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remove buggy code, close, fix #5825

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
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Nikolaj Bjorner 2022-03-20 13:25:44 -07:00
parent 1e8bae01e9
commit f1806d32d6
1 changed files with 5 additions and 14 deletions
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19
src/ast/rewriter/seq_rewriter.cpp
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@ -936,22 +936,13 @@ expr_ref seq_rewriter::mk_seq_last(expr* t) {
} }
/* /*
* In general constructs substring(t,0,|t|-1) but if t = substring(s,0,k) then simplifies to substring(s,0,k-1) * In general constructs substring(t,0,|t|-1)
* This method assumes that |t| > 0, thus, if t = substring(s,0,k) then k > 0 so substring(s,0,k-1) is correct. * Incorrect comment: "but if t = substring(s,0,k) then simplifies to substring(s,0,k-1).
* This method assumes that |t| > 0, thus, if t = substring(s,0,k) then k > 0 so substring(s,0,k-1) is correct."
* No: if k > |s| then substring(s,0,k) = substring(s,0,k-1)
*/ */
expr_ref seq_rewriter::mk_seq_butlast(expr* t) { expr_ref seq_rewriter::mk_seq_butlast(expr* t) {
expr_ref result(m()); return expr_ref(str().mk_substr(t, zero(), m_autil.mk_sub(str().mk_length(t), one())), m());
expr* s, * j, * k;
rational v;
if (false && str().is_extract(t, s, j, k) && m_autil.is_numeral(j, v) && v.is_zero()) {
expr_ref_vector k_min_1(m());
k_min_1.push_back(k);
k_min_1.push_back(minus_one());
result = str().mk_substr(s, j, m_autil.mk_add_simplify(k_min_1));
}
else
result = str().mk_substr(t, zero(), m_autil.mk_sub(str().mk_length(t), one()));
return result;
} }
/* /*