PR64682 is a problem in distribute_notes, where it has trouble putting
a REG_DEAD note for a reg that is set twice in the right spot. My fix
for that did the wrong thing for PR69567. And then my attempted fix
for that one made PR64682 fail again.
Instead, let's just lose the note in such complicated cases, like we
already do in certain similar cases.
Tested on powerpc64-linux and x86_64-linux. Also built Linux kernels
for some 30 supported targets; no difference in generated code was
observed.
Committing to trunk.
HJ, I tested this on GCC 5 for x86_64-linux, the failure is gone;
could you test it on your setup before I apply it there though?
Segher
2016-02-11 Segher Boessenkool <seg...@kernel.crashing.org>
PR rtl-optimization/64682
PR rtl-optimization/69567
PR rtl-optimization/69737
* combine.c (distribute_notes) <REG_DEAD>: If the register is set
in I2 as well, just lose it.
---
gcc/combine.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)
diff --git a/gcc/combine.c b/gcc/combine.c
index 3609b94..24dcefa 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -13901,7 +13901,6 @@ distribute_notes (rtx notes, rtx_insn *from_insn,
rtx_insn *i3, rtx_insn *i2,
tem_insn = from_insn;
else
{
- tem_insn = i3;
if (from_insn
&& CALL_P (from_insn)
&& find_reg_fusage (from_insn, USE, XEXP (note, 0)))
@@ -13910,14 +13909,7 @@ distribute_notes (rtx notes, rtx_insn *from_insn,
rtx_insn *i3, rtx_insn *i2,
place = i3;
else if (i2 != 0 && next_nonnote_nondebug_insn (i2) == i3
&& reg_referenced_p (XEXP (note, 0), PATTERN (i2)))
- {
- place = i2;
- /* If the new I2 sets the same register that is marked dead
- in the note, the note now should not be put on I2, as the
- note refers to a previous incarnation of the reg. */
- if (reg_set_p (XEXP (note, 0), PATTERN (i2)))
- tem_insn = i2;
- }
+ place = i2;
else if ((rtx_equal_p (XEXP (note, 0), elim_i2)
&& !(i2mod
&& reg_overlap_mentioned_p (XEXP (note, 0),
@@ -13925,6 +13917,12 @@ distribute_notes (rtx notes, rtx_insn *from_insn,
rtx_insn *i3, rtx_insn *i2,
|| rtx_equal_p (XEXP (note, 0), elim_i1)
|| rtx_equal_p (XEXP (note, 0), elim_i0))
break;
+ tem_insn = i3;
+ /* If the new I2 sets the same register that is marked dead
+ in the note, we do not know where to put the note.
+ Give up. */
+ if (i2 != 0 && reg_set_p (XEXP (note, 0), PATTERN (i2)))
+ break;
}
if (place == 0)
--
1.9.3
