tree 12d36d3ae0de09ea0fbc1140f9916d899bc7a5fa
parent f5cd71c5cf9404c1e1afcdc2e45712adeaddb3e9
author DRC <information@libjpeg-turbo.org> 1454476227 -0600
committer DRC <information@libjpeg-turbo.org> 1454476467 -0600

Opt. ARM64 SIMD decompr. for in-order pipelines

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:
https://github.com/mayeut/libjpeg-turbo/commit/6bad905034e6e73b33ebf07a74a6b72f58319f62
https://github.com/mayeut/libjpeg-turbo/commit/488dd7bf1726e2f6af6e9294ccf77b729fec1f20
https://github.com/mayeut/libjpeg-turbo/commit/4f4d057c1fb31d643536e6effb46a5946e15c465
https://github.com/mayeut/libjpeg-turbo/commit/d3198afc43450989a4fc63d2dcbe3272c8a0a3c1