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Asked: 2026-05-11T00:20:18+00:00

i wonder if i’ve found a compiler bug? i was removing some old code

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i wonder if i’ve found a compiler bug? i was removing some old code from my app and now i get stackoverflow at ‘begin’ (see code & disassembly below).

procedure TfraNewRTMDisplay.ShowMeasurement; var   iDummy, iDummy2, iDummy3:integer; begin    // STACK OVERFLOW BEFORE MY CODE STARTS   iDummy:=0;   iDummy2:=0;    case iDummy2 of     1:       case iDummy of         1:m_SelectedRTMMenuData.ChannelMeasSet.MeasKV.ClearMeasurementData;         2:m_SelectedRTMMenuData.ChannelMeasSet.MeasKV.ClearMeasurementData;       end;   end;   end;  NewRTMDisplay.pas.1601: begin 00983BF8 55               push ebp 00983BF9 8BEC             mov ebp,esp 00983BFB B9D4E40400       mov ecx,$0004e4d4 00983C00 6A00             push $00             // stack overflow loop 00983C02 6A00             push $00             // stack overflow loop  00983C04 49               dec ecx              // stack overflow loop   00983C05 75F9             jnz $00983c00        // stack overflow loop 00983C07 56               push esi 00983C08 57               push edi 00983C09 8945FC           mov [ebp-$04],eax 00983C0C 8D856005FFFF     lea eax,[ebp-$0000faa0] 00983C12 8B153C789A00     mov edx,[$009a783c] 00983C18 E88B35A8FF       call @InitializeRecord 00983C1D 8D85D00AFEFF     lea eax,[ebp-$0001f530] 00983C23 8B153C789A00     mov edx,[$009a783c] 00983C29 E87A35A8FF       call @InitializeRecord 00983C2E 33C0             xor eax,eax 00983C30 55               push ebp 00983C31 68F73C9800       push $00983cf7 00983C36 64FF30           push dword ptr fs:[eax] 00983C39 648920           mov fs:[eax],esp NewRTMDisplay.pas.1602: iDummy:=0; 00983C3C 33C0             xor eax,eax 00983C3E 8945F8           mov [ebp-$08],eax NewRTMDisplay.pas.1603: iDummy2:=0; 00983C41 33C0             xor eax,eax 00983C43 8945F4           mov [ebp-$0c],eax NewRTMDisplay.pas.1605: case iDummy2 of 00983C46 8B45F4           mov eax,[ebp-$0c] 00983C49 48               dec eax 00983C4A 7571             jnz $00983cbd NewRTMDisplay.pas.1607: case iDummy of 00983C4C 8B45F8           mov eax,[ebp-$08] 00983C4F 48               dec eax 00983C50 7405             jz $00983c57 00983C52 48               dec eax 00983C53 7436             jz $00983c8b 00983C55 EB66             jmp $00983cbd NewRTMDisplay.pas.1608: 1:m_SelectedRTMMenuData.ChannelMeasSet.MeasKV.ClearMeasurementData; 00983C57 8D951872EBFF     lea edx,[ebp-$00148de8] 00983C5D 8B45FC           mov eax,[ebp-$04] 00983C60 8B80F0020000     mov eax,[eax+$000002f0] 00983C66 E895DBE9FF       call TRTMMenuData.ChannelMeasSet 00983C6B 8DB52072EBFF     lea esi,[ebp-$00148de0] 00983C71 8DBD6005FFFF     lea edi,[ebp-$0000faa0] 00983C77 B9A43E0000       mov ecx,$00003ea4 00983C7C F3A5             rep movsd  00983C7E 8D856005FFFF     lea eax,[ebp-$0000faa0] 00983C84 E81B3F0200       call TDeviceMeas.ClearMeasurementData 00983C89 EB32             jmp $00983cbd NewRTMDisplay.pas.1609: 2:m_SelectedRTMMenuData.ChannelMeasSet.MeasKV.ClearMeasurementData; 00983C8B 8D9560D9D8FF     lea edx,[ebp-$002726a0] 00983C91 8B45FC           mov eax,[ebp-$04] 00983C94 8B80F0020000     mov eax,[eax+$000002f0] 00983C9A E861DBE9FF       call TRTMMenuData.ChannelMeasSet 00983C9F 8DB568D9D8FF     lea esi,[ebp-$00272698] 00983CA5 8DBDD00AFEFF     lea edi,[ebp-$0001f530] 00983CAB B9A43E0000       mov ecx,$00003ea4 00983CB0 F3A5             rep movsd  00983CB2 8D85D00AFEFF     lea eax,[ebp-$0001f530] 00983CB8 E8E73E0200       call TDeviceMeas.ClearMeasurementData NewRTMDisplay.pas.1612: end;

any ideas?

thank you! mp

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1 Answer

  1. Yuliy is right: The 320KB buffer is likely an array[20] of whatever is returned by ChannelMeasSet – based on the size of the rep movsd loop.

    It looks like you’ve got some code that is returning a very large data structure by value, rather than just a reference to it. Apart from the stack overflow issue, that’s likely to be very inefficient.

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