A lot of simplifications are only valid when their variables satisfy to some conditions (like "is within a given range" or "is a power of two"). So, allow to add such pre-conditions via new _assume() statements. Internally, all such preconditions are ANDed together and what is checked is they imply the assertions: AND(pre-condition) implies assertion 1 ... Note: IIUC, it seems that boolector has a native mechanism for such things but I'm not sure if t can be used here. Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx> --- ident-list.h | 1 + scheck.c | 33 ++++++++++++++++++++++++--------- validation/scheck/ok.c | 6 ++++++ 3 files changed, 31 insertions(+), 9 deletions(-) diff --git a/ident-list.h b/ident-list.h index 6264fd062534..3c08e8ca9aa4 100644 --- a/ident-list.h +++ b/ident-list.h @@ -79,6 +79,7 @@ IDENT(copy_to_user); IDENT(copy_from_user); IDENT(main); /* used by the symbolic checker */ +IDENT(__assume); IDENT(__assert); IDENT(__assert_eq); IDENT(__assert_const); diff --git a/scheck.c b/scheck.c index ff140aaa1e95..b8bc9bb28498 100644 --- a/scheck.c +++ b/scheck.c @@ -31,6 +31,7 @@ #define dyntype incomplete_ctype static const struct builtin_fn builtins_scheck[] = { + { "__assume", &void_ctype, 0, { &dyntype }, .op = &generic_int_op }, { "__assert", &void_ctype, 0, { &bool_ctype }, .op = &generic_int_op }, { "__assert_eq", &void_ctype, 0, { &dyntype, &dyntype }, .op = &generic_int_op }, { "__assert_const", &void_ctype, 0, { &dyntype, &dyntype }, .op = &generic_int_op }, @@ -184,11 +185,22 @@ static void ternop(Btor *btor, struct instruction *insn) insn->target->priv = t; } -static bool check_btor(Btor *btor, BoolectorNode *n, struct instruction *insn) +static bool add_precondition(Btor *btor, BoolectorNode **pre, struct instruction *insn) +{ + BoolectorNode *a = get_arg(btor, insn, 0); + BoolectorNode *z = boolector_zero(btor, boolector_get_sort(btor, a)); + BoolectorNode *n = boolector_ne(btor, a, z); + BoolectorNode *p = boolector_and(btor, *pre, n); + *pre = p; + return true; +} + +static bool check_btor(Btor *btor, BoolectorNode *p, BoolectorNode *n, struct instruction *insn) { char model_format[] = "btor"; int res; + n = boolector_implies(btor, p, n); boolector_assert(btor, boolector_not(btor, n)); res = boolector_sat(btor); switch (res) { @@ -207,20 +219,20 @@ static bool check_btor(Btor *btor, BoolectorNode *n, struct instruction *insn) return 0; } -static bool check_assert(Btor *btor, struct instruction *insn) +static bool check_assert(Btor *btor, BoolectorNode *pre, struct instruction *insn) { BoolectorNode *a = get_arg(btor, insn, 0); BoolectorNode *z = boolector_zero(btor, boolector_get_sort(btor, a)); BoolectorNode *n = boolector_ne(btor, a, z); - return check_btor(btor, n, insn); + return check_btor(btor, pre, n, insn); } -static bool check_equal(Btor *btor, struct instruction *insn) +static bool check_equal(Btor *btor, BoolectorNode *pre, struct instruction *insn) { BoolectorNode *a = get_arg(btor, insn, 0); BoolectorNode *b = get_arg(btor, insn, 1); BoolectorNode *n = boolector_eq(btor, a, b); - return check_btor(btor, n, insn); + return check_btor(btor, pre, n, insn); } static bool check_const(Btor *ctxt, struct instruction *insn) @@ -239,15 +251,17 @@ static bool check_const(Btor *ctxt, struct instruction *insn) return 0; } -static bool check_call(Btor *btor, struct instruction *insn) +static bool check_call(Btor *btor, BoolectorNode **pre, struct instruction *insn) { pseudo_t func = insn->func; struct ident *ident = func->ident; + if (ident == &__assume_ident) + return add_precondition(btor, pre, insn); if (ident == &__assert_ident) - return check_assert(btor, insn); + return check_assert(btor, *pre, insn); if (ident == &__assert_eq_ident) - return check_equal(btor, insn); + return check_equal(btor, *pre, insn); if (ident == &__assert_const_ident) return check_const(btor, insn); return 0; @@ -256,6 +270,7 @@ static bool check_call(Btor *btor, struct instruction *insn) static bool check_function(struct entrypoint *ep) { Btor *btor = boolector_new(); + BoolectorNode *pre = boolector_true(btor); struct basic_block *bb; int rc = 0; @@ -281,7 +296,7 @@ static bool check_function(struct entrypoint *ep) ternop(btor, insn); break; case OP_CALL: - rc &= check_call(btor, insn); + rc &= check_call(btor, &pre, insn); break; case OP_RET: goto out; diff --git a/validation/scheck/ok.c b/validation/scheck/ok.c index 8f65013e1618..1e5314f24ded 100644 --- a/validation/scheck/ok.c +++ b/validation/scheck/ok.c @@ -10,6 +10,12 @@ static void always(int x) __assert((x - x) == 0); // true and simplified } +static void assumed(int x, int a, int b) +{ + __assume((a & ~b) == 0); + __assert_eq((x ^ a) | b, x | b); +} + /* * check-name: scheck-ok * check-command: scheck $file -- 2.31.1