[llvm-dev] Ninja hangs when I try to build

[Alexandre Ganea via llvm-dev]

I think the linker message occurs because Paul is compiling a 32-bit target (x86). When the 32-bit linker is out-of-space it automatically falls back to the 64-bit linker (x64), thus the message.

Paul, there are several options here. You could perhaps use the 64-bit target instead? Such as:

> mkdir buildVS && cd buildVS
>  cmake -G"Visual Studio 16 2019" -Thost=x64 ../llvm (your other cmake options)

The default scenario you’re seeing is `cl.exe` using /Zi which offloads the PDB generation to `mspdbsrv.exe`. Since the LLVM libs are quite big, something in there might be running out of memory in a 32-bit process. You should be fine if switching to 64-bit host processes.


Another option is to build with Clang instead of MSVC in which case /Zi is like /Z7.
There’s already LLVM 10.0 embedded into Visual Studio (ensure it is installed through the VS Installer, click Modify):

> cmake -G "Visual Studio 16 2019" -TClangCL ../llvm (your other cmake options)

Or download & install the LLVM 11.0 release (and install the “llvm2019” extension in Visual Studio: Extensions menu, Manage Extensions, click “Online” on the left, and use the search box):

> cmake -G "Visual Studio 16 2019" -Tllvm ../llvm (your other cmake options)


Another other option is to create a secondary build folder and use ninja for building, and VS for editing & debugging. This is the best in terms of iteration times I would say.
To use MSVC & Ninja you would do:

> mkdir buildninja && cd buildninja
> cmake -G Ninja ../llvm -DCMAKE_BUILD_TYPE=Debug -DLLVM_OPTIMIZED_TABLEGEN=ON -DLLVM_ENABLE_PROJECTS="clang;lld;llvm"  -DLLVM_ENABLE_ASSERTIONS=ON -DLLVM_ENABLE_LIBXML2=OFF
> ninja check-all

Or if you want to use LLVM 11.0 & Ninja:

> cmake -G Ninja ../llvm -DCMAKE_BUILD_TYPE=Debug -DLLVM_OPTIMIZED_TABLEGEN=ON -DCMAKE_C_COMPILER=”C:/Program Files/LLVM/bin/clang-cl.exe” -DCMAKE_CXX_COMPILER=”C:/Program Files/LLVM/bin/clang-cl.exe” -DCMAKE_LINKER=”C:/Program Files/LLVM/bin/lld-link.exe” -DLLVM_ENABLE_PROJECTS="clang;lld;llvm"  -DLLVM_ENABLE_ASSERTIONS=ON -DLLVM_ENABLE_LIBXML2=OFF

Important - ensure all the above commands run in a Visual Studio cmd prompt, by first launching “x64 Native Tools Command Prompt for VS 2019” from your start menu.

Alex.

De : llvm-dev <llvm-dev-bounces at lists.llvm.org> De la part de Adrian McCarthy via llvm-dev
Envoyé : December 8, 2020 5:14 PM
À : Paul C. Anagnostopoulos <paul at windfall.com>
Cc : llvm-dev <llvm-dev at lists.llvm.org>
Objet : Re: [llvm-dev] Ninja hangs when I try to build

Sorry, I'm not familiar with "the usual message about switching from the 32-bit to the 64-bit linker."  Can you elaborate?

> Is there an easy way to turn off PDB creation?

Probably, but I don't know it offhand.  The MS linker is going to produce a PDB by default if /DEBUG is specified, and it's pretty common to generate them for "release" builds as well.

My guess is that you're building multiple configurations at once, and different configurations (e.g., 32- and 64-bit, or debug and release) are trying to write their own PDBs to the same file name.  I generally only build one configuration at a time, and I use ninja (even with MSVC) rather than the Visual Studio solution.  Off the top of my head, exactly where the Cmake-generated build configurations try to place the PDBs.

On Tue, Dec 8, 2020 at 1:17 PM Paul C. Anagnostopoulos <paul at windfall.com<mailto:paul at windfall.com>> wrote:
Thank you! I killed mspdbsrv and things got much further. Now I'm getting the usual message about switching from the 32-bit to the 64-bit linker, and then an "Unexpected PDB error; RPC (23)" message. This has been going on for awhile.

Is there an easy way to turn off PDB creation?

At 12/8/2020 02:17 PM, Adrian McCarthy wrote:
>The program database manager is a separate process VS uses to compile debug info into a PDB.  The error happens when it's trying to update a PDB that was created (or last modified) by a newer version of the PDB manager.
>
><https://docs.microsoft.com/en-us/cpp/error-messages/compiler-errors-1/fatal-error-c1902?view=msvc-160>https://docs.microsoft.com/en-us/cpp/error-messages/compiler-errors-1/fatal-error-c1902?view=msvc-160
>
>I suspect you have more than one version of VS installed.
>
>I would close all instances of Visual Studio, check your environment to ensure that your build is set up to use the specific version you're expecting, and make sure there are no lingering processes running mspdbsrv.exe, and then try again.  If the problem recurs after that, I'd repeat but also delete the PDB files in question and force the compiler to rebuild them from scratch.
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