target-ppc: Optimize rlwnm MB=0 ME=31

Optimize the special case of rlwnm where MB=0 and ME=31.  This can
be implemented using a ROTL.
Suggested-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NTom Musta <tommusta@gmail.com>
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAlexander Graf <agraf@suse.de>

target-ppc/translate.c

@@ -1721,37 +1721,49 @@ static void gen_rlwinm(DisasContext *ctx)
 static void gen_rlwnm(DisasContext *ctx)
 {
     uint32_t mb, me;
-    TCGv t0;
-#if defined(TARGET_PPC64)
-    TCGv t1;
-#endif
-
     mb = MB(ctx->opcode);
     me = ME(ctx->opcode);
-    t0 = tcg_temp_new();
-    tcg_gen_andi_tl(t0, cpu_gpr[rB(ctx->opcode)], 0x1f);
+
+    if (likely(mb == 0 && me == 31)) {
+        TCGv_i32 t0, t1;
+        t0 = tcg_temp_new_i32();
+        t1 = tcg_temp_new_i32();
+        tcg_gen_trunc_tl_i32(t0, cpu_gpr[rB(ctx->opcode)]);
+        tcg_gen_trunc_tl_i32(t1, cpu_gpr[rS(ctx->opcode)]);
+        tcg_gen_andi_i32(t0, t0, 0x1f);
+        tcg_gen_rotl_i32(t1, t1, t0);
+        tcg_gen_extu_i32_tl(cpu_gpr[rA(ctx->opcode)], t1);
+        tcg_temp_free_i32(t0);
+        tcg_temp_free_i32(t1);
+    } else {
+        TCGv t0;
 #if defined(TARGET_PPC64)
-    t1 = tcg_temp_new_i64();
-    tcg_gen_deposit_i64(t1, cpu_gpr[rS(ctx->opcode)],
-        cpu_gpr[rS(ctx->opcode)], 32, 32);
-    tcg_gen_rotl_i64(t0, t1, t0);
-    tcg_temp_free_i64(t1);
-#else
-    tcg_gen_rotl_i32(t0, cpu_gpr[rS(ctx->opcode)], t0);
+        TCGv t1;
 #endif
-    if (unlikely(mb != 0 || me != 31)) {
+
+        t0 = tcg_temp_new();
+        tcg_gen_andi_tl(t0, cpu_gpr[rB(ctx->opcode)], 0x1f);
 #if defined(TARGET_PPC64)
-        mb += 32;
-        me += 32;
+        t1 = tcg_temp_new_i64();
+        tcg_gen_deposit_i64(t1, cpu_gpr[rS(ctx->opcode)],
+                            cpu_gpr[rS(ctx->opcode)], 32, 32);
+        tcg_gen_rotl_i64(t0, t1, t0);
+        tcg_temp_free_i64(t1);
+#else
+        tcg_gen_rotl_i32(t0, cpu_gpr[rS(ctx->opcode)], t0);
 #endif
-        tcg_gen_andi_tl(cpu_gpr[rA(ctx->opcode)], t0, MASK(mb, me));
-    } else {
+        if (unlikely(mb != 0 || me != 31)) {
 #if defined(TARGET_PPC64)
-        tcg_gen_andi_tl(t0, t0, MASK(32, 63));
+            mb += 32;
+            me += 32;
 #endif
-        tcg_gen_mov_tl(cpu_gpr[rA(ctx->opcode)], t0);
+            tcg_gen_andi_tl(cpu_gpr[rA(ctx->opcode)], t0, MASK(mb, me));
+        } else {
+            tcg_gen_andi_tl(t0, t0, MASK(32, 63));
+            tcg_gen_mov_tl(cpu_gpr[rA(ctx->opcode)], t0);
+        }
+        tcg_temp_free(t0);
     }
-    tcg_temp_free(t0);
     if (unlikely(Rc(ctx->opcode) != 0))
         gen_set_Rc0(ctx, cpu_gpr[rA(ctx->opcode)]);
 }