Jeffrey A Law wrote:
> For example, if the only use was inside an unreachable hunk of
> code, does that count as a use or not?
Yes, the EDG front-end does this:
[EMAIL PROTECTED]:~/tmp$ cat test.cpp
void f() {
int i;
if (0)
i = 3;
}
[EMAIL PROTECTED]:~/tmp$ eccp -A test.cpp
"test.cpp", line 2: warning: variable "i" was set but never used
int i;
^
(The "SGI Compiler" used to be EDG-based, on IRIX. I don't know whether
Kaveh's referring to that version or to the Open64 version, based on the
GCC front ends.)
(Wouldn't it be easy to emit a warning for this in GCC, in the same
optimization-based way we do uninitialized warnings? If there are no
paths from the block with the assignment to a use, then the store is
useless.)
I don't think EDG even builds a CFG. I think they just use some
relatively conservative algorithms to produce these sorts of warnings.
For this:
int i;
l:
j = i; // j is global
if (0)
i = 3;
goto l;
they don't warn on the unintialized use of "i"; they probably treat i as
maybe-initialized before reaching j.
So, just as you would expect, they are more consistent across the
various parameters we've discussed, but less accurate.
--
Mark Mitchell
CodeSourcery, LLC
[EMAIL PROTECTED]
(916) 791-8304
