[llvm-dev] What's LLVM{target}CodeGen vs {target}CodeGen?

[Robert Baruch via llvm-dev]

Thanks, that was it! Well-spotted!

--Rob


On Sun, Oct 15, 2017 at 6:17 PM Justin Bogner <mail at justinbogner.com> wrote:

> Robert Baruch via llvm-dev <llvm-dev at lists.llvm.org> writes:
> > Hi all,
> >
> > *TL;DR:* I have a target TMS9900CodeGen but cmake is looking for
> LLVMTMS9900
> > or LLVMTMS9900CodeGen which I don't have, and cmake dies. But the MSP430
> target
> > doesn't have that either, and cmake is happy with it. What am I missing?
> >
> > *The premise:*
> >
> > I may be making a huge mistake, but I'm trying to develop an LLVM
> backend.
> > I'm writing up some notes while I do so, and I hope to update the
> > documentation. However, I ran into a bit of a problem running cmake. Note
> > that I built the trunk release just fine, right now I'm modifying it.
> >
> > *The setup:*
> >
> > My target is called TMS9900 because I'm a masochist, and I'm just trying
> to
> > make a bare do-nothing skeleton to start with. I have this:
> >
> > lib/Target/TMS9900
> >   - CMakeLists.txt
> >   - LLVMBuild.txt
> >   - TMS9900TargetMachine.cpp
> >   - TMS9900TargetMachine.h
> >   - TMS9900.td
> >
> > TMS9900TargetMachine is the barest class I could make. It derives from
> > LLVMTargetMachine, and passes everything through (although it defines the
> > DataLayout).
> >
> > CMakeLists.txt is also pretty small:
> >
> > set(LLVM_TARGET_DEFINITIONS TMS9900.td)
> >
> > add_llvm_library(TMS9900CodeGen
> >   TMS9900TargetMachine.cpp
> >   )
>
> This should be add_llvm_target, rather than add_llvm_library. This does
> some extra work, including calling the target LLVMXYZ rather than just
> XYZ.
>
> > LLVMBuild.txt is as minimal as I could guess at:
> >
> > [common]
> > subdirectories =
> >
> > [component_0]
> > type = TargetGroup
> > name = TMS9900
> > parent = Target
> >
> > [component_1]
> > type = Library
> > name = TMS9900CodeGen
> > parent = TMS9900
> > required_libraries = Analysis AsmPrinter CodeGen Core MC Scalar
> > SelectionDAG Support Target TransformUtils
> > add_to_library_groups = TMS9900
> >
> > And finally, TMS9900.td contains:
> >
> > include "llvm/Target/Target.td"
> > def TMS9900 : Target { }
> >
> > I also updated lib/Target/LLVMBuild.txt's [common] subdirectories to
> > include TMS9900.
> >
> > *The punchline:*
> >
> > Now, I tried to run cmake:
> >
> > $ cd build
> > $ cmake -G "Unix Makefiles" -DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=TMS9900
> > ../llvm
> > ... stuff ...
> > CMake Error at cmake/modules/LLVM-Config.cmake:178 (message):
> >   Target TMS9900 is not in the set of libraries.
> > Call Stack (most recent call first):
> >   cmake/modules/AddLLVM.cmake:525 (llvm_map_components_to_libnames)
> >   cmake/modules/AddLLVM.cmake:574 (llvm_add_library)
> >   tools/lto/CMakeLists.txt:19 (add_llvm_library)
> >
> > (Line numbers may be off slightly, since I added some message() lines).
> So
> > I tracked this error down to where LLVM-Config.cmake is looking for
> targets
> > whose name, given {target}, is either LLVM{target} or
> LLVM{target}CodeGen.
> >
> > Of course, I have no such targets.
> >
> > The weird thing is that I looked at the MSP430 directory, and it does not
> > have LLVMMSP430 or LLVMMSP430CodeGen, either. It just has MSP430CodeGen
> yet
> > somehow that target works just fine.
> >
> > *What am I missing?*
> >
> > Thanks!
> >
> > --Rob
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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