tcg/mips: only enable ext8s/ext16s ops on MIPS32R2

On MIPS ext8s and ext16s ops are implemented with a dedicated
instruction only on MIPS32R2, otherwise the same kind of implementation
than at TCG level (shift left followed by shift right) is used.

Change that by only implementing the ext8s and ext16s ops on MIPS32R2 so
that optimizations can be done by the optimizer. Use an inline version to
avoid having to test again for MIPS32R2 instructions. Keep the shift
implementation for the ld/st routines.

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

tcg/mips/tcg-target.c

@@ -1515,10 +1515,10 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
         break;
 
     case INDEX_op_ext8s_i32:
-        tcg_out_ext8s(s, args[0], args[1]);
+        tcg_out_opc_reg(s, OPC_SEB, args[0], 0, args[1]);
         break;
     case INDEX_op_ext16s_i32:
-        tcg_out_ext16s(s, args[0], args[1]);
+        tcg_out_opc_reg(s, OPC_SEH, args[0], 0, args[1]);
         break;
 
     case INDEX_op_deposit_i32:

tcg/mips/tcg-target.h

@@ -105,8 +105,6 @@ extern bool use_mips32r2_instructions;
 #define TCG_TARGET_HAS_rem_i32          1
 #define TCG_TARGET_HAS_not_i32          1
 #define TCG_TARGET_HAS_nor_i32          1
-#define TCG_TARGET_HAS_ext8s_i32        1
-#define TCG_TARGET_HAS_ext16s_i32       1
 #define TCG_TARGET_HAS_andc_i32         0
 #define TCG_TARGET_HAS_orc_i32          0
 #define TCG_TARGET_HAS_eqv_i32          0
@@ -118,6 +116,8 @@ extern bool use_mips32r2_instructions;
 #define TCG_TARGET_HAS_bswap16_i32      use_mips32r2_instructions
 #define TCG_TARGET_HAS_bswap32_i32      use_mips32r2_instructions
 #define TCG_TARGET_HAS_deposit_i32      use_mips32r2_instructions
+#define TCG_TARGET_HAS_ext8s_i32        use_mips32r2_instructions
+#define TCG_TARGET_HAS_ext16s_i32       use_mips32r2_instructions
 #define TCG_TARGET_HAS_rot_i32          use_mips32r2_instructions
 
 /* optional instructions automatically implemented */