[Qemu-devel] [PATCH 2/2] ARM: wire up the softfloat flush_input_to_zero flag

[Peter Maydell]

Wire up the new softfloat support for flushing input denormals
to zero on ARM. The FPSCR FZ bit enables flush-to-zero for
both inputs and outputs, but the reporting of when inputs are
flushed to zero is via a separate IDC bit rather than the UFC
(underflow) bit used when output denormals are flushed to zero.

Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
---
 target-arm/helper.c |   10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/target-arm/helper.c b/target-arm/helper.c
index 50c1017..705b99f 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -2242,6 +2242,8 @@ static inline int vfp_exceptbits_from_host(int host_bits)
         target_bits |= 8;
     if (host_bits & float_flag_inexact)
         target_bits |= 0x10;
+    if (host_bits & float_flag_input_denormal)
+        target_bits |= 0x80;
     return target_bits;
 }
 
@@ -2278,6 +2280,8 @@ static inline int vfp_exceptbits_to_host(int target_bits)
         host_bits |= float_flag_underflow;
     if (target_bits & 0x10)
         host_bits |= float_flag_inexact;
+    if (target_bits & 0x80)
+        host_bits |= float_flag_input_denormal;
     return host_bits;
 }
 
@@ -2310,12 +2314,14 @@ void HELPER(vfp_set_fpscr)(CPUState *env, uint32_t val)
         }
         set_float_rounding_mode(i, &env->vfp.fp_status);
     }
-    if (changed & (1 << 24))
+    if (changed & (1 << 24)) {
         set_flush_to_zero((val & (1 << 24)) != 0, &env->vfp.fp_status);
+        set_flush_inputs_to_zero((val & (1 << 24)) != 0, &env->vfp.fp_status);
+    }
     if (changed & (1 << 25))
         set_default_nan_mode((val & (1 << 25)) != 0, &env->vfp.fp_status);
 
-    i = vfp_exceptbits_to_host((val >> 8) & 0x1f);
+    i = vfp_exceptbits_to_host(val);
     set_float_exception_flags(i, &env->vfp.fp_status);
 }
 
-- 
1.6.3.3