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analyzer: fix qsort issue with array_region keys (PR 93352)

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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.

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.
This commit is contained in:
David Malcolm 2020-01-21 12:42:36 -05:00
parent c77074d056
commit 4f01e57786
5 changed files with 42 additions and 7 deletions
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11
gcc/analyzer/ChangeLog
View File

@ -1,3 +1,14 @@
2020-01-21 David Malcolm <dmalcolm@redhat.com>
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.
2020-01-17 David Malcolm <dmalcolm@redhat.com>
PR analyzer/93290

19
gcc/analyzer/region-model.cc
View File

@ -2387,15 +2387,20 @@ 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
@ -2412,7 +2417,7 @@ 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;

2
gcc/analyzer/region-model.h
View File

@ -1319,6 +1319,8 @@ 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;
};

5
gcc/testsuite/ChangeLog
View File

@ -1,3 +1,8 @@
2020-01-21 David Malcolm <dmalcolm@redhat.com>
PR analyzer/93352
* gcc.dg/analyzer/pr93352.c: New test.
2020-01-22 Hans-Peter Nilsson <hp@axis.com>
* gcc.target/cris/asm-v8.S, gcc.target/cris/inasm-v8.c,

12
gcc/testsuite/gcc.dg/analyzer/pr93352.c Normal file
View File

@ -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];
}