[Bug c/18624] GCC does not detect local variable set but never used

[dcb314 at hotmail dot com]

------- Comment #14 from dcb314 at hotmail dot com  2009-06-11 12:57 -------
(In reply to comment #13)

> We need someone to write the patch. Just that.

I've got some spare time now, so I'd like to have a go.

I can see that used_flag bitfield can be expanded from 1 bit to 2 bits.
I can see that TREE_USED macro can be reworked to match. 

What concerns me is all the different places (currently 170) that the
text pattern "TREE_USED.*=" occurs.

I suspect a manual review of each of those 170 places would be 
prone to failure. Even without considering the various languages
in sub directories, there are still 84 uses of "TREE_USED.*=" left.

Considering solely the test program I originally posted, how
would I go about finding which subset of the 84 places get 
visited by the test program ?

gdb with 84 breakpoints doesn't sound feasible to me.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18624