AW: howto use -fstack-check

["Scholz Maik (CM-CR/EES3) *" <Maik.Scholz@de.bosch.com>]

small example:
foo.c:
	void foo2()
	{
	}

	void foo1()
	{
	  int i;
	  i = 1;
	  foo2();
	}

miplsisa32-elf -S -fstack-check
foo.s:
	.file	1 "foo.c"
	.section	.text
gcc2_compiled.:
__gnu_compiled_c:
	.text
	.align	2
	.globl	foo2
	.ent	foo2
foo2:
	.frame	$fp,16,$31		# vars= 0, regs= 1/0, args= 0,
extra= 0
	.mask	0x40000000,-16
	.fmask	0x00000000,0
	subu	$sp,$sp,16
	sw	$fp,0($sp)
	move	$fp,$sp
	move	$sp,$fp
	lw	$fp,0($sp)
	addu	$sp,$sp,16
	j	$31
	.end	foo2
	.align	2
	.globl	foo1
	.ent	foo1
foo1:
	.frame	$fp,32,$31		# vars= 16, regs= 2/0, args= 0,
extra= 0
	.mask	0xc0000000,-12
	.fmask	0x00000000,0
	subu	$sp,$sp,32
	sw	$31,20($sp)
	sw	$fp,16($sp)
	move	$fp,$sp
added code	|	addu	$2,$sp,-4392
added code	|	#.set	volatile
added code	|	sw	$0,0($2)
added code	|	#.set	novolatile
	li	$2,1			# 0x1
	sw	$2,0($fp)
	jal	foo2
	move	$sp,$fp
	lw	$31,20($sp)
	lw	$fp,16($sp)
	addu	$sp,$sp,32
	j	$31
	.end	foo1

Is there any description how to use the 
"extra generated code".

Regards

Maik

-----Ursprüngliche Nachricht-----
Von: Manfred Hollstein [mailto:manfredh@redhat.com]
Gesendet: Mittwoch, 24. April 2002 13:49
An: Scholz Maik (CM-CR/EES3) *
Cc: 'gcc@gcc.gnu.org'
Betreff: Re: howto use -fstack-check


Scholz Maik (CM-CR/EES3) * wrote:
> We have an embedded system with a
> RTOS without any stack check.
> 
> How can I use the gcc build in stack check
> "-fstack-check"

 From gcc's info page:

`-fstack-check'
      Generate code to verify that you do not go beyond the boundary of
      the stack.  You should specify this flag if you are running in an
      environment with multiple threads, but only rarely need to specify
      it in a single-threaded environment since stack overflow is
      automatically detected on nearly all systems if there is only one
      stack.

      Note that this switch does not actually cause checking to be done;
      the operating system must do that.  The switch causes generation
      of code to ensure that the operating system sees the stack being
      extended.

This means to me, you try with "-S -fstack-check" when compiling
your code and see how the generated code looks like.

> 
> Regards
> 
> Maik Scholz
> 

HTH.

Cheers.

l8er
manfred

-- 
Manfred Hollstein                         <mailto:manfredh@redhat.com>
Red Hat GmbH
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