From 747e48959e18ac8b586078a82472a0799d12925c Mon Sep 17 00:00:00 2001 From: Raphael Isemann Date: Thu, 1 Apr 2021 18:41:44 +0200 Subject: [PATCH 5/6] Avoid calling ParseCommandLineOptions in BackendUtil if possible Calling `ParseCommandLineOptions` should only be called from `main` as the CommandLine setup code isn't thread-safe. As BackendUtil is part of the generic Clang FrontendAction logic, a process which has several threads executing Clang FrontendActions will randomly crash in the unsafe setup code. This patch avoids calling the function unless either the debug-pass option or limit-float-precision option is set. Without these two options set the `ParseCommandLineOptions` call doesn't do anything beside parsing the command line `clang` which doesn't set any options. See also D99652 where LLDB received a workaround for this crash. Reviewed By: JDevlieghere Differential Revision: https://reviews.llvm.org/D99740 Upstream-Status: Backport [Taken from opencl-clang patches; https://github.com/intel/opencl-clang/blob/ocl-open-110/patches/clang/0003-Avoid-calling-ParseCommandLineOptions-in-BackendUtil.patch] Signed-off-by: Naveen Saini --- clang/lib/CodeGen/BackendUtil.cpp | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp index dce0940670a2..ab478090ed1c 100644 --- a/clang/lib/CodeGen/BackendUtil.cpp +++ b/clang/lib/CodeGen/BackendUtil.cpp @@ -797,7 +797,15 @@ static void setCommandLineOpts(const CodeGenOptions &CodeGenOpts) { BackendArgs.push_back("-limit-float-precision"); BackendArgs.push_back(CodeGenOpts.LimitFloatPrecision.c_str()); } + // Check for the default "clang" invocation that won't set any cl::opt values. + // Skip trying to parse the command line invocation to avoid the issues + // described below. + if (BackendArgs.size() == 1) + return; BackendArgs.push_back(nullptr); + // FIXME: The command line parser below is not thread-safe and shares a global + // state, so this call might crash or overwrite the options of another Clang + // instance in the same process. llvm::cl::ParseCommandLineOptions(BackendArgs.size() - 1, BackendArgs.data()); } -- 2.17.1