Cycles: mix hair minimum width code with SSE intersection code

Gives 6.5% speedup for hair.blend from testsuite.

This commit was previously reverted, but should work ok now. Patch by Sv. Lockal.

1 files changed, 31 insertions, 9 deletions

diff --git a/intern/cycles/kernel/kernel_bvh_traversal.h b/intern/cycles/kernel/kernel_bvh_traversal.h
index 5309a80f31d..bfd72b0aa16 100644
--- a/intern/cycles/kernel/kernel_bvh_traversal.h
+++ b/intern/cycles/kernel/kernel_bvh_traversal.h
@@ -69,7 +69,7 @@ ccl_device bool BVH_FUNCTION_NAME
 	isect->u = 0.0f;
 	isect->v = 0.0f;
 
-#if defined(__KERNEL_SSE2__) && !FEATURE(BVH_HAIR_MINIMUM_WIDTH)
+#if defined(__KERNEL_SSE2__)
 	const shuffle_swap_t shuf_identity = shuffle_swap_identity();
 	const shuffle_swap_t shuf_swap = shuffle_swap_swap();
 	
@@ -96,7 +96,7 @@ ccl_device bool BVH_FUNCTION_NAME
 				bool traverseChild0, traverseChild1;
 				int nodeAddrChild1;
 
-#if !defined(__KERNEL_SSE2__) || FEATURE(BVH_HAIR_MINIMUM_WIDTH)
+#if !defined(__KERNEL_SSE2__)
 				/* Intersect two child bounding boxes, non-SSE version */
 				float t = isect->t;
 
@@ -154,15 +154,37 @@ ccl_device bool BVH_FUNCTION_NAME
 				/* Intersect two child bounding boxes, SSE3 version adapted from Embree */
 
 				/* fetch node data */
-				__m128 *bvh_nodes = (__m128*)kg->__bvh_nodes.data + nodeAddr*BVH_NODE_SIZE;
-				float4 cnodes = ((float4*)bvh_nodes)[3];
+				const __m128 *bvh_nodes = (__m128*)kg->__bvh_nodes.data + nodeAddr*BVH_NODE_SIZE;
+				const float4 cnodes = ((float4*)bvh_nodes)[3];
 
 				/* intersect ray against child nodes */
 				const __m128 tminmaxx = _mm_mul_ps(_mm_sub_ps(shuffle_swap(bvh_nodes[0], shufflexyz[0]), Psplat[0]), idirsplat[0]);
 				const __m128 tminmaxy = _mm_mul_ps(_mm_sub_ps(shuffle_swap(bvh_nodes[1], shufflexyz[1]), Psplat[1]), idirsplat[1]);
 				const __m128 tminmaxz = _mm_mul_ps(_mm_sub_ps(shuffle_swap(bvh_nodes[2], shufflexyz[2]), Psplat[2]), idirsplat[2]);
 
-				const __m128 tminmax = _mm_xor_ps(_mm_max_ps(_mm_max_ps(tminmaxx, tminmaxy), _mm_max_ps(tminmaxz, tsplat)), pn);
+				/* calculate { c0min, c1min, -c0max, -c1max} */
+				__m128 minmax = _mm_max_ps(_mm_max_ps(tminmaxx, tminmaxy), _mm_max_ps(tminmaxz, tsplat));
+				const __m128 tminmax = _mm_xor_ps(minmax, pn);
+
+#if FEATURE(BVH_HAIR_MINIMUM_WIDTH)
+				if(difl != 0.0f) {
+					float4 *tminmaxview = (float4*)&tminmax;
+					float &c0min = tminmaxview->x, &c1min = tminmaxview->y;
+					float &c0max = tminmaxview->z, &c1max = tminmaxview->w;
+
+					float hdiff = 1.0f + difl;
+					float ldiff = 1.0f - difl;
+					if(__float_as_int(cnodes.z) & PATH_RAY_CURVE) {
+						c0min = max(ldiff * c0min, c0min - extmax);
+						c0max = min(hdiff * c0max, c0max + extmax);
+					}
+					if(__float_as_int(cnodes.w) & PATH_RAY_CURVE) {
+						c1min = max(ldiff * c1min, c1min - extmax);
+						c1max = min(hdiff * c1max, c1max + extmax);
+					}
+				}
+#endif
+
 				const __m128 lrhit = _mm_cmple_ps(tminmax, shuffle<2, 3, 0, 1>(tminmax));
 
 				/* decide which nodes to traverse next */
@@ -181,7 +203,7 @@ ccl_device bool BVH_FUNCTION_NAME
 
 				if(traverseChild0 && traverseChild1) {
 					/* both children were intersected, push the farther one */
-#if !defined(__KERNEL_SSE2__) || FEATURE(BVH_HAIR_MINIMUM_WIDTH)
+#if !defined(__KERNEL_SSE2__)
 					bool closestChild1 = (c1min < c0min);
 #else
 					union { __m128 m128; float v[4]; } uminmax;
@@ -250,7 +272,7 @@ ccl_device bool BVH_FUNCTION_NAME
 							hit = bvh_triangle_intersect(kg, isect, P, idir, visibility, object, primAddr);
 
 						/* shadow ray early termination */
-#if defined(__KERNEL_SSE2__) && !FEATURE(BVH_HAIR_MINIMUM_WIDTH)
+#if defined(__KERNEL_SSE2__)
 						if(hit) {
 							if(visibility == PATH_RAY_SHADOW_OPAQUE)
 								return true;
@@ -276,7 +298,7 @@ ccl_device bool BVH_FUNCTION_NAME
 					bvh_instance_push(kg, object, ray, &P, &idir, &isect->t, tmax);
 #endif
 
-#if defined(__KERNEL_SSE2__) && !FEATURE(BVH_HAIR_MINIMUM_WIDTH)
+#if defined(__KERNEL_SSE2__)
 					Psplat[0] = _mm_set_ps1(P.x);
 					Psplat[1] = _mm_set_ps1(P.y);
 					Psplat[2] = _mm_set_ps1(P.z);
@@ -306,7 +328,7 @@ ccl_device bool BVH_FUNCTION_NAME
 			bvh_instance_pop(kg, object, ray, &P, &idir, &isect->t, tmax);
 #endif
 
-#if defined(__KERNEL_SSE2__) && !FEATURE(BVH_HAIR_MINIMUM_WIDTH)
+#if defined(__KERNEL_SSE2__)
 			Psplat[0] = _mm_set_ps1(P.x);
 			Psplat[1] = _mm_set_ps1(P.y);
 			Psplat[2] = _mm_set_ps1(P.z);