#include <stdio.h> #include <stdlib.h>class Node{ public: int a; int b; }; extern "C" void demoNew(void) { Node *n0 = new Node; Node *n1 = (Node *)new char[sizeof(Node)]; printf("no=%p n1=%p\n", n0, n1); delete n0; delete[] n1; } int main(int argc, char ** argv) { demoNew(); return 0; }
--4747-- REDIR: 0x4d9b924 (libc.so:operator new[](unsigned long)) redirected to 0x4c1bb48 (operator new[](unsigned long))
--4747-- REDIR: 0x4d9b8d8 (libc.so:operator new(unsigned long)) redirected to 0x4c1b7a4 (operator new(unsigned long))
Well, it is puzzling why 'operator new[]' and 'operator new' are in libc.so, the run-time library for *plain*-C. The C language does not have such functions.
--4747-- REDIR: 0x4b44a60 (libc++.so:operator delete[](void*)) redirected to 0x4c1c3c4 (operator delete[](void*))
OK, that's the regular 'operator delete[]' for C++. Where is 'operator delete', the non-array flavor?
==4747== Mismatched free() / delete / delete [] ==4747== at 0x4C1C44C: operator delete[](void*) (vg_replace_malloc.c:620) ==4747== by 0x108797: demoNew (testNew.cpp:15) ==4747== by 0x108797: main (testNew.cpp:20) ==4747== Address 0x4eb9d70 is 0 bytes inside a block of size 8 alloc'd ==4747== at 0x4C1B1F0: malloc (vg_replace_malloc.c:298) ==4747== by 0x4B56CAF: operator new(unsigned long) (stdlib_new_delete.cpp:33)
That reference above to 'operator new(unsigned long)' should have been intercepted directly by valgrind, instead of first calling malloc() [which was intercepted.] Valgrind does not know about "stdlib_new_delete.cpp". Which shared library is it in?
==4747== by 0x10876F: demoNew (testNew.cpp:12) ==4747== by 0x10876F: main (testNew.cpp:20) localhost:/system/bin # nm -C ../lib64/libc.so | grep new
00000000000b2924 t operator new[](unsigned long) 00000000000b28d8 t operator new(unsigned long)
Again, I don't understand why libc.so has those functions. Does it have also the corresponding 'delete' and 'delete[]'?
localhost:/system/bin # nm -C ../lib64/libc++.so | grep new 000000000005cd1c W operator new[](unsigned long) 000000000005cc8c W operator new(unsigned long)
My working hypothesis is that appearance in libc.so of the code for some C++ operators, instead of appearing only in libc++.so, has confused valgrind. Also note that the C++ 'operator new' is a 'W' (weak global) symbol, but the plain-C symbol 'operator new' is a 't' (strong local) symbol. A local symbol is not exported, so it is visible only to calls from the same source file. On the other hand, a weak symbol becomes hidden if there is any [visible] strong definition. This is very confusing. ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Valgrind-users mailing list Valgrind-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/valgrind-users
