Cycles: merge of cycles-x branch, a major update to the renderer

This includes much improved GPU rendering performance, viewport interactivity,
new shadow catcher, revamped sampling settings, subsurface scattering anisotropy,
new GPU volume sampling, improved PMJ sampling pattern, and more.

Some features have also been removed or changed, breaking backwards compatibility.
Including the removal of the OpenCL backend, for which alternatives are under
development.

Release notes and code docs:
https://wiki.blender.org/wiki/Reference/Release_Notes/3.0/Cycles
https://wiki.blender.org/wiki/Source/Render/Cycles

Credits:
* Sergey Sharybin
* Brecht Van Lommel
* Patrick Mours (OptiX backend)
* Christophe Hery (subsurface scattering anisotropy)
* William Leeson (PMJ sampling pattern)
* Alaska (various fixes and tweaks)
* Thomas Dinges (various fixes)

For the full commit history, see the cycles-x branch. This squashes together
all the changes since intermediate changes would often fail building or tests.

Ref T87839, T87837, T87836
Fixes T90734, T89353, T80267, T80267, T77185, T69800

1 files changed, 124 insertions, 0 deletions

diff --git a/intern/cycles/device/cpu/kernel_function.h b/intern/cycles/device/cpu/kernel_function.h
new file mode 100644
index 00000000000..aa18720cc24
--- /dev/null
+++ b/intern/cycles/device/cpu/kernel_function.h
@@ -0,0 +1,124 @@
+/*
+ * Copyright 2011-2021 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.
+ */
+
+#pragma once
+
+#include "util/util_debug.h"
+#include "util/util_system.h"
+
+CCL_NAMESPACE_BEGIN
+
+/* A wrapper around per-microarchitecture variant of a kernel function.
+ *
+ * Provides a function-call-like API which gets routed to the most suitable implementation.
+ *
+ * For example, on a computer which only has SSE4.1 the kernel_sse41 will be used. */
+template<typename FunctionType> class CPUKernelFunction {
+ public:
+  CPUKernelFunction(FunctionType kernel_default,
+                    FunctionType kernel_sse2,
+                    FunctionType kernel_sse3,
+                    FunctionType kernel_sse41,
+                    FunctionType kernel_avx,
+                    FunctionType kernel_avx2)
+  {
+    kernel_info_ = get_best_kernel_info(
+        kernel_default, kernel_sse2, kernel_sse3, kernel_sse41, kernel_avx, kernel_avx2);
+  }
+
+  template<typename... Args> inline auto operator()(Args... args) const
+  {
+    assert(kernel_info_.kernel);
+
+    return kernel_info_.kernel(args...);
+  }
+
+  const char *get_uarch_name() const
+  {
+    return kernel_info_.uarch_name;
+  }
+
+ protected:
+  /* Helper class which allows to pass human-readable microarchitecture name together with function
+   * pointer. */
+  class KernelInfo {
+   public:
+    KernelInfo() : KernelInfo("", nullptr)
+    {
+    }
+
+    /* TODO(sergey): Use string view, to have higher-level functionality (i.e. comparison) without
+     * memory allocation. */
+    KernelInfo(const char *uarch_name, FunctionType kernel)
+        : uarch_name(uarch_name), kernel(kernel)
+    {
+    }
+
+    const char *uarch_name;
+    FunctionType kernel;
+  };
+
+  KernelInfo get_best_kernel_info(FunctionType kernel_default,
+                                  FunctionType kernel_sse2,
+                                  FunctionType kernel_sse3,
+                                  FunctionType kernel_sse41,
+                                  FunctionType kernel_avx,
+                                  FunctionType kernel_avx2)
+  {
+    /* Silence warnings about unused variables when compiling without some architectures. */
+    (void)kernel_sse2;
+    (void)kernel_sse3;
+    (void)kernel_sse41;
+    (void)kernel_avx;
+    (void)kernel_avx2;
+
+#ifdef WITH_CYCLES_OPTIMIZED_KERNEL_AVX2
+    if (DebugFlags().cpu.has_avx2() && system_cpu_support_avx2()) {
+      return KernelInfo("AVX2", kernel_avx2);
+    }
+#endif
+
+#ifdef WITH_CYCLES_OPTIMIZED_KERNEL_AVX
+    if (DebugFlags().cpu.has_avx() && system_cpu_support_avx()) {
+      return KernelInfo("AVX", kernel_avx);
+    }
+#endif
+
+#ifdef WITH_CYCLES_OPTIMIZED_KERNEL_SSE41
+    if (DebugFlags().cpu.has_sse41() && system_cpu_support_sse41()) {
+      return KernelInfo("SSE4.1", kernel_sse41);
+    }
+#endif
+
+#ifdef WITH_CYCLES_OPTIMIZED_KERNEL_SSE3
+    if (DebugFlags().cpu.has_sse3() && system_cpu_support_sse3()) {
+      return KernelInfo("SSE3", kernel_sse3);
+    }
+#endif
+
+#ifdef WITH_CYCLES_OPTIMIZED_KERNEL_SSE2
+    if (DebugFlags().cpu.has_sse2() && system_cpu_support_sse2()) {
+      return KernelInfo("SSE2", kernel_sse2);
+    }
+#endif
+
+    return KernelInfo("default", kernel_default);
+  }
+
+  KernelInfo kernel_info_;
+};
+
+CCL_NAMESPACE_END