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Merge pull request #1337 from mtrberzi/fix-length-testing

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Optimizations for length testing in theory_str
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Nikolaj Bjorner 2017-10-30 12:00:47 -07:00 • committed by GitHub
commit 29d643cc23
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2 changed files with 26 additions and 1 deletions
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2
src/smt/params/smt_params_helper.pyg
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@ -74,7 +74,7 @@ def_module_params(module_name='smt',
('str.fast_length_tester_cache', BOOL, False, 'cache length tester constants instead of regenerating them'),
('str.fast_value_tester_cache', BOOL, True, 'cache value tester constants instead of regenerating them'),
('str.string_constant_cache', BOOL, True, 'cache all generated string constants generated from anywhere in theory_str'),
('str.use_binary_search', BOOL, False, 'use a binary search heuristic for finding concrete length values for free variables in theory_str (set to False to use linear search)'),
('str.use_binary_search', BOOL, True, 'use a binary search heuristic for finding concrete length values for free variables in theory_str (set to False to use linear search)'),
('str.binary_search_start', UINT, 64, 'initial upper bound for theory_str binary search'),
('theory_aware_branching', BOOL, False, 'Allow the context to use extra information from theory solvers regarding literal branching prioritization.'),
('str.finite_overlap_models', BOOL, False, 'attempt a finite model search for overlapping variables instead of completely giving up on the arrangement'),

25
src/smt/theory_str.cpp
View file

@ -9907,6 +9907,21 @@ namespace smt {
expr_ref freeVarLen(mk_strlen(freeVar), m);
SASSERT(freeVarLen);
{
rational freeVar_len_value;
if (get_len_value(freeVar, freeVar_len_value)) {
TRACE("str", tout << "special case: length of freeVar is known to be " << freeVar_len_value << std::endl;);
expr_ref concreteOption(ctx.mk_eq_atom(indicator, mk_string(freeVar_len_value.to_string().c_str()) ), m);
expr_ref concreteValue(ctx.mk_eq_atom(
ctx.mk_eq_atom(indicator, mk_string(freeVar_len_value.to_string().c_str()) ),
ctx.mk_eq_atom(freeVarLen, m_autil.mk_numeral(freeVar_len_value, true))), m);
expr_ref finalAxiom(m.mk_and(concreteOption, concreteValue), m);
SASSERT(finalAxiom);
m_trail.push_back(finalAxiom);
return finalAxiom;
}
}
expr_ref_vector orList(m);
expr_ref_vector andList(m);
@ -10221,6 +10236,16 @@ namespace smt {
}
refresh_theory_var(firstTester);
{
rational freeVar_len_value;
if (get_len_value(freeVar, freeVar_len_value)) {
TRACE("str", tout << "special case: length of freeVar is known to be " << freeVar_len_value << std::endl;);
midPoint = freeVar_len_value;
upperBound = midPoint * 2;
windowSize = upperBound;
}
}
binary_search_len_tester_stack[freeVar].push_back(firstTester);
m_trail_stack.push(binary_search_trail<theory_str>(binary_search_len_tester_stack, freeVar));
binary_search_info new_info(lowerBound, midPoint, upperBound, windowSize);