[Qemu-arm] [PATCH 2/2] target/arm: Gate "miscellaneous FP" insns by ID register field

[Peter Maydell]

There is a set of VFP instructions which we implement in
disas_vfp_v8_insn() and gate on the ARM_FEATURE_V8 bit.
These were all first introduced in v8 for A-profile, but in
M-profile they appeared in v7M. Gate them on the MVFR2
FPMisc field instead, and rename the function appropriately.

Signed-off-by: Peter Maydell <address@hidden>
---
 target/arm/cpu.h       | 20 ++++++++++++++++++++
 target/arm/translate.c | 21 +++++++++++++--------
 2 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 36ea3b58567..ff9ba387b42 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -3328,6 +3328,26 @@ static inline bool isar_feature_aa32_fp16_dpconv(const 
ARMISARegisters *id)
     return FIELD_EX64(id->mvfr1, MVFR1, FPHP) > 1;
 }
 
+static inline bool isar_feature_aa32_vsel(const ARMISARegisters *id)
+{
+    return FIELD_EX64(id->mvfr2, MVFR2, FPMISC) >= 1;
+}
+
+static inline bool isar_feature_aa32_vcvt_dr(const ARMISARegisters *id)
+{
+    return FIELD_EX64(id->mvfr2, MVFR2, FPMISC) >= 2;
+}
+
+static inline bool isar_feature_aa32_vrint(const ARMISARegisters *id)
+{
+    return FIELD_EX64(id->mvfr2, MVFR2, FPMISC) >= 3;
+}
+
+static inline bool isar_feature_aa32_vminmaxnm(const ARMISARegisters *id)
+{
+    return FIELD_EX64(id->mvfr2, MVFR2, FPMISC) >= 4;
+}
+
 /*
  * 64-bit feature tests via id registers.
  */
diff --git a/target/arm/translate.c b/target/arm/translate.c
index b7702fb49f7..af8f9e669b8 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -3357,7 +3357,7 @@ static const uint8_t fp_decode_rm[] = {
     FPROUNDING_NEGINF,
 };
 
-static int disas_vfp_v8_insn(DisasContext *s, uint32_t insn)
+static int disas_vfp_misc_insn(DisasContext *s, uint32_t insn)
 {
     uint32_t rd, rn, rm, dp = extract32(insn, 8, 1);
 
@@ -3375,15 +3375,18 @@ static int disas_vfp_v8_insn(DisasContext *s, uint32_t 
insn)
         rm = VFP_SREG_M(insn);
     }
 
-    if ((insn & 0x0f800e50) == 0x0e000a00) {
+    if ((insn & 0x0f800e50) == 0x0e000a00 && dc_isar_feature(aa32_vsel, s)) {
         return handle_vsel(insn, rd, rn, rm, dp);
-    } else if ((insn & 0x0fb00e10) == 0x0e800a00) {
+    } else if ((insn & 0x0fb00e10) == 0x0e800a00 &&
+               dc_isar_feature(aa32_vminmaxnm, s)) {
         return handle_vminmaxnm(insn, rd, rn, rm, dp);
-    } else if ((insn & 0x0fbc0ed0) == 0x0eb80a40) {
+    } else if ((insn & 0x0fbc0ed0) == 0x0eb80a40 &&
+               dc_isar_feature(aa32_vrint, s)) {
         /* VRINTA, VRINTN, VRINTP, VRINTM */
         int rounding = fp_decode_rm[extract32(insn, 16, 2)];
         return handle_vrint(insn, rd, rm, dp, rounding);
-    } else if ((insn & 0x0fbc0e50) == 0x0ebc0a40) {
+    } else if ((insn & 0x0fbc0e50) == 0x0ebc0a40 &&
+               dc_isar_feature(aa32_vcvt_dr, s)) {
         /* VCVTA, VCVTN, VCVTP, VCVTM */
         int rounding = fp_decode_rm[extract32(insn, 16, 2)];
         return handle_vcvt(insn, rd, rm, dp, rounding);
@@ -3427,10 +3430,12 @@ static int disas_vfp_insn(DisasContext *s, uint32_t 
insn)
     }
 
     if (extract32(insn, 28, 4) == 0xf) {
-        /* Encodings with T=1 (Thumb) or unconditional (ARM):
-         * only used in v8 and above.
+        /*
+         * Encodings with T=1 (Thumb) or unconditional (ARM):
+         * only used for the "miscellaneous VFP features" added in v8A
+         * and v7M (and gated on the MVFR2.FPMisc field).
          */
-        return disas_vfp_v8_insn(s, insn);
+        return disas_vfp_misc_insn(s, insn);
     }
 
     dp = ((insn & 0xf00) == 0xb00);
-- 
2.20.1