Now that LOG_LINKS are per regno, we can distribute them on PARALLELs
just fine. Do so. This makes PARALLELs not lose their LOG_LINKS early
when e.g. a trivial reg-reg move is combined, so that they can be used
in more useful combinations as well.
2014-11-14 Segher Boessenkool <seg...@kernel.crashing.org>
gcc/
* combine.c (distribute_links): Handle multiple SETs.
---
gcc/combine.c | 52 +++++++++++++++++++++++++++++++++++++---------------
1 file changed, 37 insertions(+), 15 deletions(-)
diff --git a/gcc/combine.c b/gcc/combine.c
index cf184db..8c7f052 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -13832,24 +13832,46 @@ distribute_links (struct insn_link *links)
next_link = link->next;
- /* If the insn that this link points to is a NOTE or isn't a single
- set, ignore it. In the latter case, it isn't clear what we
- can do other than ignore the link, since we can't tell which
- register it was for. Such links wouldn't be used by combine
- anyway.
-
- It is not possible for the destination of the target of the link to
- have been changed by combine. The only potential of this is if we
- replace I3, I2, and I1 by I3 and I2. But in that case the
- destination of I2 also remains unchanged. */
-
- if (NOTE_P (link->insn)
- || (set = single_set (link->insn)) == 0)
+ /* If the insn that this link points to is a NOTE, ignore it. */
+ if (NOTE_P (link->insn))
+ continue;
+
+ set = 0;
+ rtx pat = PATTERN (link->insn);
+ if (GET_CODE (pat) == SET)
+ set = pat;
+ else if (GET_CODE (pat) == PARALLEL)
+ {
+ int i;
+ for (i = 0; i < XVECLEN (pat, 0); i++)
+ {
+ set = XVECEXP (pat, 0, i);
+ if (GET_CODE (set) != SET)
+ continue;
+
+ reg = SET_DEST (set);
+ while (GET_CODE (reg) == ZERO_EXTRACT
+ || GET_CODE (reg) == STRICT_LOW_PART
+ || GET_CODE (reg) == SUBREG)
+ reg = XEXP (reg, 0);
+
+ if (!REG_P (reg))
+ continue;
+
+ if (REGNO (reg) == link->regno)
+ break;
+ }
+ if (i == XVECLEN (pat, 0))
+ continue;
+ }
+ else
continue;
reg = SET_DEST (set);
- while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT
- || GET_CODE (reg) == STRICT_LOW_PART)
+
+ while (GET_CODE (reg) == ZERO_EXTRACT
+ || GET_CODE (reg) == STRICT_LOW_PART
+ || GET_CODE (reg) == SUBREG)
reg = XEXP (reg, 0);
/* A LOG_LINK is defined as being placed on the first insn that uses
--
1.8.1.4
