Re: [avr-gcc-list] Small frame optimization: Butterfly -= 90 bytes

[Dmitry K.]

19 Jan 2004 08:33 Dmitry K. wrote:
> It has reduced the size of code Butterfly by 90 bytes (with
> a simultaneous prize in speed).
>

Where the attachment disappeared?
I shall insert it in a body of the letter:

Patch for avr.c:
> ----------------------------------------------------------------------
>     FOR LOOCKING OF IDEA ONLY, NOT USE FOR WORK.
>   THERE ARE IMPERFECTIONS AND MISTAKES ARE POSSIBLE, DID NOT TEST.
> ----------------------------------------------------------------------

--- avr.c.orig  2002-10-25 07:07:21.000000000 +1100
+++ avr.c       2004-01-18 19:28:24.000000000 +1000
@@ -717,6 +717,7 @@
              fprintf (file, "\t" AS1 (push,%s) "\n", avr_regnames[reg]);
            }
        }
+#if 0
       if (frame_pointer_needed)
        {
          {
@@ -746,6 +747,43 @@
              }
          }
        }
+#else
+       if (frame_pointer_needed)
+       {
+           fputs ("\t" AS1(push,r28) "\n", file);
+           fputs ("\t" AS1(push,r29) "\n", file);
+           prologue_size += 2;
+           if ( size > 10
+               || (size && (interrupt_func_p || signal_func_p)) )
+           {
+               fprintf (file, "\t"
+                       AS2(in,r28,__SP_L__) CR_TAB
+                       AS2(in,r29,__SP_H__) "\n");
+               prologue_size += 2;
+               fputs ("\t", file);
+               prologue_size += out_adj_frame_ptr (file, size);
+               if (interrupt_func_p)
+                   prologue_size += out_set_stack_ptr (file, 1, 1);
+               else if (signal_func_p)
+                   prologue_size += out_set_stack_ptr (file, 0, 0);
+               else
+                   prologue_size += out_set_stack_ptr (file, -1, -1);
+           } else if (size) {
+               int i;
+               for (i= size/2; i; i--) {
+                   fputs ("\t" AS1(rcall,.) "\n", file);
+                   prologue_size += 1;
+               }
+               if (size % 2) {
+                   fputs ("\t" AS1(push,__zero_reg__) "\n", file);
+                   prologue_size += 1;
+               }
+               fputs ("\t" AS2(in,r28,__SP_L__) "\n", file);
+               fputs ("\t" AS2(in,r29,__SP_H__) "\n", file);
+               prologue_size += 2;
+           }
+       }
+#endif
     }

  out:
@@ -848,6 +886,7 @@

       if (frame_pointer_needed)
        {
+#if 0
          if (size)
            {
              fputs ("\t", file);
@@ -862,6 +901,24 @@
                  epilogue_size += out_set_stack_ptr (file, -1, -1);
                }
            }
+#else
+           if ( size > 5
+               || (size && (interrupt_func_p || signal_func_p)) )
+           {
+               fputs ("\t", file);
+               epilogue_size += out_adj_frame_ptr (file, -size);
+               if (interrupt_func_p || signal_func_p)
+                   epilogue_size += out_set_stack_ptr (file, -1, 0);
+               else
+                   epilogue_size += out_set_stack_ptr (file, -1, -1);
+           } else if (size) {
+               int i;
+               for (i= size; i; i--) {
+                   fputs ("\t" AS1(pop,__tmp_reg__) "\n", file);
+                   epilogue_size += 1;
+               }
+           }
+#endif
          fprintf (file, "\t"
                   AS1 (pop,r29) CR_TAB
                   AS1 (pop,r28) "\n");