Hi,
I just noticed a change between 6.7 and 6.8 in how gdb handles the
implicit type of some large constants. I have the following script:
$ cat gdb-regtest-1
set $foo = (1 << 46)-1
p/x $foo
file ~/prog/c/misc/sizeof
p/x $foo
set $foo = (1 << 46)-1
p/x $foo
"sizeof" is a dummy program which does nothing fancy. It is however worth
noting that it's a native x86-64 binary, ie. the platform I'm running on.
So if I feed gdb-6.7 with the script above, I see this:
$ ./gdb-6.7/gdb/gdb -batch -x gdb-regtest-1
$1 = 0xffffffff
Using host libthread_db library "/lib/libthread_db.so.1".
$2 = 0xffffffff
$3 = 0x3fffffffffff
So setting $foo before and after loading the binary gives different
results!
Now with gdb-6.8:
$ ./gdb-6.8/gdb/gdb -batch -x gdb-regtest-1
$1 = 0xffffffff
$2 = 0xffffffff
$3 = 0xffffffff
At least this looks consistent, except that it's not the value I want for
my constant $foo.
Now I try again my test, this time with a cast into a long:
$ cat gdb-regtest-2
set $foo = ((long)1 << 46)-1
p/x $foo
file ~/prog/c/misc/sizeof
p/x $foo
set $foo = ((long)1 << 46)-1
p/x $foo
Then gdb-6.8 shows inconsistent results again:
$ ./gdb-6.8/gdb/gdb -batch -x gdb-regtest-2
$1 = 0xffffffff
$2 = 0xffffffff
$3 = 0x3fffffffffff
This looks definitely wrong to me.
--
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