target/arm: Implement SVE prefetches

Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRichard Henderson <richard.henderson@linaro.org>
Message-id: 20180627043328.11531-13-richard.henderson@linaro.org
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

target/arm/sve.decode

@@ -794,6 +794,29 @@ LD1RQ_zprr      1010010 .. 00 ..... 000 ... ..... ..... \
 LD1RQ_zpri      1010010 .. 00 0.... 001 ... ..... ..... \
                 @rpri_load_msz nreg=0
 
+# SVE 32-bit gather prefetch (scalar plus 32-bit scaled offsets)
+PRF             1000010 00 -1 ----- 0-- --- ----- 0 ----
+
+# SVE 32-bit gather prefetch (vector plus immediate)
+PRF             1000010 -- 00 ----- 111 --- ----- 0 ----
+
+# SVE contiguous prefetch (scalar plus immediate)
+PRF             1000010 11 1- ----- 0-- --- ----- 0 ----
+
+# SVE contiguous prefetch (scalar plus scalar)
+PRF_rr          1000010 -- 00 rm:5 110 --- ----- 0 ----
+
+### SVE Memory 64-bit Gather Group
+
+# SVE 64-bit gather prefetch (scalar plus 64-bit scaled offsets)
+PRF             1100010 00 11 ----- 1-- --- ----- 0 ----
+
+# SVE 64-bit gather prefetch (scalar plus unpacked 32-bit scaled offsets)
+PRF             1100010 00 -1 ----- 0-- --- ----- 0 ----
+
+# SVE 64-bit gather prefetch (vector plus immediate)
+PRF             1100010 -- 00 ----- 111 --- ----- 0 ----
+
 ### SVE Memory Store Group
 
 # SVE store predicate register

target/arm/translate-sve.c

@@ -4303,3 +4303,24 @@ static bool trans_ST1_zprz(DisasContext *s, arg_ST1_zprz *a, uint32_t insn)
                cpu_reg_sp(s, a->rn), fn);
     return true;
 }
+
+/*
+ * Prefetches
+ */
+
+static bool trans_PRF(DisasContext *s, arg_PRF *a, uint32_t insn)
+{
+    /* Prefetch is a nop within QEMU.  */
+    sve_access_check(s);
+    return true;
+}
+
+static bool trans_PRF_rr(DisasContext *s, arg_PRF_rr *a, uint32_t insn)
+{
+    if (a->rm == 31) {
+        return false;
+    }
+    /* Prefetch is a nop within QEMU.  */
+    sve_access_check(s);
+    return true;
+}