llvm dev - Feb 2019 - error building LLVM opt tool under Cygwin

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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> -----Original Message-----
> From: llvm-dev <llvm-dev-bounces at lists.llvm.org> On Behalf Of s n
via llvm-dev
> Sent: Wednesday, February 27, 2019 9:31 PM
> To: llvm-dev at lists.llvm.org
> Subject: [EXT] [llvm-dev] error building LLVM opt tool under Cygwin
> 
> 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?
"Exec format error" means the file is corrupted, or not an executable.
Not sure how you would get that result without the build producing some sort of
error message.  You could try "file opt.exe" to rule out the
possibility that it's something that isn't an executable.  Maybe try
cleaning and rebuilding.  Also, use a verbose build ("make VERBOSE=1"
or "ninja -v") to see the command that actually produces opt.exe.

In general, Cygwin is not well tested; if you can, I'd recommend using mingw
or Visual Studio instead.
> 
> 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"
The correct option is "-DCMAKE_INSTALL_PREFIX=..."; like you would
expect, it's supposed to set the install prefix.

-Eli

On Thu, Feb 28, 2019 at 3:15 PM Eli Friedman via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> > -----Original Message-----
> > From: llvm-dev <llvm-dev-bounces at lists.llvm.org> On Behalf Of
s n via
> llvm-dev
> > Sent: Wednesday, February 27, 2019 9:31 PM
> > To: llvm-dev at lists.llvm.org
> > Subject: [EXT] [llvm-dev] error building LLVM opt tool under Cygwin
> >
> > 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?
>
> "Exec format error" means the file is corrupted, or not an
executable.
> Not sure how you would get that result without the build producing some
> sort of error message.  You could try "file opt.exe" to rule out
the
> possibility that it's something that isn't an executable.  Maybe
try
> cleaning and rebuilding.  Also, use a verbose build ("make
VERBOSE=1" or
> "ninja -v") to see the command that actually produces opt.exe.
>
When the disk is almost full, some tools create broken executable. I don't
know if this is the case though. (If that's the case, you need to delete
files to fix it.)

In general, Cygwin is not well tested; if you can, I'd recommend
using
> mingw or Visual Studio instead.
>
> >
> > 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"
>
> The correct option is "-DCMAKE_INSTALL_PREFIX=..."; like you
would expect,
> it's supposed to set the install prefix.
>
> -Eli
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
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