Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!ncar!ico!ism780c!haddock!karl
From: karl@haddock.ima.isc.com (Karl Heuer)
Newsgroups: comp.lang.c
Subject: Re: Alloca: Its use is hazardous to the health of your program?
Keywords: alloca, malloc
Message-ID: <16822@haddock.ima.isc.com>
Date: 8 Jun 90 02:18:49 GMT
References: <1990May31.004024.29385@agate.berkeley.edu>
Reply-To: karl@haddock.ima.isc.com (Karl Heuer)
Distribution: usa
Organization: Interactive Systems, Cambridge, MA 02138-5302
Lines: 11

In article <1990May31.004024.29385@agate.berkeley.edu> andychoi@ocf.berkeley.edu (Andrew Choi) writes:
>One last question:  Why is alloca so machine-dependent?  It seems that
>it shouldn't be ...

If it's implemented as a front-end to malloc(), then it's hard to make sure
the free() gets done when the function ends.

If it's implemented by expanding the stack frame, then on machines that have
no frame pointer it can't be done without assistance from a compiler builtin.

Karl W. Z. Heuer (karl@ima.ima.isc.com or harvard!ima!karl), The Walking Lint