[OpenRISC] [PATCH v2 3/5] or1k: Support for softfloat to emulate hw exceptions

Stafford Horne
2021-01-13T23:50:30Z

This allows the openrisc softfloat implementation to set exceptions.
This also sets the correct tininess after rounding value to be
consistent with hardware and simulator implementations.

libgcc/ChangeLog:

* config/or1k/sfp-machine.h (FP_RND_NEAREST, FP_RND_ZERO,
FP_RND_PINF, FP_RND_MINF, FP_RND_MASK, FP_EX_OVERFLOW,
FP_EX_UNDERFLOW, FP_EX_INEXACT, FP_EX_INVALID, FP_EX_DIVZERO,
FP_EX_ALL): New constant macros.
(_FP_DECL_EX, FP_ROUNDMODE, FP_INIT_ROUNDMODE,
FP_HANDLE_EXCEPTIONS): New macros.
(_FP_TININESS_AFTER_ROUNDING): Change to 1.
---
libgcc/config/or1k/sfp-machine.h | 41 +++++++++++++++++++++++++++++++-
1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/libgcc/config/or1k/sfp-machine.h b/libgcc/config/or1k/sfp-machine.h
index 5da9e84990d..eebe5b0578e 100644
--- a/libgcc/config/or1k/sfp-machine.h
+++ b/libgcc/config/or1k/sfp-machine.h
@@ -41,12 +41,51 @@
R##_c = FP_CLS_NAN; \
} while (0)

+/* Handle getting and setting rounding mode for soft fp operations. */
+
+#define FP_RND_NEAREST (0x0 << 1)
+#define FP_RND_ZERO (0x1 << 1)
+#define FP_RND_PINF (0x2 << 1)
+#define FP_RND_MINF (0x3 << 1)
+#define FP_RND_MASK (0x3 << 1)
+
+#define FP_EX_OVERFLOW 1 << 3
+#define FP_EX_UNDERFLOW 1 << 4
+#define FP_EX_INEXACT 1 << 8
+#define FP_EX_INVALID 1 << 9
+#define FP_EX_DIVZERO 1 << 11
+#define FP_EX_ALL \
+ (FP_EX_INVALID | FP_EX_DIVZERO | FP_EX_OVERFLOW | FP_EX_UNDERFLOW \
+ | FP_EX_INEXACT)
+
+#define _FP_DECL_EX \
+ unsigned int _fpcsr __attribute__ ((unused)) = FP_RND_NEAREST
+
+#define FP_ROUNDMODE (_fpcsr & FP_RND_MASK)
+
+#ifdef __or1k_hard_float__
+#define FP_INIT_ROUNDMODE \
+do { \
+ __asm__ volatile ("l.mfspr %0,r0,20" : "=r" (_fpcsr)); \
+} while (0)
+
+#define FP_HANDLE_EXCEPTIONS \
+do { \
+ if (__builtin_expect (_fex, 0)) \
+ { \
+ _fpcsr &= ~FP_EX_ALL; \
+ _fpcsr |= _fex; \
+ __asm__ volatile ("l.mtspr r0,%0,20" : : "r" (_fpcsr)); \
+ } \
+} while (0)
+#endif
+
#define __LITTLE_ENDIAN 1234
#define __BIG_ENDIAN 4321

#define __BYTE_ORDER __BIG_ENDIAN

-#define _FP_TININESS_AFTER_ROUNDING 0
+#define _FP_TININESS_AFTER_ROUNDING 1

/* Define ALIASNAME as a strong alias for NAME. */
# define strong_alias(name, aliasname) _strong_alias(name, aliasname)
--
2.26.2