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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 18:17:21 +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>
On Tue, Nov 19, 2013 at 5:43 PM, Richard Earnshaw wrote:
> PR 54300 is a problem in regcprop where the compiler sees
> (parallel [(set (x) (y)
> (set (y) (x)]) (REG_UNUSED (y))
>
> 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 ();
------
Ciao!
Steven