[Bug tree-optimization/39761] New: ccp does not fully propagate constant real/imaginary parts

[bonzini at gnu dot org]

>From this testcase:

void bar();
void foo(int i)
{
  __complex__ int k = 0;
  if (i)
    k = 1;
  if (k)
    bar();
}

(cfr. gcc.c-torture/compile/pr35431.c) we get after cddce1:

  # k_1 = PHI <__complex__ (0, 0)(2), __complex__ (1, 0)(3)>
  D.1198_6 = REALPART_EXPR <k_1>;
  if (D.1198_6 != 0)
    goto <bb 6>;
  else
    goto <bb 5>;

<bb 5>:
  D.1200_7 = IMAGPART_EXPR <k_1>;
  if (D.1200_7 != 0)
    goto <bb 6>;
  else
    goto <bb 7>;

and the IMAGPART_EXPR could be CCP'd or FRE'd to zero.  Likewise the
REALPART_EXPR could be FRE'd to PHI <0(2), 1(3)>.


-- 
           Summary: ccp does not fully propagate constant real/imaginary
                    parts
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: bonzini at gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39761