[3.3/mainline] Speed up nonoptimizing compilation II

[Jan Hubicka <jh at suse dot cz>]

Hi,
tidy_fallthru_edges is subset of cfg_cleanup(0) and yet it is slower.  I
believe it is useless at both places it is called - we always
cleanup_cfg after find_basic_blocks and delete_unreachable_block is
either called from cfgcleanup  or to avoid dataflow to crash on
unreachable blocks so both is OK.

I am installing this to rtlopt branch so we see if it makes any
implications on code quality, but I would be really surprised.
Honza

Fri Feb 21 13:32:35 CET 2003  Jan Hubicka  <jh at suse dot cz>
	* basic-block.h (tidy_fallthru_edges): Kill.
	* cfgrtl.c (tidy_fallthru_edges): Kill.
	* cfgbuild.c (find_basic_blocks): Do not call tidy_fallthru_edges.
	* cfgcleanup.c (delete_unreachable_blocks): Likewise.
Index: basic-block.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/basic-block.h,v
retrieving revision 1.169
diff -c -3 -p -r1.169 basic-block.h
*** basic-block.h	6 Feb 2003 10:02:31 -0000	1.169
--- basic-block.h	21 Feb 2003 12:31:36 -0000
*************** extern void clear_bb_flags		PARAMS ((voi
*** 361,367 ****
  extern void merge_blocks_nomove		PARAMS ((basic_block, basic_block));
  extern void tidy_fallthru_edge		PARAMS ((edge, basic_block,
  						 basic_block));
- extern void tidy_fallthru_edges		PARAMS ((void));
  extern void flow_reverse_top_sort_order_compute	PARAMS ((int *));
  extern int flow_depth_first_order_compute	PARAMS ((int *, int *));
  extern void flow_preorder_transversal_compute	PARAMS ((int *));
--- 361,366 ----
Index: cfgbuild.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cfgbuild.c,v
retrieving revision 1.32
diff -c -3 -p -r1.32 cfgbuild.c
*** cfgbuild.c	6 Feb 2003 10:02:32 -0000	1.32
--- cfgbuild.c	21 Feb 2003 12:31:36 -0000
*************** find_basic_blocks (f, nregs, file)
*** 649,658 ****
    /* Discover the edges of our cfg.  */
    make_edges (label_value_list, ENTRY_BLOCK_PTR->next_bb, EXIT_BLOCK_PTR->prev_bb, 0);
  
-   /* Do very simple cleanup now, for the benefit of code that runs between
-      here and cleanup_cfg, e.g. thread_prologue_and_epilogue_insns.  */
-   tidy_fallthru_edges ();
- 
  #ifdef ENABLE_CHECKING
    verify_flow_info ();
  #endif
--- 649,654 ----
Index: cfgcleanup.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cfgcleanup.c,v
retrieving revision 1.73
diff -c -3 -p -r1.73 cfgcleanup.c
*** cfgcleanup.c	15 Feb 2003 21:06:16 -0000	1.73
--- cfgcleanup.c	21 Feb 2003 12:31:36 -0000
*************** delete_unreachable_blocks ()
*** 1751,1759 ****
  	  changed = true;
  	}
      }
- 
-   if (changed)
-     tidy_fallthru_edges ();
    return changed;
  }
  
--- 1751,1756 ----
Index: cfgrtl.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cfgrtl.c,v
retrieving revision 1.65
diff -c -3 -p -r1.65 cfgrtl.c
*** cfgrtl.c	21 Feb 2003 10:06:44 -0000	1.65
--- cfgrtl.c	21 Feb 2003 12:31:36 -0000
*************** tidy_fallthru_edge (e, b, c)
*** 1131,1178 ****
  
    e->flags |= EDGE_FALLTHRU;
  }
- 
- /* Fix up edges that now fall through, or rather should now fall through
-    but previously required a jump around now deleted blocks.  Simplify
-    the search by only examining blocks numerically adjacent, since this
-    is how find_basic_blocks created them.  */
- 
- void
- tidy_fallthru_edges ()
- {
-   basic_block b, c;
- 
-   if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
-     return;
- 
-   FOR_BB_BETWEEN (b, ENTRY_BLOCK_PTR->next_bb, EXIT_BLOCK_PTR->prev_bb, next_bb)
-     {
-       edge s;
- 
-       c = b->next_bb;
- 
-       /* We care about simple conditional or unconditional jumps with
- 	 a single successor.
- 
- 	 If we had a conditional branch to the next instruction when
- 	 find_basic_blocks was called, then there will only be one
- 	 out edge for the block which ended with the conditional
- 	 branch (since we do not create duplicate edges).
- 
- 	 Furthermore, the edge will be marked as a fallthru because we
- 	 merge the flags for the duplicate edges.  So we do not want to
- 	 check that the edge is not a FALLTHRU edge.  */
- 
-       if ((s = b->succ) != NULL
- 	  && ! (s->flags & EDGE_COMPLEX)
- 	  && s->succ_next == NULL
- 	  && s->dest == c
- 	  /* If the jump insn has side effects, we can't tidy the edge.  */
- 	  && (GET_CODE (b->end) != JUMP_INSN
- 	      || onlyjump_p (b->end)))
- 	tidy_fallthru_edge (s, b, c);
-     }
- }
  
  /* Helper function for split_edge.  Return true in case edge BB2 to BB1
     is back edge of syntactic loop.  */
--- 1131,1136 ----