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Re: Passing args in stack or register for each function
- From: Michael Meissner <meissner at linux dot vnet dot ibm dot com>
- To: Le Ton Chanh <letonchanh at yahoo dot com>
- Cc: GCC Help <gcc-help at gcc dot gnu dot org>
- Date: Wed, 12 Nov 2008 12:16:15 -0500
- Subject: Re: Passing args in stack or register for each function
- References: <133237.63085.qm@web38107.mail.mud.yahoo.com>
On Tue, Nov 11, 2008 at 04:32:21PM -0800, Le Ton Chanh wrote:
> I want to design a backend on GCC which has following feature: The functions
> which have the attribute "pass_in_reg" (the attribute I defined) will pass
> their arguments in registers; otherwise, they will pass arguments in stack.
> Now I can do that, but the callee functions don't know the position of
> arguments passing from caller exactly, it's wrong. Does GCC support to do
> that? Can anyone help me? Thanks in advance.
>
> Le Ton Chanh
> email:letonchanh at yahoo dot com
Several ports support this already. For example, the i386 port provides
"regparm" where you can say how many arguments are passed in registers. If you
have alternate calling sequences, your users should have the appropriate
prototypes for the function before any calls, references, or the definition.
You have to define the appropriate stuff in the back end function handling
stuff (FUNCTION_ARG_...) to make sure the caller and callee are consistant.
--
Michael Meissner, IBM
4 Technology Place Drive, MS 2203A, Westford, MA, 01886, USA
meissner@linux.vnet.ibm.com