Added "sat -prove-skip"

diff --git a/passes/sat/sat.cc b/passes/sat/sat.cc
index fd3d405a7a78f591e48f36b5321c14f9a533815c..c6da4bb42bc9d3685cef2d11bbfa65a13f1a1928 100644 (file)
--- a/passes/sat/sat.cc
+++ b/passes/sat/sat.cc
@@ -917,6 +917,9 @@ struct SatPass : public Pass {
                log("    -prove-asserts\n");
                log("        Prove that all asserts in the design hold.\n");
                log("\n");
+               log("    -prove-skip <N>\n");
+               log("        Do not enforce the prove-condition for the first <N> time steps.\n");
+               log("\n");
                log("    -maxsteps <N>\n");
                log("        Set a maximum length for the induction.\n");
                log("\n");
@@ -945,7 +948,7 @@ struct SatPass : public Pass {
                std::map<int, std::vector<std::pair<std::string, std::string>>> sets_at;
                std::map<int, std::vector<std::string>> unsets_at, sets_def_at, sets_any_undef_at, sets_all_undef_at;
                std::vector<std::string> shows, sets_def, sets_any_undef, sets_all_undef;
-               int loopcount = 0, seq_len = 0, maxsteps = 0, initsteps = 0, timeout = 0;
+               int loopcount = 0, seq_len = 0, maxsteps = 0, initsteps = 0, timeout = 0, prove_skip = 0;
                bool verify = false, fail_on_timeout = false, enable_undef = false, set_def_inputs = false;
                bool ignore_div_by_zero = false, set_init_undef = false, set_init_zero = false, max_undef = false;
                bool tempinduct = false, prove_asserts = false, show_inputs = false, show_outputs = false;
@@ -1059,6 +1062,10 @@ struct SatPass : public Pass {
                                prove_asserts = true;
                                continue;
                        }
+                       if (args[argidx] == "-prove-skip" && argidx+1 < args.size()) {
+                               prove_skip = atoi(args[++argidx].c_str());
+                               continue;
+                       }
                        if (args[argidx] == "-seq" && argidx+1 < args.size()) {
                                seq_len = atoi(args[++argidx].c_str());
                                continue;
@@ -1154,6 +1161,12 @@ struct SatPass : public Pass {
                if (!prove.size() && !prove_x.size() && !prove_asserts && tempinduct)
                        log_cmd_error("Got -tempinduct but nothing to prove!\n");
 
+               if (prove_skip && tempinduct)
+                       log_cmd_error("Options -prove-skip and -tempinduct don't work with each other.\n");
+
+               if (prove_skip >= seq_len && prove_skip > 0)
+                       log_cmd_error("The value of -prove-skip must be smaller than the one of -seq.\n");
+
                if (set_init_undef + set_init_zero + set_init_def > 1)
                        log_cmd_error("The options -set-init-undef, -set-init-def, and -set-init-zero are exclusive!\n");
 
@@ -1359,7 +1372,8 @@ struct SatPass : public Pass {
                                for (int timestep = 1; timestep <= seq_len; timestep++) {
                                        sathelper.setup(timestep);
                                        if (sathelper.prove.size() || sathelper.prove_x.size() || sathelper.prove_asserts)
-                                               prove_bits.push_back(sathelper.setup_proof(timestep));
+                                               if (timestep > prove_skip)
+                                                       prove_bits.push_back(sathelper.setup_proof(timestep));
                                }
                                if (sathelper.prove.size() || sathelper.prove_x.size() || sathelper.prove_asserts)
                                        sathelper.ez.assume(sathelper.ez.NOT(sathelper.ez.expression(ezSAT::OpAnd, prove_bits)));