[Bug tree-optimization/41490] New: tree-ssa-sink does not really work

[rguenth at gcc dot gnu dot org]

It can't sink stores at all due to some defects.  For

int foo(int *a, int r)
{
  int ret = 0;
  *a = 1;
  if (r == 3)
    *a = 5;
  else
    ret = r + 20;
  return ret;
}

the store to *a should be sunk into the else block.

Likewise for

int foo(int *a, int r, short *b)
{
  int ret = 0;
  *a = 1;
  if (r == 3)
    *a = 5;
  else
    ret = r + 20;
  *b = 9;
  return ret;
}

for

int foo(int *a, int r, short *b)
{
  int ret = 0;
  *a = 1;
  switch (r)
  {
  case 3:
    *a = 5;
    break;
  case 4:
  case 5:
    *a = 9;
    ret = r + 25;
    break;
  default:
    ret = r + 20;
  }
  *b = 9;
  return ret;
}

it should go into the default case.

I have a patch, but that requires the function exit to use .MEM.


-- 
           Summary: tree-ssa-sink does not really work
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rguenth at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41490