We should never change the destination of a REG_CFA_REGISTER, just
like for insns with a REG_CFA_RESTORE, because we need to have the
same control flow information on all branches that join. It is very
doubtful that renaming the scratch registers used for prologue/epilogue
will help anything either.
Bootstrapped and tested on powerpc64-linux {-m32,-m64}. Is this
okay for trunk?
Segher
2018-05-08 Segher Boessenkool <seg...@kernel.crashing.org>
PR rtl-optimization/85645
* regrename.c (build_def_use): Also kill the chains that include the
destination of a REG_CFA_REGISTER note.
---
gcc/regrename.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/gcc/regrename.c b/gcc/regrename.c
index 4575481..8424093 100644
--- a/gcc/regrename.c
+++ b/gcc/regrename.c
@@ -1661,7 +1661,8 @@ build_def_use (basic_block bb)
(6) For any non-earlyclobber write we find in an operand, make
a new chain or mark the hard register as live.
(7) For any REG_UNUSED, close any chains we just opened.
- (8) For any REG_CFA_RESTORE, kill any chain containing it.
+ (8) For any REG_CFA_RESTORE or REG_CFA_REGISTER, kill any chain
+ containing its dest.
We cannot deal with situations where we track a reg in one mode
and see a reference in another mode; these will cause the chain
@@ -1882,10 +1883,20 @@ build_def_use (basic_block bb)
}
/* Step 8: Kill the chains involving register restores. Those
- should restore _that_ register. */
+ should restore _that_ register. Similar for REG_CFA_REGISTER. */
for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
- if (REG_NOTE_KIND (note) == REG_CFA_RESTORE)
- scan_rtx (insn, &XEXP (note, 0), NO_REGS, mark_all_read, OP_IN);
+ if (REG_NOTE_KIND (note) == REG_CFA_RESTORE
+ || REG_NOTE_KIND (note) == REG_CFA_REGISTER)
+ {
+ rtx *x = &XEXP (note, 0);
+ if (!*x)
+ x = &PATTERN (insn);
+ if (GET_CODE (*x) == PARALLEL)
+ x = &XVECEXP (*x, 0, 0);
+ if (GET_CODE (*x) == SET)
+ x = &SET_DEST (*x);
+ scan_rtx (insn, x, NO_REGS, mark_all_read, OP_IN);
+ }
}
else if (DEBUG_BIND_INSN_P (insn)
&& !VAR_LOC_UNKNOWN_P (INSN_VAR_LOCATION_LOC (insn)))
--
1.8.3.1
