[Bug c++/23702] New: volatile const members of structures not treated as volatile

[Bug c++/23702] New: volatile const members of structures not treated as volatile

[Steve at Zook dot com]

Volatile const members of a struct are not generating a load when read while 
volatile non-const members are loaded (volatile const objects outside of a 
structure do generate a load when read). const members of a volatile struct 
generate two loads when read (strange code being produced in this case). This 
has been seen in 3.3.3 (for x86 and m68k targets) and 3.4.4 (for m68k targets, 
untested on x86). The attached test.cpp file when compiled gcc -c -save-temps 
test.cpp on 3.3.3 under cygwin (x86 target) produces the attached test.s 
output. Multiple stores on volatile const members of structs get optimized 
away as well (this is not demonstrated in the attached test code). Note that 
when the test code is compiled as C rather than C++, correct code gets 
produced.

-- 
           Summary: volatile const members of structures not treated as
                    volatile
           Product: gcc
           Version: 3.4.4
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: Steve at Zook dot com
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23702

[Bug c++/23702] volatile const members of structures not treated as volatile

[Steve at Zook dot com]

------- Additional Comments From Steve at Zook dot com  2005-09-02 19:33 -------
Created an attachment (id=9652)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=9652&action=view)
Test code


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23702

[Bug c++/23702] volatile const members of structures not treated as volatile

[Steve at Zook dot com]

------- Additional Comments From Steve at Zook dot com  2005-09-02 19:36 -------
Created an attachment (id=9653)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=9653&action=view)
Sample compiled output for test code

This sample was compiled:
gcc -c -save-temps test.cpp
on rev 3.3.3 under Cygwin

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23702

[Bug c++/23702] volatile const members of structures not treated as volatile

[Steve at Zook dot com]

------- Additional Comments From Steve at Zook dot com  2005-09-19 20:06 -------
Test using i686-pc-cygwin with revision 4.0.1 shows problem resolved and good 
code being emitted (although two new warnings are output about non-local 
anonymous variables).

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23702

[Bug c++/23702] volatile const members of structures not treated as volatile

[bangerth at gmail dot com]

------- Comment #4 from bangerth at gmail dot com  2009-08-25 13:59 -------
gcc 3.3 has not been maintained for a long time. Since you say that gcc 4.0
fixes the bug, I think we can close the bug.

W.


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bangerth at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bangerth at gmail dot com
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23702