target/i386: Use tcg_gen_ext_tl

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c
index 18d06ab..587d886 100644
--- a/target/i386/tcg/translate.c
+++ b/target/i386/tcg/translate.c
@@ -701,33 +701,11 @@
 
 static TCGv gen_ext_tl(TCGv dst, TCGv src, MemOp size, bool sign)
 {
-    switch (size) {
-    case MO_8:
-        if (sign) {
-            tcg_gen_ext8s_tl(dst, src);
-        } else {
-            tcg_gen_ext8u_tl(dst, src);
-        }
-        return dst;
-    case MO_16:
-        if (sign) {
-            tcg_gen_ext16s_tl(dst, src);
-        } else {
-            tcg_gen_ext16u_tl(dst, src);
-        }
-        return dst;
-#ifdef TARGET_X86_64
-    case MO_32:
-        if (sign) {
-            tcg_gen_ext32s_tl(dst, src);
-        } else {
-            tcg_gen_ext32u_tl(dst, src);
-        }
-        return dst;
-#endif
-    default:
+    if (size == MO_TL) {
         return src;
     }
+    tcg_gen_ext_tl(dst, src, size | (sign ? MO_SIGN : 0));
+    return dst;
 }
 
 static void gen_extu(MemOp ot, TCGv reg)