Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Done
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10.3(EOL)
Description
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
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{
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STRING_RESULT=0, REAL_RESULT, INT_RESULT, ROW_RESULT, DECIMAL_RESULT,
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TIME_RESULT
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};
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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)>:
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12730: 89 f0 mov %esi,%eax
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12732: 09 f8 or %edi,%eax
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12734: 74 4c je 12782 <item_cmp_type(Item_result, Item_result)+0x52>
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12736: 83 ff 02 cmp $0x2,%edi
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12739: 75 0a jne 12745 <item_cmp_type(Item_result, Item_result)+0x15>
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1273b: b8 02 00 00 00 mov $0x2,%eax
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12740: 83 fe 02 cmp $0x2,%esi
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12743: 74 3c je 12781 <item_cmp_type(Item_result, Item_result)+0x51>
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12745: 83 ff 03 cmp $0x3,%edi
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12748: b8 03 00 00 00 mov $0x3,%eax
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1274d: 74 32 je 12781 <item_cmp_type(Item_result, Item_result)+0x51>
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1274f: 83 fe 03 cmp $0x3,%esi
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12752: 74 2d je 12781 <item_cmp_type(Item_result, Item_result)+0x51>
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12754: 83 ff 05 cmp $0x5,%edi
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12757: b8 05 00 00 00 mov $0x5,%eax
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1275c: 74 23 je 12781 <item_cmp_type(Item_result, Item_result)+0x51>
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1275e: 83 fe 05 cmp $0x5,%esi
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12761: 74 1e je 12781 <item_cmp_type(Item_result, Item_result)+0x51>
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12763: 83 ff 04 cmp $0x4,%edi
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12766: 74 05 je 1276d <item_cmp_type(Item_result, Item_result)+0x3d>
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12768: 83 ff 02 cmp $0x2,%edi
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1276b: 75 0f jne 1277c <item_cmp_type(Item_result, Item_result)+0x4c>
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1276d: b8 04 00 00 00 mov $0x4,%eax
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12772: 83 fe 02 cmp $0x2,%esi
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12775: 74 0a je 12781 <item_cmp_type(Item_result, Item_result)+0x51>
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12777: 83 fe 04 cmp $0x4,%esi
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1277a: 74 05 je 12781 <item_cmp_type(Item_result, Item_result)+0x51>
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1277c: b8 01 00 00 00 mov $0x1,%eax
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12781: c3 retq
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12782: 31 c0 xor %eax,%eax
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12784: c3 retq
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After, noting the short cut and the beginning of the function:
0000000000012730 <item_cmp_type(Item_result, Item_result)>:
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12730: 39 f7 cmp %esi,%edi
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12732: 75 03 jne 12737 <item_cmp_type(Item_result, Item_result)+0x7>
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12734: 89 f8 mov %edi,%eax
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12736: c3 retq
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12737: 83 ff 03 cmp $0x3,%edi
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1273a: b8 03 00 00 00 mov $0x3,%eax
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1273f: 74 32 je 12773 <item_cmp_type(Item_result, Item_result)+0x43>
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12741: 83 fe 03 cmp $0x3,%esi
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12744: 74 2d je 12773 <item_cmp_type(Item_result, Item_result)+0x43>
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12746: 83 ff 05 cmp $0x5,%edi
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12749: b8 05 00 00 00 mov $0x5,%eax
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1274e: 74 23 je 12773 <item_cmp_type(Item_result, Item_result)+0x43>
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12750: 83 fe 05 cmp $0x5,%esi
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12753: 74 1e je 12773 <item_cmp_type(Item_result, Item_result)+0x43>
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12755: 83 ff 04 cmp $0x4,%edi
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12758: 74 05 je 1275f <item_cmp_type(Item_result, Item_result)+0x2f>
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1275a: 83 ff 02 cmp $0x2,%edi
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1275d: 75 0f jne 1276e <item_cmp_type(Item_result, Item_result)+0x3e>
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1275f: b8 04 00 00 00 mov $0x4,%eax
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12764: 83 fe 02 cmp $0x2,%esi
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12767: 74 0a je 12773 <item_cmp_type(Item_result, Item_result)+0x43>
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12769: 83 fe 04 cmp $0x4,%esi
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1276c: 74 05 je 12773 <item_cmp_type(Item_result, Item_result)+0x43>
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1276e: b8 01 00 00 00 mov $0x1,%eax
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12773: c3 retq
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