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* [Bug c++/57693] New: The program logically failed in case of used "int b += b++"
@ 2013-06-24 7:46 vlad94009277 at gmail dot com
2013-06-24 7:49 ` [Bug c++/57693] " pinskia at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: vlad94009277 at gmail dot com @ 2013-06-24 7:46 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57693
Bug ID: 57693
Summary: The program logically failed in case of used "int b +=
b++"
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: major
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: vlad94009277 at gmail dot com
Steps to reproduce:
1. Write the following source cod and compile it:
#include <iostream>
using namespace std;
int main(){
int d = 7;
int c = 7;
int &b = c;
b += b++;
d += d++;
cout << "c = "<< c << endl;
cout << "d = "<< d << endl;
return 0;
}
2. Run the appropriate generated executable file.
Actual result:
It's printed:
c = 8
d = 15
Expected result:
It should be printed:
c = 15
d = 15
Please note that there are different assemble codes for used operators:
1) d += d++
movl -4(%rbp), %eax // Copies value of d to register %eax
addl %eax, %eax // Adds %eax to %eax, remembers the value in %eax
movl %eax, -4(%rbp) // Moves %eax to d (d = 14)
addl $1, -4(%rbp) // Increments the value of d (d = 15)
2) b += b++
movl -12(%rbp), %eax // Moves the value of b to %eax
movl -12(%rbp), %edx // Moves the value of b to %edx
leal (%rax,%rdx), %edx // Adds %rax to %rdx and stores result in %edx (%rax and
%rdx are equal to 7, so after this operation %edx is 14)
movl %edx, -12(%rbp) // Moves %edx to d (d = 14)
addl $1, %eax // Increments the value of %eax (%eax = 8).
movl %eax, -12(%rbp) // Moves %eax to d (d = 8)
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/57693] The program logically failed in case of used "int b += b++"
2013-06-24 7:46 [Bug c++/57693] New: The program logically failed in case of used "int b += b++" vlad94009277 at gmail dot com
@ 2013-06-24 7:49 ` pinskia at gcc dot gnu.org
2013-06-24 8:15 ` vlad94009277 at gmail dot com
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2013-06-24 7:49 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57693
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |INVALID
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Both:
b += b++;
And
d += d++;
are undefined what value b and d is going to be as there are no sequence point
intbetween the two assignments.
They could be:
temp = b;
b++;
b += temp;
or b++;
b+=b;
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/57693] The program logically failed in case of used "int b += b++"
2013-06-24 7:46 [Bug c++/57693] New: The program logically failed in case of used "int b += b++" vlad94009277 at gmail dot com
2013-06-24 7:49 ` [Bug c++/57693] " pinskia at gcc dot gnu.org
@ 2013-06-24 8:15 ` vlad94009277 at gmail dot com
2013-06-24 8:18 ` jakub at gcc dot gnu.org
2013-06-24 10:05 ` manu at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: vlad94009277 at gmail dot com @ 2013-06-24 8:15 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57693
--- Comment #2 from Vladimir <vlad94009277 at gmail dot com> ---
(In reply to Andrew Pinski from comment #1)
> Both:
> b += b++;
> And
> d += d++;
>
> are undefined what value b and d is going to be as there are no sequence
> point intbetween the two assignments.
>
> They could be:
> temp = b;
> b++;
> b += temp;
>
> or b++;
> b+=b;
I tried this issue on version 4.8.1 and it works successfully.
It seems the bug was already fixed.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/57693] The program logically failed in case of used "int b += b++"
2013-06-24 7:46 [Bug c++/57693] New: The program logically failed in case of used "int b += b++" vlad94009277 at gmail dot com
2013-06-24 7:49 ` [Bug c++/57693] " pinskia at gcc dot gnu.org
2013-06-24 8:15 ` vlad94009277 at gmail dot com
@ 2013-06-24 8:18 ` jakub at gcc dot gnu.org
2013-06-24 10:05 ` manu at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: jakub at gcc dot gnu.org @ 2013-06-24 8:18 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57693
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jakub at gcc dot gnu.org
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
You are not listening, the only bug here is in your testcase, not in the
compiler.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/57693] The program logically failed in case of used "int b += b++"
2013-06-24 7:46 [Bug c++/57693] New: The program logically failed in case of used "int b += b++" vlad94009277 at gmail dot com
` (2 preceding siblings ...)
2013-06-24 8:18 ` jakub at gcc dot gnu.org
@ 2013-06-24 10:05 ` manu at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: manu at gcc dot gnu.org @ 2013-06-24 10:05 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57693
Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |manu at gcc dot gnu.org
--- Comment #4 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
> Both:
> b += b++;
> And
> d += d++;
>
> are undefined what value b and d is going to be as there are no sequence
> point intbetween the two assignments.
>
> They could be:
> temp = b;
> b++;
> b += temp;
>
> or b++;
> b+=b;
Please, could we make more use of the FAQ?
http://gcc.gnu.org/wiki/FAQ#undefinedbut
If you think the answer does not provide enough information, just extend the
answer there. (it could mention some example, and -Wsequence-points).
Otherwise, we have the same back and forth over and over again to the
frustration of users and the time waste of developers: what is UB? but my
program worked before! but my program works without optimizations! but I know
how it should work! can't gcc be consistent? but UB should not affect my
problem! I think this should not be UB!
>From gcc-bugs-return-424969-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Mon Jun 24 10:15:22 2013
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From: "burnus at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug fortran/57696] New: Defined assignment for components not used when those are ALLOCATABLE
Date: Mon, 24 Jun 2013 10:15:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idW696
Bug ID: 57696
Summary: Defined assignment for components not used when those
are ALLOCATABLE
Product: gcc
Version: 4.9.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: burnus at gcc dot gnu.org
CC: pault at gcc dot gnu.org
The following prints
42
42
with gfortran and
42
20
with crayftn. Thus, gfortran does not use defined assignment - but it should.
Note: If "right%foo" is not allocated, the code segfaults with crayftn.
module m0
implicit none
type component
integer :: i = 42
contains
procedure :: assign0
generic :: assignment(=) => assign0
end type
type parent
type(component), allocatable :: foo
end type
contains
elemental subroutine assign0(lhs,rhs)
class(component), intent(INout) :: lhs
class(component), intent(in) :: rhs
lhs%i = 20
end subroutine
end module
program main
use m0
implicit none
type(parent) :: left, right
allocate(right%foo)
print *, right%foo
left = right
print *, left%foo
end
^ permalink raw reply [flat|nested] 5+ messages in thread
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-- links below jump to the message on this page --
2013-06-24 7:46 [Bug c++/57693] New: The program logically failed in case of used "int b += b++" vlad94009277 at gmail dot com
2013-06-24 7:49 ` [Bug c++/57693] " pinskia at gcc dot gnu.org
2013-06-24 8:15 ` vlad94009277 at gmail dot com
2013-06-24 8:18 ` jakub at gcc dot gnu.org
2013-06-24 10:05 ` manu at gcc dot gnu.org
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