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Implement depth-first searching for flow graphs.

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This fixes the bogusly irreducible graphs.
This commit is contained in:
Bill Currie 2012-11-01 15:31:35 +09:00
parent 53622dbb99
commit 8c5a2b3d11
2 changed files with 35 additions and 4 deletions
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1
tools/qfcc/include/flow.h
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@ -64,6 +64,7 @@ typedef struct flownode_s {
unsigned *successors; //< indices into siblings
unsigned num_nodes; //< number of nodes or sblocks
unsigned region; //< the region of which this node is a member
unsigned *depth_first; //< indices into siblings in depth-first order
/// \name Node pointers.
/// Only one of \a sblocks or \a nodes will be non-null. If \a sblocks is
/// non-null, then this is an innermost flow-node, otherwise \a nodes

38
tools/qfcc/source/flow.c
View file

@ -362,6 +362,32 @@ flow_find_loops (flownode_t **node_list, unsigned num_nodes)
return loop_list;
}
static void
df_search (flownode_t *graph, set_t *visited, unsigned *i, unsigned n)
{
int j;
flownode_t *node;
set_add (visited, n);
node = graph->siblings[n];
for (j = 0; j < node->num_succ; j++) {
if (!set_is_member (visited, node->successors[j])) {
df_search (graph, visited, i, node->successors[j]);
}
}
graph->depth_first[--*i] = n;
}
static void
flow_depth_first (flownode_t *graph)
{
unsigned i = graph->num_siblings;
set_t *visited = set_new ();
graph->depth_first = malloc (graph->num_siblings * sizeof (unsigned));
df_search (graph, visited, &i, 0);
}
static int
is_predecessor (unsigned m, set_t *I, flownode_t *graph)
{
@ -415,10 +441,11 @@ flow_reduce (flownode_t *graph)
// than nodes in graph.
I = malloc (graph->num_siblings * sizeof (set_t *));
I[count++] = select_nodes (graph, G, 0);
for (m = set_first (G); m; m = set_first (G)) {
I[count++] = select_nodes (graph, G, m->member);
set_delstate (m);
for (i = 0; i < graph->num_siblings; i++) {
unsigned m = graph->depth_first[i];
if (!set_is_member (G, m))
continue;
I[count++] = select_nodes (graph, G, m);
}
if (count == graph->num_siblings)
@ -458,6 +485,7 @@ flow_reduce (flownode_t *graph)
node->successors[j] = m->member;
}
flow_find_predecessors (node_list, count);
flow_depth_first (node_list[0]);
irreducible:
for (i = 0; i < count; i++)
set_delete (I[i]);
@ -530,6 +558,8 @@ flow_build_graph (function_t *func)
}
}
flow_find_predecessors (node_list, num_blocks);
flow_depth_first (node_list[0]);
flow_calc_dominators (node_list, num_blocks);
func->loops = flow_find_loops (node_list, num_blocks);
func->flow = node_list[0];