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Re: 32bit Calling conventions on linux/ppc.
- From: David Edelsohn <dje at watson dot ibm dot com>
- To: Joslwah <joslwah at gmail dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: Fri, 24 Nov 2006 22:59:20 -0500
- Subject: Re: 32bit Calling conventions on linux/ppc.
- References: <20061116173208.cb8cdac3.joslwah@gmail.com>
>>>>> Joslwah writes:
Joslwah> Looking at the Linux 32bit PowerPC ABI spec, it appears to me that
Joslwah> floats in excess of those that are passed in registers are supposed to
Joslwah> be promoted to doubles and passed on the stack. Examing the resulting
Joslwah> stack from a gcc generated C call it appears they are passed as
Joslwah> floats.
Joslwah> Can someone confirm/refute this, or else point me to an ABI that says
Joslwah> that they should be passed as floats.
The SVR4 PowerPC ABI Supplement does seem to imply that floats
should be passed in the stack as doubles. The PowerPC Linux ABI is not
identical to the SVR4 PPC ABI. I am not sure what benefit might be gained
by promoting floats passed on the stack to double.
David