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ed42557dd1
When a global variable is accessed via only an alias in a function the actual def's flowvar would remain in the state it was from the last function that accessed the global normally. This would result in invalid flowvar accesses which can be difficult to reproduce (thus no test case).
1641 lines
44 KiB
C
1641 lines
44 KiB
C
/*
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flow.c
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Flow graph analysis
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Copyright (C) 2012 Bill Currie <bill@taniwha.org>
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Author: Bill Currie <bill@taniwha.org>
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Date: 2012/10/30
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to:
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Free Software Foundation, Inc.
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59 Temple Place - Suite 330
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Boston, MA 02111-1307, USA
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#ifdef HAVE_STRING_H
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# include <string.h>
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#endif
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#ifdef HAVE_STRINGS_H
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# include <strings.h>
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#endif
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#include <stdlib.h>
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#include "QF/alloc.h"
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#include "QF/dstring.h"
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#include "QF/set.h"
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#include "QF/va.h"
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#include "tools/qfcc/include/dags.h"
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#include "tools/qfcc/include/def.h"
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#include "tools/qfcc/include/defspace.h"
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#include "tools/qfcc/include/diagnostic.h"
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#include "tools/qfcc/include/dot.h"
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#include "tools/qfcc/include/flow.h"
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#include "tools/qfcc/include/function.h"
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#include "tools/qfcc/include/options.h"
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#include "tools/qfcc/include/qfcc.h"
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#include "tools/qfcc/include/statements.h"
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#include "tools/qfcc/include/symtab.h"
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#include "tools/qfcc/include/type.h"
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/// \addtogroup qfcc_flow
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///@{
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/** Static operand definitions for the ever present return and parameter slots.
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*/
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static struct {
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const char *name;
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operand_t op;
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} flow_params[] = {
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{".return", {0, op_def}},
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{".param_0", {0, op_def}},
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{".param_1", {0, op_def}},
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{".param_2", {0, op_def}},
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{".param_3", {0, op_def}},
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{".param_4", {0, op_def}},
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{".param_5", {0, op_def}},
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{".param_6", {0, op_def}},
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{".param_7", {0, op_def}},
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};
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static const int num_flow_params = sizeof(flow_params)/sizeof(flow_params[0]);
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/** \name Flow analysis memory management */
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///@{
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static flowvar_t *vars_freelist; ///< flowvar pool
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static flowloop_t *loops_freelist; ///< flow loop pool
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static flownode_t *nodes_freelist; ///< flow node pool
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static flowgraph_t *graphs_freelist; ///< flow graph pool
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/** Allocate a new flow var.
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*
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* The var's use and define sets are initialized to empty.
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*/
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static flowvar_t *
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new_flowvar (void)
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{
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flowvar_t *var;
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ALLOC (256, flowvar_t, vars, var);
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var->use = set_new ();
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var->define = set_new ();
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return var;
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}
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/** Delete a flow var
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*/
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static void
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delete_flowvar (flowvar_t *var)
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{
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set_delete (var->use);
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set_delete (var->define);
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FREE (vars, var);
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}
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/** Allocate a new flow loop.
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*
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* The loop's nodes set is initialized to the empty set.
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*/
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static flowloop_t *
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new_loop (void)
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{
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flowloop_t *loop;
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ALLOC (256, flowloop_t, loops, loop);
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loop->nodes = set_new ();
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return loop;
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}
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/** Free a flow loop and its nodes set.
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*/
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static void
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delete_loop (flowloop_t *loop)
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{
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set_delete (loop->nodes);
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FREE (loops, loop);
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}
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/** Allocate a new flow node.
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*
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* The node is completely empty.
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*/
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static flownode_t *
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new_node (void)
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{
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flownode_t *node;
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ALLOC (256, flownode_t, nodes, node);
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return node;
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}
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/** Free a flow node and its resources.
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*
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* \bug not global_vars or the vars and defs sets?
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*/
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static void
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delete_node (flownode_t *node)
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{
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if (node->predecessors)
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set_delete (node->predecessors);
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if (node->successors)
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set_delete (node->successors);
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if (node->edges)
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set_delete (node->edges);
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if (node->dom)
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set_delete (node->dom);
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FREE (nodes, node);
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}
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/** Allocate a new flow graph.
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*
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* The graph is completely empty.
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*/
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static flowgraph_t *
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new_graph (void)
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{
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flowgraph_t *graph;
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ALLOC (256, flowgraph_t, graphs, graph);
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return graph;
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}
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/** Return a flow graph and its resources to the pools.
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*
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* \bug except loops?
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*/
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static void __attribute__((unused))
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delete_graph (flowgraph_t *graph)
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{
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int i;
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if (graph->nodes) {
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for (i = 0; i < graph->num_nodes; i++)
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delete_node (graph->nodes[i]);
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free (graph->nodes);
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}
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if (graph->edges)
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free (graph->edges);
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if (graph->dfst)
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set_delete (graph->dfst);
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if (graph->depth_first)
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free (graph->depth_first);
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FREE (graphs, graph);
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}
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///@}
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/** \name Flowvar classification */
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///@{
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/** Check if the flowvar refers to a global variable.
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*
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* For the flowvar to refer to a global variable, the flowvar's operand
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* must be a def operand (but the def itself may be an alias of the real def)
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* and the rel def must not have its def_t::local flag set. This means that
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* function-scope static variables are not considered local (ie, only
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* non-static function-scope variables and function parameters are considered
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* local (temp vars are local too, but are not represented by \a op_def)).
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*/
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static int
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flowvar_is_global (flowvar_t *var)
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{
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def_t *def;
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if (var->op->op_type != op_def)
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return 0;
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def = var->op->o.def;
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if (def->alias)
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def = def->alias;
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if (def->local)
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return 0;
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return 1;
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}
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/** Check if the flowvar refers to a function parameter.
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*
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* For the flowvar to refer to a function parameter, the flowvar's operand
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* must be a def operand (but the def itself may be an alias of the real def)
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* and the rel def must have both its def_t::local and def_t::param flags set.
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*
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* Temp vars are are not represented by op_def, so no mistake can be made.
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*/
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static int
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flowvar_is_param (flowvar_t *var)
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{
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def_t *def;
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if (var->op->op_type != op_def)
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return 0;
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def = var->op->o.def;
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if (def->alias)
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def = def->alias;
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if (!def->local)
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return 0;
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if (!def->param)
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return 0;
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return 1;
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}
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/** Check if the flowvar refers to a function parameter.
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*
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* As this is simply "neither global nor pamam", all other flowvars are
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* considered local, in particular actual non-staic function scope variables
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* and temp vars.
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*/
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static int
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flowvar_is_local (flowvar_t *var)
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{
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return !(flowvar_is_global (var) || flowvar_is_param (var));
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}
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///@}
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/** Extract the def from a def or temp flowvar.
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*
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* It is an error for the operand referenced by the flowvar to be anything
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* other than a real def or temp.
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*/
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static __attribute__((pure)) def_t *
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flowvar_get_def (flowvar_t *var)
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{
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operand_t *op = var->op;
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switch (op->op_type) {
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case op_def:
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return op->o.def;
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case op_value:
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case op_label:
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return 0;
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case op_temp:
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return op->o.tempop.def;
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case op_alias:
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internal_error (op->expr, "unexpected alias operand");
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case op_nil:
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internal_error (op->expr, "unexpected nil operand");
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}
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internal_error (op->expr, "oops, blue pill");
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return 0;
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}
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/** Get a def or temp var operand's flowvar.
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*
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* Other operand types never have a flowvar.
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*
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* If the operand does not yet have a flowvar, one is created and assigned
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* to the operand.
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*/
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flowvar_t *
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flow_get_var (operand_t *op)
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{
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if (!op)
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return 0;
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if (op->op_type == op_temp) {
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if (!op->o.tempop.flowvar)
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op->o.tempop.flowvar = new_flowvar ();
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return op->o.tempop.flowvar;
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}
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if (op->op_type == op_def) {
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if (!op->o.def->flowvar)
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op->o.def->flowvar = new_flowvar ();
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return op->o.def->flowvar;
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}
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return 0;
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}
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/** Indicate whether the operand should be counted.
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*
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* If the operand is a def or temp var operand, and it has not already been
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* counted, then it is counted, otherwise it is not.
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* \return 1 if the operand should be counted, 0 if not
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*/
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static int
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count_operand (operand_t *op)
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{
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flowvar_t *var;
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if (!op)
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return 0;
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if (op->op_type == op_label)
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return 0;
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var = flow_get_var (op);
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/** Flowvars are initialized with number == 0, and any global flowvar
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* used by a function will always have a number >= 0 after flow analysis,
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* and local flowvars will always be 0 before flow analysis, so use -1
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* to indicate the variable has been counted.
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*
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* Also, since this is the beginning of flow analysis for this function,
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* ensure the define/use sets for global vars are empty. However, since
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* checking if a var is global is too much trouble, just clear them all.
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*/
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if (var && var->number != -1) {
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set_empty (var->use);
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set_empty (var->define);
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var->number = -1;
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return 1;
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}
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return 0;
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}
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/** Allocate flow analysis pseudo address space to a temporary variable.
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*
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* If the operand already has an address allocated (flowvar_t::flowaddr is
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* not 0), then the already allocated address is returned.
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*
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* If the operand refers to an alias, the alias chain is followed to the
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* actual temp var operand and the real temp var is allocated space if it
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* has not allready been alloced.
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*
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* The operand is given the address of the real temp var operand plus whatever
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* offset the operand has.
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*
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* Real temp var operands must have a zero offset.
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*
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* The operand address is set in \a op and returned.
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*/
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static int
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get_temp_address (function_t *func, operand_t *op)
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{
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operand_t *top = op;
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if (op->o.tempop.flowaddr) {
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return op->o.tempop.flowaddr;
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}
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while (top->o.tempop.alias) {
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top = top->o.tempop.alias;
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}
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if (!top->o.tempop.flowaddr) {
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top->o.tempop.flowaddr = func->tmpaddr;
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func->tmpaddr += top->size;
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}
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if (top->o.tempop.offset) {
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internal_error (top->expr, "real tempop with a non-zero offset");
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}
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op->o.tempop.flowaddr = top->o.tempop.flowaddr + op->o.tempop.offset;
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return op->o.tempop.flowaddr;
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}
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/** Add an operand's flowvar to the function's list of variables.
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*/
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static void
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add_operand (function_t *func, operand_t *op)
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{
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flowvar_t *var;
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if (!op)
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return;
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if (op->op_type == op_label)
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return;
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var = flow_get_var (op);
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/** If the flowvar number is still -1, then the flowvar has not yet been
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* added to the list of variables referenced by the function.
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*
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* The flowvar's flowvar_t::number is set to its index in the function's
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* list of flowvars.
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*
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* Also, temp and local flowvars are assigned addresses from the flow
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* analysys pseudo address space so partial accesses can be analyzed.
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*/
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if (var && var->number == -1) {
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var->number = func->num_vars++;
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var->op = op;
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func->vars[var->number] = var;
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if (op->op_type == op_temp) {
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var->flowaddr = get_temp_address (func, op);
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} else if (flowvar_is_local (var)) {
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var->flowaddr = func->num_statements + def_offset (var->op->o.def);
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}
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}
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}
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/** Create symbols and defs for params/return if not already available.
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*/
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static symbol_t *
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param_symbol (const char *name)
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{
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symbol_t *sym;
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sym = make_symbol (name, &type_param, pr.symtab->space, sc_extern);
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if (!sym->table)
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symtab_addsymbol (pr.symtab, sym);
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return sym;
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}
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/** Build an array of all the statements in a function.
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The array exists so statements can be referenced by number and thus used
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in sets.
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The statement references in the array (function_t::statements) are in the
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same order as they are within the statement blocks (function_t::sblock)
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and with the blocks in the same order as the linked list of blocks.
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*/
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static void
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flow_build_statements (function_t *func)
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{
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sblock_t *sblock;
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statement_t *s;
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int num_statements = 0;
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for (sblock = func->sblock; sblock; sblock = sblock->next) {
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for (s = sblock->statements; s; s = s->next)
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s->number = num_statements++;
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}
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if (!num_statements)
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return;
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func->statements = malloc (num_statements * sizeof (statement_t *));
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func->num_statements = num_statements;
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for (sblock = func->sblock; sblock; sblock = sblock->next) {
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for (s = sblock->statements; s; s = s->next)
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func->statements[s->number] = s;
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}
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}
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static int flow_def_clear_flowvars (def_t *def, void *data)
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{
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if (def->flowvar) {
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delete_flowvar (def->flowvar);
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}
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def->flowvar = 0;
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return 0;
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}
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/** Build an array of all the variables used by a function
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*
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* The array exists so variables can be referenced by number and thus used
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* in sets. However, because larger variables may be aliased by smaller types,
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* their representation is more complicated.
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*
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* # Local variable representation
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* Defined local vars add their address in local space to the number of
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* statements in the function. Thus their flow analysis address in in the
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* range:
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*
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* ([num_statements ... num_statements+localsize])
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*
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* with a set element in flowvar_t::define for each word used by the var.
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* That is, single word types (int, float, pointer, etc) have one element,
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* doubles have two adjacant elements, and vectors and quaternions have
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* three and four elements respectively (also adjacant). Structural types
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* (struct, union, array) have as many adjacant elements as their size
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* dictates.
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*
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* Temporary vars are pseudo allocated and their addresses are added as
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* for normal local vars.
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*
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* Note, however, that flowvar_t::define also includes real function
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* statements that assign to the variable.
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*
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* # Pseudo Address Space
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* Temporary variables are _effectively_ local variables and thus will
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* be treated as such by the analizer in that their addresses and sizes
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* will be used to determine which and how many set elements to use.
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*
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* However, at this stage, temporary variables do not have any address
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* space assigned to them because their lifetimes are generally limited
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* to a few statements and the memory used for the temp vars may be
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* recycled. Thus, give temp vars a pseudo address space just past the
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* address space used for source-defined local variables. As each temp
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* var is added to the analyzer, get_temp_address() assigns the temp var
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* an address using function_t::tmpaddr as a starting point.
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*
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* add_operand() takes care of setting flowvar_t::flowaddr for both locals
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* and temps.
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*/
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static void
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flow_build_vars (function_t *func)
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{
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statement_t *s;
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operand_t *operands[FLOW_OPERANDS];
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int num_vars = 0;
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int i, j;
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set_t *stuse;
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set_t *stdef;
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set_iter_t *var_i;
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flowvar_t *var;
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|
|
// First, run through the statements making sure any accessed variables
|
|
// have their flowvars reset. Local variables will be fine, but global
|
|
// variables make have had flowvars added in a previous function, and it's
|
|
// easier to just clear them all.
|
|
// This is done before .return and .param so they won't get reset just
|
|
// after being counted
|
|
for (i = 0; i < func->num_statements; i++) {
|
|
s = func->statements[i];
|
|
flow_analyze_statement (s, 0, 0, 0, operands);
|
|
for (j = 0; j < FLOW_OPERANDS; j++) {
|
|
if (operands[j] && operands[j]->op_type == op_def) {
|
|
def_visit_all (operands[j]->o.def, 0,
|
|
flow_def_clear_flowvars, 0);
|
|
}
|
|
}
|
|
}
|
|
// count .return and .param_[0-7] as they are always needed
|
|
for (i = 0; i < num_flow_params; i++) {
|
|
def_t *def = param_symbol (flow_params[i].name)->s.def;
|
|
def_visit_all (def, 0, flow_def_clear_flowvars, 0);
|
|
flow_params[i].op.o.def = def;
|
|
num_vars += count_operand (&flow_params[i].op);
|
|
}
|
|
// then run through the statements in the function looking for accessed
|
|
// variables
|
|
for (i = 0; i < func->num_statements; i++) {
|
|
s = func->statements[i];
|
|
flow_analyze_statement (s, 0, 0, 0, operands);
|
|
for (j = 0; j < 4; j++)
|
|
num_vars += count_operand (operands[j]);
|
|
}
|
|
if (!num_vars)
|
|
return;
|
|
|
|
func->vars = malloc (num_vars * sizeof (flowvar_t *));
|
|
|
|
stuse = set_new ();
|
|
stdef = set_new ();
|
|
|
|
// set up pseudo address space for temp vars so accessing tmp vars
|
|
// though aliases analyses correctly
|
|
func->tmpaddr = func->num_statements + func->symtab->space->size;
|
|
|
|
func->num_vars = 0; // incremented by add_operand
|
|
// first, add .return and .param_[0-7] as they are always needed
|
|
for (i = 0; i < num_flow_params; i++)
|
|
add_operand (func, &flow_params[i].op);
|
|
// then run through the statements in the function adding accessed
|
|
// variables
|
|
for (i = 0; i < func->num_statements; i++) {
|
|
s = func->statements[i];
|
|
flow_analyze_statement (s, 0, 0, 0, operands);
|
|
for (j = 0; j < 4; j++)
|
|
add_operand (func, operands[j]);
|
|
}
|
|
// and set the use/def sets for the vars (has to be a separate pass
|
|
// because the allias handling reqruires the flow address to be valid
|
|
// (ie, not -1)
|
|
for (i = 0; i < func->num_statements; i++) {
|
|
s = func->statements[i];
|
|
flow_analyze_statement (s, stuse, stdef, 0, 0);
|
|
for (var_i = set_first (stdef); var_i; var_i = set_next (var_i)) {
|
|
var = func->vars[var_i->element];
|
|
set_add (var->define, i);
|
|
}
|
|
for (var_i = set_first (stuse); var_i; var_i = set_next (var_i)) {
|
|
var = func->vars[var_i->element];
|
|
set_add (var->use, i);
|
|
}
|
|
}
|
|
func->global_vars = set_new ();
|
|
// mark all global vars (except .return and .param_N)
|
|
for (i = num_flow_params; i < func->num_vars; i++) {
|
|
if (flowvar_is_global (func->vars[i]))
|
|
set_add (func->global_vars, i);
|
|
}
|
|
// Put the local varibals in their place (set var->defined to the addresses
|
|
// spanned by the var)
|
|
for (i = 0; i < func->num_vars; i++) {
|
|
int j;
|
|
|
|
var = func->vars[i];
|
|
if (flowvar_is_global (var) || flowvar_is_param (var)) {
|
|
continue;
|
|
}
|
|
for (j = 0; j < var->op->size; j++) {
|
|
set_add (var->define, var->flowaddr + j);
|
|
}
|
|
}
|
|
|
|
set_delete (stuse);
|
|
set_delete (stdef);
|
|
}
|
|
|
|
/** Add the tempop's spanned addresses to the kill set
|
|
*/
|
|
static int
|
|
flow_tempop_kill_aliases (tempop_t *tempop, void *_kill)
|
|
{
|
|
set_t *kill = (set_t *) _kill;
|
|
flowvar_t *var;
|
|
var = tempop->flowvar;
|
|
if (var)
|
|
set_union (kill, var->define);
|
|
return 0;
|
|
}
|
|
|
|
/** Add the def's spanned addresses to the kill set
|
|
*/
|
|
static int
|
|
flow_def_kill_aliases (def_t *def, void *_kill)
|
|
{
|
|
set_t *kill = (set_t *) _kill;
|
|
flowvar_t *var;
|
|
var = def->flowvar;
|
|
if (var)
|
|
set_union (kill, var->define);
|
|
return 0;
|
|
}
|
|
|
|
/** Add the flowvar's spanned addresses to the kill set
|
|
*
|
|
* If the flowvar refers to an alias, then the real def/tempop and any
|
|
* overlapping aliases are aslo killed.
|
|
*
|
|
* However, other aliases cannot kill anything in the uninitialized set.
|
|
*/
|
|
static void
|
|
flow_kill_aliases (set_t *kill, flowvar_t *var, const set_t *uninit)
|
|
{
|
|
operand_t *op;
|
|
set_t *tmp;
|
|
|
|
set_union (kill, var->define);
|
|
op = var->op;
|
|
tmp = set_new ();
|
|
// collect the kill sets from any aliases
|
|
if (op->op_type == op_temp) {
|
|
tempop_visit_all (&op->o.tempop, 1, flow_tempop_kill_aliases, tmp);
|
|
} else if (op->op_type == op_def) {
|
|
def_visit_all (op->o.def, 1, flow_def_kill_aliases, tmp);
|
|
}
|
|
// don't allow aliases to kill definitions in the entry dummy block
|
|
if (uninit) {
|
|
set_difference (tmp, uninit);
|
|
}
|
|
// merge the alias kills with the current def's kills
|
|
set_union (kill, tmp);
|
|
}
|
|
|
|
/** Compute reaching defs
|
|
*/
|
|
static void
|
|
flow_reaching_defs (flowgraph_t *graph)
|
|
{
|
|
int i;
|
|
int changed;
|
|
flownode_t *node;
|
|
statement_t *st;
|
|
set_t *stdef = set_new ();
|
|
set_t *stgen = set_new ();
|
|
set_t *stkill = set_new ();
|
|
set_t *oldout = set_new ();
|
|
set_t *gen, *kill, *in, *out, *uninit;
|
|
set_iter_t *var_i;
|
|
set_iter_t *pred_i;
|
|
flowvar_t *var;
|
|
|
|
// First, create out for the entry dummy node using fake statement numbers.
|
|
//\f[ \bigcup\limits_{i=1}^{\infty} F_{i} \f]
|
|
//\f[ \bigcap\limits_{i=1}^{\infty} F_{i} \f]
|
|
|
|
/** The dummy entry node reaching defs \a out set is initialized to:
|
|
* \f[ out_{reaching}=[\bigcup\limits_{v \in \{locals\}} define_{v}]
|
|
* \setminus \{statements\} \f]
|
|
* where {\a locals} is the set of local def and tempop flowvars (does
|
|
* not include parameters), \a define is the set of addresses spanned
|
|
* by the flowvar (see flow_build_vars()) (XXX along with statement
|
|
* gens), and {\a statements} is the set of all statements in the
|
|
* function (ensures the \a out set does not include any initializers in
|
|
* the code nodes).
|
|
*
|
|
* All other entry node sets are initialized to empty.
|
|
*/
|
|
// kill represents the set of all statements in the function
|
|
kill = set_new ();
|
|
for (i = 0; i < graph->func->num_statements; i++)
|
|
set_add (kill, i);
|
|
// uninit
|
|
uninit = set_new ();
|
|
for (i = 0; i < graph->func->num_vars; i++) {
|
|
var = graph->func->vars[i];
|
|
set_union (uninit, var->define);// do not want alias handling here
|
|
}
|
|
/** Any possible gens from the function code are removed from the
|
|
* \a uninit set (which becomes the \a out set of the entry node's
|
|
* reaching defs) in order to prevent them leaking into the real nodes.
|
|
*/
|
|
set_difference (uninit, kill); // remove any gens from the function
|
|
// initialize the reaching defs sets in the entry node
|
|
graph->nodes[graph->num_nodes]->reaching_defs.out = uninit;
|
|
graph->nodes[graph->num_nodes]->reaching_defs.in = set_new ();
|
|
graph->nodes[graph->num_nodes]->reaching_defs.gen = set_new ();
|
|
graph->nodes[graph->num_nodes]->reaching_defs.kill = set_new ();
|
|
|
|
// Calculate gen and kill for each block, and initialize in and out
|
|
for (i = 0; i < graph->num_nodes; i++) {
|
|
node = graph->nodes[i];
|
|
gen = set_new ();
|
|
kill = set_new ();
|
|
for (st = node->sblock->statements; st; st = st->next) {
|
|
flow_analyze_statement (st, 0, stdef, 0, 0);
|
|
set_empty (stgen);
|
|
set_empty (stkill);
|
|
for (var_i = set_first (stdef); var_i; var_i = set_next (var_i)) {
|
|
var = graph->func->vars[var_i->element];
|
|
flow_kill_aliases (stkill, var, uninit);
|
|
set_remove (stkill, st->number);
|
|
set_add (stgen, st->number);
|
|
}
|
|
|
|
set_difference (gen, stkill);
|
|
set_union (gen, stgen);
|
|
|
|
set_difference (kill, stgen);
|
|
set_union (kill, stkill);
|
|
}
|
|
node->reaching_defs.gen = gen;
|
|
node->reaching_defs.kill = kill;
|
|
node->reaching_defs.in = set_new ();
|
|
node->reaching_defs.out = set_new ();
|
|
}
|
|
|
|
changed = 1;
|
|
while (changed) {
|
|
changed = 0;
|
|
// flow down the graph
|
|
for (i = 0; i < graph->num_nodes; i++) {
|
|
node = graph->nodes[graph->depth_first[i]];
|
|
in = node->reaching_defs.in;
|
|
out = node->reaching_defs.out;
|
|
gen = node->reaching_defs.gen;
|
|
kill = node->reaching_defs.kill;
|
|
for (pred_i = set_first (node->predecessors); pred_i;
|
|
pred_i = set_next (pred_i)) {
|
|
flownode_t *pred = graph->nodes[pred_i->element];
|
|
set_union (in, pred->reaching_defs.out);
|
|
}
|
|
set_assign (oldout, out);
|
|
set_assign (out, in);
|
|
set_difference (out, kill);
|
|
set_union (out, gen);
|
|
if (!set_is_equivalent (out, oldout))
|
|
changed = 1;
|
|
}
|
|
}
|
|
set_delete (oldout);
|
|
set_delete (stdef);
|
|
set_delete (stgen);
|
|
set_delete (stkill);
|
|
}
|
|
|
|
/** Update the node's \a use set from the statement's \a use set
|
|
*/
|
|
static void
|
|
live_set_use (set_t *stuse, set_t *use, set_t *def)
|
|
{
|
|
// the variable is used before it is defined
|
|
set_difference (stuse, def);
|
|
set_union (use, stuse);
|
|
}
|
|
|
|
/** Update the node's \a def set from the statement's \a def set
|
|
*/
|
|
static void
|
|
live_set_def (set_t *stdef, set_t *use, set_t *def)
|
|
{
|
|
// the variable is defined before it is used
|
|
set_difference (stdef, use);
|
|
set_union (def, stdef);
|
|
}
|
|
|
|
static void
|
|
flow_live_vars (flowgraph_t *graph)
|
|
{
|
|
int i, j;
|
|
flownode_t *node;
|
|
set_t *use;
|
|
set_t *def;
|
|
set_t *stuse = set_new ();
|
|
set_t *stdef = set_new ();
|
|
set_t *tmp = set_new ();
|
|
set_iter_t *succ;
|
|
statement_t *st;
|
|
int changed = 1;
|
|
|
|
// 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);
|
|
live_set_def (stdef, use, def);
|
|
}
|
|
node->live_vars.use = use;
|
|
node->live_vars.def = def;
|
|
node->live_vars.in = set_new ();
|
|
node->live_vars.out = set_new ();
|
|
}
|
|
// create in for the exit dummy block using the global vars used by the
|
|
// function
|
|
use = set_new ();
|
|
set_assign (use, graph->func->global_vars);
|
|
node = graph->nodes[graph->num_nodes + 1];
|
|
node->live_vars.in = use;
|
|
node->live_vars.out = set_new ();
|
|
node->live_vars.use = set_new ();
|
|
node->live_vars.def = set_new ();
|
|
|
|
while (changed) {
|
|
changed = 0;
|
|
// flow UP the graph because live variable analysis uses information
|
|
// from a node's successors rather than its predecessors.
|
|
for (j = graph->num_nodes - 1; j >= 0; j--) {
|
|
node = graph->nodes[graph->depth_first[j]];
|
|
set_empty (tmp);
|
|
for (succ = set_first (node->successors); succ;
|
|
succ = set_next (succ))
|
|
set_union (tmp, graph->nodes[succ->element]->live_vars.in);
|
|
if (!set_is_equivalent (node->live_vars.out, tmp)) {
|
|
changed = 1;
|
|
set_assign (node->live_vars.out, tmp);
|
|
}
|
|
set_assign (node->live_vars.in, node->live_vars.out);
|
|
set_difference (node->live_vars.in, node->live_vars.def);
|
|
set_union (node->live_vars.in, node->live_vars.use);
|
|
}
|
|
}
|
|
set_delete (stuse);
|
|
set_delete (stdef);
|
|
set_delete (tmp);
|
|
}
|
|
|
|
static void
|
|
flow_uninit_scan_statements (flownode_t *node, set_t *defs, set_t *uninit)
|
|
{
|
|
set_t *stuse;
|
|
set_t *stdef;
|
|
statement_t *st;
|
|
set_iter_t *var_i;
|
|
flowvar_t *var;
|
|
operand_t *op;
|
|
|
|
// defs holds only reaching definitions. make it hold only reaching
|
|
// uninitialized definitions
|
|
set_intersection (defs, uninit);
|
|
stuse = set_new ();
|
|
stdef = set_new ();
|
|
for (st = node->sblock->statements; st; st = st->next) {
|
|
flow_analyze_statement (st, stuse, stdef, 0, 0);
|
|
for (var_i = set_first (stuse); var_i; var_i = set_next (var_i)) {
|
|
var = node->graph->func->vars[var_i->element];
|
|
if (set_is_intersecting (defs, var->define)) {
|
|
def_t *def = flowvar_get_def (var);
|
|
if (def) {
|
|
if (options.warnings.uninited_variable) {
|
|
warning (st->expr, "%s may be used uninitialized",
|
|
def->name);
|
|
}
|
|
} else {
|
|
bug (st->expr, "st %d, uninitialized temp %s",
|
|
st->number, operand_string (var->op));
|
|
}
|
|
}
|
|
// avoid repeat warnings in this node
|
|
set_difference (defs, var->define);
|
|
}
|
|
for (var_i = set_first (stdef); var_i; var_i = set_next (var_i)) {
|
|
var = node->graph->func->vars[var_i->element];
|
|
// kill any reaching uninitialized definitions for this variable
|
|
set_difference (defs, var->define);
|
|
if (var->op->op_type == op_temp) {
|
|
op = var->op;
|
|
if (op->o.tempop.alias) {
|
|
var = op->o.tempop.alias->o.tempop.flowvar;
|
|
if (var)
|
|
set_difference (defs, var->define);
|
|
}
|
|
for (op = op->o.tempop.alias_ops; op; op = op->next) {
|
|
var = op->o.tempop.flowvar;
|
|
if (var)
|
|
set_difference (defs, var->define);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
set_delete (stuse);
|
|
set_delete (stdef);
|
|
}
|
|
|
|
static void
|
|
flow_uninitialized (flowgraph_t *graph)
|
|
{
|
|
int i;
|
|
flownode_t *node;
|
|
flowvar_t *var;
|
|
set_iter_t *var_i;
|
|
set_t *defs;
|
|
set_t *uninitialized;
|
|
|
|
uninitialized = set_new ();
|
|
node = graph->nodes[graph->num_nodes];
|
|
set_assign (uninitialized, node->reaching_defs.out);
|
|
defs = set_new ();
|
|
|
|
for (i = 0; i < graph->num_nodes; i++) {
|
|
node = graph->nodes[graph->depth_first[i]];
|
|
set_empty (defs);
|
|
// collect definitions of all variables "used" in this node. use from
|
|
// the live vars analysis is perfect for the job
|
|
for (var_i = set_first (node->live_vars.use); var_i;
|
|
var_i = set_next (var_i)) {
|
|
var = graph->func->vars[var_i->element];
|
|
set_union (defs, var->define);
|
|
}
|
|
// interested in only those defintions that actually reach this node
|
|
set_intersection (defs, node->reaching_defs.in);
|
|
// if any of the definitions come from the entry dummy block, then
|
|
// the statements need to be scanned in case an aliasing definition
|
|
// kills the dummy definition before the usage, and also so the line
|
|
// number information can be obtained from the statement.
|
|
if (set_is_intersecting (defs, uninitialized))
|
|
flow_uninit_scan_statements (node, defs, uninitialized);
|
|
}
|
|
set_delete (defs);
|
|
}
|
|
|
|
static void
|
|
flow_build_dags (flowgraph_t *graph)
|
|
{
|
|
int i;
|
|
flownode_t *node;
|
|
|
|
for (i = 0; i < graph->num_nodes; i++) {
|
|
node = graph->nodes[i];
|
|
node->dag = dag_create (node);
|
|
}
|
|
if (options.block_dot.dags)
|
|
dump_dot ("dags", graph, dump_dot_flow_dags);
|
|
}
|
|
|
|
static void
|
|
flow_cleanup_dags (flowgraph_t *graph)
|
|
{
|
|
int i;
|
|
flownode_t *node;
|
|
|
|
for (i = 0; i < graph->num_nodes; i++) {
|
|
node = graph->nodes[i];
|
|
dag_remove_dead_nodes (node->dag);
|
|
}
|
|
if (options.block_dot.dags)
|
|
dump_dot ("cleaned-dags", graph, dump_dot_flow_dags);
|
|
}
|
|
|
|
static sblock_t *
|
|
flow_generate (flowgraph_t *graph)
|
|
{
|
|
int i;
|
|
sblock_t *code = 0;
|
|
sblock_t **tail = &code;
|
|
|
|
for (i = 0; i < graph->num_nodes; i++) {
|
|
ex_label_t *label;
|
|
sblock_t *block;
|
|
|
|
flownode_t *node = graph->nodes[i];
|
|
*tail = block = new_sblock ();
|
|
tail = &(*tail)->next;
|
|
// first, transfer any labels on the old node to the new
|
|
while ((label = node->sblock->labels)) {
|
|
node->sblock->labels = label->next;
|
|
label->next = block->labels;
|
|
block->labels = label;
|
|
label->dest = block;
|
|
}
|
|
// generate new statements from the dag;
|
|
dag_generate (node->dag, block);
|
|
}
|
|
if (options.block_dot.post)
|
|
dump_dot ("post", code, dump_dot_sblock);
|
|
return code;
|
|
}
|
|
|
|
static int
|
|
flow_tempop_add_aliases (tempop_t *tempop, void *_set)
|
|
{
|
|
set_t *set = (set_t *) _set;
|
|
flowvar_t *var;
|
|
var = tempop->flowvar;
|
|
if (var)
|
|
set_add (set, var->number);
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
flow_def_add_aliases (def_t *def, void *_set)
|
|
{
|
|
set_t *set = (set_t *) _set;
|
|
flowvar_t *var;
|
|
var = def->flowvar;
|
|
if (var)
|
|
set_add (set, var->number);
|
|
return 0;
|
|
}
|
|
|
|
static void
|
|
flow_add_op_var (set_t *set, operand_t *op, int is_use)
|
|
{
|
|
flowvar_t *var;
|
|
int ol = is_use ? 1 : 2;
|
|
|
|
if (!set)
|
|
return;
|
|
if (!(var = flow_get_var (op)))
|
|
return;
|
|
set_add (set, var->number);
|
|
|
|
// FIXME XXX I think the curent implementation will have problems
|
|
// for the def set when assigning to an alias as right now the real
|
|
// var is being treated as assigned as well. Want to handle partial
|
|
// defs properly, but I am as yet uncertain of how.
|
|
if (op->op_type == op_temp) {
|
|
tempop_visit_all (&op->o.tempop, ol, flow_tempop_add_aliases, set);
|
|
} else {
|
|
def_visit_all (op->o.def, ol, flow_def_add_aliases, set);
|
|
}
|
|
}
|
|
|
|
static operand_t *
|
|
flow_analyze_pointer_operand (operand_t *ptrop, set_t *def)
|
|
{
|
|
operand_t *op = 0;
|
|
|
|
if (ptrop->op_type == op_value && ptrop->o.value->lltype == ev_pointer) {
|
|
ex_pointer_t *ptr = &ptrop->o.value->v.pointer;
|
|
if (ptrop->o.value->v.pointer.def) {
|
|
def_t *alias;
|
|
alias = alias_def (ptr->def, ptr->type, ptr->val);
|
|
op = def_operand (alias, ptr->type, ptrop->expr);
|
|
}
|
|
if (ptrop->o.value->v.pointer.tempop) {
|
|
op = ptrop->o.value->v.pointer.tempop;
|
|
}
|
|
if (op) {
|
|
flow_add_op_var (def, op, 0);
|
|
}
|
|
}
|
|
return op;
|
|
}
|
|
|
|
void
|
|
flow_analyze_statement (statement_t *s, set_t *use, set_t *def, set_t *kill,
|
|
operand_t *operands[FLOW_OPERANDS])
|
|
{
|
|
int i, start, calln = -1;
|
|
operand_t *res_op = 0;
|
|
operand_t *aux_op1 = 0;
|
|
operand_t *aux_op2 = 0;
|
|
|
|
if (use)
|
|
set_empty (use);
|
|
if (def)
|
|
set_empty (def);
|
|
if (kill)
|
|
set_empty (kill);
|
|
if (operands) {
|
|
for (i = 0; i < FLOW_OPERANDS; i++)
|
|
operands[i] = 0;
|
|
}
|
|
|
|
switch (s->type) {
|
|
case st_none:
|
|
internal_error (s->expr, "not a statement");
|
|
case st_expr:
|
|
flow_add_op_var (def, s->opc, 0);
|
|
flow_add_op_var (use, s->opa, 1);
|
|
if (s->opb)
|
|
flow_add_op_var (use, s->opb, 1);
|
|
if (operands) {
|
|
operands[0] = s->opc;
|
|
operands[1] = s->opa;
|
|
operands[2] = s->opb;
|
|
}
|
|
break;
|
|
case st_assign:
|
|
flow_add_op_var (def, s->opb, 0);
|
|
flow_add_op_var (use, s->opa, 1);
|
|
if (operands) {
|
|
operands[0] = s->opb;
|
|
operands[1] = s->opa;
|
|
}
|
|
break;
|
|
case st_ptrassign:
|
|
case st_move:
|
|
case st_ptrmove:
|
|
case st_memset:
|
|
case st_ptrmemset:
|
|
flow_add_op_var (use, s->opa, 1);
|
|
flow_add_op_var (use, s->opb, 1);
|
|
if (!strcmp (s->opcode, "<MOVE>")
|
|
|| !strcmp (s->opcode, "<MEMSET>")) {
|
|
flow_add_op_var (def, s->opc, 0);
|
|
res_op = s->opc;
|
|
} else if (!strcmp (s->opcode, "<MOVEP>")) {
|
|
flow_add_op_var (use, s->opc, 0);
|
|
aux_op2 = flow_analyze_pointer_operand (s->opa, use);
|
|
res_op = flow_analyze_pointer_operand (s->opc, def);
|
|
aux_op1 = s->opc;
|
|
} else if (!strcmp (s->opcode, "<MEMSETP>")) {
|
|
flow_add_op_var (use, s->opc, 0);
|
|
res_op = flow_analyze_pointer_operand (s->opc, def);
|
|
aux_op1 = s->opc;
|
|
} else if (!strcmp (s->opcode, ".=")) {
|
|
flow_add_op_var (use, s->opc, 1);
|
|
res_op = flow_analyze_pointer_operand (s->opb, def);
|
|
aux_op1 = s->opc;
|
|
} else {
|
|
internal_error (s->expr, "unexpected opcode '%s' for %d",
|
|
s->opcode, s->type);
|
|
}
|
|
if (kill) {
|
|
set_everything (kill);
|
|
}
|
|
if (operands) {
|
|
operands[0] = res_op;
|
|
operands[1] = s->opa;
|
|
operands[2] = s->opb;
|
|
operands[3] = aux_op1;
|
|
operands[4] = aux_op2;
|
|
}
|
|
break;
|
|
case st_state:
|
|
flow_add_op_var (use, s->opa, 1);
|
|
flow_add_op_var (use, s->opb, 1);
|
|
if (s->opc)
|
|
flow_add_op_var (use, s->opc, 1);
|
|
//FIXME entity members
|
|
if (operands) {
|
|
operands[1] = s->opa;
|
|
operands[2] = s->opb;
|
|
operands[3] = s->opc;
|
|
}
|
|
break;
|
|
case st_func:
|
|
if (strcmp (s->opcode, "<RETURN>") == 0
|
|
|| strcmp (s->opcode, "<DONE>") == 0) {
|
|
flow_add_op_var (use, s->opa, 1);
|
|
} else if (strcmp (s->opcode, "<RETURN_V>") == 0) {
|
|
if (use) {
|
|
flow_add_op_var (use, &flow_params[0].op, 1);
|
|
}
|
|
}
|
|
if (strncmp (s->opcode, "<CALL", 5) == 0) {
|
|
start = 0;
|
|
calln = s->opcode[5] - '0';
|
|
flow_add_op_var (use, s->opa, 1);
|
|
} else if (strncmp (s->opcode, "<RCALL", 6) == 0) {
|
|
start = 2;
|
|
calln = s->opcode[6] - '0';
|
|
flow_add_op_var (use, s->opa, 1);
|
|
flow_add_op_var (use, s->opb, 1);
|
|
if (s->opc)
|
|
flow_add_op_var (use, s->opc, 1);
|
|
}
|
|
if (calln >= 0) {
|
|
if (use) {
|
|
for (i = start; i < calln; i++) {
|
|
flow_add_op_var (use, &flow_params[i + 1].op, 1);
|
|
}
|
|
}
|
|
if (def) {
|
|
for (i = 0; i < num_flow_params; i++) {
|
|
flow_add_op_var (def, &flow_params[i].op, 0);
|
|
}
|
|
}
|
|
if (kill) {
|
|
for (i = 0; i < num_flow_params; i++) {
|
|
flow_kill_aliases (kill,
|
|
flow_get_var (&flow_params[i].op),
|
|
0);
|
|
}
|
|
}
|
|
}
|
|
if (operands) {
|
|
operands[1] = s->opa;
|
|
operands[2] = s->opb;
|
|
operands[3] = s->opc;
|
|
}
|
|
break;
|
|
case st_flow:
|
|
if (strcmp (s->opcode, "<GOTO>") != 0) {
|
|
flow_add_op_var (use, s->opa, 1);
|
|
if (strcmp (s->opcode, "<JUMPB>") == 0)
|
|
flow_add_op_var (use, s->opb, 1);
|
|
}
|
|
if (operands) {
|
|
operands[1] = s->opa;
|
|
operands[2] = s->opb;
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
|
|
static void
|
|
flow_find_successors (flowgraph_t *graph)
|
|
{
|
|
int i;
|
|
flownode_t *node;
|
|
sblock_t *sb;
|
|
statement_t *st;
|
|
sblock_t **target_list, **target;
|
|
|
|
// "convert" the basic blocks connections to flow-graph connections
|
|
for (i = 0; i < graph->num_nodes + 2; i++) {
|
|
node = graph->nodes[i];
|
|
set_empty (node->successors);
|
|
set_empty (node->predecessors);
|
|
set_empty (node->edges);
|
|
}
|
|
graph->num_edges = 0;
|
|
|
|
for (i = 0; i < graph->num_nodes; i++) {
|
|
node = graph->nodes[i];
|
|
sb = node->sblock;
|
|
st = 0;
|
|
if (sb->statements)
|
|
st = (statement_t *) sb->tail;
|
|
//NOTE: if st is null (the sblock has no statements), statement_is_*
|
|
//will return false
|
|
//FIXME jump/jumpb
|
|
if (statement_is_goto (st) || statement_is_jumpb (st)) {
|
|
// sb's next is never followed.
|
|
target_list = statement_get_targetlist (st);
|
|
for (target = target_list; *target; target++)
|
|
set_add (node->successors, (*target)->flownode->id);
|
|
free (target_list);
|
|
} else if (statement_is_cond (st)) {
|
|
// branch: either sb's next or the conditional statment's
|
|
// target will be followed.
|
|
set_add (node->successors, sb->next->flownode->id);
|
|
target_list = statement_get_targetlist (st);
|
|
for (target = target_list; *target; target++)
|
|
set_add (node->successors, (*target)->flownode->id);
|
|
free (target_list);
|
|
} else if (statement_is_return (st)) {
|
|
// exit from function (dead end)
|
|
// however, make the exit dummy block the node's successor
|
|
set_add (node->successors, graph->num_nodes + 1);
|
|
} else {
|
|
// there is no flow-control statement in sb, so sb's next
|
|
// must be followed
|
|
if (sb->next) {
|
|
set_add (node->successors, sb->next->flownode->id);
|
|
} else {
|
|
bug (st->expr, "code drops off the end of the function");
|
|
// this shouldn't happen
|
|
// however, make the exit dummy block the node's successor
|
|
set_add (node->successors, graph->num_nodes + 1);
|
|
}
|
|
}
|
|
graph->num_edges += set_size (node->successors);
|
|
}
|
|
// set the successor for the entry dummy node to the real entry node
|
|
node = graph->nodes[graph->num_nodes];
|
|
set_add (node->successors, 0);
|
|
graph->num_edges += set_size (node->successors);
|
|
}
|
|
|
|
static void
|
|
flow_make_edges (flowgraph_t *graph)
|
|
{
|
|
int i, j;
|
|
flownode_t *node;
|
|
set_iter_t *succ;
|
|
|
|
if (graph->edges)
|
|
free (graph->edges);
|
|
graph->edges = malloc (graph->num_edges * sizeof (flowedge_t));
|
|
for (j = 0, i = 0; i < graph->num_nodes + 2; i++) {
|
|
node = graph->nodes[i];
|
|
for (succ = set_first (node->successors); succ;
|
|
succ = set_next (succ), j++) {
|
|
set_add (node->edges, j);
|
|
graph->edges[j].tail = i;
|
|
graph->edges[j].head = succ->element;
|
|
}
|
|
}
|
|
}
|
|
|
|
static void
|
|
flow_find_predecessors (flowgraph_t *graph)
|
|
{
|
|
int i;
|
|
flownode_t *node;
|
|
set_iter_t *succ;
|
|
|
|
for (i = 0; i < graph->num_nodes + 2; i++) {
|
|
node = graph->nodes[i];
|
|
for (succ = set_first (node->successors); succ;
|
|
succ = set_next (succ)) {
|
|
set_add (graph->nodes[succ->element]->predecessors, i);
|
|
}
|
|
}
|
|
}
|
|
|
|
static void
|
|
flow_find_dominators (flowgraph_t *graph)
|
|
{
|
|
set_t *work;
|
|
flownode_t *node;
|
|
int i;
|
|
set_iter_t *pred;
|
|
int changed;
|
|
|
|
if (!graph->num_nodes)
|
|
return;
|
|
|
|
// First, create a base set for the initial state of the non-initial nodes
|
|
work = set_new ();
|
|
for (i = 0; i < graph->num_nodes; i++)
|
|
set_add (work, i);
|
|
|
|
set_add (graph->nodes[0]->dom, 0);
|
|
|
|
// initialize dom for the non-initial nodes
|
|
for (i = 1; i < graph->num_nodes; i++) {
|
|
set_assign (graph->nodes[i]->dom, work);
|
|
}
|
|
|
|
do {
|
|
changed = 0;
|
|
for (i = 1; i < graph->num_nodes; i++) {
|
|
node = graph->nodes[i];
|
|
set_empty (work);
|
|
for (pred = set_first (node->predecessors); pred;
|
|
pred = set_next (pred))
|
|
set_intersection (work, graph->nodes[pred->element]->dom);
|
|
set_add (work, i);
|
|
if (!set_is_equivalent (work, node->dom))
|
|
changed = 1;
|
|
set_assign (node->dom, work);
|
|
}
|
|
} while (changed);
|
|
set_delete (work);
|
|
}
|
|
|
|
static void
|
|
insert_loop_node (flowloop_t *loop, unsigned n, set_t *stack)
|
|
{
|
|
if (!set_is_member (loop->nodes, n)) {
|
|
set_add (loop->nodes, n);
|
|
set_add (stack, n);
|
|
}
|
|
}
|
|
|
|
static flowloop_t *
|
|
make_loop (flowgraph_t *graph, unsigned n, unsigned d)
|
|
{
|
|
flowloop_t *loop = new_loop ();
|
|
flownode_t *node;
|
|
set_t *stack = set_new ();
|
|
set_iter_t *pred;
|
|
|
|
loop->head = d;
|
|
set_add (loop->nodes, d);
|
|
insert_loop_node (loop, n, stack);
|
|
while (!set_is_empty (stack)) {
|
|
set_iter_t *ss = set_first (stack);
|
|
unsigned m = ss->element;
|
|
set_del_iter (ss);
|
|
set_remove (stack, m);
|
|
node = graph->nodes[m];
|
|
for (pred = set_first (node->predecessors); pred;
|
|
pred = set_next (pred))
|
|
insert_loop_node (loop, pred->element, stack);
|
|
}
|
|
set_delete (stack);
|
|
return loop;
|
|
}
|
|
|
|
static void
|
|
flow_find_loops (flowgraph_t *graph)
|
|
{
|
|
flownode_t *node;
|
|
set_iter_t *succ;
|
|
flowloop_t *loop, *l;
|
|
flowloop_t *loop_list = 0;
|
|
int i;
|
|
|
|
for (i = 0; i < graph->num_nodes; i++) {
|
|
node = graph->nodes[i];
|
|
for (succ = set_first (node->successors); succ;
|
|
succ = set_next (succ)) {
|
|
if (set_is_member (node->dom, succ->element)) {
|
|
loop = make_loop (graph, node->id, succ->element);
|
|
for (l = loop_list; l; l = l->next) {
|
|
if (l->head == loop->head
|
|
&& !set_is_subset (l->nodes, loop->nodes)
|
|
&& !set_is_subset (loop->nodes, l->nodes)) {
|
|
set_union (l->nodes, loop->nodes);
|
|
delete_loop (loop);
|
|
loop = 0;
|
|
break;
|
|
}
|
|
}
|
|
if (loop) {
|
|
loop->next = loop_list;
|
|
loop_list = loop;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
graph->loops = loop_list;
|
|
}
|
|
|
|
static void
|
|
df_search (flowgraph_t *graph, set_t *visited, int *i, int n)
|
|
{
|
|
flownode_t *node;
|
|
set_iter_t *edge;
|
|
int succ;
|
|
|
|
set_add (visited, n);
|
|
node = graph->nodes[n];
|
|
for (edge = set_first (node->edges); edge; edge = set_next (edge)) {
|
|
succ = graph->edges[edge->element].head;
|
|
if (!set_is_member (visited, succ)) {
|
|
set_add (graph->dfst, edge->element);
|
|
df_search (graph, visited, i, succ);
|
|
}
|
|
}
|
|
node->dfn = --*i;
|
|
graph->depth_first[node->dfn] = n;
|
|
}
|
|
|
|
static void
|
|
flow_build_dfst (flowgraph_t *graph)
|
|
{
|
|
set_t *visited = set_new ();
|
|
int i;
|
|
|
|
// mark the dummy nodes as visited to keep them out of the dfst
|
|
set_add (visited, graph->num_nodes);
|
|
set_add (visited, graph->num_nodes + 1);
|
|
|
|
if (graph->depth_first)
|
|
free (graph->depth_first);
|
|
if (graph->dfst)
|
|
set_delete (graph->dfst);
|
|
graph->depth_first = calloc (graph->num_nodes, sizeof (int));
|
|
graph->dfst = set_new ();
|
|
i = graph->num_nodes;
|
|
df_search (graph, visited, &i, 0);
|
|
set_delete (visited);
|
|
}
|
|
|
|
static int
|
|
flow_remove_unreachable_nodes (flowgraph_t *graph)
|
|
{
|
|
int i, j;
|
|
flownode_t *node;
|
|
|
|
for (i = 0, j = 0; i < graph->num_nodes; i++) {
|
|
node = graph->nodes[i];
|
|
if (node->dfn < 0) // skip over unreachable nodes
|
|
continue;
|
|
node->id = j; // new node number
|
|
graph->nodes[j++] = node;
|
|
}
|
|
graph->nodes[j] = graph->nodes[i]; // copy entry dummy node
|
|
graph->nodes[j + 1] = graph->nodes[i + 1]; // copy exit dummy node
|
|
|
|
// kill the pointers to unreachable nodes
|
|
for (i = j; i < graph->num_nodes; i++)
|
|
graph->nodes[i + 2] = 0;
|
|
|
|
if (j < graph->num_nodes) {
|
|
graph->num_nodes = j;
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static flownode_t *
|
|
flow_make_node (sblock_t *sblock, int id, function_t *func)
|
|
{
|
|
flownode_t *node;
|
|
|
|
node = new_node ();
|
|
node->predecessors = set_new ();
|
|
node->successors = set_new ();
|
|
node->edges = set_new ();
|
|
node->dom = set_new ();
|
|
node->global_vars = func->global_vars;
|
|
node->id = id;
|
|
node->sblock = sblock;
|
|
if (sblock)
|
|
sblock->flownode = node;
|
|
node->graph = func->graph;
|
|
// Mark the node as unreachable. flow_build_dfst() will mark reachable
|
|
// nodes with a value >= 0
|
|
node->dfn = -1;
|
|
return node;
|
|
}
|
|
|
|
/** Build the flow graph for the function.
|
|
*
|
|
* In addition to the nodes create by the statement blocks, there are two
|
|
* dummy blocks:
|
|
*
|
|
* \dot
|
|
* digraph flow_build_graph {
|
|
* layout = dot; rankdir = TB; compound =true; nodesp = 1.0;
|
|
* dummy_entry [shape=box,label="entry"];
|
|
* sblock0 [label="code"]; sblock1 [label="code"];
|
|
* sblock2 [label="code"]; sblock3 [label="code"];
|
|
* dummy_exit [shape=box,label="exit"];
|
|
* dummy_entry -> sblock0; sblock0 -> sblock1;
|
|
* sblock1 -> sblock2; sblock2 -> sblock1;
|
|
* sblock2 -> dummy_exit; sblock1 -> sblock3;
|
|
* sblock3 -> dummy_exit;
|
|
* }
|
|
* \enddot
|
|
*
|
|
* The entry block is used for detecting use of uninitialized local variables
|
|
* and the exit block is used for ensuring global variables are treated as
|
|
* live at function exit.
|
|
*
|
|
* The exit block, which also is empty of statements, has its live vars
|
|
* \a use set initilized to the set of global defs, which are simply numbered
|
|
* by their index in the functions list of flowvars. All other exit node sets
|
|
* are initialized to empty.
|
|
* \f[ use_{live}=globals \f]
|
|
*/
|
|
static flowgraph_t *
|
|
flow_build_graph (function_t *func)
|
|
{
|
|
sblock_t *sblock = func->sblock;
|
|
flowgraph_t *graph;
|
|
flownode_t *node;
|
|
sblock_t *sb;
|
|
int i;
|
|
int pass = 0;
|
|
|
|
graph = new_graph ();
|
|
graph->func = func;
|
|
func->graph = graph;
|
|
for (sb = sblock; sb; sb = sb->next)
|
|
graph->num_nodes++;
|
|
// + 2 for the uninitialized dummy head block and the live dummy end block
|
|
graph->nodes = malloc ((graph->num_nodes + 2) * sizeof (flownode_t *));
|
|
for (i = 0, sb = sblock; sb; i++, sb = sb->next)
|
|
graph->nodes[i] = flow_make_node (sb, i, func);
|
|
// Create the dummy node for detecting uninitialized variables
|
|
node = flow_make_node (0, graph->num_nodes, func);
|
|
graph->nodes[graph->num_nodes] = node;
|
|
// Create the dummy node for making global vars live at function exit
|
|
node = flow_make_node (0, graph->num_nodes + 1, func);
|
|
graph->nodes[graph->num_nodes + 1] = node;
|
|
|
|
do {
|
|
if (pass > 1)
|
|
internal_error (0, "too many unreachable node passes");
|
|
flow_find_successors (graph);
|
|
flow_make_edges (graph);
|
|
flow_build_dfst (graph);
|
|
if (options.block_dot.flow)
|
|
dump_dot (va ("flow-%d", pass), graph, dump_dot_flow);
|
|
pass++;
|
|
} while (flow_remove_unreachable_nodes (graph));
|
|
flow_find_predecessors (graph);
|
|
flow_find_dominators (graph);
|
|
flow_find_loops (graph);
|
|
return graph;
|
|
}
|
|
|
|
void
|
|
flow_data_flow (function_t *func)
|
|
{
|
|
flowgraph_t *graph;
|
|
|
|
flow_build_statements (func);
|
|
flow_build_vars (func);
|
|
graph = flow_build_graph (func);
|
|
if (options.block_dot.statements)
|
|
dump_dot ("statements", graph, dump_dot_flow_statements);
|
|
flow_reaching_defs (graph);
|
|
if (options.block_dot.reaching)
|
|
dump_dot ("reaching", graph, dump_dot_flow_reaching);
|
|
flow_live_vars (graph);
|
|
if (options.block_dot.live)
|
|
dump_dot ("live", graph, dump_dot_flow_live);
|
|
flow_uninitialized (graph);
|
|
flow_build_dags (graph);
|
|
flow_cleanup_dags (graph);
|
|
func->sblock = flow_generate (graph);
|
|
}
|
|
|
|
///@}
|