ldgp instruction on Alpha

Hi compiler hackers,


I'm using gcc on digital unix.


Prologue sequences for procedures begin with an instruction like


foo:
ldgp $29,0($27)
...


There is a similar instruction where a procedure call returns:


jsr $26,printf ! call printf
ldgp $29,0($26)




Could anybody tell me what are these ldgp instructions for? I read
some materials which say $27 is a "procedure value" pointer and $29
has something to do with global variables. But I have never seen any
instruction which really uses those registers. I appreciate any
information or pointers to information about this.


I'm also looking for any books or any materials for such programming
issues on alpha. I can access to a lot of architecture manual, but
none has enough description about software considerations like the
above.


Thanks.
--
Kenjiro Taura
Yonezawa Laboratory
Department of Information Science
Faculty of Science
University of Tokyo
7-3-1 Hongo, Bunkyo-ku Tokyo 113 Japan
tau@is.s.u-tokyo.ac.jp (http://web.yl.is.s.u-tokyo.ac.jp/)
tel: +81-3-3812-2111 ext. 4108 or +81-3-5800-6913
fax: +81-3-5689-4365
--

Return to the comp.compilers page.
Search the comp.compilers archives again.