target/arm: Implement MVE VCVT between single and half precision

Implement the MVE VCVT instruction which converts between single
and half precision floating point.

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

4 files changed, 108 insertions, 0 deletions

diff --git a/target/arm/helper-mve.h b/target/arm/helper-mve.h
index 6d4052a..f6345c7 100644
--- a/target/arm/helper-mve.h
+++ b/target/arm/helper-mve.h
@@ -182,6 +182,11 @@ DEF_HELPER_FLAGS_4(mve_vcvt_rm_uh, TCG_CALL_NO_WG, void, env, ptr, ptr, i32)
 DEF_HELPER_FLAGS_4(mve_vcvt_rm_ss, TCG_CALL_NO_WG, void, env, ptr, ptr, i32)
 DEF_HELPER_FLAGS_4(mve_vcvt_rm_us, TCG_CALL_NO_WG, void, env, ptr, ptr, i32)
 
+DEF_HELPER_FLAGS_3(mve_vcvtb_sh, TCG_CALL_NO_WG, void, env, ptr, ptr)
+DEF_HELPER_FLAGS_3(mve_vcvtt_sh, TCG_CALL_NO_WG, void, env, ptr, ptr)
+DEF_HELPER_FLAGS_3(mve_vcvtb_hs, TCG_CALL_NO_WG, void, env, ptr, ptr)
+DEF_HELPER_FLAGS_3(mve_vcvtt_hs, TCG_CALL_NO_WG, void, env, ptr, ptr)
+
 DEF_HELPER_FLAGS_3(mve_vmovnbb, TCG_CALL_NO_WG, void, env, ptr, ptr)
 DEF_HELPER_FLAGS_3(mve_vmovnbh, TCG_CALL_NO_WG, void, env, ptr, ptr)
 DEF_HELPER_FLAGS_3(mve_vmovntb, TCG_CALL_NO_WG, void, env, ptr, ptr)
diff --git a/target/arm/mve.decode b/target/arm/mve.decode
index 55e8ce3..10f0f1d 100644
--- a/target/arm/mve.decode
+++ b/target/arm/mve.decode
@@ -221,6 +221,8 @@ VMUL             1110 1111 0 . .. ... 0 ... 0 1001 . 1 . 1 ... 0 @2op
 # The VSHLL T2 encoding is not a @2op pattern, but is here because it
 # overlaps what would be size=0b11 VMULH/VRMULH
 {
+  VCVTB_SH       111 0 1110 0 . 11 1111 ... 0 1110 0 0 . 0 ... 1 @1op_nosz
+
   VMAXNMA        111 0 1110 0 . 11 1111 ... 0 1110 1 0 . 0 ... 1 @vmaxnma size=2
 
   VSHLL_BS       111 0 1110 0 . 11 .. 01 ... 0 1110 0 0 . 0 ... 1 @2_shll_esize_b
@@ -235,6 +237,8 @@ VMUL             1110 1111 0 . .. ... 0 ... 0 1001 . 1 . 1 ... 0 @2op
 }
 
 {
+  VCVTB_HS       111 1 1110 0 . 11  1111 ... 0 1110 0 0 . 0 ... 1  @1op_nosz
+
   VMAXNMA        111 1 1110 0 . 11  1111 ... 0 1110 1 0 . 0 ... 1 @vmaxnma size=1
 
   VSHLL_BU       111 1 1110 0 . 11 .. 01 ... 0 1110 0 0 . 0 ... 1 @2_shll_esize_b
@@ -247,6 +251,8 @@ VMUL             1110 1111 0 . .. ... 0 ... 0 1001 . 1 . 1 ... 0 @2op
 }
 
 {
+  VCVTT_SH       111 0 1110 0 . 11  1111 ... 1 1110 0 0 . 0 ... 1 @1op_nosz
+
   VMINNMA        111 0 1110 0 . 11  1111 ... 1 1110 1 0 . 0 ... 1 @vmaxnma size=2
   VSHLL_TS       111 0 1110 0 . 11 .. 01 ... 1 1110 0 0 . 0 ... 1 @2_shll_esize_b
   VSHLL_TS       111 0 1110 0 . 11 .. 01 ... 1 1110 0 0 . 0 ... 1 @2_shll_esize_h
@@ -260,6 +266,8 @@ VMUL             1110 1111 0 . .. ... 0 ... 0 1001 . 1 . 1 ... 0 @2op
 }
 
 {
+  VCVTT_HS       111 1 1110 0 . 11  1111 ... 1 1110 0 0 . 0 ... 1 @1op_nosz
+
   VMINNMA        111 1 1110 0 . 11  1111 ... 1 1110 1 0 . 0 ... 1 @vmaxnma size=1
   VSHLL_TU       111 1 1110 0 . 11 .. 01 ... 1 1110 0 0 . 0 ... 1 @2_shll_esize_b
   VSHLL_TU       111 1 1110 0 . 11 .. 01 ... 1 1110 0 0 . 0 ... 1 @2_shll_esize_h
diff --git a/target/arm/mve_helper.c b/target/arm/mve_helper.c
index a793199..1ed76ac 100644
--- a/target/arm/mve_helper.c
+++ b/target/arm/mve_helper.c
@@ -3332,3 +3332,84 @@ DO_VCVT_RMODE(vcvt_rm_sh, 2, uint16_t, helper_vfp_toshh)
 DO_VCVT_RMODE(vcvt_rm_uh, 2, uint16_t, helper_vfp_touhh)
 DO_VCVT_RMODE(vcvt_rm_ss, 4, uint32_t, helper_vfp_tosls)
 DO_VCVT_RMODE(vcvt_rm_us, 4, uint32_t, helper_vfp_touls)
+
+/*
+ * VCVT between halfprec and singleprec. As usual for halfprec
+ * conversions, FZ16 is ignored and AHP is observed.
+ */
+static void do_vcvt_sh(CPUARMState *env, void *vd, void *vm, int top)
+{
+    uint16_t *d = vd;
+    uint32_t *m = vm;
+    uint16_t r;
+    uint16_t mask = mve_element_mask(env);
+    bool ieee = !(env->vfp.xregs[ARM_VFP_FPSCR] & FPCR_AHP);
+    unsigned e;
+    float_status *fpst;
+    float_status scratch_fpst;
+    float_status *base_fpst = &env->vfp.standard_fp_status;
+    bool old_fz = get_flush_to_zero(base_fpst);
+    set_flush_to_zero(false, base_fpst);
+    for (e = 0; e < 16 / 4; e++, mask >>= 4) {
+        if ((mask & MAKE_64BIT_MASK(0, 4)) == 0) {
+            continue;
+        }
+        fpst = base_fpst;
+        if (!(mask & 1)) {
+            /* We need the result but without updating flags */
+            scratch_fpst = *fpst;
+            fpst = &scratch_fpst;
+        }
+        r = float32_to_float16(m[H4(e)], ieee, fpst);
+        mergemask(&d[H2(e * 2 + top)], r, mask >> (top * 2));
+    }
+    set_flush_to_zero(old_fz, base_fpst);
+    mve_advance_vpt(env);
+}
+
+static void do_vcvt_hs(CPUARMState *env, void *vd, void *vm, int top)
+{
+    uint32_t *d = vd;
+    uint16_t *m = vm;
+    uint32_t r;
+    uint16_t mask = mve_element_mask(env);
+    bool ieee = !(env->vfp.xregs[ARM_VFP_FPSCR] & FPCR_AHP);
+    unsigned e;
+    float_status *fpst;
+    float_status scratch_fpst;
+    float_status *base_fpst = &env->vfp.standard_fp_status;
+    bool old_fiz = get_flush_inputs_to_zero(base_fpst);
+    set_flush_inputs_to_zero(false, base_fpst);
+    for (e = 0; e < 16 / 4; e++, mask >>= 4) {
+        if ((mask & MAKE_64BIT_MASK(0, 4)) == 0) {
+            continue;
+        }
+        fpst = base_fpst;
+        if (!(mask & (1 << (top * 2)))) {
+            /* We need the result but without updating flags */
+            scratch_fpst = *fpst;
+            fpst = &scratch_fpst;
+        }
+        r = float16_to_float32(m[H2(e * 2 + top)], ieee, fpst);
+        mergemask(&d[H4(e)], r, mask);
+    }
+    set_flush_inputs_to_zero(old_fiz, base_fpst);
+    mve_advance_vpt(env);
+}
+
+void HELPER(mve_vcvtb_sh)(CPUARMState *env, void *vd, void *vm)
+{
+    do_vcvt_sh(env, vd, vm, 0);
+}
+void HELPER(mve_vcvtt_sh)(CPUARMState *env, void *vd, void *vm)
+{
+    do_vcvt_sh(env, vd, vm, 1);
+}
+void HELPER(mve_vcvtb_hs)(CPUARMState *env, void *vd, void *vm)
+{
+    do_vcvt_hs(env, vd, vm, 0);
+}
+void HELPER(mve_vcvtt_hs)(CPUARMState *env, void *vd, void *vm)
+{
+    do_vcvt_hs(env, vd, vm, 1);
+}
diff --git a/target/arm/translate-mve.c b/target/arm/translate-mve.c
index e80a55e..194ef99 100644
--- a/target/arm/translate-mve.c
+++ b/target/arm/translate-mve.c
@@ -627,6 +627,20 @@ DO_VCVT_RMODE(VCVTPU, FPROUNDING_POSINF, true)
 DO_VCVT_RMODE(VCVTMS, FPROUNDING_NEGINF, false)
 DO_VCVT_RMODE(VCVTMU, FPROUNDING_NEGINF, true)
 
+#define DO_VCVT_SH(INSN, FN)                                    \
+    static bool trans_##INSN(DisasContext *s, arg_1op *a)       \
+    {                                                           \
+        if (!dc_isar_feature(aa32_mve_fp, s)) {                 \
+            return false;                                       \
+        }                                                       \
+        return do_1op(s, a, gen_helper_mve_##FN);               \
+    }                                                           \
+
+DO_VCVT_SH(VCVTB_SH, vcvtb_sh)
+DO_VCVT_SH(VCVTT_SH, vcvtt_sh)
+DO_VCVT_SH(VCVTB_HS, vcvtb_hs)
+DO_VCVT_SH(VCVTT_HS, vcvtt_hs)
+
 /* Narrowing moves: only size 0 and 1 are valid */
 #define DO_VMOVN(INSN, FN) \
     static bool trans_##INSN(DisasContext *s, arg_1op *a)       \