[LLVMbugs] [Bug 18688] New: clang crashes on valid code at -O3 on x86_64-linux-gnu

Fri Jan 31 21:54:06 PST 2014

http://llvm.org/bugs/show_bug.cgi?id=18688

            Bug ID: 18688
           Summary: clang crashes on valid code at -O3 on x86_64-linux-gnu
           Product: clang
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: -New Bugs
          Assignee: unassignedclangbugs at nondot.org
          Reporter: su at cs.ucdavis.edu
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

The current clang trunk crashes when compiling the following testcase at -O3 in
both 32-bit and 64-bit modes on x86_64-linux-gnu. 

This is a regression from clang 3.4. 

$ clang-trunk -v
clang version 3.5 (trunk 200521)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.1
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
$ 
$ clang-trunk -O2 -c small.c
$ clang-3.4 -O3 -c small.c
$ 
$ clang-trunk -O3 -c small.c
clang: /tmp/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp:394: virtual bool
<anonymous namespace>::LoopUnswitch::runOnLoop(llvm::Loop *,
llvm::LPPassManager &): Assertion `currentLoop->isLCSSAForm(*DT)' failed.
0  clang           0x0000000002362165 llvm::sys::PrintStackTrace(_IO_FILE*) +
37
1  clang           0x0000000002362953
2  libpthread.so.0 0x00007fdabd22ccb0
3  libc.so.6       0x00007fdabc04a425 gsignal + 53
4  libc.so.6       0x00007fdabc04db8b abort + 379
5  libc.so.6       0x00007fdabc0430ee
6  libc.so.6       0x00007fdabc043192
7  clang           0x0000000001f6098b
8  clang           0x000000000212c310
llvm::LPPassManager::runOnFunction(llvm::Function&) + 944
9  clang           0x0000000002277184
llvm::FPPassManager::runOnFunction(llvm::Function&) + 356
10 clang           0x00000000020a13c5
11 clang           0x00000000022779a7
llvm::legacy::PassManagerImpl::run(llvm::Module&) + 999
12 clang           0x0000000000872413
clang::EmitBackendOutput(clang::DiagnosticsEngine&, clang::CodeGenOptions
const&, clang::TargetOptions const&, clang::LangOptions const&,
llvm::StringRef, llvm::Module*, clang::BackendAction, llvm::raw_ostream*) +
6579
13 clang           0x000000000086fd99
14 clang           0x00000000009fc5e3 clang::ParseAST(clang::Sema&, bool, bool)
+ 515
15 clang           0x000000000086ebbe clang::CodeGenAction::ExecuteAction() +
142
16 clang           0x00000000006ce3d0 clang::FrontendAction::Execute() + 112
17 clang           0x00000000006aad8d
clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) + 925
18 clang           0x0000000000691410
clang::ExecuteCompilerInvocation(clang::CompilerInstance*) + 2896
19 clang           0x0000000000688fe4 cc1_main(char const**, char const**, char
const*, void*) + 692
20 clang           0x000000000068dba7 main + 3431
21 libc.so.6       0x00007fdabc03576d __libc_start_main + 237
22 clang           0x0000000000688c49
Stack dump:
0.    Program arguments: /usr/local/clang-trunk/bin/clang -cc1 -triple
x86_64-unknown-linux-gnu -emit-obj -disable-free -main-file-name small.c
-mrelocation-model static -fmath-errno -masm-verbose -mconstructor-aliases
-munwind-tables -fuse-init-array -target-cpu x86-64 -target-linker-version 2.22
-momit-leaf-frame-pointer -coverage-file
/data2/c-hunter-results/C/trans-bugs/REPORTED/20131210-clang-m32-m64-O3-wrong-test308654/run-crash/small.o
-resource-dir /usr/local/clang-trunk/bin/../lib/clang/3.5 -internal-isystem
/usr/local/include -internal-isystem
/usr/local/clang-trunk/bin/../lib/clang/3.5/include -internal-externc-isystem
/usr/include/x86_64-linux-gnu -internal-externc-isystem /include
-internal-externc-isystem /usr/include -O3 -fdebug-compilation-dir
/data2/c-hunter-results/C/trans-bugs/REPORTED/20131210-clang-m32-m64-O3-wrong-test308654/run-crash
-ferror-limit 19 -fmessage-length 122 -mstackrealign -fobjc-runtime=gcc
-fdiagnostics-show-option -fcolor-diagnostics -vectorize-loops -vectorize-slp
-o small.o -x c small.c 
1.    <eof> parser at end of file
2.    Per-module optimization passes
3.    Running pass 'CallGraph Pass Manager' on module 'small.c'.
4.    Running pass 'Loop Pass Manager' on function '@foo'
5.    Running pass 'Unswitch loops' on basic block '%for.body3.us11'
clang: error: unable to execute command: Aborted (core dumped)
clang: error: clang frontend command failed due to signal (use -v to see
invocation)
clang version 3.5 (trunk 200521)
Target: x86_64-unknown-linux-gnu
Thread model: posix
clang: 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: note: diagnostic msg: 
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang: note: diagnostic msg: /tmp/small-347c1a.c
clang: note: diagnostic msg: /tmp/small-347c1a.sh
clang: note: diagnostic msg: 

********************
$

----------------------------

int a, b, c, d;

void
foo ()
{
  for (; a;)
    {
      b = 0;
      for (; c;)
        d || (b = 0);
    }
}

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