This is the mail archive of the
mailing list for the GCC project.
Re: Overwhelmed by GCC frustration
On Wed, Aug 2, 2017 at 3:54 PM, Segher Boessenkool
> On Tue, Aug 01, 2017 at 01:50:14PM +0200, David Brown wrote:
>> I would not expect that to be good at all. With no optimisation (-O0),
>> gcc produces quite poor code - local variables are not put in registers
>> or "optimised away", there is no strength reduction, etc. For an
>> architecture like the AVR with a fair number of registers (32, albeit
>> 8-bit registers) and relatively inefficient stack access, -O0 produces
>> /terrible/ code.
> -Og is better though (better than any other -O for this test at least).
> The regression happened before 4.7, it seems the big jump was with 4.6?
> So what happened there? This seems to happen on x86 as well, maybe
> on everything.
And one function (of the two) shrinks compared to 3.4 and the other increases
so the jumps are probably mis-bisected anyway.