[LLVMbugs] [Bug 13768] New: C++ exceptions are not catched on ARM (core is dumped)

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=13768

             Bug #: 13768
           Summary: C++ exceptions are not catched on ARM (core is dumped)
           Product: new-bugs
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: liangh at quicinc.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified


Created attachment 9157
  --> http://llvm.org/bugs/attachment.cgi?id=9157
assembly and IR dump

LLVM can not generate correct code for exception handling on ARM. Core is
dumped at run-time. Please see below for the testcase "throw.cpp".

#######################
## src:
#######################
include <iostream>
using namespace std;                                                            

int foo(){
  throw -15;
}

int main () {
  try{
    foo();
    cout <<"Should not be here" << endl;
  }
  catch(...){
    cout <<" Exception caught" << endl;
  }

}

#######################
## compile-1:
####################### 
clang++  -mfloat-abi=softfp -mfpu=neon -ccc-gcc-name  arm-cross-g++ -o throw
-O0 throw.cpp

## run result:
terminate called after throwing an instance of 'int'
Aborted (core dumped)

## Stack:
Program received signal SIGABRT, Aborted.
0x00069590 in raise ()
#1  0x00069790 in abort ()
#2  0x00048ff8 in __gnu_cxx::__verbose_terminate_handler() ()
#3  0x00048ba8 in __cxxabiv1::__terminate(void (*)()) ()
#4  0x00048bd0 in std::terminate() ()
#5  0x00046988 in __cxa_throw ()
#6  0x00008f04 in foo () at throw.cpp:5
#######################

The problem is that the catch-related calls are missing in the assembly. Please
see attached "throw.s". With "-print-after-all", we can see that all
catch-related calls are removed by the pass "Remove unreachable blocks from the
CFG". Please see attached "throw.print"

By adding the flag "-mllvm -arm-enable-ehabi", the catch-related code is kept
in assembly, but the executable still abort with a core dumped. Please see
below and the attached "throw-ehabi.s" and "throw-ehabi.print" for details.

#######################
## compile-2 (-mllvm -arm-enable-ehabi):
####################### 
clang++  -mfloat-abi=softfp -mfpu=neon -ccc-gcc-name  arm-cross-g++ -o throw
-O0 -mllvm -arm-enable-ehabi throw.cpp

## run result:
Aborted (core dumped)

## Stack:
Program received signal SIGABRT, Aborted.
0x00069620 in raise ()
#1  0x00069820 in abort ()
#2  0x00060c40 in _Unwind_GetDataRelBase ()
#3  0x00048574 in __gxx_personality_v0 ()
#4  0x0006010c in __gnu_Unwind_RaiseException ()
#5  0x000603d4 in ___Unwind_RaiseException ()
#6  0x00046a08 in __cxa_throw ()
#7  0x00008f04 in foo () at throw.cpp:5
#######################

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