[Mesa-dev] [PATCH] mesa: Enable LTO compilation

[Rob Clark]

On Mon, May 30, 2016 at 1:39 PM, Matt Turner <mattst88 at gmail.com> wrote:
> On Mon, May 30, 2016 at 10:28 AM, ⚛ <0xe2.0x9a.0x9b at gmail.com> wrote:
>> This patch enables compilation with -flto.
>>
>> The performance benefits of LTO (GCC 4.9 & 6.1) are about 1% for glxgears.
>> Performance changes in OpenGL games haven't been measured yet, my feeling is
>> that they are negligible.
>
> Without a compelling reason, I don't think the build system should be
> adding compiler flags like this.
>
> -flto makes debugging impossible, at least the last time I tried it
> with gcc. I don't think that's something we would want enabled
> whenever it's supported.

It would be interesting to know what gains it brings in scenarios less
synthetic than glxgears..  my suspicion is that we have been doing
manual lto forever (ie. use of static-inline fxn's where it matters).
If it turns out to be a significant gain, I wouldn't be against it.
Although perhaps only for non-debug builds..

BR,
-R

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