From: Heikki Linnakangas <heikki@enterprisedb.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Alvaro Herrera <alvherre@commandprompt.com>
Cc: Stefan Kaltenbrunner <stefan@kaltenbrunner.cc>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: compiler warnings on the buildfarm
Date: Thu, 12 Jul 2007 23:50:45 +0100
Message-ID: <4696B045.8080405@enterprisedb.com> (raw)
In-Reply-To: <12639.1184279380@sss.pgh.pa.us>
References: <46962BBD.5000108@kaltenbrunner.cc>
<17428.1184249229@sss.pgh.pa.us>
<469653BA.2040004@kaltenbrunner.cc>
<20070712211918.GD22973@alvh.no-ip.org>
<46969C98.60207@enterprisedb.com>
<20070712213806.GE22973@alvh.no-ip.org>
<4696A5F1.3010103@enterprisedb.com>
<12639.1184279380@sss.pgh.pa.us>
Tom Lane wrote:
> Heikki Linnakangas <heikki@enterprisedb.com> writes:
>> Hmm. It looks like I get that warning on my laptop as well. I tracked it
>> down to these two places:
>
>> Line 209:
>>> while (ptr - GETARR(trg) < ARRNELEM(trg))
>>> {
>>> text *item = (text *) palloc(VARHDRSZ + 3);
>>>
>>> SET_VARSIZE(item, VARHDRSZ + 3);
>>> CPTRGM(VARDATA(item), ptr);
>>>>> d[ptr - GETARR(trg)] = PointerGetDatum(item);
>>> ptr++;
>>> }
>
> I'll betcha the compiler is trying to optimize the repeated calculations
> of "ptr - GETARR(trg)" into a separate variable that it increments along
> with ptr. Maybe it is getting it wrong, or maybe the assembler is just
> confused. Does the warning go away if you dial down the -O level?
FWIW, this patch makes the warnings go away, and makes the code a little
bit more readable as well. It would be nice to understand why exactly
it's complaining, though.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.comAttachments:trgm-silence-warning.patch (text/x-diff, 1.6K) download
Index: trgm_op.c
===================================================================
RCS file: /home/hlinnaka/pgcvsrepository/pgsql/contrib/pg_trgm/trgm_op.c,v
retrieving revision 1.8
diff -c -r1.8 trgm_op.c
*** trgm_op.c 28 Feb 2007 22:44:38 -0000 1.8
--- trgm_op.c 12 Jul 2007 22:28:43 -0000
***************
*** 194,212 ****
Datum *d;
ArrayType *a;
trgm *ptr;
trg = generate_trgm(VARDATA(in), VARSIZE(in) - VARHDRSZ);
d = (Datum *) palloc(sizeof(Datum) * (1 + ARRNELEM(trg)));
! ptr = GETARR(trg);
! while (ptr - GETARR(trg) < ARRNELEM(trg))
{
text *item = (text *) palloc(VARHDRSZ + 3);
SET_VARSIZE(item, VARHDRSZ + 3);
CPTRGM(VARDATA(item), ptr);
! d[ptr - GETARR(trg)] = PointerGetDatum(item);
! ptr++;
}
a = construct_array(
--- 194,211 ----
Datum *d;
ArrayType *a;
trgm *ptr;
+ int i;
trg = generate_trgm(VARDATA(in), VARSIZE(in) - VARHDRSZ);
d = (Datum *) palloc(sizeof(Datum) * (1 + ARRNELEM(trg)));
! for (i = 0, ptr = GETARR(trg); i < ARRNELEM(trg); i++, ptr++)
{
text *item = (text *) palloc(VARHDRSZ + 3);
SET_VARSIZE(item, VARHDRSZ + 3);
CPTRGM(VARDATA(item), ptr);
! d[i] = PointerGetDatum(item);
}
a = construct_array(
***************
*** 218,229 ****
'i'
);
! ptr = GETARR(trg);
! while (ptr - GETARR(trg) < ARRNELEM(trg))
! {
! pfree(DatumGetPointer(d[ptr - GETARR(trg)]));
! ptr++;
! }
pfree(d);
pfree(trg);
--- 217,224 ----
'i'
);
! for (i = 0; i < ARRNELEM(trg); i++)
! pfree(DatumGetPointer(d[i]));
pfree(d);
pfree(trg);
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To: pgsql-hackers@postgresql.org
Cc: heikki@enterprisedb.com, tgl@sss.pgh.pa.us, alvherre@commandprompt.com, stefan@kaltenbrunner.cc
Subject: Re: compiler warnings on the buildfarm
In-Reply-To: <4696B045.8080405@enterprisedb.com>
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