Some performance optimizations (#5424)

* Some performance optimizations

This is globally removing some memory useless copy

* use a const ref return on std::string Settings::get to prevent data copy on getters which doesn't need to copy it
 * pass some stack created strings to static const as they are not modified anywhere
 * Camera: return nametags per const ref instead of a list pointer, we only need to read it
 * INodeDefManager: getAll should be a result ref writer instead of a return copy
 * INodeDefManager: getAlias should return a const std::string ref
 * Minimap: unroll a Scolor creation in blitMinimapPixersToImageRadar to prvent many variable construct/destruct which are unneeded (we rewrite the content in the loop)
 * CNodeDefManager::updateAliases: prevent a idef getall copy
 * Profiler: constness
 * rollback_interface: create real_name later, and use const ref
 * MapBlockMesh updateFastFaceRow: unroll TileSpec next_tile, which has a cost of 1.8% CPU due to variable allocation/destruction,
 * MapBlockMesh updateFastFaceRow: copy next_tile to tile only if it's a different tilespec
 * MapBlockMesh updateFastFaceRow: use memcpy to copy next_lights to lights to do it in a single cpu operation

2 files changed, 7 insertions, 7 deletions

diff --git a/src/client/clientlauncher.cpp b/src/client/clientlauncher.cpp
index 2adac53c2..bdd16205f 100644
--- a/src/client/clientlauncher.cpp
+++ b/src/client/clientlauncher.cpp
@@ -530,7 +530,7 @@ bool ClientLauncher::create_engine_device()
 
 	// Determine driver
 	video::E_DRIVER_TYPE driverType = video::EDT_OPENGL;
-	std::string driverstring = g_settings->get("video_driver");
+	const std::string &driverstring = g_settings->get("video_driver");
 	std::vector<video::E_DRIVER_TYPE> drivers
 		= porting::getSupportedVideoDrivers();
 	u32 i;
diff --git a/src/client/tile.cpp b/src/client/tile.cpp
index 000c766d0..85d388d6e 100644
--- a/src/client/tile.cpp
+++ b/src/client/tile.cpp
@@ -134,9 +134,8 @@ std::string getTexturePath(const std::string &filename)
 	/*
 		Check from texture_path
 	*/
-	std::string texture_path = g_settings->get("texture_path");
-	if (texture_path != "")
-	{
+	const std::string &texture_path = g_settings->get("texture_path");
+	if (texture_path != "") {
 		std::string testpath = texture_path + DIR_DELIM + filename;
 		// Check all filename extensions. Returns "" if not found.
 		fullpath = getImagePath(testpath);
@@ -1854,7 +1853,7 @@ bool TextureSource::generateImagePart(std::string part_of_name,
 			for (u32 x = 0; x < dim.Width; x++)
 			{
 				video::SColor c = baseimg->getPixel(x, y);
-				c.color ^= mask;	
+				c.color ^= mask;
 				baseimg->setPixel(x, y, c);
 			}
 		}
@@ -2266,7 +2265,8 @@ video::ITexture* TextureSource::getNormalTexture(const std::string &name)
 	if (isKnownSourceImage("override_normal.png"))
 		return getTexture("override_normal.png");
 	std::string fname_base = name;
-	std::string normal_ext = "_normal.png";
+	static const char *normal_ext = "_normal.png";
+	static const uint32_t normal_ext_size = strlen(normal_ext);
 	size_t pos = fname_base.find(".");
 	std::string fname_normal = fname_base.substr(0, pos) + normal_ext;
 	if (isKnownSourceImage(fname_normal)) {
@@ -2274,7 +2274,7 @@ video::ITexture* TextureSource::getNormalTexture(const std::string &name)
 		size_t i = 0;
 		while ((i = fname_base.find(".", i)) != std::string::npos) {
 			fname_base.replace(i, 4, normal_ext);
-			i += normal_ext.length();
+			i += normal_ext_size;
 		}
 		return getTexture(fname_base);
 		}