armv7: Add optimised untransformed scanline fetchers r5g6b5 & a1r5g5b5

lowlevel-blt-bench results on Cortex-A7 for a couple of sample operations
that utilise these fetchers are below.

add_0565_8888:

       Before          After
      Mean StdDev     Mean StdDev   Confidence   Change
L1    75.4   0.38    147.5   0.90    100.00%     +95.7%
L2    72.3   0.36    129.3   0.57    100.00%     +79.0%
M     64.4   0.05     94.6   0.90    100.00%     +46.8%
HT    35.8   0.03     42.3   0.26    100.00%     +18.1%
VT    29.9   0.04     34.3   0.31    100.00%     +14.5%
R     26.1   0.02     28.6   0.11    100.00%      +9.4%
RT    12.2   0.06     13.1   0.15    100.00%      +7.9%

add_1555_8888:

       Before          After
      Mean StdDev     Mean StdDev   Confidence   Change
L1    73.3   0.38    160.7   0.89    100.00%    +119.2%
L2    69.8   0.08    139.1   0.74    100.00%     +99.4%
M     62.2   0.03    100.4   0.76    100.00%     +61.4%
HT    35.1   0.03     42.9   0.42    100.00%     +22.1%
VT    29.5   0.03     34.7   0.33    100.00%     +17.8%
R     25.8   0.02     28.7   0.27    100.00%     +11.4%
RT    12.1   0.02     13.2   0.15    100.00%      +8.5%

---

For the record, I tried writing an a8 fetcher, but benchmarking indicated that
it couldn't improve upon the ARMv6 a8 fetcher results.

I also tried adding prefetch to the above fetchers - since they are the
first iterator in a chain and won't benefit from write-allocate caches, you
might think that this would help. Benchmarking indicated otherwise.

2 files changed, 33 insertions, 0 deletions

diff --git a/pixman/pixman-arm-neon-asm.S b/pixman/pixman-arm-neon-asm.S
index 5c1c30a..f48f773 100644
--- a/pixman/pixman-arm-neon-asm.S
+++ b/pixman/pixman-arm-neon-asm.S
@@ -496,6 +496,16 @@ generate_composite_function \
     pixman_composite_src_0565_8888_process_pixblock_tail, \
     pixman_composite_src_0565_8888_process_pixblock_tail_head
 
+generate_composite_function_single_scanline \
+    pixman_get_scanline_r5g6b5_asm_neon, 16, 0, 32, \
+    FLAG_DST_WRITEONLY | FLAG_DEINTERLEAVE_32BPP, \
+    8, /* number of pixels, processed in a single block */ \
+    default_init, \
+    default_cleanup, \
+    pixman_composite_src_0565_8888_process_pixblock_head, \
+    pixman_composite_src_0565_8888_process_pixblock_tail, \
+    pixman_composite_src_0565_8888_process_pixblock_tail_head
+
 /******************************************************************************/
 
 .macro pixman_composite_add_8_8_process_pixblock_head
@@ -3227,6 +3237,16 @@ generate_composite_function \
     pixman_composite_src_1555_8888_process_pixblock_tail, \
     pixman_composite_src_1555_8888_process_pixblock_tail_head
 
+generate_composite_function_single_scanline \
+    pixman_get_scanline_a1r5g5b5_asm_neon, 16, 0, 32, \
+    FLAG_DST_WRITEONLY, \
+    8, /* number of pixels, processed in a single block */ \
+    default_init, \
+    default_cleanup, \
+    pixman_composite_src_1555_8888_process_pixblock_head, \
+    pixman_composite_src_1555_8888_process_pixblock_tail, \
+    pixman_composite_src_1555_8888_process_pixblock_tail_head
+
 /******************************************************************************/
 
 generate_composite_function_nearest_scanline \
diff --git a/pixman/pixman-arm-neon.c b/pixman/pixman-arm-neon.c
index b597b82..d4675f1 100644
--- a/pixman/pixman-arm-neon.c
+++ b/pixman/pixman-arm-neon.c
@@ -165,6 +165,9 @@ PIXMAN_ARM_BIND_SCALED_BILINEAR_SRC_A8_DST (SKIP_ZERO_SRC, neon, 8888_8_8888, OV
 PIXMAN_ARM_BIND_SCALED_BILINEAR_SRC_A8_DST (SKIP_ZERO_SRC, neon, 8888_8_8888, ADD,
                                             uint32_t, uint32_t)
 
+PIXMAN_ARM_BIND_GET_SCANLINE (neon, r5g6b5)
+PIXMAN_ARM_BIND_GET_SCANLINE (neon, a1r5g5b5)
+
 void
 pixman_composite_src_n_8_asm_neon (int32_t   w,
                                    int32_t   h,
@@ -438,6 +441,15 @@ static const pixman_fast_path_t arm_neon_fast_paths[] =
     { PIXMAN_OP_NONE },
 };
 
+static const pixman_iter_info_t arm_neon_iters[] =
+{
+    PIXMAN_ARM_UNTRANSFORMED_COVER_FETCHER (neon, r5g6b5),
+
+    PIXMAN_ARM_UNTRANSFORMED_COVER_FETCHER (neon, a1r5g5b5),
+
+    { PIXMAN_null },
+};
+
 void
 pixman_composite_scanline_src_mask_asm_neon (int32_t         w,
                                              uint32_t       *dst,
@@ -481,6 +493,7 @@ _pixman_implementation_create_arm_neon (pixman_implementation_t *fallback)
     imp->combine_32[PIXMAN_OP_OUT_REVERSE] = neon_combine_out_reverse_u;
     imp->combine_32[PIXMAN_OP_ADD] = neon_combine_add_u;
 
+    imp->iter_info = arm_neon_iters;
     imp->blt = arm_neon_blt;
     imp->fill = arm_neon_fill;