void G_addEdge(G_node from, G_node to) {
assert(from); assert(to);
assert(from->mygraph == to->mygraph);
if (G_goesTo(from, to)) return;
to->preds=G_NodeList(from, to->preds);
from->succs=G_NodeList(to, from->succs);
}
/* generic creation of G_node */
G_node G_Node(G_graph g, void *info)
{G_node n = (G_node)checked_malloc(sizeof *n);
G_nodeList p = G_NodeList(n, NULL);
assert(g);
n->mygraph=g;
n->mykey=g->nodecount++;
if (g->mylast==NULL)
g->mynodes=g->mylast=p;
else g->mylast = g->mylast->tail = p;
n->succs=NULL;
n->preds=NULL;
n->info=info;
return n;
}
G_graph FG_AssemFlowGraph(AS_instrList il) {
UD_init();
//(I) Iterate over the entire instruction list
AS_instr instr = NULL;
G_node prev = NULL;
G_node curr = NULL;
G_graph graph = G_Graph();
G_nodeList jumpList = NULL;
G_nodeList jumpListHead = NULL;
for(; il!=NULL; il=il->tail){
instr = il->head;
if(instr!=NULL){
//1) create a node (and put it into the graph), using the
// instruction as the associated info.
curr = G_Node(graph, instr);
//2) special handling
int type = IT_COMMON;
Temp_tempList defs = NULL;
Temp_tempList uses = NULL;
switch(instr->kind) {
case I_OPER:
// Check if it's a JUMP instruction
// We do this check here by looking if As_target is null,
// instead of inspecting the assembly op (j, beq, ...)
if(instr->u.OPER.jumps!=NULL &&
instr->u.OPER.jumps->labels!=NULL){
type = IT_JUMP;
// put this instruction into a separate list
if(jumpList==NULL){
jumpList = G_NodeList(curr, NULL);
jumpListHead = jumpList;
} else {
jumpList->tail = G_NodeList(curr, NULL);
jumpList = jumpList->tail;
}
}
defs = instr->u.OPER.dst;
uses = instr->u.OPER.src;
break;
case I_LABEL:
//2.2) label should be also saved in the label-node list for (II)
LT_enter(instr->u.LABEL.label, curr);
break;
case I_MOVE:
//2.3) it's a move instruction
type = IT_MOVE;
defs = instr->u.MOVE.dst;
uses = instr->u.MOVE.src;
break;
}
//3) put information into table
UD_enter(curr, UDInfo(uses, defs, type == IT_MOVE));
//4) link with the previous node for falling through, if possible.
// Note that prev is NULL if the previous instruction is a JUMP.
if(prev!=NULL){
G_addEdge(prev, curr);
}
//5) set as previous node for next time of iteration
prev = (type!=IT_JUMP)?curr:NULL;
}
}
//(II) Iterate over the list that has all the JUMP instruction collected.
Temp_labelList labels;
for(; jumpListHead!=NULL; jumpListHead=jumpListHead->tail){
curr = jumpListHead->head;
labels = ((AS_instr)G_nodeInfo(curr))->u.OPER.jumps->labels;//no need to check its nullity again
Temp_label label;
G_node dest;
// for each target it may jump to, add a corresponding edge in the graph
for(;labels!=NULL;labels=labels->tail){
label = labels->head;
if(label!=NULL){
// quickly retieve the target node using the label-node table
dest = LT_lookup(label);
// establish edge between this node and its jump target
G_addEdge(curr, dest);
}
}
}
return graph;
}