Re: [PATCH 1/1] Speedfreq-SMI call clobbers ECX

[Andi Kleen]

> Please also note that these are not clobbers in the strict inline asm
> syntax, but rather dummy output values that correspond to actual

Outputs/Inputs are as bad as clobbers in triggering gcc reload ICEs.

> input parameters. I'd consider this a serious compiler flaw, if not
> bug, if these would not work. But let's not get into GCC vs.

It is, and it's (mostly) fixed in newer versions, but we're stuck with 
supporting the older compiler versions unfortunately.

> > For asms with so many clobbers explicit push/pop is usually safer.
> 
> Yes, but it is unneccessary overhead as the compiler can (should!)
> find more elegant ways to get those registers back if needed.

This code is not performance critical at all. Safer beats faster
any time in such cases.

-Andi

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/