Hi, On Wed, 11 Oct 2006, Kai Tietz wrote:
> > -mcmodel=small' > > Generate code for the small code model: the program and its > > symbols must be linked in the lower 2 GB of the address space. > > Pointers are 64 bits. Programs can be statically or dynamically > > linked. This is the default code model. > > You are right, the documentation I read, too. But as described even for > the small-model pointers are 64-bit and are treated beside the argument > passing via register correctly. The problem is that a function just set > the lower 32-bit of the register, but the method using this register as > argument uses the 64-bit register variant, which means the upper 32-bit of > the register have random values.. No. The x86-64 instructions which set a 32bit register implicitely zero out the upper 32bit. This is in difference to those operating on the 16 or 8bit parts, which leave the upper parts untouched. So this code actually sets $rcx to [0, (uint32)&.LC0] As you are compiling for the small model it's required that &.LC0 == (uint32)&.LC0, because it's static data. And yes, this means that small code model executables have to have a base address < 2GB. This is in difference to the small PIC model, where the overall range of all static program addresses must be < 2GB. Ciao, Michael.
