[Bug ada/15851] New: pragma Volatile not respected for variables with default value

[Bug ada/15851] New: pragma Volatile not respected for variables with default value

[jc at apinc dot org]

In the following code, there is no generated code for testing wether v1 is 
really equals to v2, even with the pragma Volatile:
with Ada.Text_IO; use Ada.Text_IO;

procedure bug_volatile is

  v1 : Integer := 0;
  v2 : Integer := 0;
  pragma Volatile (v1);
  pragma Volatile (v2);
begin
  if v1 = v2 then
    Put_Line ("v1 = v2");
  end if;
  delay 1.0;
  if v1 = v2 then
    Put_Line ("v1 = v2");
  end if;         
end bug_volatile;

Neither the first nor the second test are made. I believe both test should be 
made, since the values might have been modified by an external event (another 
process, another task, hardware, ...) and this is why we made them "volatile".
An equivalent C code actually generates both tests.

GCC version:
Reading specs from /usr/lib/gcc/i486-linux/3.4.0/specs
Configured with: ../src/configure -v --enable-languages=c,c++,java,f77,pascal,
objc,ada,treelang --prefix=/usr --libexecdir=/usr/lib 
--with-gxx-include-dir=/usr/include/c++/3.4 --enable-shared --with-system-zlib 
--enable-nls --enable-threads=posix --without-included-gettext 
--program-suffix=-3.4 --enable-__cxa_atexit --enable-clocale=gnu 
--enable-libstdcxx-debug --enable-java-gc=boehm --enable-java-awt=gtk 
--disable-werror i486-linux
Thread model: posix
gcc version 3.4.0 (Debian 20040516)

Program was compiled with:
gcc -S bug_volatile.adb
and
gcc -O2 -S bug_volatile.adb

Both commands don't generate code for the tests.
If I didn't give default value, oviously tests are made. However with a warning 
during compilation about v1 and v2 never assigned a value. Again this might be 
an incorrect warning since we explicitly made variables volatiles, so they *may* 
be assigned a value by something else (well, probably giving a warning is 
better).

Regards,
JC

-- 
           Summary: pragma Volatile not respected for variables with default
                    value
           Product: gcc
           Version: 3.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: ada
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jc at apinc dot org
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i486-pc-linux-gnu
  GCC host triplet: i486-pc-linux-gnu
GCC target triplet: i486-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15851

[Bug ada/15851] pragma Volatile not respected for variables with default value

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15851

[Bug ada/15851] pragma Volatile not respected for variables with default value

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-01 01:37 -------
Confirmed.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2004-11-01 01:37:55
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15851