X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=execution.cc;h=2a7e0dadd1e0918ac21b5f43dd4e3608935b8f18;hb=refs%2Fheads%2Fmaster;hp=07866fe804a308054c716ae4eb92ba146cd53e15;hpb=fb6d374952284313141eaee75ecd322209d152db;p=model-checker.git diff --git a/execution.cc b/execution.cc index 07866fe..2a7e0da 100644 --- a/execution.cc +++ b/execution.cc @@ -30,9 +30,11 @@ struct model_snapshot_members { next_backtrack(NULL), bugs(), failed_promise(false), + hard_failed_promise(false), too_many_reads(false), no_valid_reads(false), bad_synchronization(false), + bad_sc_read(false), asserted(false) { } @@ -47,10 +49,12 @@ struct model_snapshot_members { ModelAction *next_backtrack; SnapVector bugs; bool failed_promise; + bool hard_failed_promise; bool too_many_reads; bool no_valid_reads; /** @brief Incorrectly-ordered synchronization was made */ bool bad_synchronization; + bool bad_sc_read; bool asserted; SNAPSHOTALLOC @@ -200,6 +204,13 @@ void ModelExecution::set_bad_synchronization() priv->bad_synchronization = true; } +/** @brief Alert the model-checker that an incorrectly-ordered + * synchronization was made */ +void ModelExecution::set_bad_sc_read() +{ + priv->bad_sc_read = true; +} + bool ModelExecution::assert_bug(const char *msg) { priv->bugs.push_back(new bug_message(msg)); @@ -755,12 +766,13 @@ bool ModelExecution::process_mutex(ModelAction *curr) /** * @brief Check if the current pending promises allow a future value to be sent * - * If one of the following is true: - * (a) there are no pending promises - * (b) the reader and writer do not cross any promises - * Then, it is safe to pass a future value back now. + * It is unsafe to pass a future value back if there exists a pending promise Pr + * such that: + * + * reader --exec-> Pr --exec-> writer * - * Otherwise, we must save the pending future value until (a) or (b) is true + * If such Pr exists, we must save the pending future value until Pr is + * resolved. * * @param writer The operation which sends the future value. Must be a write. * @param reader The operation which will observe the value. Must be a read. @@ -769,8 +781,6 @@ bool ModelExecution::process_mutex(ModelAction *curr) bool ModelExecution::promises_may_allow(const ModelAction *writer, const ModelAction *reader) const { - if (promises.empty()) - return true; for (int i = promises.size() - 1; i >= 0; i--) { ModelAction *pr = promises[i]->get_reader(0); //reader is after promise...doesn't cross any promise @@ -1305,6 +1315,12 @@ ModelAction * ModelExecution::check_current_action(ModelAction *curr) if (rf) { if (r_modification_order(act, rf)) updated = true; + if (act->is_seqcst()) { + ModelAction *last_sc_write = get_last_seq_cst_write(act); + if (last_sc_write != NULL && rf->happens_before(last_sc_write)) { + set_bad_sc_read(); + } + } } else if (promise) { if (r_modification_order(act, promise)) updated = true; @@ -1376,7 +1392,7 @@ void ModelExecution::print_infeasibility(const char *prefix) const char *ptr = buf; if (mo_graph->checkForCycles()) ptr += sprintf(ptr, "[mo cycle]"); - if (priv->failed_promise) + if (priv->failed_promise || priv->hard_failed_promise) ptr += sprintf(ptr, "[failed promise]"); if (priv->too_many_reads) ptr += sprintf(ptr, "[too many reads]"); @@ -1384,6 +1400,8 @@ void ModelExecution::print_infeasibility(const char *prefix) const ptr += sprintf(ptr, "[no valid reads-from]"); if (priv->bad_synchronization) ptr += sprintf(ptr, "[bad sw ordering]"); + if (priv->bad_sc_read) + ptr += sprintf(ptr, "[bad sc read]"); if (promises_expired()) ptr += sprintf(ptr, "[promise expired]"); if (promises.size() != 0) @@ -1398,7 +1416,8 @@ void ModelExecution::print_infeasibility(const char *prefix) const */ bool ModelExecution::is_feasible_prefix_ignore_relseq() const { - return !is_infeasible() && promises.size() == 0; + return !is_infeasible() && promises.size() == 0 && ! priv->failed_promise; + } /** @@ -1411,9 +1430,10 @@ bool ModelExecution::is_infeasible() const { return mo_graph->checkForCycles() || priv->no_valid_reads || - priv->failed_promise || priv->too_many_reads || priv->bad_synchronization || + priv->bad_sc_read || + priv->hard_failed_promise || promises_expired(); } @@ -1614,12 +1634,6 @@ bool ModelExecution::r_modification_order(ModelAction *curr, const rf_type *rf) } } - /* C++, Section 29.3 statement 3 (second subpoint) */ - if (curr->is_seqcst() && last_sc_write && act == last_sc_write) { - added = mo_graph->addEdge(act, rf) || added; - break; - } - /* * Include at most one act per-thread that "happens * before" curr @@ -1751,9 +1765,10 @@ bool ModelExecution::w_modification_order(ModelAction *curr, ModelVectoraddEdge(act, curr) || added; else if (act->is_read()) { //if previous read accessed a null, just keep going - if (act->get_reads_from() == NULL) - continue; - added = mo_graph->addEdge(act->get_reads_from(), curr) || added; + if (act->get_reads_from() == NULL) { + added = mo_graph->addEdge(act->get_reads_from_promise(), curr) || added; + } else + added = mo_graph->addEdge(act->get_reads_from(), curr) || added; } break; } else if (act->is_read() && !act->could_synchronize_with(curr) && @@ -1770,7 +1785,8 @@ bool ModelExecution::w_modification_order(ModelAction *curr, ModelVectorpush_back(act); else if (curr->is_rmw() && act->is_rmw() && curr->get_reads_from() && curr->get_reads_from() == act->get_reads_from()) @@ -1792,6 +1808,50 @@ bool ModelExecution::w_modification_order(ModelAction *curr, ModelVectorget_tid(); + for(unsigned int i = promises.size(); i>0; i--) { + Promise *pr=promises[i-1]; + if (!pr->same_location(write)) + continue; + //the reading thread is the only thread that can resolve the promise + if (pr->get_num_was_available_threads()==1 && pr->thread_was_available(read->get_tid())) { + for(unsigned int j=0;jget_num_readers();j++) { + ModelAction *prreader=pr->get_reader(j); + //the writing thread reads from the promise before the write + if (prreader->get_tid()==write_tid && + (*prreader)<(*write)) { + if ((*read)>(*prreader)) { + //check that we don't have a read between the read and promise + //from the same thread as read + bool okay=false; + for(const ModelAction *tmp=read;tmp!=prreader;) { + tmp=tmp->get_node()->get_parent()->get_action(); + if (tmp->is_read() && tmp->same_thread(read)) { + okay=true; + break; + } + } + if (okay) + continue; + } + return false; + } + } + } + } + return true; +} + + /** Arbitrary reads from the future are not allowed. Section 29.3 * part 9 places some constraints. This method checks one result of constraint * constraint. Others require compiler support. */ @@ -1820,6 +1880,7 @@ bool ModelExecution::thin_air_constraint_may_allow(const ModelAction *writer, co * require compiler support): * * If X --hb-> Y --mo-> Z, then X should not read from Z. + * If X --hb-> Y, A --rf-> Y, and A --mo-> Z, then X should not read from Z. */ bool ModelExecution::mo_may_allow(const ModelAction *writer, const ModelAction *reader) { @@ -2353,7 +2414,7 @@ bool ModelExecution::resolve_promise(ModelAction *write, Promise *promise, /* Make sure the promise's value matches the write's value */ ASSERT(promise->is_compatible(write) && promise->same_value(write)); if (!mo_graph->resolvePromise(promise, write)) - priv->failed_promise = true; + priv->hard_failed_promise = true; /** * @todo It is possible to end up in an inconsistent state, where a @@ -2465,7 +2526,7 @@ void ModelExecution::mo_check_promises(const ModelAction *act, bool is_read_chec if (!pread->happens_before(act)) continue; if (mo_graph->checkPromise(write, promise)) { - priv->failed_promise = true; + priv->hard_failed_promise = true; return; } break; @@ -2477,7 +2538,7 @@ void ModelExecution::mo_check_promises(const ModelAction *act, bool is_read_chec if (mo_graph->checkReachable(promise, write)) { if (mo_graph->checkPromise(write, promise)) { - priv->failed_promise = true; + priv->hard_failed_promise = true; return; } }