diff --git a/include/exec/memop.h b/include/exec/memop.h
index 529d07b02dd4..04264ffd6b57 100644
--- a/include/exec/memop.h
+++ b/include/exec/memop.h
@@ -19,11 +19,15 @@ typedef enum MemOp {
     MO_16    = 1,
     MO_32    = 2,
     MO_64    = 3,
-    MO_SIZE  = 3,   /* Mask for the above.  */
+    MO_128   = 4,
+    MO_256   = 5,
+    MO_512   = 6,
+    MO_1024  = 7,
+    MO_SIZE  = 0x07,   /* Mask for the above.  */
 
-    MO_SIGN  = 4,   /* Sign-extended, otherwise zero-extended.  */
+    MO_SIGN  = 0x08,   /* Sign-extended, otherwise zero-extended.  */
 
-    MO_BSWAP = 8,   /* Host reverse endian.  */
+    MO_BSWAP = 0x10,   /* Host reverse endian.  */
 #ifdef HOST_WORDS_BIGENDIAN
     MO_LE    = MO_BSWAP,
     MO_BE    = 0,
@@ -59,8 +63,8 @@ typedef enum MemOp {
      * - an alignment to a specified size, which may be more or less than
      *   the access size (MO_ALIGN_x where 'x' is a size in bytes);
      */
-    MO_ASHIFT = 4,
-    MO_AMASK = 7 << MO_ASHIFT,
+    MO_ASHIFT = 5,
+    MO_AMASK = 0x7 << MO_ASHIFT,
 #ifdef NEED_CPU_H
 #ifdef TARGET_ALIGNED_ONLY
     MO_ALIGN = 0,
diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index ab6b346e357c..717afd481cb6 100644
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -1045,7 +1045,7 @@ static void read_vec_element(DisasContext *s, TCGv_i64 tcg_dest, int srcidx,
                              int element, MemOp memop)
 {
     int vect_off = vec_reg_offset(s, srcidx, element, memop & MO_SIZE);
-    switch (memop) {
+    switch ((unsigned)memop) {
     case MO_8:
         tcg_gen_ld8u_i64(tcg_dest, cpu_env, vect_off);
         break;
diff --git a/target/s390x/tcg/translate_vx.c.inc b/target/s390x/tcg/translate_vx.c.inc
index 0afa46e4637b..28bf5a23b68b 100644
--- a/target/s390x/tcg/translate_vx.c.inc
+++ b/target/s390x/tcg/translate_vx.c.inc
@@ -67,7 +67,7 @@ static void read_vec_element_i64(TCGv_i64 dst, uint8_t reg, uint8_t enr,
 {
     const int offs = vec_reg_offset(reg, enr, memop & MO_SIZE);
 
-    switch (memop) {
+    switch ((unsigned)memop) {
     case ES_8:
         tcg_gen_ld8u_i64(dst, cpu_env, offs);
         break;
diff --git a/tcg/aarch64/tcg-target.c.inc b/tcg/aarch64/tcg-target.c.inc
index 5924977b42b2..6f43c048a568 100644
--- a/tcg/aarch64/tcg-target.c.inc
+++ b/tcg/aarch64/tcg-target.c.inc
@@ -1547,7 +1547,7 @@ static void tcg_out_cltz(TCGContext *s, TCGType ext, TCGReg d,
 /* helper signature: helper_ret_ld_mmu(CPUState *env, target_ulong addr,
  *                                     TCGMemOpIdx oi, uintptr_t ra)
  */
-static void * const qemu_ld_helpers[4] = {
+static void * const qemu_ld_helpers[MO_SIZE + 1] = {
     [MO_8]  = helper_ret_ldub_mmu,
 #ifdef HOST_WORDS_BIGENDIAN
     [MO_16] = helper_be_lduw_mmu,
@@ -1564,7 +1564,7 @@ static void * const qemu_ld_helpers[4] = {
  *                                     uintxx_t val, TCGMemOpIdx oi,
  *                                     uintptr_t ra)
  */
-static void * const qemu_st_helpers[4] = {
+static void * const qemu_st_helpers[MO_SIZE + 1] = {
     [MO_8]  = helper_ret_stb_mmu,
 #ifdef HOST_WORDS_BIGENDIAN
     [MO_16] = helper_be_stw_mmu,
diff --git a/tcg/arm/tcg-target.c.inc b/tcg/arm/tcg-target.c.inc
index d25e68b36bea..d71f4a2317fa 100644
--- a/tcg/arm/tcg-target.c.inc
+++ b/tcg/arm/tcg-target.c.inc
@@ -1437,7 +1437,7 @@ static void tcg_out_vldst(TCGContext *s, ARMInsn insn,
 /* helper signature: helper_ret_ld_mmu(CPUState *env, target_ulong addr,
  *                                     int mmu_idx, uintptr_t ra)
  */
-static void * const qemu_ld_helpers[8] = {
+static void * const qemu_ld_helpers[MO_SSIZE + 1] = {
     [MO_UB]   = helper_ret_ldub_mmu,
     [MO_SB]   = helper_ret_ldsb_mmu,
 #ifdef HOST_WORDS_BIGENDIAN
@@ -1458,7 +1458,7 @@ static void * const qemu_ld_helpers[8] = {
 /* helper signature: helper_ret_st_mmu(CPUState *env, target_ulong addr,
  *                                     uintxx_t val, int mmu_idx, uintptr_t ra)
  */
-static void * const qemu_st_helpers[4] = {
+static void * const qemu_st_helpers[MO_SIZE + 1] = {
     [MO_8]   = helper_ret_stb_mmu,
 #ifdef HOST_WORDS_BIGENDIAN
     [MO_16] = helper_be_stw_mmu,
diff --git a/tcg/i386/tcg-target.c.inc b/tcg/i386/tcg-target.c.inc
index 997510109d0f..4aabc626061d 100644
--- a/tcg/i386/tcg-target.c.inc
+++ b/tcg/i386/tcg-target.c.inc
@@ -1611,7 +1611,7 @@ static void tcg_out_nopn(TCGContext *s, int n)
 /* helper signature: helper_ret_ld_mmu(CPUState *env, target_ulong addr,
  *                                     int mmu_idx, uintptr_t ra)
  */
-static void * const qemu_ld_helpers[16] = {
+static void * const qemu_ld_helpers[(MO_SIZE | MO_BSWAP) + 1] = {
     [MO_UB]   = helper_ret_ldub_mmu,
     [MO_LEUW] = helper_le_lduw_mmu,
     [MO_LEUL] = helper_le_ldul_mmu,
@@ -1624,7 +1624,7 @@ static void * const qemu_ld_helpers[16] = {
 /* helper signature: helper_ret_st_mmu(CPUState *env, target_ulong addr,
  *                                     uintxx_t val, int mmu_idx, uintptr_t ra)
  */
-static void * const qemu_st_helpers[16] = {
+static void * const qemu_st_helpers[(MO_SIZE | MO_BSWAP) + 1] = {
     [MO_UB]   = helper_ret_stb_mmu,
     [MO_LEUW] = helper_le_stw_mmu,
     [MO_LEUL] = helper_le_stl_mmu,
diff --git a/tcg/mips/tcg-target.c.inc b/tcg/mips/tcg-target.c.inc
index 41ffa2839498..84aa775c0d60 100644
--- a/tcg/mips/tcg-target.c.inc
+++ b/tcg/mips/tcg-target.c.inc
@@ -1017,7 +1017,7 @@ static void tcg_out_call(TCGContext *s, const tcg_insn_unit *arg)
 #if defined(CONFIG_SOFTMMU)
 #include "../tcg-ldst.c.inc"
 
-static void * const qemu_ld_helpers[16] = {
+static void * const qemu_ld_helpers[(MO_SSIZE | MO_BSWAP) + 1] = {
     [MO_UB]   = helper_ret_ldub_mmu,
     [MO_SB]   = helper_ret_ldsb_mmu,
     [MO_LEUW] = helper_le_lduw_mmu,
@@ -1034,7 +1034,7 @@ static void * const qemu_ld_helpers[16] = {
 #endif
 };
 
-static void * const qemu_st_helpers[16] = {
+static void * const qemu_st_helpers[(MO_SIZE | MO_BSWAP) + 1] = {
     [MO_UB]   = helper_ret_stb_mmu,
     [MO_LEUW] = helper_le_stw_mmu,
     [MO_LEUL] = helper_le_stl_mmu,
diff --git a/tcg/ppc/tcg-target.c.inc b/tcg/ppc/tcg-target.c.inc
index 5e1fac914a7d..7e8dee2cc62a 100644
--- a/tcg/ppc/tcg-target.c.inc
+++ b/tcg/ppc/tcg-target.c.inc
@@ -1931,7 +1931,7 @@ static void tcg_out_call(TCGContext *s, const tcg_insn_unit *target)
 #endif
 }
 
-static const uint32_t qemu_ldx_opc[16] = {
+static const uint32_t qemu_ldx_opc[(MO_SSIZE + MO_BSWAP) + 1] = {
     [MO_UB] = LBZX,
     [MO_UW] = LHZX,
     [MO_UL] = LWZX,
@@ -1944,7 +1944,7 @@ static const uint32_t qemu_ldx_opc[16] = {
     [MO_BSWAP | MO_Q]  = LDBRX,
 };
 
-static const uint32_t qemu_stx_opc[16] = {
+static const uint32_t qemu_stx_opc[(MO_SIZE + MO_BSWAP) + 1] = {
     [MO_UB] = STBX,
     [MO_UW] = STHX,
     [MO_UL] = STWX,
@@ -1965,7 +1965,7 @@ static const uint32_t qemu_exts_opc[4] = {
 /* helper signature: helper_ld_mmu(CPUState *env, target_ulong addr,
  *                                 int mmu_idx, uintptr_t ra)
  */
-static void * const qemu_ld_helpers[16] = {
+static void * const qemu_ld_helpers[(MO_SIZE | MO_BSWAP) + 1] = {
     [MO_UB]   = helper_ret_ldub_mmu,
     [MO_LEUW] = helper_le_lduw_mmu,
     [MO_LEUL] = helper_le_ldul_mmu,
@@ -1978,7 +1978,7 @@ static void * const qemu_ld_helpers[16] = {
 /* helper signature: helper_st_mmu(CPUState *env, target_ulong addr,
  *                                 uintxx_t val, int mmu_idx, uintptr_t ra)
  */
-static void * const qemu_st_helpers[16] = {
+static void * const qemu_st_helpers[(MO_SIZE | MO_BSWAP) + 1] = {
     [MO_UB]   = helper_ret_stb_mmu,
     [MO_LEUW] = helper_le_stw_mmu,
     [MO_LEUL] = helper_le_stl_mmu,
diff --git a/tcg/riscv/tcg-target.c.inc b/tcg/riscv/tcg-target.c.inc
index dc8d8f1de233..da48f9a633eb 100644
--- a/tcg/riscv/tcg-target.c.inc
+++ b/tcg/riscv/tcg-target.c.inc
@@ -852,7 +852,7 @@ static void tcg_out_mb(TCGContext *s, TCGArg a0)
 /* helper signature: helper_ret_ld_mmu(CPUState *env, target_ulong addr,
  *                                     TCGMemOpIdx oi, uintptr_t ra)
  */
-static void * const qemu_ld_helpers[8] = {
+static void * const qemu_ld_helpers[MO_SSIZE + 1] = {
     [MO_UB] = helper_ret_ldub_mmu,
     [MO_SB] = helper_ret_ldsb_mmu,
 #ifdef HOST_WORDS_BIGENDIAN
@@ -878,7 +878,7 @@ static void * const qemu_ld_helpers[8] = {
  *                                     uintxx_t val, TCGMemOpIdx oi,
  *                                     uintptr_t ra)
  */
-static void * const qemu_st_helpers[4] = {
+static void * const qemu_st_helpers[MO_SIZE + 1] = {
     [MO_8]   = helper_ret_stb_mmu,
 #ifdef HOST_WORDS_BIGENDIAN
     [MO_16] = helper_be_stw_mmu,
diff --git a/tcg/s390/tcg-target.c.inc b/tcg/s390/tcg-target.c.inc
index b82cf19f09b0..67a2ba5ff3c9 100644
--- a/tcg/s390/tcg-target.c.inc
+++ b/tcg/s390/tcg-target.c.inc
@@ -350,7 +350,7 @@ static const uint8_t tcg_cond_to_ltr_cond[] = {
 };
 
 #ifdef CONFIG_SOFTMMU
-static void * const qemu_ld_helpers[16] = {
+static void * const qemu_ld_helpers[(MO_SSIZE | MO_BSWAP) + 1] = {
     [MO_UB]   = helper_ret_ldub_mmu,
     [MO_SB]   = helper_ret_ldsb_mmu,
     [MO_LEUW] = helper_le_lduw_mmu,
@@ -365,7 +365,7 @@ static void * const qemu_ld_helpers[16] = {
     [MO_BEQ]  = helper_be_ldq_mmu,
 };
 
-static void * const qemu_st_helpers[16] = {
+static void * const qemu_st_helpers[(MO_SIZE | MO_BSWAP) + 1] = {
     [MO_UB]   = helper_ret_stb_mmu,
     [MO_LEUW] = helper_le_stw_mmu,
     [MO_LEUL] = helper_le_stl_mmu,
diff --git a/tcg/sparc/tcg-target.c.inc b/tcg/sparc/tcg-target.c.inc
index 9720d76abdca..43248776a140 100644
--- a/tcg/sparc/tcg-target.c.inc
+++ b/tcg/sparc/tcg-target.c.inc
@@ -855,8 +855,8 @@ static void tcg_out_mb(TCGContext *s, TCGArg a0)
 }
 
 #ifdef CONFIG_SOFTMMU
-static const tcg_insn_unit *qemu_ld_trampoline[16];
-static const tcg_insn_unit *qemu_st_trampoline[16];
+static const tcg_insn_unit *qemu_ld_trampoline[(MO_SSIZE | MO_BSWAP) + 1];
+static const tcg_insn_unit *qemu_st_trampoline[(MO_SIZE | MO_BSWAP) + 1];
 
 static void emit_extend(TCGContext *s, TCGReg r, int op)
 {
@@ -883,7 +883,7 @@ static void emit_extend(TCGContext *s, TCGReg r, int op)
 
 static void build_trampolines(TCGContext *s)
 {
-    static void * const qemu_ld_helpers[16] = {
+    static void * const qemu_ld_helpers[] = {
         [MO_UB]   = helper_ret_ldub_mmu,
         [MO_SB]   = helper_ret_ldsb_mmu,
         [MO_LEUW] = helper_le_lduw_mmu,
@@ -895,7 +895,7 @@ static void build_trampolines(TCGContext *s)
         [MO_BEUL] = helper_be_ldul_mmu,
         [MO_BEQ]  = helper_be_ldq_mmu,
     };
-    static void * const qemu_st_helpers[16] = {
+    static void * const qemu_st_helpers[] = {
         [MO_UB]   = helper_ret_stb_mmu,
         [MO_LEUW] = helper_le_stw_mmu,
         [MO_LEUL] = helper_le_stl_mmu,
@@ -908,7 +908,7 @@ static void build_trampolines(TCGContext *s)
     int i;
     TCGReg ra;
 
-    for (i = 0; i < 16; ++i) {
+    for (i = 0; i < ARRAY_SIZE(qemu_ld_helpers); ++i) {
         if (qemu_ld_helpers[i] == NULL) {
             continue;
         }
@@ -936,7 +936,7 @@ static void build_trampolines(TCGContext *s)
         tcg_out_mov(s, TCG_TYPE_PTR, TCG_REG_O7, ra);
     }
 
-    for (i = 0; i < 16; ++i) {
+    for (i = 0; i < ARRAY_SIZE(qemu_st_helpers); ++i) {
         if (qemu_st_helpers[i] == NULL) {
             continue;
         }
@@ -1118,7 +1118,7 @@ static TCGReg tcg_out_tlb_load(TCGContext *s, TCGReg addr, int mem_index,
 }
 #endif /* CONFIG_SOFTMMU */
 
-static const int qemu_ld_opc[16] = {
+static const int qemu_ld_opc[(MO_SSIZE | MO_BSWAP) + 1] = {
     [MO_UB]   = LDUB,
     [MO_SB]   = LDSB,
 
@@ -1135,7 +1135,7 @@ static const int qemu_ld_opc[16] = {
     [MO_LEQ]  = LDX_LE,
 };
 
-static const int qemu_st_opc[16] = {
+static const int qemu_st_opc[(MO_SIZE | MO_BSWAP) + 1] = {
     [MO_UB]   = STB,
 
     [MO_BEUW] = STH,
diff --git a/tcg/tcg-op.c b/tcg/tcg-op.c
index c7543965758c..e01f68f44d9d 100644
--- a/tcg/tcg-op.c
+++ b/tcg/tcg-op.c
@@ -2780,10 +2780,13 @@ static inline MemOp tcg_canonicalize_memop(MemOp op, bool is64, bool st)
         }
         break;
     case MO_64:
-        if (!is64) {
-            tcg_abort();
+        if (is64) {
+            op &= ~MO_SIGN;
+            break;
         }
-        break;
+        /* fall through */
+    default:
+        g_assert_not_reached();
     }
     if (st) {
         op &= ~MO_SIGN;
@@ -3095,7 +3098,7 @@ typedef void (*gen_atomic_op_i64)(TCGv_i64, TCGv_env, TCGv,
 # define WITH_ATOMIC64(X)
 #endif
 
-static void * const table_cmpxchg[16] = {
+static void * const table_cmpxchg[(MO_SIZE | MO_BSWAP) + 1] = {
     [MO_8] = gen_helper_atomic_cmpxchgb,
     [MO_16 | MO_LE] = gen_helper_atomic_cmpxchgw_le,
     [MO_16 | MO_BE] = gen_helper_atomic_cmpxchgw_be,
@@ -3297,7 +3300,7 @@ static void do_atomic_op_i64(TCGv_i64 ret, TCGv addr, TCGv_i64 val,
 }
 
 #define GEN_ATOMIC_HELPER(NAME, OP, NEW)                                \
-static void * const table_##NAME[16] = {                                \
+static void * const table_##NAME[(MO_SIZE | MO_BSWAP) + 1] = {          \
     [MO_8] = gen_helper_atomic_##NAME##b,                               \
     [MO_16 | MO_LE] = gen_helper_atomic_##NAME##w_le,                   \
     [MO_16 | MO_BE] = gen_helper_atomic_##NAME##w_be,                   \