PowerPC optimization roadmap

Optimizing x264 library for PowerPC architecture puts it on par with other architectures that offer a close to optimal performance for library's users. This issue lists a pivotal changes to optimize x264 library for PowerPC architecture to keep it on track with x86 and Arm architectures.

• Build an infrastructure to use assembly language for function implementation !43
• Handle endianness variants by macros defined in asm.S !43
• Implement non-optimized functions (not implemented using C Intrinsic) !43
• Use Power ISA v3.0 for further optimizations
• Optimize additional functions

Using Power ISA v3.0:

Macro	Power ISA v3.0 instruction
LOAD_16_BYTE	lxvb16x (Load VSX Vector Byte*16 Indexed)
STORE_16_BYTE	stxvb16x (Store VSX Vector Byte*16 Indexed)
LOAD_8_HALFWORD	lxvh8x (Load VSX Vector Halfword*8 Indexed)
STORE_8_HALFWORD	stxvh8x (Store VSX Vector Halfword*8 Indexed)
LOAD_8_BYTE_H	lxvll (Load VSX Vector with Length Left-justified)
STORE_8_BYTE_H	stxvll (Store VSX Vector with Length Left-justified)
LOAD_4_BYTE_H	lxvll (Load VSX Vector with Length Left-justified)
STORE_4_BYTE_H	stxvll (Store VSX Vector with Length Left-justified)
ABS_BYTE	vabsdub (Vector Absolute Difference Unsigned Byte)
ABS_HALFWORD	vabsduh (Vector Absolute Difference Unsigned Halfword)

Function	Power ISA v3.0 instruction
zigzag_scan_8x8_field	vinserth (Vector Insert Halfword from VSR using immediate-specified index)
zigzag_sub_8x8	vinsertb (Vector Insert Byte from VSR using immediate-specified index)
zigzag_sub_4x4_field_neon	vinsertw, vinserth, stxvll (Vector Insert, Store VSX Vector)
zigzag_sub_4x4ac_field_neon	vinsertw, vinserth, stxvll (Vector Insert, Store VSX Vector)
zigzag_sub_4x4_frame_neon	vinsertw, vinserth, stxvll (Vector Insert, Store VSX Vector)
zigzag_sub_4x4ac_frame_neon	vinsertw, vinserth, stxvll (Vector Insert, Store VSX Vector)
pixel_ssd_nv12_core_altivec	vabsdub (Vector Absolute Difference Unsigned Byte)
pixel_var2_8x8_altivec	vabsdub (Vector Absolute Difference Unsigned Byte)
pixel_var2_8x16_altivec	vabsdub (Vector Absolute Difference Unsigned Byte)
pixel_vsad_altivec	vabsdub (Vector Absolute Difference Unsigned Byte)
deblock_v_chroma_altivec	vabsdub (Vector Absolute Difference Unsigned Byte)
deblock_h_chroma_altivec	vabsdub (Vector Absolute Difference Unsigned Byte)
deblock_h_chroma_422_altivec	vabsdub (Vector Absolute Difference Unsigned Byte)
deblock_h_chroma_mbaff_altivec	vabsdub (Vector Absolute Difference Unsigned Byte)
deblock_v_chroma_intra_altivec	vabsdub (Vector Absolute Difference Unsigned Byte)
decimate_score64_altivec	cnttzd (Count Trailing Zeros Doubleword)
coeff_last15_altivec	cnttzd (Count Trailing Zeros Doubleword)
coeff_last16_altivec	cnttzd (Count Trailing Zeros Doubleword)
coeff_last64_altivec	vctzw (Vector Count Trailing Zeros Word)
coeff_level_run8_altivec	cnttzd (Count Trailing Zeros Doubleword)
coeff_level_run15_altivec	cnttzd (Count Trailing Zeros Doubleword)
coeff_level_run16_altivec	cnttzd (Count Trailing Zeros Doubleword)

Implementing additional functions:

Function
zigzag_scan_8x8_field
zigzag_sub_8x8
mbtree_fix8_pack
mbtree_fix8_unpack
deblock_v_luma_intra
deblock_h_luma_intra
deblock_v8_luma
deblock_v8_luma_intra
predict_8x16c_p
dequant_4x4dc