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From 60854c328d8729b2ef10b9bb4dcbcc282f43c5e7 Mon Sep 17 00:00:00 2001
From: Raphael Isemann <teemperor@gmail.com>
Date: Thu, 1 Apr 2021 18:41:44 +0200
Subject: [PATCH] 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 [https://github.com/llvm/llvm-project/commit/60854c328d8729b2ef10b9bb4dcbcc282f43c5e7]
Signed-off-by: Naveen Saini <naveen.kumar.saini@intel.com>
---
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 41eafd13d97c..00d92e7beadd 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -871,7 +871,15 @@ 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());
}
--
2.29.2
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