diff options
Diffstat (limited to 'toolchain/gcc/patches/4.2.3/904-flatten-switch-stmt-00.patch')
| -rw-r--r-- | toolchain/gcc/patches/4.2.3/904-flatten-switch-stmt-00.patch | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/toolchain/gcc/patches/4.2.3/904-flatten-switch-stmt-00.patch b/toolchain/gcc/patches/4.2.3/904-flatten-switch-stmt-00.patch new file mode 100644 index 000000000..8fac37c4d --- /dev/null +++ b/toolchain/gcc/patches/4.2.3/904-flatten-switch-stmt-00.patch @@ -0,0 +1,153 @@ +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-- + |