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Re: [Qemu-devel] [PULL 3/7] qxl: refactor rounding up to a nearest power
From: |
Radim Krčmář |
Subject: |
Re: [Qemu-devel] [PULL 3/7] qxl: refactor rounding up to a nearest power of 2 |
Date: |
Thu, 5 Mar 2015 16:35:36 +0100 |
2015-03-05 12:57+0800, Dongsheng Song:
> On Wed, Mar 4, 2015 at 10:30 PM, Gerd Hoffmann <address@hidden> wrote:
> > +/* round up to the nearest power of 2 (0 if overflow) */
> > +uint64_t pow2ceil(uint64_t value)
> > +{
> > + uint8_t nlz = clz64(value);
> > +
> > + if (is_power_of_2(value)) {
> > + return value;
> > + }
>
> please call clz64 after is_power_of_2.
All callers under clz64() are inline, so the optimizer can see that
there are no side effects and move the code if it would be faster;
I thought that separating it would only make the code uglier, because
QEMU doesn't allow lazy declarations ...
Markus had another design issue with this patch, so I'll send a v2 after
reaching the conclusion there.
Thanks.
- [Qemu-devel] [PULL 0/7] spice patch queue, Gerd Hoffmann, 2015/03/04
- [Qemu-devel] [PULL 3/7] qxl: refactor rounding up to a nearest power of 2, Gerd Hoffmann, 2015/03/04
- [Qemu-devel] [PULL 1/7] qxl: document minimal video memory for new modes, Gerd Hoffmann, 2015/03/04
- [Qemu-devel] [PULL 7/7] hmp: info spice: take out webdav, Gerd Hoffmann, 2015/03/04
- [Qemu-devel] [PULL 2/7] spice: fix invalid memory access to vga.vram, Gerd Hoffmann, 2015/03/04
- [Qemu-devel] [PULL 5/7] qxl: drop update_displaychangelistener call for secondary qxl devices, Gerd Hoffmann, 2015/03/04
- [Qemu-devel] [PULL 4/7] vga: refactor vram_size clamping and rounding, Gerd Hoffmann, 2015/03/04
- [Qemu-devel] [PULL 6/7] hmp: info spice: Show string channel name, Gerd Hoffmann, 2015/03/04
- Re: [Qemu-devel] [PULL 0/7] spice patch queue, Peter Maydell, 2015/03/08