This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: ppc64 floating point usage [was Re: PPC64 Compiler bug !!]
- From: David Edelsohn <dje at watson dot ibm dot com>
- To: Eric Christopher <echristo at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Sat, 09 Aug 2003 19:27:14 -0400
- Subject: Re: ppc64 floating point usage [was Re: PPC64 Compiler bug !!]
>>>>> Eric Christopher writes:
Eric> Right, I can understand all of that, I worry that when you're choosing
Eric> register preferences it'll take an integer register in the unlikely case
Eric> that you have all of your floating point registers occupied giving you
Eric> an insn that can't match it's constraints. I thought * was normally used
Eric> when you have multiple alternatives and want to ignore one/multiple of
Eric> them for choosing register preferences. I just don't see a valid
Eric> constraint as a possible choice for register preference.
Eric> If I'm wrong here I apologize for the furor :)
Quoting the GCC Internals Manual, Machine Descriptions, Operand
Constraints, Constraint Modifier Characters:
"*
Says that the following character should be ignored when choosing
register preferences. * has no effect on the meaning of the
constraint as a constraint, and no effect on reloading."
Reload will ensure that the instruction matches its constraints.
David