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http://sourceware.org/bugzilla/show_bug.cgi?id=15559 Bug ID: 15559 Summary: Method call and calling convention Product: gdb Version: 7.6 Status: NEW Severity: normal Priority: P2 Component: c++ Assignee: unassigned at sourceware dot org Reporter: kifathegreat at gmail dot com Hello! I have faced a problem using GDB(7.5, 7.6) with GCC 4.8.0 x86 on Ubuntu 12.04 and Windows XP. Here is the issue description. GDB has commands to call function from the program being debugged. They are print and call. But unfortunately the mentioned above commands work incorrectly for class methods with __thiscall calling convention. Windows x86 targets are using the __thiscall calling convention for C++ class-member functions by default from GCC 4.7. Judging by command return values GDB does not set object address (this pointer) to ECX registry before method call. So these commands trigger for some object only if last executed line of the program being debugged contains method call for the same object. In this case ECX registry will contain necessary address (this pointer). For methods with __cdecl calling convention print (call) works perfectly. Thanks, Kifa C++ program Test: 01:#include <iostream> 02:class Test 03:{ 04: public: 05: Test(int value) : _value(value) {} 06: int value() const __attribute__((thiscall)) { return _value; } 07: private: 08: int _value; 09:}; 10:int main() 11:{ 12: Test test1(123); 13: Test test2(456); 14: int value1 = test1.value(); 15: int value2 = test2.value(); 16: std::cout << value1 + value2 << std::endl; 17: return 0; 18:} GDB session: GNU gdb (GDB) 7.5.1-ubuntu Copyright (C) 2012 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "x86_64-linux-gnu". For bug reporting instructions, please see: <http://www.gnu.org/software/gdb/bugs/>. (gdb) file Test Reading symbols from /home/kifa/QtCreator/_Test_gcc4.8/Debug/Test...done. (gdb) break main Breakpoint 1 at 0x80487fd: file /home/kifa/QtCreator/Test/main.cpp, line 12. (gdb) run Starting program: /home/kifa/QtCreator/_Test_gcc4.8/Debug/Test Breakpoint 1, main () at /home/kifa/QtCreator/Test/main.cpp:12 12 Test test1(123); (gdb) next 13 Test test2(456); (gdb) print test1.value() $1 = -11264 (gdb) next 14 int value1 = test1.value(); (gdb) print test1.value() $2 = -11264 (gdb) next 15 int value2 = test2.value(); (gdb) print test1.value() $3 = 123 (gdb) next 16 std::cout << value1 + value2 << std::endl; (gdb) print test1.value() $4 = 456 (gdb) next 579 17 return 0; (gdb) print test1.value() $5 = 0 (gdb) continue Continuing. [Inferior 1 (process 4180) exited normally] (gdb) -- You are receiving this mail because: You are on the CC list for the bug.
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