NEON fast path for box blur
Calculate 8 channels in parallel by using 16-bits to store each channel. Due to the limitation of VQRDMULH, (int16 * int16 * 2 + 0x8000) >> 16, the fast path can only support kernelSize < 128.
8 significant bits are kept at least in each stage, the final error should less-equal than 1.
Pre-fetching memory for X-direction read. In fact pre-fetching memory doesn't help much for Y direction read, since it is a waste to load a cache line for only read 8 bytes.(I left it there to keep the symmetry. pre-fetch is cheap :) )
bench data on Nexus 10
before:
running bench [640 480] blur_image_filter_large_10.00_10.00 8888: cmsecs = 25081.48
running bench [640 480] blur_image_filter_small_10.00_10.00 8888: cmsecs = 25038.04
running bench [640 480] blur_image_filter_large_1.00_1.00 8888: cmsecs = 25209.04
running bench [640 480] blur_image_filter_small_1.00_1.00 8888: cmsecs = 24928.01
running bench [640 480] blur_image_filter_large_0.00_1.00 8888: cmsecs = 17160.98
running bench [640 480] blur_image_filter_large_0.00_10.00 8888: cmsecs = 17924.11
running bench [640 480] blur_image_filter_large_1.00_0.00 8888: cmsecs = 14609.19
running bench [640 480] blur_image_filter_large_10.00_0.00 8888: cmsecs = 14625.91
after:
running bench [640 480] blur_image_filter_large_10.00_10.00 8888: cmsecs = 14848.42
running bench [640 480] blur_image_filter_small_10.00_10.00 8888: cmsecs = 16037.29
running bench [640 480] blur_image_filter_large_1.00_1.00 8888: cmsecs = 14819.55
running bench [640 480] blur_image_filter_small_1.00_1.00 8888: cmsecs = 14563.69
running bench [640 480] blur_image_filter_large_0.00_1.00 8888: cmsecs = 11905.34
running bench [640 480] blur_image_filter_large_0.00_10.00 8888: cmsecs = 11883.85
running bench [640 480] blur_image_filter_large_1.00_0.00 8888: cmsecs = 9576.51
running bench [640 480] blur_image_filter_large_10.00_0.00 8888: cmsecs = 9793.84
BUG=
R=senorblanco@chromium.org, mtklein@google.com, reed@google.com, kevin.petit@arm.com, kevin.petit.arm@gmail.com
Author: zheng.xu@arm.com
Review URL: https://codereview.chromium.org/105893003
git-svn-id: http://skia.googlecode.com/svn/trunk@13036 2bbb7eff-a529-9590-31e7-b0007b416f81
4 files changed