  (fallthru,exec)
  # VUSE <qD.2026_12(D), SMT.25D.2079_13(D)> { qD.2026 SMT.25D.2079 }
  D.2027_3 = foo ();
  pD.2025_4 = (struct S *) D.2027_3;
  if (pD.2025_4 == 0B)
    goto <bb 3>;
  else
    goto <bb 4>;
  # SUCC: 3 [7.3%]  (true,exec) 4 [92.7%]  (false,exec)

  # BLOCK 3 freq:735
  # PRED: 2 [7.3%]  (true,exec)
  # qD.2026_15 = VDEF <qD.2026_12(D)>
  # SMT.25D.2079_16 = VDEF <SMT.25D.2079_13(D)>
  # SMT.26D.2080_17 = VDEF <SMT.26D.2080_14(D)> { qD.2026 SMT.25D.2079
SMT.26D.2080 }
  __builtin_memset (&qD.2026, 0, 24);
  # SUCC: 4 [100.0%]  (fallthru,exec)

  # BLOCK 4 freq:10000
  # PRED: 2 [92.7%]  (false,exec) 3 [100.0%]  (fallthru,exec)
  # qD.2026_11 = PHI <qD.2026_12(D)(2), qD.2026_15(3)>
  # pD.2025_1 = PHI <pD.2025_4(2), &qD.2026(3)>
  # qD.2026_18 = VDEF <qD.2026_11> { qD.2026 }
  pD.2025_1->s1D.2008 = aD.2021_6(D);
  # qD.2026_19 = VDEF <qD.2026_18> { qD.2026 }
  pD.2025_1->s2D.2009 = bD.2022_7(D);

Shouldn't the VDEFs be a PHI of some SMT and qD?  pD.2025_1 can either be what
foo returned, or it can point to the automatic variable q.


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.2.2                       |---


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32575