Re: [PATCH] Remove some divide instructions

[Linus Torvalds]

On Wed, 27 Oct 2004, Linus Torvalds wrote:
> 
> I could add a sparse check for "no side effects", if anybody cares (so 
> that you could do
> 
> 	__builtin_warning(
> 		!__builtin_nosideeffects(base),
> 		"expression has side effects");
> 
> in macros like these.. Sparse already has the logic internally..

Done. Except I called it __builtin_safe_p(). 

The kernel sources already know about "__builtin_warning()" (and 
pre-process it away on gcc), so if you have a new sparse setup (as of two 
minutes ago ;), you can use this thing to check that arguments to macros 
do not have side effects.

Useful? You be the judge. But it was just a couple of lines in sparse, and
doing so also made it obvious how to clean up __builtin_constant_p() a lot
at the same time by just re-organizing things a bit.

My inliner and statement simplificator isn't perfect, so inline functions
sadly are not considered constant (or safe) even if they _do_ end up
returning a constant value (or be safe internally).

		Linus
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