Re: [PATCH GIT 0.6] make use of register variables & size_t

From: Linus Torvalds
Date: Mon Apr 25 2005 - 13:50:11 EST

On Mon, 25 Apr 2005, Matthias-Christian Ott wrote:
> But this makes, like "register", direct use of processor registers (it
> stores int arguments in eax, ebx, etc.).

No. It make _unlike_ "register", direct use of processor registers.

The "register" keyword does _not_ use processor registers. It's just
syntactic fluff, and tells the compiler exactly one thing:

- that the compiler should warn if you take the address of such a thing.

In addition, the compiler may generate code that takes it into account,
which most likely means _worse_ code than if it didn't take it into

In contrast regparm() actually says something very relevant: it says that
the function uses a totally different calling convention.

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