On 2/15/2018 3:01 PM, Dibyendu Majumdar wrote:
Don't forget Agner Fog (I guess he's more familiar to older folks), see the doc on calling conventions:On 15 February 2018 at 06:40, Thomas Buergel wrote:Looks like there was a bug in luaffi when passing parameters to functions on the stack on x86-64 platform. I have not found definitive documentation clarifying this (if anyone can provide a reference that would be very helpful) but it seems that stack arguments must be at 8 byte boundaries.The two dominant x86-64 calling conventions in an overview: https://en.wikipedia.org/wiki/X86_calling_conventions#x86-64_calling_conventions For once, the one used on Windows is simpler: https://docs.microsoft.com/en-us/cpp/build/calling-convention Especially varargs can be a challenge on the SysV x86-64 ABI: https://blog.nelhage.com/2010/10/amd64-and-va_arg/Thank you - I was aware of the first two references but there doesn't seem to be a discussion on the requirements of size/alignment of arguments passed on the stack. I found following: https://stackoverflow.com/questions/32614007/size-and-alignment-of-x64-stack-arguments And: http://refspecs.linuxfoundation.org/elf/x86_64-abi-0.99.pdf Above says: The size of each argument gets rounded up to eightbytes
http://www.agner.org/optimize/ -- Cheers, Kein-Hong Man (esq.) Selangor, Malaysia