[perl #109542] Make num ops treat $1 as "$1"

Numeric ops were not taking magical variables into account.  So $1 (a
magical variable) would be treated differently from "$1" (a non-magi-
cal variable0.

In determining whether to use an integer operation, they would call
SvIV_please_nomg, and then check whether the sv was SvIOK as a result.

SvIV_please_nomg would call SvIV_nomg if the sv were SvPOK or SvNOK.

The problem here is that gmagical variables are never SvIOK, but
only SvIOKp.

In fact, the private flags are used differently for gmagical and non-
magical variables.  For non-gmagical variables, the private flag indi-
cates that there is a cached value.  If the public flag is not set,
then the cached value is imprecise.  For gmagical variables, imprecise
values are never cached; only the private flags are used, and they are
equivalent to the public flags on non-gmagical variables.

This commit changes SvIV_please_nomg to take gmagical variables
into account, using the newly-added sv_gmagical_2iv_please (see the
docs for it in the diff).  SvIV_please_nomg now returns true or
false, not void, since a subsequent SvIOK is not reliable.  So
‘SvIV_please_nomg(sv); if(SvIOK)’ becomes ‘if(SvIV_please_nomg(sv))’.

1 files changed, 10 insertions, 32 deletions

diff --git a/pp.c b/pp.c
index 0370caa27b..fbeb3ae29a 100644
--- a/pp.c
+++ b/pp.c
@@ -1024,11 +1024,7 @@ PP(pp_pow)
     /* For integer to integer power, we do the calculation by hand wherever
        we're sure it is safe; otherwise we call pow() and try to convert to
        integer afterwards. */
-    {
-	SvIV_please_nomg(svr);
-	if (SvIOK(svr)) {
-	    SvIV_please_nomg(svl);
-	    if (SvIOK(svl)) {
+    if (SvIV_please_nomg(svr) && SvIV_please_nomg(svl)) {
 		UV power;
 		bool baseuok;
 		UV baseuv;
@@ -1126,8 +1122,6 @@ PP(pp_pow)
 			RETURN;
 		    } 
 		}
-	    }
-	}
     }
   float_it:
 #endif    
@@ -1191,14 +1185,12 @@ PP(pp_multiply)
     svr = TOPs;
     svl = TOPm1s;
 #ifdef PERL_PRESERVE_IVUV
-    SvIV_please_nomg(svr);
-    if (SvIOK(svr)) {
+    if (SvIV_please_nomg(svr)) {
 	/* Unless the left argument is integer in range we are going to have to
 	   use NV maths. Hence only attempt to coerce the right argument if
 	   we know the left is integer.  */
 	/* Left operand is defined, so is it IV? */
-	SvIV_please_nomg(svl);
-	if (SvIOK(svl)) {
+	if (SvIV_please_nomg(svl)) {
 	    bool auvok = SvUOK(svl);
 	    bool buvok = SvUOK(svr);
 	    const UV topmask = (~ (UV)0) << (4 * sizeof (UV));
@@ -1336,10 +1328,7 @@ PP(pp_divide)
 #endif
 
 #ifdef PERL_TRY_UV_DIVIDE
-    SvIV_please_nomg(svr);
-    if (SvIOK(svr)) {
-        SvIV_please_nomg(svl);
-        if (SvIOK(svl)) {
+    if (SvIV_please_nomg(svr) && SvIV_please_nomg(svl)) {
             bool left_non_neg = SvUOK(svl);
             bool right_non_neg = SvUOK(svr);
             UV left;
@@ -1414,8 +1403,7 @@ PP(pp_divide)
                     RETURN;
                 } /* tried integer divide but it was not an integer result */
             } /* else (PERL_ABS(result) < 1.0) or (both UVs in range for NV) */
-        } /* left wasn't SvIOK */
-    } /* right wasn't SvIOK */
+    } /* one operand wasn't SvIOK */
 #endif /* PERL_TRY_UV_DIVIDE */
     {
 	NV right = SvNV_nomg(svr);
@@ -1447,8 +1435,7 @@ PP(pp_modulo)
 	NV dleft  = 0.0;
 	SV * const svr = TOPs;
 	SV * const svl = TOPm1s;
-	SvIV_please_nomg(svr);
-        if (SvIOK(svr)) {
+        if (SvIV_please_nomg(svr)) {
             right_neg = !SvUOK(svr);
             if (!right_neg) {
                 right = SvUVX(svr);
@@ -1478,9 +1465,7 @@ PP(pp_modulo)
         /* At this point use_double is only true if right is out of range for
            a UV.  In range NV has been rounded down to nearest UV and
            use_double false.  */
-        SvIV_please_nomg(svl);
-	if (!use_double && SvIOK(svl)) {
-            if (SvIOK(svl)) {
+	if (!use_double && SvIV_please_nomg(svl)) {
                 left_neg = !SvUOK(svl);
                 if (!left_neg) {
                     left = SvUVX(svl);
@@ -1493,7 +1478,6 @@ PP(pp_modulo)
                         left = -aiv;
                     }
                 }
-            }
         }
 	else {
 	    dleft = SvNV_nomg(svl);
@@ -1708,8 +1692,7 @@ PP(pp_subtract)
 #ifdef PERL_PRESERVE_IVUV
     /* See comments in pp_add (in pp_hot.c) about Overflow, and how
        "bad things" happen if you rely on signed integers wrapping.  */
-    SvIV_please_nomg(svr);
-    if (SvIOK(svr)) {
+    if (SvIV_please_nomg(svr)) {
 	/* Unless the left argument is integer in range we are going to have to
 	   use NV maths. Hence only attempt to coerce the right argument if
 	   we know the left is integer.  */
@@ -1723,8 +1706,7 @@ PP(pp_subtract)
 	    /* left operand is undef, treat as zero.  */
 	} else {
 	    /* Left operand is defined, so is it IV? */
-	    SvIV_please_nomg(svl);
-	    if (SvIOK(svl)) {
+	    if (SvIV_please_nomg(svl)) {
 		if ((auvok = SvUOK(svl)))
 		    auv = SvUVX(svl);
 		else {
@@ -1952,11 +1934,8 @@ Perl_do_ncmp(pTHX_ SV* const left, SV * const right)
 
     PERL_ARGS_ASSERT_DO_NCMP;
 #ifdef PERL_PRESERVE_IVUV
-    SvIV_please_nomg(right);
     /* Fortunately it seems NaN isn't IOK */
-    if (SvIOK(right)) {
-	SvIV_please_nomg(left);
-	if (SvIOK(left)) {
+    if (SvIV_please_nomg(right) && SvIV_please_nomg(left)) {
 	    if (!SvUOK(left)) {
 		const IV leftiv = SvIVX(left);
 		if (!SvUOK(right)) {
@@ -1992,7 +1971,6 @@ Perl_do_ncmp(pTHX_ SV* const left, SV * const right)
 		}
 	    }
 	    /* NOTREACHED */
-	}
     }
 #endif
     {