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

[PATCH 18/21] target/microblaze: Explicitly set 2-NaN propagation rule

Posted by Peter Maydell 4 weeks, 1 day ago

Set the NaN propagation rule explicitly for the float_status word
used in the microblaze target.

This is probably not the architecturally correct behaviour,
but since this is a no-behaviour-change patch, we leave a
TODO note to that effect.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/microblaze/cpu.c        | 5 +++++
 fpu/softfloat-specialize.c.inc | 3 ++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/target/microblaze/cpu.c b/target/microblaze/cpu.c
index 6329a774331..14286deead9 100644
--- a/target/microblaze/cpu.c
+++ b/target/microblaze/cpu.c
@@ -202,6 +202,11 @@ static void mb_cpu_reset_hold(Object *obj, ResetType type)
     env->pc = cpu->cfg.base_vectors;
 
     set_float_rounding_mode(float_round_nearest_even, &env->fp_status);
+    /*
+     * TODO: this is probably not the correct NaN propagation rule for
+     * this architecture.
+     */
+    set_float_2nan_prop_rule(float_2nan_prop_x87, &env->fp_status);
 
 #if defined(CONFIG_USER_ONLY)
     /* start in user mode with interrupts enabled.  */
diff --git a/fpu/softfloat-specialize.c.inc b/fpu/softfloat-specialize.c.inc
index a5c3e2b8de5..40cbb1ab73b 100644
--- a/fpu/softfloat-specialize.c.inc
+++ b/fpu/softfloat-specialize.c.inc
@@ -406,7 +406,8 @@ static int pickNaN(FloatClass a_cls, FloatClass b_cls,
     || defined(TARGET_LOONGARCH64) || defined(TARGET_HPPA) \
     || defined(TARGET_S390X) || defined(TARGET_PPC) || defined(TARGET_M68K) \
     || defined(TARGET_SPARC) || defined(TARGET_XTENSA) \
-    || defined(TARGET_I386) || defined(TARGET_ALPHA)
+    || defined(TARGET_I386) || defined(TARGET_ALPHA) \
+    || defined(TARGET_MICROBLAZE)
         g_assert_not_reached();
 #else
         rule = float_2nan_prop_x87;
-- 
2.34.1

Re: [PATCH 18/21] target/microblaze: 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 NaN propagation rule explicitly for the float_status word
> used in the microblaze target.
> 
> This is probably not the architecturally correct behaviour,
> but since this is a no-behaviour-change patch, we leave a
> TODO note to that effect.
> 
> Signed-off-by: Peter Maydell<peter.maydell@linaro.org>
> ---
>   target/microblaze/cpu.c        | 5 +++++
>   fpu/softfloat-specialize.c.inc | 3 ++-
>   2 files changed, 7 insertions(+), 1 deletion(-)

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

r~

Re: [PATCH 18/21] target/microblaze: Explicitly set 2-NaN propagation rule

Posted by Philippe Mathieu-Daudé 4 weeks ago

On 25/10/24 11:12, Peter Maydell wrote:
> Set the NaN propagation rule explicitly for the float_status word
> used in the microblaze target.
> 
> This is probably not the architecturally correct behaviour,
> but since this is a no-behaviour-change patch, we leave a
> TODO note to that effect.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>   target/microblaze/cpu.c        | 5 +++++
>   fpu/softfloat-specialize.c.inc | 3 ++-
>   2 files changed, 7 insertions(+), 1 deletion(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>