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Implement proposed smtlib2 bitvector overflow predicates (#6715)

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* Logical names for function declarations in c++

Currently, for example, the function declaration symbol member for
checking whether multiplication *does not* overflow is called
`m_bv_smul_ovfl`.  Since we are introducing the upcoming smtlib2 symbols
that check that multpliciation *does* overflow, the not overflow check
symbols are renamed to `m_bv_smul_no_ovfl` etc.

* Implement smtlib overflow preds for multiplication

Smtlib2 is being extended to include overflow predicates for bit
vectors (see https://groups.google.com/u/1/g/smt-lib/c/J4D99wT0aKI).
This commit introduces the predicates `bvumulo` and `bvsmulo` that
return `true` if the unsigned multiplication overflows or the signed
multiplication underflows or overflows, respectively.

* Move mul overflow predicates to BV logic

* Add a todo on illogical argument order

* Implement mk_unary_pred for bv

* Implement bvnego

* Implement bvuaddo

* Implement bvsaddo

* Implement bvusubo

* Implement bvssubo

* Implement bvsdivo
This commit is contained in:
Antti Hyvärinen 2023-05-09 19:37:46 +02:00 • committed by GitHub
parent 62e1ec0698
commit 12e45c9d17
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4 changed files with 222 additions and 7 deletions
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16
src/ast/rewriter/bv_rewriter.h
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@ -139,6 +139,22 @@ class bv_rewriter : public poly_rewriter<bv_rewriter_core> {
br_status mk_mkbv(unsigned num, expr * const * args, expr_ref & result);
br_status mk_bvsmul_no_overflow(unsigned num, expr * const * args, bool is_overflow, expr_ref & result);
br_status mk_bvumul_no_overflow(unsigned num, expr * const * args, expr_ref & result);
br_status mk_bvsmul_overflow(unsigned num, expr * const * args, expr_ref & result);
br_status mk_bvumul_overflow(unsigned num, expr * const * args, expr_ref & result);
br_status mk_bvsdiv_overflow(unsigned num, expr * const * args, expr_ref & result);
br_status mk_bvneg_overflow(expr * const arg, expr_ref & result);
br_status mk_bvuadd_overflow(unsigned num, expr * const * args, expr_ref & result);
br_status mk_bvsadd_overflow(unsigned num, expr * const * args, expr_ref & result);
br_status mk_bvsadd_underflow(unsigned num, expr * const * args, expr_ref & result);
br_status mk_bvsadd_over_underflow(unsigned num, expr * const * args, expr_ref & result);
br_status mk_bvusub_underflow(unsigned num, expr * const * args, expr_ref & result);
br_status mk_bvssub_overflow(unsigned num, expr * const * args, expr_ref & result);
bool is_minus_one_times_t(expr * arg);
void mk_t1_add_t2_eq_c(expr * t1, expr * t2, expr * c, expr_ref & result);