region_model.cc's tree_cmp attempted to verify that the ordering
is symmetric by asserting that
tree_cmp (x, y) == -tree_cmp (y, x)
This condition is too strong: it's only required for a comparator that
sign (tree_cmp (x, y)) == -sign (tree_cmp (y, x))
and the incorrect form of the assertion doesn't hold e.g. on s390x where
for certain inputs x, y, tree_cmp (x, y) == 1 and tree_cmp (y, x) == -2,
breaking the build in "make selftest" in stage1.
In any case, these checks are redundant, since qsort_chk performs them.
Additionally, there is a potential lack of transitivity in
worklist::key_t::cmp where hashval_t values are compared by subtraction,
which could fail to be transitive if overflows occur.
This patch eliminates the redundant checks and reimplements the hashval_t
comparisons in terms of < and >, fixing these issues.
gcc/analyzer/ChangeLog:
* call-string.cc (call_string::cmp_1): Delete, moving body to...
(call_string::cmp): ...here.
* call-string.h (call_string::cmp_1): Delete decl.
* engine.cc (worklist::key_t::cmp_1): Delete, moving body to...
(worklist::key_t::cmp): ...here. Implement hash comparisons
via comparison rather than subtraction to avoid overflow issues.
* exploded-graph.h (worklist::key_t::cmp_1): Delete decl.
* region-model.cc (tree_cmp): Eliminate buggy checking for
symmetry.
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