target/m68k: Explicitly set 2-NaN propagation rule

Explicitly set the 2-NaN propagation rule on env->fp_status
and on the temporary fp_status that we use in frem (since
we pass that to a division operation function).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

2 files changed, 17 insertions, 0 deletions

diff --git a/target/m68k/cpu.c b/target/m68k/cpu.c
index 1d49f4cb23..5fe335558a 100644
--- a/target/m68k/cpu.c
+++ b/target/m68k/cpu.c
@@ -93,6 +93,22 @@ static void m68k_cpu_reset_hold(Object *obj, ResetType type)
         env->fregs[i].d = nan;
     }
     cpu_m68k_set_fpcr(env, 0);
+    /*
+     * M68000 FAMILY PROGRAMMER'S REFERENCE MANUAL
+     * 3.4 FLOATING-POINT INSTRUCTION DETAILS
+     * If either operand, but not both operands, of an operation is a
+     * nonsignaling NaN, then that NaN is returned as the result. If both
+     * operands are nonsignaling NaNs, then the destination operand
+     * nonsignaling NaN is returned as the result.
+     * If either operand to an operation is a signaling NaN (SNaN), then the
+     * SNaN bit is set in the FPSR EXC byte. If the SNaN exception enable bit
+     * is set in the FPCR ENABLE byte, then the exception is taken and the
+     * destination is not modified. If the SNaN exception enable bit is not
+     * set, setting the SNaN bit in the operand to a one converts the SNaN to
+     * a nonsignaling NaN. The operation then continues as described in the
+     * preceding paragraph for nonsignaling NaNs.
+     */
+    set_float_2nan_prop_rule(float_2nan_prop_ab, &env->fp_status);
     env->fpsr = 0;
 
     /* TODO: We should set PC from the interrupt vector.  */
diff --git a/target/m68k/fpu_helper.c b/target/m68k/fpu_helper.c
index 8314791f50..a605162b71 100644
--- a/target/m68k/fpu_helper.c
+++ b/target/m68k/fpu_helper.c
@@ -620,6 +620,7 @@ void HELPER(frem)(CPUM68KState *env, FPReg *res, FPReg *val0, FPReg *val1)
         int sign;
 
         /* Calculate quotient directly using round to nearest mode */
+        set_float_2nan_prop_rule(float_2nan_prop_ab, &fp_status);
         set_float_rounding_mode(float_round_nearest_even, &fp_status);
         set_floatx80_rounding_precision(
             get_floatx80_rounding_precision(&env->fp_status), &fp_status);