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[PATCH 3/6] regrename: Don't rename restores
- From: Segher Boessenkool <segher at kernel dot crashing dot org>
- To: gcc-patches at gcc dot gnu dot org
- Cc: law at redhat dot com, dje dot gcc at gmail dot com, Segher Boessenkool <segher at kernel dot crashing dot org>
- Date: Mon, 3 Oct 2016 13:48:20 +0000
- Subject: [PATCH 3/6] regrename: Don't rename restores
- Authentication-results: sourceware.org; auth=none
- References: <cover.1475501415.git.segher@kernel.crashing.org>
- References: <cover.1475501415.git.segher@kernel.crashing.org>
A restore is supposed to restore some certain register. Restoring it
into some other register will not work. Don't.
2016-06-07 Segher Boessenkool <segher@kernel.crashing.org>
* regrename.c (build_def_use): Invalidate chains that have a
REG_CFA_RESTORE on some instruction.
---
gcc/regrename.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/gcc/regrename.c b/gcc/regrename.c
index 3509e8b..e0d2dd1 100644
--- a/gcc/regrename.c
+++ b/gcc/regrename.c
@@ -1655,6 +1655,7 @@ 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.
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
@@ -1867,6 +1868,12 @@ build_def_use (basic_block bb)
scan_rtx (insn, &XEXP (note, 0), NO_REGS, terminate_dead,
OP_IN);
}
+
+ /* Step 8: Kill the chains involving register restores. Those
+ should restore _that_ 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);
}
else if (DEBUG_INSN_P (insn)
&& !VAR_LOC_UNKNOWN_P (INSN_VAR_LOCATION_LOC (insn)))
--
1.9.3