From: Nicholas Clark <nick@ccl4.org>
Date: Fri, 11 Jan 2008 17:00:59 +0000 (+0000)
Subject: Pack the recycled pad offsets into an SV at PL_regex_pad[0]. This will
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=402d2eb1990caf116b392579a55f0a4f317d2738;p=p5sagit%2Fp5-mst-13.2.git

Pack the recycled pad offsets into an SV at PL_regex_pad[0]. This will
use less memory than an AV.

p4raw-id: //depot/perl@32959
---

diff --git a/intrpvar.h b/intrpvar.h
index d457028..06014ef 100644
--- a/intrpvar.h
+++ b/intrpvar.h
@@ -564,7 +564,8 @@ PERLVAR(Iregex_pad,     SV**)		/* Shortcut into the array of
 					   regex_padav */
 PERLVAR(Iregex_padav,   AV*)		/* All regex objects, indexed via the
 					   values in op_pmoffset of pmop.
-					   Entry 0 is an array of IVs listing
+					   Entry 0 is an SV whose PV is a
+					   "packed" list of IVs listing
 					   the now-free slots in the array */
 #endif
 
diff --git a/op.c b/op.c
index 3903f53..e5fed9d 100644
--- a/op.c
+++ b/op.c
@@ -623,9 +623,11 @@ clear_pmop:
          */
 #ifdef USE_ITHREADS
 	if(PL_regex_pad) {        /* We could be in destruction */
+	    const IV offset = (cPMOPo)->op_pmoffset;
 	    ReREFCNT_dec(PM_GETRE(cPMOPo));
-            av_push((AV*) PL_regex_pad[0], newSViv((cPMOPo)->op_pmoffset));
-	    PL_regex_pad[(cPMOPo)->op_pmoffset] = &PL_sv_undef;
+	    PL_regex_pad[offset] = &PL_sv_undef;
+            sv_catpvn_nomg(PL_regex_pad[0], (const char *)&offset,
+			   sizeof(offset));
         }
 #else
 	ReREFCNT_dec(PM_GETRE(cPMOPo));
@@ -3364,13 +3366,20 @@ Perl_newPMOP(pTHX_ I32 type, I32 flags)
 
 
 #ifdef USE_ITHREADS
-    if (av_len((AV*) PL_regex_pad[0]) > -1) {
-	SV * const repointer = av_pop((AV*)PL_regex_pad[0]);
-	const IV offset = SvIV(repointer);
+    assert(SvPOK(PL_regex_pad[0]));
+    if (SvCUR(PL_regex_pad[0])) {
+	/* Pop off the "packed" IV from the end.  */
+	SV *const repointer_list = PL_regex_pad[0];
+	const char *p = SvEND(repointer_list) - sizeof(IV);
+	const IV offset = *((IV*)p);
+
+	assert(SvCUR(repointer_list) % sizeof(IV) == 0);
+
+	SvEND_set(repointer_list, p);
+
 	pmop->op_pmoffset = offset;
 	/* This slot should be free, so assert this:  */
 	assert(PL_regex_pad[offset] == &PL_sv_undef);
-	SvREFCNT_dec(repointer);
     } else {
 	SV * const repointer = &PL_sv_undef;
 	av_push(PL_regex_padav, repointer);
diff --git a/perl.c b/perl.c
index 4397087..e8821a5 100644
--- a/perl.c
+++ b/perl.c
@@ -353,8 +353,9 @@ perl_construct(pTHXx)
     sv_setpvn(PERL_DEBUG_PAD(1), "", 0);	/* ext/re needs these */
     sv_setpvn(PERL_DEBUG_PAD(2), "", 0);	/* even without DEBUGGING. */
 #ifdef USE_ITHREADS
-    /* First entry is an array of empty elements */
-    Perl_av_create_and_push(aTHX_ &PL_regex_padav,(SV*)newAV());
+    /* First entry is a list of empty elements. It needs to be initialised
+       else all hell breaks loose in S_find_uninit_var().  */
+    Perl_av_create_and_push(aTHX_ &PL_regex_padav, newSVpvs(""));
     PL_regex_pad = AvARRAY(PL_regex_padav);
 #endif
 #ifdef USE_REENTRANT_API