Values for vmtArcOffset and CPP_ABI_ADJUST

[dummzeuch 1389]

I need the values for the constants vmtArcOffset and CPP_ABI_ADJUST (declared in the System unit) for various platforms. I know them for

• Win32  (both 0)
• Win64 (0 and 24 = 3*SizeOf(Pointer64))
• Android32 (0 and 12 = 3*SizeOf(Pointer32))
• Android64 (0 and 24 = 3*SizeOf(Pointer64))
• IOS64 (0 and 24 = 3*SizeOf(Pointer64))
• OSX64 (0 and 24 = 3*SizeOf(Pointer64))

Could somebody who develops for other platforms please look them up and tell me?

• IOS32
• OSX32
• Linux

 

I'm not sure about the vmtArcOffset and how it changed for different platforms when Embarcadero introduced and when they later dropped ARC support. the automatic reference counting ARC support supposedly sets vmtArcOffset = 2 * SizeOf(Pointer).

[Uwe Raabe 1879]

Well, in System.pas from 10.4.1 they are declared like this:

 

{$IFDEF AUTOREFCOUNT}
  vmtArcOffset    = 2 * SizeOf(Pointer);
{$ELSE}
  vmtArcOffset    = 0;
{$ENDIF}

{$IFDEF CPP_ABI_SUPPORT}
  CPP_ABI_ADJUST = 3 * SizeOf(Pointer);
{$ELSE !CPP_ABI_SUPPORT}
  CPP_ABI_ADJUST = 0;
{$ENDIF !CPP_ABI_SUPPORT}

 

[dummzeuch 1389]

17 minutes ago, Uwe Raabe said:

Well, in System.pas from 10.4.1 they are declared like this:

 

{$IFDEF AUTOREFCOUNT}
  vmtArcOffset    = 2 * SizeOf(Pointer);
{$ELSE}
  vmtArcOffset    = 0;
{$ENDIF}

{$IFDEF CPP_ABI_SUPPORT}
  CPP_ABI_ADJUST = 3 * SizeOf(Pointer);
{$ELSE !CPP_ABI_SUPPORT}
  CPP_ABI_ADJUST = 0;
{$ENDIF !CPP_ABI_SUPPORT}

 

Yes, I know, that's where I got those constant names from, but I don't know for which platform which symbol is defined.

[dummzeuch 1389]

I found an easier solution: I'm now using IOTAThread.Evaluate to get the values of these constants (actually I needed vmtParent and vmtClassName which I originally wanted to calculate like the RTL does). Seems to work and doesn't even require me to know the target platform.