mirror of
git://projects.qi-hardware.com/openwrt-xburst.git
synced 2024-08-22 02:27:09 +03:00
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@7753 3c298f89-4303-0410-b956-a3cf2f4a3e73
154 lines
4.0 KiB
Diff
154 lines
4.0 KiB
Diff
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--
|
|
|