adding t-smt

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/smt/smt_parallel.h

@@ -0,0 +1,41 @@
+/*++
+Copyright (c) 2020 Microsoft Corporation
+
+Module Name:
+
+    smt_parallel.h
+
+Abstract:
+
+    Parallel SMT, portfolio loop specialized to SMT core.
+
+Author:
+
+    nbjorner 2020-01-31
+
+Revision History:
+
+--*/
+#pragma once
+
+#include "smt/smt_context.h"
+
+namespace smt {
+
+    class parallel {
+        context& ctx;
+        expr_ref_vector     m_unit_trail;
+        obj_hashtable<expr> m_unit_set;
+        unsigned_vector     m_unit_lim;
+        std::mutex          m_mux;
+    public:
+        parallel(context& ctx): ctx(ctx), m_unit_trail(ctx.m) {}
+
+        lbool operator()(expr_ref_vector const& asms);
+
+        void add_unit(context& ctx, expr* e);
+
+        void get_units(unsigned idx, context& pctx);
+    };
+
+}