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Add support for optimizing exists-forall problems.

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Modifies smt2 backend to recognize `$anyconst` etc. assigned to a wire with the `maximize` or `minimize` attribute and emit `; yosys-smt2-maximize` or `; yosys-smt2-minimize` directives as appropriate.
Modifies `backends/smt2/smtbmc.py` and `smtio.py` to recognize those directives and emit a `(maximize ...)` or `(minimize ...)` command at the end of `smt_forall_assert()`, as described in the paper "νZ - An Optimizing SMT Solver" by Nikolaj Bjørner et al.
Adds an example `examples/smtbmc/demo9.v` to show how it can be used.
This commit is contained in:
Alberto Gonzalez 2020-03-08 06:34:47 +00:00
parent bfeba9ad11
commit 0fda8308bc
5 changed files with 55 additions and 3 deletions
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14
backends/smt2/smtbmc.py
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@ -1158,6 +1158,8 @@ def smt_forall_assert():
global asserts_cache_dirty
asserts_cache_dirty = False
assert (len(smt.modinfo[topmod].maximize) + len(smt.modinfo[topmod].minimize) <= 1)
def make_assert_expr(asserts_cache):
expr = list()
for lst in asserts_cache:
@ -1236,6 +1238,18 @@ def smt_forall_assert():
smt.write("".join(assert_expr))
if len(smt.modinfo[topmod].maximize) > 0:
for s in states:
if s in used_states_db:
smt.write("(maximize (|%s| %s))\n" % (smt.modinfo[topmod].maximize.copy().pop(), s))
break
if len(smt.modinfo[topmod].minimize) > 0:
for s in states:
if s in used_states_db:
smt.write("(minimize (|%s| %s))\n" % (smt.modinfo[topmod].minimize.copy().pop(), s))
break
def smt_push():
global asserts_cache_dirty
asserts_cache_dirty = True