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Re: [RFC] POWER8 default for PPC64LE

From: Jeff Law <law at redhat dot com>
To: David Edelsohn <dje dot gcc at gmail dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>
Cc: Peter Bergner <bergner at vnet dot ibm dot com>, Michael Meissner <meissner at linux dot vnet dot ibm dot com>, Ulrich Weigand <uweigand at de dot ibm dot com>
Date: Wed, 14 Jan 2015 13:36:44 -0700
Subject: Re: [RFC] POWER8 default for PPC64LE
Authentication-results: sourceware.org; auth=none
References: <CAGWvnyk5WC96w5RbOq-D_2Pytur+bhqoHA5ZpRBe5Q5iwyiStg at mail dot gmail dot com>

On 01/14/15 13:32, David Edelsohn wrote:

The PPC64LE ABI specifies POWER8 ISA as the minimum hardware
requierment.  Currently, Linux distributions are building the
toolchain using --with-cpu=power7 or power8, as they wish.  GCC
defaults to essentially the POWER4 ISA.

The appended patch changes the default for PPC64LE to POWER8 (ISA
2.7).  32-bit PPC SVR4 is not really defined, but it is left unchanged
with no minimum ISA.

The default ISA can be overridden using --with-cpu= and we presume
that Linux distributions and users will continue to configure as they
require for their deployment.

* config/rs6000/default64.h (TARGET_DEFAULT) [LITTLE_ENDIAN]: Use ISA
2.7 (POWER8).

Given you've got a new ABI in play here, seems like the perfect time tobump the default ISA to something reasonable.


jeff

Follow-Ups:
- Re: [RFC] POWER8 default for PPC64LE
  - From: Peter Bergner

References:
- [RFC] POWER8 default for PPC64LE
  - From: David Edelsohn

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