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authorPeter Maydell <peter.maydell@linaro.org>2025-02-24 11:15:22 +0000
committerPeter Maydell <peter.maydell@linaro.org>2025-02-25 15:32:57 +0000
commit3abed4d0eace62910e90c206cb9d5741c6095b12 (patch)
tree27f7393f1f58c980ccb8c245b83f360a144d24bc
parent2e01cfea0735889a1e0481fc783d621779439572 (diff)
downloadfocaccia-qemu-3abed4d0eace62910e90c206cb9d5741c6095b12.tar.gz
focaccia-qemu-3abed4d0eace62910e90c206cb9d5741c6095b12.zip
fpu: Always decide snan_bit_is_one() at runtime
Currently we have a compile-time shortcut where we return a hardcode
value from snan_bit_is_one() on everything except MIPS, because we
know that's the only target that needs to change
status->no_signaling_nans at runtime.

Remove the ifdef, so we always look at the status flag.  This means
we must update the two targets (HPPA and SH4) that were previously
hardcoded to return true so that they set the status flag correctly.

This has no behavioural change, but will be necessary if we want to
build softfloat once for all targets.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250224111524.1101196-11-peter.maydell@linaro.org
Message-id: 20250217125055.160887-9-peter.maydell@linaro.org
-rw-r--r--fpu/softfloat-specialize.c.inc7
-rw-r--r--target/hppa/fpu_helper.c1
-rw-r--r--target/sh4/cpu.c1
3 files changed, 2 insertions, 7 deletions
diff --git a/fpu/softfloat-specialize.c.inc b/fpu/softfloat-specialize.c.inc
index a2c6afad5d..ba4fa08b7b 100644
--- a/fpu/softfloat-specialize.c.inc
+++ b/fpu/softfloat-specialize.c.inc
@@ -93,17 +93,10 @@ static inline bool no_signaling_nans(float_status *status)
  * In IEEE 754-1985 this was implementation defined, but in IEEE 754-2008
  * the msb must be zero.  MIPS is (so far) unique in supporting both the
  * 2008 revision and backward compatibility with their original choice.
- * Thus for MIPS we must make the choice at runtime.
  */
 static inline bool snan_bit_is_one(float_status *status)
 {
-#if defined(TARGET_MIPS)
     return status->snan_bit_is_one;
-#elif defined(TARGET_HPPA) || defined(TARGET_SH4)
-    return 1;
-#else
-    return 0;
-#endif
 }
 
 /*----------------------------------------------------------------------------
diff --git a/target/hppa/fpu_helper.c b/target/hppa/fpu_helper.c
index 8ff4b44804..a62d9d3083 100644
--- a/target/hppa/fpu_helper.c
+++ b/target/hppa/fpu_helper.c
@@ -67,6 +67,7 @@ void HELPER(loaded_fr0)(CPUHPPAState *env)
     set_float_infzeronan_rule(float_infzeronan_dnan_never, &env->fp_status);
     /* Default NaN: sign bit clear, msb-1 frac bit set */
     set_float_default_nan_pattern(0b00100000, &env->fp_status);
+    set_snan_bit_is_one(true, &env->fp_status);
     /*
      * "PA-RISC 2.0 Architecture" says it is IMPDEF whether the flushing
      * enabled by FPSR.D happens before or after rounding. We pick "before"
diff --git a/target/sh4/cpu.c b/target/sh4/cpu.c
index 4ac693d99b..ccfe222bdf 100644
--- a/target/sh4/cpu.c
+++ b/target/sh4/cpu.c
@@ -128,6 +128,7 @@ static void superh_cpu_reset_hold(Object *obj, ResetType type)
     set_flush_to_zero(1, &env->fp_status);
 #endif
     set_default_nan_mode(1, &env->fp_status);
+    set_snan_bit_is_one(true, &env->fp_status);
     /* sign bit clear, set all frac bits other than msb */
     set_float_default_nan_pattern(0b00111111, &env->fp_status);
     /*