Author: Shilei Tian Date: 2025-04-14T11:52:19-04:00 New Revision: fcf0f810ac4b22bda3f21048784ee114da1cb061
URL: https://github.com/llvm/llvm-project/commit/fcf0f810ac4b22bda3f21048784ee114da1cb061 DIFF: https://github.com/llvm/llvm-project/commit/fcf0f810ac4b22bda3f21048784ee114da1cb061.diff LOG: [Clang][AMDGPU] Enable `avail-extern-to-local` for ThinLTO in HIP (#134476) In HIP, the Clang driver already sets `force-import-all` when ThinLTO is enabled. As a result, all imported functions get the `available_externally` linkage. However, these functions are later removed by the `EliminateAvailableExternallyPass`, effectively undoing the forced import and eventually leading to link errors. The `EliminateAvailableExternallyPass` provides an option to convert `available_externally` functions into local functions, renaming them to avoid conflicts. This behavior is exactly what we need for HIP. This PR enables that option (`avail-extern-to-local`) alongside `force-import-all` when ThinLTO is used. With this change, ThinLTO almost works correctly on AMDGPU. The only remaining issue is an undefined reference to `__assert_fail`, but that falls outside the scope of this PR. Added: clang/test/Driver/hip-thinlto.hip Modified: clang/lib/Driver/ToolChains/HIPAMD.cpp Removed: ################################################################################ diff --git a/clang/lib/Driver/ToolChains/HIPAMD.cpp b/clang/lib/Driver/ToolChains/HIPAMD.cpp index 52b8a4510792f..4419339720b87 100644 --- a/clang/lib/Driver/ToolChains/HIPAMD.cpp +++ b/clang/lib/Driver/ToolChains/HIPAMD.cpp @@ -103,8 +103,10 @@ void AMDGCN::Linker::constructLldCommand(Compilation &C, const JobAction &JA, // ToDo: Remove this option after AMDGPU backend supports ISA-level linking. // Since AMDGPU backend currently does not support ISA-level linking, all // called functions need to be imported. - if (IsThinLTO) + if (IsThinLTO) { LldArgs.push_back(Args.MakeArgString("-plugin-opt=-force-import-all")); + LldArgs.push_back(Args.MakeArgString("-plugin-opt=-avail-extern-to-local")); + } for (const Arg *A : Args.filtered(options::OPT_mllvm)) { LldArgs.push_back( diff --git a/clang/test/Driver/hip-thinlto.hip b/clang/test/Driver/hip-thinlto.hip new file mode 100644 index 0000000000000..4227cd3f2e9f9 --- /dev/null +++ b/clang/test/Driver/hip-thinlto.hip @@ -0,0 +1,8 @@ +// RUN: %clang -foffload-lto=thin -nogpulib -nogpuinc %s -### 2>&1 | FileCheck %s + +// CHECK: -plugin-opt=thinlto +// CHECK-SAME: -plugin-opt=-force-import-all +// CHECK-SAME: -plugin-opt=-avail-extern-to-local +int main(int, char *[]) { + return 0; +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
