Update LLVM from 14.0.6 to 21.1.2#8737
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csyonghe merged 13 commits intoshader-slang:masterfrom Oct 27, 2025
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This does not need to be permanent, as the build is cached on the CI.
samestep
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Oct 17, 2025
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Amazing, thank you for doing this! Someone who's more familiar with the code touched here should review this in more detail, but in particular, this would unblock any future efforts to reenable slang-llvm in Nixpkgs since LLVM versions 17 and older were dropped last month: NixOS/nixpkgs#440273 (comment)
I was able to successfully build this locally on x86 NixOS via the following commands in the flake dev shell:
git clean -xdfe .envrc
external/build-llvm.sh --source-dir build/slang-llvm_src --install-prefix build/slang-llvm_install
cmake --preset default --fresh -DSLANG_SLANG_LLVM_FLAVOR=USE_SYSTEM_LLVM -DLLVM_DIR=build/slang-llvm_install/lib/cmake/llvm -DClang_DIR=build/slang-llvm_install/lib/cmake/clang
cmake --build --preset release
csyonghe
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Oct 27, 2025
jvepsalainen-nv
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Nov 4, 2025
This PR upgrades slang-llvm to use LLVM 21.1.2. It also fixes the `USE_SYSTEM_LLVM` option on some Linux distributions (e.g. SUSE and derivatives) which don't ship separate components for LLVM or Clang, and instead just have `libLLVM.so` and `libclang-cpp.so` containing all components. ## Motivation I'm working on a [direct LLVM IR emitter](https://github.com/juliusikkala/slang/tree/llvm-target) for Slang. That work is in a fairly good state by now, but I still need to move the emitter into slang-llvm and link to LLVM in the Correct Way instead of whatever garbage I have in that branch right now. The problem with that is that slang-llvm currently links to a comparatively ancient LLVM version. There have been major changes to LLVM since then, and I wrote the emitter for LLVM 20-21. Differences between those two versions are minor and I can downgrade to 20 with little effort if that's better.
juliusikkala
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Nov 12, 2025
This PR upgrades slang-llvm to use LLVM 21.1.2. It also fixes the `USE_SYSTEM_LLVM` option on some Linux distributions (e.g. SUSE and derivatives) which don't ship separate components for LLVM or Clang, and instead just have `libLLVM.so` and `libclang-cpp.so` containing all components. ## Motivation I'm working on a [direct LLVM IR emitter](https://github.com/juliusikkala/slang/tree/llvm-target) for Slang. That work is in a fairly good state by now, but I still need to move the emitter into slang-llvm and link to LLVM in the Correct Way instead of whatever garbage I have in that branch right now. The problem with that is that slang-llvm currently links to a comparatively ancient LLVM version. There have been major changes to LLVM since then, and I wrote the emitter for LLVM 20-21. Differences between those two versions are minor and I can downgrade to 20 with little effort if that's better.
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This PR upgrades slang-llvm to use LLVM 21.1.2. It also fixes the
USE_SYSTEM_LLVMoption on some Linux distributions (e.g. SUSE and derivatives) which don't ship separate components for LLVM or Clang, and instead just havelibLLVM.soandlibclang-cpp.socontaining all components.Motivation
I'm working on a direct LLVM IR emitter for Slang. That work is in a fairly good state by now, but I still need to move the emitter into slang-llvm and link to LLVM in the Correct Way instead of whatever garbage I have in that branch right now. The problem with that is that slang-llvm currently links to a comparatively ancient LLVM version. There have been major changes to LLVM since then, and I wrote the emitter for LLVM 20-21. Differences between those two versions are minor and I can downgrade to 20 with little effort if that's better.