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fp.isNegative does not handle NaN properly #13

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LeventErkok opened this issue Mar 29, 2015 · 1 comment
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fp.isNegative does not handle NaN properly #13

LeventErkok opened this issue Mar 29, 2015 · 1 comment
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@wintersteiger

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@LeventErkok
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This is on the unstable branch.

For this benchmark:

(set-option :produce-models true)
(set-logic QF_FP)
(declare-fun s0 () (_ FloatingPoint 11 53))
(assert
   (let ((s1 (and (fp.isNaN s0) (fp.isNegative s0))))
   s1))
(check-sat)
(get-value (s0))

Z3 produces:

sat
((s0 (_ NaN 11 53)))

Which suggests NaN is accepted by the predicate fp.isNegative. According to the formalization, fp.isNegative holds for -0.0 and when the number lt compares to 0 successfully, neither of which is true for NaN.
LeventErkok added a commit to LeventErkok/sbv that referenced this issue Mar 29, 2015
@LeventErkok
Add fp-classifiers
961e40b 
This partially addresses #132. Unfortunately a bunch of tests are
failing for these tests due to issues in Z3. In particular, see:
Z3Prover/z3#13 and
Z3Prover/z3#10

Until those bugs are resolved on the z3 side these predicates should be
used with care!
@LeventErkok LeventErkok mentioned this issue Mar 29, 2015
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@wintersteiger wintersteiger self-assigned this Mar 29, 2015
wintersteiger referenced this issue in wintersteiger/z3 Mar 29, 2015
@wintersteiger
Bugfix for fp.isNegative.
0ed16c0 
Fixes #13
wintersteiger added a commit that referenced this issue Mar 29, 2015
@wintersteiger
Merge pull request #15 from wintersteiger/unstable
4a0eb93 
Integrating fixes for #10, #13, #14
@wintersteiger
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Fixed in unstable, thanks again!

@itszor itszor mentioned this issue Jun 1, 2015
Closed
wintersteiger referenced this issue in wintersteiger/z3 Oct 5, 2015
@AleksandarZeljic
Merge pull request #13 from wintersteiger/smallFloats
ce8f0ac 
Smallfloats model generation fixes.
NikolajBjorner referenced this issue in NikolajBjorner/z3 Jun 1, 2016
@levnach
Merge pull request #13 from NikolajBjorner/lev
f6d51f3 
Bug fixes to theory_lra, exposes now an issue with strictness models
@NikolajBjorner NikolajBjorner mentioned this issue Sep 29, 2016
Merged
@qingkaishi qingkaishi mentioned this issue Nov 21, 2016
Closed
@NikolajBjorner NikolajBjorner mentioned this issue Jul 1, 2017
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This was referenced Jan 31, 2018
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@levnach levnach mentioned this issue Nov 28, 2018
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mtzguido added a commit to mtzguido/z3 that referenced this issue Jun 23, 2023
@mtzguido
bool_rewriter: fix possible segfault when disabling rewriter.sort_dis…
ccd828e 
…junctions

After introducing the rewriter.sort_disjunctions option, I noticed a
segfault in a Z3 run that was working fine for me.

I traced the difference to a slight discrepancy between the first patch
I submitted and the one we ended up merging: my first version would skip
sorting the disjuncts in mk_nflat_core, but still return BR_DONE, while
the patch in master returns BR_FAILED instead.

This patch fixes the problem for me, and it makes slightly more sense
to me to return a BR_DONE since, if `s` is true, some disjunct (e.g. a
`false` or a repeat) might have been simplified away. However I don't
fully understand this code.

.. and I can't say I understand why the segfault happens. Perhaps that
is a separate issue?

This is the file to reproduce:
 https://gist.github.com/mtzguido/b7360c74d3d2e42d89f1bd9149ad26f6

Here's a stack trace of the failure, mk_nflat_or_core is not involved.
```
 (gdb) where
 #0  0x0000555555b98497 in smt::context::get_lit_assignment(unsigned int) const ()
 Z3Prover#1  0x0000555555b984cb in smt::context::get_assignment(sat::literal) const ()
 Z3Prover#2  0x0000555555b98504 in smt::context::get_assignment(unsigned int) const ()
 Z3Prover#3  0x0000555555ca83b8 in smt::context::get_assignment_core(expr*) const ()
 Z3Prover#4  0x0000555555c9af5a in smt::context::get_assignment(expr*) const ()
 Z3Prover#5  0x0000555555d7bd1d in (anonymous namespace)::has_child_assigned_to(smt::context&, app*, lbool, expr*&, unsigned int) ()
 Z3Prover#6  0x0000555555d7c413 in (anonymous namespace)::rel_case_split_queue::next_case_split_core(ptr_vector<expr>&, unsigned int&, unsigned int&, lbool&) ()
 Z3Prover#7  0x0000555555d7c589 in (anonymous namespace)::rel_case_split_queue::next_case_split(unsigned int&, lbool&) ()
 Z3Prover#8  0x0000555555c9c1b7 in smt::context::decide() ()
 Z3Prover#9  0x0000555555ca39fd in smt::context::bounded_search() ()
 Z3Prover#10 0x0000555555ca30c2 in smt::context::search() ()
 Z3Prover#11 0x0000555555ca273d in smt::context::check(unsigned int, expr* const*, bool) ()
 Z3Prover#12 0x0000555555cb166a in smt::kernel::check(unsigned int, expr* const*) ()
 Z3Prover#13 0x0000555555cb9695 in (anonymous namespace)::smt_solver::check_sat_core2(unsigned int, expr* const*) ()
 Z3Prover#14 0x00005555560dc0c6 in solver_na2as::check_sat_core(unsigned int, expr* const*) ()
 Z3Prover#15 0x00005555560d73f3 in combined_solver::check_sat_core(unsigned int, expr* const*) ()
 Z3Prover#16 0x00005555560d34e3 in solver::check_sat(unsigned int, expr* const*) ()
 Z3Prover#17 0x0000555556097b26 in cmd_context::check_sat(unsigned int, expr* const*) ()
 Z3Prover#18 0x0000555556082ff0 in smt2::parser::parse_check_sat() ()
 Z3Prover#19 0x0000555556084dc0 in smt2::parser::parse_cmd() ()
 Z3Prover#20 0x00005555560861b6 in smt2::parser::operator()() ()
 Z3Prover#21 0x00005555560757e6 in parse_smt2_commands(cmd_context&, std::basic_istream<char, std::char_traits<char> >&, bool, params_ref const&, char const*) ()
 Z3Prover#22 0x00005555555e8f68 in read_smtlib2_commands(char const*) ()
 Z3Prover#23 0x00005555555ee6f6 in main ()
 (gdb)
```
mtzguido added a commit to mtzguido/z3 that referenced this issue Jun 23, 2023
@mtzguido
bool_rewriter: fix possible segfault when disabling rewriter.sort_dis…
c9c5f1e 
…junctions

After introducing the rewriter.sort_disjunctions option (Z3Prover#6774), I
noticed a segfault in a Z3 run that was working fine for me before the
PR.

I traced the difference to a slight discrepancy between the first patch
I submitted and the one we ended up merging: my first version would skip
sorting the disjuncts in mk_nflat_core, but still return BR_DONE, while
the patch in master returns BR_FAILED instead.

This patch fixes that problem, and it makes slightly more sense to me to
return a BR_DONE since, if `s` is true, some disjunct (e.g. a `false`
or a repeat) might have been simplified away. However I don't fully
understand this code.

... and I can't say I understand why the segfault happens. Perhaps that
is a separate issue?

This is the file to reproduce:
 https://gist.github.com/mtzguido/b7360c74d3d2e42d89f1bd9149ad26f6

Here's a stack trace of the failure, mk_nflat_or_core is not involved.
```
 (gdb) where
 #0  0x0000555555b98497 in smt::context::get_lit_assignment(unsigned int) const ()
 Z3Prover#1  0x0000555555b984cb in smt::context::get_assignment(sat::literal) const ()
 Z3Prover#2  0x0000555555b98504 in smt::context::get_assignment(unsigned int) const ()
 Z3Prover#3  0x0000555555ca83b8 in smt::context::get_assignment_core(expr*) const ()
 Z3Prover#4  0x0000555555c9af5a in smt::context::get_assignment(expr*) const ()
 Z3Prover#5  0x0000555555d7bd1d in (anonymous namespace)::has_child_assigned_to(smt::context&, app*, lbool, expr*&, unsigned int) ()
 Z3Prover#6  0x0000555555d7c413 in (anonymous namespace)::rel_case_split_queue::next_case_split_core(ptr_vector<expr>&, unsigned int&, unsigned int&, lbool&) ()
 Z3Prover#7  0x0000555555d7c589 in (anonymous namespace)::rel_case_split_queue::next_case_split(unsigned int&, lbool&) ()
 Z3Prover#8  0x0000555555c9c1b7 in smt::context::decide() ()
 Z3Prover#9  0x0000555555ca39fd in smt::context::bounded_search() ()
 Z3Prover#10 0x0000555555ca30c2 in smt::context::search() ()
 Z3Prover#11 0x0000555555ca273d in smt::context::check(unsigned int, expr* const*, bool) ()
 Z3Prover#12 0x0000555555cb166a in smt::kernel::check(unsigned int, expr* const*) ()
 Z3Prover#13 0x0000555555cb9695 in (anonymous namespace)::smt_solver::check_sat_core2(unsigned int, expr* const*) ()
 Z3Prover#14 0x00005555560dc0c6 in solver_na2as::check_sat_core(unsigned int, expr* const*) ()
 Z3Prover#15 0x00005555560d73f3 in combined_solver::check_sat_core(unsigned int, expr* const*) ()
 Z3Prover#16 0x00005555560d34e3 in solver::check_sat(unsigned int, expr* const*) ()
 Z3Prover#17 0x0000555556097b26 in cmd_context::check_sat(unsigned int, expr* const*) ()
 Z3Prover#18 0x0000555556082ff0 in smt2::parser::parse_check_sat() ()
 Z3Prover#19 0x0000555556084dc0 in smt2::parser::parse_cmd() ()
 Z3Prover#20 0x00005555560861b6 in smt2::parser::operator()() ()
 Z3Prover#21 0x00005555560757e6 in parse_smt2_commands(cmd_context&, std::basic_istream<char, std::char_traits<char> >&, bool, params_ref const&, char const*) ()
 Z3Prover#22 0x00005555555e8f68 in read_smtlib2_commands(char const*) ()
 Z3Prover#23 0x00005555555ee6f6 in main ()
 (gdb)
```
NikolajBjorner pushed a commit that referenced this issue Jun 23, 2023
@mtzguido
bool_rewriter: fix possible segfault when disabling rewriter.sort_dis…
7c380fd 
…junctions (#6779)

After introducing the rewriter.sort_disjunctions option (#6774), I
noticed a segfault in a Z3 run that was working fine for me before the
PR.

I traced the difference to a slight discrepancy between the first patch
I submitted and the one we ended up merging: my first version would skip
sorting the disjuncts in mk_nflat_core, but still return BR_DONE, while
the patch in master returns BR_FAILED instead.

This patch fixes that problem, and it makes slightly more sense to me to
return a BR_DONE since, if `s` is true, some disjunct (e.g. a `false`
or a repeat) might have been simplified away. However I don't fully
understand this code.

... and I can't say I understand why the segfault happens. Perhaps that
is a separate issue?

This is the file to reproduce:
 https://gist.github.com/mtzguido/b7360c74d3d2e42d89f1bd9149ad26f6

Here's a stack trace of the failure, mk_nflat_or_core is not involved.
```
 (gdb) where
 #0  0x0000555555b98497 in smt::context::get_lit_assignment(unsigned int) const ()
 #1  0x0000555555b984cb in smt::context::get_assignment(sat::literal) const ()
 #2  0x0000555555b98504 in smt::context::get_assignment(unsigned int) const ()
 #3  0x0000555555ca83b8 in smt::context::get_assignment_core(expr*) const ()
 #4  0x0000555555c9af5a in smt::context::get_assignment(expr*) const ()
 #5  0x0000555555d7bd1d in (anonymous namespace)::has_child_assigned_to(smt::context&, app*, lbool, expr*&, unsigned int) ()
 #6  0x0000555555d7c413 in (anonymous namespace)::rel_case_split_queue::next_case_split_core(ptr_vector<expr>&, unsigned int&, unsigned int&, lbool&) ()
 #7  0x0000555555d7c589 in (anonymous namespace)::rel_case_split_queue::next_case_split(unsigned int&, lbool&) ()
 #8  0x0000555555c9c1b7 in smt::context::decide() ()
 #9  0x0000555555ca39fd in smt::context::bounded_search() ()
 #10 0x0000555555ca30c2 in smt::context::search() ()
 #11 0x0000555555ca273d in smt::context::check(unsigned int, expr* const*, bool) ()
 #12 0x0000555555cb166a in smt::kernel::check(unsigned int, expr* const*) ()
 #13 0x0000555555cb9695 in (anonymous namespace)::smt_solver::check_sat_core2(unsigned int, expr* const*) ()
 #14 0x00005555560dc0c6 in solver_na2as::check_sat_core(unsigned int, expr* const*) ()
 #15 0x00005555560d73f3 in combined_solver::check_sat_core(unsigned int, expr* const*) ()
 #16 0x00005555560d34e3 in solver::check_sat(unsigned int, expr* const*) ()
 #17 0x0000555556097b26 in cmd_context::check_sat(unsigned int, expr* const*) ()
 #18 0x0000555556082ff0 in smt2::parser::parse_check_sat() ()
 #19 0x0000555556084dc0 in smt2::parser::parse_cmd() ()
 #20 0x00005555560861b6 in smt2::parser::operator()() ()
 #21 0x00005555560757e6 in parse_smt2_commands(cmd_context&, std::basic_istream<char, std::char_traits<char> >&, bool, params_ref const&, char const*) ()
 #22 0x00005555555e8f68 in read_smtlib2_commands(char const*) ()
 #23 0x00005555555ee6f6 in main ()
 (gdb)
```
@rammohan02 rammohan02 mentioned this issue Feb 10, 2024
Closed
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@LeventErkok @wintersteiger