[PATCH 23/48] MIPS: math-emu: Don't pass qNaNs through quieting handlers

["Maciej W. Rozycki" <macro@xxxxxxxxxxxxxx>]

Don't call the `ieee754sp_nanxcpt' and `ieee754dp_nanxcpt' sNaN quieting 
handlers for a qNaN supplied to floating-point format conversions or 
SQRT.S/SQRT.D instructions, or for a qNaN produced out of a negative 
operand supplied to SQRT.S/SQRT.D instructions.  Return the qNaN right 
away in these cases.

Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxxxxx>
---
linux-mips-emu-nanxcpt-qnan.diff
Index: linux/arch/mips/math-emu/dp_fsp.c
===================================================================
--- linux.orig/arch/mips/math-emu/dp_fsp.c	2015-04-03 04:57:50.206062000 +0100
+++ linux/arch/mips/math-emu/dp_fsp.c	2015-04-03 04:58:06.696244000 +0100
@@ -44,7 +44,7 @@ union ieee754dp ieee754dp_fsp(union ieee
 		return ieee754dp_nanxcpt(ieee754dp_indef());
 
 	case IEEE754_CLASS_QNAN:
-		return ieee754dp_nanxcpt(ieee754dp_nan_fsp(xs, xm));
+		return ieee754dp_nan_fsp(xs, xm);
 
 	case IEEE754_CLASS_INF:
 		return ieee754dp_inf(xs);
Index: linux/arch/mips/math-emu/dp_sqrt.c
===================================================================
--- linux.orig/arch/mips/math-emu/dp_sqrt.c	2015-04-03 04:57:13.570713000 +0100
+++ linux/arch/mips/math-emu/dp_sqrt.c	2015-04-03 04:58:06.699229000 +0100
@@ -44,7 +44,7 @@ union ieee754dp ieee754dp_sqrt(union iee
 	switch (xc) {
 	case IEEE754_CLASS_QNAN:
 		/* sqrt(Nan) = Nan */
-		return ieee754dp_nanxcpt(x);
+		return x;
 
 	case IEEE754_CLASS_SNAN:
 		ieee754_setcx(IEEE754_INVALID_OPERATION);
@@ -58,7 +58,7 @@ union ieee754dp ieee754dp_sqrt(union iee
 		if (xs) {
 			/* sqrt(-Inf) = Nan */
 			ieee754_setcx(IEEE754_INVALID_OPERATION);
-			return ieee754dp_nanxcpt(ieee754dp_indef());
+			return ieee754dp_indef();
 		}
 		/* sqrt(+Inf) = Inf */
 		return x;
@@ -71,7 +71,7 @@ union ieee754dp ieee754dp_sqrt(union iee
 		if (xs) {
 			/* sqrt(-x) = Nan */
 			ieee754_setcx(IEEE754_INVALID_OPERATION);
-			return ieee754dp_nanxcpt(ieee754dp_indef());
+			return ieee754dp_indef();
 		}
 		break;
 	}
Index: linux/arch/mips/math-emu/sp_fdp.c
===================================================================
--- linux.orig/arch/mips/math-emu/sp_fdp.c	2015-04-03 04:57:50.208062000 +0100
+++ linux/arch/mips/math-emu/sp_fdp.c	2015-04-03 04:58:06.701235000 +0100
@@ -50,7 +50,7 @@ union ieee754sp ieee754sp_fdp(union ieee
 		nan = ieee754sp_nan_fdp(xs, xm);
 		if (!ieee754sp_isnan(nan))
 			nan = ieee754sp_indef();
-		return ieee754sp_nanxcpt(nan);
+		return nan;
 
 	case IEEE754_CLASS_INF:
 		return ieee754sp_inf(xs);
Index: linux/arch/mips/math-emu/sp_sqrt.c
===================================================================
--- linux.orig/arch/mips/math-emu/sp_sqrt.c	2015-04-03 04:57:13.582698000 +0100
+++ linux/arch/mips/math-emu/sp_sqrt.c	2015-04-03 04:58:06.703246000 +0100
@@ -37,7 +37,7 @@ union ieee754sp ieee754sp_sqrt(union iee
 	switch (xc) {
 	case IEEE754_CLASS_QNAN:
 		/* sqrt(Nan) = Nan */
-		return ieee754sp_nanxcpt(x);
+		return x;
 
 	case IEEE754_CLASS_SNAN:
 		ieee754_setcx(IEEE754_INVALID_OPERATION);
@@ -51,7 +51,7 @@ union ieee754sp ieee754sp_sqrt(union iee
 		if (xs) {
 			/* sqrt(-Inf) = Nan */
 			ieee754_setcx(IEEE754_INVALID_OPERATION);
-			return ieee754sp_nanxcpt(ieee754sp_indef());
+			return ieee754sp_indef();
 		}
 		/* sqrt(+Inf) = Inf */
 		return x;
@@ -61,7 +61,7 @@ union ieee754sp ieee754sp_sqrt(union iee
 		if (xs) {
 			/* sqrt(-x) = Nan */
 			ieee754_setcx(IEEE754_INVALID_OPERATION);
-			return ieee754sp_nanxcpt(ieee754sp_indef());
+			return ieee754sp_indef();
 		}
 		break;
 	}