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Re: [avr-gcc-list] -O vs. -O2

From: Russell Shaw
Subject: Re: [avr-gcc-list] -O vs. -O2
Date: Fri, 27 Jul 2007 13:35:03 +1000
User-agent: Thunderbird (X11/20060501)

Nathan Cooprider wrote:
Russell Shaw wrote:
What are you trying to do? Any autoconf package can be set for -02 with:
./configure CFLAGS="-g -O2"

I am using avr-gcc as part of the TinyOS package, along with a bunch of other non-TinyOS tools. The non-TinyOS tools do something to the TinyOS applications so that they compile fine with avr-gcc -O, but then break with -Os or -O2. My understanding is that -O2 is just -O with some extra command options. I looked through the manual and found what options those were, but adding them to -O did not trigger the error. So I was at a loss.

Which manual did you look at?

Look under "Optimize Options" in "info gcc".

Unfortunately, I believe I am stuck using an older version of gcc. Which sort of makes my problem irrelevant for this list. Also, I probably just have to look at the actual command line options in the source and find out which ones -O turns on and which ones -O2 turns on. Anyway, thanks for the concern.

The individual options are listed under the section "Optimize Options"
in "info gcc".

More specifically, i'm currently looking at: File: gcc-4.0.info,
"3.10 Options That Control Optimization". Your gcc may have a different
section number.

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