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Postings from October 2005
> [nicholas - Wed Jun 01 11:21:50 2005]:
>
> This is a bug report for perl from nick@ccl4.org,
> generated with the help of perlbug 1.35 running under perl v5.9.3.
>
>
> -----------------------------------------------------------------
> [Please enter your report here]
>
> We should audit the perl source for all uses of Newz(), to see which
> are
> wasteful. In many cases we don't need to explicity memzero any of the
> freshly allocated memory, as the subsequent code writes to every
> location
> in it. For example:
>
> if (!mg->mg_ptr) {
> Newz(0, cache, PERL_MAGIC_UTF8_CACHESIZE * 2, STRLEN);
> mg->mg_ptr = (char *) cache;
> }
> assert(cache);
>
> cache[0] = len;
> cache[1] = *offsetp;
> /* Drop the stale "length" cache */
> cache[2] = 0;
> cache[3] = 0;
>
> In others, we can make do with zeroing a lot less:
>
> if (AvARRAY((AV*)sstr)) {
> SV **dst_ary, **src_ary;
> SSize_t items = AvFILLp((AV*)sstr) + 1;
>
> src_ary = AvARRAY((AV*)sstr);
> Newz(0, dst_ary, AvMAX((AV*)sstr)+1, SV*);
> ptr_table_store(PL_ptr_table, src_ary, dst_ary);
> SvPV_set(dstr, (char*)dst_ary);
> AvALLOC((AV*)dstr) = dst_ary;
> if (AvREAL((AV*)sstr)) {
> while (items-- > 0)
> *dst_ary++ = sv_dup_inc(*src_ary++, param);
> }
> else {
> while (items-- > 0)
> *dst_ary++ = sv_dup(*src_ary++, param);
> }
> items = AvMAX((AV*)sstr) - AvFILLp((AV*)sstr);
> while (items-- > 0) {
> *dst_ary++ = &PL_sv_undef;
> }
>
>
> We may get some speedup here, particularly for ithread duplication.
It looks like Newz() is gone from the core, mainly replaced with
Newxz(), it appears. Shoule Newxz() be investigated instead?
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