Bug ID: 77698
           Summary: Loop not considered hot after profiling
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: gcov-profile
          Assignee: unassigned at gcc dot
          Reporter: pthaugen at gcc dot
                CC: dje at gcc dot, hubicka at gcc dot,
                    wschmidt at gcc dot
  Target Milestone: ---
              Host: powerpc64*-unknown-linux-gnu
            Target: powerpc64*-unknown-linux-gnu
             Build: powerpc64*-unknown-linux-gnu

// gcc -O3 -o run -fno-tree-vectorize -funroll-loops --param max-unroll-times=4
-fno-inline run.c
// -fprofile-generate/-fprofile-use
volatile long int j = 0;

void foo(long int *a, long int *b, long int n)
  long int i;

  for (i = 0; i < n; i++)
    a[j] = *b;

long int a, b;
int main()
  a = 1; b = 2;
  foo(&a, &b, 1000000);
  return (a+b);

When I built the above testcase with profile info and unrolling I noticed the
loop was not getting aligned. The label is getting skipped in
final.c:compute_alignments() because optimize_bb_for_size_p() is returning
true. I poked a little further and saw that predict.c:maybe_hot_count_p() is
returning false here:

  return (count >= get_hot_bb_threshold ());

because 'count'=250000 and get_hot_bb_threshold() returns 1000000. The bb count
is correct for unrolling the loop by 4. The value returned by
get_hot_bb_threshold() seems incorrect, shouldn't need to be the max count to
be considered hot (with unrolling it will never have that value).

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