Hi,
Checking the llvm test-suite with latest clang/lld I noticed some regressions
on both x86_64 and aarch64. Tracking down I found it is due 'ldd' not being
handling correct the init_array segments for some cases.
For instance the code:
global_ctor.cpp:
#include <stdio.h>
//extern int printf(const char *, ...);
int CN = 0;
int DN = 0;
struct foo {
int Num;
foo(int num) : Num(num) {
printf("Foo ctor %d %d\n", Num, CN++);
}
~foo() {
printf("Foo dtor %d %d\n", Num, DN++);
}
} Constructor1(7); // Global with ctor to be called before main
foo Constructor2(12);
struct bar {
~bar() {
printf("bar dtor\n");
}
} Destructor1; // Global with dtor
int main() {
printf("main\n");
return 0;
}
GCC 4.9 generates:
Section Headers:
[...]
[15] .init_array INIT_ARRAY 0000000000000000 000001c0
0000000000000008 0000000000000000 WA 0 0 8
[...]
Symbol table '.symtab' contains 37 entries:
[...]
11: 0000000000000000 0 SECTION LOCAL DEFAULT 15
[...]
While clang (trunk):
[...]
[18] .init_array INIT_ARRAY 0000000000000000 00000270
0000000000000008 0000000000000000 WA 0 0 8
[...]
Main difference is clang is not adding the init_array symbol in .symtab. This
makes ldd ignore the object section in ELFFile<ELFT>::createSymbolsFromAtomizableSections
and thus not updating the init_array in final executable with object's init_array
(and not triggering the object constructors).
Now, the question is if this is a clang regression (since the test-suite was not
failing two weeks ago), or it is something ldd should handle (since ld/gold handles
it correctly). Also for 'ldd' which would be best strategy to handle such case:
create a empty section atom (createSectionAtom(...)) if some 'runtime' segments
are present (init_array, etc.)?