target-arm: Give the FPSCR rounding modes names

When setting rounding modes we currently just hardcode the numeric values
for rounding modes in a big switch statement.

With AArch64 support coming, we will need to refer to these rounding modes
at different places throughout the code though, so let's better give them
names so we don't get confused by accident.
Signed-off-by: NAlexander Graf <agraf@suse.de>
[WN: Commit message tweak, use names from ARM ARM.]
Signed-off-by: NWill Newton <will.newton@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <rth@twiddle.net>

target-arm/cpu.h

@@ -487,6 +487,15 @@ static inline void vfp_set_fpcr(CPUARMState *env, uint32_t val)
     vfp_set_fpscr(env, new_fpscr);
 }
 
+enum arm_fprounding {
+    FPROUNDING_TIEEVEN,
+    FPROUNDING_POSINF,
+    FPROUNDING_NEGINF,
+    FPROUNDING_ZERO,
+    FPROUNDING_TIEAWAY,
+    FPROUNDING_ODD
+};
+
 enum arm_cpu_mode {
   ARM_CPU_MODE_USR = 0x10,
   ARM_CPU_MODE_FIQ = 0x11,

target-arm/helper.c

@@ -3815,16 +3815,16 @@ void HELPER(vfp_set_fpscr)(CPUARMState *env, uint32_t val)
     if (changed & (3 << 22)) {
         i = (val >> 22) & 3;
         switch (i) {
-        case 0:
+        case FPROUNDING_TIEEVEN:
             i = float_round_nearest_even;
             break;
-        case 1:
+        case FPROUNDING_POSINF:
             i = float_round_up;
             break;
-        case 2:
+        case FPROUNDING_NEGINF:
             i = float_round_down;
             break;
-        case 3:
+        case FPROUNDING_ZERO:
             i = float_round_to_zero;
             break;
         }