speed up autodiff

[codecov[bot]]

Codecov Report

Merging #397 (7244c52) into master (15eb406) will increase coverage by 0.15%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #397      +/-   ##
==========================================
+ Coverage   89.16%   89.32%   +0.15%     
==========================================
  Files          73       73              
  Lines        4449     4449              
==========================================
+ Hits         3967     3974       +7     
+ Misses        482      475       -7     

Impacted Files	Coverage Δ
lib/YaoBlocks/src/autodiff/apply_back.jl	96.22% <100.00%> (-0.95%)	:arrow_down:
lib/YaoBlocks/src/autodiff/adjroutines.jl	63.63% <0.00%> (+14.54%)	:arrow_up:

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[Roger-luo]

tests fail, need to fix the tests

[GiggleLiu]

@Roger-luo fixed.