[cfe-dev] [llvm-dev] Proper way to build LLVM+Clang

[Neil Nelson via cfe-dev]

Very good.

In the CMakeLists.txt file showing the error is the line

set(LIBC_TARGET_OS ${CMAKE_SYSTEM_NAME})

where below that line LIBC_TARGET_OS is put into the directory string 
giving the error such that CMAKE_SYSTEM_NAME is set to 'darwin' (note 
the lower case change in the code) by most likely a calling makefile.

in the llvm-project directory the following line

grep -r CMAKE_SYSTEM_NAME *

gives close to 200 lines mostly in makefiles. Looking down that list it 
is interesting to see that the sub-projects to llvm-project have a 
variety of ways to use the CMAKE_SYSTEM_NAME string. It is not regular 
in the sub-projects. Some distinctions are by OS and others by hardware, 
x86_64 and aarch64, with aarch64 identifying ARM processors. But 
apparently you have an x86_64 processor.

We do not have the darwin directory for the files but we have files with 
the same name in what would be a closely related directory and that 
those two related directories are based on processor type. We might try 
an experiment, work an hypothesis. Let's create the needed darwin 
directory and copy the two files in from the x86_64 directory and then 
run the build sequence and see what happens.

If the build fails or the resulting build does not run as expected, we 
know that the two files on hand from the linux directory will not work 
and someone will need to construct those files and make them available, 
which may take a while.

But if the build is successful, then we have identified an easily 
correctable bug in the makefiles and you are making headway.

Neil Nelson

On 7/26/20 5:05 PM, Aditya Atluri wrote:
> There are only files for linux (x86_64 and aarch64) there. Don't know 
> why there are no files for darwin. May be a libc developer care to answer?
>
> On Sun, Jul 26, 2020 at 12:47 AM Neil Nelson via cfe-dev 
> <cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> wrote:
>
>     On Ubuntu 20.04 I have both those files in the directory
>
>     ~/llvm-project/libc/config/linux/x86_64
>
>     Will the following command work in the directory ~/llvm-project/libc?
>
>     find . -name headers.txt
>
>     Neil Nelson
>
>     On 7/25/20 10:52 PM, Aditya Atluri via cfe-dev wrote:
>>     Not so much actually, I am seeing build error for libc on MacOS
>>     Mojave
>>
>>     CMake Error at
>>     /Users/aditya/Code/github/llvm_src/llvm-project/libc/CMakeLists.txt:72
>>     (include):
>>
>>     include could not find load file:
>>
>>
>>     /Users/aditya/Code/github/llvm_src/llvm-project/libc/config/darwin/x86_64/entrypoints.txt
>>
>>
>>
>>     CMake Error at
>>     /Users/aditya/Code/github/llvm_src/llvm-project/libc/CMakeLists.txt:73
>>     (include):
>>
>>     include could not find load file:
>>
>>
>>     /Users/aditya/Code/github/llvm_src/llvm-project/libc/config/darwin/x86_64/headers.txt
>>
>>
>>
>>     -- Skipping libc entrypoint libc.src.assert.__assert_fail.
>>
>>     -- Skipping libc entrypoint libc.src.errno.__errno_location.
>>
>>     -- Skipping libc entrypoint libc.src.math.cosf.
>>
>>     -- Skipping libc entrypoint libc.src.math.sinf.
>>
>>     -- Skipping libc entrypoint libc.src.math.sincosf.
>>
>>
>>
>>
>>     On Tue, Jul 7, 2020 at 5:16 PM Dobby HouseElf
>>     <dobby.thefreeelf at yahoo.com <mailto:dobby.thefreeelf at yahoo.com>>
>>     wrote:
>>
>>         Hello,
>>
>>         Are you trying to build LLVM from GitHub source
>>         (https://github.com/llvm/llvm-project)?
>>         The README.md describes the build steps pretty clearly.
>>
>>         On Linux, I use:
>>         $ cd llvm-project
>>          $ mkdir build
>>          $ cd build
>>          $ cmake "Unix Makefiles" -DLLVM_ENABLE_PROJECTS=clang ../llvm
>>          $ make
>>
>>         Hope that helps!
>>
>>         -----------------------------------------------------------------------------------------------------------------------------
>>         From:llvm-dev <llvm-dev-bounces at lists.llvm.org
>>         <mailto:llvm-dev-bounces at lists.llvm.org>> *On Behalf Of
>>         *Aditya Atluri via llvm-dev
>>         *Sent:* Friday, July 3, 2020 9:04 AM
>>         *To:* LLVM Dev <llvm-dev at lists.llvm.org
>>         <mailto:llvm-dev at lists.llvm.org>>; cfe-dev at lists.llvm.org
>>         <mailto:cfe-dev at lists.llvm.org>
>>         *Subject:* [llvm-dev] Proper way to build LLVM+Clang
>>         *Sent:* Friday, July 3, 2020 9:04 AM
>>         *To:* LLVM Dev <llvm-dev at lists.llvm.org
>>         <mailto:llvm-dev at lists.llvm.org>>; cfe-dev at lists.llvm.org
>>         <mailto:cfe-dev at lists.llvm.org>
>>         *Subject:* [llvm-dev] Proper way to build LLVM+Clang
>>
>>         Hi,
>>
>>         I couldn't find a decent guide to build llvm+clang and all
>>         the other projects after moving to llvm-project. I am
>>         checking with you to know how you are building
>>         llvm+clang+projects
>>
>>         Thank you!
>>
>>
>>
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