[Qemu-devel] [PULL 24/24] target/arm: Only implement doubles if the FPU supports them

[Peter Maydell]

The architecture permits FPUs which have only single-precision
support, not double-precision; Cortex-M4 and Cortex-M33 are
both like that. Add the necessary checks on the MVFR0 FPDP
field so that we UNDEF any double-precision instructions on
CPUs like this.

Note that even if FPDP==0 the insns like VMOV-to/from-gpreg,
VLDM/VSTM, VLDR/VSTR which take double precision registers
still exist.

Signed-off-by: Peter Maydell <address@hidden>
Reviewed-by: Richard Henderson <address@hidden>
Message-id: address@hidden
---
 target/arm/cpu.h               |  6 +++
 target/arm/translate-vfp.inc.c | 84 ++++++++++++++++++++++++++++++++++
 2 files changed, 90 insertions(+)

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index a98c45b1ff0..f9da672be57 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -3388,6 +3388,12 @@ static inline bool isar_feature_aa32_fpshvec(const 
ARMISARegisters *id)
     return FIELD_EX64(id->mvfr0, MVFR0, FPSHVEC) > 0;
 }
 
+static inline bool isar_feature_aa32_fpdp(const ARMISARegisters *id)
+{
+    /* Return true if CPU supports double precision floating point */
+    return FIELD_EX64(id->mvfr0, MVFR0, FPDP) > 0;
+}
+
 /*
  * We always set the FP and SIMD FP16 fields to indicate identical
  * levels of support (assuming SIMD is implemented at all), so
diff --git a/target/arm/translate-vfp.inc.c b/target/arm/translate-vfp.inc.c
index 390441a1104..348173d6026 100644
--- a/target/arm/translate-vfp.inc.c
+++ b/target/arm/translate-vfp.inc.c
@@ -206,6 +206,11 @@ static bool trans_VSEL(DisasContext *s, arg_VSEL *a)
         ((a->vm | a->vn | a->vd) & 0x10)) {
         return false;
     }
+
+    if (dp && !dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     rd = a->vd;
     rn = a->vn;
     rm = a->vm;
@@ -334,6 +339,11 @@ static bool trans_VMINMAXNM(DisasContext *s, arg_VMINMAXNM 
*a)
         ((a->vm | a->vn | a->vd) & 0x10)) {
         return false;
     }
+
+    if (dp && !dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     rd = a->vd;
     rn = a->vn;
     rm = a->vm;
@@ -415,6 +425,11 @@ static bool trans_VRINT(DisasContext *s, arg_VRINT *a)
         ((a->vm | a->vd) & 0x10)) {
         return false;
     }
+
+    if (dp && !dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     rd = a->vd;
     rm = a->vm;
 
@@ -473,6 +488,11 @@ static bool trans_VCVT(DisasContext *s, arg_VCVT *a)
     if (dp && !dc_isar_feature(aa32_fp_d32, s) && (a->vm & 0x10)) {
         return false;
     }
+
+    if (dp && !dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     rd = a->vd;
     rm = a->vm;
 
@@ -1301,6 +1321,10 @@ static bool do_vfp_3op_dp(DisasContext *s, VFPGen3OpDPFn 
*fn,
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!dc_isar_feature(aa32_fpshvec, s) &&
         (veclen != 0 || s->vec_stride != 0)) {
         return false;
@@ -1446,6 +1470,10 @@ static bool do_vfp_2op_dp(DisasContext *s, VFPGen2OpDPFn 
*fn, int vd, int vm)
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!dc_isar_feature(aa32_fpshvec, s) &&
         (veclen != 0 || s->vec_stride != 0)) {
         return false;
@@ -1743,6 +1771,10 @@ static bool trans_VFM_sp(DisasContext *s, arg_VFM_sp *a)
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -1901,6 +1933,10 @@ static bool trans_VMOV_imm_dp(DisasContext *s, 
arg_VMOV_imm_dp *a)
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!dc_isar_feature(aa32_fpshvec, s) &&
         (veclen != 0 || s->vec_stride != 0)) {
         return false;
@@ -2041,6 +2077,10 @@ static bool trans_VCMP_dp(DisasContext *s, arg_VCMP_dp 
*a)
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2110,6 +2150,10 @@ static bool trans_VCVT_f64_f16(DisasContext *s, 
arg_VCVT_f64_f16 *a)
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2172,6 +2216,10 @@ static bool trans_VCVT_f16_f64(DisasContext *s, 
arg_VCVT_f16_f64 *a)
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2228,6 +2276,10 @@ static bool trans_VRINTR_dp(DisasContext *s, 
arg_VRINTR_dp *a)
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2285,6 +2337,10 @@ static bool trans_VRINTZ_dp(DisasContext *s, 
arg_VRINTZ_dp *a)
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2340,6 +2396,10 @@ static bool trans_VRINTX_dp(DisasContext *s, 
arg_VRINTX_dp *a)
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2364,6 +2424,10 @@ static bool trans_VCVT_sp(DisasContext *s, arg_VCVT_sp 
*a)
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2388,6 +2452,10 @@ static bool trans_VCVT_dp(DisasContext *s, arg_VCVT_dp 
*a)
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2438,6 +2506,10 @@ static bool trans_VCVT_int_dp(DisasContext *s, 
arg_VCVT_int_dp *a)
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2474,6 +2546,10 @@ static bool trans_VJCVT(DisasContext *s, arg_VJCVT *a)
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2563,6 +2639,10 @@ static bool trans_VCVT_fix_dp(DisasContext *s, 
arg_VCVT_fix_dp *a)
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2655,6 +2735,10 @@ static bool trans_VCVT_dp_int(DisasContext *s, 
arg_VCVT_dp_int *a)
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
-- 
2.20.1