tcg: Add TCGV_UNUSED_PTR, TCGV_IS_UNUSED_PTR, TCGV_EQUAL_PTR

We have macros for marking TCGv values as unused, checking if they
are unused and comparing them to each other. However these only exist
for TCGv_i32 and TCGv_i64; add them for TCGv_ptr as well.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <rth@twiddle.net>

tcg/tcg.h

@@ -324,13 +324,16 @@ typedef int TCGv_i64;
 
 #define TCGV_EQUAL_I32(a, b) (GET_TCGV_I32(a) == GET_TCGV_I32(b))
 #define TCGV_EQUAL_I64(a, b) (GET_TCGV_I64(a) == GET_TCGV_I64(b))
+#define TCGV_EQUAL_PTR(a, b) (GET_TCGV_PTR(a) == GET_TCGV_PTR(b))
 
 /* Dummy definition to avoid compiler warnings.  */
 #define TCGV_UNUSED_I32(x) x = MAKE_TCGV_I32(-1)
 #define TCGV_UNUSED_I64(x) x = MAKE_TCGV_I64(-1)
+#define TCGV_UNUSED_PTR(x) x = MAKE_TCGV_PTR(-1)
 
 #define TCGV_IS_UNUSED_I32(x) (GET_TCGV_I32(x) == -1)
 #define TCGV_IS_UNUSED_I64(x) (GET_TCGV_I64(x) == -1)
+#define TCGV_IS_UNUSED_PTR(x) (GET_TCGV_PTR(x) == -1)
 
 /* call flags */
 /* Helper does not read globals (either directly or through an exception). It