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PowerPC gas -many
- From: Alan Modra <amodra at bigpond dot net dot au>
- To: binutils at sources dot redhat dot com
- Cc: Anton Blanchard <anton at samba dot org>, Paul Mackerras <paulus at au1 dot ibm dot com>
- Date: Tue, 2 Sep 2003 10:19:25 +0930
- Subject: PowerPC gas -many
The PowerPC gas -many option is supposed to "Generate code for any
architecture (PWR/PWRX/PPC)". At some point -many lost its meaning.
For instance, ppc405 opcodes like "macchw" are not accepted under
-many. The same goes for BookE and Power4.
An example where -many might be useful is assembly code that's
conditionally executed at runtime depending on the type of processor
detected. Unless someone raises serious objections, I'll work on fixing
-many.
I realize there are some difficulties. For instance, some instructions
have different encodings (eg. Power4 branch hint bits), or different
operands (eg. cmp) depending on the flavour we are assembling. Perhaps
the differing encoding problem could be fixed by allowing -many to
modify the current set of accepted instructions, so that eg.
"-mpower4 -many" means assemble for any ppc arch but choose power4 in
preference to other possible encodings.
Comments?
--
Alan Modra
IBM OzLabs - Linux Technology Centre