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compile.c: useless jump elimination

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* compile.c (iseq_peephole_optimize): eliminate useless if/unless
  just before jump.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59655 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
nobu 2017-08-25 03:33:32 +00:00
parent 5ccf7b0610
commit ed3a575b59
1 changed files with 20 additions and 3 deletions
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23
compile.c
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@ -866,7 +866,6 @@ INSERT_ELEM_PREV(LINK_ELEMENT *elem1, LINK_ELEMENT *elem2)
}
}
#if 0
/*
* elemX, elem1, elemY => elemX, elem2, elemY
*/
@ -882,7 +881,6 @@ REPLACE_ELEM(LINK_ELEMENT *elem1, LINK_ELEMENT *elem2)
elem1->next->prev = elem2;
}
}
#endif
static void
REMOVE_ELEM(LINK_ELEMENT *elem)
@ -2211,7 +2209,8 @@ iseq_peephole_optimize(rb_iseq_t *iseq, LINK_ELEMENT *list, const int do_tailcal
else if ((piobj = (INSN *)get_prev_insn(iobj)) != 0 &&
(IS_INSN_ID(piobj, branchif) ||
IS_INSN_ID(piobj, branchunless))) {
if (niobj == (INSN *)get_destination_insn(piobj)) {
INSN *pdiobj = (INSN *)get_destination_insn(piobj);
if (niobj == pdiobj) {
/*
* useless jump elimination (if/unless destination):
* if L1
@ -2231,6 +2230,24 @@ iseq_peephole_optimize(rb_iseq_t *iseq, LINK_ELEMENT *list, const int do_tailcal
replace_destination(piobj, iobj);
REMOVE_ELEM(&iobj->link);
}
else if (diobj == pdiobj) {
/*
* useless jump elimination (if/unless before jump):
* L1:
* ...
* if L1
* jump L1
*
* ==>
* L1:
* ...
* pop
* jump L1
*/
INSN *popiobj = new_insn_core(iseq, iobj->line_no,
BIN(pop), 0, 0);
REPLACE_ELEM(&piobj->link, &popiobj->link);
}
}
else if (remove_unreachable_chunk(iseq, iobj->link.next)) {
goto again;