RE: [avr-gcc-list] Odd prologue for ATmega256x in WinAVR20080407

[Stu Bell]

My thanks to all involved!  Very clever!

Only reason I asked was I was comparing code between 20071221 and
20080407 (still trying to get my code running on the latest gcc) and
came across it. 

Best regards, 

Stu Bell 
DataPlay (DPHI, Inc.) 


-----Original Message-----
From: address@hidden [mailto:address@hidden 
Sent: Thursday, April 10, 2008 12:53 PM
To: address@hidden; address@hidden; address@hidden;
Stu Bell
Subject: Re: [avr-gcc-list] Odd prologue for ATmega256x in
WinAVR20080407

Hey ! I wrote RTL prolog code.



-----Original Message-----
From: Weddington, Eric <address@hidden>
To: Jeff Barlow <address@hidden>; address@hidden; Stu Bell
<address@hidden>
Sent: Thu, 10 Apr 2008 2:42 pm
Subject: RE: [avr-gcc-list] Odd prologue for ATmega256x in
WinAVR20080407





> -----Original Message-----
> From:
> address@hidden
> [mailto:address@hidden
> org] On Behalf Of Jeff Barlow
> Sent: Thursday, April 10, 2008 9:10 AM
> To: address@hidden
> Subject: Re: [avr-gcc-list] Odd prologue for ATmega256x in
> WinAVR20080407
>
> Stu Bell <address@hidden>  wrote:
>
> >What does the double "rcall ." do?
>
> It just adjusts the stack pointer prior to loading it as the local 
> frame pointer. It's a fairly cute optimization actually.
>

Hi Stu,

Don't feel bad. When I first saw this, I thought the same thing: "Huh?,
What's this?" After some quick double checking in the instruction set
manual, it finally made sense. I agree with Jeff, it's quite a trick
optimization. Thanks go to Anatoly Sokolov. ;-)


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