target/arm: Implement SVE2p1 WHILE (predicate as counter)

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250704142112.1018902-80-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

4 files changed, 84 insertions, 5 deletions

diff --git a/target/arm/tcg/helper-sve.h b/target/arm/tcg/helper-sve.h
index eac23e7..74029c6 100644
--- a/target/arm/tcg/helper-sve.h
+++ b/target/arm/tcg/helper-sve.h
@@ -944,6 +944,9 @@ DEF_HELPER_FLAGS_3(sve_whileg, TCG_CALL_NO_RWG, i32, ptr, i32, i32)
 DEF_HELPER_FLAGS_3(sve_while2l, TCG_CALL_NO_RWG, i32, ptr, i32, i32)
 DEF_HELPER_FLAGS_3(sve_while2g, TCG_CALL_NO_RWG, i32, ptr, i32, i32)
 
+DEF_HELPER_FLAGS_3(sve_whilecl, TCG_CALL_NO_RWG, i32, ptr, i32, i32)
+DEF_HELPER_FLAGS_3(sve_whilecg, TCG_CALL_NO_RWG, i32, ptr, i32, i32)
+
 DEF_HELPER_FLAGS_4(sve_subri_b, TCG_CALL_NO_RWG, void, ptr, ptr, i64, i32)
 DEF_HELPER_FLAGS_4(sve_subri_h, TCG_CALL_NO_RWG, void, ptr, ptr, i64, i32)
 DEF_HELPER_FLAGS_4(sve_subri_s, TCG_CALL_NO_RWG, void, ptr, ptr, i64, i32)
diff --git a/target/arm/tcg/sve.decode b/target/arm/tcg/sve.decode
index 968b2a5..389a72d 100644
--- a/target/arm/tcg/sve.decode
+++ b/target/arm/tcg/sve.decode
@@ -59,6 +59,8 @@
 
 %rn_ax2         6:4 !function=times_2
 
+%pnd            0:3 !function=plus_8
+
 ###########################################################################
 # Named attribute sets.  These are used to make nice(er) names
 # when creating helpers common to those for the individual
@@ -804,6 +806,15 @@ WHILE_ptr       00100101 esz:2 1 rm:5 001 100 rn:5 rw:1 rd:4
 WHILE_lt_pair   00100101 .. 1 ..... 0101 . 1 ..... 1 ... .  @while_pair
 WHILE_gt_pair   00100101 .. 1 ..... 0101 . 0 ..... 1 ... .  @while_pair
 
+# SVE2.1 predicate as count
+@while_cnt      ........ esz:2 . rm:5 .... u:1 . rn:5 . eq:1 ... \
+                &while rd=%pnd sf=1
+
+WHILE_lt_cnt2   00100101 .. 1 ..... 0100 . 1 ..... 1 . ...  @while_cnt
+WHILE_lt_cnt4   00100101 .. 1 ..... 0110 . 1 ..... 1 . ...  @while_cnt
+WHILE_gt_cnt2   00100101 .. 1 ..... 0100 . 0 ..... 1 . ...  @while_cnt
+WHILE_gt_cnt4   00100101 .. 1 ..... 0110 . 0 ..... 1 . ...  @while_cnt
+
 ### SVE Integer Wide Immediate - Unpredicated Group
 
 # SVE broadcast floating-point immediate (unpredicated)
diff --git a/target/arm/tcg/sve_helper.c b/target/arm/tcg/sve_helper.c
index 30394f4..713642d 100644
--- a/target/arm/tcg/sve_helper.c
+++ b/target/arm/tcg/sve_helper.c
@@ -4090,6 +4090,29 @@ uint64_t HELPER(sve_cntp)(void *vn, void *vg, uint32_t pred_desc)
     return sum;
 }
 
+/* C.f. Arm pseudocode EncodePredCount */
+static uint64_t encode_pred_count(uint32_t elements, uint32_t count,
+                                  uint32_t esz, bool invert)
+{
+    uint32_t pred;
+
+    if (count == 0) {
+        return 0;
+    }
+    if (invert) {
+        count = elements - count;
+    } else if (count == elements) {
+        count = 0;
+        invert = true;
+    }
+
+    pred = (count << 1) | 1;
+    pred <<= esz;
+    pred |= invert << 15;
+
+    return pred;
+}
+
 /* C.f. Arm pseudocode PredCountTest */
 static uint32_t pred_count_test(uint32_t elements, uint32_t count, bool invert)
 {
@@ -4159,6 +4182,21 @@ uint32_t HELPER(sve_while2l)(void *vd, uint32_t count, uint32_t pred_desc)
     return pred_count_test(2 * oprbits, count, false);
 }
 
+uint32_t HELPER(sve_whilecl)(void *vd, uint32_t count, uint32_t pred_desc)
+{
+    uint32_t pl = FIELD_EX32(pred_desc, PREDDESC, OPRSZ);
+    uint32_t esz = FIELD_EX32(pred_desc, PREDDESC, ESZ);
+    uint32_t scale = FIELD_EX32(pred_desc, PREDDESC, DATA);
+    uint32_t vl = pl * 8;
+    uint32_t elements = (vl >> esz) << scale;
+    ARMPredicateReg *d = vd;
+
+    *d = (ARMPredicateReg) {
+        .p[0] = encode_pred_count(elements, count, esz, false)
+    };
+    return pred_count_test(elements, count, false);
+}
+
 /* D must be cleared on entry. */
 static void do_whileg(ARMPredicateReg *d, uint64_t esz_mask,
                       uint32_t count, uint32_t oprbits)
@@ -4212,6 +4250,21 @@ uint32_t HELPER(sve_while2g)(void *vd, uint32_t count, uint32_t pred_desc)
     return pred_count_test(2 * oprbits, count, true);
 }
 
+uint32_t HELPER(sve_whilecg)(void *vd, uint32_t count, uint32_t pred_desc)
+{
+    uint32_t pl = FIELD_EX32(pred_desc, PREDDESC, OPRSZ);
+    uint32_t esz = FIELD_EX32(pred_desc, PREDDESC, ESZ);
+    uint32_t scale = FIELD_EX32(pred_desc, PREDDESC, DATA);
+    uint32_t vl = pl * 8;
+    uint32_t elements = (vl >> esz) << scale;
+    ARMPredicateReg *d = vd;
+
+    *d = (ARMPredicateReg) {
+        .p[0] = encode_pred_count(elements, count, esz, true)
+    };
+    return pred_count_test(elements, count, true);
+}
+
 /* Recursive reduction on a function;
  * C.f. the ARM ARM function ReducePredicated.
  *
diff --git a/target/arm/tcg/translate-sve.c b/target/arm/tcg/translate-sve.c
index de6ffe7..c93dca2 100644
--- a/target/arm/tcg/translate-sve.c
+++ b/target/arm/tcg/translate-sve.c
@@ -3110,7 +3110,7 @@ static bool trans_CTERM(DisasContext *s, arg_CTERM *a)
 
 typedef void gen_while_fn(TCGv_i32, TCGv_ptr, TCGv_i32, TCGv_i32);
 static bool do_WHILE(DisasContext *s, arg_while *a,
-                     bool lt, int scale, gen_while_fn *fn)
+                     bool lt, int scale, int data, gen_while_fn *fn)
 {
     TCGv_i64 op0, op1, t0, t1, tmax;
     TCGv_i32 t2;
@@ -3196,6 +3196,7 @@ static bool do_WHILE(DisasContext *s, arg_while *a,
 
     desc = FIELD_DP32(desc, PREDDESC, OPRSZ, vsz / 8);
     desc = FIELD_DP32(desc, PREDDESC, ESZ, a->esz);
+    desc = FIELD_DP32(desc, PREDDESC, DATA, data);
 
     ptr = tcg_temp_new_ptr();
     tcg_gen_addi_ptr(ptr, tcg_env, pred_full_reg_offset(s, a->rd));
@@ -3206,13 +3207,24 @@ static bool do_WHILE(DisasContext *s, arg_while *a,
     return true;
 }
 
-TRANS_FEAT(WHILE_lt, aa64_sve, do_WHILE, a, true, 0, gen_helper_sve_whilel)
-TRANS_FEAT(WHILE_gt, aa64_sve2, do_WHILE, a, false, 0, gen_helper_sve_whileg)
+TRANS_FEAT(WHILE_lt, aa64_sve, do_WHILE,
+           a, true, 0, 0, gen_helper_sve_whilel)
+TRANS_FEAT(WHILE_gt, aa64_sve2, do_WHILE,
+           a, false, 0, 0, gen_helper_sve_whileg)
 
 TRANS_FEAT(WHILE_lt_pair, aa64_sme2_or_sve2p1, do_WHILE,
-           a, true, 1, gen_helper_sve_while2l)
+           a, true, 1, 0, gen_helper_sve_while2l)
 TRANS_FEAT(WHILE_gt_pair, aa64_sme2_or_sve2p1, do_WHILE,
-           a, false, 1, gen_helper_sve_while2g)
+           a, false, 1, 0, gen_helper_sve_while2g)
+
+TRANS_FEAT(WHILE_lt_cnt2, aa64_sme2_or_sve2p1, do_WHILE,
+           a, true, 1, 1, gen_helper_sve_whilecl)
+TRANS_FEAT(WHILE_lt_cnt4, aa64_sme2_or_sve2p1, do_WHILE,
+           a, true, 2, 2, gen_helper_sve_whilecl)
+TRANS_FEAT(WHILE_gt_cnt2, aa64_sme2_or_sve2p1, do_WHILE,
+           a, false, 1, 1, gen_helper_sve_whilecg)
+TRANS_FEAT(WHILE_gt_cnt4, aa64_sme2_or_sve2p1, do_WHILE,
+           a, false, 2, 2, gen_helper_sve_whilecg)
 
 static bool trans_WHILE_ptr(DisasContext *s, arg_WHILE_ptr *a)
 {