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From: james@raid.dell.com (James Van Artsdalen)
Newsgroups: gnu.gcc.bug
Subject: Re: GCC 1.36 (386 System V) __builtin_alloca does not align the stack.
Keywords: alloca builtins gcc-1.36 386 System V
Message-ID: <1739@uudell.dell.com>
Date: 7 Feb 90 01:30:09 GMT
References: <1965@osc.COM>
Sender: news@uudell.dell.com
Reply-To: james@raid.dell.com (James Van Artsdalen)
Distribution: na
Organization: Institute for Applied Cosmology
Lines: 19

In <1965@osc.COM>, rp@osc.COM (Rich Patterson) wrote:

> 	Here is a bug that I've found in gcc.

> Synopsis: GCC's (1.36 386 System V) builtin alloca function does not align
> 	  the stack.

> Description: When compiling GDB 3.4 with GCC 1.36 the program will
> 	core dump when starting up in tgetent.

Yes, this is a bug and not a performance issue.  This is also the
cause of a bug I have been trying to figure out in emacs for quite
some time.  The 386 (and presumably the 486) can misbehave when the
stack is not aligned.  I saw this last year in some ROM based code,
but did not get a chance to prove it with a logic analyzer.  Aligning
the stack has appeared to fix several mysterious problems.
--
James R. Van Artsdalen          james@raid.dell.com       "Live Free or Die"
Dell Computer Corporation  9505 Arboretum Blvd Austin TX 78759  512-338-8789