floret: Link with libatomic when 64-bit atomics need it

floret keeps its training token counter in a std::atomic<int64_t>. On riscv32 its operations become __atomic_*_8 libcalls, and floret is not linked with libatomic, so linking the CLI fails: ld.lld: error: undefined symbol: __atomic_fetch_add_8 Add a patch that checks in CMake whether 64-bit atomics need libatomic and only then links the libraries with it and adds it to floret.pc. AI-Generated: Uses Claude Code Signed-off-by: Khem Raj <khem.raj@oss.qualcomm.com>
2026-10-23 08:48:24 +00:00 · 2026-10-22 09:58:54 -07:00
1 parent c2a8b593f2
commit c8db06f46b
@@ -0,0 +1,77 @@
+From: Khem Raj <khem.raj@oss.qualcomm.com>
+Date: Wed, 21 Oct 2026 17:00:00 -0700
+Subject: [PATCH] cmake: Link with libatomic when 64-bit atomics need it
+
+FastText::tokenCount_ is a std::atomic<int64_t>. On 32-bit targets
+without 64-bit atomic instructions, such as riscv32, its operations
+become __atomic_*_8 libcalls, but floret is not linked with libatomic,
+so linking the floret CLI fails:
+
+  ld.lld: error: undefined symbol: __atomic_fetch_add_8
+  >>> referenced by fasttext.cc
+  >>>               fasttext.cc.o:(fasttext::FastText::trainThread(...)) in archive libfloret.a
+
+Check whether 64-bit atomics link on their own, and if not, whether
+they link with libatomic, and only in that case link the libraries with
+it, which also covers the CLI linking the static library, and add it to
+Libs.private in floret.pc. The test variable is global so the compiler
+cannot optimize the atomic operations away.
+
+Upstream-Status: Submitted [https://github.com/explosion/floret/pull/34]
+Signed-off-by: Khem Raj <khem.raj@oss.qualcomm.com>
+---
+ CMakeLists.txt | 27 +++++++++++++++++++++++++++
+ floret.pc.in   |  1 +
+ 2 files changed, 28 insertions(+)
+
+--- a/CMakeLists.txt
+++ b/CMakeLists.txt
+@@ -52,6 +52,29 @@
+     src/vector.cc)
+ 
+ 
+# std::atomic<int64_t> needs libatomic on 32-bit targets without 64-bit
+# atomic instructions, e.g. riscv32. The variable is global so the compiler
+# cannot optimize the atomic operations away.
+include(CheckCXXSourceCompiles)
+set(ATOMIC64_TEST "
+#include <atomic>
+#include <cstdint>
+std::atomic<int64_t> v;
+int main() {
+  v.fetch_add(1);
+  return static_cast<int>(v.load());
+}")
+check_cxx_source_compiles("${ATOMIC64_TEST}" HAVE_ATOMIC64)
+if (NOT HAVE_ATOMIC64)
+  set(CMAKE_REQUIRED_LIBRARIES atomic)
+  check_cxx_source_compiles("${ATOMIC64_TEST}" HAVE_ATOMIC64_WITH_LIBATOMIC)
+  unset(CMAKE_REQUIRED_LIBRARIES)
+  if (HAVE_ATOMIC64_WITH_LIBATOMIC)
+    set(ATOMIC_LIBRARY atomic)
+    set(PC_LIBS_PRIVATE "-latomic")
+  endif()
+endif()
+
+ if (NOT MSVC)
+   include(GNUInstallDirs)
+   configure_file("floret.pc.in" "floret.pc" @ONLY)
+@@ -66,6 +89,10 @@
+ set_target_properties(floret-static PROPERTIES OUTPUT_NAME floret)
+ set_target_properties(floret-static_pic PROPERTIES OUTPUT_NAME floret_pic
+   POSITION_INDEPENDENT_CODE True)
+target_link_libraries(floret-shared ${ATOMIC_LIBRARY})
+target_link_libraries(floret-static ${ATOMIC_LIBRARY})
+target_link_libraries(floret-static_pic ${ATOMIC_LIBRARY})
+
+ add_executable(floret-bin src/main.cc)
+ target_link_libraries(floret-bin pthread floret-static)
+ set_target_properties(floret-bin PROPERTIES PUBLIC_HEADER "${HEADER_FILES}" OUTPUT_NAME floret)
+--- a/floret.pc.in
+++ b/floret.pc.in
+@@ -7,4 +7,5 @@
+ Description: Efficient learning of word representations and sentence classification
+ Version: @PROJECT_VERSION@
+ Libs: -L${libdir} -lfloret
+Libs.private: @PC_LIBS_PRIVATE@
+ Cflags: -I${includedir}
@@ -18,6 +18,7 @@ DEPENDS = "zlib"
 SRC_URI = "git://github.com/explosion/floret.git;protocol=https;branch=main;tag=v${PV} \
           file://0001-PATCH-floret-Adjust-CMake-flags-for-cross-compilation.patch \
           file://0002-args.h-add-missing-cstdint-include-for-int64_t.patch \
+           file://0003-cmake-Link-with-libatomic-when-64-bit-atomics-need-i.patch \
           "

 SRCREV = "775638223bee4fabc420cc8234632557452558e0"