Author: Emery Conrad Date: 2026-07-10T08:28:32+03:00 New Revision: 3c138b5c5958dce2daefa923a1cae612e47a4273
URL: https://github.com/llvm/llvm-project/commit/3c138b5c5958dce2daefa923a1cae612e47a4273 DIFF: https://github.com/llvm/llvm-project/commit/3c138b5c5958dce2daefa923a1cae612e47a4273.diff LOG: Reland "[ORC] Track __emutls_t definitions in IRMaterializationUnit" (#207161) (#208413) Relands #207161, which was reverted in #207775 after the new `clang/test/Interpreter/emulated-tls.cpp` failed on Darwin with `Symbols not found: [ ___emutls_get_address ]`. The `IRMaterializationUnit` fix and the test are unchanged from #207161. What the failure exposed is that thread_locals never worked in clang-repl on Darwin: `__emutls_get_address` is implemented in the compiler-rt builtins static archive, and nothing links it into the process, so process-symbol lookup cannot resolve it (on Linux it resolves from `libgcc_s.so`). New in this reland, per @lhames's suggestion (option 2) on the original PR: - `clang/lib/Interpreter/IncrementalExecutor.cpp`: on `__APPLE__`, reference `__emutls_get_address` (forcing the builtins archive member to be linked in) and define it as an absolute symbol in the process-symbols JITDylib, following the precedent of the MinGW `__main` workaround in `lli.cpp`. Scoped to the default in-process JITBuilder path only — the host address would be meaningless for an out-of-process executor, and custom-builder clients do their own setup. Verified on an aarch64-darwin machine: the previously failing test now passes, along with the rest of `clang/test/Interpreter`. @vgvassilev @lhames — could you take a look? 🤖 Done with the help of [Claude Code](https://claude.com/claude-code) (Claude Opus 4.8, human in the loop) Co-authored-by: Emery Conrad <[email protected]> Added: clang/test/Interpreter/emulated-tls.cpp Modified: clang/lib/Interpreter/IncrementalExecutor.cpp llvm/lib/ExecutionEngine/Orc/Layer.cpp Removed: ################################################################################ diff --git a/clang/lib/Interpreter/IncrementalExecutor.cpp b/clang/lib/Interpreter/IncrementalExecutor.cpp index 65cb29a2f441a..8e64a3d73305e 100644 --- a/clang/lib/Interpreter/IncrementalExecutor.cpp +++ b/clang/lib/Interpreter/IncrementalExecutor.cpp @@ -27,6 +27,7 @@ #include "llvm/ADT/Twine.h" #include "llvm/ExecutionEngine/JITLink/JITLinkMemoryManager.h" +#include "llvm/ExecutionEngine/Orc/AbsoluteSymbols.h" #include "llvm/ExecutionEngine/Orc/Debugging/DebuggerSupport.h" #include "llvm/ExecutionEngine/Orc/EPCDynamicLibrarySearchGenerator.h" #include "llvm/ExecutionEngine/Orc/ExecutionUtils.h" @@ -60,6 +61,21 @@ #include <unistd.h> #endif +// Address of the host's emulated-TLS runtime entry point, or null if the host +// cannot provide one. On Darwin, __emutls_get_address lives in the compiler-rt +// builtins archive; referencing it here force-links the archive member into +// the binary. The reference must not exist elsewhere: MSVC has no emulated-TLS +// runtime (the link would fail), and ELF hosts resolve it from libgcc_s / +// compiler-rt through regular process-symbol lookup. +#ifdef __APPLE__ +extern "C" void *__emutls_get_address(void *); +static void *getEmuTLSGetAddressPtr() { + return reinterpret_cast<void *>(&__emutls_get_address); +} +#else +static void *getEmuTLSGetAddressPtr() { return nullptr; } +#endif + namespace clang { IncrementalExecutorBuilder::~IncrementalExecutorBuilder() = default; @@ -388,6 +404,29 @@ IncrementalExecutorBuilder::create(llvm::orc::ThreadSafeContext &TSC, if (!JB) return JB.takeError(); JITBuilder = std::move(*JB); + // TODO: Switch to native TLS on Darwin once clang-repl can adopt the ORC + // runtime (which provides __emutls_get_address and supports the full TLS + // lifecycle). That will also remove the in-process-only constraint below. + // + // For MachO targets, thread_locals are lowered to emulated TLS, but the + // runtime (__emutls_get_address) lives in the compiler-rt builtins archive + // and nothing else in this process references it, so it isn't linked in + // and process-symbol lookup cannot find it. Define the force-linked host + // symbol (see getEmuTLSGetAddressPtr) as an absolute symbol so it is + // visible to JIT'd code. In-process execution only: the address is + // meaningless in an out-of-process executor. + if (void *EmuTLSGetAddress = getEmuTLSGetAddressPtr(); + EmuTLSGetAddress && TT.isOSBinFormatMachO()) + JITBuilder->setNotifyCreatedCallback( + [EmuTLSGetAddress](llvm::orc::LLJIT &J) { + auto &JD = J.getProcessSymbolsJITDylib() + ? *J.getProcessSymbolsJITDylib() + : J.getMainJITDylib(); + return JD.define(llvm::orc::absoluteSymbols( + {{J.mangleAndIntern("__emutls_get_address"), + {llvm::orc::ExecutorAddr::fromPtr(EmuTLSGetAddress), + llvm::JITSymbolFlags::Exported}}})); + }); } llvm::Error Err = llvm::Error::success(); diff --git a/clang/test/Interpreter/emulated-tls.cpp b/clang/test/Interpreter/emulated-tls.cpp new file mode 100644 index 0000000000000..73afe172ef6d9 --- /dev/null +++ b/clang/test/Interpreter/emulated-tls.cpp @@ -0,0 +1,25 @@ +// REQUIRES: host-supports-jit +// UNSUPPORTED: system-windows +// +// An inline function that odr-uses a non-zero-initialized thread_local is +// emitted as a weak (linkonce_odr) definition into every PartialTranslationUnit +// that references it. With emulated TLS that set includes an __emutls_t.<var> +// symbol. When a later PTU re-defines the same weak set, ORC's +// IRMaterializationUnit::discard() must find each duplicated symbol in its +// SymbolToDefinition map. The emulated-TLS path used to register __emutls_t.<var> +// in SymbolFlags but not SymbolToDefinition, so discarding it dereferenced +// end() -- an assertion failure in +Asserts builds and heap corruption +// otherwise. Two PTUs each pulling in the same inline worker reproduces it. +// +// RUN: cat %s | clang-repl | FileCheck %s + +extern "C" int printf(const char *, ...); +template <int Tag> struct HeavyThing { static thread_local int tls; }; +template <int Tag> thread_local int HeavyThing<Tag>::tls = Tag + 1; +inline int worker() { return HeavyThing<1>::tls; } +int callA() { return worker(); } +int callB() { return worker(); } +auto r = printf("tls = %d, %d\n", callA(), callB()); +// CHECK: tls = 2, 2 + +%quit diff --git a/llvm/lib/ExecutionEngine/Orc/Layer.cpp b/llvm/lib/ExecutionEngine/Orc/Layer.cpp index eb144275da589..5e95b8c73b482 100644 --- a/llvm/lib/ExecutionEngine/Orc/Layer.cpp +++ b/llvm/lib/ExecutionEngine/Orc/Layer.cpp @@ -70,6 +70,7 @@ IRMaterializationUnit::IRMaterializationUnit( auto EmuTLST = Mangle(("__emutls_t." + GV.getName()).str()); SymbolFlags[EmuTLST] = Flags; + SymbolToDefinition[EmuTLST] = &GV; } continue; } _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
