RFD: Should __builtin_constant_p approximate CONSTANT_P ?

[Andi Kleen]

Joern Rennecke <joern.rennecke@embecosm.com> writes:
>
> More importantly. addresses that becomes a SYMBOL_REF should be considered
> constant.  I.e. In particular, the addresses of variables with static storage.
> I have a simple patch to recognize these as constants;
> do people agree that this is the right thing to do?

if someone writes

if (__builtin_constant_p(x) && x == 1) ... and assume the compiler can
collapse at compile time then a SYMBOL_REF wouldn't DTRT.
I've seen quite a bit such code. So I would prefer to accept only numbers known
at compile time already.

-Andi


-- 
ak@linux.intel.com -- Speaking for myself only