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From: spot@WOOZLE.GRAPHICS.CS.CMU.EDU (Scott Draves)
Newsgroups: comp.arch
Subject: Re: Optimal Computer Architectures
Message-ID: <1990Nov11.102907.7706@cs.cmu.edu>
Date: 11 Nov 90 10:29:07 GMT
References: <212412@<1990Nov8> <3300209@m.cs.uiuc.edu> <334@mentat.COM>
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Reply-To: spot@WOOZLE.GRAPHICS.CS.CMU.EDU (Scott Draves)
Organization: Carnegie Mellon University
Lines: 34

In article <334@mentat.COM>, blc@mentat.COM (Bruce Carneal) writes:
|> Hopefully the newer compilers
|> for the SPARC do/will handle tail calls without stack
|> growth.

It is my understanding that the SunOS 4.x compiler does
detect and eliminate tail recursion.  This is verified by
compiling (-O4 -S)

ENUM(i) { if (i==0) return 1; else return ENUM(i-1); }

and seeing

_ENUM:
L77001:
        tst     %o0
        bne     L77003
        nop
        retl
        add     %g0,1,%o0
L77003:
        b       L77001
        dec     %o0


It seems odd that it would generate
a branch to another branch.  can anyone
who knows comment?



			Consume
Scott Draves		Be Silent
spot@cs.cmu.edu		Die