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15 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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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 /* TODO tarval module is incomplete and can't convert floats to ints */
113 return conv_const_tv(node, dest_mode) == tarval_bad ? 1 : 0;
117 is_downconv(mode, dest_mode) &&
118 get_irn_mode(get_Conv_op(node)) == dest_mode) {
122 if (get_irn_n_edges(node) > 1) {
123 DB((dbg, LEVEL_3, "multi outs at %+F\n", node));
127 if (ir_zero_when_converted(node, dest_mode)) {
132 /* Take the minimum of the conversion costs for Phi predecessors as only one
133 * branch is actually executed at a time */
136 int arity = get_Phi_n_preds(node);
139 costs = get_conv_costs(get_Phi_pred(node, 0), dest_mode);
140 for (i = 1; i < arity; ++i) {
141 ir_node *pred = get_Phi_pred(node, i);
142 int c = get_conv_costs(pred, dest_mode);
143 if (c < costs) costs = c;
150 if (!is_downconv(mode, dest_mode)) {
155 ir_node *pred = get_Conv_op(node);
156 ir_mode *pred_mode = get_irn_mode(pred);
158 if (!values_in_mode(dest_mode, pred_mode)) {
161 return get_conv_costs(get_Conv_op(node), dest_mode) - 1;
164 if (!is_optimizable_node(node, dest_mode)) {
169 // The shift count does not participate in the conv optimisation
170 arity = is_Shl(node) ? 1 : get_irn_arity(node);
171 for (i = 0; i < arity; ++i) {
172 ir_node *pred = get_irn_n(node, i);
173 costs += imin(get_conv_costs(pred, dest_mode), 1);
179 static ir_node *place_conv(ir_node *node, ir_mode *dest_mode)
181 ir_node *block = get_nodes_block(node);
182 ir_node *conv = new_r_Conv(block, node, dest_mode);
186 static ir_node *conv_transform(ir_node *node, ir_mode *dest_mode)
188 ir_mode *mode = get_irn_mode(node);
189 ir_graph *irg = get_irn_irg(node);
196 if (mode == dest_mode)
199 if (is_Const(node)) {
200 /* TODO tarval module is incomplete and can't convert floats to ints */
201 ir_tarval *tv = conv_const_tv(node, dest_mode);
202 if (tv == tarval_bad) {
203 return place_conv(node, dest_mode);
205 return new_r_Const(irg, tv);
210 is_downconv(mode, dest_mode) &&
211 get_irn_mode(get_Conv_op(node)) == dest_mode) {
212 return get_Conv_op(node);
215 if (get_irn_n_edges(node) > 1) {
216 return place_conv(node, dest_mode);
219 if (!is_downconv(mode, dest_mode)) {
220 return place_conv(node, dest_mode);
224 ir_node *pred = get_Conv_op(node);
225 ir_mode *pred_mode = get_irn_mode(pred);
227 if (!values_in_mode(dest_mode, pred_mode)) {
228 return place_conv(node, dest_mode);
230 return conv_transform(get_Conv_op(node), dest_mode);
233 if (!is_optimizable_node(node, dest_mode)) {
234 return place_conv(node, dest_mode);
237 // We want to create a new node with the right mode
238 arity = get_irn_arity(node);
239 ins = ALLOCAN(ir_node *, arity);
241 // The shift count does not participate in the conv optimisation
242 conv_arity = is_Shl(node) ? 1 : arity;
243 for (i = 0; i < conv_arity; i++) {
244 ir_node *pred = get_irn_n(node, i);
245 ir_node *transformed;
246 if (get_conv_costs(pred, dest_mode) > 0) {
247 transformed = place_conv(pred, dest_mode);
249 transformed = conv_transform(pred, dest_mode);
251 ins[i] = transformed;
254 for (i = conv_arity; i < arity; i++) {
255 ins[i] = get_irn_n(node, i);
258 new_node = new_ir_node(get_irn_dbg_info(node),
260 get_nodes_block(node),
265 copy_node_attr(irg, node, new_node);
270 static void conv_opt_walker(ir_node *node, void *data)
272 ir_node *transformed;
277 bool *changed = (bool*)data;
282 pred = get_Conv_op(node);
283 mode = get_irn_mode(node);
284 pred_mode = get_irn_mode(pred);
286 if (mode_is_reference(mode) || mode_is_reference(pred_mode))
289 if (!is_Phi(pred) && !is_downconv(pred_mode, mode))
292 /* - 1 for the initial conv */
293 costs = get_conv_costs(pred, mode) - 1;
294 DB((dbg, LEVEL_2, "Costs for %+F -> %+F: %d\n", node, pred, costs));
298 transformed = conv_transform(pred, mode);
299 if (node != transformed) {
300 exchange(node, transformed);
305 void conv_opt(ir_graph *irg)
307 bool global_changed = false;
309 FIRM_DBG_REGISTER(dbg, "firm.opt.conv");
311 assure_irg_properties(irg, IR_GRAPH_PROPERTY_CONSISTENT_OUT_EDGES);
313 DB((dbg, LEVEL_1, "===> Performing conversion optimization on %+F\n", irg));
317 irg_walk_graph(irg, NULL, conv_opt_walker, &changed);
318 local_optimize_graph(irg);
319 global_changed |= changed;
322 confirm_irg_properties(irg,
323 global_changed ? IR_GRAPH_PROPERTIES_NONE : IR_GRAPH_PROPERTIES_ALL);
326 /* Creates an ir_graph pass for conv_opt. */
327 ir_graph_pass_t *conv_opt_pass(const char *name)
329 ir_graph_pass_t *path = def_graph_pass(name ? name : "conv_opt", conv_opt);
331 /* safe to run parallel on all irgs */
332 ir_graph_pass_set_parallel(path, 1);