Help with RTL expand and a builtins

[Martin Liška]

On 07/18/2017 04:49 PM, Segher Boessenkool wrote:
> On Tue, Jul 18, 2017 at 12:49:06PM +0200, Martin Liška wrote:
>> Solved, tail call was responsible for dead RTL instructions.
> 
> This seems similar to https://gcc.gnu.org/ml/gcc-patches/2017-07/msg00362.html
> then.  Is it?
> 
> There are many cases where we generated dead code during expand on
> purpose (some just laziness, some to avoid code complications).
> Because of this it is hard to detect where we generate dead code that
> is just plain wrong (should not be dead).  And such things aren't
> trivial to debug :-(

Yep, exactly. It was really hard to debug! I tried many different approaches how to
generate sequence of RTL instructions and nothing :) Maybe writing to a dump_file
that RTL insns are eliminated will be handy?

Martin

> 
> 
> Segher
>