Refactor conv 3 #5706

Job	Run time
apple (aarch64-apple-ios)	2m 24s
apple (aarch64-apple-darwin)	10m 45s
linux (raspbian)	7m 9s
linux (aarch64-unknown-linux-gnu)	12m 29s
linux (armv6vfp-unknown-linux-gnueabihf)	10m 22s
linux (armv7-unknown-linux-gnueabihf)	10m 12s
linux (aarch64-unknown-linux-musl)	12m 36s
linux (armv7-unknown-linux-musl)	10m 52s
linux (aarch64-linux-android)	1m 45s
linux (armv7-linux-androideabi)	1m 2s
linux (i686-linux-android)	2m 3s
linux (x86_64-linux-android)	1m 23s
linux (wasm32-unknown-unknown)	30s
linux (wasm32-wasi)	27s
	1h 23m 59s

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