target/arm: Plumb FEAT_RPRES frecpe and frsqrte through to new helper

FEAT_RPRES implements an "increased precision" variant of the single
precision FRECPE and FRSQRTE instructions from an 8 bit to a 12
bit mantissa. This applies only when FPCR.AH == 1. Note that the
halfprec and double versions of these insns retain the 8 bit
precision regardless.

In this commit we add all the plumbing to make these instructions
call a new helper function when the increased-precision is in
effect. In the following commit we will provide the actual change
in behaviour in the helpers.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/target/arm/cpu-features.h b/target/arm/cpu-features.h
index 7bf24c506b..525e4cee12 100644
--- a/target/arm/cpu-features.h
+++ b/target/arm/cpu-features.h
@@ -597,6 +597,11 @@ static inline bool isar_feature_aa64_mops(const ARMISARegisters *id)
     return FIELD_EX64(id->id_aa64isar2, ID_AA64ISAR2, MOPS);
 }
 
+static inline bool isar_feature_aa64_rpres(const ARMISARegisters *id)
+{
+    return FIELD_EX64(id->id_aa64isar2, ID_AA64ISAR2, RPRES);
+}
+
 static inline bool isar_feature_aa64_fp_simd(const ARMISARegisters *id)
 {
     /* We always set the AdvSIMD and FP fields identically.  */