Opt. ARM64 SIMD decompr. for in-order pipelines

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Decompression speedup relative to libjpeg-turbo 1.4.2 (ISLOW IDCT):
48-core ThunderX (RunAbove ARM Cloud), Linux, 64-bit: 60-113% (avg. 86%)
Cortex-A53 (Nexus 5X), Android, 64-bit: 6.8-27% (avg. 14%)
Cortex-A57 (Nexus 5X), Android, 64-bit: 2.0-14% (avg. 6.8%)

Decompression speedup relative to libjpeg-turbo 1.4.2 (IFAST IDCT):
48-core ThunderX (RunAbove ARM Cloud), Linux, 64-bit: 51-98% (avg. 75%)

Minimal speedup (1-5%) observed on iPhone 5S (Cortex-A7)

NOTE: This commit avoids the st3 instruction for non-Android and
non-Apple builds, which may cause a performance regression against
libjpeg-turbo 1.4.x on ARM64 systems that are running plain Linux.
Since ThunderX is the only platform known to suffer from slow ld3 and
st3 instructions, it is probably better to check for the CPU type
at run time and disable ld3/st3 only if ThunderX is detected.

This commit also enables the use of ld3 on Android platforms, which
should be a safe bet, at least for now.  This speeds up compression on
the afore-mentioned Nexus Cortex-A53 by 5.5-19% (avg. 12%) and on the
Nexus Cortex-A57 by 1.2-14% (avg. 6.3%), relative to the previous
commits.

This commit also removes unnecessary macros.

Refer to #52 for discussion.

Closes #52.

Based on:
6bad905034
488dd7bf17
4f4d057c1f
d3198afc43

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This commit is contained in:

DRC

2016-02-02 23:10:27 -06:00

parent f5cd71c5cf

commit cb49bb00d9

1 changed files with 762 additions and 836 deletions

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