please document how llvm is expected to be built for linking

[matthiaskrgr]

Hi, I have my own setup of llvm/clang and enforce its use using CXX/CC flags.

When building osmesa-src I can see it finds directory where my custom llvm lives

        LLVM_CFLAGS:     -I/home/matthias/LLVM/LLVM_5_1/stage_2/build/include   -DLLVM_BUILD_GLOBAL_ISEL -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS
        LLVM_CXXFLAGS:   -I/home/matthias/LLVM/LLVM_5_1/stage_2/build/include -std=c++11 -fno-rtti -DLLVM_BUILD_GLOBAL_ISEL -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS
        LLVM_CPPFLAGS:   -I/home/matthias/LLVM/LLVM_5_1/stage_2/build/include   -DLLVM_BUILD_GLOBAL_ISEL -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS
        LLVM_LDFLAGS:    -L/home/matthias/LLVM/LLVM_5_1/stage_2/build/lib64 

but it fails linking against it

--- stderr
llvm-config: error: missing: /home/matthias/LLVM/LLVM_5_1/stage_2/build/lib64/libLLVMDemangle.so
llvm-config: error: missing: /home/matthias/LLVM/LLVM_5_1/stage_2/build/lib64/libLLVMSupport.so
llvm-config: error: missing: /home/matthias/LLVM/LLVM_5_1/stage_2/build/lib64/libLLVMBinaryFormat.so
llvm-config: error: missing: /home/matthias/LLVM/LLVM_5_1/stage_2/build/lib64/libLLVMCore.so
llvm-config: error: missing: /home/matthias/LLVM/LLVM_5_1/stage_2/build/lib64/libLLVMBitReader.so
llvm-config: error: missing: /home/matthias/LLVM/LLVM_5_1/stage_2/build/lib64/libLLVMMC.so
llvm-config: error: missing: /home/matthias/LLVM/LLVM_5_1/stage_2/build/lib64/libLLVMMCParser.so
llvm-config: error: missing: /home/matthias/LLVM/LLVM_5_1/stage_2/build/lib64/libLLVMObject.so
....

I tried building llvm with LLVM_BUILD_LLVM_DYLIB but that didn't help. https://llvm.org/docs/CMake.html

How does osmesa-src expect llvm to be compiled?

EDIT: also: what llvm versions are required/supported? travis uses 3.9 it seems, I am using 5.0.1.

[emilio]

I think LLVMCore and such should really be there. You could link statically with --disable-llvm-shared-libs, but that's usually not recommended.

You could pass down to configure, but I'd really try to figure out why your LLVM libraries are not built. On a local debug build of clang trunk I get libLLVMCore.so, for example.

There's extra docs on https://www.mesa3d.org/llvmpipe.html.

Any recent clang version >= 3.9 should be supported, modulo trunk which sometimes breaks (and thus needs a OsMesa update).

Sorry for the lag replying here, happy to help more if I can.

[matthiaskrgr]

I just tried the meson branch and it seems to build fine with that!

[peteasa]

Ref: https://llvm.org/docs/CMake.html

LLVM_BUILD_LLVM_DYLIB:BOOL -> all of LLVM’s components in a single shared library

BUILD_SHARED_LIBS -> each LLVM component is built as a shared library (only recommended for use by LLVM developers)

So to fix the build try building LLVM with BUILD_SHARED_LIBS configured!