MIPS: Don't use RID_GP as a scratch register.

src/lj_target_mips.h

@@ -28,6 +28,7 @@ enum {
   RID_MAX,
   RID_ZERO = RID_R0,
   RID_TMP = RID_RA,
+  RID_GP = RID_R28,
 
   /* Calling conventions. */
   RID_RET = RID_R2,
@@ -62,10 +63,10 @@ enum {
 
 /* -- Register sets ------------------------------------------------------- */
 
-/* Make use of all registers, except ZERO, TMP, SP, SYS1, SYS2 and JGL. */
+/* Make use of all registers, except ZERO, TMP, SP, SYS1, SYS2, JGL and GP. */
 #define RSET_FIXED \
   (RID2RSET(RID_ZERO)|RID2RSET(RID_TMP)|RID2RSET(RID_SP)|\
-   RID2RSET(RID_SYS1)|RID2RSET(RID_SYS2)|RID2RSET(RID_JGL))
+   RID2RSET(RID_SYS1)|RID2RSET(RID_SYS2)|RID2RSET(RID_JGL)|RID2RSET(RID_GP))
 #define RSET_GPR	(RSET_RANGE(RID_MIN_GPR, RID_MAX_GPR) - RSET_FIXED)
 #define RSET_FPR \
   (RID2RSET(RID_F0)|RID2RSET(RID_F2)|RID2RSET(RID_F4)|RID2RSET(RID_F6)|\
@@ -77,7 +78,7 @@ enum {
 
 #define RSET_SCRATCH_GPR \
   (RSET_RANGE(RID_R1, RID_R15+1)|\
-   RID2RSET(RID_R24)|RID2RSET(RID_R25)|RID2RSET(RID_R28))
+   RID2RSET(RID_R24)|RID2RSET(RID_R25))
 #define RSET_SCRATCH_FPR \
   (RID2RSET(RID_F0)|RID2RSET(RID_F2)|RID2RSET(RID_F4)|RID2RSET(RID_F6)|\
    RID2RSET(RID_F8)|RID2RSET(RID_F10)|RID2RSET(RID_F12)|RID2RSET(RID_F14)|\