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diff --git a/meta/packages/gcc/gcc-4.2.3/904-flatten-switch-stmt-00.patch b/meta/packages/gcc/gcc-4.2.3/904-flatten-switch-stmt-00.patch
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1Hi,
2
3The attached patch makes sure that we create smaller object code for
4simple switch statements. We just make sure to flatten the switch
5statement into an if-else chain, basically.
6
7This fixes a size-regression as compared to gcc-3.4, as can be seen
8below.
9
102007-04-15 Bernhard Fischer <..>
11
12 * stmt.c (expand_case): Do not create a complex binary tree when
13 optimizing for size but rather use the simple ordered list.
14 (emit_case_nodes): do not emit jumps to the default_label when
15 optimizing for size.
16
17Not regtested so far.
18Comments?
19
20Attached is the test switch.c mentioned below.
21
22$ 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
23gcc-$i -DCHAIN -Os -o switch-CHAIN-$i.o -c switch.c ;done
24$ 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
25gcc-$i -UCHAIN -Os -o switch-$i.o -c switch.c ;done
26
27$ size switch-*.o
28 text data bss dec hex filename
29 169 0 0 169 a9 switch-2.95.o
30 115 0 0 115 73 switch-3.3.o
31 103 0 0 103 67 switch-3.4.o
32 124 0 0 124 7c switch-4.0.o
33 124 0 0 124 7c switch-4.1.o
34 124 0 0 124 7c switch-4.2.orig-HEAD.o
35 95 0 0 95 5f switch-4.3-HEAD.o
36 124 0 0 124 7c switch-4.3.orig-HEAD.o
37 166 0 0 166 a6 switch-CHAIN-2.95.o
38 111 0 0 111 6f switch-CHAIN-3.3.o
39 95 0 0 95 5f switch-CHAIN-3.4.o
40 95 0 0 95 5f switch-CHAIN-4.0.o
41 95 0 0 95 5f switch-CHAIN-4.1.o
42 95 0 0 95 5f switch-CHAIN-4.2.orig-HEAD.o
43 95 0 0 95 5f switch-CHAIN-4.3-HEAD.o
44 95 0 0 95 5f switch-CHAIN-4.3.orig-HEAD.o
45
46
47Content-Type: text/x-diff; charset=us-ascii
48Content-Disposition: attachment; filename="gcc-4.3.gcc-flatten-switch-stmt.00.diff"
49
50Index: gcc-4.2.0/gcc/stmt.c
51===================================================================
52--- gcc-4.2.0.orig/gcc/stmt.c (revision 123843)
53+++ gcc-4.2.0/gcc/stmt.c (working copy)
54@@ -2517,7 +2517,11 @@ expand_case (tree exp)
55 use_cost_table
56 = (TREE_CODE (orig_type) != ENUMERAL_TYPE
57 && estimate_case_costs (case_list));
58- balance_case_nodes (&case_list, NULL);
59+ /* When optimizing for size, we want a straight list to avoid
60+ jumps as much as possible. This basically creates an if-else
61+ chain. */
62+ if (!optimize_size)
63+ balance_case_nodes (&case_list, NULL);
64 emit_case_nodes (index, case_list, default_label, index_type);
65 emit_jump (default_label);
66 }
67@@ -3075,6 +3079,7 @@ emit_case_nodes (rtx index, case_node_pt
68 {
69 if (!node_has_low_bound (node, index_type))
70 {
71+ if (!optimize_size) /* don't jl to the .default_label. */
72 emit_cmp_and_jump_insns (index,
73 convert_modes
74 (mode, imode,
75
76
77Content-Type: text/x-csrc; charset=us-ascii
78Content-Disposition: attachment; filename="switch.c"
79
80int
81commutative_tree_code (int code)
82{
83#define CASE(val, ret) case val:/* __asm__("# val="#val ",ret="#ret);*/ return ret;
84#ifndef CHAIN
85 switch (code)
86 {
87# if 1
88 CASE(1,3)
89 CASE(3,2)
90 CASE(5,8)
91 CASE(7,1)
92 CASE(33,4)
93 CASE(44,9)
94 CASE(55,10)
95 CASE(66,-1)
96 CASE(77,99)
97 CASE(666,0)
98# else
99 case 1:
100 return 3;
101 case 3:
102 return 2;
103 case 5:
104 return 8;
105 case 7:
106 return 1;
107 case 33:
108 return 4;
109 case 44:
110 return 9;
111 case 55:
112 return 10;
113 case 66:
114 return -1;
115 case 77:
116 return 99;
117 case 666:
118 return 0;
119# endif
120 default:
121 break;
122 }
123 return 4711;
124
125#else
126 if (code == 1)
127 return 3;
128 else if (code == 3)
129 return 2;
130 else if (code == 5)
131 return 8;
132 else if (code == 7)
133 return 1;
134 else if (code == 33)
135 return 4;
136 else if (code == 44)
137 return 9;
138 else if (code == 55)
139 return 10;
140 else if (code == 66)
141 return -1;
142 else if (code == 77)
143 return 99;
144 else if (code == 666)
145 return 0;
146 else
147 return 4711;
148#endif
149}
150
151
152--AhhlLboLdkugWU4S--
153