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[Bug tree-optimization/44955] over-prefetched for arrays of complex number
- From: "rakdver at kam dot mff dot cuni dot cz" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 15 Jul 2010 17:44:17 -0000
- Subject: [Bug tree-optimization/44955] over-prefetched for arrays of complex number
- References: <bug-44955-18740@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #2 from rakdver at kam dot mff dot cuni dot cz 2010-07-15 17:44 -------
Subject: Re: over-prefetched for arrays of
complex number
> This is a piece of code that shows the two prefetches for b.
>
> mulss %xmm4, %xmm5
> addq $8, %rdx
> prefetcht0 96(%r11)
> prefetcht0 100(%r11)
> subss %xmm2, %xmm1
> addss %xmm5, %xmm0
>
> In collecting memory references for the loops, the array of the imagine part
> is put into the different group from that of the real part (and thus two
> prefetches are generated).
>
> eference 0x2d61e70:
> group 0x2d63630 (base REALPART_EXPR <*b_64(D)...
>
> Reference 0x2d615e0:
> group 0x2d40f40 (base IMAGPART_EXPR <*b_64(D)...
>
> I think that the base should be reduced to the same, with a offset of 4.
> So they can be in the same group.
agreed,
Zdenek
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44955