[Bug c/66090] Wrong loop code generation with -O2 on ARM

[kugan at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66090

kugan at gcc dot gnu.org changed:

           What    |Removed                     |Added
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                 CC|                            |kugan at gcc dot gnu.org

--- Comment #1 from kugan at gcc dot gnu.org ---
trunk also has the same issue and ivopt seems to be wrong here:

in test.c.135t.cunroll:

  # ivtmp_2 = PHI <ivtmp_1(4), 1024(2)>
  ptr_5 = ptr_12 + 4;
  *ptr_12 = 0;
  i_7 = i_11 + 1;
  ivtmp_1 = ivtmp_2 - 1;
  if (ivtmp_1 != 0)


In test.c.138t.ivopts:

  # ptr_12 = PHI <ptr_5(4), 4294963200B(2)>
  ptr_5 = ptr_12 + 4;
  MEM[base: ptr_5, offset: 4294967292B] = 0;
  if (ptr_5 != 0B)

In vrp, ptr_5 is ~[0B, 0B] and hence the condition is eliminated but the
problem was introduced in ivopt.