Hello,
I've been working on the PPC64-port for the Linux on Power contest for some time now, and finally have some questions I'd like to ask for here:
Some introduction: I am trying to use the PPC64-ELF ABI for all generated methods, first because of compatibility issues (I believe it's needed anyway) and it imo does not really matter which to choose initially.
There are two problems with that though; I didn't fix them yet because I'm hesitating to change stuff in the compiler-directory (all ppc64 specific things are in a subdirectory at the moment), and that's why I'm asking:
*) functions are not simple adresses anymore, but references to a so called function descriptor (if I remember the name correctly). Problem is that the assembly generator seems to hardcode the method specification prologue to:
.globl <mangledmethodname> .type <mangledmethodname>, @function <mangledmethodname>: ... method assembly ...
Problem is that this does not seem to work on PPC64 (tried on some hand-made assembly code); the GNU linker assumes that <mangledmethodname> is a function pointer, mangles it, and the resulting programs always crash on calling a method... ;-)
I found that in aggas.pas this behaviour seems to be hardcoded. Is there another way to change the function specification prologue?
(Btw, there's a similar problem with the epilogue)
There is a way to specify "local" methods without those function pointers, but... this works for local methods only. :(
*) as far as I understand PPC64 ELF ABI assumes that at if there's a stack, the area which holds the register contents R3-R10 is always available (e.g. the 8x8 bytes for saving register contents). Is there a way to specify a minimum size for the stack without changing something in the method which calculates stack layout?
(I thought of something like dummy local variables if needed)
*) How do I add a symbol/constant to the TOC? I'd like to avoid certain really time consuming operations on constants...
*) one really minor thing: what should the platform be called? PPC64? POWERPC64? POWERPC_64 (like x86_64)? =)
Finally I've got some more general question on the challenge:
What does "must be optimized for 64-bit platforms" in the challenge details mean?
In the same sense I'd like to ask if you could specify some sort of minimum requirements for the port in a little more detail?
(E.g. must cycle using the makefiles, must integrate into fpc distro, must compile + run IDE, must successfully run x tests, etc..., whatever)
Regards, Thomas
_______________________________________________ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
