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Re: [avr-gcc-list] Gcc branches small comparison.


From: Dmitry K.
Subject: Re: [avr-gcc-list] Gcc branches small comparison.
Date: Mon, 24 Jan 2005 17:22:39 +1000
User-agent: KMail/1.5

On Sunday 23 January 2005 16:44, Dmitry K. wrote:
[...]
>                 3.2.3   3.3.5   3.4.3   4.0     4.0-nrr
>
> do_random       102+14   91+10   93+10  173+14  173+14

The reason is:
avr-gcc 4.0 (20050116) replaces multiplication by a constant to a combination 
of more simple operations. Thus it does not pay attention to efficiency of 
such replacement.  

For example: 
        int foo (int x) { return 24011 * x; } 
produce 49 words (-mmcu=atmega8 -Os). 
Older GCC branches -- only 11 words in this case.

I have send the bug to gcc-buglist (#19597).



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