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Re: [PATCH PR62011]
- From: Yuri Rumyantsev <ysrumyan at gmail dot com>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: "H.J. Lu" <hjl dot tools at gmail dot com>, gcc-patches <gcc-patches at gcc dot gnu dot org>, Uros Bizjak <ubizjak at gmail dot com>
- Date: Fri, 15 Aug 2014 16:26:12 +0400
- Subject: Re: [PATCH PR62011]
- Authentication-results: sourceware.org; auth=none
- References: <CAEoMCqRQgLeT9EpwxmX99wi=Fzc3CN2ZE4dQGATTVd8xmV1nNA at mail dot gmail dot com> <CAMe9rOqbe3Pjv=T5rid_UQje+vQEXXR8GjLcEWx+Yr7c3KCQAg at mail dot gmail dot com> <CAEoMCqT8LMm27N8tEiY3Q=W1b2g6s5SR9KT4P1MhsV8q3Mm6MA at mail dot gmail dot com> <CAEoMCqTWviiyX=LcL-pMCUhniqazcmtHpb47LCjL8vadHxrFaA at mail dot gmail dot com> <20140815115440 dot GS1784 at tucnak dot redhat dot com>
Jakub,
Is it important to have correct value for length attribute for Big Cores?
As I new this attribute is used for code layout alignment.
2014-08-15 15:54 GMT+04:00 Jakub Jelinek <jakub@redhat.com>:
> On Fri, Aug 15, 2014 at 03:45:33PM +0400, Yuri Rumyantsev wrote:
>> gcc/ChangeLog
>> 2014-08-15 Yuri Rumyantsev <ysrumyan@gmail.com>
>>
>> PR target/62011
>> * config/i386/i386-protos.h (ix86_avoid_false_dep_for_bm): New function
>> prototype.
>> * config/i386/i386.c (ix86_avoid_false_dep_for_bm): New function.
>> * config/i386/i386.h (TARGET_AVOID_FALSE_DEP_FOR_BM) New macros.
>> * config/i386/i386.md (ctz<mode>2, clz<mode>2_lzcnt, popcount<mode>2,
>> *popcount<mode>2_cmp, *popcountsi2_cmp_zext): Output zeroing
>> destination register for unary bit-manipulation instructions
>> if required.
>> * config/i386/x86-tune.def (X86_TUNE_AVOID_FALSE_DEP_FOR_BM): New.
>
> --- config/i386/i386.md (revision 213842)
> +++ config/i386/i386.md (working copy)
> @@ -12111,7 +12111,13 @@
> ""
> {
> if (TARGET_BMI)
> - return "tzcnt{<imodesuffix>}\t{%1, %0|%0, %1}";
> + {
> + if (ix86_avoid_false_dep_for_bm (insn, operands))
> + return "xor{<imodesuffix>}\t%0, %0\n\t"
> + "tzcnt{<imodesuffix>}\t{%1, %0|%0, %1}";
> + else
> + return "tzcnt{<imodesuffix>}\t{%1, %0|%0, %1}";
> + }
> else if (optimize_function_for_size_p (cfun))
> ;
> else if (TARGET_GENERIC)
>
> etc., this will make lenght attribute incorrect though.
>
> Jakub