MIPS: math-emu: Reinstate sNaN quieting handlers

Revert the changes made by commit fdffbafb [Lots of FPU bug fixes from
Kjeld Borch Egevang.] to `ieee754sp_nanxcpt' and `ieee754dp_nanxcpt'
sNaN quieting handlers and their callers so that sNaN processing is done
within the handlers againg.  Pass the sNaN causing an IEEE 754 invalid
operation exception down to the relevant handler.  Pass the sNaN in `fs'
where two sNaNs are supplied to a binary operation.

Set the Invalid Operation FCSR exception bits in the quieting handlers
rather than at their call sites throughout.  Make the handlers exclusive
for sNaN processing.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9688/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/math-emu/dp_add.c

@@ -37,19 +37,20 @@ union ieee754dp ieee754dp_add(union ieee754dp x, union ieee754dp y)
 	FLUSHYDP;
 
 	switch (CLPAIR(xc, yc)) {
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
+		return ieee754dp_nanxcpt(y);
+
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
-		ieee754_setcx(IEEE754_INVALID_OPERATION);
-		return ieee754dp_nanxcpt(ieee754dp_indef());
+		return ieee754dp_nanxcpt(x);
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):

arch/mips/math-emu/dp_div.c

@@ -39,19 +39,20 @@ union ieee754dp ieee754dp_div(union ieee754dp x, union ieee754dp y)
 	FLUSHYDP;
 
 	switch (CLPAIR(xc, yc)) {
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
+		return ieee754dp_nanxcpt(y);
+
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
-		ieee754_setcx(IEEE754_INVALID_OPERATION);
-		return ieee754dp_nanxcpt(ieee754dp_indef());
+		return ieee754dp_nanxcpt(x);
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):

arch/mips/math-emu/dp_fsp.c

@@ -40,8 +40,7 @@ union ieee754dp ieee754dp_fsp(union ieee754sp x)
 
 	switch (xc) {
 	case IEEE754_CLASS_SNAN:
-		ieee754_setcx(IEEE754_INVALID_OPERATION);
-		return ieee754dp_nanxcpt(ieee754dp_indef());
+		return ieee754dp_nanxcpt(ieee754dp_nan_fsp(xs, xm));
 
 	case IEEE754_CLASS_QNAN:
 		return ieee754dp_nan_fsp(xs, xm);

arch/mips/math-emu/dp_mul.c

@@ -47,19 +47,20 @@ union ieee754dp ieee754dp_mul(union ieee754dp x, union ieee754dp y)
 	FLUSHYDP;
 
 	switch (CLPAIR(xc, yc)) {
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
+		return ieee754dp_nanxcpt(y);
+
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
-		ieee754_setcx(IEEE754_INVALID_OPERATION);
-		return ieee754dp_nanxcpt(ieee754dp_indef());
+		return ieee754dp_nanxcpt(x);
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):

arch/mips/math-emu/dp_sqrt.c

@@ -42,14 +42,13 @@ union ieee754dp ieee754dp_sqrt(union ieee754dp x)
 
 	/* x == INF or NAN? */
 	switch (xc) {
+	case IEEE754_CLASS_SNAN:
+		return ieee754dp_nanxcpt(x);
+
 	case IEEE754_CLASS_QNAN:
 		/* sqrt(Nan) = Nan */
 		return x;
 
-	case IEEE754_CLASS_SNAN:
-		ieee754_setcx(IEEE754_INVALID_OPERATION);
-		return ieee754dp_nanxcpt(ieee754dp_indef());
-
 	case IEEE754_CLASS_ZERO:
 		/* sqrt(0) = 0 */
 		return x;

arch/mips/math-emu/dp_sub.c

@@ -37,19 +37,20 @@ union ieee754dp ieee754dp_sub(union ieee754dp x, union ieee754dp y)
 	FLUSHYDP;
 
 	switch (CLPAIR(xc, yc)) {
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
+		return ieee754dp_nanxcpt(y);
+
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
-		ieee754_setcx(IEEE754_INVALID_OPERATION);
-		return ieee754dp_nanxcpt(ieee754dp_indef());
+		return ieee754dp_nanxcpt(x);
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):

arch/mips/math-emu/ieee754dp.c

@@ -42,18 +42,16 @@ static inline int ieee754dp_issnan(union ieee754dp x)
 }
 
 
+/*
+ * Raise the Invalid Operation IEEE 754 exception
+ * and convert the signaling NaN supplied to a quiet NaN.
+ */
 union ieee754dp __cold ieee754dp_nanxcpt(union ieee754dp r)
 {
-	assert(ieee754dp_isnan(r));
-
-	if (!ieee754dp_issnan(r))	/* QNAN does not cause invalid op !! */
-		return r;
-
-	/* If not enabled convert to a quiet NaN.  */
-	if (!ieee754_setandtestcx(IEEE754_INVALID_OPERATION))
-		return ieee754dp_indef();
+	assert(ieee754dp_issnan(r));
 
-	return r;
+	ieee754_setcx(IEEE754_INVALID_OPERATION);
+	return ieee754dp_indef();
 }
 
 static u64 ieee754dp_get_rounding(int sn, u64 xm)

arch/mips/math-emu/ieee754sp.c

@@ -42,18 +42,16 @@ static inline int ieee754sp_issnan(union ieee754sp x)
 }
 
 
+/*
+ * Raise the Invalid Operation IEEE 754 exception
+ * and convert the signaling NaN supplied to a quiet NaN.
+ */
 union ieee754sp __cold ieee754sp_nanxcpt(union ieee754sp r)
 {
-	assert(ieee754sp_isnan(r));
-
-	if (!ieee754sp_issnan(r))	/* QNAN does not cause invalid op !! */
-		return r;
-
-	/* If not enabled convert to a quiet NaN.  */
-	if (!ieee754_setandtestcx(IEEE754_INVALID_OPERATION))
-		return ieee754sp_indef();
+	assert(ieee754sp_issnan(r));
 
-	return r;
+	ieee754_setcx(IEEE754_INVALID_OPERATION);
+	return ieee754sp_indef();
 }
 
 static unsigned ieee754sp_get_rounding(int sn, unsigned xm)

arch/mips/math-emu/sp_add.c

@@ -37,19 +37,20 @@ union ieee754sp ieee754sp_add(union ieee754sp x, union ieee754sp y)
 	FLUSHYSP;
 
 	switch (CLPAIR(xc, yc)) {
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
+		return ieee754sp_nanxcpt(y);
+
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
-		ieee754_setcx(IEEE754_INVALID_OPERATION);
-		return ieee754sp_nanxcpt(ieee754sp_indef());
+		return ieee754sp_nanxcpt(x);
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):

arch/mips/math-emu/sp_div.c

@@ -39,19 +39,20 @@ union ieee754sp ieee754sp_div(union ieee754sp x, union ieee754sp y)
 	FLUSHYSP;
 
 	switch (CLPAIR(xc, yc)) {
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
+		return ieee754sp_nanxcpt(y);
+
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
-		ieee754_setcx(IEEE754_INVALID_OPERATION);
-		return ieee754sp_nanxcpt(ieee754sp_indef());
+		return ieee754sp_nanxcpt(x);
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):

arch/mips/math-emu/sp_fdp.c

@@ -43,8 +43,7 @@ union ieee754sp ieee754sp_fdp(union ieee754dp x)
 
 	switch (xc) {
 	case IEEE754_CLASS_SNAN:
-		ieee754_setcx(IEEE754_INVALID_OPERATION);
-		return ieee754sp_nanxcpt(ieee754sp_indef());
+		return ieee754sp_nanxcpt(ieee754sp_nan_fdp(xs, xm));
 
 	case IEEE754_CLASS_QNAN:
 		nan = ieee754sp_nan_fdp(xs, xm);

arch/mips/math-emu/sp_mul.c

@@ -47,19 +47,20 @@ union ieee754sp ieee754sp_mul(union ieee754sp x, union ieee754sp y)
 	FLUSHYSP;
 
 	switch (CLPAIR(xc, yc)) {
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
+		return ieee754sp_nanxcpt(y);
+
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
-		ieee754_setcx(IEEE754_INVALID_OPERATION);
-		return ieee754sp_nanxcpt(ieee754sp_indef());
+		return ieee754sp_nanxcpt(x);
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):

arch/mips/math-emu/sp_sqrt.c

@@ -35,14 +35,13 @@ union ieee754sp ieee754sp_sqrt(union ieee754sp x)
 
 	/* x == INF or NAN? */
 	switch (xc) {
+	case IEEE754_CLASS_SNAN:
+		return ieee754sp_nanxcpt(x);
+
 	case IEEE754_CLASS_QNAN:
 		/* sqrt(Nan) = Nan */
 		return x;
 
-	case IEEE754_CLASS_SNAN:
-		ieee754_setcx(IEEE754_INVALID_OPERATION);
-		return ieee754sp_nanxcpt(ieee754sp_indef());
-
 	case IEEE754_CLASS_ZERO:
 		/* sqrt(0) = 0 */
 		return x;

arch/mips/math-emu/sp_sub.c

@@ -37,19 +37,20 @@ union ieee754sp ieee754sp_sub(union ieee754sp x, union ieee754sp y)
 	FLUSHYSP;
 
 	switch (CLPAIR(xc, yc)) {
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
+		return ieee754sp_nanxcpt(y);
+
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
 	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
-		ieee754_setcx(IEEE754_INVALID_OPERATION);
-		return ieee754sp_nanxcpt(ieee754sp_indef());
+		return ieee754sp_nanxcpt(x);
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):