Reuse tempary variables.

Now that I've got nice code, it was worth doing. Unfortunatly, bsearch
style switch statements have problems.
switch.r:14: BUG: temp users went negative: <tmp 0x21b6840:-1>
switch.r:14: BUG: temp users went negative: <tmp 0x21b6840:-2>
switch.r:14: BUG: temp users went negative: <tmp 0x21b6840:-3>
switch.r:14: BUG: temp users went negative: <tmp 0x21b67d0:-1>

tools/qfcc/include/def.h

@@ -77,6 +77,7 @@ def_t *new_def (const char *name, struct type_s *type,
 				struct defspace_s *space, storage_class_t storage);
 def_t *alias_def (def_t *def, struct type_s *type);
 def_t *temp_def (etype_t type, int size);
+void free_temp_def (def_t *temp);
 void free_def (def_t *def);
 
 void def_to_ddef (def_t *def, ddef_t *ddef, int aux);

tools/qfcc/include/function.h

@@ -67,6 +67,7 @@ typedef struct function_s {
 	string_t            s_file;		///< source file with definition
 	string_t            s_name;		///< name of function in output
 	int                 temp_num;	///< number for next temp var
+	struct def_s       *temp_defs[4];	///< freed temp vars (by size)
 	struct def_s       *def;		///< output def holding function number
 	struct symbol_s    *sym;		///< internal symbol for this function
 	/** Root scope symbol table of the function.

tools/qfcc/include/statements.h

@@ -45,6 +45,7 @@ typedef struct {
 	struct def_s   *def;
 	struct flowvar_s *flowvar;
 	struct daglabel_s *daglabel;
+	int         users;
 } tempop_t;
 
 typedef struct operand_s {

tools/qfcc/source/dags.c

@@ -498,6 +498,10 @@ make_operand (dag_t *dag, sblock_t *block, const dagnode_t *dagnode, int index)
 	operand_t  *op;
 
 	op = dagnode->children[index]->value;
+	while (op->op_type == op_alias)
+		op = op->o.alias;
+	if (op->op_type == op_temp)
+		op->o.tempop.users++;
 	op = fix_op_type (op, dagnode->types[index]);
 	return op;
 }
@@ -525,6 +529,7 @@ dag_gencode (dag_t *dag, sblock_t *block, dagnode_t *dagnode)
 				operands[1] = make_operand (dag, block, dagnode, 1);
 			if (!(var_iter = set_first (dagnode->identifiers))) {
 				operands[2] = temp_operand (get_type (dagnode->label->expr));
+				operands[2]->o.tempop.users++;
 			} else {
 				daglabel_t *var = dag->labels[var_iter->member];
 				etype_t     type = extract_type (dagnode->label->expr);

tools/qfcc/source/def.c

@@ -162,6 +162,11 @@ temp_def (etype_t type, int size)
 	def_t      *temp;
 	defspace_t *space = current_func->symtab->space;
 
+	if ((temp = current_func->temp_defs[size - 1])) {
+		current_func->temp_defs[size - 1] = temp->next;
+		temp->next = 0;
+		return temp;
+	}
 	ALLOC (16384, def_t, defs, temp);
 	temp->return_addr = __builtin_return_address (0);
 	temp->name = save_string (va (".tmp%d", current_func->temp_num++));
@@ -176,6 +181,14 @@ temp_def (etype_t type, int size)
 	return temp;
 }
 
+void
+free_temp_def (def_t *temp)
+{
+	int         size = type_size (temp->type) - 1;
+	temp->next = current_func->temp_defs[size];
+	current_func->temp_defs[size] = temp;
+}
+
 void
 free_def (def_t *def)
 {

tools/qfcc/source/dot_dag.c

@@ -46,6 +46,7 @@
 #include "dags.h"
 #include "set.h"
 #include "statements.h"
+#include "strpool.h"
 #include "symtab.h"
 #include "type.h"
 
@@ -123,7 +124,7 @@ print_node (dstring_t *dstr, dag_t *dag, dagnode_t *node)
 		for (id_iter = set_first (node->identifiers); id_iter;
 			 id_iter = set_next (id_iter)) {
 			id = dag->labels[id_iter->member];
-			dasprintf (dstr, " %s", daglabel_string(id));
+			dasprintf (dstr, " %s", html_string (daglabel_string(id)));
 		}
 		dasprintf (dstr, "        </td>");
 		dasprintf (dstr, "      </tr>\n");

tools/qfcc/source/emit.c

@@ -171,16 +171,33 @@ add_statement_op_ref (operand_t *op, dstatement_t *st, int field)
 	}
 }
 
+static void
+use_tempop (operand_t *op)
+{
+	if (!op || op->op_type != op_temp)
+		return;
+	if (--op->o.tempop.users == 0)
+		free_temp_def (op->o.tempop.def);
+	if (op->o.tempop.users <= -1)
+		bug (0, "temp users went negative: %s", operand_string (op));
+}
+
 static void
 emit_statement (statement_t *statement)
 {
 	const char *opcode = statement->opcode;
-	def_t      *def_a = get_operand_def (statement->expr, statement->opa);
-	def_t      *def_b = get_operand_def (statement->expr, statement->opb);
-	def_t      *def_c = get_operand_def (statement->expr, statement->opc);
-	opcode_t   *op = opcode_find (opcode, def_a, def_b, def_c);
+	def_t      *def_a, *def_b, *def_c;
+	opcode_t   *op;
 	dstatement_t *s;
 
+	def_a = get_operand_def (statement->expr, statement->opa);
+	use_tempop (statement->opa);
+	def_b = get_operand_def (statement->expr, statement->opb);
+	use_tempop (statement->opb);
+	def_c = get_operand_def (statement->expr, statement->opc);
+	use_tempop (statement->opc);
+	op = opcode_find (opcode, def_a, def_b, def_c);
+
 	if (!op) {
 		print_expr (statement->expr);
 		print_statement (statement);

tools/qfcc/source/flow.c

@@ -435,7 +435,7 @@ flow_generate (flowgraph_t *graph)
 		// generate new statements from the dag;
 		dag_generate (node->dag, block);
 	}
-	//dump_dot ("post", code, dump_dot_sblock);
+	dump_dot ("post", code, dump_dot_sblock);
 	return code;
 }
 

tools/qfcc/source/statements.c

@@ -108,7 +108,7 @@ operand_string (operand_t *op)
 		case op_label:
 			return op->o.label->name;
 		case op_temp:
-			return va ("tmp %p", op);
+			return va ("<tmp %p:%d>", op, op->o.tempop.users);
 		case op_pointer:
 			type = op->o.value->v.pointer.type;
 			if (op->o.value->v.pointer.def)