[PATCH] math-emu: Add support for reporting exact invalid exception

[Kumar Gala]

Some architectures (like powerpc) provide status information on the exact
type of invalid exception.  This is pretty straight forward as we already
report invalid exceptions via FP_SET_EXCEPTION.

We add new flags (FP_EX_INVALID_*) the architecture code can define if it
wants the exact invalid exception reported.

We had to split out the INF/INF and 0/0 cases for divide to allow reporting
the two invalid forms properly.

Signed-off-by: Kumar Gala <galak at kernel.crashing.org>
---
I intend these patches to go via the powerpc.git tree if no one has issues.

- k

 include/math-emu/op-common.h |   12 ++++++++----
 include/math-emu/soft-fp.h   |   19 +++++++++++++++++++
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/include/math-emu/op-common.h b/include/math-emu/op-common.h
index bb46e76..cc1ec39 100644
--- a/include/math-emu/op-common.h
+++ b/include/math-emu/op-common.h
@@ -73,7 +73,7 @@ do {									\
 	X##_c = FP_CLS_NAN;						\
 	/* Check for signaling NaN */					\
 	if (!(_FP_FRAC_HIGH_RAW_##fs(X) & _FP_QNANBIT_##fs))		\
-	  FP_SET_EXCEPTION(FP_EX_INVALID);				\
+	  FP_SET_EXCEPTION(FP_EX_INVALID | FP_EX_INVALID_SNAN);		\
       }									\
     break;								\
   }									\
@@ -324,7 +324,7 @@ do {									     \
 	_FP_FRAC_SET_##wc(R, _FP_NANFRAC_##fs);				     \
 	R##_s = _FP_NANSIGN_##fs;					     \
 	R##_c = FP_CLS_NAN;						     \
-	FP_SET_EXCEPTION(FP_EX_INVALID);				     \
+	FP_SET_EXCEPTION(FP_EX_INVALID | FP_EX_INVALID_ISI);		     \
 	break;								     \
       }									     \
     /* FALLTHRU */							     \
@@ -431,7 +431,7 @@ do {							\
     R##_s = _FP_NANSIGN_##fs;				\
     R##_c = FP_CLS_NAN;					\
     _FP_FRAC_SET_##wc(R, _FP_NANFRAC_##fs);		\
-    FP_SET_EXCEPTION(FP_EX_INVALID);			\
+    FP_SET_EXCEPTION(FP_EX_INVALID | FP_EX_INVALID_IMZ);\
     break;						\
 							\
   default:						\
@@ -490,11 +490,15 @@ do {							\
     break;						\
 							\
   case _FP_CLS_COMBINE(FP_CLS_INF,FP_CLS_INF):		\
+    R##_s = _FP_NANSIGN_##fs;				\
+    R##_c = FP_CLS_NAN;					\
+    _FP_FRAC_SET_##wc(R, _FP_NANFRAC_##fs);		\
+    FP_SET_EXCEPTION(FP_EX_INVALID | FP_EX_INVALID_IDI);\
   case _FP_CLS_COMBINE(FP_CLS_ZERO,FP_CLS_ZERO):	\
     R##_s = _FP_NANSIGN_##fs;				\
     R##_c = FP_CLS_NAN;					\
     _FP_FRAC_SET_##wc(R, _FP_NANFRAC_##fs);		\
-    FP_SET_EXCEPTION(FP_EX_INVALID);			\
+    FP_SET_EXCEPTION(FP_EX_INVALID | FP_EX_INVALID_ZDZ);\
     break;						\
 							\
   default:						\
diff --git a/include/math-emu/soft-fp.h b/include/math-emu/soft-fp.h
index a6f873b..3f284bc 100644
--- a/include/math-emu/soft-fp.h
+++ b/include/math-emu/soft-fp.h
@@ -51,6 +51,25 @@
 #ifndef FP_EX_INVALID
 #define FP_EX_INVALID		0
 #endif
+#ifndef FP_EX_INVALID_SNAN
+#define FP_EX_INVALID_SNAN	0
+#endif
+/* inf - inf */
+#ifndef FP_EX_INVALID_ISI
+#define FP_EX_INVALID_ISI	0
+#endif
+/* inf / inf */
+#ifndef FP_EX_INVALID_IDI
+#define FP_EX_INVALID_IDI	0
+#endif
+/* 0 / 0 */
+#ifndef FP_EX_INVALID_ZDZ
+#define FP_EX_INVALID_ZDZ	0
+#endif
+/* inf * 0 */
+#ifndef FP_EX_INVALID_IMZ
+#define FP_EX_INVALID_IMZ	0
+#endif
 #ifndef FP_EX_OVERFLOW
 #define FP_EX_OVERFLOW		0
 #endif
-- 
1.5.5.1