(delete_computation): Derived from delete_jump.

(delete_jump): Use delete_computation.

From-SVN: r1944

gcc/jump.c

@@ -108,6 +108,7 @@ void redirect_tablejump ();
 static int delete_labelref_insn ();
 static void mark_jump_label ();
 void delete_jump ();
+void delete_computation ();
 static void delete_from_jump_chain ();
 static int tension_vector_labels ();
 static void find_cross_jump ();
@@ -2820,13 +2821,12 @@ delete_jump (insn)
      rtx insn;
 {
   register rtx x = PATTERN (insn);
-  register rtx prev;
 
   if (GET_CODE (x) == SET
       && GET_CODE (SET_DEST (x)) == PC)
     {
-      prev = prev_nonnote_insn (insn);
 #ifdef HAVE_cc0
+      rtx prev = prev_nonnote_insn (insn);
       /* We assume that at this stage
 	 CC's are always set explicitly
 	 and always immediately before the jump that
@@ -2844,25 +2844,37 @@ delete_jump (insn)
 	    REG_NOTES (prev) = gen_rtx (EXPR_LIST, REG_UNUSED,
 					cc0_rtx, REG_NOTES (prev));
 	}
-#else
-      {
-	rtx note;
+#endif
+      /* Now delete the jump insn itself.  */
+      delete_computation (insn);
+    }
+}
 
-	/* If we are running before flow.c, we need do nothing since flow.c
-	   will delete the set of the condition code if it is dead.  We also
-	   can't know if the register being used as the condition code is
+/* Delete INSN and recursively delete insns that compute values used only
+   by INSN.  This uses the REG_DEAD notes computed during flow analysis.
+   If we are running before flow.c, we need do nothing since flow.c will
+   delete dead code.  We also can't know if the registers being used are
    dead or not at this point.
 
-	   Otherwise, look at all our REG_DEAD notes.  If a previous insn
-	   does nothing other than set a register that dies in this jump,
-	   we can delete the insn.  */
+   Otherwise, look at all our REG_DEAD notes.  If a previous insn does
+   nothing other than set a register that dies in this insn, we can delete
+   that insn as well.  */
 
-	for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
+void
+delete_computation (insn)
+     rtx insn;
+{
+#ifndef HAVE_cc0
+  rtx note, next;
+
+  for (note = REG_NOTES (insn); note; note = next)
     {
       rtx our_prev;
 
+      next = XEXP (note, 1);
+
       if (REG_NOTE_KIND (note) != REG_DEAD
-		/* Verify that the REG_NOTE has a legal value.  */
+	  /* Verify that the REG_NOTE is legitimate.  */
 	  || GET_CODE (XEXP (note, 0)) != REG)
 	continue;
 
@@ -2903,28 +2915,29 @@ delete_jump (insn)
 		    }
 
 		  if (i == XVECLEN (PATTERN (our_prev), 0))
-			  delete_insn (our_prev);
+		    delete_computation (our_prev);
 		}
 	      else if (GET_CODE (PATTERN (our_prev)) == SET
 		       && SET_DEST (PATTERN (our_prev)) == XEXP (note, 0))
-		      delete_insn (our_prev);
+		delete_computation (our_prev);
 
 	      break;
 	    }
 
-		/* If OUR_PREV references the register that dies here,
-		   it is an additional use.  Hence any prior SET isn't
-		   dead.  */
+	  /* If OUR_PREV references the register that dies here, it is an
+	     additional use.  Hence any prior SET isn't dead.  However, this
+	     insn becomes the new place for the REG_DEAD note.  */
 	  if (reg_overlap_mentioned_p (XEXP (note, 0),
 				       PATTERN (our_prev)))
+	    {
+	      XEXP (note, 1) = REG_NOTES (our_prev);
+	      REG_NOTES (our_prev) = note;
 	      break;
 	    }
 	}
     }
-#endif
-      /* Now delete the jump insn itself.  */
+#endif /* Don't HAVE_cc0 */
   delete_insn (insn);
-    }
 }
 
 /* Delete insn INSN from the chain of insns and update label ref counts.