[Bug tree-optimization/26258] New: [4.1 Regression] Wrong alias information for SRAed struct copy

[rguenth at gcc dot gnu dot org]

Compiling with -O2 the following creates invalid virtual operands after
SRA:

struct Foo { int a; int b; };

Foo foo(Foo p, bool ret_first)
{
  Foo first = p;
  Foo last = p;
  return ret_first ? first : last;
}

  # iftmp.0D.1761_1 = PHI <&firstD.1740(1), &lastD.1757(0)>;
<L2>:;
  #   VUSE <SFT.6D.1783_24>;
  #   VUSE <SFT.8D.1785_26>;
  SR.26D.1803_27 = iftmp.0D.1761_1->bD.1735;
  #   VUSE <SFT.6D.1783_24>;
  #   VUSE <SFT.8D.1785_26>;
  SR.25D.1802_28 = iftmp.0D.1761_1->aD.1734;

the access to ->b should VUSE SFTs 5 and 7.


-- 
           Summary: [4.1 Regression] Wrong alias information for SRAed
                    struct copy
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Keywords: wrong-code, alias
          Severity: normal
          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=26258