Add benchmark for Lightmap::build()

Author: StephenCWills

test/CMakeLists.txt

@@ -59,6 +59,7 @@ set(benchmarks
   clx_render_benchmark
   crawl_benchmark
   dun_render_benchmark
+  light_render_benchmark
   palette_blending_benchmark
   path_benchmark
 )
@@ -106,6 +107,7 @@ target_link_dependencies(dun_render_benchmark PRIVATE libdevilutionx_so)
 target_link_dependencies(file_util_test PRIVATE libdevilutionx_file_util app_fatal_for_testing)
 target_link_dependencies(format_int_test PRIVATE libdevilutionx_format_int language_for_testing)
 target_link_dependencies(ini_test PRIVATE libdevilutionx_ini app_fatal_for_testing)
+target_link_dependencies(light_render_benchmark PRIVATE libdevilutionx_so)
 target_link_dependencies(palette_blending_test PRIVATE libdevilutionx_palette_blending DevilutionX::SDL libdevilutionx_strings GTest::gmock app_fatal_for_testing)
 target_link_dependencies(palette_blending_benchmark PRIVATE libdevilutionx_palette_blending DevilutionX::SDL app_fatal_for_testing)
 target_link_dependencies(parse_int_test PRIVATE libdevilutionx_parse_int)

test/fixtures/light_render_benchmark/dLight.dmp

@@ -0,0 +1,64 @@
+#include <cstddef>
+
+#include <benchmark/benchmark.h>
+
+#include "engine/render/light_render.hpp"
+#include "engine/surface.hpp"
+#include "lighting.h"
+#include "utils/log.hpp"
+#include "utils/paths.h"
+#include "utils/sdl_wrap.h"
+
+namespace devilution {
+namespace {
+
+void BM_BuildLightmap(benchmark::State &state)
+{
+	std::string benchmarkDataPath = paths::BasePath() + "test/fixtures/light_render_benchmark/dLight.dmp";
+	FILE *lightFile = std::fopen(benchmarkDataPath.c_str(), "rb");
+	if (lightFile != nullptr) {
+		std::fread(&dLight[0][0], sizeof(uint8_t), MAXDUNX * MAXDUNY, lightFile);
+		std::fclose(lightFile);
+	}
+
+	SDLSurfaceUniquePtr sdl_surface = SDLWrap::CreateRGBSurfaceWithFormat(
+	    /*flags=*/0, /*width=*/640, /*height=*/480, /*depth=*/8, SDL_PIXELFORMAT_INDEX8);
+	if (sdl_surface == nullptr) {
+		LogError("Failed to create SDL Surface: {}", SDL_GetError());
+		exit(1);
+	}
+	Surface out = Surface(sdl_surface.get());
+
+	Point tilePosition { 48, 44 };
+	Point targetBufferPosition { 0, -17 };
+	int viewportWidth = 640;
+	int viewportHeight = 352;
+	int rows = 25;
+	int columns = 10;
+	const uint8_t *outBuffer = out.at(0, 0);
+	uint16_t outPitch = out.pitch();
+	const uint8_t *lightTables = LightTables[0].data();
+	size_t lightTableSize = LightTables[0].size();
+
+	size_t numViewportTiles = rows * columns;
+	size_t numPixels = viewportWidth * viewportHeight;
+	size_t numBytesProcessed = 0;
+	size_t numItemsProcessed = 0;
+	for (auto _ : state) {
+		Lightmap lightmap = Lightmap::build(tilePosition, targetBufferPosition,
+		    viewportWidth, viewportHeight, rows, columns,
+		    outBuffer, outPitch, lightTables, lightTableSize);
+
+		uint8_t lightLevel = *lightmap.getLightingAt(outBuffer + outPitch * 120 + 120);
+		benchmark::DoNotOptimize(lightLevel);
+		numItemsProcessed += numViewportTiles;
+		numBytesProcessed += numPixels;
+	}
+	state.SetBytesProcessed(numBytesProcessed);
+	state.SetItemsProcessed(numItemsProcessed);
+}
+
+BENCHMARK(BM_BuildLightmap);
+
+} // namespace
+} // namespace devilution