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Re: [Qemu-devel] [5281] Use the new concat_i32_i64 op for std and stda
From: |
Paul Brook |
Subject: |
Re: [Qemu-devel] [5281] Use the new concat_i32_i64 op for std and stda |
Date: |
Sun, 21 Sep 2008 17:36:25 +0100 |
User-agent: |
KMail/1.9.9 |
> > It's more efficient to not use concat_i32_i64 on 64-bit targets.
> > See patch below. I'll let you decide if you want to apply or ignore it.
>
> Good point. How about adding instead a concat_i64_i64 starting from this
> piece:
I'd call it concat32_i64 (c.f. extu_i32_i64 v.s. ext32u_i64).
> > + tcg_gen_shli_i64(dest, high, 32);
> > + tcg_gen_ext32u_i64(low, low);
> > + tcg_gen_or_i64(dest, dest, low);
>
> and also add defines for concat_tl_i64? That would be both clean and
> efficient.
Sounds reasonable. The cheat for tl->i64 on 32-bit hosts is ok if it's
confined to tcg-opc.h.
> I think ldd on i386 would benefit from a reverse operation (64 to two
> 32/64 bit words).
64 to 32 should be much easier for TCG to optimize automatically. It's just a
a series of copies, and can often be implemented without requiring any extra
temporaries. The 32 to 64 case is a trickier because you generally need
additional temporaries for type correctness and have to propagate all the
zeros through the 64-bit logical or.
Paul
- [Qemu-devel] [5281] Use the new concat_i32_i64 op for std and stda, Blue Swirl, 2008/09/21
- Re: [Qemu-devel] [5281] Use the new concat_i32_i64 op for std and stda, Paul Brook, 2008/09/21
- Re: [Qemu-devel] [5281] Use the new concat_i32_i64 op for std and stda, Blue Swirl, 2008/09/21
- Re: [Qemu-devel] [5281] Use the new concat_i32_i64 op for std and stda, Blue Swirl, 2008/09/21
- Re: [Qemu-devel] [5281] Use the new concat_i32_i64 op for std and stda, Paul Brook, 2008/09/21
- Re: [Qemu-devel] [5281] Use the new concat_i32_i64 op for std and stda, Blue Swirl, 2008/09/21
- Re: [Qemu-devel] [5281] Use the new concat_i32_i64 op for std and stda, Thiemo Seufer, 2008/09/21
- Re: [Qemu-devel] [5281] Use the new concat_i32_i64 op for std and stda, Blue Swirl, 2008/09/22
- Re: [Qemu-devel] [5281] Use the new concat_i32_i64 op for std and stda, Paul Brook, 2008/09/22
- Re: [Qemu-devel] [5281] Use the new concat_i32_i64 op for std and stda,
Paul Brook <=