yann@552: Original patch from gentoo: gentoo/src/patchsets/gcc/4.3.0/gentoo/18_all_904-flatten-switch-stmt-00.patch
yann@552: http://gcc.gnu.org/ml/gcc-patches/2007-04/msg00927.html
yann@552: 
yann@552: Hi,
yann@552: 
yann@552: The attached patch makes sure that we create smaller object code for
yann@552: simple switch statements. We just make sure to flatten the switch
yann@552: statement into an if-else chain, basically.
yann@552: 
yann@552: This fixes a size-regression as compared to gcc-3.4, as can be seen
yann@552: below.
yann@552: 
yann@552: 2007-04-15  Bernhard Fischer  <..>
yann@552: 
yann@552: 	* stmt.c (expand_case): Do not create a complex binary tree when
yann@552: 	optimizing for size but rather use the simple ordered list.
yann@552: 	(emit_case_nodes): do not emit jumps to the default_label when
yann@552: 	optimizing for size.
yann@552: 
yann@552: Not regtested so far.
yann@552: Comments?
yann@552: 
yann@552: Attached is the test switch.c mentioned below.
yann@552: 
yann@552: $ for i in 2.95 3.3 3.4 4.0 4.1 4.2.orig-HEAD 4.3.orig-HEAD 4.3-HEAD;do
yann@552: gcc-$i  -DCHAIN -Os -o switch-CHAIN-$i.o -c switch.c ;done
yann@552: $ for i in 2.95 3.3 3.4 4.0 4.1 4.2.orig-HEAD 4.3.orig-HEAD 4.3-HEAD;do
yann@552: gcc-$i  -UCHAIN -Os -o switch-$i.o -c switch.c ;done
yann@552: 
yann@552: $ size switch-*.o
yann@552:    text	   data	    bss	    dec	    hex	filename
yann@552:     169	      0	      0	    169	     a9	switch-2.95.o
yann@552:     115	      0	      0	    115	     73	switch-3.3.o
yann@552:     103	      0	      0	    103	     67	switch-3.4.o
yann@552:     124	      0	      0	    124	     7c	switch-4.0.o
yann@552:     124	      0	      0	    124	     7c	switch-4.1.o
yann@552:     124	      0	      0	    124	     7c	switch-4.2.orig-HEAD.o
yann@552:      95	      0	      0	     95	     5f	switch-4.3-HEAD.o
yann@552:     124	      0	      0	    124	     7c	switch-4.3.orig-HEAD.o
yann@552:     166	      0	      0	    166	     a6	switch-CHAIN-2.95.o
yann@552:     111	      0	      0	    111	     6f	switch-CHAIN-3.3.o
yann@552:      95	      0	      0	     95	     5f	switch-CHAIN-3.4.o
yann@552:      95	      0	      0	     95	     5f	switch-CHAIN-4.0.o
yann@552:      95	      0	      0	     95	     5f	switch-CHAIN-4.1.o
yann@552:      95	      0	      0	     95	     5f	switch-CHAIN-4.2.orig-HEAD.o
yann@552:      95	      0	      0	     95	     5f	switch-CHAIN-4.3-HEAD.o
yann@552:      95	      0	      0	     95	     5f	switch-CHAIN-4.3.orig-HEAD.o
yann@552: 
yann@552: 
yann@552: Content-Type: text/x-diff; charset=us-ascii
yann@552: Content-Disposition: attachment; filename="gcc-4.3.gcc-flatten-switch-stmt.00.diff"
yann@552: 
yann@552: diff -durN gcc-4.3.0.orig/gcc/stmt.c gcc-4.3.0/gcc/stmt.c
yann@552: --- gcc-4.3.0.orig/gcc/stmt.c	2007-12-04 22:55:32.000000000 +0100
yann@552: +++ gcc-4.3.0/gcc/stmt.c	2008-06-10 14:44:33.000000000 +0200
yann@552: @@ -2508,7 +2508,11 @@
yann@552:  	  use_cost_table
yann@552:  	    = (TREE_CODE (orig_type) != ENUMERAL_TYPE
yann@552:  	       && estimate_case_costs (case_list));
yann@552: -	  balance_case_nodes (&case_list, NULL);
yann@552: +	  /* When optimizing for size, we want a straight list to avoid
yann@552: +	     jumps as much as possible. This basically creates an if-else
yann@552: +	     chain.  */
yann@552: +	  if (!optimize_size)
yann@552: +	    balance_case_nodes (&case_list, NULL);
yann@552:  	  emit_case_nodes (index, case_list, default_label, index_type);
yann@552:  	  emit_jump (default_label);
yann@552:  	}
yann@552: @@ -3066,6 +3070,7 @@
yann@552:  	    {
yann@552:  	      if (!node_has_low_bound (node, index_type))
yann@552:  		{
yann@552: +		  if (!optimize_size) /* don't jl to the .default_label. */
yann@552:  		  emit_cmp_and_jump_insns (index,
yann@552:  					   convert_modes
yann@552:  					   (mode, imode,