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Re: [avr-gcc-list] Weird optimization issue with avr-gcc 4.5.3, re "nake
From: |
Georg-Johann Lay |
Subject: |
Re: [avr-gcc-list] Weird optimization issue with avr-gcc 4.5.3, re "naked." |
Date: |
Fri, 27 Jan 2012 12:23:40 +0100 |
User-agent: |
Thunderbird 2.0.0.24 (X11/20100302) |
William "Chops" Westfield wrote:
> On Jan 26, 2012, at 2:10 PM, Georg-Johann Lay wrote:
>
>> I tested the code with avr-gcc 4.5 and command line options -Os -mmcu=atmega8
>>
>> With the attributes, the object size is 54 bytes.
>> Without the attributes the object size is 64 bytes.
>
> 4.5.3 ? Whatever this issue is, it apparently snuck in between 4.5.2 and
> 4.5.3.
The only remarkable difference between 4.5.2 and 4.5.3 is the fix of PR42240.
Depending on what distribution you use, your distributor added more patches, so
we don't know.
> and more substantial diffs, including the following.
> "naked" deletes the prolog, but adds instructions in the body...
> -.LM7:
> +.LSM6:
> ldi r24,lo8(5)
> - rjmp .L8
> + rcall putch
> + rjmp .L4
> .L3:
> -.LM8:
> +.LSM7:
> cpi r24,lo8(-127)
> brne .L5
> -.LM9:
> +.LSM8:
> ldi r24,lo8(4)
> - rjmp .L8
> + rcall putch
> + rjmp .L4
> .L5:
> -.LM10:
> +.LSM9:
> ldi r24,lo8(3)
>
Some of the diff noise is because of different debug symbols/labels; Hunans see
more without -g because of reduces debug info noise.
The other changes look reasonable with fix PR42240.
You may also want to have a look at OS_task and OS_main function attributes.
If an older toolchain works better for you, maybe you are fine with the older
version.
Johann
- Re: [avr-gcc-list] Weird optimization issue with avr-gcc 4.5.3, re "naked.", (continued)
- Re: [avr-gcc-list] Weird optimization issue with avr-gcc 4.5.3, re "naked.", Bill Westfield, 2012/01/27
- Re: [avr-gcc-list] Weird optimization issue with avr-gcc 4.5.3, re "naked.", Bill Westfield, 2012/01/27
- Re: [avr-gcc-list] Weird optimization issue with avr-gcc 4.5.3, re "naked.", Jan Waclawek, 2012/01/27
- Re: [avr-gcc-list] Weird optimization issue with avr-gcc 4.5.3, re "naked.", Georg-Johann Lay, 2012/01/27
- Re: [avr-gcc-list] Weird optimization issue with avr-gcc 4.5.3, re "naked.", William \"Chops\" Westfield, 2012/01/28
- Re: [avr-gcc-list] Weird optimization issue with avr-gcc 4.5.3, re "naked.", William \"Chops\" Westfield, 2012/01/28
- Re: [avr-gcc-list] Weird optimization issue with avr-gcc 4.5.3, re "naked.", Volker Kuhlmann, 2012/01/28
- Re: [avr-gcc-list] Weird optimization issue with avr-gcc 4.5.3, re "naked.", Georg-Johann Lay, 2012/01/28
Re: [avr-gcc-list] Weird optimization issue with avr-gcc 4.5.3, re "naked.", Georg-Johann Lay, 2012/01/26
Message not availableRe: [avr-gcc-list] Weird optimization issue with avr-gcc 4.5.3, re "naked.", Bill Westfield, 2012/01/27
Re: [avr-gcc-list] Weird optimization issue with avr-gcc 4.5.3, re "naked.", Weddington, Eric, 2012/01/27
Re: [avr-gcc-list] Weird optimization issue with avr-gcc 4.5.3, re "naked.", Georg-Johann Lay, 2012/01/30
Re: [avr-gcc-list] Weird optimization issue with avr-gcc 4.5.3, re "naked.", Weddington, Eric, 2012/01/30
Re: [avr-gcc-list] Weird optimization issue with avr-gcc 4.5.3, re "naked.", Johannes Bauer, 2012/01/27
Re: [avr-gcc-list] Weird optimization issue with avr-gcc 4.5.3, re "naked.", Joerg Wunsch, 2012/01/27