math: raise invalid flag in ilogb*.c on +-0, +-inf and nan

src/math/ilogb.c

@@ -8,13 +8,17 @@ int ilogb(double x)
 
 	if (!e) {
 		u.bits <<= 12;
-		if (u.bits == 0)
+		if (u.bits == 0) {
+			FORCE_EVAL(0/0.0f);
 			return FP_ILOGB0;
+		}
 		/* subnormal x */
 		for (e = -0x3ff; u.bits < (uint64_t)1<<63; e--, u.bits<<=1);
 		return e;
 	}
-	if (e == 0x7ff)
+	if (e == 0x7ff) {
+		FORCE_EVAL(0/0.0f);
 		return u.bits<<12 ? FP_ILOGBNAN : INT_MAX;
+	}
 	return e - 0x3ff;
 }

src/math/ilogbf.c

@@ -8,13 +8,17 @@ int ilogbf(float x)
 
 	if (!e) {
 		u.bits <<= 9;
-		if (u.bits == 0)
+		if (u.bits == 0) {
+			FORCE_EVAL(0/0.0f);
 			return FP_ILOGB0;
+		}
 		/* subnormal x */
 		for (e = -0x7f; u.bits < (uint32_t)1<<31; e--, u.bits<<=1);
 		return e;
 	}
-	if (e == 0xff)
+	if (e == 0xff) {
+		FORCE_EVAL(0/0.0f);
 		return u.bits<<9 ? FP_ILOGBNAN : INT_MAX;
+	}
 	return e - 0x7f;
 }

src/math/ilogbl.c

@@ -14,15 +14,19 @@ int ilogbl(long double x)
 	int e = u.bits.exp;
 
 	if (!e) {
-		if (m == 0)
+		if (m == 0) {
+			FORCE_EVAL(0/0.0f);
 			return FP_ILOGB0;
+		}
 		/* subnormal x */
 		for (e = -0x3fff+1; m < (uint64_t)1<<63; e--, m<<=1);
 		return e;
 	}
-	if (e == 0x7fff)
+	if (e == 0x7fff) {
+		FORCE_EVAL(0/0.0f);
 		/* in ld80 msb is set in inf */
 		return m & (uint64_t)-1>>1 ? FP_ILOGBNAN : INT_MAX;
+	}
 	return e - 0x3fff;
 }
 #endif