On 11/06/13 08:27, Jakub Jelinek wrote:
On Wed, Nov 06, 2013 at 04:23:06PM +0100, Richard Biener wrote:
In that case I think it would be fine to run the isolate paths
optimization, but to not omit the actual dereference of the NULL
pointer (possibly the dereference could be followed by a trap).
Yeah, we need the trap to properly end the BB (even if that is a
waste instruction generated).
BTW, why do we generate in this optimization __builtin_trap rather than
just __builtin_unreachable ()? The former still generates some code (abort,
some aborting instruction, ...), while the former is just an assertion that
valid code will not reach it.
Because if you do reach the site, you really want to halt the program to
avoid potential security exploits. I'm actually of the opinion that
builtin_unreachable should be trapping as well.
jeff
