target/arm: Convert Neon 3-reg-same VADD/VSUB to decodetree

Convert the Neon 3-reg-same VADD and VSUB insns to decodetree.

Note that we don't need the neon_3r_sizes[op] check here because all
size values are OK for VADD and VSUB; we'll add this when we convert
the first insn that has size restrictions.

For this we need one of the GVecGen*Fn typedefs currently in
translate-a64.h; move them all to translate.h as a block so they
are visible to the 32-bit decoder.

Backports commit a4e143ac5b9185f670d2f17ee9cc1a430047cb65 from qemu

qemu/target/arm/neon-dp.decode

@@ -18,6 +18,10 @@
 #
 # This file is processed by scripts/decodetree.py
 #
+# VFP/Neon register fields; same as vfp.decode
+%vm_dp  5:1 0:4
+%vn_dp  7:1 16:4
+%vd_dp  22:1 12:4
 
 # Encodings for Neon data processing instructions where the T32 encoding
 # is a simple transformation of the A32 encoding.
@@ -27,3 +31,16 @@
 #   0b111p_1111_qqqq_qqqq_qqqq_qqqq_qqqq_qqqq
 # This file works on the A32 encoding only; calling code for T32 has to
 # transform the insn into the A32 version first.
+
+######################################################################
+# 3-reg-same grouping:
+# 1111 001 U 0 D sz:2 Vn:4 Vd:4 opc:4 N Q M op Vm:4
+######################################################################
+
+&3same vm vn vd q size
+
+@3same           .... ... . . . size:2 .... .... .... . q:1 . . .... \
+                 &3same vm=%vm_dp vn=%vn_dp vd=%vd_dp
+
+VADD_3s          1111 001 0 0 . .. .... .... 1000 . . . 0 .... @3same
+VSUB_3s          1111 001 1 0 . .. .... .... 1000 . . . 0 .... @3same

qemu/target/arm/translate-a64.h

@@ -116,13 +116,4 @@ static inline int vec_full_reg_size(DisasContext *s)
 
 bool disas_sve(DisasContext *, uint32_t);
 
-/* Note that the gvec expanders operate on offsets + sizes.  */
-typedef void GVecGen2Fn(TCGContext *, unsigned, uint32_t, uint32_t, uint32_t, uint32_t);
-typedef void GVecGen2iFn(TCGContext *, unsigned, uint32_t, uint32_t, int64_t,
-                         uint32_t, uint32_t);
-typedef void GVecGen3Fn(TCGContext *, unsigned, uint32_t, uint32_t,
-                        uint32_t, uint32_t, uint32_t);
-typedef void GVecGen4Fn(TCGContext *, unsigned, uint32_t, uint32_t, uint32_t,
-                        uint32_t, uint32_t, uint32_t);
-
 #endif /* TARGET_ARM_TRANSLATE_A64_H */

qemu/target/arm/translate-neon.inc.c

@@ -572,3 +572,42 @@ static bool trans_VLDST_single(DisasContext *s, arg_VLDST_single *a)
 
     return true;
 }
+
+static bool do_3same(DisasContext *s, arg_3same *a, GVecGen3Fn fn)
+{
+    int vec_size = a->q ? 16 : 8;
+    int rd_ofs = neon_reg_offset(a->vd, 0);
+    int rn_ofs = neon_reg_offset(a->vn, 0);
+    int rm_ofs = neon_reg_offset(a->vm, 0);
+    TCGContext *tcg_ctx = s->uc->tcg_ctx;
+
+    if (!arm_dc_feature(s, ARM_FEATURE_NEON)) {
+        return false;
+    }
+
+    /* UNDEF accesses to D16-D31 if they don't exist. */
+    if (!dc_isar_feature(aa32_simd_r32, s) &&
+        ((a->vd | a->vn | a->vm) & 0x10)) {
+        return false;
+    }
+
+    if ((a->vn | a->vm | a->vd) & a->q) {
+        return false;
+    }
+
+    if (!vfp_access_check(s)) {
+        return true;
+    }
+
+    fn(tcg_ctx, a->size, rd_ofs, rn_ofs, rm_ofs, vec_size, vec_size);
+    return true;
+}
+
+#define DO_3SAME(INSN, FUNC)                                            \
+    static bool trans_##INSN##_3s(DisasContext *s, arg_3same *a)        \
+    {                                                                   \
+        return do_3same(s, a, FUNC);                                    \
+    }
+
+DO_3SAME(VADD, tcg_gen_gvec_add)
+DO_3SAME(VSUB, tcg_gen_gvec_sub)

qemu/target/arm/translate.c

@@ -5016,16 +5016,6 @@ static int disas_neon_data_insn(DisasContext *s, uint32_t insn)
             }
             return 0;
 
-        case NEON_3R_VADD_VSUB:
-            if (u) {
-                tcg_gen_gvec_sub(tcg_ctx, size, rd_ofs, rn_ofs, rm_ofs,
-                                 vec_size, vec_size);
-            } else {
-                tcg_gen_gvec_add(tcg_ctx, size, rd_ofs, rn_ofs, rm_ofs,
-                                 vec_size, vec_size);
-            }
-            return 0;
-
         case NEON_3R_VQADD:
             tcg_gen_gvec_4(tcg_ctx, rd_ofs, offsetof(CPUARMState, vfp.qc),
                            rn_ofs, rm_ofs, vec_size, vec_size,
@@ -5101,6 +5091,10 @@ static int disas_neon_data_insn(DisasContext *s, uint32_t insn)
             tcg_gen_gvec_3(tcg_ctx, rd_ofs, rm_ofs, rn_ofs, vec_size, vec_size,
                            u ? &ushl_op[size] : &sshl_op[size]);
             return 0;
+
+        case NEON_3R_VADD_VSUB:
+            /* Already handled by decodetree */
+            return 1;
         }
 
         if (size == 3) {

qemu/target/arm/translate.h

@@ -312,4 +312,13 @@ void gen_sshl_i64(TCGContext* tcg_ctx, TCGv_i64 d, TCGv_i64 a, TCGv_i64 b);
 #define dc_isar_feature(name, ctx) \
     ({ DisasContext *ctx_ = (ctx); isar_feature_##name(ctx_->isar); })
 
+/* Note that the gvec expanders operate on offsets + sizes.  */
+typedef void GVecGen2Fn(TCGContext *, unsigned, uint32_t, uint32_t, uint32_t, uint32_t);
+typedef void GVecGen2iFn(TCGContext *, unsigned, uint32_t, uint32_t, int64_t,
+                         uint32_t, uint32_t);
+typedef void GVecGen3Fn(TCGContext *, unsigned, uint32_t, uint32_t,
+                        uint32_t, uint32_t, uint32_t);
+typedef void GVecGen4Fn(TCGContext *, unsigned, uint32_t, uint32_t, uint32_t,
+                        uint32_t, uint32_t, uint32_t);
+
 #endif /* TARGET_ARM_TRANSLATE_H */