[Bug optimization/14814] New: Dead stores not eliminated

["dalej at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

The dead stores to the stack in foo are not eliminated until the RTL optimizers.
This is derived from the eon SPECmark, and similar constructs are common in C++.
13952 is related, but not the same.

class YY { public:
  YY(const YY &v) { e[0] = v.e[0]; e[1] = v.e[1]; e[2] = v.e[2]; }
  double &y() { return e[1]; }
  double e[3];  };

class XX { public:
  YY direction() const { return v; }
  YY v;  };

int foo(XX& r) {
  if (r.direction().y() < 0.000001) return 0;
  return 1; }

Here is a C variant (from Andrew Pinski) where the RTL optimizers aren't good enough:

struct YY {
  double e[3];  };

static inline double *y(struct YY* this_1) { return &this_1->e[1]; }

struct XX {
  struct YY v;
 };

static inline struct YY direction (const struct  XX* this_1) { return this_1->v;}

int foo(const struct XX* r) {
  struct YY t = direction(r);
  if (*y(&t) < 0.000001) return 0;
  return 1;
}

-- 
           Summary: Dead stores not eliminated
           Product: gcc
           Version: tree-ssa
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P2
         Component: optimization
        AssignedTo: dnovillo at gcc dot gnu dot org
        ReportedBy: dalej at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: powerpc-apple-darwin7.2.0
  GCC host triplet: powerpc-apple-darwin7.2.0
                    powerpc-apple-darwin7.2.0
GCC target triplet: powerpc-apple-darwin7.2.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14814