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loop.c (strength_reduce): Insert sets of derived givs at every biv increment, even if it's the only one.

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* loop.c (strength_reduce): Insert sets of derived givs at every
	biv increment, even if it's the only one.

From-SVN: r27549
This commit is contained in:
J"orn Rennecke 1999-06-16 11:46:14 +00:00 committed by Joern Rennecke
parent 4e61a9695a
commit 1b786838b1
2 changed files with 27 additions and 14 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
Wed Jun 16 19:44:33 1999 J"orn Rennecke <amylaar@cygnus.co.uk>
* loop.c (strength_reduce): Insert sets of derived givs at every
biv increment, even if it's the only one.
Wed Jun 16 10:33:02 1999 Jason Merrill <jason@yorick.cygnus.com>
* dwarfout.c (add_incomplete_type): New fn.

36
gcc/loop.c
View File

@ -4768,21 +4768,29 @@ strength_reduce (scan_start, end, loop_top, insn_count,
= replace_rtx (PATTERN (v->insn), d->dest_reg, d->new_reg);
PATTERN (v->insn)
= replace_rtx (PATTERN (v->insn), v->dest_reg, v->new_reg);
if (bl->biv_count != 1)
/* For each place where the biv is incremented, add an
insn to set the new, reduced reg for the giv.
We used to do this only for biv_count != 1, but
this fails when there is a giv after a single biv
increment, e.g. when the last giv was expressed as
pre-decrement. */
for (tv = bl->biv; tv; tv = tv->next_iv)
{
/* For each place where the biv is incremented, add an
insn to set the new, reduced reg for the giv. */
for (tv = bl->biv; tv; tv = tv->next_iv)
{
/* We always emit reduced giv increments before the
biv increment when bl->biv_count != 1. So by
emitting the add insns for derived givs after the
biv increment, they pick up the updated value of
the reduced giv. */
emit_insn_after (copy_rtx (PATTERN (v->insn)),
tv->insn);
}
/* We always emit reduced giv increments before the
biv increment when bl->biv_count != 1. So by
emitting the add insns for derived givs after the
biv increment, they pick up the updated value of
the reduced giv.
If the reduced giv is processed with
auto_inc_opt == 1, then it is incremented earlier
than the biv, hence we'll still pick up the right
value.
If it's processed with auto_inc_opt == -1,
that implies that the biv increment is before the
first reduced giv's use. The derived giv's lifetime
is after the reduced giv's lifetime, hence in this
case, the biv increment doesn't matter. */
emit_insn_after (copy_rtx (PATTERN (v->insn)), tv->insn);
}
continue;
}