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Re: scavanging a reg
- To: Aldy Hernandez <aldyh at redhat dot com>
- Subject: Re: scavanging a reg
- From: David Edelsohn <dje at watson dot ibm dot com>
- Date: Tue, 13 Nov 2001 11:25:42 -0500
- Cc: gcc at gcc dot gnu dot org
>>>>> Aldy Hernandez writes:
Aldy> i need a GPR at epilogue/prologue time so i can load and save to the
Aldy> VRSAVE register (which can only be moved to and fro GPRs).
Aldy> what's the best route for this? can i iterate through "regs_ever_live"
Aldy> and get one from there? i mean, reload is already done so we won't need
Aldy> any more registers.
I don't know what dependency ordering your have, but can you use
GPR12 which the prologue and epilogue already uses as an intermediate for
saving the condition register? If you use r12, you need to be careful not
to trample the CR information for any of the ABI codepaths.
David