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Make MIPS soft-fp preserve NaN payloads for NAN2008 [committed]
- From: Joseph Myers <joseph at codesourcery dot com>
- To: <libc-alpha at sourceware dot org>
- Date: Wed, 4 Jan 2017 17:16:13 +0000
- Subject: Make MIPS soft-fp preserve NaN payloads for NAN2008 [committed]
- Authentication-results: sourceware.org; auth=none
This corresponds to a patch applied to libgcc. In glibc it doesn't
actually affect much (only fma, I think).
The MIPS sfp-machine.h files have an _FP_CHOOSENAN implementation
which emulates hardware semantics of not preserving signaling NaN
payloads for an operation with two NaN arguments (although that
doesn't suffice to avoid sNaN payload preservation in any case with
just one NaN argument).
However, those are only hardware semantics in the legacy NaN case; in
the NAN2008 case, the architecture documentation says hardware
preserves payloads in such cases. Furthermore, this implementation
assumes legacy NaN semantics, so in the NAN2008 case the
implementation actually has the effect of preserving sNaN payloads but
not preserving qNaN payloads, when both should be preserved.
This patch fixes the code just to copy from the first argument.
Tested for mips64 soft-float. Committed.
2017-01-04 Joseph Myers <joseph@codesourcery.com>
* sysdeps/mips/mips32/sfp-machine.h (_FP_CHOOSENAN): Always
preserve NaN payload if [__mips_nan2008].
* sysdeps/mips/mips64/sfp-machine.h (_FP_CHOOSENAN): Likewise.
diff --git a/sysdeps/mips/mips32/sfp-machine.h b/sysdeps/mips/mips32/sfp-machine.h
index 4e23aa8..5215655 100644
--- a/sysdeps/mips/mips32/sfp-machine.h
+++ b/sysdeps/mips/mips32/sfp-machine.h
@@ -41,9 +41,20 @@
# define _FP_QNANNEGATEDP 1
#endif
+#ifdef __mips_nan2008
+/* NaN payloads should be preserved for NAN2008. */
+# define _FP_CHOOSENAN(fs, wc, R, X, Y, OP) \
+ do \
+ { \
+ R##_s = X##_s; \
+ _FP_FRAC_COPY_##wc (R, X); \
+ R##_c = FP_CLS_NAN; \
+ } \
+ while (0)
+#else
/* From my experiments it seems X is chosen unless one of the
NaNs is sNaN, in which case the result is NANSIGN/NANFRAC. */
-#define _FP_CHOOSENAN(fs, wc, R, X, Y, OP) \
+# define _FP_CHOOSENAN(fs, wc, R, X, Y, OP) \
do { \
if ((_FP_FRAC_HIGH_RAW_##fs(X) | \
_FP_FRAC_HIGH_RAW_##fs(Y)) & _FP_QNANBIT_##fs) \
@@ -58,6 +69,7 @@
} \
R##_c = FP_CLS_NAN; \
} while (0)
+#endif
#define FP_EX_INVALID (1 << 4)
#define FP_EX_DIVZERO (1 << 3)
diff --git a/sysdeps/mips/mips64/sfp-machine.h b/sysdeps/mips/mips64/sfp-machine.h
index 708afc7..35cc4dd 100644
--- a/sysdeps/mips/mips64/sfp-machine.h
+++ b/sysdeps/mips/mips64/sfp-machine.h
@@ -44,9 +44,20 @@
# define _FP_QNANNEGATEDP 1
#endif
+#ifdef __mips_nan2008
+/* NaN payloads should be preserved for NAN2008. */
+# define _FP_CHOOSENAN(fs, wc, R, X, Y, OP) \
+ do \
+ { \
+ R##_s = X##_s; \
+ _FP_FRAC_COPY_##wc (R, X); \
+ R##_c = FP_CLS_NAN; \
+ } \
+ while (0)
+#else
/* From my experiments it seems X is chosen unless one of the
NaNs is sNaN, in which case the result is NANSIGN/NANFRAC. */
-#define _FP_CHOOSENAN(fs, wc, R, X, Y, OP) \
+# define _FP_CHOOSENAN(fs, wc, R, X, Y, OP) \
do { \
if ((_FP_FRAC_HIGH_RAW_##fs(X) | \
_FP_FRAC_HIGH_RAW_##fs(Y)) & _FP_QNANBIT_##fs) \
@@ -61,6 +72,7 @@
} \
R##_c = FP_CLS_NAN; \
} while (0)
+#endif
#define _FP_DECL_EX fpu_control_t _fcw
--
Joseph S. Myers
joseph@codesourcery.com