2 * Simplify - do instruction simplification before CSE
4 * Copyright (C) 2004 Linus Torvalds
10 #include "expression.h"
11 #include "linearize.h"
14 /* Find the trivial parent for a phi-source */
15 static struct basic_block
*phi_parent(struct basic_block
*source
, pseudo_t pseudo
)
17 /* Can't go upwards if the pseudo is defined in the bb it came from.. */
18 if (pseudo
->type
== PSEUDO_REG
) {
19 struct instruction
*def
= pseudo
->def
;
20 if (def
->bb
== source
)
23 if (bb_list_size(source
->children
) != 1 || bb_list_size(source
->parents
) != 1)
25 return first_basic_block(source
->parents
);
28 static void clear_phi(struct instruction
*insn
)
33 FOR_EACH_PTR(insn
->phi_list
, phi
) {
34 *THIS_ADDRESS(phi
) = VOID
;
35 } END_FOR_EACH_PTR(phi
);
38 static int if_convert_phi(struct instruction
*insn
)
41 struct basic_block
*parents
[3];
42 struct basic_block
*bb
, *bb1
, *bb2
, *source
;
43 struct instruction
*br
;
47 if (linearize_ptr_list((struct ptr_list
*)insn
->phi_list
, (void **)array
, 3) != 2)
49 if (linearize_ptr_list((struct ptr_list
*)bb
->parents
, (void **)parents
, 3) != 2)
51 p1
= array
[0]->def
->src1
;
52 bb1
= array
[0]->def
->bb
;
53 p2
= array
[1]->def
->src1
;
54 bb2
= array
[1]->def
->bb
;
56 /* Only try the simple "direct parents" case */
57 if ((bb1
!= parents
[0] || bb2
!= parents
[1]) &&
58 (bb1
!= parents
[1] || bb2
!= parents
[0]))
62 * See if we can find a common source for this..
64 source
= phi_parent(bb1
, p1
);
65 if (source
!= phi_parent(bb2
, p2
))
69 * Cool. We now know that 'source' is the exclusive
70 * parent of both phi-nodes, so the exit at the
71 * end of it fully determines which one it is, and
72 * we can turn it into a select.
74 * HOWEVER, right now we only handle regular
75 * conditional branches. No multijumps or computed
76 * stuff. Verify that here.
78 br
= last_instruction(source
->insns
);
79 if (!br
|| br
->opcode
!= OP_BR
)
86 * We're in business. Match up true/false with p1/p2.
88 if (br
->bb_true
== bb2
|| br
->bb_false
== bb1
) {
95 * Ok, we can now replace that last
102 * select pseudo, p1, p2
105 * and remove the phi-node. If it then
106 * turns out that 'a' or 'b' is entirely
107 * empty (common case), and now no longer
108 * a phi-source, we'll be able to simplify
109 * the conditional branch too.
111 insert_select(source
, br
, insn
, p1
, p2
);
116 static int clean_up_phi(struct instruction
*insn
)
119 struct instruction
*last
;
124 FOR_EACH_PTR(insn
->phi_list
, phi
) {
125 struct instruction
*def
;
129 if (def
->src1
== VOID
|| !def
->bb
)
132 if (last
->src1
!= def
->src1
)
137 } END_FOR_EACH_PTR(phi
);
140 pseudo_t pseudo
= last
? last
->src1
: VOID
;
141 convert_instruction_target(insn
, pseudo
);
146 return if_convert_phi(insn
);
149 static inline void remove_usage(pseudo_t p
, pseudo_t
*usep
)
151 if (has_use_list(p
)) {
152 delete_ptr_list_entry((struct ptr_list
**)&p
->users
, usep
, 1);
154 kill_instruction(p
->def
);
158 void kill_use(pseudo_t
*usep
)
163 remove_usage(p
, usep
);
167 void kill_instruction(struct instruction
*insn
)
169 if (!insn
|| !insn
->bb
)
172 switch (insn
->opcode
) {
173 case OP_BINARY
... OP_BINCMP_END
:
175 kill_use(&insn
->src1
);
176 kill_use(&insn
->src2
);
177 repeat_phase
|= REPEAT_CSE
;
180 case OP_NOT
: case OP_NEG
:
182 kill_use(&insn
->src1
);
183 repeat_phase
|= REPEAT_CSE
;
188 repeat_phase
|= REPEAT_CSE
;
193 repeat_phase
|= REPEAT_CSE
;
195 repeat_phase
|= REPEAT_SYMBOL_CLEANUP
;
201 * Kill trivially dead instructions
203 static int dead_insn(struct instruction
*insn
, pseudo_t
*src1
, pseudo_t
*src2
, pseudo_t
*src3
)
206 FOR_EACH_PTR(insn
->target
->users
, usep
) {
209 } END_FOR_EACH_PTR(usep
);
218 static inline int constant(pseudo_t pseudo
)
220 return pseudo
->type
== PSEUDO_VAL
;
223 static int replace_with_pseudo(struct instruction
*insn
, pseudo_t pseudo
)
225 convert_instruction_target(insn
, pseudo
);
230 static int simplify_constant_rightside(struct instruction
*insn
)
232 long long value
= insn
->src2
->value
;
234 switch (insn
->opcode
) {
237 insn
->opcode
= OP_ADD
;
238 insn
->src2
= value_pseudo(-value
);
243 case OP_OR
: case OP_XOR
:
244 case OP_SHL
: case OP_SHR
:
246 return replace_with_pseudo(insn
, insn
->src1
);
249 case OP_AND
: case OP_MUL
:
251 return replace_with_pseudo(insn
, insn
->src2
);
257 static int simplify_constant_leftside(struct instruction
*insn
)
259 long long value
= insn
->src1
->value
;
261 switch (insn
->opcode
) {
262 case OP_ADD
: case OP_OR
: case OP_XOR
:
264 return replace_with_pseudo(insn
, insn
->src2
);
267 case OP_SHL
: case OP_SHR
:
268 case OP_AND
: case OP_MUL
:
270 return replace_with_pseudo(insn
, insn
->src1
);
276 static int simplify_constant_binop(struct instruction
*insn
)
278 /* FIXME! Verify signs and sizes!! */
279 long long left
= insn
->src1
->value
;
280 long long right
= insn
->src2
->value
;
283 switch (insn
->opcode
) {
291 /* FIXME! Check sign! */
297 /* FIXME! Check sign! */
303 /* FIXME! Check sign! */
310 /* FIXME! Check sign! */
330 /* Binary comparison */
338 /* FIXME! Check sign! */
342 /* FIXME! Check sign! */
346 /* FIXME! Check sign! */
350 /* FIXME! Check sign! */
354 /* FIXME! Check sign! */
355 res
= (unsigned long long) left
< (unsigned long long) right
;
358 /* FIXME! Check sign! */
359 res
= (unsigned long long) left
> (unsigned long long) right
;
362 /* FIXME! Check sign! */
363 res
= (unsigned long long) left
<= (unsigned long long) right
;
366 /* FIXME! Check sign! */
367 res
= (unsigned long long) left
>= (unsigned long long) right
;
372 mask
= 1ULL << (insn
->size
-1);
373 res
&= mask
| (mask
-1);
375 /* FIXME!! Sign??? */
376 replace_with_pseudo(insn
, value_pseudo(res
));
380 static int simplify_binop(struct instruction
*insn
)
382 if (dead_insn(insn
, &insn
->src1
, &insn
->src2
, NULL
))
384 if (constant(insn
->src1
)) {
385 if (constant(insn
->src2
))
386 return simplify_constant_binop(insn
);
387 return simplify_constant_leftside(insn
);
389 if (constant(insn
->src2
))
390 return simplify_constant_rightside(insn
);
394 static int simplify_constant_unop(struct instruction
*insn
)
396 long long val
= insn
->src1
->value
;
399 switch (insn
->opcode
) {
409 mask
= 1ULL << (insn
->size
-1);
410 res
&= mask
| (mask
-1);
412 replace_with_pseudo(insn
, value_pseudo(res
));
416 static int simplify_unop(struct instruction
*insn
)
418 if (dead_insn(insn
, &insn
->src1
, NULL
, NULL
))
420 if (constant(insn
->src1
))
421 return simplify_constant_unop(insn
);
425 static int simplify_one_memop(struct instruction
*insn
, pseudo_t orig
)
427 pseudo_t addr
= insn
->src
;
430 if (addr
->type
== PSEUDO_REG
) {
431 struct instruction
*def
= addr
->def
;
432 if (def
->opcode
== OP_SETVAL
&& def
->src
) {
433 kill_use(&insn
->src
);
434 use_pseudo(def
->src
, &insn
->src
);
435 return REPEAT_CSE
| REPEAT_SYMBOL_CLEANUP
;
437 if (def
->opcode
== OP_ADD
) {
457 warning(insn
->bb
->pos
, "crazy programmer");
459 insn
->offset
+= off
->value
;
460 use_pseudo(new, &insn
->src
);
461 remove_usage(addr
, &insn
->src
);
462 return REPEAT_CSE
| REPEAT_SYMBOL_CLEANUP
;
466 * We walk the whole chain of adds/subs backwards. That's not
467 * only more efficient, but it allows us to find looops.
469 static int simplify_memop(struct instruction
*insn
)
472 pseudo_t orig
= insn
->src
;
475 one
= simplify_one_memop(insn
, orig
);
481 static int simplify_cast(struct instruction
*insn
)
485 if (dead_insn(insn
, &insn
->src
, NULL
, NULL
))
487 if (insn
->opcode
== OP_PTRCAST
)
489 orig_size
= insn
->orig_type
? insn
->orig_type
->bit_size
: 0;
492 if (insn
->size
!= orig_size
)
494 return replace_with_pseudo(insn
, insn
->src
);
497 static int simplify_select(struct instruction
*insn
)
499 pseudo_t cond
, src1
, src2
;
501 if (dead_insn(insn
, &insn
->src1
, &insn
->src2
, &insn
->src3
))
507 if (constant(cond
) || src1
== src2
) {
508 pseudo_t
*kill
, take
;
509 kill_use(&insn
->src1
);
510 take
= cond
->value
? src1
: src2
;
511 kill
= cond
->value
? &insn
->src3
: &insn
->src2
;
513 replace_with_pseudo(insn
, take
);
516 if (constant(src1
) && constant(src2
)) {
517 long long val1
= src1
->value
;
518 long long val2
= src2
->value
;
520 /* The pair 0/1 is special - replace with SETNE/SETEQ */
521 if ((val1
| val2
) == 1) {
522 int opcode
= OP_SET_EQ
;
527 insn
->opcode
= opcode
;
528 /* insn->src1 is already cond */
529 insn
->src2
= src1
; /* Zero */
537 * Simplify "set_ne/eq $0 + br"
539 static int simplify_cond_branch(struct instruction
*br
, pseudo_t cond
, struct instruction
*def
, pseudo_t
*pp
)
541 use_pseudo(*pp
, &br
->cond
);
542 remove_usage(cond
, &br
->cond
);
543 if (def
->opcode
== OP_SET_EQ
) {
544 struct basic_block
*true = br
->bb_true
;
545 struct basic_block
*false = br
->bb_false
;
552 static int simplify_branch(struct instruction
*insn
)
554 pseudo_t cond
= insn
->cond
;
559 /* Constant conditional */
560 if (constant(cond
)) {
561 insert_branch(insn
->bb
, insn
, cond
->value
? insn
->bb_true
: insn
->bb_false
);
566 if (insn
->bb_true
== insn
->bb_false
) {
567 struct basic_block
*bb
= insn
->bb
;
568 struct basic_block
*target
= insn
->bb_false
;
569 remove_bb_from_list(&target
->parents
, bb
, 1);
570 remove_bb_from_list(&bb
->children
, target
, 1);
571 insn
->bb_false
= NULL
;
572 kill_use(&insn
->cond
);
577 /* Conditional on a SETNE $0 or SETEQ $0 */
578 if (cond
->type
== PSEUDO_REG
) {
579 struct instruction
*def
= cond
->def
;
581 if (def
->opcode
== OP_SET_NE
|| def
->opcode
== OP_SET_EQ
) {
582 if (constant(def
->src1
) && !def
->src1
->value
)
583 return simplify_cond_branch(insn
, cond
, def
, &def
->src2
);
584 if (constant(def
->src2
) && !def
->src2
->value
)
585 return simplify_cond_branch(insn
, cond
, def
, &def
->src1
);
587 if (def
->opcode
== OP_SEL
) {
588 if (constant(def
->src2
) && constant(def
->src3
)) {
589 long long val1
= def
->src2
->value
;
590 long long val2
= def
->src3
->value
;
591 if (!val1
&& !val2
) {
592 insert_branch(insn
->bb
, insn
, insn
->bb_false
);
596 insert_branch(insn
->bb
, insn
, insn
->bb_true
);
600 struct basic_block
*true = insn
->bb_true
;
601 struct basic_block
*false = insn
->bb_false
;
602 insn
->bb_false
= true;
603 insn
->bb_true
= false;
605 use_pseudo(def
->src1
, &insn
->cond
);
606 remove_usage(cond
, &insn
->cond
);
614 static int simplify_switch(struct instruction
*insn
)
616 pseudo_t cond
= insn
->cond
;
618 struct multijmp
*jmp
;
622 val
= insn
->cond
->value
;
624 FOR_EACH_PTR(insn
->multijmp_list
, jmp
) {
626 if (jmp
->begin
> jmp
->end
)
628 if (val
>= jmp
->begin
&& val
<= jmp
->end
)
630 } END_FOR_EACH_PTR(jmp
);
631 warning(insn
->bb
->pos
, "Impossible case statement");
635 insert_branch(insn
->bb
, insn
, jmp
->target
);
639 int simplify_instruction(struct instruction
*insn
)
643 switch (insn
->opcode
) {
644 case OP_BINARY
... OP_BINCMP_END
:
645 return simplify_binop(insn
);
647 case OP_NOT
: case OP_NEG
:
648 return simplify_unop(insn
);
649 case OP_LOAD
: case OP_STORE
:
650 return simplify_memop(insn
);
652 if (dead_insn(insn
, NULL
, NULL
, NULL
))
653 return REPEAT_CSE
| REPEAT_SYMBOL_CLEANUP
;
654 return replace_with_pseudo(insn
, insn
->symbol
);
657 return simplify_cast(insn
);
659 if (dead_insn(insn
, NULL
, NULL
, NULL
)) {
663 return clean_up_phi(insn
);
665 if (dead_insn(insn
, &insn
->phi_src
, NULL
, NULL
))
669 return simplify_select(insn
);
671 return simplify_branch(insn
);
673 return simplify_switch(insn
);