|
The common case for this function is that both types are the same.
The Item_result defination from include/mysql.h.pp is the following enum
enum Item_result
|
{
|
STRING_RESULT=0, REAL_RESULT, INT_RESULT, ROW_RESULT, DECIMAL_RESULT,
|
TIME_RESULT
|
};
|
The compilers aren't quite smart enough to optimize to this shortcut so
this makes it quicker.
Before the change:
0000000000012730 <item_cmp_type(Item_result, Item_result)>:
|
12730: 89 f0 mov %esi,%eax
|
12732: 09 f8 or %edi,%eax
|
12734: 74 4c je 12782 <item_cmp_type(Item_result, Item_result)+0x52>
|
12736: 83 ff 02 cmp $0x2,%edi
|
12739: 75 0a jne 12745 <item_cmp_type(Item_result, Item_result)+0x15>
|
1273b: b8 02 00 00 00 mov $0x2,%eax
|
12740: 83 fe 02 cmp $0x2,%esi
|
12743: 74 3c je 12781 <item_cmp_type(Item_result, Item_result)+0x51>
|
12745: 83 ff 03 cmp $0x3,%edi
|
12748: b8 03 00 00 00 mov $0x3,%eax
|
1274d: 74 32 je 12781 <item_cmp_type(Item_result, Item_result)+0x51>
|
1274f: 83 fe 03 cmp $0x3,%esi
|
12752: 74 2d je 12781 <item_cmp_type(Item_result, Item_result)+0x51>
|
12754: 83 ff 05 cmp $0x5,%edi
|
12757: b8 05 00 00 00 mov $0x5,%eax
|
1275c: 74 23 je 12781 <item_cmp_type(Item_result, Item_result)+0x51>
|
1275e: 83 fe 05 cmp $0x5,%esi
|
12761: 74 1e je 12781 <item_cmp_type(Item_result, Item_result)+0x51>
|
12763: 83 ff 04 cmp $0x4,%edi
|
12766: 74 05 je 1276d <item_cmp_type(Item_result, Item_result)+0x3d>
|
12768: 83 ff 02 cmp $0x2,%edi
|
1276b: 75 0f jne 1277c <item_cmp_type(Item_result, Item_result)+0x4c>
|
1276d: b8 04 00 00 00 mov $0x4,%eax
|
12772: 83 fe 02 cmp $0x2,%esi
|
12775: 74 0a je 12781 <item_cmp_type(Item_result, Item_result)+0x51>
|
12777: 83 fe 04 cmp $0x4,%esi
|
1277a: 74 05 je 12781 <item_cmp_type(Item_result, Item_result)+0x51>
|
1277c: b8 01 00 00 00 mov $0x1,%eax
|
12781: c3 retq
|
12782: 31 c0 xor %eax,%eax
|
12784: c3 retq
|
After, noting the short cut and the beginning of the function:
0000000000012730 <item_cmp_type(Item_result, Item_result)>:
|
12730: 39 f7 cmp %esi,%edi
|
12732: 75 03 jne 12737 <item_cmp_type(Item_result, Item_result)+0x7>
|
12734: 89 f8 mov %edi,%eax
|
12736: c3 retq
|
12737: 83 ff 03 cmp $0x3,%edi
|
1273a: b8 03 00 00 00 mov $0x3,%eax
|
1273f: 74 32 je 12773 <item_cmp_type(Item_result, Item_result)+0x43>
|
12741: 83 fe 03 cmp $0x3,%esi
|
12744: 74 2d je 12773 <item_cmp_type(Item_result, Item_result)+0x43>
|
12746: 83 ff 05 cmp $0x5,%edi
|
12749: b8 05 00 00 00 mov $0x5,%eax
|
1274e: 74 23 je 12773 <item_cmp_type(Item_result, Item_result)+0x43>
|
12750: 83 fe 05 cmp $0x5,%esi
|
12753: 74 1e je 12773 <item_cmp_type(Item_result, Item_result)+0x43>
|
12755: 83 ff 04 cmp $0x4,%edi
|
12758: 74 05 je 1275f <item_cmp_type(Item_result, Item_result)+0x2f>
|
1275a: 83 ff 02 cmp $0x2,%edi
|
1275d: 75 0f jne 1276e <item_cmp_type(Item_result, Item_result)+0x3e>
|
1275f: b8 04 00 00 00 mov $0x4,%eax
|
12764: 83 fe 02 cmp $0x2,%esi
|
12767: 74 0a je 12773 <item_cmp_type(Item_result, Item_result)+0x43>
|
12769: 83 fe 04 cmp $0x4,%esi
|
1276c: 74 05 je 12773 <item_cmp_type(Item_result, Item_result)+0x43>
|
1276e: b8 01 00 00 00 mov $0x1,%eax
|
12773: c3 retq
|
|