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From: "D'Arcy J.M. Cain" <darcy@druid.net>

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Subject: [HACKERS] backend/optimizer/geqo/geqo_erx.c

I sent these changes in with a bunch of others.  Some were folded in but
others, like these, were not.  I am not sure why so I am resending this
to the developers list by itself for discussion.

The readon why I suggest these changes is that the compiler can't tell
that minimum_count is initialized before it is used.  The tests that I
add in here will cause an immediate error if it doesn't.  As the comments
below suggest, if it is 100% guaranteed that the variable will always
be initialized then how this is so should be commented here.  I don't
know how much strain the actual test puts on the performance but if it
isn't too much then maybe leave it in for absolute safety anyway.

There are also a few returns just to stop warnings.
This commit is contained in:
Marc G. Fournier 1997-06-06 00:37:23 +00:00
parent a668b7ac2d
commit f50b103ce1
1 changed files with 21 additions and 10 deletions
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15
src/backend/optimizer/geqo/geqo_erx.c
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@ -3,7 +3,7 @@
* geqo_erx.c-- * geqo_erx.c--
* edge recombination crossover [ER] * edge recombination crossover [ER]
* *
* $Id: geqo_erx.c,v 1.1 1997/02/19 12:56:55 scrappy Exp $ * $Id: geqo_erx.c,v 1.2 1997/06/06 00:37:23 scrappy Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -278,7 +278,7 @@ gimme_gene (Edge edge, Edge *edge_table)
int i; int i;
Gene friend; Gene friend;
int minimum_edges; int minimum_edges;
int minimum_count; int minimum_count = -1;
int rand_decision; int rand_decision;
/* no point has edges to more than 4 other points /* no point has edges to more than 4 other points
@ -304,10 +304,19 @@ gimme_gene (Edge edge, Edge *edge_table)
if there is more than one cadidate with the minimum number if there is more than one cadidate with the minimum number
of unused edges keep count of this number (minimum_count); */ of unused edges keep count of this number (minimum_count); */
/* The test for minimum_count can probably be removed at some
point but comments should probably indicate exactly why it
is guaranteed that the test will always succeed the first
time around. If it can fail then the code is in error */
if (edge_table[(int) friend].unused_edges < minimum_edges) { if (edge_table[(int) friend].unused_edges < minimum_edges) {
minimum_edges = edge_table[(int) friend].unused_edges; minimum_edges = edge_table[(int) friend].unused_edges;
minimum_count = 1; minimum_count = 1;
} }
else
if (minimum_count == -1)
elog(WARN, "gimme_gene: Internal error - minimum_count not set");
else else
if (edge_table[(int) friend].unused_edges == minimum_edges) if (edge_table[(int) friend].unused_edges == minimum_edges)
minimum_count++; minimum_count++;
@ -332,6 +341,7 @@ gimme_gene (Edge edge, Edge *edge_table)
/* ... should never be reached */ /* ... should never be reached */
elog(WARN,"gimme_gene: neither shared nor minimum number nor random edge found"); elog(WARN,"gimme_gene: neither shared nor minimum number nor random edge found");
return 0; /* to keep the compiler quiet */
} }
/* edge_failure-- /* edge_failure--
@ -420,5 +430,6 @@ edge_failure (Gene *gene, int index, Edge *edge_table, int num_gene)
/* ... should never be reached */ /* ... should never be reached */
elog(WARN,"edge_failure: no edge detected"); elog(WARN,"edge_failure: no edge detected");
return 0; /* to keep the compiler quiet */
} }