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Re: Questions about the instruction selection for sse2 intrinsicwith -O optimization
- From: Jim Wilson <wilson at specifixinc dot com>
- To: haibo <chbchb1130 at sina dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: Tue, 09 Mar 2004 18:05:00 -0800
- Subject: Re: Questions about the instruction selection for sse2 intrinsicwith -O optimization
- References: <E1B0Y2O-0003fb-00@deer.gmane.org>
haibo wrote:
> I wonder when and where gcc do these things in source code,
> I have tried to step into the source code,and it do reach the code that
> processes the _mm_insert_epi16 intrinsics and emit the rtl for it,but
> when gcc do insn match,It doesn't math it with sse2_pinsrw.
This is a bit too vague to easily answer.
You didn't provide a proper testcase that I can compile. You didn't
provide example RTL dumps, so I am not sure exactly what you are
complaining about.
I am guessing that the pattern that the sse2_pinsrw pattern emitted is
also matched by other patterns, and hence you got other instructions.
This might be an optimization. This might be an accidental bug. It
might be a false impression on your part that the mm_insert_epi16
intrinsic should always map to a pinsrw instruction. There isn't enough
information here to tell.
--
Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com