target/arm: Implement FEAT_HBC

FEAT_HBC (Hinted conditional branches) provides a new instruction
BC.cond, which behaves exactly like the existing B.cond except
that it provides a hint to the branch predictor about the
likely behaviour of the branch.

Since QEMU does not implement branch prediction, we can treat
this identically to B.cond.

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>

1 files changed, 5 insertions, 0 deletions

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 7ba2402..bc7a69a 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -4088,6 +4088,11 @@ static inline bool isar_feature_aa64_i8mm(const ARMISARegisters *id)
     return FIELD_EX64(id->id_aa64isar1, ID_AA64ISAR1, I8MM) != 0;
 }
 
+static inline bool isar_feature_aa64_hbc(const ARMISARegisters *id)
+{
+    return FIELD_EX64(id->id_aa64isar2, ID_AA64ISAR2, BC) != 0;
+}
+
 static inline bool isar_feature_aa64_tgran4_lpa2(const ARMISARegisters *id)
 {
     return FIELD_SEX64(id->id_aa64mmfr0, ID_AA64MMFR0, TGRAN4) >= 1;