Hi guys,
I'm trying to use watchpoints to detect user-space reads/writes of an
arbitrary C/C++ program variable.
For example:
void foo() {
int x; // <-- I'm interested in 'x'
x = 10; // <-- I want to detect this
for (int i = 0; i < 4; ++i) {
x = i; // <-- And this
bar(x);
}
x = 20; // <-- and this
bar(x);
baz( &x ); // <-- and any updates to 'x' during this call
}
My concern is that the clang+LLVM will sometimes model "x" using a
register or constant, rather than with memory. And so a watchpoint
might miss some reads/writes to "x".
Does anyone know of a way to minimize or eliminate this problem?
Ideas I've considered so far:
* Compiling the whole program with "-O0". This might be enough, but
I'm not sure.
* Add the "volatile" qualifier to "x". This might solve the problem,
but could require countless additions of "volatile" elsewhere as well.
* Adding a statement of the form "my_dummy_func( &x )". Assuming this
reliably causes a memory allocation for "x", this might help. But I
wouldn't expect it to reliably preclude "x"'s value from being modeled
with a register or constant at certain locations in the object code.
I don't mind modifying compiler/linker flags, but I'd prefer to not
modify the source code. I should be able to use most versions of GCC
and/or Clang/LLVM/LLDB.
Thanks,
Christian
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