regrename: Don't rename restores

A restore is supposed to restore some certain register.  Restoring it
into some other register will not work.  Don't.

	* regrename.c (build_def_use): Invalidate chains that have a
	REG_CFA_RESTORE on some instruction.

From-SVN: r241061

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 7793544..9b66e88 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,10 @@
 2016-10-12  Segher Boessenkool  <segher@kernel.crashing.org>
 
+       * regrename.c (build_def_use): Invalidate chains that have a
+       REG_CFA_RESTORE on some instruction.
+
+2016-10-12  Segher Boessenkool  <segher@kernel.crashing.org>
+
        * dce.c (delete_unmarked_insns): Don't delete instructions with
        a REG_CFA_RESTORE note.
 

diff --git a/gcc/regrename.c b/gcc/regrename.c
index 3509e8b..e0d2dd1 100644 (file)
--- 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)))