tcg/aarch64: limit mul_vec size

In AdvSIMD we can only do 32x32 integer multiples although SVE is
capable of larger 64 bit multiples. As a result we can end up
generating invalid opcodes. Fix this by only reprting we can emit
mul vector ops if the size is small enough.

Fixes a crash on:

  sve-all-short-v8.3+sve@vq3/insn_mul_z_zi___INC.risu.bin

When running on AArch64 hardware.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20180719154248.29669-1-alex.bennee@linaro.org>
[rth: Removed the tcg_debug_assert -- there are plenty of other
cases that we do not diagnose within the insn encoding helpers.]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
diff --git a/tcg/aarch64/tcg-target.inc.c b/tcg/aarch64/tcg-target.inc.c
index 4562d36..083592a 100644
--- a/tcg/aarch64/tcg-target.inc.c
+++ b/tcg/aarch64/tcg-target.inc.c
@@ -2219,7 +2219,6 @@
     switch (opc) {
     case INDEX_op_add_vec:
     case INDEX_op_sub_vec:
-    case INDEX_op_mul_vec:
     case INDEX_op_and_vec:
     case INDEX_op_or_vec:
     case INDEX_op_xor_vec:
@@ -2232,6 +2231,8 @@
     case INDEX_op_shri_vec:
     case INDEX_op_sari_vec:
         return 1;
+    case INDEX_op_mul_vec:
+        return vece < MO_64;
 
     default:
         return 0;