Inliner section safety #3

AdamGlass · 2025-06-24T20:16:57Z

Alter LLVM behavior so that in MSVC environment, it follows MSVC inlining rules.

Currently there is no switch to enable/disable this functionality and it should operate for Rust as well.

The function already exposes a work list to avoid deep recursion, this commit starts utilizing it in a helper that could also lead to a deep recursion. We have observed this crash on `clang/test/C/C99/n590.c` with our internal builds that enable aggressive optimizations and hit the limit earlier than default release builds of Clang. See the added test for an example with a deeper recursion that used to crash in upstream Clang before this change with the following stack trace: ``` #0 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) /usr/local/google/home/ibiryukov/code/llvm-project/llvm/lib/Support/Unix/Signals.inc:804:13 #1 llvm::sys::RunSignalHandlers() /usr/local/google/home/ibiryukov/code/llvm-project/llvm/lib/Support/Signals.cpp:106:18 #2 SignalHandler(int, siginfo_t*, void*) /usr/local/google/home/ibiryukov/code/llvm-project/llvm/lib/Support/Unix/Signals.inc:0:3 #3 (/lib/x86_64-linux-gnu/libc.so.6+0x3fdf0) llvm#4 AnalyzeImplicitConversions(clang::Sema&, clang::Expr*, clang::SourceLocation, bool) /usr/local/google/home/ibiryukov/code/llvm-project/clang/lib/Sema/SemaChecking.cpp:12772:0 llvm#5 CheckCommaOperand /usr/local/google/home/ibiryukov/code/llvm-project/clang/lib/Sema/SemaChecking.cpp:0:3 llvm#6 AnalyzeImplicitConversions /usr/local/google/home/ibiryukov/code/llvm-project/clang/lib/Sema/SemaChecking.cpp:12644:7 llvm#7 AnalyzeImplicitConversions(clang::Sema&, clang::Expr*, clang::SourceLocation, bool) /usr/local/google/home/ibiryukov/code/llvm-project/clang/lib/Sema/SemaChecking.cpp:12776:5 llvm#8 CheckCommaOperand /usr/local/google/home/ibiryukov/code/llvm-project/clang/lib/Sema/SemaChecking.cpp:0:3 llvm#9 AnalyzeImplicitConversions /usr/local/google/home/ibiryukov/code/llvm-project/clang/lib/Sema/SemaChecking.cpp:12644:7 llvm#10 AnalyzeImplicitConversions(clang::Sema&, clang::Expr*, clang::SourceLocation, bool) /usr/local/google/home/ibiryukov/code/llvm-project/clang/lib/Sema/SemaChecking.cpp:12776:5 llvm#11 CheckCommaOperand /usr/local/google/home/ibiryukov/code/llvm-project/clang/lib/Sema/SemaChecking.cpp:0:3 llvm#12 AnalyzeImplicitConversions /usr/local/google/home/ibiryukov/code/llvm-project/clang/lib/Sema/SemaChecking.cpp:12644:7 llvm#13 AnalyzeImplicitConversions(clang::Sema&, clang::Expr*, clang::SourceLocation, bool) /usr/local/google/home/ibiryukov/code/llvm-project/clang/lib/Sema/SemaChecking.cpp:12776:5 llvm#14 CheckCommaOperand /usr/local/google/home/ibiryukov/code/llvm-project/clang/lib/Sema/SemaChecking.cpp:0:3 llvm#15 AnalyzeImplicitConversions /usr/local/google/home/ibiryukov/code/llvm-project/clang/lib/Sema/SemaChecking.cpp:12644:7 llvm#16 AnalyzeImplicitConversions(clang::Sema&, clang::Expr*, clang::SourceLocation, bool) /usr/local/google/home/ibiryukov/code/llvm-project/clang/lib/Sema/SemaChecking.cpp:12776:5 llvm#17 CheckCommaOperand /usr/local/google/home/ibiryukov/code/llvm-project/clang/lib/Sema/SemaChecking.cpp:0:3 llvm#18 AnalyzeImplicitConversions /usr/local/google/home/ibiryukov/code/llvm-project/clang/lib/Sema/SemaChecking.cpp:12644:7 llvm#19 AnalyzeImplicitConversions(clang::Sema&, clang::Expr*, clang::SourceLocation, bool) /usr/local/google/home/ibiryukov/code/llvm-project/clang/lib/Sema/SemaChecking.cpp:12776:5 ... 700+ more stack frames. ```

`clang-repl --cuda` was previously crashing with a segmentation fault, instead of reporting a clean error ``` (base) anutosh491@Anutoshs-MacBook-Air bin % ./clang-repl --cuda #0 0x0000000111da4fbc llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/local/libexec/llvm-20/lib/libLLVM.dylib+0x150fbc) #1 0x0000000111da31dc llvm::sys::RunSignalHandlers() (/opt/local/libexec/llvm-20/lib/libLLVM.dylib+0x14f1dc) #2 0x0000000111da5628 SignalHandler(int) (/opt/local/libexec/llvm-20/lib/libLLVM.dylib+0x151628) #3 0x000000019b242de4 (/usr/lib/system/libsystem_platform.dylib+0x180482de4) llvm#4 0x0000000107f638d0 clang::IncrementalCUDADeviceParser::IncrementalCUDADeviceParser(std::__1::unique_ptr<clang::CompilerInstance, std::__1::default_delete<clang::CompilerInstance>>, clang::CompilerInstance&, llvm::IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem>, llvm::Error&, std::__1::list<clang::PartialTranslationUnit, std::__1::allocator<clang::PartialTranslationUnit>> const&) (/opt/local/libexec/llvm-20/lib/libclang-cpp.dylib+0x216b8d0) llvm#5 0x0000000107f638d0 clang::IncrementalCUDADeviceParser::IncrementalCUDADeviceParser(std::__1::unique_ptr<clang::CompilerInstance, std::__1::default_delete<clang::CompilerInstance>>, clang::CompilerInstance&, llvm::IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem>, llvm::Error&, std::__1::list<clang::PartialTranslationUnit, std::__1::allocator<clang::PartialTranslationUnit>> const&) (/opt/local/libexec/llvm-20/lib/libclang-cpp.dylib+0x216b8d0) llvm#6 0x0000000107f6bac8 clang::Interpreter::createWithCUDA(std::__1::unique_ptr<clang::CompilerInstance, std::__1::default_delete<clang::CompilerInstance>>, std::__1::unique_ptr<clang::CompilerInstance, std::__1::default_delete<clang::CompilerInstance>>) (/opt/local/libexec/llvm-20/lib/libclang-cpp.dylib+0x2173ac8) llvm#7 0x000000010206f8a8 main (/opt/local/libexec/llvm-20/bin/clang-repl+0x1000038a8) llvm#8 0x000000019ae8c274 Segmentation fault: 11 ``` The underlying issue was that the `DeviceCompilerInstance` (used for device-side CUDA compilation) was never initialized with a `Sema`, which is required before constructing the `IncrementalCUDADeviceParser`. https://github.com/llvm/llvm-project/blob/89687e6f383b742a3c6542dc673a84d9f82d02de/clang/lib/Interpreter/DeviceOffload.cpp#L32 https://github.com/llvm/llvm-project/blob/89687e6f383b742a3c6542dc673a84d9f82d02de/clang/lib/Interpreter/IncrementalParser.cpp#L31 Unlike the host-side `CompilerInstance` which runs `ExecuteAction` inside the Interpreter constructor (thereby setting up Sema), the device-side CI was passed into the parser uninitialized, leading to an assertion or crash when accessing its internals. To fix this, I refactored the `Interpreter::create` method to include an optional `DeviceCI` parameter. If provided, we know we need to take care of this instance too. Only then do we construct the `IncrementalCUDADeviceParser`. (cherry picked from commit 21fb19f)

llvm#138091) Check this error for more context (https://github.com/compiler-research/CppInterOp/actions/runs/14749797085/job/41407625681?pr=491#step:10:531) This fails with ``` * thread #1, name = 'CppInterOpTests', stop reason = signal SIGSEGV: address not mapped to object (fault address: 0x55500356d6d3) * frame #0: 0x00007fffee41cfe3 libclangCppInterOp.so.21.0gitclang::PragmaNamespace::~PragmaNamespace() + 99 frame #1: 0x00007fffee435666 libclangCppInterOp.so.21.0gitclang::Preprocessor::~Preprocessor() + 3830 frame #2: 0x00007fffee20917a libclangCppInterOp.so.21.0gitstd::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release() + 58 frame #3: 0x00007fffee224796 libclangCppInterOp.so.21.0gitclang::CompilerInstance::~CompilerInstance() + 838 frame llvm#4: 0x00007fffee22494d libclangCppInterOp.so.21.0gitclang::CompilerInstance::~CompilerInstance() + 13 frame llvm#5: 0x00007fffed95ec62 libclangCppInterOp.so.21.0gitclang::IncrementalCUDADeviceParser::~IncrementalCUDADeviceParser() + 98 frame llvm#6: 0x00007fffed9551b6 libclangCppInterOp.so.21.0gitclang::Interpreter::~Interpreter() + 102 frame llvm#7: 0x00007fffed95598d libclangCppInterOp.so.21.0gitclang::Interpreter::~Interpreter() + 13 frame llvm#8: 0x00007fffed9181e7 libclangCppInterOp.so.21.0gitcompat::createClangInterpreter(std::vector<char const*, std::allocator<char const*>>&) + 2919 ``` Problem : 1) The destructor currently handles no clearance for the DeviceParser and the DeviceAct. We currently only have this https://github.com/llvm/llvm-project/blob/976493822443c52a71ed3c67aaca9a555b20c55d/clang/lib/Interpreter/Interpreter.cpp#L416-L419 2) The ownership for DeviceCI currently is present in IncrementalCudaDeviceParser. But this should be similar to how the combination for hostCI, hostAction and hostParser are managed by the Interpreter. As on master the DeviceAct and DeviceParser are managed by the Interpreter but not DeviceCI. This is problematic because : IncrementalParser holds a Sema& which points into the DeviceCI. On master, DeviceCI is destroyed before the base class ~IncrementalParser() runs, causing Parser::reset() to access a dangling Sema (and as Sema holds a reference to Preprocessor which owns PragmaNamespace) we see this ``` * frame #0: 0x00007fffee41cfe3 libclangCppInterOp.so.21.0gitclang::PragmaNamespace::~PragmaNamespace() + 99 frame #1: 0x00007fffee435666 libclangCppInterOp.so.21.0gitclang::Preprocessor::~Preprocessor() + 3830 ``` (cherry picked from commit 529b6fc)

Fix unnecessary conversion of C-String to StringRef in the `Cmp` lambda inside `lookupLLVMIntrinsicByName`. This both fixes an ASAN error in the code that happens when the `Name` StringRef passed in is not a Null terminated StringRef, and additionally can potentially speed up the code as well by eliminating the unnecessary computation of string length every time a C String is converted to StringRef in this code (It seems practically this computation is eliminated in optimized builds, but this will avoid it in O0 builds as well). Added a unit test that demonstrates this issue by building LLVM with these options: ``` CMAKE_BUILD_TYPE=Debug LLVM_USE_SANITIZER=Address LLVM_OPTIMIZE_SANITIZED_BUILDS=OFF ``` The error reported is as follows: ``` ==462665==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x5030000391a2 at pc 0x56525cc30bbf bp 0x7fff9e4ccc60 sp 0x7fff9e4cc428 READ of size 19 at 0x5030000391a2 thread T0 #0 0x56525cc30bbe in strlen (upstream-llvm-second/llvm-project/build/unittests/IR/IRTests+0x713bbe) (BuildId: 0651acf1e582a4d2) #1 0x7f8ff22ad334 in std::char_traits<char>::length(char const*) /usr/bin/../lib/gcc/x86_64-linux-gnu/13/../../../../include/c++/13/bits/char_traits.h:399:9 #2 0x7f8ff22a34a0 in llvm::StringRef::StringRef(char const*) /home/rjoshi/upstream-llvm-second/llvm-project/llvm/include/llvm/ADT/StringRef.h:96:33 #3 0x7f8ff28ca184 in _ZZL25lookupLLVMIntrinsicByNameN4llvm8ArrayRefIjEENS_9StringRefES2_ENK3$_0clIjPKcEEDaT_T0_ upstream-llvm-second/llvm-project/llvm/lib/IR/Intrinsics.cpp:673:18 ```

…erver (llvm#148774) Summary: There was a deadlock was introduced by [PR llvm#146441](llvm#146441) which changed `CurrentThreadIsPrivateStateThread()` to `CurrentThreadPosesAsPrivateStateThread()`. This change caused the execution path in [`ExecutionContextRef::SetTargetPtr()`](https://github.com/llvm/llvm-project/blob/10b5558b61baab59c7d3dff37ffdf0861c0cc67a/lldb/source/Target/ExecutionContext.cpp#L513) to now enter a code block that was previously skipped, triggering [`GetSelectedFrame()`](https://github.com/llvm/llvm-project/blob/10b5558b61baab59c7d3dff37ffdf0861c0cc67a/lldb/source/Target/ExecutionContext.cpp#L522) which leads to a deadlock. Thread 1 gets m_modules_mutex in [`ModuleList::AppendImpl`](https://github.com/llvm/llvm-project/blob/96148f92146e5211685246722664e51ec730e7ba/lldb/source/Core/ModuleList.cpp#L218), Thread 3 gets m_language_runtimes_mutex in [`GetLanguageRuntime`](https://github.com/llvm/llvm-project/blob/96148f92146e5211685246722664e51ec730e7ba/lldb/source/Target/Process.cpp#L1501), but then Thread 1 waits for m_language_runtimes_mutex in [`GetLanguageRuntime`](https://github.com/llvm/llvm-project/blob/96148f92146e5211685246722664e51ec730e7ba/lldb/source/Target/Process.cpp#L1501) while Thread 3 waits for m_modules_mutex in [`ScanForGNUstepObjCLibraryCandidate`](https://github.com/llvm/llvm-project/blob/96148f92146e5211685246722664e51ec730e7ba/lldb/source/Plugins/LanguageRuntime/ObjC/GNUstepObjCRuntime/GNUstepObjCRuntime.cpp#L57). This fixes the deadlock by adding a scoped block around the mutex lock before the call to the notifier, and moved the notifier call outside of the mutex-guarded section. The notifier call [`NotifyModuleAdded`](https://github.com/llvm/llvm-project/blob/96148f92146e5211685246722664e51ec730e7ba/lldb/source/Target/Target.cpp#L1810) should be thread-safe, since the module should be added to the `ModuleList` before the mutex is released, and the notifier doesn't modify the module list further, and the call is operates on local state and the `Target` instance. ### Deadlocked Thread backtraces: ``` * thread #3, name = 'dbg.evt-handler', stop reason = signal SIGSTOP * frame #0: 0x00007f2f1e2973dc libc.so.6`futex_wait(private=0, expected=2, futex_word=0x0000563786bd5f40) at futex-internal.h:146:13 /*... a bunch of mutex related bt ... */ liblldb.so.21.0git`std::lock_guard<std::recursive_mutex>::lock_guard(this=0x00007f2f0f1927b0, __m=0x0000563786bd5f40) at std_mutex.h:229:19 frame llvm#8: 0x00007f2f27946eb7 liblldb.so.21.0git`ScanForGNUstepObjCLibraryCandidate(modules=0x0000563786bd5f28, TT=0x0000563786bd5eb8) at GNUstepObjCRuntime.cpp:60:41 frame llvm#9: 0x00007f2f27946c80 liblldb.so.21.0git`lldb_private::GNUstepObjCRuntime::CreateInstance(process=0x0000563785e1d360, language=eLanguageTypeObjC) at GNUstepObjCRuntime.cpp:87:8 frame llvm#10: 0x00007f2f2746fca5 liblldb.so.21.0git`lldb_private::LanguageRuntime::FindPlugin(process=0x0000563785e1d360, language=eLanguageTypeObjC) at LanguageRuntime.cpp:210:36 frame llvm#11: 0x00007f2f2742c9e3 liblldb.so.21.0git`lldb_private::Process::GetLanguageRuntime(this=0x0000563785e1d360, language=eLanguageTypeObjC) at Process.cpp:1516:9 ... frame llvm#21: 0x00007f2f2750b5cc liblldb.so.21.0git`lldb_private::Thread::GetSelectedFrame(this=0x0000563785e064d0, select_most_relevant=DoNoSelectMostRelevantFrame) at Thread.cpp:274:48 frame llvm#22: 0x00007f2f273f9957 liblldb.so.21.0git`lldb_private::ExecutionContextRef::SetTargetPtr(this=0x00007f2f0f193778, target=0x0000563786bd5be0, adopt_selected=true) at ExecutionContext.cpp:525:32 frame llvm#23: 0x00007f2f273f9714 liblldb.so.21.0git`lldb_private::ExecutionContextRef::ExecutionContextRef(this=0x00007f2f0f193778, target=0x0000563786bd5be0, adopt_selected=true) at ExecutionContext.cpp:413:3 frame llvm#24: 0x00007f2f270e80af liblldb.so.21.0git`lldb_private::Debugger::GetSelectedExecutionContext(this=0x0000563785d83bc0) at Debugger.cpp:1225:23 frame llvm#25: 0x00007f2f271bb7fd liblldb.so.21.0git`lldb_private::Statusline::Redraw(this=0x0000563785d83f30, update=true) at Statusline.cpp:136:41 ... * thread #1, name = 'lldb', stop reason = signal SIGSTOP * frame #0: 0x00007f2f1e2973dc libc.so.6`futex_wait(private=0, expected=2, futex_word=0x0000563785e1dd98) at futex-internal.h:146:13 /*... a bunch of mutex related bt ... */ liblldb.so.21.0git`std::lock_guard<std::recursive_mutex>::lock_guard(this=0x00007ffe62be0488, __m=0x0000563785e1dd98) at std_mutex.h:229:19 frame llvm#8: 0x00007f2f2742c8d1 liblldb.so.21.0git`lldb_private::Process::GetLanguageRuntime(this=0x0000563785e1d360, language=eLanguageTypeC_plus_plus) at Process.cpp:1510:41 frame llvm#9: 0x00007f2f2743c46f liblldb.so.21.0git`lldb_private::Process::ModulesDidLoad(this=0x0000563785e1d360, module_list=0x00007ffe62be06a0) at Process.cpp:6082:36 ... frame llvm#13: 0x00007f2f2715cf03 liblldb.so.21.0git`lldb_private::ModuleList::AppendImpl(this=0x0000563786bd5f28, module_sp=ptr = 0x563785cec560, use_notifier=true) at ModuleList.cpp:246:19 frame llvm#14: 0x00007f2f2715cf4c liblldb.so.21.0git`lldb_private::ModuleList::Append(this=0x0000563786bd5f28, module_sp=ptr = 0x563785cec560, notify=true) at ModuleList.cpp:251:3 ... frame llvm#19: 0x00007f2f274349b3 liblldb.so.21.0git`lldb_private::Process::ConnectRemote(this=0x0000563785e1d360, remote_url=(Data = "connect://localhost:1234", Length = 24)) at Process.cpp:3250:9 frame llvm#20: 0x00007f2f27411e0e liblldb.so.21.0git`lldb_private::Platform::DoConnectProcess(this=0x0000563785c59990, connect_url=(Data = "connect://localhost:1234", Length = 24), plugin_name=(Data = "gdb-remote", Length = 10), debugger=0x0000563785d83bc0, stream=0x00007ffe62be3128, target=0x0000563786bd5be0, error=0x00007ffe62be1ca0) at Platform.cpp:1926:23 ``` ## Test Plan: Built a hello world a.out Run server in one terminal: ``` ~/llvm/build/Debug/bin/lldb-server g :1234 a.out ``` Run client in another terminal ``` ~/llvm/build/Debug/bin/lldb -o "gdb-remote 1234" -o "b hello.cc:3" ``` Before: Client hangs indefinitely ``` ~/llvm/build/Debug/bin/lldb -o "gdb-remote 1234" -o "b main" (lldb) gdb-remote 1234 ^C^C ``` After: ``` ~/llvm/build/Debug/bin/lldb -o "gdb-remote 1234" -o "b hello.cc:3" (lldb) gdb-remote 1234 Process 837068 stopped * thread #1, name = 'a.out', stop reason = signal SIGSTOP frame #0: 0x00007ffff7fe4a60 ld-linux-x86-64.so.2`_start: -> 0x7ffff7fe4a60 <+0>: movq %rsp, %rdi 0x7ffff7fe4a63 <+3>: callq 0x7ffff7fe5780 ; _dl_start at rtld.c:522:1 ld-linux-x86-64.so.2`_dl_start_user: 0x7ffff7fe4a68 <+0>: movq %rax, %r12 0x7ffff7fe4a6b <+3>: movl 0x18067(%rip), %eax ; _dl_skip_args (lldb) b hello.cc:3 Breakpoint 1: where = a.out`main + 15 at hello.cc:4:13, address = 0x00005555555551bf (lldb) c Process 837068 resuming Process 837068 stopped * thread #1, name = 'a.out', stop reason = breakpoint 1.1 frame #0: 0x00005555555551bf a.out`main at hello.cc:4:13 1 #include <iostream> 2 3 int main() { -> 4 std::cout << "Hello World" << std::endl; 5 return 0; 6 } ```

AdamGlass force-pushed the inliner-section-safety branch from bdc71cc to 5377615 Compare July 3, 2025 04:32

MSVC inliner section behavior compat

7bf07fb

AdamGlass force-pushed the inliner-section-safety branch from 5377615 to 7bf07fb Compare July 3, 2025 16:12

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