Functions: move loops into function builders

This simplifies debugging, and can help improve performance
by making it easier for the compiler.

More optimization might still be possible by using `__restrict` in
a few places.

1 files changed, 33 insertions, 13 deletions

diff --git a/source/blender/functions/FN_multi_function_builder.hh b/source/blender/functions/FN_multi_function_builder.hh
index 7ba368d9a9d..2eaada5dea0 100644
--- a/source/blender/functions/FN_multi_function_builder.hh
+++ b/source/blender/functions/FN_multi_function_builder.hh
@@ -49,8 +49,11 @@ template<typename In1, typename Out1> class CustomMF_SI_SO : public MultiFunctio
     return [=](IndexMask mask, const VArray<In1> &in1, MutableSpan<Out1> out1) {
       /* Devirtualization results in a 2-3x speedup for some simple functions. */
       devirtualize_varray(in1, [&](const auto &in1) {
-        mask.foreach_index(
-            [&](int i) { new (static_cast<void *>(&out1[i])) Out1(element_fn(in1[i])); });
+        mask.to_best_mask_type([&](const auto &mask) {
+          for (const int64_t i : mask) {
+            new (static_cast<void *>(&out1[i])) Out1(element_fn(in1[i]));
+          }
+        });
       });
     };
   }
@@ -102,8 +105,11 @@ class CustomMF_SI_SI_SO : public MultiFunction {
                MutableSpan<Out1> out1) {
       /* Devirtualization results in a 2-3x speedup for some simple functions. */
       devirtualize_varray2(in1, in2, [&](const auto &in1, const auto &in2) {
-        mask.foreach_index(
-            [&](int i) { new (static_cast<void *>(&out1[i])) Out1(element_fn(in1[i], in2[i])); });
+        mask.to_best_mask_type([&](const auto &mask) {
+          for (const int64_t i : mask) {
+            new (static_cast<void *>(&out1[i])) Out1(element_fn(in1[i], in2[i]));
+          }
+        });
       });
     };
   }
@@ -160,9 +166,11 @@ class CustomMF_SI_SI_SI_SO : public MultiFunction {
                const VArray<In2> &in2,
                const VArray<In3> &in3,
                MutableSpan<Out1> out1) {
-      mask.foreach_index([&](int i) {
+      /* Virtual arrays are not devirtualized yet, to avoid generating lots of code without further
+       * consideration. */
+      for (const int64_t i : mask) {
         new (static_cast<void *>(&out1[i])) Out1(element_fn(in1[i], in2[i], in3[i]));
-      });
+      }
     };
   }
 
@@ -223,9 +231,11 @@ class CustomMF_SI_SI_SI_SI_SO : public MultiFunction {
                const VArray<In3> &in3,
                const VArray<In4> &in4,
                MutableSpan<Out1> out1) {
-      mask.foreach_index([&](int i) {
+      /* Virtual arrays are not devirtualized yet, to avoid generating lots of code without further
+       * consideration. */
+      for (const int64_t i : mask) {
         new (static_cast<void *>(&out1[i])) Out1(element_fn(in1[i], in2[i], in3[i], in4[i]));
-      });
+      }
     };
   }
 
@@ -268,7 +278,11 @@ template<typename Mut1> class CustomMF_SM : public MultiFunction {
   template<typename ElementFuncT> static FunctionT create_function(ElementFuncT element_fn)
   {
     return [=](IndexMask mask, MutableSpan<Mut1> mut1) {
-      mask.foreach_index([&](int i) { element_fn(mut1[i]); });
+      mask.to_best_mask_type([&](const auto &mask) {
+        for (const int64_t i : mask) {
+          element_fn(mut1[i]);
+        }
+      });
     };
   }
 
@@ -304,9 +318,11 @@ template<typename From, typename To> class CustomMF_Convert : public MultiFuncti
     const VArray<From> &inputs = params.readonly_single_input<From>(0);
     MutableSpan<To> outputs = params.uninitialized_single_output<To>(1);
 
-    for (int64_t i : mask) {
-      new (static_cast<void *>(&outputs[i])) To(inputs[i]);
-    }
+    mask.to_best_mask_type([&](const auto &mask) {
+      for (int64_t i : mask) {
+        new (static_cast<void *>(&outputs[i])) To(inputs[i]);
+      }
+    });
   }
 };
 
@@ -366,7 +382,11 @@ template<typename T> class CustomMF_Constant : public MultiFunction {
   void call(IndexMask mask, MFParams params, MFContext UNUSED(context)) const override
   {
     MutableSpan<T> output = params.uninitialized_single_output<T>(0);
-    mask.foreach_index([&](int i) { new (&output[i]) T(value_); });
+    mask.to_best_mask_type([&](const auto &mask) {
+      for (const int64_t i : mask) {
+        new (&output[i]) T(value_);
+      }
+    });
   }
 
   uint64_t hash() const override