[Bug middle-end/35303] New: Code hoisting optimization at tree level

[xinliangli at gmail dot com]

Missing code size optimization at tree level -- which is more flexible than RTL
level (allow hoisting memory operations).

int g1,g2;
int foo(int a, int b)
{
    if (a)
       g1 = a + b;
    else if (b)
       g2 = a+ b;
    else 
       g3 = a + b
    return g1 + g2;
}

With hoisting, it should be transformed into:

int g1, g2, g3;
int foo(int a, int b)
{
    t = a+b;
    if (a)
       g1 = t;
    else if (b)
       g2 = t;
    else 
       g3 = t;
    return g1 + g2;
}


-- 
           Summary: Code hoisting optimization at tree level
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: xinliangli at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35303