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// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
// Micro-benchmark for ffi struct field stores and loads.
//
// Only tests a single field because the FfiMemory benchmark already tests loads
// and stores of different field sizes.
import 'dart:ffi';
import 'package:ffi/ffi.dart';
import 'package:benchmark_harness/benchmark_harness.dart';
//
// Struct field store (plus Pointer elementAt and load).
//
void doStoreInt32(Pointer<VeryLargeStruct> pointer, int length) {
for (int i = 0; i < length; i++) {
pointer[i].c = 1;
}
}
//
// Struct field load (plus Pointer elementAt and load).
//
int doLoadInt32(Pointer<VeryLargeStruct> pointer, int length) {
int x = 0;
for (int i = 0; i < length; i++) {
x += pointer[i].c;
}
return x;
}
//
// Benchmark fixture.
//
// Number of repeats: 1000
// * CPU: Intel(R) Xeon(R) Gold 6154
// * Architecture: x64
// * 150000 - 465000 us (without optimizations)
// * 14 - ??? us (expected with optimizations, on par with typed data)
const N = 1000;
class FieldLoadStore extends BenchmarkBase {
Pointer<VeryLargeStruct> pointer = nullptr;
FieldLoadStore() : super('FfiStruct.FieldLoadStore');
@override
void setup() => pointer = allocate(count: N);
@override
void teardown() => free(pointer);
@override
void run() {
doStoreInt32(pointer, N);
final int x = doLoadInt32(pointer, N);
if (x != N) {
throw Exception('$name: Unexpected result: $x');
}
}
}
//
// Main driver.
//
void main() {
final benchmarks = [
() => FieldLoadStore(),
];
for (final benchmark in benchmarks) {
benchmark().report();
}
}
//
// Test struct.
//
class VeryLargeStruct extends Struct {
@Int8()
external int a;
@Int16()
external int b;
@Int32()
external int c;
@Int64()
external int d;
@Uint8()
external int e;
@Uint16()
external int f;
@Uint32()
external int g;
@Uint64()
external int h;
@IntPtr()
external int i;
@Double()
external double j;
@Float()
external double k;
external Pointer<VeryLargeStruct> parent;
@IntPtr()
external int numChildren;
external Pointer<VeryLargeStruct> children;
@Int8()
external int smallLastField;
}