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Re: GCC -On optimization passes: flag and doc issues
As Steven Bosscher wrote:
> Maybe you can look at the development of code size of AVR over time,
> and show a different trend, but I'd be surprised.
Most AVR users use -Os, as small code is fast code in most of the
cases on the AVR. The `overall summary' is that GCC continuously
decreased its efficiency in code generation throughout the 3.x version
line. It's never been a dramatic change, but with each compiler
version, the code grew by a percent or two. Sure, bugs have been
fixed than, and obviously, the older (smaller) code had a higher
probability of being incorrect. However, the perception of the users
(and don't underestimate their perception!) was that GCC actually got
worse over time.
With GCC 4.x (where x >= 1 so the initial regressions had already been
sorted out), there's now a completely different picture. There are
people who easily gained 5...10 % code size in large projects, but
there are as well numerous cases where the resulting code size
increased by a similar dramatical value when switching from GCC 3.x to
4.x. As it turns out, most (if not all) of the latter are due to the
automatic inlining that is now enabled with -Os.
This is why that ``silly'' bug report has been filed: it *is* annoying
a good number of (AVR-)GCC users, and it *is* a regression, compared
to GCC 3.x.
--
cheers, J"org .-.-. --... ...-- -.. . DL8DTL
http://www.sax.de/~joerg/ NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)