Sender: jur AT rz DOT hu-berlin DOT de
Message-ID: <378DD81A.D4B1586D@informatik.hu-berlin.de>
Date: Thu, 15 Jul 1999 12:46:18 +0000
From: Jens-Uwe Rumstich <rumstich AT informatik DOT hu-berlin DOT de>
Organization: TUSCON
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To: pgcc AT delorie DOT com
Subject: Re: calling functions
References: <3 DOT 0 DOT 32 DOT 19990715013633 DOT 010d9ab0 AT pop DOT xs4all DOT nl> <14221 DOT 16161 DOT 37716 DOT 619890 AT lrz DOT de>
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Reply-To: pgcc AT delorie DOT com

Eugene Leitl wrote:
> 
> Vincent Diepeveen writes:
>  > Good morning,
>  >
>  > Reading through the ia-64 technical manual the merced
>  > seems to have many registers:
Hi!
 
> The downside of having many registers is of course the need to save a
> lot of state when the need to switch context arises.

If I understood the IA64 material right, you have to tell the CPU, how
much registers are needed by the function and which (from the outer
routines) it wants to have access to. These number of registers is
reserved for this function and only them can be accessed and only them
have to be saved during a context switch. If there are not enough
registers free, some blocked registers will be spilled somewhere until
the needed number of registers is available.

cu
	Jens-Uwe