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Re: [avr-gcc-list] optimizer removes volatile pin access code. why?
From: |
Joerg Wunsch |
Subject: |
Re: [avr-gcc-list] optimizer removes volatile pin access code. why? |
Date: |
Tue, 27 Oct 2009 20:17:46 +0100 (MET) |
Joerg Desch <address@hidden> wrote:
> With -Os enables, the setup of the port pin is removed! Without
> optimization the pin toggles as expected.
How did you verify it?
I don't believe the compiler removed the code. (If you really think
it does, please supply a compilable code example.) However, the
optimized code will just toggle the pin for a single CPU cycles only,
while the pin will stay a little longer at high in the non-optimized
example. So if your oscilloscope is too slow, you might not notice
the pin actually becoming high for one clock period.
--
cheers, J"org .-.-. --... ...-- -.. . DL8DTL
http://www.sax.de/~joerg/ NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)
- [avr-gcc-list] optimizer removes volatile pin access code. why?, Joerg Desch, 2009/10/27
- Re: [avr-gcc-list] optimizer removes volatile pin access code. why?,
Joerg Wunsch <=
- [avr-gcc-list] Re: optimizer removes volatile pin access code. why?, Joerg Desch, 2009/10/28
- [avr-gcc-list] Re: optimizer removes volatile pin access code. why?, David Brown, 2009/10/28
- [avr-gcc-list] Re: optimizer removes volatile pin access code. why?, Joerg Desch, 2009/10/28
- Re: [avr-gcc-list] Re: optimizer removes volatile pin access code. why?, Erik Christiansen, 2009/10/28
- [avr-gcc-list] Re: optimizer removes volatile pin access code. why?, Joerg Desch, 2009/10/31
- [avr-gcc-list] Re: optimizer removes volatile pin access code. why?, Erik Christiansen, 2009/10/28
- [avr-gcc-list] Re: optimizer removes volatile pin access code. why?, David Brown, 2009/10/28
- RE: [avr-gcc-list] Re: optimizer removes volatile pin access code. why?, Stu Bell, 2009/10/28
- [avr-gcc-list] Re: optimizer removes volatile pin access code. why?, David Brown, 2009/10/29
- RE: [avr-gcc-list] Re: optimizer removes volatile pin access code. why?, Stu Bell, 2009/10/30