Sparse has a warning -Wptr-subtraction-blows (off by default) which generates a warning for any pointer subtractions. This warning relates to GCC shortcomings observed in 2005; the original log message: > commit 6889bd0f84939675c743229d6fe623513b95e057 > Author: Linus Torvalds <[email protected]> > Date: Fri Jan 7 15:06:24 2005 -0700 > > Add option "-Wptr-subtraction-blows" to warn about expensive > pointer subtractions. > > Not only does it generate bad code (that can often be rewritten > to not do that), it also causes gcc to go into horrible contortions, > and Al Viro reports that it can make a factor of 2.5 difference in > kernel build times to have just a few of these in common header > file inline functions. Does this still apply? Do current versions of GCC still have this problem? If not, can the option and warning go away? - Josh Triplett
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