Re: Why not build kernel with -O3

From: Austin S Hemmelgarn
Date: Wed Apr 08 2015 - 09:53:55 EST


On 2015-04-08 09:19, Pengfei Yuan wrote:
2015-04-08 20:06 GMT+08:00 Austin S Hemmelgarn <ahferroin7@xxxxxxxxx>:
I can't remember any off the top of my head, but it does say explicitly in
the GCC manual to be careful with -O3. IIRC, most of the issues relate to
-O3 enabling -ffast-math (which tends to really mess with code that expects
strict IEEE 754 compliance), so it may not be as much of an issue for kernel
code. You might look into some of the projects that use -O3 by default (I
think most of the Mozilla so0ftware does these days, and I know that there
are others, I just can't remember what right now).


I am afraid you are talking about -Ofast, not -O3.
See https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html

Yuan

You're right, I had been looking at the wrong paragraph in the info manual. Sorry about any confusion.

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