2010-04-01 Zoltan Varga <vargaz@gmail.com>
[mono/afaerber.git] / mono / mini / local-propagation.c
blob3c76408f3e44ce31d0e4869c3e51aec8ba7549be
1 /*
2 * local-propagation.c: Local constant, copy and tree propagation.
4 * To make some sense of the tree mover, read mono/docs/tree-mover.txt
6 * Author:
7 * Paolo Molaro (lupus@ximian.com)
8 * Dietmar Maurer (dietmar@ximian.com)
9 * Massimiliano Mantione (massi@ximian.com)
11 * (C) 2006 Novell, Inc. http://www.novell.com
15 #include <string.h>
16 #include <stdio.h>
17 #ifdef HAVE_ALLOCA_H
18 #include <alloca.h>
19 #endif
21 #include <mono/metadata/debug-helpers.h>
22 #include <mono/metadata/mempool.h>
23 #include <mono/metadata/opcodes.h>
24 #include "mini.h"
25 #include "ir-emit.h"
27 #ifndef MONO_ARCH_IS_OP_MEMBASE
28 #define MONO_ARCH_IS_OP_MEMBASE(opcode) FALSE
29 #endif
31 static inline MonoBitSet*
32 mono_bitset_mp_new_noinit (MonoMemPool *mp, guint32 max_size)
34 int size = mono_bitset_alloc_size (max_size, 0);
35 gpointer mem;
37 mem = mono_mempool_alloc (mp, size);
38 return mono_bitset_mem_new (mem, max_size, MONO_BITSET_DONT_FREE);
42 * mono_local_cprop:
44 * A combined local copy and constant propagation pass.
46 void
47 mono_local_cprop (MonoCompile *cfg)
49 MonoBasicBlock *bb;
50 MonoInst **defs;
51 gint32 *def_index;
52 int max;
54 restart:
56 max = cfg->next_vreg;
57 defs = mono_mempool_alloc (cfg->mempool, sizeof (MonoInst*) * (cfg->next_vreg + 1));
58 def_index = mono_mempool_alloc (cfg->mempool, sizeof (guint32) * (cfg->next_vreg + 1));
60 for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
61 MonoInst *ins;
62 int ins_index;
63 int last_call_index;
65 /* Manually init the defs entries used by the bblock */
66 MONO_BB_FOR_EACH_INS (bb, ins) {
67 int sregs [MONO_MAX_SRC_REGS];
68 int num_sregs, i;
70 if ((ins->dreg != -1) && (ins->dreg < max)) {
71 defs [ins->dreg] = NULL;
72 #if SIZEOF_REGISTER == 4
73 defs [ins->dreg + 1] = NULL;
74 #endif
77 num_sregs = mono_inst_get_src_registers (ins, sregs);
78 for (i = 0; i < num_sregs; ++i) {
79 int sreg = sregs [i];
80 if (sreg < max) {
81 defs [sreg] = NULL;
82 #if SIZEOF_REGISTER == 4
83 defs [sreg + 1] = NULL;
84 #endif
89 ins_index = 0;
90 last_call_index = -1;
91 MONO_BB_FOR_EACH_INS (bb, ins) {
92 const char *spec = INS_INFO (ins->opcode);
93 int regtype, srcindex, sreg;
94 int num_sregs;
95 int sregs [MONO_MAX_SRC_REGS];
97 if (ins->opcode == OP_NOP) {
98 MONO_DELETE_INS (bb, ins);
99 continue;
102 g_assert (ins->opcode > MONO_CEE_LAST);
104 /* FIXME: Optimize this */
105 if (ins->opcode == OP_LDADDR) {
106 MonoInst *var = ins->inst_p0;
108 defs [var->dreg] = NULL;
110 if (!MONO_TYPE_ISSTRUCT (var->inst_vtype))
111 break;
115 if (MONO_IS_STORE_MEMBASE (ins)) {
116 sreg = ins->dreg;
117 regtype = 'i';
119 if ((regtype == 'i') && (sreg != -1) && defs [sreg]) {
120 MonoInst *def = defs [sreg];
122 if ((def->opcode == OP_MOVE) && (!defs [def->sreg1] || (def_index [def->sreg1] < def_index [sreg])) && !vreg_is_volatile (cfg, def->sreg1)) {
123 int vreg = def->sreg1;
124 if (cfg->verbose_level > 2) printf ("CCOPY: R%d -> R%d\n", sreg, vreg);
125 ins->dreg = vreg;
130 num_sregs = mono_inst_get_src_registers (ins, sregs);
131 for (srcindex = 0; srcindex < num_sregs; ++srcindex) {
132 MonoInst *def;
133 int nsregs;
135 nsregs = mono_inst_get_src_registers (ins, sregs);
137 regtype = spec [MONO_INST_SRC1 + srcindex];
138 sreg = sregs [srcindex];
140 if ((regtype == ' ') || (sreg == -1) || (!defs [sreg]))
141 continue;
143 def = defs [sreg];
145 /* Copy propagation */
147 * The first check makes sure the source of the copy did not change since
148 * the copy was made.
149 * The second check avoids volatile variables.
150 * The third check avoids copy propagating local vregs through a call,
151 * since the lvreg will be spilled
152 * The fourth check avoids copy propagating a vreg in cases where
153 * it would be eliminated anyway by reverse copy propagation later,
154 * because propagating it would create another use for it, thus making
155 * it impossible to use reverse copy propagation.
157 /* Enabling this for floats trips up the fp stack */
159 * Enabling this for floats on amd64 seems to cause a failure in
160 * basic-math.cs, most likely because it gets rid of some r8->r4
161 * conversions.
163 if (MONO_IS_MOVE (def) &&
164 (!defs [def->sreg1] || (def_index [def->sreg1] < def_index [sreg])) &&
165 !vreg_is_volatile (cfg, def->sreg1) &&
166 /* This avoids propagating local vregs across calls */
167 ((get_vreg_to_inst (cfg, def->sreg1) || !defs [def->sreg1] || (def_index [def->sreg1] >= last_call_index) || (def->opcode == OP_VMOVE))) &&
168 !(defs [def->sreg1] && defs [def->sreg1]->next == def) &&
169 (!MONO_ARCH_USE_FPSTACK || (def->opcode != OP_FMOVE)) &&
170 (def->opcode != OP_FMOVE)) {
171 int vreg = def->sreg1;
173 if (cfg->verbose_level > 2) printf ("CCOPY/2: R%d -> R%d\n", sreg, vreg);
174 sregs [srcindex] = vreg;
175 mono_inst_set_src_registers (ins, sregs);
177 /* Allow further iterations */
178 srcindex = -1;
179 continue;
182 /* Constant propagation */
183 /* FIXME: Make is_inst_imm a macro */
184 /* FIXME: Make is_inst_imm take an opcode argument */
185 /* is_inst_imm is only needed for binops */
186 if ((((def->opcode == OP_ICONST) || ((sizeof (gpointer) == 8) && (def->opcode == OP_I8CONST))) &&
187 (((srcindex == 0) && (ins->sreg2 == -1)) || mono_arch_is_inst_imm (def->inst_c0))) ||
188 (!MONO_ARCH_USE_FPSTACK && (def->opcode == OP_R8CONST))) {
189 guint32 opcode2;
191 /* srcindex == 1 -> binop, ins->sreg2 == -1 -> unop */
192 if ((srcindex == 1) && (ins->sreg1 != -1) && defs [ins->sreg1] && (defs [ins->sreg1]->opcode == OP_ICONST) && defs [ins->sreg2]) {
193 /* Both arguments are constants, perform cfold */
194 mono_constant_fold_ins (cfg, ins, defs [ins->sreg1], defs [ins->sreg2], TRUE);
195 } else if ((srcindex == 0) && (ins->sreg2 != -1) && defs [ins->sreg2]) {
196 /* Arg 1 is constant, swap arguments if possible */
197 int opcode = ins->opcode;
198 mono_constant_fold_ins (cfg, ins, defs [ins->sreg1], defs [ins->sreg2], TRUE);
199 if (ins->opcode != opcode) {
200 /* Allow further iterations */
201 srcindex = -1;
202 continue;
204 } else if ((srcindex == 0) && (ins->sreg2 == -1)) {
205 /* Constant unop, perform cfold */
206 mono_constant_fold_ins (cfg, ins, defs [ins->sreg1], NULL, TRUE);
209 opcode2 = mono_op_to_op_imm (ins->opcode);
210 if ((opcode2 != -1) && mono_arch_is_inst_imm (def->inst_c0) && ((srcindex == 1) || (ins->sreg2 == -1))) {
211 ins->opcode = opcode2;
212 if ((def->opcode == OP_I8CONST) && (sizeof (gpointer) == 4)) {
213 ins->inst_ls_word = def->inst_ls_word;
214 ins->inst_ms_word = def->inst_ms_word;
215 } else {
216 ins->inst_imm = def->inst_c0;
218 sregs [srcindex] = -1;
219 mono_inst_set_src_registers (ins, sregs);
221 if ((opcode2 == OP_VOIDCALL) || (opcode2 == OP_CALL) || (opcode2 == OP_LCALL) || (opcode2 == OP_FCALL))
222 ((MonoCallInst*)ins)->fptr = (gpointer)ins->inst_imm;
224 /* Allow further iterations */
225 srcindex = -1;
226 continue;
228 else {
229 /* Special cases */
230 #if defined(TARGET_X86) || defined(TARGET_AMD64)
231 if ((ins->opcode == OP_X86_LEA) && (srcindex == 1)) {
232 #if SIZEOF_REGISTER == 8
233 /* FIXME: Use OP_PADD_IMM when the new JIT is done */
234 ins->opcode = OP_LADD_IMM;
235 #else
236 ins->opcode = OP_ADD_IMM;
237 #endif
238 ins->inst_imm += def->inst_c0 << ins->backend.shift_amount;
239 ins->sreg2 = -1;
241 #endif
242 opcode2 = mono_load_membase_to_load_mem (ins->opcode);
243 if ((srcindex == 0) && (opcode2 != -1) && mono_arch_is_inst_imm (def->inst_c0)) {
244 ins->opcode = opcode2;
245 ins->inst_imm = def->inst_c0 + ins->inst_offset;
246 ins->sreg1 = -1;
250 else if (((def->opcode == OP_ADD_IMM) || (def->opcode == OP_LADD_IMM)) && (MONO_IS_LOAD_MEMBASE (ins) || MONO_ARCH_IS_OP_MEMBASE (ins->opcode))) {
251 /* ADD_IMM is created by spill_global_vars */
253 * We have to guarantee that def->sreg1 haven't changed since def->dreg
254 * was defined. cfg->frame_reg is assumed to remain constant.
256 if ((def->sreg1 == cfg->frame_reg) || ((def->next == ins) && (def->dreg != def->sreg1))) {
257 ins->inst_basereg = def->sreg1;
258 ins->inst_offset += def->inst_imm;
260 } else if ((ins->opcode == OP_ISUB_IMM) && (def->opcode == OP_IADD_IMM) && (def->next == ins) && (def->dreg != def->sreg1)) {
261 ins->sreg1 = def->sreg1;
262 ins->inst_imm -= def->inst_imm;
263 } else if ((ins->opcode == OP_IADD_IMM) && (def->opcode == OP_ISUB_IMM) && (def->next == ins) && (def->dreg != def->sreg1)) {
264 ins->sreg1 = def->sreg1;
265 ins->inst_imm -= def->inst_imm;
266 } else if (ins->opcode == OP_STOREI1_MEMBASE_REG &&
267 (def->opcode == OP_ICONV_TO_U1 || def->opcode == OP_ICONV_TO_I1 || def->opcode == OP_SEXT_I4 || (SIZEOF_REGISTER == 8 && def->opcode == OP_LCONV_TO_U1)) &&
268 (!defs [def->sreg1] || (def_index [def->sreg1] < def_index [sreg]))) {
269 /* Avoid needless sign extension */
270 ins->sreg1 = def->sreg1;
271 } else if (ins->opcode == OP_STOREI2_MEMBASE_REG &&
272 (def->opcode == OP_ICONV_TO_U2 || def->opcode == OP_ICONV_TO_I2 || def->opcode == OP_SEXT_I4 || (SIZEOF_REGISTER == 8 && def->opcode == OP_LCONV_TO_I2)) &&
273 (!defs [def->sreg1] || (def_index [def->sreg1] < def_index [sreg]))) {
274 /* Avoid needless sign extension */
275 ins->sreg1 = def->sreg1;
279 /* Do strength reduction here */
280 /* FIXME: Add long/float */
281 switch (ins->opcode) {
282 case OP_MOVE:
283 case OP_XMOVE:
284 if (ins->dreg == ins->sreg1) {
285 MONO_DELETE_INS (bb, ins);
286 spec = INS_INFO (ins->opcode);
288 break;
289 case OP_ADD_IMM:
290 case OP_IADD_IMM:
291 case OP_SUB_IMM:
292 case OP_ISUB_IMM:
293 #if SIZEOF_REGISTER == 8
294 case OP_LADD_IMM:
295 case OP_LSUB_IMM:
296 #endif
297 if (ins->inst_imm == 0) {
298 ins->opcode = OP_MOVE;
299 spec = INS_INFO (ins->opcode);
301 break;
302 case OP_MUL_IMM:
303 case OP_IMUL_IMM:
304 #if SIZEOF_REGISTER == 8
305 case OP_LMUL_IMM:
306 #endif
307 if (ins->inst_imm == 0) {
308 ins->opcode = (ins->opcode == OP_LMUL_IMM) ? OP_I8CONST : OP_ICONST;
309 ins->inst_c0 = 0;
310 ins->sreg1 = -1;
311 } else if (ins->inst_imm == 1) {
312 ins->opcode = OP_MOVE;
313 } else if ((ins->opcode == OP_IMUL_IMM) && (ins->inst_imm == -1)) {
314 ins->opcode = OP_INEG;
315 } else if ((ins->opcode == OP_LMUL_IMM) && (ins->inst_imm == -1)) {
316 ins->opcode = OP_LNEG;
317 } else {
318 int power2 = mono_is_power_of_two (ins->inst_imm);
319 if (power2 >= 0) {
320 ins->opcode = (ins->opcode == OP_MUL_IMM) ? OP_SHL_IMM : ((ins->opcode == OP_LMUL_IMM) ? OP_LSHL_IMM : OP_ISHL_IMM);
321 ins->inst_imm = power2;
324 spec = INS_INFO (ins->opcode);
325 break;
326 case OP_IREM_UN_IMM:
327 case OP_IDIV_UN_IMM: {
328 int c = ins->inst_imm;
329 int power2 = mono_is_power_of_two (c);
331 if (power2 >= 0) {
332 if (ins->opcode == OP_IREM_UN_IMM) {
333 ins->opcode = OP_IAND_IMM;
334 ins->sreg2 = -1;
335 ins->inst_imm = (1 << power2) - 1;
336 } else if (ins->opcode == OP_IDIV_UN_IMM) {
337 ins->opcode = OP_ISHR_UN_IMM;
338 ins->sreg2 = -1;
339 ins->inst_imm = power2;
342 spec = INS_INFO (ins->opcode);
343 break;
345 case OP_IDIV_IMM: {
346 int c = ins->inst_imm;
347 int power2 = mono_is_power_of_two (c);
348 MonoInst *tmp1, *tmp2, *tmp3, *tmp4;
350 /* FIXME: Move this elsewhere cause its hard to implement it here */
351 if (power2 == 1) {
352 int r1 = mono_alloc_ireg (cfg);
354 NEW_BIALU_IMM (cfg, tmp1, OP_ISHR_UN_IMM, r1, ins->sreg1, 31);
355 mono_bblock_insert_after_ins (bb, ins, tmp1);
356 NEW_BIALU (cfg, tmp2, OP_IADD, r1, r1, ins->sreg1);
357 mono_bblock_insert_after_ins (bb, tmp1, tmp2);
358 NEW_BIALU_IMM (cfg, tmp3, OP_ISHR_IMM, ins->dreg, r1, 1);
359 mono_bblock_insert_after_ins (bb, tmp2, tmp3);
361 NULLIFY_INS (ins);
363 // We allocated a new vreg, so need to restart
364 goto restart;
365 } else if (power2 > 0) {
366 int r1 = mono_alloc_ireg (cfg);
368 NEW_BIALU_IMM (cfg, tmp1, OP_ISHR_IMM, r1, ins->sreg1, 31);
369 mono_bblock_insert_after_ins (bb, ins, tmp1);
370 NEW_BIALU_IMM (cfg, tmp2, OP_ISHR_UN_IMM, r1, r1, (32 - power2));
371 mono_bblock_insert_after_ins (bb, tmp1, tmp2);
372 NEW_BIALU (cfg, tmp3, OP_IADD, r1, r1, ins->sreg1);
373 mono_bblock_insert_after_ins (bb, tmp2, tmp3);
374 NEW_BIALU_IMM (cfg, tmp4, OP_ISHR_IMM, ins->dreg, r1, power2);
375 mono_bblock_insert_after_ins (bb, tmp3, tmp4);
377 NULLIFY_INS (ins);
379 // We allocated a new vreg, so need to restart
380 goto restart;
382 break;
386 if (spec [MONO_INST_DEST] != ' ') {
387 MonoInst *def = defs [ins->dreg];
389 if (def && (def->opcode == OP_ADD_IMM) && (def->sreg1 == cfg->frame_reg) && (MONO_IS_STORE_MEMBASE (ins))) {
390 /* ADD_IMM is created by spill_global_vars */
391 /* cfg->frame_reg is assumed to remain constant */
392 ins->inst_destbasereg = def->sreg1;
393 ins->inst_offset += def->inst_imm;
397 if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins) && !vreg_is_volatile (cfg, ins->dreg)) {
398 defs [ins->dreg] = ins;
399 def_index [ins->dreg] = ins_index;
402 if (MONO_IS_CALL (ins))
403 last_call_index = ins_index;
405 ins_index ++;
410 static inline gboolean
411 reg_is_softreg_no_fpstack (int reg, const char spec)
413 return (spec == 'i' && reg >= MONO_MAX_IREGS)
414 || ((spec == 'f' && reg >= MONO_MAX_FREGS) && !MONO_ARCH_USE_FPSTACK)
415 #ifdef MONO_ARCH_SIMD_INTRINSICS
416 || (spec == 'x' && reg >= MONO_MAX_XREGS)
417 #endif
418 || (spec == 'v');
421 static inline gboolean
422 reg_is_softreg (int reg, const char spec)
424 return (spec == 'i' && reg >= MONO_MAX_IREGS)
425 || (spec == 'f' && reg >= MONO_MAX_FREGS)
426 #ifdef MONO_ARCH_SIMD_INTRINSICS
427 || (spec == 'x' && reg >= MONO_MAX_XREGS)
428 #endif
429 || (spec == 'v');
433 * mono_local_deadce:
435 * Get rid of the dead assignments to local vregs like the ones created by the
436 * copyprop pass.
438 void
439 mono_local_deadce (MonoCompile *cfg)
441 MonoBasicBlock *bb;
442 MonoInst *ins, *prev;
443 MonoBitSet *used, *defined;
445 //mono_print_code (cfg, "BEFORE LOCAL-DEADCE");
448 * Assignments to global vregs can't be eliminated so this pass must come
449 * after the handle_global_vregs () pass.
452 used = mono_bitset_mp_new_noinit (cfg->mempool, cfg->next_vreg + 1);
453 defined = mono_bitset_mp_new_noinit (cfg->mempool, cfg->next_vreg + 1);
455 /* First pass: collect liveness info */
456 for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
457 /* Manually init the defs entries used by the bblock */
458 MONO_BB_FOR_EACH_INS (bb, ins) {
459 const char *spec = INS_INFO (ins->opcode);
460 int sregs [MONO_MAX_SRC_REGS];
461 int num_sregs, i;
463 if (spec [MONO_INST_DEST] != ' ') {
464 mono_bitset_clear_fast (used, ins->dreg);
465 mono_bitset_clear_fast (defined, ins->dreg);
466 #if SIZEOF_REGISTER == 4
467 /* Regpairs */
468 mono_bitset_clear_fast (used, ins->dreg + 1);
469 mono_bitset_clear_fast (defined, ins->dreg + 1);
470 #endif
472 num_sregs = mono_inst_get_src_registers (ins, sregs);
473 for (i = 0; i < num_sregs; ++i) {
474 mono_bitset_clear_fast (used, sregs [i]);
475 #if SIZEOF_REGISTER == 4
476 mono_bitset_clear_fast (used, sregs [i] + 1);
477 #endif
482 * Make a reverse pass over the instruction list
484 MONO_BB_FOR_EACH_INS_REVERSE_SAFE (bb, prev, ins) {
485 const char *spec = INS_INFO (ins->opcode);
486 int sregs [MONO_MAX_SRC_REGS];
487 int num_sregs, i;
489 if (ins->opcode == OP_NOP) {
490 MONO_DELETE_INS (bb, ins);
491 continue;
494 g_assert (ins->opcode > MONO_CEE_LAST);
496 if (MONO_IS_NON_FP_MOVE (ins) && ins->prev) {
497 MonoInst *def;
498 const char *spec2;
500 def = ins->prev;
501 while (def->prev && (def->opcode == OP_NOP))
502 def = def->prev;
503 spec2 = INS_INFO (def->opcode);
506 * Perform a limited kind of reverse copy propagation, i.e.
507 * transform B <- FOO; A <- B into A <- FOO
508 * This isn't copyprop, not deadce, but it can only be performed
509 * after handle_global_vregs () has run.
511 if (!get_vreg_to_inst (cfg, ins->sreg1) && (spec2 [MONO_INST_DEST] != ' ') && (def->dreg == ins->sreg1) && !mono_bitset_test_fast (used, ins->sreg1) && !MONO_IS_STORE_MEMBASE (def) && reg_is_softreg (ins->sreg1, spec [MONO_INST_DEST])) {
512 if (cfg->verbose_level > 2) {
513 printf ("\tReverse copyprop in BB%d on ", bb->block_num);
514 mono_print_ins (ins);
517 def->dreg = ins->dreg;
518 MONO_DELETE_INS (bb, ins);
519 spec = INS_INFO (ins->opcode);
523 /* Enabling this on x86 could screw up the fp stack */
524 if (reg_is_softreg_no_fpstack (ins->dreg, spec [MONO_INST_DEST])) {
526 * Assignments to global vregs can only be eliminated if there is another
527 * assignment to the same vreg later in the same bblock.
529 if (!mono_bitset_test_fast (used, ins->dreg) &&
530 (!get_vreg_to_inst (cfg, ins->dreg) || (!bb->extended && !vreg_is_volatile (cfg, ins->dreg) && mono_bitset_test_fast (defined, ins->dreg))) &&
531 MONO_INS_HAS_NO_SIDE_EFFECT (ins)) {
532 /* Happens with CMOV instructions */
533 if (ins->prev && ins->prev->opcode == OP_ICOMPARE_IMM) {
534 MonoInst *prev = ins->prev;
536 * Can't use DELETE_INS since that would interfere with the
537 * FOR_EACH_INS loop.
539 NULLIFY_INS (prev);
541 //printf ("DEADCE: "); mono_print_ins (ins);
542 MONO_DELETE_INS (bb, ins);
543 spec = INS_INFO (ins->opcode);
546 if (spec [MONO_INST_DEST] != ' ')
547 mono_bitset_clear_fast (used, ins->dreg);
550 if (spec [MONO_INST_DEST] != ' ')
551 mono_bitset_set_fast (defined, ins->dreg);
552 num_sregs = mono_inst_get_src_registers (ins, sregs);
553 for (i = 0; i < num_sregs; ++i)
554 mono_bitset_set_fast (used, sregs [i]);
555 if (MONO_IS_STORE_MEMBASE (ins))
556 mono_bitset_set_fast (used, ins->dreg);
558 if (MONO_IS_CALL (ins)) {
559 MonoCallInst *call = (MonoCallInst*)ins;
560 GSList *l;
562 if (call->out_ireg_args) {
563 for (l = call->out_ireg_args; l; l = l->next) {
564 guint32 regpair, reg;
566 regpair = (guint32)(gssize)(l->data);
567 reg = regpair & 0xffffff;
569 mono_bitset_set_fast (used, reg);
573 if (call->out_freg_args) {
574 for (l = call->out_freg_args; l; l = l->next) {
575 guint32 regpair, reg;
577 regpair = (guint32)(gssize)(l->data);
578 reg = regpair & 0xffffff;
580 mono_bitset_set_fast (used, reg);
587 //mono_print_code (cfg, "AFTER LOCAL-DEADCE");