Module: ppl/ppl Branch: master Commit: c8cbb00f29ac4c0d48daf14a9a9d3b93e559e207 URL: http://www.cs.unipr.it/git/gitweb.cgi?p=ppl/ppl.git;a=commit;h=c8cbb00f29ac4...

Author: Patricia Hill p.m.hill@leeds.ac.uk Date: Wed May 13 09:21:47 2009 +0100

Fixed a bug in wrap_assign() for grids.

---

src/Grid_public.cc | 22 +++++++++++-------- tests/Grid/wrap1.cc | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 69 insertions(+), 9 deletions(-)

diff --git a/src/Grid_public.cc b/src/Grid_public.cc index 844c7ec..16e6ba9 100644 --- a/src/Grid_public.cc +++ b/src/Grid_public.cc @@ -2700,6 +2700,7 @@ PPL::Grid::wrap_assign(const Variables_Set& vars, PPL_DIRTY_TEMP_COEFFICIENT(f_d); PPL_DIRTY_TEMP_COEFFICIENT(v_n); PPL_DIRTY_TEMP_COEFFICIENT(v_d); + PPL_DIRTY_TEMP_COEFFICIENT(f_d_wrap_frequency); for (Variables_Set::const_iterator i = vars.begin(), vars_end = vars.end(); i != vars.end(); ++i) { const Variable x = Variable(*i); @@ -2730,9 +2731,16 @@ PPL::Grid::wrap_assign(const Variables_Set& vars, }

// `x' is not a constant in `gr'. - if (2*f_n > f_d * wrap_frequency) { - // If the grid frequency for `x' in `vars' is more than half the - // `wrap_frequency', then `x' can only take a unique (ie constant) + assert(f_n != 0); + Coefficient& wrap_modulus = f_n; + f_d_wrap_frequency = f_d * wrap_frequency; + if (o == OVERFLOW_WRAPS && f_n != f_d * wrap_frequency) + // We know that `x' is not a constant, so, if overflow wraps, + // `x' may wrap to a value modulo the `wrap_frequency'. + add_grid_generator(parameter(wrap_frequency * x)); + else if ((o == OVERFLOW_IMPOSSIBLE && 2*f_n >= f_d_wrap_frequency) + || (f_n == f_d_wrap_frequency)) { + // In these cases, `x' can only take a unique (ie constant) // value. if (s == UNSIGNED && v_n < 0) { // `v_n' is the value closest to 0 and may be negative. @@ -2742,16 +2750,12 @@ PPL::Grid::wrap_assign(const Variables_Set& vars, } add_constraint(v_d * x == v_n); } - else if (o == OVERFLOW_WRAPS) - // We know that `x' is not a constant, so, if overflow wraps, - // `x' may wrap to a value modulo the `wrap_frequency'. - add_grid_generator(parameter(wrap_frequency * x)); else - // If overflow is impossible but the grid frequency is no more than + // If overflow is impossible but the grid frequency is less than // half the wrap frequency, then there is more than one possible // value for `x' in the range of the bounded integer type, // so the grid is unchanged. - assert(o == OVERFLOW_IMPOSSIBLE && 2*f_n <= f_d * wrap_frequency); + assert(o == OVERFLOW_IMPOSSIBLE && 2*f_n < f_d_wrap_frequency); } return; } diff --git a/tests/Grid/wrap1.cc b/tests/Grid/wrap1.cc index 235ba02..cf45a97 100644 --- a/tests/Grid/wrap1.cc +++ b/tests/Grid/wrap1.cc @@ -352,6 +352,60 @@ test13() { return ok; }

+bool +test14() { + Variable x(0); + Variable y(1); + + Grid gr1(2); + gr1.add_congruence((x %= 245) / 255); + Grid gr2(gr1); + + Variables_Set vars(x); + + gr1.wrap_assign(vars, BITS_8, UNSIGNED, OVERFLOW_WRAPS); + gr2.wrap_assign(vars, BITS_8, SIGNED_2_COMPLEMENT, OVERFLOW_WRAPS); + + Grid known_result1(2); + known_result1.add_congruence((x %= 0) / 1); + Grid known_result2(2); + known_result2.add_congruence((x %= 0) / 1); + + bool ok = (gr1 == known_result1 && gr2 == known_result2); + + print_congruences(gr1, "*** gr1.wrap_assign(...) ***"); + print_congruences(gr2, "*** gr2.wrap_assign(...) ***"); + + return ok; +} + +bool +test15() { + Variable x(0); + Variable y(1); + + Grid gr1(2); + gr1.add_congruence((x %= 245) / 256); + Grid gr2(gr1); + + Variables_Set vars(x); + + gr1.wrap_assign(vars, BITS_8, UNSIGNED, OVERFLOW_WRAPS); + gr2.wrap_assign(vars, BITS_8, SIGNED_2_COMPLEMENT, OVERFLOW_WRAPS); + + Grid known_result1(2); + known_result1.add_congruence((x %= 245) / 0); + Grid known_result2(2); + known_result2.add_congruence((x %= -11) / 0); + + bool ok = (gr1 == known_result1 && gr2 == known_result2); + + print_congruences(gr1, "*** gr1.wrap_assign(...) ***"); + print_congruences(gr2, "*** gr2.wrap_assign(...) ***"); + + return ok; +} +

} // namespace

@@ -369,4 +423,6 @@ BEGIN_MAIN DO_TEST_F8(test11); DO_TEST_F8(test12); DO_TEST_F8(test13); + DO_TEST_F8(test14); + DO_TEST_F8(test15); END_MAIN