Refactor loops in S_hsplit(), Perl_hv_ksplit() and Perl_ptr_table_split().

Change from for() to do ... while() loops. Move variable initialisation to
variable declaration. Avoid needing to use the comma operator to allow
multiple statements in for(). Avoid using a continue statement where it
isn't actually needed to change flow control. Avoid relying on the optimiser
to know that the for loop conditional doesn't need testing on the first pass.

A current gcc's optimiser produces identical code despite these changes.
However, for the reasons given I consider the code to be much clearer.

1 files changed, 7 insertions, 5 deletions

diff --git a/sv.c b/sv.c
index cc8fe49e3b..9a4a082309 100644
--- a/sv.c
+++ b/sv.c
@@ -10875,20 +10875,22 @@ Perl_ptr_table_split(pTHX_ PTR_TBL_t *const tbl)
     tbl->tbl_max = --newsize;
     tbl->tbl_ary = ary;
     for (i=0; i < oldsize; i++, ary++) {
-	PTR_TBL_ENT_t **curentp, **entp, *ent;
-	if (!*ary)
+	PTR_TBL_ENT_t **entp = ary;
+	PTR_TBL_ENT_t *ent = *ary;
+	PTR_TBL_ENT_t **curentp;
+	if (!ent)
 	    continue;
 	curentp = ary + oldsize;
-	for (entp = ary, ent = *ary; ent; ent = *entp) {
+	do {
 	    if ((newsize & PTR_TABLE_HASH(ent->oldval)) != i) {
 		*entp = ent->next;
 		ent->next = *curentp;
 		*curentp = ent;
-		continue;
 	    }
 	    else
 		entp = &ent->next;
-	}
+	    ent = *entp;
+	} while (ent);
     }
 }