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22 * @brief conv node optimisation
23 * @author Matthias Braun, Christoph Mallon
25 * Try to minimize the number of conv nodes by changing modes of operations.
26 * The typical example is the following structure:
31 * Add Is gets transformed to |
35 * TODO: * try to optimize cmp modes
36 * * decide when it is useful to move the convs through phis
40 #include "iroptimize.h"
50 #include "iredges_t.h"
57 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
59 static inline int imin(int a, int b) { return a < b ? a : b; }
61 static bool is_optimizable_node(const ir_node *node, ir_mode *dest_mode)
63 switch (get_irn_opcode(node)) {
75 int modulo_shift = get_mode_modulo_shift(dest_mode);
76 int old_shift = get_mode_modulo_shift(get_irn_mode(node));
77 /* bail out if modulo shift changes */
78 if (modulo_shift != old_shift)
88 static ir_tarval* conv_const_tv(const ir_node* cnst, ir_mode* dest_mode)
90 return tarval_convert_to(get_Const_tarval(cnst), dest_mode);
93 static int is_downconv(ir_mode *src_mode, ir_mode *dest_mode)
96 mode_is_int(src_mode) &&
97 mode_is_int(dest_mode) &&
98 get_mode_size_bits(dest_mode) <= get_mode_size_bits(src_mode);
101 static int get_conv_costs(const ir_node *node, ir_mode *dest_mode)
103 ir_mode *mode = get_irn_mode(node);
108 if (mode == dest_mode)
111 if (is_Const(node)) {
112 return conv_const_tv(node, dest_mode) == tarval_bad ? 1 : 0;
116 is_downconv(mode, dest_mode) &&
117 get_irn_mode(get_Conv_op(node)) == dest_mode) {
121 if (get_irn_n_edges(node) > 1) {
122 DB((dbg, LEVEL_3, "multi outs at %+F\n", node));
126 if (ir_zero_when_converted(node, dest_mode)) {
131 /* Take the minimum of the conversion costs for Phi predecessors as only one
132 * branch is actually executed at a time */
135 int arity = get_Phi_n_preds(node);
138 costs = get_conv_costs(get_Phi_pred(node, 0), dest_mode);
139 for (i = 1; i < arity; ++i) {
140 ir_node *pred = get_Phi_pred(node, i);
141 int c = get_conv_costs(pred, dest_mode);
142 if (c < costs) costs = c;
149 if (!is_downconv(mode, dest_mode)) {
154 ir_node *pred = get_Conv_op(node);
155 ir_mode *pred_mode = get_irn_mode(pred);
157 if (smaller_mode(pred_mode, dest_mode)) {
158 return get_conv_costs(get_Conv_op(node), dest_mode) - 1;
160 if (may_leave_out_middle_conv(pred_mode, mode, dest_mode)) {
167 if (!is_optimizable_node(node, dest_mode)) {
172 // The shift count does not participate in the conv optimisation
173 arity = is_Shl(node) ? 1 : get_irn_arity(node);
174 for (i = 0; i < arity; ++i) {
175 ir_node *pred = get_irn_n(node, i);
176 costs += imin(get_conv_costs(pred, dest_mode), 1);
182 static ir_node *place_conv(ir_node *node, ir_mode *dest_mode)
184 ir_node *block = get_nodes_block(node);
185 ir_node *conv = new_r_Conv(block, node, dest_mode);
189 static ir_node *conv_transform(ir_node *node, ir_mode *dest_mode)
191 ir_mode *mode = get_irn_mode(node);
192 ir_graph *irg = get_irn_irg(node);
199 if (mode == dest_mode)
202 if (is_Const(node)) {
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 (smaller_mode(pred_mode, dest_mode)) {
230 return conv_transform(get_Conv_op(node), dest_mode);
232 return place_conv(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) {
302 exchange(node, transformed);
307 void conv_opt(ir_graph *irg)
309 bool global_changed = false;
311 FIRM_DBG_REGISTER(dbg, "firm.opt.conv");
313 assure_irg_properties(irg, IR_GRAPH_PROPERTY_CONSISTENT_OUT_EDGES);
315 DB((dbg, LEVEL_1, "===> Performing conversion optimization on %+F\n", irg));
319 irg_walk_graph(irg, NULL, conv_opt_walker, &changed);
320 local_optimize_graph(irg);
321 global_changed |= changed;
324 confirm_irg_properties(irg,
325 global_changed ? IR_GRAPH_PROPERTIES_NONE : IR_GRAPH_PROPERTIES_ALL);
328 /* Creates an ir_graph pass for conv_opt. */
329 ir_graph_pass_t *conv_opt_pass(const char *name)
331 ir_graph_pass_t *path = def_graph_pass(name ? name : "conv_opt", conv_opt);
333 /* safe to run parallel on all irgs */
334 ir_graph_pass_set_parallel(path, 1);