Avoid calling Gcovert() when stringifying 0.0 and -0.0

Previously we always called Gconvert(), then tested its string output, then
fixed that up if necessary. This way has fewer tests. We can also reduce the
memory allocation for the string output for the case of zero.

1 files changed, 15 insertions, 21 deletions

diff --git a/sv.c b/sv.c
index 106fc1842f..8365664882 100644
--- a/sv.c
+++ b/sv.c
@@ -2733,6 +2733,10 @@ Perl_sv_2pv_flags(pTHX_ register SV *const sv, STRLEN *const lp, const I32 flags
 		len = SvIsUV(sv)
 		    ? my_snprintf(tbuf, sizeof(tbuf), "%"UVuf, (UV)SvUVX(sv))
 		    : my_snprintf(tbuf, sizeof(tbuf), "%"IVdf, (IV)SvIVX(sv));
+	    } else if(SvNVX(sv) == 0.0) {
+		    tbuf[0] = '0';
+		    tbuf[1] = 0;
+		    len = 1;
 	    } else {
 		Gconvert(SvNVX(sv), NV_DIG, 0, tbuf);
 		len = strlen(tbuf);
@@ -2741,11 +2745,6 @@ Perl_sv_2pv_flags(pTHX_ register SV *const sv, STRLEN *const lp, const I32 flags
 	    {
 		dVAR;
 
-		if (len == 2 && tbuf[0] == '-' && tbuf[1] == '0') {
-		    tbuf[0] = '0';
-		    tbuf[1] = 0;
-		    len = 1;
-		}
 		SvUPGRADE(sv, SVt_PV);
 		if (lp)
 		    *lp = len;
@@ -2917,26 +2916,21 @@ Perl_sv_2pv_flags(pTHX_ register SV *const sv, STRLEN *const lp, const I32 flags
 	*s = '\0';
     }
     else if (SvNOKp(sv)) {
-	dSAVE_ERRNO;
 	if (SvTYPE(sv) < SVt_PVNV)
 	    sv_upgrade(sv, SVt_PVNV);
-	/* The +20 is pure guesswork.  Configure test needed. --jhi */
-	s = SvGROW_mutable(sv, NV_DIG + 20);
-	/* some Xenix systems wipe out errno here */
-#ifdef apollo
-	if (SvNVX(sv) == 0.0)
-	    my_strlcpy(s, "0", SvLEN(sv));
-	else
-#endif /*apollo*/
-	{
+	if (SvNVX(sv) == 0.0) {
+	    s = SvGROW_mutable(sv, 2);
+	    *s++ = '0';
+	    *s = '\0';
+	} else {
+	    dSAVE_ERRNO;
+	    /* The +20 is pure guesswork.  Configure test needed. --jhi */
+	    s = SvGROW_mutable(sv, NV_DIG + 20);
+	    /* some Xenix systems wipe out errno here */
 	    Gconvert(SvNVX(sv), NV_DIG, 0, s);
+	    RESTORE_ERRNO;
+	    while (*s) s++;
 	}
-	RESTORE_ERRNO;
-        if (*s == '-' && s[1] == '0' && !s[2]) {
-	    s[0] = '0';
-	    s[1] = 0;
-	}
-	while (*s) s++;
 #ifdef hcx
 	if (s[-1] == '.')
 	    *--s = '\0';