Cycles: Add BVH8 and packeted triangle intersection

This is an initial implementation of BVH8 optimization structure
and packated triangle intersection. The aim is to get faster ray
to scene intersection checks.

    Scene                BVH4      BVH8
barbershop_interior    10:24.94   10:10.74
bmw27                  02:41.25   02:38.83
classroom              08:16.49   07:56.15
fishy_cat              04:24.56   04:17.29
koro                   06:03.06   06:01.45
pavillon_barcelona     09:21.26   09:02.98
victor                 23:39.65   22:53.71

As memory goes, peak usage raises by about 4.7% in a complex
scenes.

Note that BVH8 is disabled when using OSL, this is because OSL
kernel does not get per-microarchitecture optimizations and
hence always considers BVH3 is used.

Original BVH8 patch from Anton Gavrikov.
Batched triangles intersection from Victoria Zhislina.
Extra work and tests and fixes from Maxym Dmytrychenko.

1 files changed, 3 insertions, 0 deletions

diff --git a/intern/cycles/device/device_cpu.cpp b/intern/cycles/device/device_cpu.cpp
index e92bbbfa6e6..5b3761f8353 100644
--- a/intern/cycles/device/device_cpu.cpp
+++ b/intern/cycles/device/device_cpu.cpp
@@ -1031,6 +1031,9 @@ void device_cpu_info(vector<DeviceInfo>& devices)
 	if(system_cpu_support_sse2()) {
 		info.bvh_layout_mask |= BVH_LAYOUT_BVH4;
 	}
+	if (system_cpu_support_avx2()) {
+		info.bvh_layout_mask |= BVH_LAYOUT_BVH8;
+	}
 	info.has_volume_decoupled = true;
 	info.has_osl = true;
 	info.has_half_images = true;