Path: utzoo!utgpu!attcan!uunet!samsung!brutus.cs.uiuc.edu!wuarchive!husc6!endor!siegel
From: siegel@endor.harvard.edu (Rich Siegel)
Newsgroups: comp.sys.mac.programmer
Subject: Re: THINK C build speed-up
Message-ID: <3070@husc6.harvard.edu>
Date: 6 Nov 89 15:24:08 GMT
References: <5804@ucdavis.ucdavis.edu> <32366@ucbvax.BERKELEY.EDU>
Sender: news@husc6.harvard.edu
Reply-To: siegel@endor.UUCP (Rich Siegel)
Organization: Symantec Language Products Group
Lines: 39

In article <32366@ucbvax.BERKELEY.EDU> oster@dewey.soe.berkeley.edu.UUCP (David Phillip Oster) writes:

>LightSpeed Pascal code was full of no-ops, to leave hooks for the
>debugger. THINK C doesn't work that way.

	Um, no.

	Lightspeed Pascal version 1 procedures would sometimes have a
NOP at the beginning and the end of a procedure, if the code generator
discovered that there were no locals, no arguments, and no compiler
temps. In such cases, the code generator would go back and replace the
LINK A6, #n with a NOP, and replace the UNLK A6 with a NOP. So at worst
case, there would be a pair of NOPs in a procedure or function.

	Code compiled with Debug on has TRAP instructions in it, but no
NOP instructions.

	Code compiled under version 2 or later (!) has no NOP instructions
in it, period.

	In THINK C, the debug information is separate from the code; this
means that there is no special code required for debugging, and therefor
no rebuild step for building a non-debug application. On the other hand,
the optimizer sometimes gets in the way of debugging (such as making it i
impossible to crawl the stack by eliminating LINK/UNLK when appropriate).

R.

~~~~~~~~~~~~~~~
 Rich Siegel
 Staff Software Developer
 Symantec Corporation, Language Products Group
 Internet: siegel@endor.harvard.edu
 UUCP: ..harvard!endor!siegel

"There is no personal problem which cannot be solved by sufficient
application of high explosives."

~~~~~~~~~~~~~~~