gecko/xpcom/analysis/flow.js

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