fpu/softfloat: implement float16_squash_input_denormal

This will be required when expanding the MINMAX() macro for 16
bit/half-precision operations.

Backports commit 210cbd4910ae9e41e0a1785b96890ea2c291b381 from qemu

qemu/aarch64.h

@@ -491,6 +491,7 @@
 #define float16_is_quiet_nan float16_is_quiet_nan_aarch64
 #define float16_is_signaling_nan float16_is_signaling_nan_aarch64
 #define float16_maybe_silence_nan float16_maybe_silence_nan_aarch64
+#define float16_squash_input_denormal float16_squash_input_denormal_aarch64
 #define float16_to_float32 float16_to_float32_aarch64
 #define float16_to_float64 float16_to_float64_aarch64
 #define float32ToCommonNaN float32ToCommonNaN_aarch64

qemu/aarch64eb.h

@@ -491,6 +491,7 @@
 #define float16_is_quiet_nan float16_is_quiet_nan_aarch64eb
 #define float16_is_signaling_nan float16_is_signaling_nan_aarch64eb
 #define float16_maybe_silence_nan float16_maybe_silence_nan_aarch64eb
+#define float16_squash_input_denormal float16_squash_input_denormal_aarch64eb
 #define float16_to_float32 float16_to_float32_aarch64eb
 #define float16_to_float64 float16_to_float64_aarch64eb
 #define float32ToCommonNaN float32ToCommonNaN_aarch64eb

qemu/arm.h

@@ -491,6 +491,7 @@
 #define float16_is_quiet_nan float16_is_quiet_nan_arm
 #define float16_is_signaling_nan float16_is_signaling_nan_arm
 #define float16_maybe_silence_nan float16_maybe_silence_nan_arm
+#define float16_squash_input_denormal float16_squash_input_denormal_arm
 #define float16_to_float32 float16_to_float32_arm
 #define float16_to_float64 float16_to_float64_arm
 #define float32ToCommonNaN float32ToCommonNaN_arm

qemu/armeb.h

@@ -491,6 +491,7 @@
 #define float16_is_quiet_nan float16_is_quiet_nan_armeb
 #define float16_is_signaling_nan float16_is_signaling_nan_armeb
 #define float16_maybe_silence_nan float16_maybe_silence_nan_armeb
+#define float16_squash_input_denormal float16_squash_input_denormal_armeb
 #define float16_to_float32 float16_to_float32_armeb
 #define float16_to_float64 float16_to_float64_armeb
 #define float32ToCommonNaN float32ToCommonNaN_armeb

qemu/fpu/softfloat.c

@@ -3452,6 +3452,21 @@ static float16 roundAndPackFloat16(flag zSign, int zExp,
     return packFloat16(zSign, zExp, zSig >> 13);
 }
 
+/*----------------------------------------------------------------------------
+| If `a' is denormal and we are in flush-to-zero mode then set the
+| input-denormal exception and return zero. Otherwise just return the value.
+*----------------------------------------------------------------------------*/
+float16 float16_squash_input_denormal(float16 a, float_status *status)
+{
+    if (status->flush_inputs_to_zero) {
+        if (extractFloat16Exp(a) == 0 && extractFloat16Frac(a) != 0) {
+            float_raise(float_flag_input_denormal, status);
+            return make_float16(float16_val(a) & 0x8000);
+        }
+    }
+    return a;
+}
+
 static void normalizeFloat16Subnormal(uint32_t aSig, int *zExpPtr,
                                       uint32_t *zSigPtr)
 {

qemu/header_gen.py

@@ -497,6 +497,7 @@ symbols = (
     'float16_is_quiet_nan',
     'float16_is_signaling_nan',
     'float16_maybe_silence_nan',
+    'float16_squash_input_denormal',
     'float16_to_float32',
     'float16_to_float64',
     'float32ToCommonNaN',

qemu/include/fpu/softfloat.h

@@ -289,6 +289,7 @@ void float_raise(uint8_t flags, float_status *status);
 | If `a' is denormal and we are in flush-to-zero mode then set the
 | input-denormal exception and return zero. Otherwise just return the value.
 *----------------------------------------------------------------------------*/
+float16 float16_squash_input_denormal(float16 a, float_status *status);
 float32 float32_squash_input_denormal(float32 a, float_status *status);
 float64 float64_squash_input_denormal(float64 a, float_status *status);
 

qemu/m68k.h

@@ -491,6 +491,7 @@
 #define float16_is_quiet_nan float16_is_quiet_nan_m68k
 #define float16_is_signaling_nan float16_is_signaling_nan_m68k
 #define float16_maybe_silence_nan float16_maybe_silence_nan_m68k
+#define float16_squash_input_denormal float16_squash_input_denormal_m68k
 #define float16_to_float32 float16_to_float32_m68k
 #define float16_to_float64 float16_to_float64_m68k
 #define float32ToCommonNaN float32ToCommonNaN_m68k

qemu/mips.h

@@ -491,6 +491,7 @@
 #define float16_is_quiet_nan float16_is_quiet_nan_mips
 #define float16_is_signaling_nan float16_is_signaling_nan_mips
 #define float16_maybe_silence_nan float16_maybe_silence_nan_mips
+#define float16_squash_input_denormal float16_squash_input_denormal_mips
 #define float16_to_float32 float16_to_float32_mips
 #define float16_to_float64 float16_to_float64_mips
 #define float32ToCommonNaN float32ToCommonNaN_mips

qemu/mips64.h

@@ -491,6 +491,7 @@
 #define float16_is_quiet_nan float16_is_quiet_nan_mips64
 #define float16_is_signaling_nan float16_is_signaling_nan_mips64
 #define float16_maybe_silence_nan float16_maybe_silence_nan_mips64
+#define float16_squash_input_denormal float16_squash_input_denormal_mips64
 #define float16_to_float32 float16_to_float32_mips64
 #define float16_to_float64 float16_to_float64_mips64
 #define float32ToCommonNaN float32ToCommonNaN_mips64

qemu/mips64el.h

@@ -491,6 +491,7 @@
 #define float16_is_quiet_nan float16_is_quiet_nan_mips64el
 #define float16_is_signaling_nan float16_is_signaling_nan_mips64el
 #define float16_maybe_silence_nan float16_maybe_silence_nan_mips64el
+#define float16_squash_input_denormal float16_squash_input_denormal_mips64el
 #define float16_to_float32 float16_to_float32_mips64el
 #define float16_to_float64 float16_to_float64_mips64el
 #define float32ToCommonNaN float32ToCommonNaN_mips64el

qemu/mipsel.h

@@ -491,6 +491,7 @@
 #define float16_is_quiet_nan float16_is_quiet_nan_mipsel
 #define float16_is_signaling_nan float16_is_signaling_nan_mipsel
 #define float16_maybe_silence_nan float16_maybe_silence_nan_mipsel
+#define float16_squash_input_denormal float16_squash_input_denormal_mipsel
 #define float16_to_float32 float16_to_float32_mipsel
 #define float16_to_float64 float16_to_float64_mipsel
 #define float32ToCommonNaN float32ToCommonNaN_mipsel

qemu/powerpc.h

@@ -491,6 +491,7 @@
 #define float16_is_quiet_nan float16_is_quiet_nan_powerpc
 #define float16_is_signaling_nan float16_is_signaling_nan_powerpc
 #define float16_maybe_silence_nan float16_maybe_silence_nan_powerpc
+#define float16_squash_input_denormal float16_squash_input_denormal_powerpc
 #define float16_to_float32 float16_to_float32_powerpc
 #define float16_to_float64 float16_to_float64_powerpc
 #define float32ToCommonNaN float32ToCommonNaN_powerpc

qemu/sparc.h

@@ -491,6 +491,7 @@
 #define float16_is_quiet_nan float16_is_quiet_nan_sparc
 #define float16_is_signaling_nan float16_is_signaling_nan_sparc
 #define float16_maybe_silence_nan float16_maybe_silence_nan_sparc
+#define float16_squash_input_denormal float16_squash_input_denormal_sparc
 #define float16_to_float32 float16_to_float32_sparc
 #define float16_to_float64 float16_to_float64_sparc
 #define float32ToCommonNaN float32ToCommonNaN_sparc

qemu/sparc64.h

@@ -491,6 +491,7 @@
 #define float16_is_quiet_nan float16_is_quiet_nan_sparc64
 #define float16_is_signaling_nan float16_is_signaling_nan_sparc64
 #define float16_maybe_silence_nan float16_maybe_silence_nan_sparc64
+#define float16_squash_input_denormal float16_squash_input_denormal_sparc64
 #define float16_to_float32 float16_to_float32_sparc64
 #define float16_to_float64 float16_to_float64_sparc64
 #define float32ToCommonNaN float32ToCommonNaN_sparc64

qemu/x86_64.h

@@ -491,6 +491,7 @@
 #define float16_is_quiet_nan float16_is_quiet_nan_x86_64
 #define float16_is_signaling_nan float16_is_signaling_nan_x86_64
 #define float16_maybe_silence_nan float16_maybe_silence_nan_x86_64
+#define float16_squash_input_denormal float16_squash_input_denormal_x86_64
 #define float16_to_float32 float16_to_float32_x86_64
 #define float16_to_float64 float16_to_float64_x86_64
 #define float32ToCommonNaN float32ToCommonNaN_x86_64