Define a new SAVEt_HINT_HH type

Rather than possibly push an extra HV* to the save stack if the right
bit is set in the (saved) hints flags, better just to define a different
SAVEt type. Having done this, the stack layout is now constant per type
value.

This fixes

  https://github.com/Perl/perl5/issues/17895

3 files changed, 21 insertions, 15 deletions

diff --git a/scope.c b/scope.c
index df2e3c7194..5b4fe1131c 100644
--- a/scope.c
+++ b/scope.c
@@ -686,7 +686,14 @@ Perl_save_hints(pTHX)
     COPHH *save_cophh = cophh_copy(CopHINTHASH_get(&PL_compiling));
     if (PL_hints & HINT_LOCALIZE_HH) {
 	HV *oldhh = GvHV(PL_hintgv);
-	save_pushptri32ptr(oldhh, PL_hints, save_cophh, SAVEt_HINTS);
+        {
+            dSS_ADD;
+            SS_ADD_INT(PL_hints);
+            SS_ADD_PTR(save_cophh);
+            SS_ADD_PTR(oldhh);
+            SS_ADD_UV(SAVEt_HINTS_HH);
+            SS_ADD_END(4);
+        }
 	GvHV(PL_hintgv) = NULL; /* in case copying dies */
 	GvHV(PL_hintgv) = hv_copy_hints_hv(oldhh);
         SAVEFEATUREBITS();
@@ -863,7 +870,8 @@ static const U8 arg_counts[] = {
     3, /* SAVEt_SET_SVFLAGS        */
     3, /* SAVEt_GVSLOT             */
     3, /* SAVEt_AELEM              */
-    3  /* SAVEt_DELETE             */
+    3, /* SAVEt_DELETE             */
+    3  /* SAVEt_HINTS_HH           */
 };
 
 
@@ -1347,13 +1355,11 @@ Perl_leave_scope(pTHX_ I32 base)
 	    PL_op = (OP*)a0.any_ptr;
 	    break;
 
-	case SAVEt_HINTS:
-        {
-	    HV *was_hinthv;
+        case SAVEt_HINTS_HH:
+            a2 = ap[2];
+            /* FALLTHROUGH */
+        case SAVEt_HINTS:
             a0 = ap[0]; a1 = ap[1];
-            if (a0.any_i32 & HINT_LOCALIZE_HH) {
-                was_hinthv = MUTABLE_HV(SSPOPPTR);
-            }
 	    if ((PL_hints & HINT_LOCALIZE_HH)) {
 	      while (GvHV(PL_hintgv)) {
 		HV *hv = GvHV(PL_hintgv);
@@ -1364,9 +1370,9 @@ Perl_leave_scope(pTHX_ I32 base)
 	    cophh_free(CopHINTHASH_get(&PL_compiling));
 	    CopHINTHASH_set(&PL_compiling, (COPHH*)a1.any_ptr);
 	    *(I32*)&PL_hints = a0.any_i32;
-	    if (PL_hints & HINT_LOCALIZE_HH) {
+	    if (type == SAVEt_HINTS_HH) {
 		SvREFCNT_dec(MUTABLE_SV(GvHV(PL_hintgv)));
-                GvHV(PL_hintgv) = was_hinthv;
+                GvHV(PL_hintgv) = MUTABLE_HV(a2.any_ptr);
 	    }
 	    if (!GvHV(PL_hintgv)) {
 		/* Need to add a new one manually, else rv2hv can
@@ -1377,7 +1383,6 @@ Perl_leave_scope(pTHX_ I32 base)
 	    }
 	    assert(GvHV(PL_hintgv));
 	    break;
-        }
 
 	case SAVEt_COMPPAD:
             a0 = ap[0];
diff --git a/scope.h b/scope.h
index 483bc5d700..176ac94356 100644
--- a/scope.h
+++ b/scope.h
@@ -75,6 +75,7 @@
 #define SAVEt_GVSLOT		51
 #define SAVEt_AELEM		52
 #define SAVEt_DELETE		53
+#define SAVEt_HINTS_HH		54
 
 
 #define SAVEf_SETMAGIC		1
diff --git a/sv.c b/sv.c
index 824b8a0940..9e3226f76d 100644
--- a/sv.c
+++ b/sv.c
@@ -14996,16 +14996,16 @@ Perl_ss_dup(pTHX_ PerlInterpreter *proto_perl, CLONE_PARAMS* param)
 	    ptr = POPPTR(ss,ix);
 	    TOPPTR(nss,ix) = ptr;
 	    break;
+        case SAVEt_HINTS_HH:
+            hv = (const HV *)POPPTR(ss,ix);
+            TOPPTR(nss,ix) = hv_dup_inc(hv, param);
+            /* FALLTHROUGH */
 	case SAVEt_HINTS:
 	    ptr = POPPTR(ss,ix);
 	    ptr = cophh_copy((COPHH*)ptr);
 	    TOPPTR(nss,ix) = ptr;
 	    i = POPINT(ss,ix);
 	    TOPINT(nss,ix) = i;
-	    if (i & HINT_LOCALIZE_HH) {
-		hv = (const HV *)POPPTR(ss,ix);
-		TOPPTR(nss,ix) = hv_dup_inc(hv, param);
-	    }
 	    break;
 	case SAVEt_PADSV_AND_MORTALIZE:
 	    longval = (long)POPLONG(ss,ix);