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22 * @brief conv node optimisation
23 * @author Matthias Braun, Christoph Mallon
26 * Try to minimize the number of conv nodes by changing modes of operations.
27 * The typical example is the following structure:
32 * Add Is gets transformed to |
36 * TODO: * try to optimize cmp modes
37 * * decide when it is useful to move the convs through phis
41 #include "iroptimize.h"
51 #include "iredges_t.h"
57 #include "opt_manage.h"
59 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
61 static inline int imin(int a, int b) { return a < b ? a : b; }
63 static bool is_optimizable_node(const ir_node *node, ir_mode *dest_mode)
65 switch (get_irn_opcode(node)) {
77 int modulo_shift = get_mode_modulo_shift(dest_mode);
78 int old_shift = get_mode_modulo_shift(get_irn_mode(node));
79 /* bail out if modulo shift changes */
80 if (modulo_shift != old_shift)
90 static ir_tarval* conv_const_tv(const ir_node* cnst, ir_mode* dest_mode)
92 return tarval_convert_to(get_Const_tarval(cnst), dest_mode);
95 static int is_downconv(ir_mode *src_mode, ir_mode *dest_mode)
98 mode_is_int(src_mode) &&
99 mode_is_int(dest_mode) &&
100 get_mode_size_bits(dest_mode) <= get_mode_size_bits(src_mode);
103 static int get_conv_costs(const ir_node *node, ir_mode *dest_mode)
105 ir_mode *mode = get_irn_mode(node);
110 if (mode == dest_mode)
113 if (is_Const(node)) {
114 /* TODO tarval module is incomplete and can't convert floats to ints */
115 return conv_const_tv(node, dest_mode) == tarval_bad ? 1 : 0;
119 is_downconv(mode, dest_mode) &&
120 get_irn_mode(get_Conv_op(node)) == dest_mode) {
124 if (get_irn_n_edges(node) > 1) {
125 DB((dbg, LEVEL_3, "multi outs at %+F\n", node));
129 if (ir_zero_when_converted(node, dest_mode)) {
134 /* Take the minimum of the conversion costs for Phi predecessors as only one
135 * branch is actually executed at a time */
138 int arity = get_Phi_n_preds(node);
141 costs = get_conv_costs(get_Phi_pred(node, 0), dest_mode);
142 for (i = 1; i < arity; ++i) {
143 ir_node *pred = get_Phi_pred(node, i);
144 int c = get_conv_costs(pred, dest_mode);
145 if (c < costs) costs = c;
152 if (!is_downconv(mode, dest_mode)) {
157 ir_node *pred = get_Conv_op(node);
158 ir_mode *pred_mode = get_irn_mode(pred);
160 if (!values_in_mode(dest_mode, pred_mode)) {
163 return get_conv_costs(get_Conv_op(node), dest_mode) - 1;
166 if (!is_optimizable_node(node, dest_mode)) {
171 // The shift count does not participate in the conv optimisation
172 arity = is_Shl(node) ? 1 : get_irn_arity(node);
173 for (i = 0; i < arity; ++i) {
174 ir_node *pred = get_irn_n(node, i);
175 costs += imin(get_conv_costs(pred, dest_mode), 1);
181 static ir_node *place_conv(ir_node *node, ir_mode *dest_mode)
183 ir_node *block = get_nodes_block(node);
184 ir_node *conv = new_r_Conv(block, node, dest_mode);
188 static ir_node *conv_transform(ir_node *node, ir_mode *dest_mode)
190 ir_mode *mode = get_irn_mode(node);
191 ir_graph *irg = get_irn_irg(node);
198 if (mode == dest_mode)
201 if (is_Const(node)) {
202 /* TODO tarval module is incomplete and can't convert floats to ints */
203 ir_tarval *tv = conv_const_tv(node, dest_mode);
204 if (tv == tarval_bad) {
205 return place_conv(node, dest_mode);
207 return new_r_Const(irg, tv);
212 is_downconv(mode, dest_mode) &&
213 get_irn_mode(get_Conv_op(node)) == dest_mode) {
214 return get_Conv_op(node);
217 if (get_irn_n_edges(node) > 1) {
218 return place_conv(node, dest_mode);
221 if (!is_downconv(mode, dest_mode)) {
222 return place_conv(node, dest_mode);
226 ir_node *pred = get_Conv_op(node);
227 ir_mode *pred_mode = get_irn_mode(pred);
229 if (!values_in_mode(dest_mode, pred_mode)) {
230 return place_conv(node, dest_mode);
232 return conv_transform(get_Conv_op(node), dest_mode);
235 if (!is_optimizable_node(node, dest_mode)) {
236 return place_conv(node, dest_mode);
239 // We want to create a new node with the right mode
240 arity = get_irn_arity(node);
241 ins = ALLOCAN(ir_node *, arity);
243 // The shift count does not participate in the conv optimisation
244 conv_arity = is_Shl(node) ? 1 : arity;
245 for (i = 0; i < conv_arity; i++) {
246 ir_node *pred = get_irn_n(node, i);
247 ir_node *transformed;
248 if (get_conv_costs(pred, dest_mode) > 0) {
249 transformed = place_conv(pred, dest_mode);
251 transformed = conv_transform(pred, dest_mode);
253 ins[i] = transformed;
256 for (i = conv_arity; i < arity; i++) {
257 ins[i] = get_irn_n(node, i);
260 new_node = new_ir_node(get_irn_dbg_info(node),
262 get_nodes_block(node),
267 copy_node_attr(irg, node, new_node);
272 static void conv_opt_walker(ir_node *node, void *data)
274 ir_node *transformed;
279 bool *changed = (bool*)data;
284 pred = get_Conv_op(node);
285 mode = get_irn_mode(node);
286 pred_mode = get_irn_mode(pred);
288 if (mode_is_reference(mode) || mode_is_reference(pred_mode))
291 if (!is_Phi(pred) && !is_downconv(pred_mode, mode))
294 /* - 1 for the initial conv */
295 costs = get_conv_costs(pred, mode) - 1;
296 DB((dbg, LEVEL_2, "Costs for %+F -> %+F: %d\n", node, pred, costs));
300 transformed = conv_transform(pred, mode);
301 if (node != transformed) {
304 exchange(node, transformed);
305 vrp = vrp_get_info(transformed);
306 if (vrp && vrp->valid) {
307 vrp->range_type = VRP_VARYING;
308 vrp->bits_set = tarval_convert_to(vrp->bits_set, mode);
309 vrp->bits_not_set = tarval_convert_to(vrp->bits_not_set, mode);
316 static ir_graph_state_t do_deconv(ir_graph *irg)
319 FIRM_DBG_REGISTER(dbg, "firm.opt.conv");
321 DB((dbg, LEVEL_1, "===> Performing conversion optimization on %+F\n", irg));
325 irg_walk_graph(irg, NULL, conv_opt_walker, &changed);
326 local_optimize_graph(irg);
332 static optdesc_t opt_deconv = {
334 IR_GRAPH_STATE_CONSISTENT_OUT_EDGES,
338 int conv_opt(ir_graph *irg)
340 perform_irg_optimization(irg, &opt_deconv);
344 /* Creates an ir_graph pass for conv_opt. */
345 ir_graph_pass_t *conv_opt_pass(const char *name)
347 ir_graph_pass_t *path = def_graph_pass_ret(name ? name : "conv_opt", conv_opt);
349 /* safe to run parallel on all irgs */
350 ir_graph_pass_set_parallel(path, 1);