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authorAlberto Gonzalez <boqwxp@airmail.cc>2020-06-13 08:20:01 +0000
committerAlberto Gonzalez <boqwxp@airmail.cc>2020-07-01 19:51:47 +0000
commit91c20fca724b1f3ec1d0208a9e135b5abd75c0c1 (patch)
tree58d223ad3749d7ed2b8ddcc5c1a2a5c3ca4c9a30 /passes
parentc26a8d1ee051b1bb7925a58d713c452c376c1d25 (diff)
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glift: Add `-simple-cost-model` option
Rather than assigning specific weights to specific versions of taint tracking logic and summing the weights of all GLIFT cells, sum the following values for each GLIFT cell: - 0 if the associated hole/$anyconst cell value is non-zero, i.e. reduced-precision taint tracking logic is chosen at this cell - 1 if the associated hole/$anyconst cell value is zero, i.e. the full-precision taint tracking logic is chosen at this cell This simplified cost modeling reduces the potential for the QBF-SAT solver to minimize taint tracking logic area but significantly simplifies the QBF-SAT problem.
Diffstat (limited to 'passes')
-rw-r--r--passes/cmds/glift.cc65
1 files changed, 45 insertions, 20 deletions
diff --git a/passes/cmds/glift.cc b/passes/cmds/glift.cc
index 42175859f..eee1b2c79 100644
--- a/passes/cmds/glift.cc
+++ b/passes/cmds/glift.cc
@@ -28,7 +28,7 @@ struct GliftPass : public Pass {
private:
bool opt_create_precise_model, opt_create_imprecise_model, opt_create_instrumented_model;
- bool opt_taintconstants, opt_keepoutputs, opt_nocostmodel, opt_instrumentmore;
+ bool opt_taintconstants, opt_keepoutputs, opt_simplecostmodel, opt_nocostmodel, opt_instrumentmore;
std::vector<std::string> args;
std::vector<std::string>::size_type argidx;
std::vector<RTLIL::Wire *> new_taint_outputs;
@@ -59,6 +59,10 @@ struct GliftPass : public Pass {
opt_keepoutputs = true;
continue;
}
+ if (args[argidx] == "-simple-cost-model") {
+ opt_simplecostmodel = true;
+ continue;
+ }
if (args[argidx] == "-no-cost-model") {
opt_nocostmodel = true;
continue;
@@ -73,6 +77,10 @@ struct GliftPass : public Pass {
log_cmd_error("No command provided. See help for usage.\n");
if(static_cast<int>(opt_create_precise_model) + static_cast<int>(opt_create_imprecise_model) + static_cast<int>(opt_create_instrumented_model) != 1)
log_cmd_error("Only one command may be specified. See help for usage.\n");
+ if(opt_simplecostmodel && opt_nocostmodel)
+ log_cmd_error("Only one of `-simple-cost-model` and `-no-cost-model` may be specified. See help for usage.\n");
+ if((opt_simplecostmodel || opt_nocostmodel) && !opt_create_instrumented_model)
+ log_cmd_error("Options `-simple-cost-model` and `-no-cost-model` may only be used with `-create-instrumented-model`. See help for usage.\n");
}
RTLIL::SigSpec get_corresponding_taint_signal(RTLIL::SigSpec sig) {
@@ -153,25 +161,33 @@ struct GliftPass : public Pass {
RTLIL::SigSpec score_metamux_select(const RTLIL::SigSpec &metamux_select) {
log_assert(metamux_select.is_wire());
- auto num_versions = opt_instrumentmore? 8 : 4;
- auto select_width = log2(num_versions);
- log_assert(metamux_select.as_wire()->width == select_width);
-
- std::vector<RTLIL::Const> costs = {5, 2, 2, 1, 0, 0, 0, 0}; //in terms of AND/OR gates
-
- std::vector<RTLIL::SigSpec> next_pmux_y_ports, pmux_y_ports(costs.begin(), costs.begin() + num_versions);
- for (auto i = 0; pmux_y_ports.size() > 1; ++i) {
- for (auto j = 0; j+1 < GetSize(pmux_y_ports); j += 2) {
- next_pmux_y_ports.emplace_back(module->Pmux(stringf("%s_mux_%d_%d", metamux_select.as_wire()->name.c_str(), i, j), pmux_y_ports[j], pmux_y_ports[j+1], metamux_select[GetSize(metamux_select) - 1 - i], metamux_select.as_wire()->get_src_attribute()));
+ if (opt_simplecostmodel) {
+ //The complex model is an area model, so a lower score should mean smaller.
+ //In this case, a nonzero hole metamux select value means less logic.
+ //Thus we should invert the ReduceOr over the metamux_select signal.
+ RTLIL::SigSpec pmux_select = module->ReduceOr(metamux_select.as_wire()->name.str() + "_nonzero", metamux_select);
+ return module->Pmux(NEW_ID, RTLIL::Const(1), RTLIL::Const(0), pmux_select, metamux_select.as_wire()->get_src_attribute());
+ } else {
+ auto num_versions = opt_instrumentmore? 8 : 4;
+ auto select_width = log2(num_versions);
+ log_assert(metamux_select.as_wire()->width == select_width);
+
+ std::vector<RTLIL::Const> costs = {5, 2, 2, 1, 0, 0, 0, 0}; //in terms of AND/OR gates
+
+ std::vector<RTLIL::SigSpec> next_pmux_y_ports, pmux_y_ports(costs.begin(), costs.begin() + num_versions);
+ for (auto i = 0; pmux_y_ports.size() > 1; ++i) {
+ for (auto j = 0; j+1 < GetSize(pmux_y_ports); j += 2) {
+ next_pmux_y_ports.emplace_back(module->Pmux(stringf("%s_mux_%d_%d", metamux_select.as_wire()->name.c_str(), i, j), pmux_y_ports[j], pmux_y_ports[j+1], metamux_select[GetSize(metamux_select) - 1 - i], metamux_select.as_wire()->get_src_attribute()));
+ }
+ if (GetSize(pmux_y_ports) % 2 == 1)
+ next_pmux_y_ports.push_back(pmux_y_ports[GetSize(pmux_y_ports) - 1]);
+ pmux_y_ports.swap(next_pmux_y_ports);
+ next_pmux_y_ports.clear();
}
- if (GetSize(pmux_y_ports) % 2 == 1)
- next_pmux_y_ports.push_back(pmux_y_ports[GetSize(pmux_y_ports) - 1]);
- pmux_y_ports.swap(next_pmux_y_ports);
- next_pmux_y_ports.clear();
- }
- log_assert(pmux_y_ports.size() == 1);
- return pmux_y_ports[0];
+ log_assert(pmux_y_ports.size() == 1);
+ return pmux_y_ports[0];
+ }
}
void create_glift_logic() {
@@ -276,7 +292,7 @@ struct GliftPass : public Pass {
new_taint_outputs.push_back(first.as_wire());
} //end foreach conn in connections
- //Create a rough model of area by summing the "weight" score of each meta-mux select:
+ //Create a rough model of area by summing the (potentially simplified) "weight" score of each meta-mux select:
if (!opt_nocostmodel) {
std::vector<RTLIL::SigSpec> meta_mux_select_sums;
std::vector<RTLIL::SigSpec> meta_mux_select_sums_buf;
@@ -317,6 +333,7 @@ struct GliftPass : public Pass {
opt_create_instrumented_model = false;
opt_taintconstants = false;
opt_keepoutputs = false;
+ opt_simplecostmodel = false;
opt_nocostmodel = false;
opt_instrumentmore = false;
module = nullptr;
@@ -328,7 +345,7 @@ struct GliftPass : public Pass {
public:
- GliftPass() : Pass("glift", "create GLIFT models and optimization problems"), opt_create_precise_model(false), opt_create_imprecise_model(false), opt_create_instrumented_model(false), opt_taintconstants(false), opt_keepoutputs(false), opt_nocostmodel(false), opt_instrumentmore(false), module(nullptr) { }
+ GliftPass() : Pass("glift", "create GLIFT models and optimization problems"), opt_create_precise_model(false), opt_create_imprecise_model(false), opt_create_instrumented_model(false), opt_taintconstants(false), opt_keepoutputs(false), opt_simplecostmodel(false), opt_nocostmodel(false), opt_instrumentmore(false), module(nullptr) { }
void help() YS_OVERRIDE
{
@@ -388,6 +405,14 @@ struct GliftPass : public Pass {
log(" alongside the orignal outputs.\n");
log(" (default: original module outputs are removed)\n");
log("\n");
+ log(" -simple-cost-model\n");
+ log(" Do not model logic area. Instead model the number of non-zero assignments to $anyconsts.\n");
+ log(" Taint tracking logic versions vary in their size, but all reduced-precision versions are\n");
+ log(" significantly smaller than the fully-precise version. A non-zero $anyconst assignment means\n");
+ log(" that reduced-precision taint tracking logic was chosen for some gate.\n");
+ log(" Only applicable in combination with `-create-instrumented-model`.\n");
+ log(" (default: use a complex model and give that wire the \"keep\" and \"minimize\" attributes)\n");
+ log("\n");
log(" -no-cost-model\n");
log(" Do not model taint tracking logic area and do not create a `__glift_weight` wire.\n");
log(" Only applicable in combination with `-create-instrumented-model`.\n");