diff --git a/tcg/optimize.c b/tcg/optimize.c
index 7eb5eb1..98c7e3f 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -92,81 +92,10 @@ static void reset_temp(TCGArg temp, int nb_temps, int nb_globals)
     }
 }
 
-static int op_bits(int op)
+static int op_bits(enum TCGOpcode op)
 {
-    switch (op) {
-    case INDEX_op_mov_i32:
-    case INDEX_op_add_i32:
-    case INDEX_op_sub_i32:
-    case INDEX_op_mul_i32:
-    case INDEX_op_and_i32:
-    case INDEX_op_or_i32:
-    case INDEX_op_xor_i32:
-    case INDEX_op_shl_i32:
-    case INDEX_op_shr_i32:
-    case INDEX_op_sar_i32:
-#ifdef TCG_TARGET_HAS_rot_i32
-    case INDEX_op_rotl_i32:
-    case INDEX_op_rotr_i32:
-#endif
-#ifdef TCG_TARGET_HAS_not_i32
-    case INDEX_op_not_i32:
-#endif
-#ifdef TCG_TARGET_HAS_ext8s_i32
-    case INDEX_op_ext8s_i32:
-#endif
-#ifdef TCG_TARGET_HAS_ext16s_i32
-    case INDEX_op_ext16s_i32:
-#endif
-#ifdef TCG_TARGET_HAS_ext8u_i32
-    case INDEX_op_ext8u_i32:
-#endif
-#ifdef TCG_TARGET_HAS_ext16u_i32
-    case INDEX_op_ext16u_i32:
-#endif
-        return 32;
-#if TCG_TARGET_REG_BITS == 64
-    case INDEX_op_mov_i64:
-    case INDEX_op_add_i64:
-    case INDEX_op_sub_i64:
-    case INDEX_op_mul_i64:
-    case INDEX_op_and_i64:
-    case INDEX_op_or_i64:
-    case INDEX_op_xor_i64:
-    case INDEX_op_shl_i64:
-    case INDEX_op_shr_i64:
-    case INDEX_op_sar_i64:
-#ifdef TCG_TARGET_HAS_rot_i64
-    case INDEX_op_rotl_i64:
-    case INDEX_op_rotr_i64:
-#endif
-#ifdef TCG_TARGET_HAS_not_i64
-    case INDEX_op_not_i64:
-#endif
-#ifdef TCG_TARGET_HAS_ext8s_i64
-    case INDEX_op_ext8s_i64:
-#endif
-#ifdef TCG_TARGET_HAS_ext16s_i64
-    case INDEX_op_ext16s_i64:
-#endif
-#ifdef TCG_TARGET_HAS_ext32s_i64
-    case INDEX_op_ext32s_i64:
-#endif
-#ifdef TCG_TARGET_HAS_ext8u_i64
-    case INDEX_op_ext8u_i64:
-#endif
-#ifdef TCG_TARGET_HAS_ext16u_i64
-    case INDEX_op_ext16u_i64:
-#endif
-#ifdef TCG_TARGET_HAS_ext32u_i64
-    case INDEX_op_ext32u_i64:
-#endif
-        return 64;
-#endif
-    default:
-        fprintf(stderr, "Unrecognized operation %d in op_bits.\n", op);
-        tcg_abort();
-    }
+    const TCGOpDef *def = &tcg_op_defs[op];
+    return def->flags & TCG_OPF_64BIT ? 64 : 32;
 }
 
 static int op_to_movi(int op)
diff --git a/tcg/tcg-opc.h b/tcg/tcg-opc.h
index 2c7ca1a..b48669b 100644
--- a/tcg/tcg-opc.h
+++ b/tcg/tcg-opc.h
@@ -131,98 +131,98 @@ DEF(nor_i32, 1, 2, 0, 0)
 #endif
 
 #if TCG_TARGET_REG_BITS == 64
-DEF(mov_i64, 1, 1, 0, 0)
-DEF(movi_i64, 1, 0, 1, 0)
-DEF(setcond_i64, 1, 2, 1, 0)
+DEF(mov_i64, 1, 1, 0, TCG_OPF_64BIT)
+DEF(movi_i64, 1, 0, 1, TCG_OPF_64BIT)
+DEF(setcond_i64, 1, 2, 1, TCG_OPF_64BIT)
 /* load/store */
-DEF(ld8u_i64, 1, 1, 1, 0)
-DEF(ld8s_i64, 1, 1, 1, 0)
-DEF(ld16u_i64, 1, 1, 1, 0)
-DEF(ld16s_i64, 1, 1, 1, 0)
-DEF(ld32u_i64, 1, 1, 1, 0)
-DEF(ld32s_i64, 1, 1, 1, 0)
-DEF(ld_i64, 1, 1, 1, 0)
-DEF(st8_i64, 0, 2, 1, TCG_OPF_SIDE_EFFECTS)
-DEF(st16_i64, 0, 2, 1, TCG_OPF_SIDE_EFFECTS)
-DEF(st32_i64, 0, 2, 1, TCG_OPF_SIDE_EFFECTS)
-DEF(st_i64, 0, 2, 1, TCG_OPF_SIDE_EFFECTS)
+DEF(ld8u_i64, 1, 1, 1, TCG_OPF_64BIT)
+DEF(ld8s_i64, 1, 1, 1, TCG_OPF_64BIT)
+DEF(ld16u_i64, 1, 1, 1, TCG_OPF_64BIT)
+DEF(ld16s_i64, 1, 1, 1, TCG_OPF_64BIT)
+DEF(ld32u_i64, 1, 1, 1, TCG_OPF_64BIT)
+DEF(ld32s_i64, 1, 1, 1, TCG_OPF_64BIT)
+DEF(ld_i64, 1, 1, 1, TCG_OPF_64BIT)
+DEF(st8_i64, 0, 2, 1, TCG_OPF_SIDE_EFFECTS | TCG_OPF_64BIT)
+DEF(st16_i64, 0, 2, 1, TCG_OPF_SIDE_EFFECTS | TCG_OPF_64BIT)
+DEF(st32_i64, 0, 2, 1, TCG_OPF_SIDE_EFFECTS | TCG_OPF_64BIT)
+DEF(st_i64, 0, 2, 1, TCG_OPF_SIDE_EFFECTS | TCG_OPF_64BIT)
 /* arith */
-DEF(add_i64, 1, 2, 0, 0)
-DEF(sub_i64, 1, 2, 0, 0)
-DEF(mul_i64, 1, 2, 0, 0)
+DEF(add_i64, 1, 2, 0, TCG_OPF_64BIT)
+DEF(sub_i64, 1, 2, 0, TCG_OPF_64BIT)
+DEF(mul_i64, 1, 2, 0, TCG_OPF_64BIT)
 #ifdef TCG_TARGET_HAS_div_i64
-DEF(div_i64, 1, 2, 0, 0)
-DEF(divu_i64, 1, 2, 0, 0)
-DEF(rem_i64, 1, 2, 0, 0)
-DEF(remu_i64, 1, 2, 0, 0)
+DEF(div_i64, 1, 2, 0, TCG_OPF_64BIT)
+DEF(divu_i64, 1, 2, 0, TCG_OPF_64BIT)
+DEF(rem_i64, 1, 2, 0, TCG_OPF_64BIT)
+DEF(remu_i64, 1, 2, 0, TCG_OPF_64BIT)
 #endif
 #ifdef TCG_TARGET_HAS_div2_i64
-DEF(div2_i64, 2, 3, 0, 0)
-DEF(divu2_i64, 2, 3, 0, 0)
+DEF(div2_i64, 2, 3, 0, TCG_OPF_64BIT)
+DEF(divu2_i64, 2, 3, 0, TCG_OPF_64BIT)
 #endif
-DEF(and_i64, 1, 2, 0, 0)
-DEF(or_i64, 1, 2, 0, 0)
-DEF(xor_i64, 1, 2, 0, 0)
+DEF(and_i64, 1, 2, 0, TCG_OPF_64BIT)
+DEF(or_i64, 1, 2, 0, TCG_OPF_64BIT)
+DEF(xor_i64, 1, 2, 0, TCG_OPF_64BIT)
 /* shifts/rotates */
-DEF(shl_i64, 1, 2, 0, 0)
-DEF(shr_i64, 1, 2, 0, 0)
-DEF(sar_i64, 1, 2, 0, 0)
+DEF(shl_i64, 1, 2, 0, TCG_OPF_64BIT)
+DEF(shr_i64, 1, 2, 0, TCG_OPF_64BIT)
+DEF(sar_i64, 1, 2, 0, TCG_OPF_64BIT)
 #ifdef TCG_TARGET_HAS_rot_i64
-DEF(rotl_i64, 1, 2, 0, 0)
-DEF(rotr_i64, 1, 2, 0, 0)
+DEF(rotl_i64, 1, 2, 0, TCG_OPF_64BIT)
+DEF(rotr_i64, 1, 2, 0, TCG_OPF_64BIT)
 #endif
 #ifdef TCG_TARGET_HAS_deposit_i64
-DEF(deposit_i64, 1, 2, 2, 0)
+DEF(deposit_i64, 1, 2, 2, TCG_OPF_64BIT)
 #endif
 
-DEF(brcond_i64, 0, 2, 2, TCG_OPF_BB_END | TCG_OPF_SIDE_EFFECTS)
+DEF(brcond_i64, 0, 2, 2, TCG_OPF_BB_END | TCG_OPF_SIDE_EFFECTS | TCG_OPF_64BIT)
 #ifdef TCG_TARGET_HAS_ext8s_i64
-DEF(ext8s_i64, 1, 1, 0, 0)
+DEF(ext8s_i64, 1, 1, 0, TCG_OPF_64BIT)
 #endif
 #ifdef TCG_TARGET_HAS_ext16s_i64
-DEF(ext16s_i64, 1, 1, 0, 0)
+DEF(ext16s_i64, 1, 1, 0, TCG_OPF_64BIT)
 #endif
 #ifdef TCG_TARGET_HAS_ext32s_i64
-DEF(ext32s_i64, 1, 1, 0, 0)
+DEF(ext32s_i64, 1, 1, 0, TCG_OPF_64BIT)
 #endif
 #ifdef TCG_TARGET_HAS_ext8u_i64
-DEF(ext8u_i64, 1, 1, 0, 0)
+DEF(ext8u_i64, 1, 1, 0, TCG_OPF_64BIT)
 #endif
 #ifdef TCG_TARGET_HAS_ext16u_i64
-DEF(ext16u_i64, 1, 1, 0, 0)
+DEF(ext16u_i64, 1, 1, 0, TCG_OPF_64BIT)
 #endif
 #ifdef TCG_TARGET_HAS_ext32u_i64
-DEF(ext32u_i64, 1, 1, 0, 0)
+DEF(ext32u_i64, 1, 1, 0, TCG_OPF_64BIT)
 #endif
 #ifdef TCG_TARGET_HAS_bswap16_i64
-DEF(bswap16_i64, 1, 1, 0, 0)
+DEF(bswap16_i64, 1, 1, 0, TCG_OPF_64BIT)
 #endif
 #ifdef TCG_TARGET_HAS_bswap32_i64
-DEF(bswap32_i64, 1, 1, 0, 0)
+DEF(bswap32_i64, 1, 1, 0, TCG_OPF_64BIT)
 #endif
 #ifdef TCG_TARGET_HAS_bswap64_i64
-DEF(bswap64_i64, 1, 1, 0, 0)
+DEF(bswap64_i64, 1, 1, 0, TCG_OPF_64BIT)
 #endif
 #ifdef TCG_TARGET_HAS_not_i64
-DEF(not_i64, 1, 1, 0, 0)
+DEF(not_i64, 1, 1, 0, TCG_OPF_64BIT)
 #endif
 #ifdef TCG_TARGET_HAS_neg_i64
-DEF(neg_i64, 1, 1, 0, 0)
+DEF(neg_i64, 1, 1, 0, TCG_OPF_64BIT)
 #endif
 #ifdef TCG_TARGET_HAS_andc_i64
-DEF(andc_i64, 1, 2, 0, 0)
+DEF(andc_i64, 1, 2, 0, TCG_OPF_64BIT)
 #endif
 #ifdef TCG_TARGET_HAS_orc_i64
-DEF(orc_i64, 1, 2, 0, 0)
+DEF(orc_i64, 1, 2, 0, TCG_OPF_64BIT)
 #endif
 #ifdef TCG_TARGET_HAS_eqv_i64
-DEF(eqv_i64, 1, 2, 0, 0)
+DEF(eqv_i64, 1, 2, 0, TCG_OPF_64BIT)
 #endif
 #ifdef TCG_TARGET_HAS_nand_i64
-DEF(nand_i64, 1, 2, 0, 0)
+DEF(nand_i64, 1, 2, 0, TCG_OPF_64BIT)
 #endif
 #ifdef TCG_TARGET_HAS_nor_i64
-DEF(nor_i64, 1, 2, 0, 0)
+DEF(nor_i64, 1, 2, 0, TCG_OPF_64BIT)
 #endif
 #endif
 
diff --git a/tcg/tcg.c b/tcg/tcg.c
index 92f1989..7179bd4 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -68,7 +68,7 @@ static void tcg_target_qemu_prologue(TCGContext *s);
 static void patch_reloc(uint8_t *code_ptr, int type, 
                         tcg_target_long value, tcg_target_long addend);
 
-static TCGOpDef tcg_op_defs[] = {
+TCGOpDef tcg_op_defs[] = {
 #define DEF(s, oargs, iargs, cargs, flags) { #s, oargs, iargs, cargs, iargs + oargs + cargs, flags },
 #include "tcg-opc.h"
 #undef DEF
diff --git a/tcg/tcg.h b/tcg/tcg.h
index e2a7095..6a4f6e4 100644
--- a/tcg/tcg.h
+++ b/tcg/tcg.h
@@ -445,13 +445,18 @@ typedef struct TCGArgConstraint {
 
 #define TCG_MAX_OP_ARGS 16
 
-#define TCG_OPF_BB_END     0x01 /* instruction defines the end of a basic
-                                   block */
-#define TCG_OPF_CALL_CLOBBER 0x02 /* instruction clobbers call registers 
-                                   and potentially update globals. */
-#define TCG_OPF_SIDE_EFFECTS 0x04 /* instruction has side effects : it
-                                     cannot be removed if its output
-                                     are not used */
+/* Bits for TCGOpDef->flags, 8 bits available.  */
+enum {
+    /* Instruction defines the end of a basic block.  */
+    TCG_OPF_BB_END       = 0x01,
+    /* Instruction clobbers call registers and potentially update globals.  */
+    TCG_OPF_CALL_CLOBBER = 0x02,
+    /* Instruction has side effects: it cannot be removed
+       if its outputs are not used.  */
+    TCG_OPF_SIDE_EFFECTS = 0x04,
+    /* Instruction operands are 64-bits (otherwise 32-bits).  */
+    TCG_OPF_64BIT        = 0x08,
+};
 
 typedef struct TCGOpDef {
     const char *name;
@@ -463,6 +468,8 @@ typedef struct TCGOpDef {
     int used;
 #endif
 } TCGOpDef;
+
+extern TCGOpDef tcg_op_defs[];
         
 typedef struct TCGTargetOpDef {
     TCGOpcode op;
