diff --git a/tcg/tcg.h b/tcg/tcg.h
index 3d004ba276..fbb3daf14c 100644
--- a/tcg/tcg.h
+++ b/tcg/tcg.h
@@ -417,20 +417,19 @@ static inline TCGCond tcg_high_cond(TCGCond c)
     }
 }
 
-#define TEMP_VAL_DEAD  0
-#define TEMP_VAL_REG   1
-#define TEMP_VAL_MEM   2
-#define TEMP_VAL_CONST 3
+typedef enum TCGTempVal {
+    TEMP_VAL_DEAD,
+    TEMP_VAL_REG,
+    TEMP_VAL_MEM,
+    TEMP_VAL_CONST,
+} TCGTempVal;
 
-/* XXX: optimize memory layout */
 typedef struct TCGTemp {
-    TCGType base_type;
-    TCGType type;
-    int val_type;
-    int reg;
-    tcg_target_long val;
-    int mem_reg;
-    intptr_t mem_offset;
+    unsigned int reg:8;
+    unsigned int mem_reg:8;
+    TCGTempVal val_type:8;
+    TCGType base_type:8;
+    TCGType type:8;
     unsigned int fixed_reg:1;
     unsigned int mem_coherent:1;
     unsigned int mem_allocated:1;
@@ -438,6 +437,9 @@ typedef struct TCGTemp {
                                   basic blocks. Otherwise, it is not
                                   preserved across basic blocks. */
     unsigned int temp_allocated:1; /* never used for code gen */
+
+    tcg_target_long val;
+    intptr_t mem_offset;
     const char *name;
 } TCGTemp;