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Fix the initialized var data flow.

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Now most false positives have been fixed. Just some problems with aliased
vars (next) and then the usual false positives caused by branches.
This commit is contained in:
Bill Currie 2012-11-21 09:42:02 +09:00
parent 547ea78ad7
commit 0dc306c4b7
1 changed files with 31 additions and 17 deletions
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48
tools/qfcc/source/flow.c
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@ -447,6 +447,7 @@ flow_uninitialized (flowgraph_t *graph)
set_t *uninit;
set_t *use;
set_t *def;
set_t *predecessors;
set_iter_t *pred_iter;
set_iter_t *var_iter;
flownode_t *node, *pred;
@ -461,19 +462,21 @@ flow_uninitialized (flowgraph_t *graph)
stdef = set_new ();
tmp = set_new ();
uninit = set_new ();
predecessors = set_new ();
// def for the inital node contains parameters and global vars
def = set_new ();
// in for the inital node contains parameters and global vars
tmp = set_new ();
for (i = 0; i < func->num_vars; i++) {
flowvar_t *var = func->vars[i];
if (flowvar_is_global (var) || flowvar_is_param (var))
set_add (def, i);
set_add (tmp, i);
}
// first, calculate use and def for each block, and initialize the in and
// out sets.
for (i = 0; i < graph->num_nodes; i++) {
node = graph->nodes[i];
use = set_new ();
def = set_new ();
for (st = node->sblock->statements; st; st = st->next) {
flow_analyze_statement (st, stuse, stdef, 0, 0);
live_set_use (stuse, use, def); // init use uses same rules as live
@ -483,26 +486,35 @@ flow_uninitialized (flowgraph_t *graph)
node->init_vars.def = def;
node->init_vars.in = set_new ();
node->init_vars.out = set_new ();
def = set_new ();
}
// flow DOWN the graph in dept-first order
for (i = 0; i < graph->num_nodes; i++) {
node = graph->nodes[0];
set_assign (node->init_vars.in, tmp);
set_assign (node->init_vars.out, tmp);
set_union (node->init_vars.out, node->init_vars.def);
set_assign (tmp, node->init_vars.use);
set_difference (tmp, node->init_vars.in);
set_union (uninit, tmp);
for (i = 1; i < graph->num_nodes; i++) {
node = graph->nodes[graph->dfo[i]];
pred_iter = set_first (node->predecessors);
set_assign (predecessors, node->predecessors);
// not interested in back edges
for (pred_iter = set_first (predecessors); pred_iter;
pred_iter = set_next (pred_iter)) {
pred = graph->nodes[pred_iter->member];
if (pred->dfn >= node->dfn)
set_remove (predecessors, pred->id);
}
set_empty (tmp);
pred_iter = set_first (predecessors);
if (pred_iter) {
do {
// not interested in back edges
pred = graph->nodes[pred_iter->member];
pred_iter = set_next (pred_iter);
} while (pred->dfn >= node->dfn && pred_iter);
if (pred_iter)
set_assign (tmp, pred->init_vars.out);
pred = graph->nodes[pred_iter->member];
set_assign (tmp, pred->init_vars.out);
pred_iter = set_next (pred_iter);
}
for ( ; pred_iter; pred_iter = set_next (pred_iter)) {
if (graph->nodes[pred_iter->member]->dfn >= node->dfn)
continue; // not interested in back edges
set_intersection (tmp,
graph->nodes[pred_iter->member]->init_vars.out);
pred = graph->nodes[pred_iter->member];
set_intersection (tmp, pred->init_vars.out);
}
set_assign (node->init_vars.in, tmp);
set_assign (node->init_vars.out, tmp);
@ -521,11 +533,13 @@ flow_uninitialized (flowgraph_t *graph)
dummy.line = def->line;
dummy.file = def->file;
warning (&dummy, "%s may be used uninitialized", def->name);
puts (operand_string (var->op));
}
set_delete (stuse);
set_delete (stdef);
set_delete (tmp);
set_delete (uninit);
set_delete (predecessors);
}
static void