target/arm: Promote consecutive memory ops for aa32

For a sequence of loads or stores from a single register,
little-endian operations can be promoted to an 8-byte op.
This can reduce the number of operations by a factor of 8.
Signed-off-by: NRichard Henderson <richard.henderson@linaro.org>
Message-id: 20181011205206.3552-20-richard.henderson@linaro.org
Reviewed-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

target/arm/translate.c

@@ -5011,6 +5011,16 @@ static int disas_neon_ls_insn(DisasContext *s, uint32_t insn)
         if (size == 3 && (interleave | spacing) != 1) {
             return 1;
         }
+        /* For our purposes, bytes are always little-endian.  */
+        if (size == 0) {
+            endian = MO_LE;
+        }
+        /* Consecutive little-endian elements from a single register
+         * can be promoted to a larger little-endian operation.
+         */
+        if (interleave == 1 && endian == MO_LE) {
+            size = 3;
+        }
         tmp64 = tcg_temp_new_i64();
         addr = tcg_temp_new_i32();
         tmp2 = tcg_const_i32(1 << size);