target-arm: Add support for PKHxx in thumb2

The PKHxx instructions were not recognized by the thumb2 decoder. The
solution provided in this changeset is identical to the arm-mode
implementation.
Signed-off-by: Johan Bengtsson <teofrastius@gmail.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Nathan Froyd <froydnj@codesourcery.com>

target-arm/translate.c

@@ -7601,7 +7601,33 @@ static int disas_thumb2_insn(CPUState *env, DisasContext *s, uint16_t insn_hw1)
             }
         }
         break;
-    case 5: /* Data processing register constant shift.  */
+    case 5:
+
+        op = (insn >> 21) & 0xf;
+        if (op == 6) {
+            /* Halfword pack.  */
+            tmp = load_reg(s, rn);
+            tmp2 = load_reg(s, rm);
+            shift = ((insn >> 10) & 0x1c) | ((insn >> 6) & 0x3);
+            if (insn & (1 << 5)) {
+                /* pkhtb */
+                if (shift == 0)
+                    shift = 31;
+                tcg_gen_sari_i32(tmp2, tmp2, shift);
+                tcg_gen_andi_i32(tmp, tmp, 0xffff0000);
+                tcg_gen_ext16u_i32(tmp2, tmp2);
+            } else {
+                /* pkhbt */
+                if (shift)
+                    tcg_gen_shli_i32(tmp2, tmp2, shift);
+                tcg_gen_ext16u_i32(tmp, tmp);
+                tcg_gen_andi_i32(tmp2, tmp2, 0xffff0000);
+            }
+            tcg_gen_or_i32(tmp, tmp, tmp2);
+            dead_tmp(tmp2);
+            store_reg(s, rd, tmp);
+        } else {
+            /* Data processing register constant shift.  */
             if (rn == 15) {
                 tmp = new_tmp();
                 tcg_gen_movi_i32(tmp, 0);
@@ -7609,7 +7635,7 @@ static int disas_thumb2_insn(CPUState *env, DisasContext *s, uint16_t insn_hw1)
                 tmp = load_reg(s, rn);
             }
             tmp2 = load_reg(s, rm);
-        op = (insn >> 21) & 0xf;
+
             shiftop = (insn >> 4) & 3;
             shift = ((insn >> 6) & 3) | ((insn >> 10) & 0x1c);
             conds = (insn & (1 << 20)) != 0;
@@ -7623,6 +7649,7 @@ static int disas_thumb2_insn(CPUState *env, DisasContext *s, uint16_t insn_hw1)
             } else {
                 dead_tmp(tmp);
             }
+        }
         break;
     case 13: /* Misc data processing.  */
         op = ((insn >> 22) & 6) | ((insn >> 7) & 1);