[PATCH, moxie] clean up function prologues

[Anthony Green]

The prologue code for functions with large static stack space
requirements was really ugly on moxie.  This patch cleans things up
and I am committing this change.

2012-09-07  Anthony Green  <gr...@moxielogic.com>

        * config/moxie/moxie.c (moxie_expand_prologue): Optimize prologue
        for functions with large static stack requirements.
        (moxie_expand_epilogue): Use $r12 instead of $r5 for pulling saved
        values off of the stack.


diff --git a/gcc/gcc/config/moxie/moxie.c b/gcc/gcc/config/moxie/moxie.c
index d70eaac..567e759 100644
--- a/gcc/gcc/config/moxie/moxie.c
+++ b/gcc/gcc/config/moxie/moxie.c
@@ -1,5 +1,5 @@
 /* Target Code for moxie
-   Copyright (C) 2008, 2009, 2010, 2011  Free Software Foundation
+   Copyright (C) 2008, 2009, 2010, 2011, 2012  Free Software Foundation
    Contributed by Anthony Green.

    This file is part of GCC.
@@ -293,8 +293,8 @@ moxie_expand_prologue (void)

   if (cfun->machine->size_for_adjusting_sp > 0)
     {
-      int i = cfun->machine->size_for_adjusting_sp;
-      while (i > 255)
+      int i = cfun->machine->size_for_adjusting_sp;
+      while ((i >= 255) && (i <= 510))
        {
          insn = emit_insn (gen_subsi3 (stack_pointer_rtx,
                                        stack_pointer_rtx,
@@ -302,13 +302,23 @@ moxie_expand_prologue (void)
          RTX_FRAME_RELATED_P (insn) = 1;
          i -= 255;
        }
-      if (i > 0)
+      if (i <= 255)
        {
          insn = emit_insn (gen_subsi3 (stack_pointer_rtx,
                                        stack_pointer_rtx,
                                        GEN_INT (i)));
          RTX_FRAME_RELATED_P (insn) = 1;
        }
+      else
+       {
+         rtx reg = gen_rtx_REG (SImode, MOXIE_R12);
+         insn = emit_move_insn (reg, GEN_INT (i));
+         RTX_FRAME_RELATED_P (insn) = 1;
+         insn = emit_insn (gen_subsi3 (stack_pointer_rtx,
+                                       stack_pointer_rtx,
+                                       reg));
+         RTX_FRAME_RELATED_P (insn) = 1;
+       }
     }
 }

@@ -320,7 +330,7 @@ moxie_expand_epilogue (void)

   if (cfun->machine->callee_saved_reg_size != 0)
     {
-      reg = gen_rtx_REG (Pmode, MOXIE_R5);
+      reg = gen_rtx_REG (Pmode, MOXIE_R12);
       if (cfun->machine->callee_saved_reg_size <= 255)
        {
          emit_move_insn (reg, hard_frame_pointer_rtx);