softfloat: Set 2-NaN propagation rule in float_status, not at compile time

[PATCH 08/21] target/ppc: Explicitly set 2-NaN propagation rule

Posted by Peter Maydell 4 weeks, 1 day ago

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

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
As an aside, it looks a bit suspicious that we set
tininess_before_rounding on fp_status but not vec_status...
---
 target/ppc/cpu_init.c          |  8 ++++++++
 fpu/softfloat-specialize.c.inc | 10 ++--------
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/target/ppc/cpu_init.c b/target/ppc/cpu_init.c
index 23881d09e9f..5c9dcd1f857 100644
--- a/target/ppc/cpu_init.c
+++ b/target/ppc/cpu_init.c
@@ -7326,6 +7326,14 @@ static void ppc_cpu_reset_hold(Object *obj, ResetType type)
     /* tininess for underflow is detected before rounding */
     set_float_detect_tininess(float_tininess_before_rounding,
                               &env->fp_status);
+    /*
+     * PowerPC propagation rules:
+     *  1. A if it sNaN or qNaN
+     *  2. B if it sNaN or qNaN
+     * A signaling NaN is always silenced before returning it.
+     */
+    set_float_2nan_prop_rule(float_2nan_prop_ab, &env->fp_status);
+    set_float_2nan_prop_rule(float_2nan_prop_ab, &env->vec_status);
 
     for (i = 0; i < ARRAY_SIZE(env->spr_cb); i++) {
         ppc_spr_t *spr = &env->spr_cb[i];
diff --git a/fpu/softfloat-specialize.c.inc b/fpu/softfloat-specialize.c.inc
index a0c740e544d..8e3124c11a6 100644
--- a/fpu/softfloat-specialize.c.inc
+++ b/fpu/softfloat-specialize.c.inc
@@ -404,15 +404,9 @@ static int pickNaN(FloatClass a_cls, FloatClass b_cls,
     || defined(TARGET_RISCV) || defined(TARGET_SH4) \
     || defined(TARGET_TRICORE) || defined(TARGET_ARM) || defined(TARGET_MIPS) \
     || defined(TARGET_LOONGARCH64) || defined(TARGET_HPPA) \
-    || defined(TARGET_S390X)
+    || defined(TARGET_S390X) || defined(TARGET_PPC)
         g_assert_not_reached();
-#elif defined(TARGET_PPC) || defined(TARGET_M68K)
-        /*
-         * PowerPC propagation rules:
-         *  1. A if it sNaN or qNaN
-         *  2. B if it sNaN or qNaN
-         * A signaling NaN is always silenced before returning it.
-         */
+#elif defined(TARGET_M68K)
         /*
          * M68000 FAMILY PROGRAMMER'S REFERENCE MANUAL
          * 3.4 FLOATING-POINT INSTRUCTION DETAILS
-- 
2.34.1

Re: [PATCH 08/21] target/ppc: Explicitly set 2-NaN propagation rule

Posted by Richard Henderson 3 weeks, 5 days ago

On 10/25/24 15:12, Peter Maydell wrote:
> Set the 2-NaN propagation rule explicitly in env->fp_status
> and env->vec_status.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


> ---
> As an aside, it looks a bit suspicious that we set
> tininess_before_rounding on fp_status but not vec_status...

Indeed.


r~