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When the main loop is e.g. VF=vscale x 1 and the epilogue VF cannot be any smaller, the vectorizer should try to estimate how many lanes are executed at runtime and allow a suitable fixed-width VF to be chosen. It can use VScaleForTuning to figure out what a suitable fixed-width VF could be. For the case where the main loop VF is VF=vscale x 1, and VScaleForTuning=8, it could still choose an epilogue VF upto VF=4. This was a bit tricky to test, so this patch also introduces a wrapper function to get 'VScaleForTuning' by also considering vscale_range. If min and max are equal, then that will be the vscale we compile for. It makes little sense to tune for a different width if the code will not be portable for other widths. Reviewed By: david-arm Differential Revision: https://reviews.llvm.org/D118709 (cherry picked from commit eaee477)
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Feb 10, 2022
We experienced some deadlocks when we used multiple threads for logging using `scan-builds` intercept-build tool when we used multiple threads by e.g. logging `make -j16` ``` (gdb) bt #0 0x00007f2bb3aff110 in __lll_lock_wait () from /lib/x86_64-linux-gnu/libpthread.so.0 #1 0x00007f2bb3af70a3 in pthread_mutex_lock () from /lib/x86_64-linux-gnu/libpthread.so.0 #2 0x00007f2bb3d152e4 in ?? () #3 0x00007ffcc5f0cc80 in ?? () #4 0x00007f2bb3d2bf5b in ?? () from /lib64/ld-linux-x86-64.so.2 #5 0x00007f2bb3b5da27 in ?? () from /lib/x86_64-linux-gnu/libc.so.6 #6 0x00007f2bb3b5dbe0 in exit () from /lib/x86_64-linux-gnu/libc.so.6 #7 0x00007f2bb3d144ee in ?? () #8 0x746e692f706d742f in ?? () #9 0x692d747065637265 in ?? () #10 0x2f653631326b3034 in ?? () #11 0x646d632e35353532 in ?? () #12 0x0000000000000000 in ?? () ``` I think the gcc's exit call caused the injected `libear.so` to be unloaded by the `ld`, which in turn called the `void on_unload() __attribute__((destructor))`. That tried to acquire an already locked mutex which was left locked in the `bear_report_call()` call, that probably encountered some error and returned early when it forgot to unlock the mutex. All of these are speculation since from the backtrace I could not verify if frames 2 and 3 are in fact corresponding to the `libear.so` module. But I think it's a fairly safe bet. So, hereby I'm releasing the held mutex on *all paths*, even if some failure happens. PS: I would use lock_guards, but it's C. Reviewed-by: NoQ Differential Revision: https://reviews.llvm.org/D118439 (cherry picked from commit d919d02)
tstellar
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Feb 14, 2022
We experienced some deadlocks when we used multiple threads for logging using `scan-builds` intercept-build tool when we used multiple threads by e.g. logging `make -j16` ``` (gdb) bt #0 0x00007f2bb3aff110 in __lll_lock_wait () from /lib/x86_64-linux-gnu/libpthread.so.0 #1 0x00007f2bb3af70a3 in pthread_mutex_lock () from /lib/x86_64-linux-gnu/libpthread.so.0 #2 0x00007f2bb3d152e4 in ?? () #3 0x00007ffcc5f0cc80 in ?? () #4 0x00007f2bb3d2bf5b in ?? () from /lib64/ld-linux-x86-64.so.2 #5 0x00007f2bb3b5da27 in ?? () from /lib/x86_64-linux-gnu/libc.so.6 #6 0x00007f2bb3b5dbe0 in exit () from /lib/x86_64-linux-gnu/libc.so.6 #7 0x00007f2bb3d144ee in ?? () #8 0x746e692f706d742f in ?? () #9 0x692d747065637265 in ?? () #10 0x2f653631326b3034 in ?? () #11 0x646d632e35353532 in ?? () #12 0x0000000000000000 in ?? () ``` I think the gcc's exit call caused the injected `libear.so` to be unloaded by the `ld`, which in turn called the `void on_unload() __attribute__((destructor))`. That tried to acquire an already locked mutex which was left locked in the `bear_report_call()` call, that probably encountered some error and returned early when it forgot to unlock the mutex. All of these are speculation since from the backtrace I could not verify if frames 2 and 3 are in fact corresponding to the `libear.so` module. But I think it's a fairly safe bet. So, hereby I'm releasing the held mutex on *all paths*, even if some failure happens. PS: I would use lock_guards, but it's C. Reviewed-by: NoQ Differential Revision: https://reviews.llvm.org/D118439 (cherry picked from commit d919d02)
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Jan 24, 2024
…8055) This fixes a crash where `path::parent_path` causes an invalid access on a string upon receiving a path that consists of a single colon. On Windows machine, with runtime checks enabled build, upon `clang -I: test.cc` produces: ``` Assertion failed: Index < Length && "Invalid index!", file llvm\include\llvm/ADT/StringRef.h, line 232 ... #6 0x00007ff7816201eb `anonymous namespace'::parent_path_end llvm\lib\Support\Path.cpp:144:0 #7 0x00007ff781620135 llvm::sys::path::parent_path(class llvm::StringRef, enum llvm::sys::path::Style) llvm\lib\Support\Path.cpp:470:0 ``` Ideally, we can look for the last colon starting from the last character, but we can instead start from second to last, and handle empty paths by abusing `0 - 1 == npos`.
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Apr 28, 2025
`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) #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) #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) #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) #7 0x000000010206f8a8 main (/opt/local/libexec/llvm-20/bin/clang-repl+0x1000038a8) #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)
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Apr 29, 2025
`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) #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) #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) #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) #7 0x000000010206f8a8 main (/opt/local/libexec/llvm-20/bin/clang-repl+0x1000038a8) #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)
llvmbot
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May 6, 2025
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 #4: 0x00007fffee22494d libclangCppInterOp.so.21.0gitclang::CompilerInstance::~CompilerInstance() + 13 frame #5: 0x00007fffed95ec62 libclangCppInterOp.so.21.0gitclang::IncrementalCUDADeviceParser::~IncrementalCUDADeviceParser() + 98 frame #6: 0x00007fffed9551b6 libclangCppInterOp.so.21.0gitclang::Interpreter::~Interpreter() + 102 frame #7: 0x00007fffed95598d libclangCppInterOp.so.21.0gitclang::Interpreter::~Interpreter() + 13 frame #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)
llvmbot
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May 9, 2025
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 #4: 0x00007fffee22494d libclangCppInterOp.so.21.0gitclang::CompilerInstance::~CompilerInstance() + 13 frame #5: 0x00007fffed95ec62 libclangCppInterOp.so.21.0gitclang::IncrementalCUDADeviceParser::~IncrementalCUDADeviceParser() + 98 frame #6: 0x00007fffed9551b6 libclangCppInterOp.so.21.0gitclang::Interpreter::~Interpreter() + 102 frame #7: 0x00007fffed95598d libclangCppInterOp.so.21.0gitclang::Interpreter::~Interpreter() + 13 frame #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)
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resolves llvm#53585