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

[Niklas Söderlund]

Hi Jacopo,

Thanks for your patch.

On 2019-02-12 23:20:20 +0100, Jacopo Mondi wrote:
> 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>

Reviewed-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>

> ---
>  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
> 
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-- 
Regards,
Niklas Söderlund