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Re: Skipping assembler when producing slim LTO files


On Wed, Sep 24, 2014 at 10:04 AM, Steven Bosscher <stevenb.gcc@gmail.com> wrote:
> On Wed, Sep 24, 2014 at 6:32 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
>> Libreoffice shows that GCC needs about twice as much of system time. According
>> to profiles, good part is the ugly way we pass stuff down to assembler and
>> other part is memory use during the copmilation stage.
>
> Are you using -pipe? AFAIR this still isn't the default, even on
> GNU/Linux, but it is typically a lot faster than without.

Is that true even when TMPDIR is on a ram disk?  There's no obvious
reason that it should be true in a parallel build.  Using -pipe
effectively constrains communication between the compiler and the
assembler to work in PIPE_BUF blocks.  Using TMPDIR introduces no such
constraints, and in a big program a parallel build should obscure the
fact that the compiler and assembler are serialized for each
individual compilation unit.

Ian


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