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add pre-processing simplificaiton of power to the legacy simplifier Fixes #1237

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-08-28 00:05:53 -07:00
parent 5db349f6fa
commit 8542e4ae3d
2 changed files with 21 additions and 1 deletions
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21
src/ast/simplifier/arith_simplifier_plugin.cpp
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@ -402,7 +402,7 @@ bool arith_simplifier_plugin::reduce(func_decl * f, unsigned num_args, expr * co
case OP_TO_REAL: SASSERT(num_args == 1); mk_to_real(args[0], result); break;
case OP_TO_INT: SASSERT(num_args == 1); mk_to_int(args[0], result); break;
case OP_IS_INT: SASSERT(num_args == 1); mk_is_int(args[0], result); break;
case OP_POWER: return false;
case OP_POWER: SASSERT(num_args == 2); mk_power(args[0], args[1], result); break;
case OP_ABS: SASSERT(num_args == 1); mk_abs(args[0], result); break;
case OP_IRRATIONAL_ALGEBRAIC_NUM: return false;
default:
@ -412,6 +412,25 @@ bool arith_simplifier_plugin::reduce(func_decl * f, unsigned num_args, expr * co
return true;
}
void arith_simplifier_plugin::mk_power(expr* x, expr* y, expr_ref& result) {
rational a, b;
if (is_numeral(y, b) && b.is_one()) {
result = x;
return;
}
if (is_numeral(x, a) && is_numeral(y, b) && b.is_unsigned()) {
if (b.is_zero() && !a.is_zero()) {
result = m_util.mk_numeral(rational(1), m_manager.get_sort(x));
return;
}
if (!b.is_zero()) {
result = m_util.mk_numeral(power(a, b.get_unsigned()), m_manager.get_sort(x));
return;
}
}
result = m_util.mk_power(x, y);
}
void arith_simplifier_plugin::mk_abs(expr * arg, expr_ref & result) {
expr_ref c(m_manager);
expr_ref m_arg(m_manager);

1
src/ast/simplifier/arith_simplifier_plugin.h
View file

@ -82,6 +82,7 @@ public:
void mk_to_real(expr * arg, expr_ref & result);
void mk_to_int(expr * arg, expr_ref & result);
void mk_is_int(expr * arg, expr_ref & result);
void mk_power(expr* x, expr* y, expr_ref& result);
void mk_abs(expr * arg, expr_ref & result);
virtual bool reduce(func_decl * f, unsigned num_args, expr * const * args, expr_ref & result);