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Re: [patch] regcprop fix for PR rtl-optimization/54300
- From: Steven Bosscher <stevenb dot gcc at gmail dot com>
- To: Richard Earnshaw <rearnsha at arm dot com>
- Cc: Eric Botcazou <ebotcazou at adacore dot com>, gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Tue, 19 Nov 2013 18:25:53 +0100
- Subject: Re: [patch] regcprop fix for PR rtl-optimization/54300
- Authentication-results: sourceware.org; auth=none
- References: <528B9527 dot 2050800 at arm dot com> <CABu31nOddrxBhG3EyPxi=2scYm8xVLbC12NkSvJ8OmDDGOOvBA at mail dot gmail dot com> <528B9E6F dot 4020707 at arm dot com>
On Tue, Nov 19, 2013 at 6:22 PM, Richard Earnshaw wrote:
>>> as a single-set insn (since the other operand, y, is not used) and
>>> replaces a use of x with a use of y. However, it fails to take into
>>> account that y has been clobbered in the insn itself.
>>
>> Ah, wait. Incorrect use of single_set().
>>
>> Try
>> ------
>> }
>>
>> - set = single_set (insn);
>> + set = multiple_sets (insn) ? NULL_RTX : single_set (insn);
>> extract_insn (insn);
>> if (! constrain_operands (1))
>> fatal_insn_not_found (insn);
>> preprocess_constraints ();
>> ------
...
> That won't handle
>
> parallel [ (set (x) (y))
> (clobber (y))]
Doesn't have to, AFAICT. y will be killed via kill_clobbered_value.
Ciao!
Steven