add old_tmpsfloor field to CXt_SUB context frame

Rather than saving and restoring PL_tmps_floor on subroutine entry/exit
by using SAVETMPS and the save stack, store the old value directly
in the context struct and make PUSHSUB/POPSUB handle the saving and
restoring.

cop.h

@@ -556,6 +556,7 @@ struct block_sub {
     AV *	savearray;
     I32		olddepth;
     PAD		*prevcomppad; /* the caller's PL_comppad */
+    SSize_t     old_tmpsfloor; /* also used in CXt_NULL sort block */
 };
 
 
@@ -587,7 +588,9 @@ struct block_format {
 	cx->blk_sub.prevcomppad = PL_comppad;				\
 	cx->cx_type |= (hasargs) ? CXp_HASARGS : 0;			\
 	cx->blk_sub.retop = NULL;					\
-        SvREFCNT_inc_simple_void_NN(cv);
+        SvREFCNT_inc_simple_void_NN(cv);                                \
+        cx->blk_sub.old_tmpsfloor = PL_tmps_floor;                      \
+        PL_tmps_floor = PL_tmps_ix;
 
 #define PUSHSUB_GET_LVALUE_MASK(func) \
 	/* If the context is indeterminate, then only the lvalue */	\
@@ -669,6 +672,7 @@ struct block_format {
         }                                                               \
 	sv = MUTABLE_SV(cx->blk_sub.cv);				\
 	LEAVE_SCOPE(PL_scopestack[cx->blk_oldscopesp-1]);		\
+        PL_tmps_floor = cx->blk_sub.old_tmpsfloor;                      \
         PL_comppad = cx->blk_sub.prevcomppad;                           \
         PL_curpad = LIKELY(PL_comppad) ? AvARRAY(PL_comppad) : NULL;    \
         CvDEPTH((const CV*)sv) = olddepth;                              \
@@ -1228,7 +1232,6 @@ See L<perlcall/LIGHTWEIGHT CALLBACKS>.
 	PUSHSTACKi(PERLSI_MULTICALL);					\
 	PUSHBLOCK(cx, (CXt_SUB|CXp_MULTICALL|flags), PL_stack_sp);	\
 	PUSHSUB(cx);							\
-        SAVETMPS;                                                       \
         if (!(flags & CXp_SUB_RE_FAKE))                                 \
             CvDEPTH(cv)++;						\
 	if (CvDEPTH(cv) >= 2) {						\
@@ -1270,14 +1273,22 @@ See L<perlcall/LIGHTWEIGHT CALLBACKS>.
 	CV * const _nOnclAshIngNamE_ = the_cv;				\
 	CV * const cv = _nOnclAshIngNamE_;				\
 	PADLIST * const padlist = CvPADLIST(cv);			\
-        PAD * const prevcomppad = cx->blk_sub.prevcomppad;              \
 	cx = &cxstack[cxstack_ix];					\
 	assert(cx->cx_type & CXp_MULTICALL);				\
 	CvDEPTH(multicall_cv) = cx->blk_sub.olddepth;                   \
         LEAVESUB(multicall_cv);					        \
 	cx->cx_type = (CXt_SUB|CXp_MULTICALL|flags);                    \
-	PUSHSUB(cx);							\
-        cx->blk_sub.prevcomppad = prevcomppad ; /* undo PUSHSUB */      \
+        {                                                               \
+            /* save a few things that we don't want PUSHSUB to zap */   \
+            PAD * const prevcomppad = cx->blk_sub.prevcomppad;          \
+            SSize_t old_floor = cx->blk_sub.old_tmpsfloor;              \
+            SSize_t floor = PL_tmps_floor;                              \
+	    PUSHSUB(cx);						\
+            /* undo the stuff that PUSHSUB zapped */                    \
+            cx->blk_sub.prevcomppad = prevcomppad ;                     \
+            cx->blk_sub.old_tmpsfloor = old_floor;                      \
+            PL_tmps_floor = floor;                                      \
+        }                                                               \
         if (!(flags & CXp_SUB_RE_FAKE))                                 \
             CvDEPTH(cv)++;						\
 	if (CvDEPTH(cv) >= 2) {						\

pp_ctl.c

@@ -1975,7 +1975,6 @@ PP(pp_dbstate)
 	else {
 	    PUSHBLOCK(cx, CXt_SUB, SP);
 	    PUSHSUB_DB(cx);
-            SAVETMPS;
 	    cx->blk_sub.retop = PL_op->op_next;
 	    CvDEPTH(cv)++;
 	    if (CvDEPTH(cv) >= 2) {
@@ -2832,7 +2831,6 @@ PP(pp_goto)
 	    else {
 		PADLIST * const padlist = CvPADLIST(cv);
 
-                SAVETMPS;
                 SAVEFREESV(cv); /* later, undo the 'avoid premature free' hack */
 
                 /* partial unrolled PUSHSUB(): */

pp_hot.c

@@ -3516,7 +3516,6 @@ PP(pp_entersub)
 
 	PUSHBLOCK(cx, CXt_SUB, MARK);
 	PUSHSUB(cx);
-	SAVETMPS;
 
 	cx->blk_sub.retop = PL_op->op_next;
 	if (UNLIKELY((depth = ++CvDEPTH(cv)) >= 2)) {

pp_sort.c

@@ -1672,7 +1672,6 @@ PP(pp_sort)
 	    if (!(flags & OPf_SPECIAL)) {
 		cx->cx_type = CXt_SUB;
 		PUSHSUB(cx);
-                SAVETMPS;
 		if (!is_xsub) {
 		    PADLIST * const padlist = CvPADLIST(cv);
 
@@ -1692,8 +1691,12 @@ PP(pp_sort)
 
 		}
 	    }
-            else
-                SAVETMPS;
+            else {
+                /* mimic PUSHSUB. Note that we're cheating and using a
+                 * CXt_NULL block as a CXt_SUB block */
+                cx->blk_sub.old_tmpsfloor = PL_tmps_floor;
+                PL_tmps_floor = PL_tmps_ix;
+            }
 
 	    cx->cx_type |= CXp_MULTICALL;
 
@@ -1710,6 +1713,10 @@ PP(pp_sort)
 		POPSUB(cx, sv);
 		LEAVESUB(sv);
 	    }
+            else
+                /* mimic POPSUB */
+                PL_tmps_floor = cx->blk_sub.old_tmpsfloor;
+
 	    POPBLOCK(cx,PL_curpm);
 	    PL_stack_sp = newsp;
 	    POPSTACK;