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Re: mutex in frame code
- To: David Edelsohn <dje at watson dot ibm dot com>
- Subject: Re: mutex in frame code
- From: Zack Weinberg <zack at rabi dot columbia dot edu>
- Date: Mon, 01 Feb 1999 13:48:20 -0500
- cc: egcs at egcs dot cygnus dot com
On Mon, 01 Feb 1999 13:16:28 -0500, David Edelsohn wrote:
> The POWER and PowerPC architecture do not describe a nested set
>which is exactly what is assumed by this entire -march= discussion. You
>and Richard and others are relying on the fact that -march=X is a complete
>subset of -march=X+1. On POWER and PowerPC that is not the case.
>
> The POWER and PowerPC architectures implement a number of features
>such as POWER/2 extensions, PowerPC general-purpose extensions, PowerPC
>graphics extensions, presence of floating-point, etc. Specifying which
>combinarion of extensions is specified by processor -- CPU -- not by
>architecture. Using the option -march= but specifying CPU is confusing
>and incorrect.
Any number of CPU implementations may implement the same set of
extensions, yesno? And they might have different cache / scheduling
characteristics?
It seems to me that -march=<list of extensions> would be appropriate,
perhaps with aliases for common sets. -mtune can specify cache and
scheduling parameters, and -mcpu select both.
zw