commit 1120827fa182f0e76226df7ffe7a86598d1df54f
author Peter Maydell <peter.maydell@linaro.org> Fri Jun 14 11:44:57 2019 +0100
committer Peter Maydell <peter.maydell@linaro.org> Mon Jun 17 15:15:06 2019 +0100
tree 35f39f957b3609984733a4daf3450af639eb2aba
parent 83655223ac6143a563e981906ce13fd6f2cfbefd

target/arm: Only implement doubles if the FPU supports them

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 <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190614104457.24703-3-peter.maydell@linaro.org

target/arm/cpu.h

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index a98c45b..f9da672 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -3388,6 +3388,12 @@
     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

target/arm/translate-vfp.inc.c

diff --git a/target/arm/translate-vfp.inc.c b/target/arm/translate-vfp.inc.c
index 390441a..348173d 100644
--- a/target/arm/translate-vfp.inc.c
+++ b/target/arm/translate-vfp.inc.c
@@ -206,6 +206,11 @@
         ((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 @@
         ((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 @@
         ((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 @@
     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 @@
         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 @@
         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 @@
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -1901,6 +1933,10 @@
         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 @@
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2110,6 +2150,10 @@
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2172,6 +2216,10 @@
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2228,6 +2276,10 @@
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2285,6 +2337,10 @@
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2340,6 +2396,10 @@
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2364,6 +2424,10 @@
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2388,6 +2452,10 @@
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2438,6 +2506,10 @@
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2474,6 +2546,10 @@
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2563,6 +2639,10 @@
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }
@@ -2655,6 +2735,10 @@
         return false;
     }
 
+    if (!dc_isar_feature(aa32_fpdp, s)) {
+        return false;
+    }
+
     if (!vfp_access_check(s)) {
         return true;
     }