[libcamera-devel] [PATCH 3/4] libcamera: device_enumerator: Remove move() on search() return

[Jacopo Mondi]

Remove the std::move() call on the shared_ptr<MediaDevice *> returned by
the search() method and remove the std::move() call on temporary return
value in pipeline handlers that use the method.

Thanks to copy elision, the regular constructor of the newly created
object is called, avoiding un-necessary copies.

Furthermore, the use of std::move() in the return and assignment
statements prevents the compiler from performing copy elision, forcing
it to generate two sequences of un-necessary calls to the class'
move constructor and destructor.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 src/libcamera/device_enumerator.cpp   | 2 +-
 src/libcamera/pipeline/ipu3/ipu3.cpp  | 4 ++--
 src/libcamera/pipeline/uvcvideo.cpp   | 2 +-
 src/libcamera/pipeline/vimc.cpp       | 2 +-
 test/v4l2_device/v4l2_device_test.cpp | 2 +-
 5 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/libcamera/device_enumerator.cpp b/src/libcamera/device_enumerator.cpp
index 03923b3bb457..7db40812906b 100644
--- a/src/libcamera/device_enumerator.cpp
+++ b/src/libcamera/device_enumerator.cpp
@@ -308,7 +308,7 @@ std::shared_ptr<MediaDevice> DeviceEnumerator::search(const DeviceMatch &dm)
 			LOG(DeviceEnumerator, Debug)
 				<< "Successful match for media device \""
 				<< media->driver() << "\"";
-			return std::move(media);
+			return media;
 		}
 	}
 
diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
index 34b03995ae31..f11e9cc61283 100644
--- a/src/libcamera/pipeline/ipu3/ipu3.cpp
+++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
@@ -279,11 +279,11 @@ bool PipelineHandlerIPU3::match(DeviceEnumerator *enumerator)
 	imgu_dm.add("ipu3-imgu 1 viewfinder");
 	imgu_dm.add("ipu3-imgu 1 3a stat");
 
-	cio2_ = std::move(enumerator->search(cio2_dm));
+	cio2_ = enumerator->search(cio2_dm);
 	if (!cio2_)
 		return false;
 
-	imgu_ = std::move(enumerator->search(imgu_dm));
+	imgu_ = enumerator->search(imgu_dm);
 	if (!imgu_)
 		return false;
 
diff --git a/src/libcamera/pipeline/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo.cpp
index fc31c52c0ecd..bf0d2fee3851 100644
--- a/src/libcamera/pipeline/uvcvideo.cpp
+++ b/src/libcamera/pipeline/uvcvideo.cpp
@@ -139,7 +139,7 @@ bool PipelineHandlerUVC::match(DeviceEnumerator *enumerator)
 {
 	DeviceMatch dm("uvcvideo");
 
-	media_ = std::move(enumerator->search(dm));
+	media_ = enumerator->search(dm);
 
 	if (!media_)
 		return false;
diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp
index 46840a4f4104..3aed24c3158a 100644
--- a/src/libcamera/pipeline/vimc.cpp
+++ b/src/libcamera/pipeline/vimc.cpp
@@ -148,7 +148,7 @@ bool PipelineHandlerVimc::match(DeviceEnumerator *enumerator)
 	dm.add("RGB/YUV Input");
 	dm.add("Scaler");
 
-	media_ = std::move(enumerator->search(dm));
+	media_ = enumerator->search(dm);
 	if (!media_)
 		return false;
 
diff --git a/test/v4l2_device/v4l2_device_test.cpp b/test/v4l2_device/v4l2_device_test.cpp
index 18d014caf4c8..76f2e55d8cb4 100644
--- a/test/v4l2_device/v4l2_device_test.cpp
+++ b/test/v4l2_device/v4l2_device_test.cpp
@@ -40,7 +40,7 @@ int V4L2DeviceTest::init()
 	}
 
 	DeviceMatch dm("uvcvideo");
-	media_ = std::move(enumerator_->search(dm));
+	media_ = enumerator_->search(dm);
 	if (!media_)
 		return TestSkip;
 
-- 
2.20.1