llvm dev - Jul 2016 - help please: how to sort the contents of a "SymbolTableListTraits<GlobalVariable>"?

Dear all,

In the process of trying to add optimization for better layout of global
variables, I have run
up against a roadblock: I don`t seem to be able to sort the contents of a 
"SymbolTableListTraits<GlobalVariable>" -- or even swap two
elements in that list -- without
causing LLVM to crash.

I have tried writing a comparator class and then using "llvm::iplist<
NodeTy, Traits
 >::sort(Compare comp)" 
[<http://llvm.org/docs/doxygen/html/classllvm_1_1iplist.html#a81afd2c47bb276cd50c78c74b3f92ec3>],
since "llvm::Module::GlobalListType" 
[<http://llvm.org/docs/doxygen/html/classllvm_1_1Module.html#accd281de11bad056a32f319d7facafe3>]
is an alias for "SymbolTableList<GlobalVariable>" and according
to the Web-based documentation
every instantiation of SymbolTableList 
[<http://llvm.org/docs/doxygen/html/classllvm_1_1SymbolTableList.html>]
is-an instantiation of
"iplist"
[<http://llvm.org/docs/doxygen/html/classllvm_1_1iplist.html>].  This call
to "sort"
crashed badly.  I`ll paste in the code for this attempt below [simplified for
clarity], but not
the code for the others since they are longer and more "desperate".

All my attempts to write anything that might be the innermost operation in a
"sort" I would
write myself either would not compile or would compile and crash at run-time. 
The ones that
wouldn`t compile wouldn`t compile because GlobalVariable has an
explicitly-deleted copy
constructor and no move constructor [so "std::move(...)" was not
usable to solve the problem].

BTW: I am [and was] doing this in the context of "OptimizeGlobalVars"
which is in
"llvm/lib/Transforms/IPO/GlobalOpt.cpp".

If anybody reading this can provide some assistance, I`d be much obliged.

Regards,

Abe








   struct GV_alignment_comparator {
     bool operator()(const GlobalVariable& L, const GlobalVariable& R) {
       return L.getAlignment() < R.getAlignment();
     }
   };

   // 'M' is a "Module &"

/* this crashes BADLY...  :-(
   M.getGlobalList().sort( GV_alignment_comparator() );
   Changed = true;
*/

> On 2016-Jul-27, at 11:20, Abe Skolnik via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> Dear all,
> 
> In the process of trying to add optimization for better layout of global
variables, I have run up against a roadblock: I don`t seem to be able to sort
the contents of a "SymbolTableListTraits<GlobalVariable>" -- or
even swap two elements in that list -- without causing LLVM to crash.
> 
> I have tried writing a comparator class and then using
"llvm::iplist< NodeTy, Traits >::sort(Compare comp)"
[<http://llvm.org/docs/doxygen/html/classllvm_1_1iplist.html#a81afd2c47bb276cd50c78c74b3f92ec3>],
since "llvm::Module::GlobalListType"
[<http://llvm.org/docs/doxygen/html/classllvm_1_1Module.html#accd281de11bad056a32f319d7facafe3>]
is an alias for "SymbolTableList<GlobalVariable>" and according
to the Web-based documentation every instantiation of SymbolTableList
[<http://llvm.org/docs/doxygen/html/classllvm_1_1SymbolTableList.html>]
is-an instantiation of "iplist"
[<http://llvm.org/docs/doxygen/html/classllvm_1_1iplist.html>].  This call
to "sort" crashed badly.
Crashed how?  Have you turned on ASan?  You might file a PR (feel free to CC
me).  I recommend attaching a minimal reproduction... I assume you can reproduce
this in a unit test?  That's easiest.

I just had a look at the sort code, and I don't see anything obviously
wrong.
> I`ll paste in the code for this attempt below [simplified for clarity], but
not the code for the others since they are longer and more
"desperate".
> 
> All my attempts to write anything that might be the innermost operation in
a "sort" I would write myself either would not compile or would
compile and crash at run-time.  The ones that wouldn`t compile wouldn`t compile
because GlobalVariable has an explicitly-deleted copy constructor and no move
constructor [so "std::move(...)" was not usable to solve the problem].
> 
> BTW: I am [and was] doing this in the context of
"OptimizeGlobalVars" which is in
"llvm/lib/Transforms/IPO/GlobalOpt.cpp".
> 
> If anybody reading this can provide some assistance, I`d be much obliged.
> 
> Regards,
> 
> Abe
> 
> 
> 
> 
> 
> 
> 
> 
>  struct GV_alignment_comparator {
>    bool operator()(const GlobalVariable& L, const GlobalVariable&
R) {
>      return L.getAlignment() < R.getAlignment();
>    }
>  };
> 
>  // 'M' is a "Module &"
> 
> /* this crashes BADLY...  :-(
>  M.getGlobalList().sort( GV_alignment_comparator() );
>  Changed = true;
> */
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

Dear sir,

Thanks for your reply.  I apologize for taking a few days to reply.

> Crashed how?
Please see the below.

> Have you turned on ASan?
Not yet, but thanks for the suggestion.  I guess I will try to rebuild my
modified Clang+LLVM
with addr. san. and see what happens.

>  I recommend attaching a minimal reproduction...
Well, since I`m hacking on LLVM itself, this is not 100% trivial.  I will
explain.

The first hurdle I had to overcome was the fact that the
"GlobalVariable" class had an
explicitly-deleted copy ctor and no move ctor.  I dealt with this by writing a
copy ctor; I`ll
paste that in below.

A perhaps-important point is that I don`t know _why_ the
"GlobalVariable" class had an
explicitly-deleted copy ctor and no move ctor.  As an experiment, I moved
forward with the
hypothesis that this was simply because neither was needed at the time and the
default [i.e.
compiler-inserted] copy ctor would have been wrong.  I hope the one _I_ wrote is
_right_.  ;-)

> I assume you can reproduce this in a unit test?
Well, it doesn`t take a long program-under-compilation to make this fail.  As
before, I will
paste something in after my sign-off.


Regards,

Abe





----- added near the end of "OptimizeGlobalVars" in
"llvm/lib/Transforms/IPO/GlobalOpt.cpp",
amongst many other things I added to that routine -----

struct GV_alignment_comparator {
    bool operator()(const GlobalVariable& L, const GlobalVariable& R) {
      return L.getAlignment() < R.getAlignment();
    }
};

if (unsorted) {
    M.getGlobalList().sort( GV_alignment_comparator() );
    Changed = true;
}



----- added to "llvm/lib/IR/Globals.cpp" [and commented out the
relevant deletion in
"llvm/include/llvm/IR/GlobalVariable.h"] -----

GlobalVariable::GlobalVariable(const GlobalVariable& GV) : GlobalVariable(
GV.getValueType(),
GV.isConstant(), GV.getLinkage() ) { // copy ctor
    copyAttributesFrom(&GV);
}





main_with_3_globals.c
---------------------

int  foo;
char bar;
long baz;

int main(){return foo;}










----- error dump from compiler driver -----
> ../build_003/bin/clang main_with_3_globals.c -O3
Abe was here: max. profitable alignment: 16

Abe was here: found a global value that DOES have a name [“foo”],
    with alignment 4,
    no named section [double-check: should be empty string: “”],
    which is a pointer to a NON-array
    and with pointee type getTypeStoreSize -> 4

Abe was here: found a global value that DOES have a name [“bar”],
    with alignment 1,
    no named section [double-check: should be empty string: “”],
    which is a pointer to a NON-array
    and with pointee type getTypeStoreSize -> 1

Abe was here: found a global value that DOES have a name [“baz”],
    with alignment 8,
    no named section [double-check: should be empty string: “”],
    which is a pointer to a NON-array
    and with pointee type getTypeStoreSize -> 8

===== Abe was here: the globals above are NOT in ascending-alignment order.
====0  clang-3.9       0x0000000002853ebc
llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 60
1  clang-3.9       0x00000000028543a9
2  clang-3.9       0x0000000002852a83 llvm::sys::RunSignalHandlers() + 131
3  clang-3.9       0x00000000028546f4
4  libpthread.so.0 0x00007fc595318330
5  clang-3.9       0x00000000027fbe12
llvm::StringMapImpl::LookupBucketFor(llvm::StringRef) + 466
6  clang-3.9       0x0000000002320fa4
7  clang-3.9       0x0000000002320a10
llvm::ValueSymbolTable::reinsertValue(llvm::Value*) + 112
8  clang-3.9       0x00000000022f0551 
llvm::SymbolTableListTraits<llvm::GlobalVariable>::transferNodesFromList(llvm::SymbolTableListTraits<llvm::GlobalVariable>&,
llvm::ilist_iterator<llvm::GlobalVariable>,
llvm::ilist_iterator<llvm::GlobalVariable>) + 273
9  clang-3.9       0x00000000023b1fd9
10 clang-3.9       0x00000000023b1c45
11 clang-3.9       0x00000000023a8e40
12 clang-3.9       0x000000000239e77c
13 clang-3.9       0x000000000239d88e
14 clang-3.9       0x00000000023a9f8c
15 clang-3.9       0x00000000022ac02a
16 clang-3.9       0x00000000022abb56
llvm::legacy::PassManagerImpl::run(llvm::Module&) + 342
17 clang-3.9       0x00000000022ac541
llvm::legacy::PassManager::run(llvm::Module&) + 33
18 clang-3.9       0x0000000002adf7c5
19 clang-3.9       0x0000000002adeda6
clang::EmitBackendOutput(clang::DiagnosticsEngine&,
clang::CodeGenOptions const&, clang::TargetOptions const&,
clang::LangOptions const&,
llvm::DataLayout const&, llvm::Module*, clang::BackendAction, 
std::unique_ptr<llvm::raw_pwrite_stream,
std::default_delete<llvm::raw_pwrite_stream> >) + 150
20 clang-3.9       0x00000000035d622f
21 clang-3.9       0x0000000004259504 clang::ParseAST(clang::Sema&, bool,
bool) + 820
22 clang-3.9       0x00000000030f011a clang::ASTFrontendAction::ExecuteAction()
+ 314
23 clang-3.9       0x00000000035d4bf5 clang::CodeGenAction::ExecuteAction() +
2357
24 clang-3.9       0x00000000030efc00 clang::FrontendAction::Execute() + 112
25 clang-3.9       0x0000000003094c81 
clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) + 1025
26 clang-3.9       0x0000000003241ba1 
clang::ExecuteCompilerInvocation(clang::CompilerInstance*) + 1473
27 clang-3.9       0x0000000000c33bc8 cc1_main(llvm::ArrayRef<char
const*>, char const*, void*)
+ 920
28 clang-3.9       0x0000000000c27c2a
29 clang-3.9       0x0000000000c26ae2 main + 2642
30 libc.so.6       0x00007fc593e80f45 __libc_start_main + 245
31 clang-3.9       0x0000000000c25f44
Stack dump:
0.      Program arguments: 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/build_003/bin/clang-3.9
-cc1 -triple x86_64-unknown-linux-gnu -emit-obj -disable-free -main-file-name 
main_with_3_globals.c -mrelocation-model static -mthread-model posix
-fmath-errno -masm-verbose
-mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 
-momit-leaf-frame-pointer -dwarf-column-info -debugger-tuning=gdb -resource-dir 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/build_003/bin/../lib/clang/3.9.0
-internal-isystem /usr/local/include -internal-isystem 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/build_003/bin/../lib/clang/3.9.0/include
-internal-externc-isystem /usr/include/x86_64-linux-gnu
-internal-externc-isystem /include
-internal-externc-isystem /usr/include -O3 -fdebug-compilation-dir 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/tmp
-ferror-limit 19 -fmessage-length 144 -fobjc-runtime=gcc
-fdiagnostics-show-option
-fcolor-diagnostics -vectorize-loops -vectorize-slp -o
/tmp/main_with_3_globals-cef92e.o -x c
main_with_3_globals.c
1.      <eof> parser at end of file
2.      Per-module optimization passes
3.      Running pass 'Global Variable Optimizer' on module
'main_with_3_globals.c'.
clang-3.9: error: unable to execute command: Segmentation fault
clang-3.9: error: clang frontend command failed due to signal (use -v to see
invocation)
clang version 3.9.0
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/tmp/../build_003/bin
clang-3.9: note: diagnostic msg: PLEASE submit a bug report to
http://llvm.org/bugs/ and
include the crash backtrace, preprocessed source, and associated run script.
clang-3.9: note: diagnostic msg:
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang-3.9: note: diagnostic msg: /tmp/main_with_3_globals-841619.c
clang-3.9: note: diagnostic msg: /tmp/main_with_3_globals-841619.sh
clang-3.9: note: diagnostic msg:

********************




GDB backtrace from the "-cc1" part of another run of the
same-as-the-preceding compilation attempt
--------------------------------------------------------------------------------------------------

Program received signal SIGSEGV, Segmentation fault.
0x00000000027fbe12 in llvm::StringMapImpl::LookupBucketFor (this=0x82f00e8,
Name=...)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/Support/StringMap.cpp:102
102         } else if (LLVM_LIKELY(HashTable[BucketNo] == FullHashValue)) {
(gdb) bt
#0  0x00000000027fbe12 in llvm::StringMapImpl::LookupBucketFor (this=0x82f00e8,
Name=...)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/Support/StringMap.cpp:102
#1  0x0000000002320fa4 in llvm::StringMap<llvm::Value*,
llvm::MallocAllocator>::insert
(this=0x82f00e8, KeyValue=0x8312cb0)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/include/llvm/ADT/StringMap.h:345
#2  0x0000000002320a10 in llvm::ValueSymbolTable::reinsertValue (this=0x82f00e8,
V=0x830cfd8)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/IR/ValueSymbolTable.cpp:59
#3  0x00000000022f0551 in 
llvm::SymbolTableListTraits<llvm::GlobalVariable>::transferNodesFromList
(this=0x7fffffffabd8,
L2=..., first=...,
      last=...)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/IR/SymbolTableListTraitsImpl.h:102
#4  0x00000000023b1fd9 in llvm::iplist<llvm::GlobalVariable, 
llvm::SymbolTableListTraits<llvm::GlobalVariable> >::transfer (
      this=0x7fffffffabd8, position=..., L2=..., first=..., last=...)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/include/llvm/ADT/ilist.h:532
#5  0x00000000023b1c45 in llvm::iplist<llvm::GlobalVariable, 
llvm::SymbolTableListTraits<llvm::GlobalVariable> >::splice
(this=0x7fffffffabd8,
      where=..., L2=..., first=..., last=...)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/include/llvm/ADT/ilist.h:587
#6  0x00000000023a8e40 in llvm::iplist<llvm::GlobalVariable, 
llvm::SymbolTableListTraits<llvm::GlobalVariable>
>::sort<OptimizeGlobalVars(llvm::Module&,
llvm::TargetLibraryInfo*, llvm::function_ref<llvm::DominatorTree&
(llvm::Function&)>,
llvm::SmallSet<llvm::Comdat const*, 8u, std::less<llvm::Comdat const*> 
 >&)::GV_alignment_comparator>(OptimizeGlobalVars(llvm::Module&,
llvm::TargetLibraryInfo*,
llvm::function_ref<llvm::DominatorTree& (llvm::Function&)>,
llvm::SmallSet<llvm::Comdat const*,
8u, std::less<llvm::Comdat const*> >&)::GV_alignment_comparator) (
      this=0x82b1f98, comp=...)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/include/llvm/ADT/ilist.h:632
#7  0x000000000239e77c in OptimizeGlobalVars(llvm::Module&,
llvm::TargetLibraryInfo*,
llvm::function_ref<llvm::DominatorTree& (llvm::Function&)>,
llvm::SmallSet<llvm::Comdat const*,
8u, std::less<llvm::Comdat const*> >&) (M=..., TLI=0x8293860,
LookupDomTree=...,
      NotDiscardableComdats=...)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/Transforms/IPO/GlobalOpt.cpp:2199
#8  0x000000000239d88e in optimizeGlobalsInModule(llvm::Module&,
llvm::DataLayout const&,
llvm::TargetLibraryInfo*, llvm::function_ref<llvm::DominatorTree&
(llvm::Function&)>) (M=...,
DL=..., TLI=0x8293860, LookupDomTree=...)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/Transforms/IPO/GlobalOpt.cpp:2655
#9  0x00000000023a9f8c in (anonymous
namespace)::GlobalOptLegacyPass::runOnModule
(this=0x8294f10, M=...)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/Transforms/IPO/GlobalOpt.cpp:2705
#10 0x00000000022ac02a in (anonymous namespace)::MPPassManager::runOnModule
(this=0x831de40, M=...)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/IR/LegacyPassManager.cpp:1603
#11 0x00000000022abb56 in llvm::legacy::PassManagerImpl::run (this=0x83237d0,
M=...)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/IR/LegacyPassManager.cpp:1706
#12 0x00000000022ac541 in llvm::legacy::PassManager::run (this=0x7fffffffb500,
M=...)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/lib/IR/LegacyPassManager.cpp:1737
#13 0x0000000002adf7c5 in (anonymous
namespace)::EmitAssemblyHelper::EmitAssembly
(this=0x7fffffffb7a8, Action=clang::Backend_EmitObj, OS=...)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/lib/CodeGen/BackendUtil.cpp:734
#14 0x0000000002adeda6 in clang::EmitBackendOutput (Diags=..., CGOpts=...,
TOpts=...,
LOpts=..., TDesc=..., M=0x82b1f90,
      Action=clang::Backend_EmitObj, OS=...)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/lib/CodeGen/BackendUtil.cpp:751
#15 0x00000000035d622f in clang::BackendConsumer::HandleTranslationUnit
(this=0x82b1a80, C=...)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/lib/CodeGen/CodeGenAction.cpp:179
#16 0x0000000004259504 in clang::ParseAST (S=..., PrintStats=false,
SkipFunctionBodies=false)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/lib/Parse/ParseAST.cpp:167
#17 0x00000000030f011a in clang::ASTFrontendAction::ExecuteAction
(this=0x8297f20)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/lib/Frontend/FrontendAction.cpp:556
#18 0x00000000035d4bf5 in clang::CodeGenAction::ExecuteAction (this=0x8297f20)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/lib/CodeGen/CodeGenAction.cpp:853
#19 0x00000000030efc00 in clang::FrontendAction::Execute (this=0x8297f20)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/lib/Frontend/FrontendAction.cpp:457
#20 0x0000000003094c81 in clang::CompilerInstance::ExecuteAction
(this=0x827df40, Act=...)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/lib/Frontend/CompilerInstance.cpp:867
#21 0x0000000003241ba1 in clang::ExecuteCompilerInvocation (Clang=0x827df40)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/lib/FrontendTool/ExecuteCompilerInvocation.cpp:241
#22 0x0000000000c33bc8 in cc1_main (Argv=...,
      Argv0=0x7fffffffe3f9 
"/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/tmp/clang",
      MainAddr=0xc26010 <GetExecutablePath(char const*, bool)>)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/tools/driver/cc1_main.cpp:116
#23 0x0000000000c27c2a in ExecuteCC1Tool (argv=..., Tool=...)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/tools/driver/driver.cpp:301
#24 0x0000000000c26ae2 in main (argc_=52, argv_=0x7fffffffdfb8)
      at 
/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/llvm/tools/cfe/tools/driver/driver.cpp:382








----- /tmp/main_with_3_globals-841619.c -----

# 1 "<built-in>"
# 1 "main_with_3_globals.c"
int  foo;
char bar;
long baz;

int main(){return foo;}



----- /tmp/main_with_3_globals-841619.sh -----

# Crash reproducer for clang version 3.9.0
# Driver args: "main_with_3_globals.c" "-O3"
# Original command: 
"/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/build_003/bin/clang-3.9"
"-cc1" "-triple" "x86_64-unknown-linux-gnu"
"-emit-obj" "-disable-free" "-main-file-name"
"main_with_3_globals.c" "-mrelocation-model"
"static" "-mthread-model" "posix"
"-fmath-errno"
"-masm-verbose" "-mconstructor-aliases"
"-munwind-tables" "-fuse-init-array" "-target-cpu"
"x86-64" "-momit-leaf-frame-pointer"
"-dwarf-column-info" "-debugger-tuning=gdb"
"-resource-dir" 
"/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/build_003/bin/../lib/clang/3.9.0"
"-internal-isystem" "/usr/local/include"
"-internal-isystem"
"/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/build_003/bin/../lib/clang/3.9.0/include"
"-internal-externc-isystem" "/usr/include/x86_64-linux-gnu"
"-internal-externc-isystem"
"/include" "-internal-externc-isystem"
"/usr/include" "-O3" "-fdebug-compilation-dir"
"/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/tmp"
"-ferror-limit" "19" "-fmessage-length"
"144" "-fobjc-runtime=gcc"
"-fdiagnostics-show-option"
"-fcolor-diagnostics" "-vectorize-loops"
"-vectorize-slp" "-o"
"/tmp/main_with_3_globals-cef92e.o" "-x" "c"
"main_with_3_globals.c"
 
"/work/Abe/non-backup-worthy/build_dirs/Clang/pre-3.9/2016-07-17-22-54-42-1cb1a4c-master/build_003/bin/clang-3.9"
"-cc1" "-triple" "x86_64-unknown-linux-gnu"
"-emit-obj" "-disable-free" "-main-file-name"
"main_with_3_globals.c" "-mrelocation-model"
"static" "-mthread-model" "posix"
"-fmath-errno"
"-masm-verbose" "-mconstructor-aliases"
"-munwind-tables" "-fuse-init-array" "-target-cpu"
"x86-64" "-momit-leaf-frame-pointer"
"-dwarf-column-info" "-debugger-tuning=gdb" "-O3"
"-ferror-limit" "19" "-fmessage-length"
"144" "-fobjc-runtime=gcc"
"-fdiagnostics-show-option"
"-fcolor-diagnostics" "-vectorize-loops"
"-vectorize-slp" "-x" "c"
"main_with_3_globals-841619.c"






[the previous 3 sections, i.e. error dump + preprocessed C code + shell code:
much the same
with an AArch64 target, using "-target aarch64-gnu-linux" and
containing the output line
"Target: aarch64--linux-gnu"]