Question about AMD64 ABI

Reply: Paul Procacci : "Re: Question about AMD64 ABI"
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From: Daniel Cervus <DanieltheDeer_at_outlook.com>
Date: Sun, 13 Nov 2022 03:30:46 UTC

Hi everyone,

I’m trying to do assembly programming on FB in 64-bit mode. I have a question, 64-bit mode requires parameters to be passed on 64-bit registers. But when a parameter is 32-bit or smaller, do I need to sign-extend (or zero-extend) them to 64-bit? The System V ABI specifications only says "The size of each argument gets rounded up to eightbytes." It’s somewhat ambiguous. How to round up 'float', when they are passed on stack?

Thanks,
Daniel