From 29912d932cee5589d4165d5eff62d0cc4f2c5195 Mon Sep 17 00:00:00 2001
From: Nicholas Clark <nick@ccl4.org>
Date: Mon, 11 Oct 2010 13:12:04 +0100
Subject: 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.
---
 sv.c | 36 +++++++++++++++---------------------
 1 file 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';
-- 
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