diff --git a/src/backend_x64/emit_x64.cpp b/src/backend_x64/emit_x64.cpp
index 0dadd6c5..b20146f1 100644
--- a/src/backend_x64/emit_x64.cpp
+++ b/src/backend_x64/emit_x64.cpp
@@ -44,7 +44,7 @@ EmitContext::EmitContext(RegAlloc& reg_alloc, IR::Block& block)
 
 void EmitContext::EraseInstruction(IR::Inst* inst) {
     block.Instructions().erase(inst);
-    inst->Invalidate();
+    inst->ClearArgs();
 }
 
 template <typename JST>
@@ -187,10 +187,10 @@ void EmitX64<JST>::EmitMostSignificantWord(EmitContext& ctx, IR::Inst* inst) {
     code->shr(result, 32);
 
     if (carry_inst) {
-        ctx.EraseInstruction(carry_inst);
         Xbyak::Reg64 carry = ctx.reg_alloc.ScratchGpr();
         code->setc(carry.cvt8());
         ctx.reg_alloc.DefineValue(carry_inst, carry);
+        ctx.EraseInstruction(carry_inst);
     }
 
     ctx.reg_alloc.DefineValue(inst, result);
@@ -370,8 +370,6 @@ void EmitX64<JST>::EmitLogicalShiftLeft32(EmitContext& ctx, IR::Inst* inst) {
             ctx.reg_alloc.DefineValue(inst, result);
         }
     } else {
-        ctx.EraseInstruction(carry_inst);
-
         if (shift_arg.IsImmediate()) {
             u8 shift = shift_arg.GetImmediateU8();
             Xbyak::Reg32 result = ctx.reg_alloc.UseScratchGpr(operand_arg).cvt32();
@@ -392,8 +390,9 @@ void EmitX64<JST>::EmitLogicalShiftLeft32(EmitContext& ctx, IR::Inst* inst) {
                 code->and_(carry, 1);
             }
 
-            ctx.reg_alloc.DefineValue(inst, result);
             ctx.reg_alloc.DefineValue(carry_inst, carry);
+            ctx.EraseInstruction(carry_inst);
+            ctx.reg_alloc.DefineValue(inst, result);
         } else {
             ctx.reg_alloc.Use(shift_arg, HostLoc::RCX);
             Xbyak::Reg32 result = ctx.reg_alloc.UseScratchGpr(operand_arg).cvt32();
@@ -426,8 +425,9 @@ void EmitX64<JST>::EmitLogicalShiftLeft32(EmitContext& ctx, IR::Inst* inst) {
 
             code->outLocalLabel();
 
-            ctx.reg_alloc.DefineValue(inst, result);
             ctx.reg_alloc.DefineValue(carry_inst, carry);
+            ctx.EraseInstruction(carry_inst);
+            ctx.reg_alloc.DefineValue(inst, result);
         }
     }
 }
@@ -503,8 +503,6 @@ void EmitX64<JST>::EmitLogicalShiftRight32(EmitContext& ctx, IR::Inst* inst) {
             ctx.reg_alloc.DefineValue(inst, result);
         }
     } else {
-        ctx.EraseInstruction(carry_inst);
-
         if (shift_arg.IsImmediate()) {
             u8 shift = shift_arg.GetImmediateU8();
             Xbyak::Reg32 result = ctx.reg_alloc.UseScratchGpr(operand_arg).cvt32();
@@ -524,8 +522,9 @@ void EmitX64<JST>::EmitLogicalShiftRight32(EmitContext& ctx, IR::Inst* inst) {
                 code->xor_(carry, carry);
             }
 
-            ctx.reg_alloc.DefineValue(inst, result);
             ctx.reg_alloc.DefineValue(carry_inst, carry);
+            ctx.EraseInstruction(carry_inst);
+            ctx.reg_alloc.DefineValue(inst, result);
         } else {
             ctx.reg_alloc.Use(shift_arg, HostLoc::RCX);
             Xbyak::Reg32 result = ctx.reg_alloc.UseScratchGpr(operand_arg).cvt32();
@@ -560,8 +559,9 @@ void EmitX64<JST>::EmitLogicalShiftRight32(EmitContext& ctx, IR::Inst* inst) {
 
             code->outLocalLabel();
 
-            ctx.reg_alloc.DefineValue(inst, result);
             ctx.reg_alloc.DefineValue(carry_inst, carry);
+            ctx.EraseInstruction(carry_inst);
+            ctx.reg_alloc.DefineValue(inst, result);
         }
     }
 }
@@ -635,8 +635,6 @@ void EmitX64<JST>::EmitArithmeticShiftRight32(EmitContext& ctx, IR::Inst* inst)
             ctx.reg_alloc.DefineValue(inst, result);
         }
     } else {
-        ctx.EraseInstruction(carry_inst);
-
         if (shift_arg.IsImmediate()) {
             u8 shift = shift_arg.GetImmediateU8();
             Xbyak::Reg32 result = ctx.reg_alloc.UseScratchGpr(operand_arg).cvt32();
@@ -653,8 +651,9 @@ void EmitX64<JST>::EmitArithmeticShiftRight32(EmitContext& ctx, IR::Inst* inst)
                 code->setc(carry);
             }
 
-            ctx.reg_alloc.DefineValue(inst, result);
             ctx.reg_alloc.DefineValue(carry_inst, carry);
+            ctx.EraseInstruction(carry_inst);
+            ctx.reg_alloc.DefineValue(inst, result);
         } else {
             ctx.reg_alloc.Use(shift_arg, HostLoc::RCX);
             Xbyak::Reg32 result = ctx.reg_alloc.UseScratchGpr(operand_arg).cvt32();
@@ -683,8 +682,9 @@ void EmitX64<JST>::EmitArithmeticShiftRight32(EmitContext& ctx, IR::Inst* inst)
 
             code->outLocalLabel();
 
-            ctx.reg_alloc.DefineValue(inst, result);
             ctx.reg_alloc.DefineValue(carry_inst, carry);
+            ctx.EraseInstruction(carry_inst);
+            ctx.reg_alloc.DefineValue(inst, result);
         }
     }
 }
@@ -748,8 +748,6 @@ void EmitX64<JST>::EmitRotateRight32(EmitContext& ctx, IR::Inst* inst) {
             ctx.reg_alloc.DefineValue(inst, result);
         }
     } else {
-        ctx.EraseInstruction(carry_inst);
-
         if (shift_arg.IsImmediate()) {
             u8 shift = shift_arg.GetImmediateU8();
             Xbyak::Reg32 result = ctx.reg_alloc.UseScratchGpr(operand_arg).cvt32();
@@ -765,8 +763,9 @@ void EmitX64<JST>::EmitRotateRight32(EmitContext& ctx, IR::Inst* inst) {
                 code->setc(carry);
             }
 
-            ctx.reg_alloc.DefineValue(inst, result);
             ctx.reg_alloc.DefineValue(carry_inst, carry);
+            ctx.EraseInstruction(carry_inst);
+            ctx.reg_alloc.DefineValue(inst, result);
         } else {
             ctx.reg_alloc.UseScratch(shift_arg, HostLoc::RCX);
             Xbyak::Reg32 result = ctx.reg_alloc.UseScratchGpr(operand_arg).cvt32();
@@ -795,8 +794,9 @@ void EmitX64<JST>::EmitRotateRight32(EmitContext& ctx, IR::Inst* inst) {
 
             code->outLocalLabel();
 
-            ctx.reg_alloc.DefineValue(inst, result);
             ctx.reg_alloc.DefineValue(carry_inst, carry);
+            ctx.EraseInstruction(carry_inst);
+            ctx.reg_alloc.DefineValue(inst, result);
         }
     }
 }
@@ -838,11 +838,10 @@ void EmitX64<JST>::EmitRotateRightExtended(EmitContext& ctx, IR::Inst* inst) {
     code->rcr(result, 1);
 
     if (carry_inst) {
-        ctx.EraseInstruction(carry_inst);
-
         code->setc(carry);
 
         ctx.reg_alloc.DefineValue(carry_inst, carry);
+        ctx.EraseInstruction(carry_inst);
     }
 
     ctx.reg_alloc.DefineValue(inst, result);
@@ -912,20 +911,20 @@ static void EmitAdd(BlockOfCode* code, EmitContext& ctx, IR::Inst* inst, int bit
     }
 
     if (nzcv_inst) {
-        ctx.EraseInstruction(nzcv_inst);
         code->lahf();
         code->seto(code->al);
         ctx.reg_alloc.DefineValue(nzcv_inst, nzcv);
+        ctx.EraseInstruction(nzcv_inst);
     }
     if (carry_inst) {
-        ctx.EraseInstruction(carry_inst);
         code->setc(carry);
         ctx.reg_alloc.DefineValue(carry_inst, carry);
+        ctx.EraseInstruction(carry_inst);
     }
     if (overflow_inst) {
-        ctx.EraseInstruction(overflow_inst);
         code->seto(overflow);
         ctx.reg_alloc.DefineValue(overflow_inst, overflow);
+        ctx.EraseInstruction(overflow_inst);
     }
 
     ctx.reg_alloc.DefineValue(inst, result);
@@ -990,21 +989,21 @@ static void EmitSub(BlockOfCode* code, EmitContext& ctx, IR::Inst* inst, int bit
     }
 
     if (nzcv_inst) {
-        ctx.EraseInstruction(nzcv_inst);
         code->cmc();
         code->lahf();
         code->seto(code->al);
         ctx.reg_alloc.DefineValue(nzcv_inst, nzcv);
+        ctx.EraseInstruction(nzcv_inst);
     }
     if (carry_inst) {
-        ctx.EraseInstruction(carry_inst);
         code->setnc(carry);
         ctx.reg_alloc.DefineValue(carry_inst, carry);
+        ctx.EraseInstruction(carry_inst);
     }
     if (overflow_inst) {
-        ctx.EraseInstruction(overflow_inst);
         code->seto(overflow);
         ctx.reg_alloc.DefineValue(overflow_inst, overflow);
+        ctx.EraseInstruction(overflow_inst);
     }
 
     ctx.reg_alloc.DefineValue(inst, result);
@@ -1345,11 +1344,10 @@ void EmitX64<JST>::EmitSignedSaturatedAdd(EmitContext& ctx, IR::Inst* inst) {
     code->cmovo(result, overflow);
 
     if (overflow_inst) {
-        ctx.EraseInstruction(overflow_inst);
-
         code->seto(overflow.cvt8());
 
         ctx.reg_alloc.DefineValue(overflow_inst, overflow);
+        ctx.EraseInstruction(overflow_inst);
     }
 
     ctx.reg_alloc.DefineValue(inst, result);
@@ -1373,11 +1371,10 @@ void EmitX64<JST>::EmitSignedSaturatedSub(EmitContext& ctx, IR::Inst* inst) {
     code->cmovo(result, overflow);
 
     if (overflow_inst) {
-        ctx.EraseInstruction(overflow_inst);
-
         code->seto(overflow.cvt8());
 
         ctx.reg_alloc.DefineValue(overflow_inst, overflow);
+        ctx.EraseInstruction(overflow_inst);
     }
 
     ctx.reg_alloc.DefineValue(inst, result);
@@ -1405,11 +1402,10 @@ void EmitX64<JST>::EmitUnsignedSaturation(EmitContext& ctx, IR::Inst* inst) {
     code->cmovbe(result, reg_a);
 
     if (overflow_inst) {
-        ctx.EraseInstruction(overflow_inst);
-
         code->seta(overflow.cvt8());
 
         ctx.reg_alloc.DefineValue(overflow_inst, overflow);
+        ctx.EraseInstruction(overflow_inst);
     }
 
     ctx.reg_alloc.DefineValue(inst, result);
@@ -1456,11 +1452,10 @@ void EmitX64<JST>::EmitSignedSaturation(EmitContext& ctx, IR::Inst* inst) {
     code->cmovbe(result, reg_a);
 
     if (overflow_inst) {
-        ctx.EraseInstruction(overflow_inst);
-
         code->seta(overflow.cvt8());
 
         ctx.reg_alloc.DefineValue(overflow_inst, overflow);
+        ctx.EraseInstruction(overflow_inst);
     }
 
     ctx.reg_alloc.DefineValue(inst, result);
@@ -1477,8 +1472,6 @@ void EmitX64<JST>::EmitPackedAddU8(EmitContext& ctx, IR::Inst* inst) {
     code->paddb(xmm_a, xmm_b);
 
     if (ge_inst) {
-        ctx.EraseInstruction(ge_inst);
-
         Xbyak::Xmm xmm_ge = ctx.reg_alloc.ScratchXmm();
         Xbyak::Xmm ones = ctx.reg_alloc.ScratchXmm();
 
@@ -1490,6 +1483,7 @@ void EmitX64<JST>::EmitPackedAddU8(EmitContext& ctx, IR::Inst* inst) {
         code->pxor(xmm_ge, ones);
 
         ctx.reg_alloc.DefineValue(ge_inst, xmm_ge);
+        ctx.EraseInstruction(ge_inst);
     }
 
     ctx.reg_alloc.DefineValue(inst, xmm_a);
@@ -1504,8 +1498,6 @@ void EmitX64<JST>::EmitPackedAddS8(EmitContext& ctx, IR::Inst* inst) {
     Xbyak::Xmm xmm_b = ctx.reg_alloc.UseXmm(args[1]);
 
     if (ge_inst) {
-        ctx.EraseInstruction(ge_inst);
-
         Xbyak::Xmm saturated_sum = ctx.reg_alloc.ScratchXmm();
         Xbyak::Xmm xmm_ge = ctx.reg_alloc.ScratchXmm();
 
@@ -1517,6 +1509,7 @@ void EmitX64<JST>::EmitPackedAddS8(EmitContext& ctx, IR::Inst* inst) {
         code->pxor(xmm_ge, saturated_sum);
 
         ctx.reg_alloc.DefineValue(ge_inst, xmm_ge);
+        ctx.EraseInstruction(ge_inst);
     }
 
     code->paddb(xmm_a, xmm_b);
@@ -1535,8 +1528,6 @@ void EmitX64<JST>::EmitPackedAddU16(EmitContext& ctx, IR::Inst* inst) {
     code->paddw(xmm_a, xmm_b);
 
     if (ge_inst) {
-        ctx.EraseInstruction(ge_inst);
-
         if (code->DoesCpuSupport(Xbyak::util::Cpu::tSSE41)) {
             Xbyak::Xmm xmm_ge = ctx.reg_alloc.ScratchXmm();
             Xbyak::Xmm ones = ctx.reg_alloc.ScratchXmm();
@@ -1549,6 +1540,7 @@ void EmitX64<JST>::EmitPackedAddU16(EmitContext& ctx, IR::Inst* inst) {
             code->pxor(xmm_ge, ones);
 
             ctx.reg_alloc.DefineValue(ge_inst, xmm_ge);
+            ctx.EraseInstruction(ge_inst);
         } else {
             Xbyak::Xmm tmp_a = ctx.reg_alloc.ScratchXmm();
             Xbyak::Xmm tmp_b = ctx.reg_alloc.ScratchXmm();
@@ -1561,6 +1553,7 @@ void EmitX64<JST>::EmitPackedAddU16(EmitContext& ctx, IR::Inst* inst) {
             code->pcmpgtw(tmp_b, tmp_a); // *Signed* comparison!
 
             ctx.reg_alloc.DefineValue(ge_inst, tmp_b);
+            ctx.EraseInstruction(ge_inst);
         }
     }
 
@@ -1576,8 +1569,6 @@ void EmitX64<JST>::EmitPackedAddS16(EmitContext& ctx, IR::Inst* inst) {
     Xbyak::Xmm xmm_b = ctx.reg_alloc.UseXmm(args[1]);
 
     if (ge_inst) {
-        ctx.EraseInstruction(ge_inst);
-
         Xbyak::Xmm saturated_sum = ctx.reg_alloc.ScratchXmm();
         Xbyak::Xmm xmm_ge = ctx.reg_alloc.ScratchXmm();
 
@@ -1589,6 +1580,7 @@ void EmitX64<JST>::EmitPackedAddS16(EmitContext& ctx, IR::Inst* inst) {
         code->pxor(xmm_ge, saturated_sum);
 
         ctx.reg_alloc.DefineValue(ge_inst, xmm_ge);
+        ctx.EraseInstruction(ge_inst);
     }
 
     code->paddw(xmm_a, xmm_b);
@@ -1605,8 +1597,6 @@ void EmitX64<JST>::EmitPackedSubU8(EmitContext& ctx, IR::Inst* inst) {
     Xbyak::Xmm xmm_b = ctx.reg_alloc.UseXmm(args[1]);
 
     if (ge_inst) {
-        ctx.EraseInstruction(ge_inst);
-
         Xbyak::Xmm xmm_ge = ctx.reg_alloc.ScratchXmm();
 
         code->movdqa(xmm_ge, xmm_a);
@@ -1614,6 +1604,7 @@ void EmitX64<JST>::EmitPackedSubU8(EmitContext& ctx, IR::Inst* inst) {
         code->pcmpeqb(xmm_ge, xmm_a);
 
         ctx.reg_alloc.DefineValue(ge_inst, xmm_ge);
+        ctx.EraseInstruction(ge_inst);
     }
 
     code->psubb(xmm_a, xmm_b);
@@ -1630,8 +1621,6 @@ void EmitX64<JST>::EmitPackedSubS8(EmitContext& ctx, IR::Inst* inst) {
     Xbyak::Xmm xmm_b = ctx.reg_alloc.UseXmm(args[1]);
 
     if (ge_inst) {
-        ctx.EraseInstruction(ge_inst);
-
         Xbyak::Xmm saturated_sum = ctx.reg_alloc.ScratchXmm();
         Xbyak::Xmm xmm_ge = ctx.reg_alloc.ScratchXmm();
 
@@ -1643,6 +1632,7 @@ void EmitX64<JST>::EmitPackedSubS8(EmitContext& ctx, IR::Inst* inst) {
         code->pxor(xmm_ge, saturated_sum);
 
         ctx.reg_alloc.DefineValue(ge_inst, xmm_ge);
+        ctx.EraseInstruction(ge_inst);
     }
 
     code->psubb(xmm_a, xmm_b);
@@ -1659,8 +1649,6 @@ void EmitX64<JST>::EmitPackedSubU16(EmitContext& ctx, IR::Inst* inst) {
     Xbyak::Xmm xmm_b = ctx.reg_alloc.UseXmm(args[1]);
 
     if (ge_inst) {
-        ctx.EraseInstruction(ge_inst);
-
         if (code->DoesCpuSupport(Xbyak::util::Cpu::tSSE41)) {
             Xbyak::Xmm xmm_ge = ctx.reg_alloc.ScratchXmm();
 
@@ -1669,6 +1657,7 @@ void EmitX64<JST>::EmitPackedSubU16(EmitContext& ctx, IR::Inst* inst) {
             code->pcmpeqw(xmm_ge, xmm_a);
 
             ctx.reg_alloc.DefineValue(ge_inst, xmm_ge);
+            ctx.EraseInstruction(ge_inst);
         } else {
             Xbyak::Xmm xmm_ge = ctx.reg_alloc.ScratchXmm();
             Xbyak::Xmm ones = ctx.reg_alloc.ScratchXmm();
@@ -1682,6 +1671,7 @@ void EmitX64<JST>::EmitPackedSubU16(EmitContext& ctx, IR::Inst* inst) {
             code->pxor(xmm_ge, ones);
 
             ctx.reg_alloc.DefineValue(ge_inst, xmm_ge);
+            ctx.EraseInstruction(ge_inst);
         }
     }
 
@@ -1699,8 +1689,6 @@ void EmitX64<JST>::EmitPackedSubS16(EmitContext& ctx, IR::Inst* inst) {
     Xbyak::Xmm xmm_b = ctx.reg_alloc.UseXmm(args[1]);
 
     if (ge_inst) {
-        ctx.EraseInstruction(ge_inst);
-
         Xbyak::Xmm saturated_diff = ctx.reg_alloc.ScratchXmm();
         Xbyak::Xmm xmm_ge = ctx.reg_alloc.ScratchXmm();
 
@@ -1712,6 +1700,7 @@ void EmitX64<JST>::EmitPackedSubS16(EmitContext& ctx, IR::Inst* inst) {
         code->pxor(xmm_ge, saturated_diff);
 
         ctx.reg_alloc.DefineValue(ge_inst, xmm_ge);
+        ctx.EraseInstruction(ge_inst);
     }
 
     code->psubw(xmm_a, xmm_b);
@@ -2005,8 +1994,6 @@ void EmitPackedSubAdd(BlockOfCode* code, EmitContext& ctx, IR::Inst* inst, bool
     }
 
     if (ge_inst) {
-        ctx.EraseInstruction(ge_inst);
-
         // The reg_b registers are no longer required.
         Xbyak::Reg32 ge_sum = reg_b_hi;
         Xbyak::Reg32 ge_diff = reg_b_lo;
@@ -2028,6 +2015,7 @@ void EmitPackedSubAdd(BlockOfCode* code, EmitContext& ctx, IR::Inst* inst, bool
         code->or_(ge_sum, ge_diff);
 
         ctx.reg_alloc.DefineValue(ge_inst, ge_sum);
+        ctx.EraseInstruction(ge_inst);
     }
 
     if (is_halving) {
diff --git a/src/backend_x64/hostloc.h b/src/backend_x64/hostloc.h
index 7be3de3e..172e069a 100644
--- a/src/backend_x64/hostloc.h
+++ b/src/backend_x64/hostloc.h
@@ -48,6 +48,18 @@ inline bool HostLocIsSpill(HostLoc reg) {
     return reg >= HostLoc::FirstSpill;
 }
 
+inline size_t HostLocBitWidth(HostLoc loc) {
+    if (HostLocIsGPR(loc))
+        return 64;
+    if (HostLocIsXMM(loc))
+        return 128;
+    if (HostLocIsSpill(loc))
+        return 64;
+    if (HostLocIsFlag(loc))
+        return 1;
+    UNREACHABLE();
+}
+
 using HostLocList = std::initializer_list<HostLoc>;
 
 // RSP is preserved for function calls
diff --git a/src/backend_x64/reg_alloc.cpp b/src/backend_x64/reg_alloc.cpp
index e7ddf9e9..026bca92 100644
--- a/src/backend_x64/reg_alloc.cpp
+++ b/src/backend_x64/reg_alloc.cpp
@@ -39,6 +39,42 @@ static bool IsSameHostLocClass(HostLoc a, HostLoc b) {
            || (HostLocIsSpill(a) && HostLocIsSpill(b));
 }
 
+// Minimum number of bits required to represent a type
+static size_t GetBitWidth(IR::Type type) {
+    switch (type) {
+        case IR::Type::A32Reg:
+        case IR::Type::A32ExtReg:
+        case IR::Type::A64Reg:
+        case IR::Type::A64Vec:
+        case IR::Type::CoprocInfo:
+        case IR::Type::Cond:
+        case IR::Type::Void:
+            ASSERT_MSG(false, "Type %zu cannot be represented at runtime", static_cast<size_t>(type));
+            return 0;
+        case IR::Type::Opaque:
+            ASSERT_MSG(false, "Not a concrete type");
+            return 0;
+        case IR::Type::U1:
+            return 8;
+        case IR::Type::U8:
+            return 8;
+        case IR::Type::U16:
+            return 16;
+        case IR::Type::U32:
+            return 32;
+        case IR::Type::U64:
+            return 64;
+        case IR::Type::F32:
+            return 32;
+        case IR::Type::F64:
+            return 64;
+        case IR::Type::F128:
+            return 128;
+        case IR::Type::NZCVFlags:
+            return 32; // TODO: Update to 16 when flags optimization is done
+    }
+}
+
 bool HostLocInfo::IsLocked() const {
     return is_being_used;
 }
@@ -51,10 +87,6 @@ bool HostLocInfo::IsLastUse() const {
     return !is_being_used && current_references == 1 && accumulated_uses + 1 == total_uses;
 }
 
-bool HostLocInfo::ContainsValue(const IR::Inst* inst) const {
-    return std::find(values.begin(), values.end(), inst) != values.end();
-}
-
 void HostLocInfo::ReadLock() {
     ASSERT(!is_scratch);
     is_being_used = true;
@@ -66,11 +98,6 @@ void HostLocInfo::WriteLock() {
     is_scratch = true;
 }
 
-void HostLocInfo::AddValue(IR::Inst* inst) {
-    values.push_back(inst);
-    total_uses += inst->UseCount();
-}
-
 void HostLocInfo::AddArgReference() {
     current_references++;
     ASSERT(accumulated_uses + current_references <= total_uses);
@@ -84,6 +111,7 @@ void HostLocInfo::EndOfAllocScope() {
         values.clear();
         accumulated_uses = 0;
         total_uses = 0;
+        max_bit_width = 0;
     }
 
     ASSERT(total_uses == std::accumulate(values.begin(), values.end(), size_t(0), [](size_t sum, IR::Inst* inst) { return sum + inst->UseCount(); }));
@@ -92,6 +120,20 @@ void HostLocInfo::EndOfAllocScope() {
     is_scratch = false;
 }
 
+bool HostLocInfo::ContainsValue(const IR::Inst* inst) const {
+    return std::find(values.begin(), values.end(), inst) != values.end();
+}
+
+size_t HostLocInfo::GetMaxBitWidth() const {
+    return max_bit_width;
+}
+
+void HostLocInfo::AddValue(IR::Inst* inst) {
+    values.push_back(inst);
+    total_uses += inst->UseCount();
+    max_bit_width = std::max(max_bit_width, GetBitWidth(inst->GetType()));
+}
+
 IR::Type Argument::GetType() const {
     return value.GetType();
 }
@@ -439,15 +481,16 @@ HostLoc RegAlloc::LoadImmediate(IR::Value imm, HostLoc host_loc) {
 
 void RegAlloc::Move(HostLoc to, HostLoc from) {
     ASSERT(LocInfo(to).IsEmpty() && !LocInfo(from).IsLocked());
+    ASSERT(LocInfo(from).GetMaxBitWidth() <= HostLocBitWidth(to));
 
     if (LocInfo(from).IsEmpty()) {
         return;
     }
 
+    EmitMove(to, from);
+
     LocInfo(to) = LocInfo(from);
     LocInfo(from) = {};
-
-    EmitMove(to, from);
 }
 
 void RegAlloc::CopyToScratch(HostLoc to, HostLoc from) {
@@ -458,6 +501,8 @@ void RegAlloc::CopyToScratch(HostLoc to, HostLoc from) {
 
 void RegAlloc::Exchange(HostLoc a, HostLoc b) {
     ASSERT(!LocInfo(a).IsLocked() && !LocInfo(b).IsLocked());
+    ASSERT(LocInfo(a).GetMaxBitWidth() <= HostLocBitWidth(b));
+    ASSERT(LocInfo(b).GetMaxBitWidth() <= HostLocBitWidth(a));
 
     if (LocInfo(a).IsEmpty()) {
         Move(a, b);
@@ -469,9 +514,9 @@ void RegAlloc::Exchange(HostLoc a, HostLoc b) {
         return;
     }
 
-    std::swap(LocInfo(a), LocInfo(b));
-
     EmitExchange(a, b);
+
+    std::swap(LocInfo(a), LocInfo(b));
 }
 
 void RegAlloc::MoveOutOfTheWay(HostLoc reg) {
@@ -511,22 +556,81 @@ const HostLocInfo& RegAlloc::LocInfo(HostLoc loc) const {
 }
 
 void RegAlloc::EmitMove(HostLoc to, HostLoc from) {
+    const size_t bit_width = LocInfo(from).GetMaxBitWidth();
+
     if (HostLocIsXMM(to) && HostLocIsXMM(from)) {
         code->movaps(HostLocToXmm(to), HostLocToXmm(from));
     } else if (HostLocIsGPR(to) && HostLocIsGPR(from)) {
-        code->mov(HostLocToReg64(to), HostLocToReg64(from));
+        ASSERT(bit_width != 128);
+        if (bit_width == 64) {
+            code->mov(HostLocToReg64(to), HostLocToReg64(from));
+        } else {
+            code->mov(HostLocToReg64(to).cvt32(), HostLocToReg64(from).cvt32());
+        }
     } else if (HostLocIsXMM(to) && HostLocIsGPR(from)) {
-        code->movq(HostLocToXmm(to), HostLocToReg64(from));
+        ASSERT(bit_width != 128);
+        if (bit_width == 64) {
+            code->movq(HostLocToXmm(to), HostLocToReg64(from));
+        } else {
+            code->movd(HostLocToXmm(to), HostLocToReg64(from).cvt32());
+        }
     } else if (HostLocIsGPR(to) && HostLocIsXMM(from)) {
-        code->movq(HostLocToReg64(to), HostLocToXmm(from));
+        ASSERT(bit_width != 128);
+        if (bit_width == 64) {
+            code->movq(HostLocToReg64(to), HostLocToXmm(from));
+        } else {
+            code->movd(HostLocToReg64(to).cvt32(), HostLocToXmm(from));
+        }
     } else if (HostLocIsXMM(to) && HostLocIsSpill(from)) {
-        code->movsd(HostLocToXmm(to), spill_to_addr(from));
+        Xbyak::Address spill_addr = spill_to_addr(from);
+        ASSERT(spill_addr.getBit() >= bit_width);
+        switch (bit_width) {
+        case 128:
+            code->movaps(HostLocToXmm(to), spill_addr);
+            break;
+        case 64:
+            code->movsd(HostLocToXmm(to), spill_addr);
+            break;
+        case 32:
+        case 16:
+        case 8:
+            code->movss(HostLocToXmm(to), spill_addr);
+            break;
+        default:
+            UNREACHABLE();
+        }
     } else if (HostLocIsSpill(to) && HostLocIsXMM(from)) {
-        code->movsd(spill_to_addr(to), HostLocToXmm(from));
+        Xbyak::Address spill_addr = spill_to_addr(to);
+        ASSERT(spill_addr.getBit() >= bit_width);
+        switch (bit_width) {
+        case 128:
+            code->movaps(spill_addr, HostLocToXmm(from));
+            break;
+        case 64:
+            code->movsd(spill_addr, HostLocToXmm(from));
+            break;
+        case 32:
+        case 16:
+        case 8:
+            code->movss(spill_addr, HostLocToXmm(from));
+            break;
+        default:
+            UNREACHABLE();
+        }
     } else if (HostLocIsGPR(to) && HostLocIsSpill(from)) {
-        code->mov(HostLocToReg64(to), spill_to_addr(from));
+        ASSERT(bit_width != 128);
+        if (bit_width == 64) {
+            code->mov(HostLocToReg64(to), spill_to_addr(from));
+        } else {
+            code->mov(HostLocToReg64(to).cvt32(), spill_to_addr(from));
+        }
     } else if (HostLocIsSpill(to) && HostLocIsGPR(from)) {
-        code->mov(spill_to_addr(to), HostLocToReg64(from));
+        ASSERT(bit_width != 128);
+        if (bit_width == 64) {
+            code->mov(spill_to_addr(to), HostLocToReg64(from));
+        } else {
+            code->mov(spill_to_addr(to), HostLocToReg64(from).cvt32());
+        }
     } else {
         ASSERT_MSG(false, "Invalid RegAlloc::EmitMove");
     }
diff --git a/src/backend_x64/reg_alloc.h b/src/backend_x64/reg_alloc.h
index 0e9fff00..4032a361 100644
--- a/src/backend_x64/reg_alloc.h
+++ b/src/backend_x64/reg_alloc.h
@@ -32,24 +32,29 @@ public:
     bool IsEmpty() const;
     bool IsLastUse() const;
 
-    bool ContainsValue(const IR::Inst* inst) const;
-
     void ReadLock();
     void WriteLock();
-
-    void AddValue(IR::Inst* inst);
-
     void AddArgReference();
     void EndOfAllocScope();
 
+    bool ContainsValue(const IR::Inst* inst) const;
+    size_t GetMaxBitWidth() const;
+
+    void AddValue(IR::Inst* inst);
+
 private:
-    std::vector<IR::Inst*> values;
+    // Current instruction state
     bool is_being_used = false;
     bool is_scratch = false;
 
+    // Block state
     size_t current_references = 0;
     size_t accumulated_uses = 0;
     size_t total_uses = 0;
+
+    // Value state
+    std::vector<IR::Inst*> values;
+    size_t max_bit_width = 0;
 };
 
 struct Argument {
diff --git a/src/frontend/ir/microinstruction.cpp b/src/frontend/ir/microinstruction.cpp
index bd68255b..be477012 100644
--- a/src/frontend/ir/microinstruction.cpp
+++ b/src/frontend/ir/microinstruction.cpp
@@ -360,13 +360,17 @@ void Inst::SetArg(size_t index, Value value) {
 }
 
 void Inst::Invalidate() {
+    ClearArgs();
+    op = Opcode::Void;
+}
+
+void Inst::ClearArgs() {
     for (auto& value : args) {
         if (!value.IsImmediate()) {
             UndoUse(value);
         }
         value = {};
     }
-    op = Opcode::Void;
 }
 
 void Inst::ReplaceUsesWith(Value replacement) {
diff --git a/src/frontend/ir/microinstruction.h b/src/frontend/ir/microinstruction.h
index 04fd7bdf..1a9bbc1b 100644
--- a/src/frontend/ir/microinstruction.h
+++ b/src/frontend/ir/microinstruction.h
@@ -105,6 +105,7 @@ public:
     void SetArg(size_t index, Value value);
 
     void Invalidate();
+    void ClearArgs();
 
     void ReplaceUsesWith(Value replacement);