[PATCH v7 75/92] target/arm: Implement SVE2 FLOGB

[Richard Henderson <richard.henderson@linaro.org>]

From: Stephen Long <steplong@quicinc.com>

Signed-off-by: Stephen Long <steplong@quicinc.com>
Message-Id: <20200430191405.21641-1-steplong@quicinc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
v2: Fixed esz index and c++ comments
v3: Fixed denormal arithmetic and raise invalid.
v7: Rewrite; handle denormal exceptions and flush to zero.
---
 target/arm/helper-sve.h    |  4 ++
 target/arm/sve.decode      |  3 ++
 target/arm/sve_helper.c    | 88 ++++++++++++++++++++++++++++++++++++++
 target/arm/translate-sve.c | 24 +++++++++++
 4 files changed, 119 insertions(+)

diff --git a/target/arm/helper-sve.h b/target/arm/helper-sve.h
index be4b17f1c2..342bb83721 100644
--- a/target/arm/helper-sve.h
+++ b/target/arm/helper-sve.h
@@ -2754,3 +2754,7 @@ DEF_HELPER_FLAGS_5(sve2_fcvtlt_hs, TCG_CALL_NO_RWG,
                    void, ptr, ptr, ptr, ptr, i32)
 DEF_HELPER_FLAGS_5(sve2_fcvtlt_sd, TCG_CALL_NO_RWG,
                    void, ptr, ptr, ptr, ptr, i32)
+
+DEF_HELPER_FLAGS_5(flogb_h, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, ptr, i32)
+DEF_HELPER_FLAGS_5(flogb_s, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, ptr, i32)
+DEF_HELPER_FLAGS_5(flogb_d, TCG_CALL_NO_RWG, void, ptr, ptr, ptr, ptr, i32)
diff --git a/target/arm/sve.decode b/target/arm/sve.decode
index 5dcc79759e..5a1cceccb6 100644
--- a/target/arm/sve.decode
+++ b/target/arm/sve.decode
@@ -1588,3 +1588,6 @@ FCVTNT_sh       01100100 10 0010 00 101 ... ..... .....  @rd_pg_rn_e0
 FCVTLT_hs       01100100 10 0010 01 101 ... ..... .....  @rd_pg_rn_e0
 FCVTNT_ds       01100100 11 0010 10 101 ... ..... .....  @rd_pg_rn_e0
 FCVTLT_sd       01100100 11 0010 11 101 ... ..... .....  @rd_pg_rn_e0
+
+### SVE2 floating-point convert to integer
+FLOGB           01100101 00 011 esz:2 0101 pg:3 rn:5 rd:5  &rpr_esz
diff --git a/target/arm/sve_helper.c b/target/arm/sve_helper.c
index 8882393515..a051854984 100644
--- a/target/arm/sve_helper.c
+++ b/target/arm/sve_helper.c
@@ -4729,6 +4729,94 @@ DO_ZPZ_FP(sve_ucvt_dh, uint64_t,     , uint64_to_float16)
 DO_ZPZ_FP(sve_ucvt_ds, uint64_t,     , uint64_to_float32)
 DO_ZPZ_FP(sve_ucvt_dd, uint64_t,     , uint64_to_float64)
 
+static int16_t do_float16_logb_as_int(float16 a, float_status *s)
+{
+    /* Extract frac to the top of the uint32_t. */
+    uint32_t frac = (uint32_t)a << (16 + 6);
+    int16_t exp = extract32(a, 10, 5);
+
+    if (unlikely(exp == 0)) {
+        if (frac != 0) {
+            if (!get_flush_inputs_to_zero(s)) {
+                /* denormal: bias - fractional_zeros */
+                return -15 - clz32(frac);
+            }
+            /* flush to zero */
+            float_raise(float_flag_input_denormal, s);
+        }
+    } else if (unlikely(exp == 0x1f)) {
+        if (frac == 0) {
+            return INT16_MAX; /* infinity */
+        }
+    } else {
+        /* normal: exp - bias */
+        return exp - 15;
+    }
+    /* nan or zero */
+    float_raise(float_flag_invalid, s);
+    return INT16_MIN;
+}
+
+static int32_t do_float32_logb_as_int(float32 a, float_status *s)
+{
+    /* Extract frac to the top of the uint32_t. */
+    uint32_t frac = a << 9;
+    int32_t exp = extract32(a, 23, 8);
+
+    if (unlikely(exp == 0)) {
+        if (frac != 0) {
+            if (!get_flush_inputs_to_zero(s)) {
+                /* denormal: bias - fractional_zeros */
+                return -127 - clz32(frac);
+            }
+            /* flush to zero */
+            float_raise(float_flag_input_denormal, s);
+        }
+    } else if (unlikely(exp == 0xff)) {
+        if (frac == 0) {
+            return INT32_MAX; /* infinity */
+        }
+    } else {
+        /* normal: exp - bias */
+        return exp - 127;
+    }
+    /* nan or zero */
+    float_raise(float_flag_invalid, s);
+    return INT32_MIN;
+}
+
+static int64_t do_float64_logb_as_int(float64 a, float_status *s)
+{
+    /* Extract frac to the top of the uint64_t. */
+    uint64_t frac = a << 12;
+    int64_t exp = extract64(a, 52, 11);
+
+    if (unlikely(exp == 0)) {
+        if (frac != 0) {
+            if (!get_flush_inputs_to_zero(s)) {
+                /* denormal: bias - fractional_zeros */
+                return -1023 - clz64(frac);
+            }
+            /* flush to zero */
+            float_raise(float_flag_input_denormal, s);
+        }
+    } else if (unlikely(exp == 0x7ff)) {
+        if (frac == 0) {
+            return INT64_MAX; /* infinity */
+        }
+    } else {
+        /* normal: exp - bias */
+        return exp - 1023;
+    }
+    /* nan or zero */
+    float_raise(float_flag_invalid, s);
+    return INT64_MIN;
+}
+
+DO_ZPZ_FP(flogb_h, float16, H1_2, do_float16_logb_as_int)
+DO_ZPZ_FP(flogb_s, float32, H1_4, do_float32_logb_as_int)
+DO_ZPZ_FP(flogb_d, float64,     , do_float64_logb_as_int)
+
 #undef DO_ZPZ_FP
 
 static void do_fmla_zpzzz_h(void *vd, void *vn, void *vm, void *va, void *vg,
diff --git a/target/arm/translate-sve.c b/target/arm/translate-sve.c
index 0a2718c481..3ea51a73d3 100644
--- a/target/arm/translate-sve.c
+++ b/target/arm/translate-sve.c
@@ -8307,3 +8307,27 @@ static bool trans_FCVTXNT_ds(DisasContext *s, arg_rpr_esz *a)
     }
     return do_frint_mode(s, a, float_round_to_odd, gen_helper_sve2_fcvtnt_ds);
 }
+
+static bool trans_FLOGB(DisasContext *s, arg_rpr_esz *a)
+{
+    static gen_helper_gvec_3_ptr * const fns[] = {
+        NULL,               gen_helper_flogb_h,
+        gen_helper_flogb_s, gen_helper_flogb_d
+    };
+
+    if (!dc_isar_feature(aa64_sve2, s) || fns[a->esz] == NULL) {
+        return false;
+    }
+    if (sve_access_check(s)) {
+        TCGv_ptr status =
+            fpstatus_ptr(a->esz == MO_16 ? FPST_FPCR_F16 : FPST_FPCR);
+        unsigned vsz = vec_full_reg_size(s);
+
+        tcg_gen_gvec_3_ptr(vec_full_reg_offset(s, a->rd),
+                           vec_full_reg_offset(s, a->rn),
+                           pred_full_reg_offset(s, a->pg),
+                           status, vsz, vsz, 0, fns[a->esz]);
+        tcg_temp_free_ptr(status);
+    }
+    return true;
+}
-- 
2.25.1