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Re: AMD64 ABI compatibility


Thanks for your reply. The gcc compiler uses %rdi, %rsi, %rdx, %rcx with -mregparm=4, but MS uses %rcx, %rdx, %r8, %r9, so that won't be enough. Also MS requires some space on the stack to be reserved for the 4 regs.

Someone has written a wrapper:
http://people.freebsd.org/~wpaul/winx64_wrap.S


On Jul 9, 2007, at 12:58 , Dave Korn wrote:


On 09 July 2007 20:48, Nicolas Alt wrote:

Hi!

On the AMD64 / x86-64Bit architecture, some arguments of a functions
are passed using registers, but there seem to be two different
conventions out there. The standard ABI uses 6 registers, but
Microsoft compilers use only 4. Because of that, code compiled with
gcc cannot call code compiled with a MS compiler without an ugly
wrapper.

Have there been any efforts to make gcc do function calls the MS way?
I guess this would be an important feature for mingw on AMD64.


Does -mregparm=4 do what you want?


cheers, DaveK -- Can't think of a witty .sigline today....



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