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 <seg...@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