Do not initialize cpu_R[0], as this should be totally unused.
The cpu_for_read and cpu_for_write functions use a local temp.

Tested-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/microblaze/translate.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/target/microblaze/translate.c b/target/microblaze/translate.c
index 8f69ca50b2..8c287457a9 100644
--- a/target/microblaze/translate.c
+++ b/target/microblaze/translate.c
@@ -1842,7 +1842,13 @@ void mb_tcg_init(void)
     static const struct {
         TCGv_i32 *var; int ofs; char name[8];
     } i32s[] = {
-        R(0),  R(1),  R(2),  R(3),  R(4),  R(5),  R(6),  R(7),
+        /*
+         * Note that r0 is handled specially in reg_for_read
+         * and reg_for_write.  Nothing should touch cpu_R[0].
+         * Leave that element NULL, which will assert quickly
+         * inside the tcg generator functions.
+         */
+               R(1),  R(2),  R(3),  R(4),  R(5),  R(6),  R(7),
         R(8),  R(9),  R(10), R(11), R(12), R(13), R(14), R(15),
         R(16), R(17), R(18), R(19), R(20), R(21), R(22), R(23),
         R(24), R(25), R(26), R(27), R(28), R(29), R(30), R(31),
-- 
2.25.1