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Re: [PATCH] Do not allow non-allocatable registers in scratch_operand

From: Jeff Law <law at redhat dot com>
To: Segher Boessenkool <segher at kernel dot crashing dot org>
Cc: gcc-patches at gcc dot gnu dot org
Date: Fri, 19 Sep 2014 10:35:49 -0600
Subject: Re: [PATCH] Do not allow non-allocatable registers in scratch_operand
Authentication-results: sourceware.org; auth=none
References: <74729933448c3ec81b326073757add5ddb1165a7 dot 1410826448 dot git dot segher at kernel dot crashing dot org> <541BC526 dot 8040406 at redhat dot com> <20140919122116 dot GB13688 at gate dot crashing dot org>

On 09/19/14 06:21, Segher Boessenkool wrote:

On Thu, Sep 18, 2014 at 11:54:46PM -0600, Jeff Law wrote:

Shouldn't you be testing if the register is fixed rather than its class?
  Or maybe both?


register_operand (via general_operand) uses operand_reg_set for this; it is
initialised via the regclass NO_REGS too (and other things).

This would work for us (rs6000) too, or indeed fixed_regs[], or even wider
classes.  I have no idea if it would hurt other targets though, and I have
no desire to test all weirdo targets ;-)

Can't blame you for that :-)

Thanks for the pointer to operand_reg_set. Having walked through someof that code, I think we're OK just looking at the class like youroriginal patch did.


Concerns withdrawn.  Patch approved.

Jeff

References:
- [PATCH] Do not allow non-allocatable registers in scratch_operand
  - From: Segher Boessenkool
- Re: [PATCH] Do not allow non-allocatable registers in scratch_operand
  - From: Jeff Law
- Re: [PATCH] Do not allow non-allocatable registers in scratch_operand
  - From: Segher Boessenkool

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