michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: require({ version: '1.8' });
michael@0: require({ after_gcc_pass: 'cfg' });
michael@0: 
michael@0: include('treehydra.js');
michael@0: 
michael@0: include('util.js');
michael@0: include('gcc_util.js');
michael@0: include('gcc_print.js');
michael@0: include('unstable/adts.js');
michael@0: include('unstable/analysis.js');
michael@0: include('unstable/esp.js');
michael@0: 
michael@0: /* This implements the control flows-through analysis in bug 432917 */
michael@0: var Zero_NonZero = {}
michael@0: include('unstable/zero_nonzero.js', Zero_NonZero);
michael@0: 
michael@0: MapFactory.use_injective = true;
michael@0: 
michael@0: // Print a trace for each function analyzed
michael@0: let TRACE_FUNCTIONS = 0;
michael@0: // Trace operation of the ESP analysis, use 2 or 3 for more detail
michael@0: let TRACE_ESP = 0;
michael@0: // Print time-taken stats
michael@0: let TRACE_PERF = 0;
michael@0: 
michael@0: function process_tree(fndecl) {
michael@0:   // At this point we have a function we want to analyze
michael@0:   if (TRACE_FUNCTIONS) {
michael@0:     print('* function ' + decl_name(fndecl));
michael@0:     print('    ' + loc_string(location_of(fndecl)));
michael@0:   }
michael@0:   if (TRACE_PERF) timer_start(fstring);
michael@0: 
michael@0:   let cfg = function_decl_cfg(fndecl);
michael@0: 
michael@0:   try {
michael@0:     let trace = TRACE_ESP;
michael@0:     let a = new FlowCheck(cfg, trace);
michael@0:     a.run();
michael@0:   } catch (e if e == "skip") {
michael@0:     return
michael@0:   }
michael@0:   print("checked " + decl_name(fndecl))
michael@0:   if (cfg.x_exit_block_ptr.stateIn.substates)
michael@0:     for each (let substate in cfg.x_exit_block_ptr.stateIn.substates.getValues()) {
michael@0:       for each (let v in substate.getVariables()) {
michael@0:         let var_state= substate.get (v)
michael@0:         let blame = substate.getBlame(v)
michael@0:         if (var_state != ESP.TOP && typeof var_state == 'string')
michael@0:           error(decl_name(fndecl) + ": Control did not flow through " +var_state, location_of(blame))
michael@0:       }
michael@0:     }
michael@0:   
michael@0:   if (TRACE_PERF) timer_stop(fstring);
michael@0: }
michael@0: 
michael@0: let track_return_loc = 0;
michael@0: const FLOW_THROUGH = "MUST_FLOW_THROUGH"
michael@0: 
michael@0: function FlowCheck(cfg, trace) {
michael@0:   let found = create_decl_set(); // ones we already found
michael@0:   for (let bb in cfg_bb_iterator(cfg)) {
michael@0:     for (let isn in bb_isn_iterator(bb)) {
michael@0:       switch (isn.tree_code()) {
michael@0:       case GIMPLE_CALL: {
michael@0:         let fn = gimple_call_fndecl(isn)
michael@0:         if (!fn || decl_name(fn) != FLOW_THROUGH)
michael@0:           continue;
michael@0:         this.must_flow_fn = fn
michael@0:         break
michael@0:       }
michael@0:       case GIMPLE_RETURN:
michael@0:         let ret_expr = return_expr(isn);
michael@0:         if (track_return_loc && ret_expr) {
michael@0:           TREE_CHECK(ret_expr, VAR_DECL, RESULT_DECL);
michael@0:           this.rval = ret_expr;
michael@0:         }
michael@0:         break;
michael@0:       }
michael@0:     }
michael@0:   }
michael@0:   if (!this.must_flow_fn)
michael@0:     throw "skip"
michael@0: 
michael@0:   let psvar_list = [new ESP.PropVarSpec(this.must_flow_fn, true)]
michael@0:   
michael@0:   if (this.rval)
michael@0:     psvar_list.push(new ESP.PropVarSpec(this.rval))
michael@0:  
michael@0:   this.zeroNonzero = new Zero_NonZero.Zero_NonZero()
michael@0:   ESP.Analysis.call(this, cfg, psvar_list, Zero_NonZero.meet, trace);
michael@0: }
michael@0: 
michael@0: FlowCheck.prototype = new ESP.Analysis;
michael@0: 
michael@0: function char_star_arg2string(tree) {
michael@0:   return TREE_STRING_POINTER(tree.tree_check(ADDR_EXPR).operands()[0].tree_check(ARRAY_REF).operands()[0])
michael@0: }
michael@0: 
michael@0: // State transition function. Mostly, we delegate everything to
michael@0: // another function as either an assignment or a call.
michael@0: FlowCheck.prototype.flowState = function(isn, state) {
michael@0:   switch (TREE_CODE(isn)) {
michael@0:   case GIMPLE_CALL: {
michael@0:     let fn = gimple_call_fndecl(isn)
michael@0:     if (fn == this.must_flow_fn)
michael@0:       state.assignValue(fn, char_star_arg2string(gimple_call_arg(isn, 0)), isn)
michael@0:     break
michael@0:   }
michael@0:   case GIMPLE_LABEL: {
michael@0:     let label = decl_name(gimple_op(isn, 0))
michael@0:     for ([value, blame] in state.yieldPreconditions(this.must_flow_fn)) {
michael@0:       if (label != value) continue
michael@0:       // reached the goto label we wanted =D
michael@0:       state.assignValue(this.must_flow_fn, ESP.TOP, isn)
michael@0:     }
michael@0:     break
michael@0:   }
michael@0:   case GIMPLE_RETURN:
michael@0:     for ([value, blame] in state.yieldPreconditions(this.must_flow_fn)) {
michael@0:       if (typeof value != 'string') continue
michael@0:       let loc;
michael@0:       if (this.rval)
michael@0:         for ([value, blame] in state.yieldPreconditions(this.rval)) {
michael@0:           loc = value
michael@0:           break
michael@0:         }
michael@0:       error("return without going through label "+ value, loc);
michael@0:       return  
michael@0:     }
michael@0:     break
michael@0:   case GIMPLE_ASSIGN:
michael@0:     if (track_return_loc && gimple_op(isn, 0) == this.rval) {
michael@0:       state.assignValue(this.rval, location_of(isn), isn)
michael@0:       break
michael@0:     }
michael@0:   default:
michael@0:     this.zeroNonzero.flowState(isn, state)
michael@0:   }
michael@0: }
michael@0: 
michael@0: // State transition function to apply branch filters. This is kind
michael@0: // of boilerplate--we're just handling some stuff that GCC generates.
michael@0: FlowCheck.prototype.flowStateCond = function(isn, truth, state) {
michael@0:   this.zeroNonzero.flowStateCond (isn, truth, state)
michael@0: }