target/ppc: Use aesdec_ISB_ISR_AK_IMC

This implements the VNCIPHER instruction.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

target/ppc/int_helper.c

@@ -2947,22 +2947,11 @@ void helper_vcipherlast(ppc_avr_t *r, ppc_avr_t *a, ppc_avr_t *b)
 
 void helper_vncipher(ppc_avr_t *r, ppc_avr_t *a, ppc_avr_t *b)
 {
-    /* This differs from what is written in ISA V2.07.  The RTL is */
-    /* incorrect and will be fixed in V2.07B.                      */
-    int i;
-    ppc_avr_t tmp;
-
-    VECTOR_FOR_INORDER_I(i, u8) {
-        tmp.VsrB(i) = b->VsrB(i) ^ AES_isbox[a->VsrB(AES_ishifts[i])];
-    }
+    AESState *ad = (AESState *)r;
+    AESState *st = (AESState *)a;
+    AESState *rk = (AESState *)b;
 
-    VECTOR_FOR_INORDER_I(i, u32) {
-        r->VsrW(i) =
-            AES_imc[tmp.VsrB(4 * i + 0)][0] ^
-            AES_imc[tmp.VsrB(4 * i + 1)][1] ^
-            AES_imc[tmp.VsrB(4 * i + 2)][2] ^
-            AES_imc[tmp.VsrB(4 * i + 3)][3];
-    }
+    aesdec_ISB_ISR_AK_IMC(ad, st, rk, true);
 }
 
 void helper_vncipherlast(ppc_avr_t *r, ppc_avr_t *a, ppc_avr_t *b)