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Re: [PATCH] Adjust builtin-bswap-6/7
- From: Jeff Law <law at redhat dot com>
- To: Andreas Krebbel <krebbel at linux dot vnet dot ibm dot com>, gcc-patches at gcc dot gnu dot org
- Date: Fri, 04 Apr 2014 11:51:54 -0600
- Subject: Re: [PATCH] Adjust builtin-bswap-6/7
- Authentication-results: sourceware.org; auth=none
- References: <20140404161818 dot GA26795 at bart>
On 04/04/14 10:18, Andreas Krebbel wrote:
the attached patch modifies the builtin-bswap-6/7 testcases in order
to prevent GCC from using math instead of a compare. Only with a
compare the folding in combine actually takes place.
Whether the return value is produce with a compare or not depends
again on the value of branch cost.
Ideally we would be able to do the folding also with the math trick
but it is probably not that easy since we have already lost the
information that in the end all we need is a 0 or a 1.
2014-04-04 Andreas Krebbel <Andreas.Krebbel@de.ibm.com>
* gcc.dg/builtin-bswap-6.c: Adjust return value to disable GCC
* gcc.dg/builtin-bswap-7.c: Likewise.