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

[Eli Friedman via llvm-dev]

(Comments inline.)

> -----Original Message-----
> From: s nedunuri <ss.nedunuri at gmail.com>
> Sent: Saturday, March 2, 2019 9:06 PM
> To: Rui Ueyama <ruiu at google.com>
> Cc: Eli Friedman <efriedma at quicinc.com>; llvm-dev <llvm-dev at lists.llvm.org>
> Subject: [EXT] Re: [llvm-dev] error building LLVM opt tool under Cygwin
> 
> Its very odd because a random selection of other generated executables seem
> to run just fine.  What about opt could cause problems with cygwin? I am
> running the executable from llvm-project/build/bin - I assume that's fine?

The only difference I can think of is that opt is substantially bigger that FileCheck etc.; a debug build with full debug info is on the order of gigabytes in size.  Maybe you're running into some implementation limit?  For example, if your disk is formatted as FAT32, or you're using 32-bit Cygwin, it might be impossible to emit an executable greater than 4GB.

You could try a release build instead as an experiment (-DCMAKE_BUILD_TYPE=Release).

> sorry that was a typo in transcribing. The actual text I typed was  "-
> DCMAKE_INSTALL_PREFIX=...". But I am still not clear what it actually does

It changes where "make install"/"ninja install" places the installed files.

-Eli