2 * This file is part of libFirm.
3 * Copyright (C) 2012 University of Karlsruhe.
8 * @brief This file contains functions for matching firm graphs for
9 * nodes that can be used as address mode for x86 instructions
10 * @author Matthias Braun
14 #include "ia32_address_mode.h"
15 #include "ia32_transform.h"
21 #include "iredges_t.h"
29 /* gas/ld don't support negative symconsts :-( */
30 #undef SUPPORT_NEGATIVE_SYMCONSTS
32 static bitset_t *non_address_mode_nodes;
35 * Recursive worker for checking if a DAG with root node can be represented as a simple immediate,
37 * @param node the node
38 * @param symconsts number of symconsts found so far
39 * @param negate if set, the immediate must be negated
41 * @return non-zero if the DAG represents an immediate, 0 else
43 static bool do_is_immediate(const ir_node *node, int *symconsts, bool negate)
48 switch (get_irn_opcode(node)) {
50 /* Consts are typically immediates */
51 if (!tarval_is_long(get_Const_tarval(node))) {
54 "Optimisation warning tarval of %+F(%+F) is not a long.\n",
55 node, get_irn_irg(node));
61 /* the first SymConst of a DAG can be fold into an immediate */
62 #ifndef SUPPORT_NEGATIVE_SYMCONSTS
63 /* unfortunately the assembler/linker doesn't support -symconst */
67 if (get_SymConst_kind(node) != symconst_addr_ent)
74 /* we can use '0' for Unknowns */
78 /* Add's and Sub's are typically supported as long as both operands are
80 if (ia32_is_non_address_mode_node(node))
83 left = get_binop_left(node);
84 if (!do_is_immediate(left, symconsts, negate))
86 right = get_binop_right(node);
87 if (!do_is_immediate(right, symconsts, is_Sub(node) ? !negate : negate))
92 /* all other nodes are NO immediates */
98 * Check if a DAG starting with root node can be folded into an address mode
101 * @param addr the address mode data so far
102 * @param node the node
103 * @param negate if set, the immediate must be negated
105 static int is_immediate(ia32_address_t *addr, const ir_node *node, bool negate)
107 int symconsts = (addr->symconst_ent != NULL);
108 return do_is_immediate(node, &symconsts, negate);
112 * Place a DAG with root node into an address mode.
114 * @param addr the address mode data so far
115 * @param node the node
116 * @param negate if set, the immediate must be negated
118 static void eat_immediate(ia32_address_t *addr, ir_node *node, bool negate)
125 switch (get_irn_opcode(node)) {
127 /* simply add the value to the offset */
128 tv = get_Const_tarval(node);
129 val = get_tarval_long(tv);
137 /* place the entity into the symconst */
138 if (addr->symconst_ent != NULL) {
139 panic("Internal error: more than 1 symconst in address calculation");
141 addr->symconst_ent = get_SymConst_entity(node);
142 if (get_entity_owner(addr->symconst_ent) == get_tls_type())
143 addr->tls_segment = true;
144 #ifndef SUPPORT_NEGATIVE_SYMCONSTS
147 addr->symconst_sign = negate;
152 assert(!ia32_is_non_address_mode_node(node));
153 left = get_Add_left(node);
154 eat_immediate(addr, left, negate);
155 right = get_Add_right(node);
156 eat_immediate(addr, right, negate);
159 assert(!ia32_is_non_address_mode_node(node));
160 left = get_Sub_left(node);
161 eat_immediate(addr, left, negate);
162 right = get_Sub_right(node);
163 eat_immediate(addr, right, !negate);
166 panic("Internal error in immediate address calculation");
171 * Place operands of node into an address mode.
173 * @param addr the address mode data so far
174 * @param node the node
175 * @param flags the flags
177 * @return the folded node
179 static ir_node *eat_immediates(ia32_address_t *addr, ir_node *node,
180 ia32_create_am_flags_t flags)
182 if (!(flags & ia32_create_am_force) &&
183 ia32_is_non_address_mode_node(node) &&
184 (!(flags & ia32_create_am_double_use) || get_irn_n_edges(node) > 2))
188 ir_node *left = get_Add_left(node);
189 ir_node *right = get_Add_right(node);
191 if (is_immediate(addr, left, 0)) {
192 eat_immediate(addr, left, 0);
193 return eat_immediates(addr, right, ia32_create_am_normal);
195 if (is_immediate(addr, right, 0)) {
196 eat_immediate(addr, right, 0);
197 return eat_immediates(addr, left, ia32_create_am_normal);
199 } else if (is_Sub(node)) {
200 ir_node *left = get_Sub_left(node);
201 ir_node *right = get_Sub_right(node);
203 if (is_immediate(addr, right, 1)) {
204 eat_immediate(addr, right, 1);
205 return eat_immediates(addr, left, ia32_create_am_normal);
213 * Try to place a Shl into an address mode.
215 * @param addr the address mode data so far
216 * @param node the node to place
218 * @return non-zero on success
220 static int eat_shl(ia32_address_t *addr, ir_node *node)
222 ir_node *shifted_val;
226 ir_node *right = get_Shl_right(node);
229 /* we can use shl with 1, 2 or 3 shift */
230 if (!is_Const(right))
232 tv = get_Const_tarval(right);
233 if (!tarval_is_long(tv))
236 val = get_tarval_long(tv);
237 if (val < 0 || val > 3)
240 ir_fprintf(stderr, "Optimisation warning: unoptimized Shl(,0) found\n");
243 shifted_val = get_Shl_left(node);
244 } else if (is_Add(node)) {
245 /* might be an add x, x */
246 ir_node *left = get_Add_left(node);
247 ir_node *right = get_Add_right(node);
260 /* we can only eat a shl if we don't have a scale or index set yet */
261 if (addr->scale != 0 || addr->index != NULL)
263 if (ia32_is_non_address_mode_node(node))
266 #ifndef AGGRESSIVE_AM
267 if (get_irn_n_edges(node) > 1)
272 addr->index = shifted_val;
276 /* Create an address mode for a given node. */
277 void ia32_create_address_mode(ia32_address_t *addr, ir_node *node, ia32_create_am_flags_t flags)
281 if (is_immediate(addr, node, 0)) {
282 eat_immediate(addr, node, 0);
286 #ifndef AGGRESSIVE_AM
287 if (!(flags & ia32_create_am_force) && get_irn_n_edges(node) > 1) {
293 if (!(flags & ia32_create_am_force) &&
294 ia32_is_non_address_mode_node(node) &&
295 (!(flags & ia32_create_am_double_use) || get_irn_n_edges(node) > 2)) {
300 eat_imms = eat_immediates(addr, node, flags);
301 if (eat_imms != node) {
302 if (flags & ia32_create_am_force) {
303 eat_imms = ia32_skip_downconv(eat_imms);
307 #ifndef AGGRESSIVE_AM
308 if (get_irn_n_edges(node) > 1) {
313 if (ia32_is_non_address_mode_node(node)) {
319 /* starting point Add, Sub or Shl, FrameAddr */
321 /* We don't want to eat add x, x as shl here, so only test for real Shl
322 * instructions, because we want the former as Lea x, x, not Shl x, 1 */
323 if (eat_shl(addr, node))
325 } else if (is_immediate(addr, node, 0)) {
326 eat_immediate(addr, node, 0);
328 } else if (be_is_FrameAddr(node)) {
329 assert(addr->base == NULL);
330 assert(addr->frame_entity == NULL);
331 addr->base = be_get_FrameAddr_frame(node);
333 addr->frame_entity = be_get_FrameAddr_entity(node);
335 } else if (is_Add(node)) {
336 ir_node *left = get_Add_left(node);
337 ir_node *right = get_Add_right(node);
339 if (flags & ia32_create_am_force) {
340 left = ia32_skip_downconv(left);
341 right = ia32_skip_downconv(right);
344 assert(flags & ia32_create_am_force || !is_immediate(addr, left, 0));
345 assert(flags & ia32_create_am_force || !is_immediate(addr, right, 0));
347 if (eat_shl(addr, left)) {
349 } else if (eat_shl(addr, right)) {
353 be_is_FrameAddr(left) &&
354 !ia32_is_non_address_mode_node(left)) {
355 assert(addr->base == NULL);
356 assert(addr->frame_entity == NULL);
357 addr->base = be_get_FrameAddr_frame(left);
359 addr->frame_entity = be_get_FrameAddr_entity(left);
361 } else if (right != NULL &&
362 be_is_FrameAddr(right) &&
363 !ia32_is_non_address_mode_node(right)) {
364 assert(addr->base == NULL);
365 assert(addr->frame_entity == NULL);
366 addr->base = be_get_FrameAddr_frame(right);
368 addr->frame_entity = be_get_FrameAddr_entity(right);
373 if (addr->base != NULL) {
374 assert(addr->index == NULL && addr->scale == 0);
375 assert(right == NULL);
382 if (addr->base == NULL) {
385 assert(addr->index == NULL && addr->scale == 0);
395 void ia32_mark_non_am(ir_node *node)
397 bitset_set(non_address_mode_nodes, get_irn_idx(node));
400 int ia32_is_non_address_mode_node(ir_node const *node)
402 return bitset_is_set(non_address_mode_nodes, get_irn_idx(node));
406 * Check if a given value is last used (i.e. die after) the block of some
409 static int value_last_used_here(be_lv_t *lv, ir_node *here, ir_node *value)
411 ir_node *block = get_nodes_block(here);
413 /* If the value is live end it is for sure it does not die here */
414 if (be_is_live_end(lv, block, value)) return 0;
416 /* if multiple nodes in this block use the value, then we cannot decide
417 * whether the value will die here (because there is no schedule yet).
418 * Assume it does not die in this case. */
419 foreach_out_edge(value, edge) {
420 ir_node *user = get_edge_src_irn(edge);
421 if (user != here && get_nodes_block(user) == block) {
429 static bool simple_is_immediate(const ir_node *node)
432 return do_is_immediate(node, &symconsts, false);
436 * Walker: mark those nodes that cannot be part of an address mode because
437 * their value must be accessed through a register
439 static void mark_non_address_nodes(ir_node *node, void *env)
441 be_lv_t *lv = (be_lv_t*)env;
449 mode = get_irn_mode(node);
450 if (!mode_is_int(mode) && !mode_is_reference(mode) && mode != mode_b)
453 switch (get_irn_opcode(node)) {
455 /* Nothing to do. especially do not mark the pointer, because we want to
456 * turn it into AM. */
460 /* Do not mark the pointer, because we want to turn it into AM. */
461 val = get_Store_value(node);
462 ia32_mark_non_am(val);
467 /* only 1 user: AM folding is always beneficial */
468 if (get_irn_n_edges(node) <= 1)
471 /* for adds and shls with multiple users we use this heuristic:
472 * we do not fold them into address mode if their operands don't live
473 * out of the block, because in this case we will reduce register
474 * pressure. Otherwise we fold them in aggressively in the hope, that
475 * the node itself doesn't exist anymore and we were able to save the
476 * register for the result */
477 left = get_binop_left(node);
478 right = get_binop_right(node);
480 /* if any of the operands is an immediate then this will not
481 * increase register pressure */
482 if (simple_is_immediate(left) || simple_is_immediate(right))
485 /* Fold AM if any of the two operands does not die here. This duplicates
486 * an addition and has the same register pressure for the case that only
487 * one operand dies, but is faster (on Pentium 4).
488 * && instead of || only folds AM if both operands do not die here */
489 if (!value_last_used_here(lv, node, left) ||
490 !value_last_used_here(lv, node, right)) {
494 /* At least one of left and right are not used by anyone else, so it is
495 * beneficial for the register pressure (if both are unused otherwise,
496 * else neutral) and ALU use to not fold AM. */
497 ia32_mark_non_am(node);
501 arity = get_irn_arity(node);
503 for (i = 0; i < arity; ++i) {
504 ir_node *in = get_irn_n(node, i);
505 ia32_mark_non_am(in);
511 void ia32_calculate_non_address_mode_nodes(ir_graph *irg)
515 be_assure_live_chk(irg);
516 lv = be_get_irg_liveness(irg);
518 non_address_mode_nodes = bitset_malloc(get_irg_last_idx(irg));
520 irg_walk_graph(irg, NULL, mark_non_address_nodes, lv);
523 void ia32_free_non_address_mode_nodes(void)
525 bitset_free(non_address_mode_nodes);