target/hppa: Explicitly set 2-NaN propagation rule

Set the 2-NaN propagation rule explicitly in env->fp_status.

Really we only need to do this at CPU reset (after reset has zeroed
out most of the CPU state struct, which typically includes fp_status
fields).  However target/hppa does not currently implement CPU reset
at all, so leave a TODO comment to note that this could be moved if
we ever do implement reset.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20241025141254.2141506-7-peter.maydell@linaro.org

fpu/softfloat-specialize.c.inc

@@ -403,9 +403,9 @@ static int pickNaN(FloatClass a_cls, FloatClass b_cls,
 #if defined(TARGET_AVR) || defined(TARGET_HEXAGON) \
     || defined(TARGET_RISCV) || defined(TARGET_SH4) \
     || defined(TARGET_TRICORE) || defined(TARGET_ARM) || defined(TARGET_MIPS) \
-    || defined(TARGET_LOONGARCH64)
+    || defined(TARGET_LOONGARCH64) || defined(TARGET_HPPA)
         g_assert_not_reached();
-#elif defined(TARGET_HPPA) || defined(TARGET_S390X)
+#elif defined(TARGET_S390X)
         rule = float_2nan_prop_s_ab;
 #elif defined(TARGET_PPC) || defined(TARGET_M68K)
         /*

target/hppa/fpu_helper.c

@@ -49,6 +49,12 @@ void HELPER(loaded_fr0)(CPUHPPAState *env)
     d = FIELD_EX32(shadow, FPSR, D);
     set_flush_to_zero(d, &env->fp_status);
     set_flush_inputs_to_zero(d, &env->fp_status);
+
+    /*
+     * TODO: we only need to do this at CPU reset, but currently
+     * HPPA does note implement a CPU reset method at all...
+     */
+    set_float_2nan_prop_rule(float_2nan_prop_s_ab, &env->fp_status);
 }
 
 void cpu_hppa_loaded_fr0(CPUHPPAState *env)