target/arm: Use MVFR1 feature bits to gate A32/T32 FP16 instructions

Instead of gating the A32/T32 FP16 conversion instructions on
the ARM_FEATURE_VFP_FP16 flag, switch to our new approach of
looking at ID register bits. In this case MVFR1 fields FPHP
and SIMDHP indicate the presence of these insns.

This change doesn't alter behaviour for any of our CPUs.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190222170936.13268-2-peter.maydell@linaro.org

diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 4d7f6a3bc0ca2d68c24b1fcf230ccf25f8a5a5d3..a3baf4eeed1ea2d89f579a6c5af725785641dcf6 100644 (file)
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -1014,7 +1014,6 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
     }
     if (arm_feature(env, ARM_FEATURE_VFP4)) {
         set_feature(env, ARM_FEATURE_VFP3);
-        set_feature(env, ARM_FEATURE_VFP_FP16);
     }
     if (arm_feature(env, ARM_FEATURE_VFP3)) {
         set_feature(env, ARM_FEATURE_VFP);
@@ -1675,7 +1674,6 @@ static void cortex_a9_initfn(Object *obj)
     cpu->dtb_compatible = "arm,cortex-a9";
     set_feature(&cpu->env, ARM_FEATURE_V7);
     set_feature(&cpu->env, ARM_FEATURE_VFP3);
-    set_feature(&cpu->env, ARM_FEATURE_VFP_FP16);
     set_feature(&cpu->env, ARM_FEATURE_NEON);
     set_feature(&cpu->env, ARM_FEATURE_THUMB2EE);
     set_feature(&cpu->env, ARM_FEATURE_EL3);

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 1eea1a408b87a8e1af5a9c52590b8c6cbf2b26f5..36ea3b585676403b342969d1121be0f23615852a 100644 (file)
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -1730,6 +1730,27 @@ FIELD(ID_DFR0, MPROFDBG, 20, 4)
 FIELD(ID_DFR0, PERFMON, 24, 4)
 FIELD(ID_DFR0, TRACEFILT, 28, 4)
 
+FIELD(MVFR0, SIMDREG, 0, 4)
+FIELD(MVFR0, FPSP, 4, 4)
+FIELD(MVFR0, FPDP, 8, 4)
+FIELD(MVFR0, FPTRAP, 12, 4)
+FIELD(MVFR0, FPDIVIDE, 16, 4)
+FIELD(MVFR0, FPSQRT, 20, 4)
+FIELD(MVFR0, FPSHVEC, 24, 4)
+FIELD(MVFR0, FPROUND, 28, 4)
+
+FIELD(MVFR1, FPFTZ, 0, 4)
+FIELD(MVFR1, FPDNAN, 4, 4)
+FIELD(MVFR1, SIMDLS, 8, 4)
+FIELD(MVFR1, SIMDINT, 12, 4)
+FIELD(MVFR1, SIMDSP, 16, 4)
+FIELD(MVFR1, SIMDHP, 20, 4)
+FIELD(MVFR1, FPHP, 24, 4)
+FIELD(MVFR1, SIMDFMAC, 28, 4)
+
+FIELD(MVFR2, SIMDMISC, 0, 4)
+FIELD(MVFR2, FPMISC, 4, 4)
+
 QEMU_BUILD_BUG_ON(ARRAY_SIZE(((ARMCPU *)0)->ccsidr) <= R_V7M_CSSELR_INDEX_MASK);
 
 /* If adding a feature bit which corresponds to a Linux ELF
@@ -1747,7 +1768,6 @@ enum arm_features {
     ARM_FEATURE_THUMB2,
     ARM_FEATURE_PMSA,   /* no MMU; may have Memory Protection Unit */
     ARM_FEATURE_VFP3,
-    ARM_FEATURE_VFP_FP16,
     ARM_FEATURE_NEON,
     ARM_FEATURE_M, /* Microcontroller profile.  */
     ARM_FEATURE_OMAPCP, /* OMAP specific CP15 ops handling.  */
@@ -3293,6 +3313,21 @@ static inline bool isar_feature_aa32_fp16_arith(const ARMISARegisters *id)
     return FIELD_EX64(id->id_aa64pfr0, ID_AA64PFR0, FP) == 1;
 }
 
+/*
+ * We always set the FP and SIMD FP16 fields to indicate identical
+ * levels of support (assuming SIMD is implemented at all), so
+ * we only need one set of accessors.
+ */
+static inline bool isar_feature_aa32_fp16_spconv(const ARMISARegisters *id)
+{
+    return FIELD_EX64(id->mvfr1, MVFR1, FPHP) > 0;
+}
+
+static inline bool isar_feature_aa32_fp16_dpconv(const ARMISARegisters *id)
+{
+    return FIELD_EX64(id->mvfr1, MVFR1, FPHP) > 1;
+}
+
 /*
  * 64-bit feature tests via id registers.
  */

diff --git a/target/arm/kvm32.c b/target/arm/kvm32.c
index a75e04cc8f3491290d6983f469b0336bcff99cd5..327375f6252f47cdbb439871855c853505ed3f01 100644 (file)
--- a/target/arm/kvm32.c
+++ b/target/arm/kvm32.c
@@ -125,9 +125,6 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
     if (extract32(id_pfr0, 12, 4) == 1) {
         set_feature(&features, ARM_FEATURE_THUMB2EE);
     }
-    if (extract32(ahcf->isar.mvfr1, 20, 4) == 1) {
-        set_feature(&features, ARM_FEATURE_VFP_FP16);
-    }
     if (extract32(ahcf->isar.mvfr1, 12, 4) == 1) {
         set_feature(&features, ARM_FEATURE_NEON);
     }

diff --git a/target/arm/translate.c b/target/arm/translate.c
index c1175798ac99c0a46465e2f6fa83c8114c287502..b7702fb49f7d6be2ad0793cd6b2b41f53d3d7a68 100644 (file)
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -3663,17 +3663,27 @@ static int disas_vfp_insn(DisasContext *s, uint32_t insn)
                      * UNPREDICTABLE if bit 8 is set prior to ARMv8
                      * (we choose to UNDEF)
                      */
-                    if ((dp && !arm_dc_feature(s, ARM_FEATURE_V8)) ||
-                        !arm_dc_feature(s, ARM_FEATURE_VFP_FP16)) {
-                        return 1;
+                    if (dp) {
+                        if (!dc_isar_feature(aa32_fp16_dpconv, s)) {
+                            return 1;
+                        }
+                    } else {
+                        if (!dc_isar_feature(aa32_fp16_spconv, s)) {
+                            return 1;
+                        }
                     }
                     rm_is_dp = false;
                     break;
                 case 0x06: /* vcvtb.f16.f32, vcvtb.f16.f64 */
                 case 0x07: /* vcvtt.f16.f32, vcvtt.f16.f64 */
-                    if ((dp && !arm_dc_feature(s, ARM_FEATURE_V8)) ||
-                        !arm_dc_feature(s, ARM_FEATURE_VFP_FP16)) {
-                        return 1;
+                    if (dp) {
+                        if (!dc_isar_feature(aa32_fp16_dpconv, s)) {
+                            return 1;
+                        }
+                    } else {
+                        if (!dc_isar_feature(aa32_fp16_spconv, s)) {
+                            return 1;
+                        }
                     }
                     rd_is_dp = false;
                     break;
@@ -7876,7 +7886,7 @@ static int disas_neon_data_insn(DisasContext *s, uint32_t insn)
                     TCGv_ptr fpst;
                     TCGv_i32 ahp;
 
-                    if (!arm_dc_feature(s, ARM_FEATURE_VFP_FP16) ||
+                    if (!dc_isar_feature(aa32_fp16_spconv, s) ||
                         q || (rm & 1)) {
                         return 1;
                     }
@@ -7908,7 +7918,7 @@ static int disas_neon_data_insn(DisasContext *s, uint32_t insn)
                 {
                     TCGv_ptr fpst;
                     TCGv_i32 ahp;
-                    if (!arm_dc_feature(s, ARM_FEATURE_VFP_FP16) ||
+                    if (!dc_isar_feature(aa32_fp16_spconv, s) ||
                         q || (rd & 1)) {
                         return 1;
                     }