Commit fdffbafb [Lots of FPU bug fixes from Kjeld Borch Egevang.]
replaced the two single `ieee754sp_nanxcpt' and `ieee754dp_nanxcpt'
places, where sNaN quieting used to happen for single and double
floating-point operations respectively, with individual qNaN
instantiations across all the call sites instead. It also made most of
these two functions dead code as where called on a qNaN they return
right away.
To revert the damage and make sNaN quieting uniform again first rewrite
`ieee754sp_nanxcpt' and `ieee754dp_nanxcpt' to do the same quieting all
the call sites do, that is return the default qNaN encoding for all
input sNaN values; never propagate any sNaN payload bits from its
trailing significand field.
Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxxxxx>
---
linux-mips-emu-nanxcpt-snan.diff
Index: linux/arch/mips/math-emu/ieee754dp.c
===================================================================
--- linux.orig/arch/mips/math-emu/ieee754dp.c 2015-04-02 20:18:51.033516000 +0100
+++ linux/arch/mips/math-emu/ieee754dp.c 2015-04-02 20:27:54.976193000 +0100
@@ -49,14 +49,9 @@ union ieee754dp __cold ieee754dp_nanxcpt
if (!ieee754dp_issnan(r)) /* QNAN does not cause invalid op !! */
return r;
- if (!ieee754_setandtestcx(IEEE754_INVALID_OPERATION)) {
- /* not enabled convert to a quiet NaN */
- DPMANT(r) &= (~DP_MBIT(DP_FBITS-1));
- if (ieee754dp_isnan(r))
- return r;
- else
- return ieee754dp_indef();
- }
+ /* If not enabled convert to a quiet NaN. */
+ if (!ieee754_setandtestcx(IEEE754_INVALID_OPERATION))
+ return ieee754dp_indef();
return r;
}
Index: linux/arch/mips/math-emu/ieee754sp.c
===================================================================
--- linux.orig/arch/mips/math-emu/ieee754sp.c 2015-04-02 20:18:51.036515000 +0100
+++ linux/arch/mips/math-emu/ieee754sp.c 2015-04-02 20:27:54.979190000 +0100
@@ -49,14 +49,9 @@ union ieee754sp __cold ieee754sp_nanxcpt
if (!ieee754sp_issnan(r)) /* QNAN does not cause invalid op !! */
return r;
- if (!ieee754_setandtestcx(IEEE754_INVALID_OPERATION)) {
- /* not enabled convert to a quiet NaN */
- SPMANT(r) &= (~SP_MBIT(SP_FBITS-1));
- if (ieee754sp_isnan(r))
- return r;
- else
- return ieee754sp_indef();
- }
+ /* If not enabled convert to a quiet NaN. */
+ if (!ieee754_setandtestcx(IEEE754_INVALID_OPERATION))
+ return ieee754sp_indef();
return r;
}
