Wert eines Defines merken und wiederherstellen

[Kas Ob.]

Hi,

There is few tricks can be used, but i can't find valuable for you in this case without affecting the performance for this performance critical procedure.

This is perfect workaround for 32bit but will not compile for 64 for the obvious reason

Code:

procedure AddC(var Value: UInt32; Add: UInt32; var Carry: Boolean);
begin
  Value := Value + Add;
  PByte(Value) := PByte(Value) + Ord(Add);
end;

Its assembly

Code:

Project5.dpr.15: Value := Value + Add;
0041A2BC 0110             add [eax],edx
0041A2BE 7305             jnb $0041a2c5
0041A2C0 E83FB3FEFF        call @IntOver
Project5.dpr.16: PByte(Value) := PByte(Value) + Ord(Add);
0041A2C5 0110             add [eax],edx
Project5.dpr.21: end;
0041A2C7 C3               ret

The overhead is one instruction in this case.

but all the other tricks and shenanigans that work for both platforms i can think of will introduce huge overhead instead of one or two instruction.
Like this one

Code:

procedure AddC(var Value: UInt32; Add: UInt32; var Carry: Boolean);
begin
  Value := Value + Add;
  Value := UInt32(PByte(Value) + Ord(Add));
end;

Generated code :

Code:

Project5.dpr.15: Value := Value + Add;
0041A2BC 0110             add [eax],edx
0041A2BE 7305             jnb $0041a2c5
0041A2C0 E83FB3FEFF        call @IntOver
Project5.dpr.16: Value := UInt32(PByte(Value) + Ord(Add));
0041A2C5 8B08             mov ecx,[eax]
0041A2C7 03CA              add ecx,edx
0041A2C9 8908             mov [eax],ecx
Project5.dpr.22: end;
0041A2CB C3               ret

Code:

Project5.dpr.15: Value := Value + Add;
00000000004261E8 0111             add [rcx],edx
00000000004261EA 7305             jnb AddC + $11
00000000004261EC E8AF12FEFF        call @IntOver
Project5.dpr.16: Value := UInt32(PByte(Value) + Ord(Add));
00000000004261F1 8B01             mov eax,[rcx]
00000000004261F3 8BD2             mov edx,edx
00000000004261F5 488D0410         lea rax,[rax+rdx]
00000000004261F9 8901             mov [rcx],eax
Project5.dpr.22: end;
00000000004261FB 488D6520         lea rsp,[rbp+$20]
00000000004261FF 5D                pop rbp
0000000000426200 C3               ret

We have stupid and outdated compiler !
Though the above result is on XE8, and i have no idea on how or will it even compile on newer versions.