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Re: [PATCH][IRA] Analysis of register usage of functions for usage by IRA.

From: Tom de Vries <Tom_deVries at mentor dot com>
To: Ulrich Weigand <uweigand at de dot ibm dot com>
Cc: Vladimir Makarov <vmakarov at redhat dot com>, Steven Bosscher <stevenb dot gcc at gmail dot com>, "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, Radovan Obradovic <robradovic at mips dot com>
Date: Thu, 4 Sep 2014 00:23:42 +0200
Subject: Re: [PATCH][IRA] Analysis of register usage of functions for usage by IRA.
Authentication-results: sourceware.org; auth=none
References: <201409031812 dot s83ICUxg004905 at d06av02 dot portsmouth dot uk dot ibm dot com>

On 03-09-14 20:12, Ulrich Weigand wrote:

Just for my curiosity, why is the second condition (after &&)
needed in this clause in the first place?

>  	      if (ira_hard_reg_set_intersection_p (regno, mode,
>+						   *crossed_calls_clobber_regs)
>+		  && (ira_hard_reg_set_intersection_p (regno, mode,
>  						       call_used_reg_set)
>-		      || HARD_REGNO_CALL_PART_CLOBBERED (regno, mode))

If a register is in crossed_calls_clobber_regs, can it ever*not*
be a call-clobbered register?

I *think* you're right that the second condition is not needed. But I'll leavethat for a follow-up patch.


Thanks,
- Tom

References:
- Re: [PATCH][IRA] Analysis of register usage of functions for usage by IRA.
  - From: Ulrich Weigand

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