(thread_prologue_and_epilogue_insns): For the

epilogue, put USE insns immediately before the return insn.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@5142 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/function.c b/gcc/function.c
index 93fce64..21d58f0 100644 (file)
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -4846,26 +4846,48 @@ thread_prologue_and_epilogue_insns (f)
       /* If we end with a BARRIER, we don't need an epilogue.  */
       if (! (prev && GET_CODE (prev) == BARRIER))
        {
-         rtx tail, seq;
+         rtx tail, seq, tem;
+         rtx first_use = 0;
+         rtx last_use = 0;
 
-         /* The last basic block ends with a NOTE_INSN_EPILOGUE_BEG,
-            the epilogue insns (this must include the jump insn that
-            returns), USE insns ad the end of a function, and a BARRIER.  */
+         /* The last basic block ends with a NOTE_INSN_EPILOGUE_BEG, the
+            epilogue insns, the USE insns at the end of a function,
+            the jump insn that returns, and then a BARRIER.  */
 
-         emit_barrier_after (insn);
-
-         /* Place the epilogue before the USE insns at the end of a
-            function.  */
+         /* Move the USE insns at the end of a function onto a list.  */
          while (prev
                 && GET_CODE (prev) == INSN
                 && GET_CODE (PATTERN (prev)) == USE)
            {
-             insn = PREV_INSN (prev);
+             tem = prev;
              prev = prev_nonnote_insn (prev);
+
+             NEXT_INSN (PREV_INSN (tem)) = NEXT_INSN (tem);
+             PREV_INSN (NEXT_INSN (tem)) = PREV_INSN (tem);
+             if (! first_use)
+               first_use = tem;
+             if (last_use)
+               NEXT_INSN (last_use) = tem;
+             else
+               last_use = tem;
            }
 
+         emit_barrier_after (insn);
+
          seq = gen_epilogue ();
          tail = emit_jump_insn_after (seq, insn);
+
+         /* Insert the USE insns immediately before the return insn, which
+            must be the first instruction before the final barrier.  */
+         if (first_use)
+           {
+             tem = prev_nonnote_insn (get_last_insn ());
+             NEXT_INSN (PREV_INSN (tem)) = first_use;
+             PREV_INSN (first_use) = PREV_INSN (tem);
+             PREV_INSN (tem) = last_use;
+             NEXT_INSN (last_use) = tem;
+           }
+
          emit_note_after (NOTE_INSN_EPILOGUE_BEG, insn);
 
          /* Include the new epilogue insns in the last block.  Ignore