PR analyzer/93352 reports a qsort failure "comparator not anti-symmetric: -2147483648, -2147483648)" within the analyzer on code involving an array access of [0x7fffffff + 1].
The issue is that array_region (which uses int for keys into known values in the array) uses subtraction to implement int_cmp for sorting the keys, which isn't going to work for boundary values. Potentially a wider type should be used, but for now this patch fixes the ICE by using explicit comparisons rather than subtraction to implement the qsort callback. Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu; pushed to master as r10-6127-g4f01e5778689977c9569477947b8062d8d866667. gcc/analyzer/ChangeLog: PR analyzer/93352 * region-model.cc (int_cmp): Rename to... (array_region::key_cmp): ...this, using key_t rather than int. Rewrite in terms of comparisons rather than subtraction to ensure qsort is anti-symmetric when handling extreme values. (array_region::walk_for_canonicalization): Update for above renaming. * region-model.h (array_region::key_cmp): New decl. gcc/testsuite/ChangeLog: PR analyzer/93352 * gcc.dg/analyzer/pr93352.c: New test. --- gcc/analyzer/region-model.cc | 19 ++++++++++++------- gcc/analyzer/region-model.h | 2 ++ gcc/testsuite/gcc.dg/analyzer/pr93352.c | 12 ++++++++++++ 3 files changed, 26 insertions(+), 7 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/analyzer/pr93352.c diff --git a/gcc/analyzer/region-model.cc b/gcc/analyzer/region-model.cc index 7e995701dce..0bca5c0fd71 100644 --- a/gcc/analyzer/region-model.cc +++ b/gcc/analyzer/region-model.cc @@ -2389,15 +2389,20 @@ array_region::get_key_for_child_region (region_id child_rid, key_t *out) const return false; } -/* qsort comparator for int. */ +/* qsort comparator for array_region's keys. */ -static int -int_cmp (const void *p1, const void *p2) +int +array_region::key_cmp (const void *p1, const void *p2) { - int i1 = *(const int *)p1; - int i2 = *(const int *)p2; + key_t i1 = *(const key_t *)p1; + key_t i2 = *(const key_t *)p2; - return i1 - i2; + if (i1 > i2) + return 1; + else if (i1 < i2) + return -1; + else + return 0; } /* Implementation of region::walk_for_canonicalization vfunc for @@ -2414,7 +2419,7 @@ array_region::walk_for_canonicalization (canonicalization *c) const int key_a = (*iter).first; keys.quick_push (key_a); } - keys.qsort (int_cmp); + keys.qsort (key_cmp); unsigned i; int key; diff --git a/gcc/analyzer/region-model.h b/gcc/analyzer/region-model.h index 6a63a9336b8..1090b96bfaa 100644 --- a/gcc/analyzer/region-model.h +++ b/gcc/analyzer/region-model.h @@ -1375,6 +1375,8 @@ public: static key_t key_from_constant (tree cst); private: + static int key_cmp (const void *, const void *); + /* Mapping from tree to child region. */ map_t m_map; }; diff --git a/gcc/testsuite/gcc.dg/analyzer/pr93352.c b/gcc/testsuite/gcc.dg/analyzer/pr93352.c new file mode 100644 index 00000000000..ccb96d0eaed --- /dev/null +++ b/gcc/testsuite/gcc.dg/analyzer/pr93352.c @@ -0,0 +1,12 @@ +/* { dg-additional-options "-Wno-overflow" } */ + +struct yc { + int c0; + char di[]; +}; + +void +qt (struct yc *ab) +{ + ab->di[0x7fffffff + 1] = ab->di[0]; +} -- 2.21.0