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Re: inline newNode()

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Peter Eisentraut <peter_e(at)gmx(dot)net>,Neil Conway <neilc(at)samurai(dot)com>,PostgreSQL Patches <pgsql-patches(at)postgresql(dot)org>
Subject: Re: inline newNode()
Date: 2002-10-09 04:35:06
Message-ID: 200210090435.g994Z6B07015@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > Right, palloc shouldn't.  I was thinking of having another version of
> > palloc that _does_ clear out memory, and calling that from a newNode()
> > macro.  We already know palloc is going to call MemoryContextAlloc, so
> > we could have a pallocC() that calls a new MemoryContextAllocC() that
> > would call the underlying memory allocation function, then do the loop
> > like MemSet to clear it.
> 
> But if the MemSet is inside the called function then it cannot reduce
> the if-tests to a compile-time decision to invoke the word-zeroing loop.
> We want the MemSet to be expanded at the newNode call site, where the
> size of the allocated memory is a compile-time constant.

I can easily do the tests in the MemSet macro, but I can't do a loop in
a macro that has to return a value;  I need while().  Though a loop in a
new fuction will not be as fast as a MemSet macro, I think it will be
better than what we have now with newNode only because newNode will be a
macro and not a function anymore, i.e. the MemSet will happen in the
function called by pallocC and not in newNode anymore, and there will be
zero code bloat.  I wish I saw another way.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

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