I don't currently have many details. (The code in question has been
working on older 3.3.1, and still works on 3.2.3 and before)
I included various details, but in the end it may be a peephole issues
in "GetInterfaceByStr"
==> So probably skip ahead to the asm code below.
The code call a method expecting an interface, and providing an instance
as param. The instance is of a class implementing the interface.
The class uses generics as base, including generics (for the interface)
for the expected param in the called method.
I tested with O2 and O4 (for my code )
===> and for fpc/rtl: -CX -gl -gw3 -O-1
rev e84e0a16e13a4b73192edafd2aa356254dc2ac88
The line that fails is:
function TObject.GetInterfaceByStr(const iidstr : shortstring;out
obj) : boolean;
...
if result and Assigned(IEntry^.IID) and (IEntry^.IType in
[etStandard, etFieldValue]) then
IInterface(obj)._AddRef;
At the time
Result = true
IEntry^ =
( IIDREF: ^PGUID(nil);
VTABLE: $0000000100719838^: ;
IOFFSET: 32;
IOFFSETASCODEPTR: $0000000000000020^: ;
IIDSTRREF: $00000001007103E8^^: $00000001007103E0^: '';
ITYPE: ETSTANDARD)
IEntry^.IID gets
function tinterfaceentry.GetIID: pguid;
begin
if Assigned(IIDRef) then
GetIID:=IIDRef^
else
GetIID:=Nil;
The interface for the param is "CORBA". (so IIDRef should be nil,
according to comments in the code)
Generated asm (as reported by GDB) / Crash line is marked <<<<<<<<<<<<<
=> Something seems strange. There is a "cmp" without any conditional
after it?
..\inc\objpas.inc:922
0000000100012293 807de400 cmpb $0x0,-0x1c(%rbp)
0000000100012297 7441 je 0x1000122da
<GETINTERFACEBYSTR+170>
0000000100012299 488b45d8 mov
-0x28(%rbp),%rax // EAX = The address pointing to IEntry
..\inc\objpas.inc:924
000000010001229D 31c9 xor %ecx,%ecx
..\inc\objpas.inc:922
000000010001229F 48833800 cmpq $0x0,(%rax)
00000001000122A3 488b00 mov (%rax),%rax // EAX =
The first qword in the record. That is RAX = IEntry^.IIDRef
00000001000122A6 488b00 mov (%rax),%rax //
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< RAX = 0x0
00000001000122A9 488b45d8 mov -0x28(%rbp),%rax
00000001000122AD 480f44c1 cmove %rcx,%rax
00000001000122B1 4885c0 test %rax,%rax
00000001000122B4 7424 je 0x1000122da
<GETINTERFACEBYSTR+170>
00000001000122B6 488b45d8 mov -0x28(%rbp),%rax
00000001000122BA 8b4020 mov 0x20(%rax),%eax
00000001000122BD 85c0 test %eax,%eax
00000001000122BF 7405 je 0x1000122c6
<GETINTERFACEBYSTR+150>
00000001000122C1 83f803 cmp $0x3,%eax
00000001000122C4 7514 jne 0x1000122da
<GETINTERFACEBYSTR+170>
..\inc\objpas.inc:923
#0 TOBJECT.GETINTERFACEBYSTR(TOBJECT($000000000CF471C0), '', 0) at
c:\FPC\fpc_3.3.1\source\rtl\inc\objpas.inc:922
#1 TOBJECT.GETINTERFACE(TOBJECT($000000000CF471C0), '', 0) at
c:\FPC\fpc_3.3.1\source\rtl\inc\objpas.inc:928
#2 fpc_class_as_corbaintf(POINTER($000000000CF471C0), '') at
c:\FPC\fpc_3.3.1\source\rtl\inc\objpas.inc:262
#3
TINTERNALDBGMONITORBASE$3$CRC97C7D6C3_CRC46A2B365.SETSUPPLIER(TINTERNALDBGMONITORBASE$3$CRC97C7D6C3_CRC46A2B365($000000000CF471C0),
Failed to read data from register) at lazdebuggertemplate.pas:112
#4
TTESTDBGDEBUGGER.INITDEBUGGERMONITORS(TTESTDBGDEBUGGER($000000000CF471C0),
Failed to read data from register) at
B:\lazarus_main\components\lazdebuggers\lazdebugtestbase\ttestdbgexecuteables.pas:399
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