(distribute_notes): If can't find place for REG_DEAD note, add an INSN

with a USE to hold it.

From-SVN: r8625

diff --git a/gcc/combine.c b/gcc/combine.c
index bd7516084096004d61a35f2ce34751c77fe93178..f7415aea817237269ec466a63e0dcdc142169acc 100644 (file)
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -10515,49 +10515,50 @@ distribute_notes (notes, from_insn, i3, i2, elim_i2, elim_i1)
            reg_n_refs[REGNO (XEXP (note, 0))] = 3;
 
          if (place == 0)
-           for (tem = prev_nonnote_insn (i3);
-                tem && (GET_CODE (tem) == INSN
-                        || GET_CODE (tem) == CALL_INSN);
-                tem = prev_nonnote_insn (tem))
-             {
-               /* If the register is being set at TEM, see if that is all
-                  TEM is doing.  If so, delete TEM.  Otherwise, make this
-                  into a REG_UNUSED note instead.  */
-               if (reg_set_p (XEXP (note, 0), PATTERN (tem)))
-                 {
-                   rtx set = single_set (tem);
+           {
+             for (tem = prev_nonnote_insn (i3);
+                  place == 0 && tem
+                  && (GET_CODE (tem) == INSN || GET_CODE (tem) == CALL_INSN);
+                  tem = prev_nonnote_insn (tem))
+               {
+                 /* If the register is being set at TEM, see if that is all
+                    TEM is doing.  If so, delete TEM.  Otherwise, make this
+                    into a REG_UNUSED note instead.  */
+                 if (reg_set_p (XEXP (note, 0), PATTERN (tem)))
+                   {
+                     rtx set = single_set (tem);
 
-                   /* Verify that it was the set, and not a clobber that
-                      modified the register.  */
+                     /* Verify that it was the set, and not a clobber that
+                        modified the register.  */
 
-                   if (set != 0 && ! side_effects_p (SET_SRC (set))
-                       && rtx_equal_p (XEXP (note, 0), SET_DEST (set)))
-                     {
-                       /* Move the notes and links of TEM elsewhere.
-                          This might delete other dead insns recursively. 
-                          First set the pattern to something that won't use
-                          any register.  */
+                     if (set != 0 && ! side_effects_p (SET_SRC (set))
+                         && rtx_equal_p (XEXP (note, 0), SET_DEST (set)))
+                       {
+                         /* Move the notes and links of TEM elsewhere.
+                            This might delete other dead insns recursively. 
+                            First set the pattern to something that won't use
+                            any register.  */
 
-                       PATTERN (tem) = pc_rtx;
+                         PATTERN (tem) = pc_rtx;
 
-                       distribute_notes (REG_NOTES (tem), tem, tem,
-                                         NULL_RTX, NULL_RTX, NULL_RTX);
-                       distribute_links (LOG_LINKS (tem));
+                         distribute_notes (REG_NOTES (tem), tem, tem,
+                                           NULL_RTX, NULL_RTX, NULL_RTX);
+                         distribute_links (LOG_LINKS (tem));
 
-                       PUT_CODE (tem, NOTE);
-                       NOTE_LINE_NUMBER (tem) = NOTE_INSN_DELETED;
-                       NOTE_SOURCE_FILE (tem) = 0;
-                     }
-                   else
-                     {
-                       PUT_REG_NOTE_KIND (note, REG_UNUSED);
-
-                       /*  If there isn't already a REG_UNUSED note, put one
-                           here.  */
-                       if (! find_regno_note (tem, REG_UNUSED,
-                                              REGNO (XEXP (note, 0))))
-                         place = tem;
-                       break;
+                         PUT_CODE (tem, NOTE);
+                         NOTE_LINE_NUMBER (tem) = NOTE_INSN_DELETED;
+                         NOTE_SOURCE_FILE (tem) = 0;
+                       }
+                     else
+                       {
+                         PUT_REG_NOTE_KIND (note, REG_UNUSED);
+                         
+                         /*  If there isn't already a REG_UNUSED note, put one
+                             here.  */
+                         if (! find_regno_note (tem, REG_UNUSED,
+                                                REGNO (XEXP (note, 0))))
+                           place = tem;
+                         break;
                      }
                  }
                else if (reg_referenced_p (XEXP (note, 0), PATTERN (tem))
@@ -10567,7 +10568,18 @@ distribute_notes (notes, from_insn, i3, i2, elim_i2, elim_i1)
                    place = tem;
                    break;
                  }
-             }
+               }
+             
+             /* If we haven't found an insn for the death note and it
+                is still a REG_DEAD note, but we have hit a CODE_LABEL,
+                insert a USE insn for the register at that label and
+                put the death node there.  This prevents problems with
+                call-state tracking in caller-save.c.  */
+             if (REG_NOTE_KIND (note) == REG_DEAD && place == 0 && tem != 0)
+               place
+                 = emit_insn_after (gen_rtx (USE, VOIDmode, XEXP (note, 0)),
+                                    tem);
+           }
 
          /* If the register is set or already dead at PLACE, we needn't do
             anything with this note if it is still a REG_DEAD note.