If NV_ZERO_IS_ALLBITS_ZERO there's no need to explicitly set the NVX

to 0.0, as the memset has already done it.

p4raw-id: //depot/perl@24899

diff --git a/sv.c b/sv.c
index 44b5b34..169065a 100644 (file)
--- a/sv.c
+++ b/sv.c
@@ -1276,7 +1276,11 @@ Perl_sv_upgrade(pTHX_ register SV *sv, U32 mt)
     size_t     old_body_offset;
     size_t     old_body_length;        /* Well, the length to copy.  */
     void*      old_body;
+#ifndef NV_ZERO_IS_ALLBITS_ZERO
+    /* If NV 0.0 is store as all bits 0 then Zero() already creates a correct
+       0.0 for us.  */
     bool       zero_nv = TRUE;
+#endif
     void*      new_body;
     size_t     new_body_length;
     size_t     new_body_offset;
@@ -1353,8 +1357,9 @@ Perl_sv_upgrade(pTHX_ register SV *sv, U32 mt)
     case SVt_NV:
        old_body_arena = (void **) &PL_xnv_root;
        old_body_length = sizeof(NV);
+#ifndef NV_ZERO_IS_ALLBITS_ZERO
        zero_nv = FALSE;
-
+#endif
        if (mt < SVt_PVNV)
            mt = SVt_PVNV;
        break;
@@ -1384,7 +1389,9 @@ Perl_sv_upgrade(pTHX_ register SV *sv, U32 mt)
        old_body_arena = (void **) &PL_xpvnv_root;
        old_body_length = STRUCT_OFFSET(XPVNV, xiv_u)
            + sizeof (((XPVNV*)SvANY(sv))->xiv_u);
+#ifndef NV_ZERO_IS_ALLBITS_ZERO
        zero_nv = FALSE;
+#endif
        break;
     case SVt_PVMG:
        /* Because the XPVMG of PL_mess_sv isn't allocated from the arena,
@@ -1398,7 +1405,9 @@ Perl_sv_upgrade(pTHX_ register SV *sv, U32 mt)
        old_body_arena = (void **) &PL_xpvmg_root;
        old_body_length = STRUCT_OFFSET(XPVMG, xmg_stash)
            + sizeof (((XPVMG*)SvANY(sv))->xmg_stash);
+#ifndef NV_ZERO_IS_ALLBITS_ZERO
        zero_nv = FALSE;
+#endif
        break;
     default:
        Perl_croak(aTHX_ "Can't upgrade that kind of scalar");
@@ -1521,43 +1530,43 @@ Perl_sv_upgrade(pTHX_ register SV *sv, U32 mt)
        new_body_arenaroot = (void **) &PL_xpv_arenaroot;
     new_body_no_NV:
        /* PV and PVIV don't have an NV slot.  */
+#ifndef NV_ZERO_IS_ALLBITS_ZERO
        zero_nv = FALSE;
+#endif
 
-       {
-       new_body:
-           assert(new_body_length);
+    new_body:
+       assert(new_body_length);
 #ifndef PURIFY
-           /* This points to the start of the allocated area.  */
-           new_body = S_new_body(aTHX_ new_body_arenaroot, new_body_arena,
-                                 new_body_length);
+       /* This points to the start of the allocated area.  */
+       new_body = S_new_body(aTHX_ new_body_arenaroot, new_body_arena,
+                             new_body_length);
 #else
-           /* We always allocated the full length item with PURIFY */
-           new_body_length += new_body_offset;
-           new_body_offset = 0;
-           new_body = my_safemalloc(new_body_length);
+       /* We always allocated the full length item with PURIFY */
+       new_body_length += new_body_offset;
+       new_body_offset = 0;
+       new_body = my_safemalloc(new_body_length);
 
 #endif
-       zero:
-           Zero(new_body, new_body_length, char);
-           new_body = ((char *)new_body) - new_body_offset;
-           SvANY(sv) = new_body;
-
-           if (old_body_length) {
-               Copy((char *)old_body + old_body_offset,
-                    (char *)new_body + old_body_offset,
-                    old_body_length, char);
-           }
-
-           /* FIXME - add a Configure test to determine if NV 0.0 is actually
-              all bits zero. If it is, we can skip this initialisation.  */
-           if (zero_nv)
-               SvNV_set(sv, 0);
+    zero:
+       Zero(new_body, new_body_length, char);
+       new_body = ((char *)new_body) - new_body_offset;
+       SvANY(sv) = new_body;
 
-           if (mt == SVt_PVIO)
-               IoPAGE_LEN(sv)  = 60;
-           if (old_type < SVt_RV)
-               SvPV_set(sv, 0);
+       if (old_body_length) {
+           Copy((char *)old_body + old_body_offset,
+                (char *)new_body + old_body_offset,
+                old_body_length, char);
        }
+
+#ifndef NV_ZERO_IS_ALLBITS_ZERO
+       if (zero_nv)
+           SvNV_set(sv, 0);
+#endif
+
+       if (mt == SVt_PVIO)
+           IoPAGE_LEN(sv)      = 60;
+       if (old_type < SVt_RV)
+           SvPV_set(sv, 0);
        break;
     default:
        Perl_croak(aTHX_ "panic: sv_upgrade to unknown type %lu", mt);