add gcc 4.2.1
[openwrt/openwrt.git] / toolchain / gcc / patches / 4.2.1 / 904-flatten-switch-stmt-00.patch
1 Hi,
2
3 The attached patch makes sure that we create smaller object code for
4 simple switch statements. We just make sure to flatten the switch
5 statement into an if-else chain, basically.
6
7 This fixes a size-regression as compared to gcc-3.4, as can be seen
8 below.
9
10 2007-04-15 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
17 Not regtested so far.
18 Comments?
19
20 Attached 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
23 gcc-$i -DCHAIN -Os -o switch-CHAIN-$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
25 gcc-$i -UCHAIN -Os -o switch-$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
47 Content-Type: text/x-diff; charset=us-ascii
48 Content-Disposition: attachment; filename="gcc-4.3.gcc-flatten-switch-stmt.00.diff"
49
50 Index: 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
77 Content-Type: text/x-csrc; charset=us-ascii
78 Content-Disposition: attachment; filename="switch.c"
79
80 int
81 commutative_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