--- /dev/null
+Hi,
+
+The attached patch makes sure that we create smaller object code for
+simple switch statements. We just make sure to flatten the switch
+statement into an if-else chain, basically.
+
+This fixes a size-regression as compared to gcc-3.4, as can be seen
+below.
+
+2007-04-15 Bernhard Fischer <..>
+
+ * stmt.c (expand_case): Do not create a complex binary tree when
+ optimizing for size but rather use the simple ordered list.
+ (emit_case_nodes): do not emit jumps to the default_label when
+ optimizing for size.
+
+Not regtested so far.
+Comments?
+
+Attached is the test switch.c mentioned below.
+
+$ 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
+gcc-$i -DCHAIN -Os -o switch-CHAIN-$i.o -c switch.c ;done
+$ 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
+gcc-$i -UCHAIN -Os -o switch-$i.o -c switch.c ;done
+
+$ size switch-*.o
+ text data bss dec hex filename
+ 169 0 0 169 a9 switch-2.95.o
+ 115 0 0 115 73 switch-3.3.o
+ 103 0 0 103 67 switch-3.4.o
+ 124 0 0 124 7c switch-4.0.o
+ 124 0 0 124 7c switch-4.1.o
+ 124 0 0 124 7c switch-4.2.orig-HEAD.o
+ 95 0 0 95 5f switch-4.3-HEAD.o
+ 124 0 0 124 7c switch-4.3.orig-HEAD.o
+ 166 0 0 166 a6 switch-CHAIN-2.95.o
+ 111 0 0 111 6f switch-CHAIN-3.3.o
+ 95 0 0 95 5f switch-CHAIN-3.4.o
+ 95 0 0 95 5f switch-CHAIN-4.0.o
+ 95 0 0 95 5f switch-CHAIN-4.1.o
+ 95 0 0 95 5f switch-CHAIN-4.2.orig-HEAD.o
+ 95 0 0 95 5f switch-CHAIN-4.3-HEAD.o
+ 95 0 0 95 5f switch-CHAIN-4.3.orig-HEAD.o
+
+
+Content-Type: text/x-diff; charset=us-ascii
+Content-Disposition: attachment; filename="gcc-4.3.gcc-flatten-switch-stmt.00.diff"
+
+Index: gcc-4.2.0/gcc/stmt.c
+===================================================================
+--- gcc-4.2.0.orig/gcc/stmt.c (revision 123843)
++++ gcc-4.2.0/gcc/stmt.c (working copy)
+@@ -2517,7 +2517,11 @@ expand_case (tree exp)
+ use_cost_table
+ = (TREE_CODE (orig_type) != ENUMERAL_TYPE
+ && estimate_case_costs (case_list));
+- balance_case_nodes (&case_list, NULL);
++ /* When optimizing for size, we want a straight list to avoid
++ jumps as much as possible. This basically creates an if-else
++ chain. */
++ if (!optimize_size)
++ balance_case_nodes (&case_list, NULL);
+ emit_case_nodes (index, case_list, default_label, index_type);
+ emit_jump (default_label);
+ }
+@@ -3075,6 +3079,7 @@ emit_case_nodes (rtx index, case_node_pt
+ {
+ if (!node_has_low_bound (node, index_type))
+ {
++ if (!optimize_size) /* don't jl to the .default_label. */
+ emit_cmp_and_jump_insns (index,
+ convert_modes
+ (mode, imode,
+
+
+Content-Type: text/x-csrc; charset=us-ascii
+Content-Disposition: attachment; filename="switch.c"
+
+int
+commutative_tree_code (int code)
+{
+#define CASE(val, ret) case val:/* __asm__("# val="#val ",ret="#ret);*/ return ret;
+#ifndef CHAIN
+ switch (code)
+ {
+# if 1
+ CASE(1,3)
+ CASE(3,2)
+ CASE(5,8)
+ CASE(7,1)
+ CASE(33,4)
+ CASE(44,9)
+ CASE(55,10)
+ CASE(66,-1)
+ CASE(77,99)
+ CASE(666,0)
+# else
+ case 1:
+ return 3;
+ case 3:
+ return 2;
+ case 5:
+ return 8;
+ case 7:
+ return 1;
+ case 33:
+ return 4;
+ case 44:
+ return 9;
+ case 55:
+ return 10;
+ case 66:
+ return -1;
+ case 77:
+ return 99;
+ case 666:
+ return 0;
+# endif
+ default:
+ break;
+ }
+ return 4711;
+
+#else
+ if (code == 1)
+ return 3;
+ else if (code == 3)
+ return 2;
+ else if (code == 5)
+ return 8;
+ else if (code == 7)
+ return 1;
+ else if (code == 33)
+ return 4;
+ else if (code == 44)
+ return 9;
+ else if (code == 55)
+ return 10;
+ else if (code == 66)
+ return -1;
+ else if (code == 77)
+ return 99;
+ else if (code == 666)
+ return 0;
+ else
+ return 4711;
+#endif
+}
+
+
+--AhhlLboLdkugWU4S--
+
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