error from install_github("wkopp/motifcounter")

[shouyongpeng]

Downloading GitHub repo wkopp/motifcounter@master
from URL https://api.github.com/repos/wkopp/motifcounter/zipball/master
Installing motifcounter
'/Library/Frameworks/R.framework/Resources/bin/R' --no-site-file --no-environ --no-save
--no-restore --quiet CMD INSTALL
'/private/var/folders/01/1xnkk3m530788bczxnbznbtr0000gp/T/RtmpR2z5H8/devtools14fe9237cab68/wkopp-motifcounter-87cfd05'
--library='/Library/Frameworks/R.framework/Versions/3.4/Resources/library' --install-tests

• installing source package ‘motifcounter’ ...
  ** libs
  clang -I/Library/Frameworks/R.framework/Resources/include -DNDEBUG -I/usr/local/include -fopenmp -DIN_R -fPIC -Wall -g -O2 -c Rbackground.c -o Rbackground.o
  clang: error: unsupported option '-fopenmp'
  make: *** [Rbackground.o] Error 1
  ERROR: compilation failed for package ‘motifcounter’
• removing ‘/Library/Frameworks/R.framework/Versions/3.4/Resources/library/motifcounter’
  Installation failed: Command failed (1)

[wkopp]

Apparently, clang does support openMP (https://clang.llvm.org/docs/UsersManual.html#openmp-features). Did you install a clang version with openMP support?

Also, could you try to install motifcounter from bioconductor directly using

source("https://bioconductor.org/biocLite.R")
biocLite("motifcounter")