From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: pgsql-hackers@lists.postgresql.org
Subject: Re: Some regular-expression performance hacking
In-reply-to: <3874948.1614101949@sss.pgh.pa.us>
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 <3874948.1614101949@sss.pgh.pa.us>
Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Tue, 23 Feb 2021 12:39:09 -0500"
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Date: Tue, 23 Feb 2021 12:52:28 -0500
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I wrote:
> Hmph.  There's an "assert(depth >= 0)" immediately in front of that,
> so I'm not looking too kindly on the compiler thinking it's smarter
> than I am.  Do you have a suggestion on how to shut it up?

On reflection, maybe the thing to do is convert the assert into
an always-on check, "if (depth < 0) return false".  The assertion
is essentially saying that there's no arc leading directly from
the pre state to the post state.  Which there had better not be,
or a lot of other stuff is going to go wrong; but I suppose there's
no way to explain that to gcc.  It is annoying to have to expend
an always-on check for a can't-happen case, though.

			regards, tom lane