From mboxrd@z Thu Jan  1 00:00:00 1970
From: Nick Clifton <nickc@cygnus.com>
To: vlebedev@aplio.fr
Cc: gcc@gcc.gnu.org
Subject: Re: code generation for arm targets
Date: Wed, 22 Mar 2000 10:11:00 -0000
Message-id: <200003221810.KAA13226@elmo.cygnus.com>
X-SW-Source: 2000-03/msg00570.html

Hi Vadim,

: I see some strange things in code generation for arm-elf target:
:
:     28		str	lr, [sp, #-4]!
: 
: Take a look at line 28.
: 
: The lr register is saved in the "unallocated" stack area. The stack
: pointer is updated to include local variables frame only  at line
: 33. 

No its not.

: Wouldn't it be safer (with respect to interrupt and signal handling)
: to update the stack pointer immiedately upon entering the function? 

You missed the ! at the end of the instruction.  This indicates a
pre-indexed addressing mode.  In this case the instruction will
compute:

	sp  = sp - 4
	*sp = lr

so that stack pointer is updated before (or at the same time as) the
stack slot is written to.

Cheers
	Nick