Quoting Andi Kleen <a...@firstfloor.org>:
if (__builtin_constant_p(x) && x == 1) ... and assume the compiler can collapse at compile time then a SYMBOL_REF wouldn't DTRT.
Unless you set x to the address of a variable / function and this is constant-propagated, x will not become a SYMBOL_REF. If x is a variable with static storage, it will be a MEM (symbol_ref). &x will be a SYMBOL_REF.
