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Re: RFA: cache enabled attribute by insn code
- From: Richard Earnshaw <rearnsha at arm dot com>
- To: Christophe Lyon <christophe dot lyon at linaro dot org>, Jeff Law <law at redhat dot com>, "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, rsandifo at linux dot vnet dot ibm dot com
- Date: Tue, 27 May 2014 16:15:47 +0100
- Subject: Re: RFA: cache enabled attribute by insn code
- Authentication-results: sourceware.org; auth=none
- References: <87k39gkgq0 dot fsf at talisman dot default> <537B95E9 dot 1010203 at redhat dot com> <87iop0i13e dot fsf at talisman dot default> <537F9126 dot 5080904 at redhat dot com> <CAKdteOaYVgFZg5aUWUj9K7LPgmiGoT3iFiiaVbc-eSUKv22HCQ at mail dot gmail dot com> <87zji31fh7 dot fsf at sandifor-thinkpad dot stglab dot manchester dot uk dot ibm dot com>
On 27/05/14 15:08, Richard Sandiford wrote:
> Hmm, is this because of "insn_enabled"? If so, how did that work before
> the patch? LRA already assumed that the "enabled" attribute didn't depend
> on the operands.
Huh! "enabled" can be applied to each alternative. Alternatives are
selected based on the operands. If LRA can't cope with that we have a
serious problem. In fact, a pattern that matches but has no enabled
alternatives is meaningless and guaranteed to cause problems during
register allocation.
R.