[LLVMbugs] [Bug 14177] New: Incorrect eh context when throwing expression, which throws exception itself

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=14177

             Bug #: 14177
           Summary: Incorrect eh context when throwing expression, which
                    throws exception itself
           Product: clang
           Version: trunk
          Platform: Macintosh
        OS/Version: MacOS X
            Status: NEW
          Severity: normal
          Priority: P
         Component: C++
        AssignedTo: unassignedclangbugs at nondot.org
        ReportedBy: a.bataev at gmx.com
                CC: dgregor at apple.com, llvmbugs at cs.uiuc.edu
    Classification: Unclassified


The following simple test should terminate (calling std::terminate), but it
catches the exception thrown in the copy constructor due to incorrect code
generated by clang:

#include <stdio.h>

struct C
{
    C() { }
    C(const C&) { throw 0; }
};

int main()
{
    try
    {
        C cc;
        throw cc;  // should call std::terminate()
    }
    catch(int) {puts("caught int");}
    catch(C)  {puts("caught C");}
}

Here is llvm bitcode corresponding to throwing exception:

invoke.cont:                                      ; preds = %entry
  %exception = call i8* @__cxa_allocate_exception(i64 1) nounwind
  %2 = bitcast i8* %exception to %struct.C*
  invoke void @_ZN1CC1ERKS_(%struct.C* %2, %struct.C* %cc)
          to label %invoke.cont2 unwind label %lpad1

invoke.cont2:                                     ; preds = %invoke.cont
  invoke void @__cxa_throw(i8* %exception, i8* bitcast ({ i8*, i8* }* @_ZTI1C
to i8*), i8* null) noreturn
          to label %unreachable unwind label %lpad

lpad:                                             ; preds = %invoke.cont2,
%entry
  %3 = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)*
@__gxx_personality_v0 to i8*)
          catch i8* bitcast (i8** @_ZTIi to i8*)
          catch i8* bitcast ({ i8*, i8* }* @_ZTI1C to i8*)
  %4 = extractvalue { i8*, i32 } %3, 0
  store i8* %4, i8** %exn.slot
  %5 = extractvalue { i8*, i32 } %3, 1
  store i32 %5, i32* %ehselector.slot
  br label %catch.dispatch

lpad1:                                            ; preds = %invoke.cont
  %6 = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)*
@__gxx_personality_v0 to i8*)
          cleanup
          catch i8* bitcast (i8** @_ZTIi to i8*)
          catch i8* bitcast ({ i8*, i8* }* @_ZTI1C to i8*)
  %7 = extractvalue { i8*, i32 } %6, 0
  store i8* %7, i8** %exn.slot
  %8 = extractvalue { i8*, i32 } %6, 1
  store i32 %8, i32* %ehselector.slot
  call void @__cxa_free_exception(i8* %exception) nounwind
  br label %catch.dispatch

A call to copy constructor should be in a terminate context, but it's not
(unwind edge points to the incorrect landingpad %lpad1).

Alexey Bataev
Software Engineer
Intel Compiler Team
Intel Corp.

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