feat: Small optimization in toradix (#8040)

Avoid doing pointer math on every iteration, instead loop from the pointer directly
AztecProtocol · Aug 16, 2024 · 0dc7a50 · 0dc7a50
1 parent 047461a
commit 0dc7a50
Showing 1 changed file with 28 additions and 19 deletions.
diff --git a/noir/noir-repo/compiler/noirc_evaluator/src/brillig/brillig_ir/codegen_intrinsic.rs b/noir/noir-repo/compiler/noirc_evaluator/src/brillig/brillig_ir/codegen_intrinsic.rs
@@ -84,28 +84,37 @@ impl<F: AcirField + DebugToString> BrilligContext<F> {
             output: HeapArray { pointer: target_vector.pointer, size: limb_count },
         });
 
-        let limb_field = SingleAddrVariable::new(self.allocate_register(), F::max_num_bits());
-        let limb_casted = SingleAddrVariable::new(self.allocate_register(), limb_bit_size);
-
         if limb_bit_size != F::max_num_bits() {
-            self.codegen_loop(target_vector.size, |ctx, iterator_register| {
-                // Read the limb
-                ctx.codegen_array_get(target_vector.pointer, iterator_register, limb_field.address);
-                // Cast it
-                ctx.cast_instruction(limb_casted, limb_field);
-                // Write it
-                ctx.codegen_array_set(
-                    target_vector.pointer,
-                    iterator_register,
-                    limb_casted.address,
-                );
-            });
+            let end_pointer = self.allocate_register();
+            let temporary_register = self.allocate_register();
+
+            self.memory_op_instruction(
+                target_vector.pointer,
+                target_vector.size,
+                end_pointer,
+                BrilligBinaryOp::Add,
+            );
+
+            self.codegen_for_loop(
+                Some(target_vector.pointer),
+                end_pointer,
+                None,
+                |ctx, item_pointer| {
+                    ctx.load_instruction(temporary_register, item_pointer.address);
+
+                    ctx.cast(
+                        SingleAddrVariable::new(temporary_register, limb_bit_size),
+                        SingleAddrVariable::new(temporary_register, F::max_num_bits()),
+                    );
+
+                    ctx.store_instruction(item_pointer.address, temporary_register);
+                },
+            );
+
+            self.deallocate_register(end_pointer);
+            self.deallocate_register(temporary_register);
         }
 
-        // Deallocate our temporary registers
-        self.deallocate_single_addr(limb_field);
-        self.deallocate_single_addr(limb_casted);
-
         if big_endian {
             self.codegen_reverse_vector_in_place(target_vector);
         }