Optimize performance of depthwise_conv_bwd

[ZzSean]

PR types

Performance optimization

PR changes

OPs

Describe

Optimize performance of depthwise_conv_bwd for input

• Method:

1. Reduce modulo calculations and other redundant calculations
2. Modify the config of block/grid

• Result:

config	pytorch	paddle dev	paddle this PR	speedup
input[2048, 1024, 4, 4] filter[1024, 1, 4, 4] stride=1 pad=0 dilation=1	1.1070ms	2.9660ms	1.0798ms	2.75x

[paddle-bot[bot]]

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