Cycles: Implement denoising option for reducing noise in the rendered image

This commit contains the first part of the new Cycles denoising option,
which filters the resulting image using information gathered during rendering
to get rid of noise while preserving visual features as well as possible.

To use the option, enable it in the render layer options. The default settings
fit a wide range of scenes, but the user can tweak individual settings to
control the tradeoff between a noise-free image, image details, and calculation
time.

Note that the denoiser may still change in the future and that some features
are not implemented yet. The most important missing feature is animation
denoising, which uses information from multiple frames at once to produce a
flicker-free and smoother result. These features will be added in the future.

Finally, thanks to all the people who supported this project:

- Google (through the GSoC) and Theory Studios for sponsoring the development
- The authors of the papers I used for implementing the denoiser (more details
  on them will be included in the technical docs)
- The other Cycles devs for feedback on the code, especially Sergey for
  mentoring the GSoC project and Brecht for the code review!
- And of course the users who helped with testing, reported bugs and things
  that could and/or should work better!

1 files changed, 40 insertions, 0 deletions

diff --git a/intern/cycles/kernel/kernels/cpu/filter_avx2.cpp b/intern/cycles/kernel/kernels/cpu/filter_avx2.cpp
new file mode 100644
index 00000000000..c22ec576254
--- /dev/null
+++ b/intern/cycles/kernel/kernels/cpu/filter_avx2.cpp
@@ -0,0 +1,40 @@
+/*
+ * Copyright 2011-2017 Blender Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* Optimized CPU kernel entry points. This file is compiled with AVX2
+ * optimization flags and nearly all functions inlined, while kernel.cpp
+ * is compiled without for other CPU's. */
+
+#include "util/util_optimization.h"
+
+#ifndef WITH_CYCLES_OPTIMIZED_KERNEL_AVX2
+#  define KERNEL_STUB
+#else
+/* SSE optimization disabled for now on 32 bit, see bug #36316 */
+#  if !(defined(__GNUC__) && (defined(i386) || defined(_M_IX86)))
+#    define __KERNEL_SSE__
+#    define __KERNEL_SSE2__
+#    define __KERNEL_SSE3__
+#    define __KERNEL_SSSE3__
+#    define __KERNEL_SSE41__
+#    define __KERNEL_AVX__
+#    define __KERNEL_AVX2__
+#  endif
+#endif  /* WITH_CYCLES_OPTIMIZED_KERNEL_AVX2 */
+
+#include "kernel/filter/filter.h"
+#define KERNEL_ARCH cpu_avx2
+#include "kernel/kernels/cpu/filter_cpu_impl.h"