[Bug other/28917] New: try/catch block removed. too optimistic optimization?

[Bug other/28917] New: try/catch block removed. too optimistic optimization?

[pluto at agmk dot net]

with fixed PR26208 we can throw exceptions from signal handlers.
catch() works pretty fine with complex call-chain but fails on
simple testcase.

#include <csignal>
void signalHandler( int signalNumber )
{
        throw 0;
}
int main()
{
        signal( SIGSEGV, signalHandler );
        try
        {
                int* p = 0;
                *p = 0;
        }
        catch ( int )
        {
        }
        return 0;
}

$ g++ throw_from_sighandler.cpp -O1 --save-temps && ./a.out
terminate called after throwing an instance of 'int'
zsh: abort      ./a.out

main:
        subq    $8, %rsp
        movl    $_Z13signalHandleri, %esi
        movl    $11, %edi
        call    signal
        movl    $0, 0
        movl    $0, %eax
        addq    $8, %rsp
        ret


-- 
           Summary: try/catch block removed. too optimistic optimization?
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pluto at agmk dot net
GCC target triplet: x86-64-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28917

[Bug other/28917] try/catch block removed. too optimistic optimization?

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2006-08-31 19:08 -------
I think you forgot "-fnon-call-exceptions" which is need to be used if you want
non calls to be able to throw.
Can you try with that option and report if that fixes the problem?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28917

[Bug other/28917] try/catch block removed. too optimistic optimization?

[pluto at agmk dot net]

------- Comment #2 from pluto at agmk dot net  2006-08-31 19:13 -------
it doesn't help. `jmp .L2` skips catch block :)

main:
        pushq   %rbx
        movl    $_Z13signalHandleri, %esi
        movl    $11, %edi
        call    signal
        movl    $0, 0
        jmp     .L2
.L8:
        cmpq    $1, %rdx
        je      .L3
        movq    %rax, %rdi
        call    _Unwind_Resume
.L3:
        movq    %rax, %rdi
        call    __cxa_begin_catch
        movl    (%rax), %eax
        call    __cxa_end_catch
        jmp     .L2
.L7:
        movq    %rax, %rbx
.L4:
        call    __cxa_end_catch
        movq    %rbx, %rdi
        call    _Unwind_Resume
.L2:
        movl    $0, %eax
        popq    %rbx
        ret


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28917

[Bug rtl-optimization/28917] try/catch block removed. too optimistic optimization?

[pinskia at gcc dot gnu dot org]

------- Comment #3 from pinskia at gcc dot gnu dot org  2006-08-31 19:27 -------
Actually yes it is branched because it should be but         movl    $0, 0

Means store 0 into the address of 0 so it works.  The branch over is ok because
well this is the way zero overhead exceptions works.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
          Component|other                       |rtl-optimization
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28917