This affects shared libraries on X86 32-bit. The linker stub doesn't restore the content of EAX. This may lead to corruption because dmd may pass an argument in EAX.
Comment #1 by code — 2013-05-31T11:52:36Z
Until now I don't know any solution other than to not use EAX for parameter passing. Maybe ECX or EDX would work as alternative.
Comment #2 by bugzilla — 2013-06-06T14:10:46Z
An example would be nice, please!
Comment #3 by code — 2013-06-06T15:14:37Z
cat > bug.d << CODE
import lib;
void main()
{
int val;
printf("%p\n", &val);
deref(&val) == 0 || assert(0);
}
CODE
cat > lib.d << CODE
extern(C) int printf(const char*, ...);
int deref(int* p)
{
printf("%p\n", p);
return *p;
}
CODE
dmd -g -m32 -fPIC -shared lib.d -ofliblib.so
dmd -g -m32 -fPIC bug.d -L-L. -L-llib -L-rpath=.
./bug
----
Oh, the above code actually works. It's not the PLT stub but the attached debugger (gdb-7.5.1) that trashes EAX. It only happens when stepping into a function called via PLT and I can only reproduce with emacs-GUD, probably because of some automatic variable update.
It also means there is another reason why phobos unittests crash on X86 :(.
Comment #4 by robert.schadek — 2024-12-13T18:07:14Z