4 Jan
2016
4 Jan
'16
5:35 p.m.
scj(a)yaccman.com <scj(a)yaccman.com> wrote:
As part of the PCC work, I wrote a technical report on how to design a C
calling sequence, but that was before the VAX. Early calling sequences
had both a stack pointer and a frame pointer, but for most machines it
was possible to get by with just one, so calling sequences got better as
time went on. Also, RISC machines with many more registers than the
PDP-11 also led to more efficient calls by putting some arguments in
registers. Later standardizations like varargs were painful on some
architectures (especially those which had different registers for pointers
and integers).
I had a look for your technical report online but my searches failed me.
Do you have a link to a copy?
Doesn't alloca() get interesting if you have a stack pointer but no frame
pointer? :-)
http://minnie.tuhs.org/cgi-bin/utree.pl?file=4BSD/usr/src/libc/sys/alloca.s
Nowadays it's usually implemented as a builtin, and given that the
compiler ought to be able to cope in most cases, but if you alloca() a
variable amount things soon get too difficult...
Tony.
--
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