[llvm-dev] error building LLVM opt tool under Cygwin

[s n via llvm-dev]

Hello, I downloaded and built llvm-7.0.1 as per the instructions on the 
website docs. It seems that I can run many of the tools in build/bin (eg 
llvm-diff or count etc) with the exception of opt where I get "-bash: 
./opt.exe: cannot execute binary file: Exec format error". I tried 
rebuilding just opt but still no luck. An ideas?

This is frustrating because opt is the tool I am most interested in, and 
the reason I built llvm at all instead of relying on the binary 
distribution.

On a somewhat unrelated note, what does make install actually do. I ran 
"cmake -DMAKE_INSTALL_PREFIX=..../llvm-project/install -P 
cmake_Install.cmake" and it ran for a long time, but I couldn't tell 
what it actually did. eg I couldn't see any directory called 
..../llvm=project/install"

thanks

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