[PATCH v3 3/4] sim: Add partial support for IEEE 754-2008

Dragan Mladjenovic
2022-01-11T21:25:27Z

From: Faraz Shahbazker <fshahbazker@wavecomp.com>

2022-01-11 Faraz Shahbazker <fshahbazker@wavecomp.com>

sim/common/ChangeLog:
* sim-fpu.c (sim_fpu_minmax_nan): New.
(sim_fpu_max): Add variant behaviour for IEEE 754-2008.
(sim_fpu_min): Likewise.
(sim_fpu_is_un, sim_fpu_is_or): New.
(sim_fpu_un, sim_fpu_or): New.
(sim_fpu_current_mode): New.
(sim_fpu_is_ieee754_2008, sim_fpu_is_ieee754_1985): New.
(sim_fpu_set_mode): New.
(sim_fpu_classify): New.
* sim-fpu.h (sim_fpu_minmax_nan): New declaration.
(sim_fpu_un, sim_fpu_or): New declarations.
(sim_fpu_is_un, sim_fpu_is_or): New declarations.
(sim_fpu_mode): New.
(sim_fpu_is_ieee754_2008): New declaration.
(sim_fpu_is_ieee754_1985): New declaration.
(sim_fpu_set_mode): New declaration.
(sim_fpu_classify): New declaration.
---
sim/common/sim-fpu.c | 125 +++++++++++++++++++++++++++++++++++++++++--
sim/common/sim-fpu.h | 19 ++++++-
2 files changed, 139 insertions(+), 5 deletions(-)

Changes from v2: Fix Werror failures.

diff --git a/sim/common/sim-fpu.c b/sim/common/sim-fpu.c
index 9e6abf01391..3559d474fed 100644
--- a/sim/common/sim-fpu.c
+++ b/sim/common/sim-fpu.c
@@ -1005,6 +1005,30 @@ sim_fpu_op_nan (sim_fpu *f, const sim_fpu *l, const sim_fpu *r)
return 0;
}

+/* NaN handling specific to min/max operations. */
+
+INLINE_SIM_FPU (int)
+sim_fpu_minmax_nan (sim_fpu *f, const sim_fpu *l, const sim_fpu *r)
+{
+ if (sim_fpu_is_snan (l)
+ || sim_fpu_is_snan (r)
+ || sim_fpu_is_ieee754_1985 ())
+ return sim_fpu_op_nan (f, l, r);
+ else
+ /* if sim_fpu_is_ieee754_2008()
+ && ((sim_fpu_is_qnan (l) || sim_fpu_is_qnan (r))) */
+ {
+ /* In IEEE754-2008:
+ * "minNum/maxNum is ... the canonicalized number if one
+ * operand is a number and the other a quiet NaN." */
+ if (sim_fpu_is_qnan (l))
+ *f = *r;
+ else /* if (sim_fpu_is_qnan (r)) */
+ *f = *l;
+ return 0;
+ }
+}
+
/* Arithmetic ops */

INLINE_SIM_FPU (int)
@@ -1553,7 +1577,7 @@ sim_fpu_max (sim_fpu *f,
const sim_fpu *r)
{
if (sim_fpu_is_nan (l) || sim_fpu_is_nan (r))
- return sim_fpu_op_nan (f, l, r);
+ return sim_fpu_minmax_nan (f, l, r);
if (sim_fpu_is_infinity (l))
{
if (sim_fpu_is_infinity (r)
@@ -1616,7 +1640,7 @@ sim_fpu_min (sim_fpu *f,
const sim_fpu *r)
{
if (sim_fpu_is_nan (l) || sim_fpu_is_nan (r))
- return sim_fpu_op_nan (f, l, r);
+ return sim_fpu_minmax_nan (f, l, r);
if (sim_fpu_is_infinity (l))
{
if (sim_fpu_is_infinity (r)
@@ -1677,7 +1701,7 @@ INLINE_SIM_FPU (int)
sim_fpu_neg (sim_fpu *f,
const sim_fpu *r)
{
- if (sim_fpu_is_snan (r))
+ if (sim_fpu_is_ieee754_1985 () && sim_fpu_is_snan (r))
{
*f = *r;
f->class = sim_fpu_class_qnan;
@@ -1700,7 +1724,7 @@ sim_fpu_abs (sim_fpu *f,
{
*f = *r;
f->sign = 0;
- if (sim_fpu_is_snan (r))
+ if (sim_fpu_is_ieee754_1985 () && sim_fpu_is_snan (r))
{
f->class = sim_fpu_class_qnan;
return sim_fpu_status_invalid_snan;
@@ -2255,6 +2279,23 @@ sim_fpu_is_gt (const sim_fpu *l, const sim_fpu *r)
return is;
}

+INLINE_SIM_FPU (int)
+sim_fpu_is_un (const sim_fpu *l,
+ const sim_fpu *r)
+{
+ int is;
+ sim_fpu_un (&is, l, r);
+ return is;
+}
+
+INLINE_SIM_FPU (int)
+sim_fpu_is_or (const sim_fpu *l,
+ const sim_fpu *r)
+{
+ int is;
+ sim_fpu_or (&is, l, r);
+ return is;
+}

/* Compare operators */

@@ -2378,10 +2419,68 @@ sim_fpu_gt (int *is,
return sim_fpu_lt (is, r, l);
}

+INLINE_SIM_FPU (int)
+sim_fpu_un (int *is, const sim_fpu *l, const sim_fpu *r)
+{
+ if (sim_fpu_is_nan (l) || sim_fpu_is_nan (r))
+ {
+ *is = 1;
+ return 0;
+ }
+
+ *is = 0;
+ return 0;
+}
+
+INLINE_SIM_FPU (int)
+sim_fpu_or (int *is, const sim_fpu *l, const sim_fpu *r)
+{
+ sim_fpu_un (is, l, r);
+
+ /* Invert result. */
+ *is = !*is;
+ return 0;
+}
+
+INLINE_SIM_FPU(int)
+sim_fpu_classify (const sim_fpu *f)
+{
+ switch (f->class)
+ {
+ case sim_fpu_class_snan: return SIM_FPU_IS_SNAN;
+ case sim_fpu_class_qnan: return SIM_FPU_IS_QNAN;
+ case sim_fpu_class_infinity:
+ if (!f->sign)
+ return SIM_FPU_IS_PINF;
+ else
+ return SIM_FPU_IS_NINF;
+ case sim_fpu_class_zero:
+ if (!f->sign)
+ return SIM_FPU_IS_PZERO;
+ else
+ return SIM_FPU_IS_NZERO;
+ case sim_fpu_class_number:
+ if (!f->sign)
+ return SIM_FPU_IS_PNUMBER;
+ else
+ return SIM_FPU_IS_NNUMBER;
+ case sim_fpu_class_denorm:
+ if (!f->sign)
+ return SIM_FPU_IS_PDENORM;
+ else
+ return SIM_FPU_IS_NDENORM;
+ default:
+ fprintf (stderr, "Bad switch\n");
+ abort ();
+ }
+ return 0;
+}

/* A number of useful constants */

#if EXTERN_SIM_FPU_P
+static sim_fpu_mode sim_fpu_current_mode = sim_fpu_ieee754_1985;
+
const sim_fpu sim_fpu_zero = {
sim_fpu_class_zero, 0, 0, 0
};
@@ -2410,6 +2509,24 @@ const sim_fpu sim_fpu_max64 = {
bool sim_fpu_quiet_nan_inverted = false;
#endif

+/* Specification swapping behaviour */
+INLINE_SIM_FPU (bool)
+sim_fpu_is_ieee754_1985 (void)
+{
+ return (sim_fpu_current_mode == sim_fpu_ieee754_1985);
+}
+
+INLINE_SIM_FPU (bool)
+sim_fpu_is_ieee754_2008 (void)
+{
+ return (sim_fpu_current_mode == sim_fpu_ieee754_2008);
+}
+
+INLINE_SIM_FPU (void)
+sim_fpu_set_mode (const sim_fpu_mode m)
+{
+ sim_fpu_current_mode = m;
+}

/* For debugging */

diff --git a/sim/common/sim-fpu.h b/sim/common/sim-fpu.h
index 34a56efae22..c84b35811e9 100644
--- a/sim/common/sim-fpu.h
+++ b/sim/common/sim-fpu.h
@@ -252,6 +252,8 @@ INLINE_SIM_FPU (int) sim_fpu_sqrt (sim_fpu *f,

INLINE_SIM_FPU (int) sim_fpu_op_nan (sim_fpu *f,
const sim_fpu *l, const sim_fpu *r);
+INLINE_SIM_FPU (int) sim_fpu_minmax_nan (sim_fpu *f,
+ const sim_fpu *l, const sim_fpu *r);

@@ -302,7 +304,8 @@ INLINE_SIM_FPU (double) sim_fpu_2d (const sim_fpu *d);
/* INLINE_SIM_FPU (void) sim_fpu_f2 (sim_fpu *f, float s); */
INLINE_SIM_FPU (void) sim_fpu_d2 (sim_fpu *f, double d);

-
+/* IEEE754-2008 classifiction function. */
+INLINE_SIM_FPU (int) sim_fpu_classify (const sim_fpu *f);

/* Specific number classes.

@@ -343,6 +346,8 @@ INLINE_SIM_FPU (int) sim_fpu_eq (int *is, const sim_fpu *l, const sim_fpu *r);
INLINE_SIM_FPU (int) sim_fpu_ne (int *is, const sim_fpu *l, const sim_fpu *r);
INLINE_SIM_FPU (int) sim_fpu_ge (int *is, const sim_fpu *l, const sim_fpu *r);
INLINE_SIM_FPU (int) sim_fpu_gt (int *is, const sim_fpu *l, const sim_fpu *r);
+INLINE_SIM_FPU (int) sim_fpu_un (int *is, const sim_fpu *l, const sim_fpu *r);
+INLINE_SIM_FPU (int) sim_fpu_or (int *is, const sim_fpu *l, const sim_fpu *r);

INLINE_SIM_FPU (int) sim_fpu_is_lt (const sim_fpu *l, const sim_fpu *r);
INLINE_SIM_FPU (int) sim_fpu_is_le (const sim_fpu *l, const sim_fpu *r);
@@ -350,8 +355,20 @@ INLINE_SIM_FPU (int) sim_fpu_is_eq (const sim_fpu *l, const sim_fpu *r);
INLINE_SIM_FPU (int) sim_fpu_is_ne (const sim_fpu *l, const sim_fpu *r);
INLINE_SIM_FPU (int) sim_fpu_is_ge (const sim_fpu *l, const sim_fpu *r);
INLINE_SIM_FPU (int) sim_fpu_is_gt (const sim_fpu *l, const sim_fpu *r);
+INLINE_SIM_FPU (int) sim_fpu_is_un (const sim_fpu *l, const sim_fpu *r);
+INLINE_SIM_FPU (int) sim_fpu_is_or (const sim_fpu *l, const sim_fpu *r);

+/* Changes the behaviour of the library to IEEE754-2008 or IEEE754-1985.
+ * The default for the library is IEEE754-1985. */
+typedef enum
+{
+ sim_fpu_ieee754_1985,
+ sim_fpu_ieee754_2008,
+} sim_fpu_mode;

+INLINE_SIM_FPU (bool) sim_fpu_is_ieee754_1985 (void);
+INLINE_SIM_FPU (bool) sim_fpu_is_ieee754_2008 (void);
+INLINE_SIM_FPU (void) sim_fpu_set_mode (const sim_fpu_mode m);

/* General number class and comparison operators.

--
2.17.1