[llvm-dev] Linux/ARM: Segfault issue when we build clang sources including __thread variable using -O2 flag
Geunsik Lim via llvm-dev
llvm-dev at lists.llvm.org
Tue May 3 01:55:43 PDT 2016
Now, There are four thread local storage (TLS) models in Clang/LLVM as
following:
1) global-dynamic TLS model
2) local-dynamic TLS model
3) local-exec TLS model
4) initial-exec TLS model
and emulated-TLS (for Android S/W platform)??
Even though, We can build run normally with the static relocation method by
selecting the initial-exec TLS model instead of global-dynamic TLS
model (by default) , We need to run the clang application code with
global-dynamic (or local-dynamic) TLS model in order that we consider an
application code is working with dlopen(3) library call.
If someone have already found the appropriate solution for some clang/LLVM
applications including 1) __thread variables and 2) -O2/-O3 of the clang
language, Could you share us?
On Tue, May 3, 2016 at 5:14 PM, Geunsik Lim <leemgs at gmail.com> wrote:
> A few days ago, I tried to change the optimization flag from -O0 to -O2 to
> speed up the execution of the application on Ubuntu/ARM 14.04 32 bit.
> When I compiled the source code with -O2 flag instead of -O0 flag, I
> could not run the application normally by getting always the segmentation
> fault.
>
> Here is debugging information with GDB command in case of that. As you can
> see, we could not execute simple hello!! console application
> because of the bug of clang/LLVM when we try to use "static __thread"
> variable with -O2 flag.
>
> *root:/dotnet/runtime.release.20160322.2/example> gdb ../corerun ./core.20160322*
> GNU gdb (GDB) 7.9.1
> Copyright (C) 2015 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law. Type "show copying"
> and "show warranty" for details.
> This GDB was configured as "armv7l-tizen-linux-gnueabi".
> Type "show configuration" for configuration details.
> For bug reporting instructions, please see:
> <http://www.gnu.org/software/gdb/bugs/>.
> Find the GDB manual and other documentation resources online at:
> <http://www.gnu.org/software/gdb/documentation/>.
> For help, type "help".
> Type "apropos word" to search for commands related to "word"...
> Reading symbols from ../corerun...(no debugging symbols found)...done.
> [New LWP 742]
> [New LWP 745]
> [New LWP 744]
> [New LWP 743]
> [New LWP 746]
>
> warning: File "/lib/arm-linux-gnueabihf/libthread_db-1.0.so" auto-loading has been declined
> by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".
> To enable execution of this file add
> add-auto-load-safe-path /lib/arm-linux-gnueabihf/libthread_db-1.0.so
> line to your configuration file "//.gdbinit".
> To completely disable this security protection add
> set auto-load safe-path /
> line to your configuration file "//.gdbinit".
> For more information about this security protection see the
> "Auto-loading safe path" section in the GDB manual. E.g., run from the shell:
> info "(gdb)Auto-loading safe path"
>
> warning: Unable to find libthread_db matching inferior's thread library, thread debugging will not be available.
>
> warning: File "/lib/arm-linux-gnueabihf/libthread_db-1.0.so" auto-loading has been declined
> by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".
>
> warning: Unable to find libthread_db matching inferior's thread library, thread debugging will not be available.
> ---Type <return> to continue, or q <return> to quit---
> Core was generated by `../corerun -c .. ./hello.exe'.
> Program terminated with signal SIGSEGV, Segmentation fault.
> #0 0x76f7a410 in __tls_get_addr () from /lib/ld-linux-armhf.so.3
> (gdb) thread info
> No symbol "info" in current context.
> (gdb) bt
> #0 0x76f7a410 in __tls_get_addr () from /lib/ld-linux-armhf.so.3
> #1 0x7699787c in ClassLoader::LoadTypeHandleForTypeKey_Body(TypeKey*, TypeHandle, ClassLoadLevel) () from /dotnet/runtime.release.20160222.2/libcoreclr.so
> #2 0x76994c4a in ClassLoader::LoadTypeHandleForTypeKey(TypeKey*, TypeHandle, ClassLoadLevel, InstantiationContext const*) ()
> from /dotnet/runtime.release.20160222.2/libcoreclr.so
> #3 0x76995a38 in ClassLoader::LoadTypeDefThrowing(Module*, unsigned int, ClassLoader::NotFoundAction, ClassLoader::PermitUninstantiatedFlag, unsigned int, ClassLoadLevel, Instantiation*) ()
> from /dotnet/runtime.release.20160222.2/libcoreclr.so
> #4 0x769939f2 in ClassLoader::LoadTypeHandleThrowing(NameHandle*, ClassLoadLevel, Module*) () from /dotnet/runtime.release.20160222.2/libcoreclr.so
> #5 0x769937c2 in ClassLoader::LoadTypeByNameThrowing(Assembly*, char const*, char const*, ClassLoader::NotFoundAction, ClassLoader::LoadTypesFlag, ClassLoadLevel) () from /dotnet/runtime.release.20160222.2/libcoreclr.so
> #6 0x76980918 in MscorlibBinder::LookupClass(BinderClassID) ()
> from /dotnet/runtime.release.20160222.2/libcoreclr.so
> #7 0x769675ca in SystemDomain::LoadBaseSystemClasses() ()
> from /dotnet/runtime.release.20160222.2/libcoreclr.so
> #8 0x769673ac in SystemDomain::Init() ()
> from /dotnet/runtime.release.20160222.2/libcoreclr.so
> #9 0x768dbc16 in EEStartupHelper(tagCOINITEE) ()
> from /dotnet/runtime.release.20160222.2/libcoreclr.so
> ---Type <return> to continue, or q <return> to quit---
> #10 0x768db070 in EEStartup(tagCOINITEE) ()
> from /dotnet/runtime.release.20160222.2/libcoreclr.so
> #11 0x768daf56 in EnsureEEStarted(tagCOINITEE) ()
> from /dotnet/runtime.release.20160222.2/libcoreclr.so
> #12 0x76857998 in CorHost2::Start() ()
> from /dotnet/runtime.release.20160222.2/libcoreclr.so
> #13 0x76842eac in coreclr_initialize ()
> from /dotnet/runtime.release.20160222.2/libcoreclr.so
> #14 0x0000a52e in ExecuteManagedAssembly(char const*, char const*, char const*, int, char const**) ()
> #15 0x00009852 in corerun(int, char const**) ()
> #16 0x76d38632 in __libc_start_main () from /lib/arm-linux-gnueabihf/libc.so.6
> #17 0x00009590 in _start ()
> Backtrace stopped: previous frame identical to this frame (corrupt stack?)
> (gdb)
> (gdb)
> (gdb)
> (gdb)
>
>
>
>
> At that time, I defined the "global-dynamic" TLS model by default with
> Clang/LLVM compiler as following:
> SET (CMAKE_C_FLAGS_INIT "-Wall -std=c11
> -ftls-model=global-dynamic")
>
> We can build and run hello!!! console application with clang/LLVM with -O1
> optimization level for Ubuntu/ARM 14.04 32bit as following.
> src/pal/tools/clang-compiler-override.txt | 13 +++++++++++--
>
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/src/pal/tools/clang-compiler-override.txt b/src/pal/tools/clang-compiler-override.txt
> index 8bba4a9..ba86d15 100644
> --- a/src/pal/tools/clang-compiler-override.txt
> +++ b/src/pal/tools/clang-compiler-override.txt
> @@ -1,13 +1,22 @@
> SET (CMAKE_C_FLAGS_INIT "-Wall -std=c11")
> SET (CMAKE_C_FLAGS_DEBUG_INIT "-g -O0")
> SET (CLR_C_FLAGS_CHECKED_INIT "-g -O2")
> -SET (CMAKE_C_FLAGS_RELEASE_INIT "-g -O3")
> +if(CMAKE_SYSTEM_NAME STREQUAL Linux AND CMAKE_SYSTEM_PROCESSOR STREQUAL armv7l)
> + SET (CMAKE_C_FLAGS_RELEASE_INIT "-g0 -O1")
> +else()
> + SET (CMAKE_C_FLAGS_RELEASE_INIT "-g0 -O3")
> + message(FATAL_ERROR "RELEASE... c flag no-arm")
> +endif()
> SET (CMAKE_C_FLAGS_RELWITHDEBINFO_INIT "-g -O2")
>
> SET (CMAKE_CXX_FLAGS_INIT "-Wall -Wno-null-conversion -std=c++11")
> SET (CMAKE_CXX_FLAGS_DEBUG_INIT "-g -O0")
> SET (CLR_CXX_FLAGS_CHECKED_INIT "-g -O2")
> -SET (CMAKE_CXX_FLAGS_RELEASE_INIT "-g -O3")
> +if(CMAKE_SYSTEM_NAME STREQUAL Linux AND CMAKE_SYSTEM_PROCESSOR STREQUAL armv7l)
> + SET (CMAKE_CXX_FLAGS_RELEASE_INIT "-g0 -O1")
> +else()
> + SET (CMAKE_CXX_FLAGS_RELEASE_INIT "-g0 -O3")
> +endif()
> SET (CMAKE_CXX_FLAGS_RELWITHDEBINFO_INIT "-g -O2")
>
>
> In the summary, We can build and run clang/LLVM source code including
> __thread variable with -O1 /-O2 flags.
>
> However, We cannot run (build is okay.) normally hello!!! console
> application with clang/LLVM using -O2 and -O3 optimization level.
>
> Anyone who has similar experience that gets the __thread variable issue
> with -O2/-O3 flags like me?
>
>
>
>
>
>
>
> --
> http://leemgs.fedorapeople.org
> Don't try to avoid pain if you fail.
> If you decided to face the challenges in life,
> you can gain a lot by giving your best.
> Cheolsang Jeong's Book & life
> --
>
--
http://leemgs.fedorapeople.org
Don't try to avoid pain if you fail.
If you decided to face the challenges in life,
you can gain a lot by giving your best.
Cheolsang Jeong's Book & life
--
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