| Message ID | f92b642e30f141bd5a2910b4b422857384d4369d.1474616087.git.segher@kernel.crashing.org |
|---|---|
| State | New |
| Headers | show |
On 09/23/2016 02:21 AM, Segher Boessenkool wrote: > A restore is supposed to restore some certain register. Restoring it > into some other register will not work. Don't. > > > 2016-09-23 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 | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/gcc/regrename.c b/gcc/regrename.c > index 54c7768..00a5d02 100644 > --- a/gcc/regrename.c > +++ b/gcc/regrename.c > @@ -1867,6 +1867,12 @@ 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))) Seems like a good thing regardless of the shrink-wrapping changes. There's a comment about 200 lines earlier (egad) which outlines the steps. Can you please add a comment there too. It would probably be a good idea to refactor build_def_use a bit, but I'd understand if you don't want to tackle that. I don't think that desire should block this patch. As I've said before, I'm not sure we're getting CFA notes right, particularly on the older ports, but I don't think that should block this patch. With the earlier comment update change this is OK. jeff
diff --git a/gcc/regrename.c b/gcc/regrename.c index 54c7768..00a5d02 100644 --- a/gcc/regrename.c +++ b/gcc/regrename.c @@ -1867,6 +1867,12 @@ 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)))