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// Copyright 2017 The Australian National University
// 
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// 
//     http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

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// TODO: CHECK THAT THE TYPE OF EVERY MEMORY LOCATION HAS THE CORRECT SIZE
// (the size should be size of the area in memory that it is referring to, and will indicate
// how much data any load/store instructions that uses it will operate on
// (so it should be [1], 8, 16, 32, 64, or 128 bits in size (when using emit_mem, it can have other sizes before this))


#![allow(non_upper_case_globals)]
// TODO: Move architecture independent codes in here, inst_sel and asm_backend to somewhere else...
pub mod inst_sel;

mod codegen;
pub use compiler::backend::aarch64::codegen::CodeGenerator;

mod asm_backend;
pub use compiler::backend::aarch64::asm_backend::ASMCodeGen;
pub use compiler::backend::aarch64::asm_backend::emit_code;
pub use compiler::backend::aarch64::asm_backend::emit_context;
pub use compiler::backend::aarch64::asm_backend::emit_context_with_reloc;
use utils::Address;

#[cfg(feature = "aot")]
pub use compiler::backend::aarch64::asm_backend::spill_rewrite;

use ast::ptr::P;
use ast::ir::*;
use ast::types::*;
use ast::op;
use compiler::backend::RegGroup;
use vm::VM;

use utils::LinkedHashMap;
use std::collections::HashMap;

// Number of nromal callee saved registers (excluding FP and LR, and SP)
pub const CALLEE_SAVED_COUNT : usize = 18;

macro_rules! REGISTER {
    ($id:expr, $name: expr, $ty: ident) => {
        {
            P(Value {
                hdr: MuEntityHeader::named($id, $name.to_string()),
                ty: $ty.clone(),
                v: Value_::SSAVar($id)
            })
        }
    };
}

macro_rules! GPR_ALIAS {
    ($alias: ident: ($id64: expr, $r64: ident) -> $r32: ident) => {
        lazy_static!{
            pub static ref $r64 : P<Value> = REGISTER!($id64,    stringify!($r64), UINT64_TYPE);
            pub static ref $r32 : P<Value> = REGISTER!($id64 +1, stringify!($r32), UINT32_TYPE);
            pub static ref $alias : [P<Value>; 2] = [$r64.clone(), $r32.clone()];
        }
    };
}

// Used to create a generic alias name
macro_rules! ALIAS {
    ($src: ident -> $dest: ident) => {
        //pub use $src as $dest;
        lazy_static!{
            pub static ref $dest : P<Value> = $src.clone();
        }
    };
}


macro_rules! FPR_ALIAS {
    ($alias: ident: ($id64: expr, $r64: ident) -> $r32: ident) => {
        lazy_static!{
            pub static ref $r64 : P<Value> = REGISTER!($id64,    stringify!($r64), DOUBLE_TYPE);
            pub static ref $r32 : P<Value> = REGISTER!($id64 +1, stringify!($r32), FLOAT_TYPE);
            pub static ref $alias : [P<Value>; 2] = [$r64.clone(), $r32.clone()];
        }
    };
}

GPR_ALIAS!(X0_ALIAS: (0, X0)  -> W0);
GPR_ALIAS!(X1_ALIAS: (2, X1)  -> W1);
GPR_ALIAS!(X2_ALIAS: (4, X2)  -> W2);
GPR_ALIAS!(X3_ALIAS: (6, X3)  -> W3);
GPR_ALIAS!(X4_ALIAS: (8, X4)  -> W4);
GPR_ALIAS!(X5_ALIAS: (10, X5)  -> W5);
GPR_ALIAS!(X6_ALIAS: (12, X6)  -> W6);
GPR_ALIAS!(X7_ALIAS: (14, X7)  -> W7);
GPR_ALIAS!(X8_ALIAS: (16, X8)  -> W8);
GPR_ALIAS!(X9_ALIAS: (18, X9)  -> W9);
GPR_ALIAS!(X10_ALIAS: (20, X10)  -> W10);
GPR_ALIAS!(X11_ALIAS: (22, X11)  -> W11);
GPR_ALIAS!(X12_ALIAS: (24, X12)  -> W12);
GPR_ALIAS!(X13_ALIAS: (26, X13)  -> W13);
GPR_ALIAS!(X14_ALIAS: (28, X14)  -> W14);
GPR_ALIAS!(X15_ALIAS: (30, X15)  -> W15);
GPR_ALIAS!(X16_ALIAS: (32, X16)  -> W16);
GPR_ALIAS!(X17_ALIAS: (34, X17)  -> W17);
GPR_ALIAS!(X18_ALIAS: (36, X18)  -> W18);
GPR_ALIAS!(X19_ALIAS: (38, X19)  -> W19);
GPR_ALIAS!(X20_ALIAS: (40, X20)  -> W20);
GPR_ALIAS!(X21_ALIAS: (42, X21)  -> W21);
GPR_ALIAS!(X22_ALIAS: (44, X22)  -> W22);
GPR_ALIAS!(X23_ALIAS: (46, X23)  -> W23);
GPR_ALIAS!(X24_ALIAS: (48, X24)  -> W24);
GPR_ALIAS!(X25_ALIAS: (50, X25)  -> W25);
GPR_ALIAS!(X26_ALIAS: (52, X26)  -> W26);
GPR_ALIAS!(X27_ALIAS: (54, X27)  -> W27);
GPR_ALIAS!(X28_ALIAS: (56, X28)  -> W28);
GPR_ALIAS!(X29_ALIAS: (58, X29)  -> W29);
GPR_ALIAS!(X30_ALIAS: (60, X30)  -> W30);
GPR_ALIAS!(SP_ALIAS: (62, SP)  -> WSP); // Special register (only some instructions can reference it)
GPR_ALIAS!(XZR_ALIAS: (64, XZR)  -> WZR); // Pseudo register, not to be used by register allocator

// Aliases
ALIAS!(X8 -> XR); // Indirect result location register (points to a location in memory to write return values to)
ALIAS!(X16 -> IP0); // Intra proecdure call register 0 (may be modified by the linker when executing BL/BLR instructions)
ALIAS!(X17 -> IP1);// Intra proecdure call register 1 (may be modified by the linker when executing BL/BLR instructions)
ALIAS!(X18 -> PR); // Platform Register (NEVER TOUCH THIS REGISTER (Unless you can prove Linux dosn't use it))
ALIAS!(X29 -> FP); // Frame Pointer (can be used as a normal register when not calling or returning)
ALIAS!(X30 -> LR); // Link Register (not supposed to be used for any other purpose)


lazy_static! {
    pub static ref GPR_ALIAS_TABLE : LinkedHashMap<MuID, Vec<P<Value>>> = {
        let mut ret = LinkedHashMap::new();

        ret.insert(X0.id(), X0_ALIAS.to_vec());
        ret.insert(X1.id(), X1_ALIAS.to_vec());
        ret.insert(X2.id(), X2_ALIAS.to_vec());
        ret.insert(X3.id(), X3_ALIAS.to_vec());
        ret.insert(X4.id(), X4_ALIAS.to_vec());
        ret.insert(X5.id(), X5_ALIAS.to_vec());
        ret.insert(X6.id(), X6_ALIAS.to_vec());
        ret.insert(X7.id(), X7_ALIAS.to_vec());
        ret.insert(X8.id(), X8_ALIAS.to_vec());
        ret.insert(X9.id(), X9_ALIAS.to_vec());
        ret.insert(X10.id(), X10_ALIAS.to_vec());
        ret.insert(X11.id(), X11_ALIAS.to_vec());
        ret.insert(X12.id(), X12_ALIAS.to_vec());
        ret.insert(X13.id(), X13_ALIAS.to_vec());
        ret.insert(X14.id(), X14_ALIAS.to_vec());
        ret.insert(X15.id(), X15_ALIAS.to_vec());
        ret.insert(X16.id(), X16_ALIAS.to_vec());
        ret.insert(X17.id(), X17_ALIAS.to_vec());
        ret.insert(X18.id(), X18_ALIAS.to_vec());
        ret.insert(X19.id(), X19_ALIAS.to_vec());
        ret.insert(X20.id(), X20_ALIAS.to_vec());
        ret.insert(X21.id(), X21_ALIAS.to_vec());
        ret.insert(X22.id(), X22_ALIAS.to_vec());
        ret.insert(X23.id(), X23_ALIAS.to_vec());
        ret.insert(X24.id(), X24_ALIAS.to_vec());
        ret.insert(X25.id(), X25_ALIAS.to_vec());
        ret.insert(X26.id(), X26_ALIAS.to_vec());
        ret.insert(X27.id(), X27_ALIAS.to_vec());
        ret.insert(X28.id(), X28_ALIAS.to_vec());
        ret.insert(X29.id(), X29_ALIAS.to_vec());
        ret.insert(X30.id(), X30_ALIAS.to_vec());
        ret.insert(SP.id(), SP_ALIAS.to_vec());
        ret.insert(XZR.id(), XZR_ALIAS.to_vec());
        ret
    };

    // e.g. given eax, return rax
    pub static ref GPR_ALIAS_LOOKUP : HashMap<MuID, P<Value>> = {
        let mut ret = HashMap::new();

        for vec in GPR_ALIAS_TABLE.values() {
            let colorable = vec[0].clone();

            for gpr in vec {
                ret.insert(gpr.id(), colorable.clone());
            }
        }

        ret
    };
}

// Is val a hard coded machine register (not a pseudo register)
pub fn is_machine_reg(val: &P<Value>) -> bool {
    match val.v {
        Value_::SSAVar(ref id) => {
            if *id < FPR_ID_START {
                match GPR_ALIAS_LOOKUP.get(&id) {
                    Some(_) => true,
                    None => false
                }
            } else {
                match FPR_ALIAS_LOOKUP.get(&id) {
                    Some(_) => true,
                    None => false
                }
            }
        }
        _ => false
    }

}


// Returns a P<Value> to the register id
pub fn get_register_from_id(id: MuID) -> P<Value> {
    if id < FPR_ID_START {
        match GPR_ALIAS_LOOKUP.get(&id) {
            Some(val) => val.clone(),
            None => panic!("cannot find GPR {}", id)
        }
    } else {
        match FPR_ALIAS_LOOKUP.get(&id) {
            Some(val) => val.clone(),
            None => panic!("cannot find FPR {}", id)
        }
    }
}

pub fn get_alias_for_length(id: MuID, length: usize) -> P<Value> {
    if id < FPR_ID_START {
        let vec = match GPR_ALIAS_TABLE.get(&id) {
            Some(vec) => vec,
            None => panic!("didnt find {} as GPR", id)
        };

        if length > 32 {
            vec[0].clone()
        } else {
            vec[1].clone()
        }
    } else {
        let vec = match FPR_ALIAS_TABLE.get(&id) {
            Some(vec) => vec,
            None => panic!("didnt find {} as FPR", id)
        };

        if length > 32 {
            vec[0].clone()
        } else {
            vec[1].clone()
        }
    }
}

pub fn is_aliased(id1: MuID, id2: MuID) -> bool {
    return get_color_for_precolored(id1) == get_color_for_precolored(id2);
}

pub fn get_color_for_precolored(id: MuID) -> MuID {
    debug_assert!(id < MACHINE_ID_END);

    if id < FPR_ID_START {
        match GPR_ALIAS_LOOKUP.get(&id) {
            Some(val) => val.id(),
            None => panic!("cannot find GPR {}", id)
        }
    } else {
        match FPR_ALIAS_LOOKUP.get(&id) {
            Some(val) => val.id(),
            None => panic!("cannot find FPR {}", id)
        }
    }
}

#[inline(always)]
pub fn check_op_len(ty: &P<MuType>) -> usize {
    match ty.get_int_length() {
        Some(64) => 64,
        Some(32) => 32,
        Some(n) if n < 32 => 32,
        Some(n) => panic!("unimplemented int size: {}", n),
        None => {
            match ty.v {
                MuType_::Float => 32,
                MuType_::Double => 64,
                _ => panic!("unimplemented primitive type: {}", ty)
            }
        }
    }
}

#[inline(always)]
pub fn get_bit_size(ty : &P<MuType>, vm: &VM) -> usize
{
    match ty.get_int_length() {
        Some(val) => val,
        None => {
            match ty.v {
                MuType_::Float => 32,
                MuType_::Double => 64,
                MuType_::Vector(ref t, n) => get_bit_size(t, vm)*n,
                MuType_::Array(ref t, n) => get_bit_size(t, vm)*n,
                MuType_::Void => 0,
                _ => vm.get_type_size(ty.id())*8,
            }
        }
    }
}

#[inline(always)]
pub fn get_type_alignment(ty: &P<MuType>, vm: &VM) -> usize
{
    vm.get_backend_type_info(ty.id()).alignment
}

#[inline(always)]
pub fn primitive_byte_size(ty : &P<MuType>) -> usize
{
    match ty.get_int_length() {
        Some(val) => round_up(val, 8)/8,
        None => {
            match ty.v {
                MuType_::Float => 4,
                MuType_::Double => 8,
                MuType_::Void => 0,
                _ => panic!("Not a primitive type")
            }
        }
    }
}

lazy_static! {
    // Note: these are the same as the ARGUMENT_GPRs
    pub static ref RETURN_GPRs : [P<Value>; 8] = [
        X0.clone(),
        X1.clone(),
        X2.clone(),
        X3.clone(),
        X4.clone(),
        X5.clone(),
        X6.clone(),
        X7.clone()
    ];

    pub static ref ARGUMENT_GPRs : [P<Value>; 8] = [
        X0.clone(),
        X1.clone(),
        X2.clone(),
        X3.clone(),
        X4.clone(),
        X5.clone(),
        X6.clone(),
        X7.clone()
    ];

    pub static ref CALLEE_SAVED_GPRs : [P<Value>; 10] = [
        X19.clone(),
        X20.clone(),
        X21.clone(),
        X22.clone(),
        X23.clone(),
        X24.clone(),
        X25.clone(),
        X26.clone(),
        X27.clone(),
        X28.clone(),

        // Note: These two are technically CALLEE saved but need to be dealt with specially
        //X29.clone(), // Frame Pointer
        //X30.clone() // Link Register
    ];

    pub static ref CALLER_SAVED_GPRs : [P<Value>; 18] = [
        X0.clone(),
        X1.clone(),
        X2.clone(),
        X3.clone(),
        X4.clone(),
        X5.clone(),
        X6.clone(),
        X7.clone(),
        X8.clone(),
        X9.clone(),
        X10.clone(),
        X11.clone(),
        X12.clone(),
        X13.clone(),
        X14.clone(),
        X15.clone(),
        X16.clone(),
        X17.clone(),
        //X18.clone(), // Platform Register
    ];

    static ref ALL_GPRs : [P<Value>; 30] = [
        X0.clone(),
        X1.clone(),
        X2.clone(),
        X3.clone(),
        X4.clone(),
        X5.clone(),
        X6.clone(),
        X7.clone(),
        X8.clone(),
        X9.clone(),
        X10.clone(),
        X11.clone(),
        X12.clone(),
        X13.clone(),
        X14.clone(),
        X15.clone(),
        X16.clone(),
        X17.clone(),
        //X18.clone(), // Platform Register
        X19.clone(),
        X20.clone(),
        X21.clone(),
        X22.clone(),
        X23.clone(),
        X24.clone(),
        X25.clone(),
        X26.clone(),
        X27.clone(),
        X28.clone(),
        X29.clone(), // Frame Pointer
        X30.clone() // Link Register
    ];
}

pub const FPR_ID_START : usize = 100;

FPR_ALIAS!(D0_ALIAS: (FPR_ID_START + 0, D0)  -> S0);
FPR_ALIAS!(D1_ALIAS: (FPR_ID_START + 2, D1)  -> S1);
FPR_ALIAS!(D2_ALIAS: (FPR_ID_START + 4, D2)  -> S2);
FPR_ALIAS!(D3_ALIAS: (FPR_ID_START + 6, D3)  -> S3);
FPR_ALIAS!(D4_ALIAS: (FPR_ID_START + 8, D4)  -> S4);
FPR_ALIAS!(D5_ALIAS: (FPR_ID_START + 10, D5)  -> S5);
FPR_ALIAS!(D6_ALIAS: (FPR_ID_START + 12, D6)  -> S6);
FPR_ALIAS!(D7_ALIAS: (FPR_ID_START + 14, D7)  -> S7);
FPR_ALIAS!(D8_ALIAS: (FPR_ID_START + 16, D8)  -> S8);
FPR_ALIAS!(D9_ALIAS: (FPR_ID_START + 18, D9)  -> S9);
FPR_ALIAS!(D10_ALIAS: (FPR_ID_START + 20, D10)  -> S10);
FPR_ALIAS!(D11_ALIAS: (FPR_ID_START + 22, D11)  -> S11);
FPR_ALIAS!(D12_ALIAS: (FPR_ID_START + 24, D12)  -> S12);
FPR_ALIAS!(D13_ALIAS: (FPR_ID_START + 26, D13)  -> S13);
FPR_ALIAS!(D14_ALIAS: (FPR_ID_START + 28, D14)  -> S14);
FPR_ALIAS!(D15_ALIAS: (FPR_ID_START + 30, D15)  -> S15);
FPR_ALIAS!(D16_ALIAS: (FPR_ID_START + 32, D16)  -> S16);
FPR_ALIAS!(D17_ALIAS: (FPR_ID_START + 34, D17)  -> S17);
FPR_ALIAS!(D18_ALIAS: (FPR_ID_START + 36, D18)  -> S18);
FPR_ALIAS!(D19_ALIAS: (FPR_ID_START + 38, D19)  -> S19);
FPR_ALIAS!(D20_ALIAS: (FPR_ID_START + 40, D20)  -> S20);
FPR_ALIAS!(D21_ALIAS: (FPR_ID_START + 42, D21)  -> S21);
FPR_ALIAS!(D22_ALIAS: (FPR_ID_START + 44, D22)  -> S22);
FPR_ALIAS!(D23_ALIAS: (FPR_ID_START + 46, D23)  -> S23);
FPR_ALIAS!(D24_ALIAS: (FPR_ID_START + 48, D24)  -> S24);
FPR_ALIAS!(D25_ALIAS: (FPR_ID_START + 50, D25)  -> S25);
FPR_ALIAS!(D26_ALIAS: (FPR_ID_START + 52, D26)  -> S26);
FPR_ALIAS!(D27_ALIAS: (FPR_ID_START + 54, D27)  -> S27);
FPR_ALIAS!(D28_ALIAS: (FPR_ID_START + 56, D28)  -> S28);
FPR_ALIAS!(D29_ALIAS: (FPR_ID_START + 58, D29)  -> S29);
FPR_ALIAS!(D30_ALIAS: (FPR_ID_START + 60, D30)  -> S30);
FPR_ALIAS!(D31_ALIAS: (FPR_ID_START + 62, D31)  -> S31);

lazy_static! {
    pub static ref FPR_ALIAS_TABLE : LinkedHashMap<MuID, Vec<P<Value>>> = {
        let mut ret = LinkedHashMap::new();

        ret.insert(D0.id(), D0_ALIAS.to_vec());
        ret.insert(D1.id(), D1_ALIAS.to_vec());
        ret.insert(D2.id(), D2_ALIAS.to_vec());
        ret.insert(D3.id(), D3_ALIAS.to_vec());
        ret.insert(D4.id(), D4_ALIAS.to_vec());
        ret.insert(D5.id(), D5_ALIAS.to_vec());
        ret.insert(D6.id(), D6_ALIAS.to_vec());
        ret.insert(D7.id(), D7_ALIAS.to_vec());
        ret.insert(D8.id(), D8_ALIAS.to_vec());
        ret.insert(D9.id(), D9_ALIAS.to_vec());
        ret.insert(D10.id(), D10_ALIAS.to_vec());
        ret.insert(D11.id(), D11_ALIAS.to_vec());
        ret.insert(D12.id(), D12_ALIAS.to_vec());
        ret.insert(D13.id(), D13_ALIAS.to_vec());
        ret.insert(D14.id(), D14_ALIAS.to_vec());
        ret.insert(D15.id(), D15_ALIAS.to_vec());
        ret.insert(D16.id(), D16_ALIAS.to_vec());
        ret.insert(D17.id(), D17_ALIAS.to_vec());
        ret.insert(D18.id(), D18_ALIAS.to_vec());
        ret.insert(D19.id(), D19_ALIAS.to_vec());
        ret.insert(D20.id(), D20_ALIAS.to_vec());
        ret.insert(D21.id(), D21_ALIAS.to_vec());
        ret.insert(D22.id(), D22_ALIAS.to_vec());
        ret.insert(D23.id(), D23_ALIAS.to_vec());
        ret.insert(D24.id(), D24_ALIAS.to_vec());
        ret.insert(D25.id(), D25_ALIAS.to_vec());
        ret.insert(D26.id(), D26_ALIAS.to_vec());
        ret.insert(D27.id(), D27_ALIAS.to_vec());
        ret.insert(D28.id(), D28_ALIAS.to_vec());
        ret.insert(D29.id(), D29_ALIAS.to_vec());
        ret.insert(D30.id(), D30_ALIAS.to_vec());
        ret.insert(D31.id(), D31_ALIAS.to_vec());

        ret
    };


    pub static ref FPR_ALIAS_LOOKUP : HashMap<MuID, P<Value>> = {
        let mut ret = HashMap::new();

        for vec in FPR_ALIAS_TABLE.values() {
            let colorable = vec[0].clone();

            for fpr in vec {
                ret.insert(fpr.id(), colorable.clone());
            }
        }

        ret
    };
}

lazy_static!{
    // Same as ARGUMENT_FPRs
    pub static ref RETURN_FPRs : [P<Value>; 8] = [
        D0.clone(),
        D1.clone(),
        D2.clone(),
        D3.clone(),
        D4.clone(),
        D5.clone(),
        D6.clone(),
        D7.clone()
    ];

    pub static ref ARGUMENT_FPRs : [P<Value>; 8] = [
        D0.clone(),
        D1.clone(),
        D2.clone(),
        D3.clone(),
        D4.clone(),
        D5.clone(),
        D6.clone(),
        D7.clone(),
    ];

    pub static ref CALLEE_SAVED_FPRs : [P<Value>; 8] = [
        D8.clone(),
        D9.clone(),
        D10.clone(),
        D11.clone(),
        D12.clone(),
        D13.clone(),
        D14.clone(),
        D15.clone()
    ];

    pub static ref CALLER_SAVED_FPRs : [P<Value>; 24] = [
        D0.clone(),
        D1.clone(),
        D2.clone(),
        D3.clone(),
        D4.clone(),
        D5.clone(),
        D6.clone(),
        D7.clone(),

        D16.clone(),
        D17.clone(),
        D18.clone(),
        D19.clone(),
        D20.clone(),
        D21.clone(),
        D22.clone(),
        D23.clone(),
        D24.clone(),
        D25.clone(),
        D26.clone(),
        D27.clone(),
        D28.clone(),
        D29.clone(),
        D30.clone(),
        D31.clone()
    ];

    static ref ALL_FPRs : [P<Value>; 32] = [
        D0.clone(),
        D1.clone(),
        D2.clone(),
        D3.clone(),
        D4.clone(),
        D5.clone(),
        D6.clone(),
        D7.clone(),

        D8.clone(),
        D9.clone(),
        D10.clone(),
        D11.clone(),
        D12.clone(),
        D13.clone(),
        D14.clone(),
        D15.clone(),

        D16.clone(),
        D17.clone(),
        D18.clone(),
        D19.clone(),
        D20.clone(),
        D21.clone(),
        D22.clone(),
        D23.clone(),
        D24.clone(),
        D25.clone(),
        D26.clone(),
        D27.clone(),
        D28.clone(),
        D29.clone(),
        D30.clone(),
        D31.clone()
    ];
}

lazy_static! {
    pub static ref ALL_MACHINE_REGs : LinkedHashMap<MuID, P<Value>> = {
        let mut map = LinkedHashMap::new();

        for vec in GPR_ALIAS_TABLE.values() {
            for reg in vec {
                map.insert(reg.id(), reg.clone());
            }
        }

        for vec in FPR_ALIAS_TABLE.values() {
            for reg in vec {
                map.insert(reg.id(), reg.clone());
            }
        }

        map
    };

    pub static ref CALLEE_SAVED_REGs : [P<Value>; 18] = [
        X19.clone(),
        X20.clone(),
        X21.clone(),
        X22.clone(),
        X23.clone(),
        X24.clone(),
        X25.clone(),
        X26.clone(),
        X27.clone(),
        X28.clone(),

        // Note: These two are technically CALLEE saved but need to be dealt with specially
        //X29.clone(), // Frame Pointer
        //X30.clone() // Link Register

        D8.clone(),
        D9.clone(),
        D10.clone(),
        D11.clone(),
        D12.clone(),
        D13.clone(),
        D14.clone(),
        D15.clone()
    ];


    // put caller saved regs first (they imposes no overhead if there is no call instruction)
    pub static ref ALL_USABLE_MACHINE_REGs : Vec<P<Value>> = vec![
        X0.clone(),
        X1.clone(),
        X2.clone(),
        X3.clone(),
        X4.clone(),
        X5.clone(),
        X6.clone(),
        X7.clone(),
        X8.clone(),
        X9.clone(),
        X10.clone(),
        X11.clone(),
        X12.clone(),
        X13.clone(),
        X14.clone(),
        X15.clone(),
        X16.clone(),
        X17.clone(),
        // X18.clone(), // Platform Register

        X19.clone(),
        X20.clone(),
        X21.clone(),
        X22.clone(),
        X23.clone(),
        X24.clone(),
        X25.clone(),
        X26.clone(),
        X27.clone(),
        X28.clone(),
        //X29.clone(), // Frame Pointer
        //X30.clone(), // Link Register

        D8.clone(),
        D9.clone(),
        D10.clone(),
        D11.clone(),
        D12.clone(),
        D13.clone(),
        D14.clone(),
        D15.clone(),

        D0.clone(),
        D1.clone(),
        D2.clone(),
        D3.clone(),
        D4.clone(),
        D5.clone(),
        D6.clone(),
        D7.clone(),

        D16.clone(),
        D17.clone(),
        D18.clone(),
        D19.clone(),
        D20.clone(),
        D21.clone(),
        D22.clone(),
        D23.clone(),
        D24.clone(),
        D25.clone(),
        D26.clone(),
        D27.clone(),
        D28.clone(),
        D29.clone(),
        D30.clone(),
        D31.clone()
    ];
}

pub fn init_machine_regs_for_func (func_context: &mut FunctionContext) {
    for reg in ALL_MACHINE_REGs.values() {
        let reg_id = reg.extract_ssa_id().unwrap();
        let entry = SSAVarEntry::new(reg.clone());

        func_context.values.insert(reg_id, entry);
    }
}

pub fn number_of_regs_in_group(group: RegGroup) -> usize {
    match group {
        RegGroup::GPR => ALL_GPRs.len(),
        RegGroup::FPR => ALL_FPRs.len(),
        RegGroup::GPREX => unimplemented!(),
    }
}

pub fn number_of_all_regs() -> usize {
    ALL_MACHINE_REGs.len()
}

pub fn all_regs() -> &'static LinkedHashMap<MuID, P<Value>> {
    &ALL_MACHINE_REGs
}

pub fn all_usable_regs() -> &'static Vec<P<Value>> {
    &ALL_USABLE_MACHINE_REGs
}

pub fn pick_group_for_reg(reg_id: MuID) -> RegGroup {
    let reg = all_regs().get(&reg_id).unwrap();
    if is_int_reg(&reg) {
        RegGroup::GPR
    } else if is_fp_reg(&reg) {
        RegGroup::FPR
    } else {
        panic!("expect a machine reg to be either a GPR or a FPR: {}", reg)
    }
}

// Gets the previouse frame pointer with respect to the current
#[inline(always)]
pub fn get_previous_frame_pointer(frame_pointer: Address) -> Address {
    unsafe { frame_pointer.load::<Address>() }
}

// Gets the return address for the current frame pointer
#[inline(always)]
pub fn get_return_address(frame_pointer: Address) -> Address {
    unsafe { frame_pointer.plus(8).load::<Address>() }
}

// Gets the stack pointer before the current frame was created
#[inline(always)]
pub fn get_previous_stack_pointer(frame_pointer: Address) -> Address {
    frame_pointer.plus(16)
}

#[inline(always)]
pub fn set_previous_frame_pointer(frame_pointer: Address, value: Address) {
    unsafe { frame_pointer.store::<Address>(value) }
}

// Gets the return address for the current frame pointer
#[inline(always)]
pub fn set_return_address(frame_pointer: Address, value: Address) {
    unsafe { frame_pointer.plus(8).store::<Address>(value) }
}

// Reg should be a 64-bit callee saved GPR or FPR
pub fn get_callee_saved_offset(reg: MuID) -> isize {
    debug_assert!(is_callee_saved(reg));
    let id = if reg < FPR_ID_START {
        (reg - CALLEE_SAVED_GPRs[0].id())/2
    } else {
        (reg - CALLEE_SAVED_FPRs[0].id()) / 2 + CALLEE_SAVED_GPRs.len()
    };
    (id as isize + 1)*(-8)
}

// Returns the callee saved register with the id...
/*pub fn get_callee_saved_register(offset: isize) -> P<Value> {
    debug_assert!(offset <= -8 && (-offset) % 8 == 0);
    let id = ((offset/-8) - 1) as usize;
    if id < CALLEE_SAVED_GPRs.len() {
        CALLEE_SAVED_GPRs[id].clone()
    } else if id - CALLEE_SAVED_GPRs.len() < CALLEE_SAVED_FPRs.len() {
        CALLEE_SAVED_FPRs[id - CALLEE_SAVED_GPRs.len()].clone()
    } else {
        panic!("There is no callee saved register with id {}", offset)
    }
}*/

pub fn is_callee_saved(reg_id: MuID) -> bool {

    for reg in CALLEE_SAVED_GPRs.iter() {
        if reg_id == reg.extract_ssa_id().unwrap() {
            return true;
        }
    }

    for reg in CALLEE_SAVED_FPRs.iter() {
        if reg_id == reg.extract_ssa_id().unwrap() {
            return true;
        }
    }
    false
}

// TODO: Check that these numbers are reasonable (THEY ARE ONLY AN ESTIMATE)
use ast::inst::*;
pub fn estimate_insts_for_ir(inst: &Instruction) -> usize {
    use ast::inst::Instruction_::*;

    match inst.v {
        // simple
        BinOp(_, _, _)  => 1,
        BinOpWithStatus(_, _, _, _) => 2,
        CmpOp(_, _, _)  => 1,
        ConvOp{..}      => 1,

        // control flow
        Branch1(_)     => 1,
        Branch2{..}    => 1,
        Select{..}     => 2,
        Watchpoint{..} => 1,
        WPBranch{..}   => 2,
        Switch{..}     => 3,

        // call
        ExprCall{..} | ExprCCall{..} | Call{..} | CCall{..} => 5,
        Return(_)   => 1,
        TailCall(_) => 1,

        // memory access
        Load{..} | Store{..} => 1,
        CmpXchg{..}          => 1,
        AtomicRMW{..}        => 1,
        AllocA(_)            => 1,
        AllocAHybrid(_, _)   => 1,
        Fence(_)             => 1,

        // memory addressing
        GetIRef(_) | GetFieldIRef{..} | GetElementIRef{..} | ShiftIRef{..} | GetVarPartIRef{..} => 0,

        // runtime
        New(_) | NewHybrid(_, _) => 10,
        NewStack(_) | NewThread(_, _) | NewThreadExn(_, _) | NewFrameCursor(_) => 10,
        ThreadExit    => 10,
        Throw(_)      => 10,
        SwapStack{..} => 10,
        CommonInst_GetThreadLocal | CommonInst_SetThreadLocal(_) => 10,
        CommonInst_Pin(_) | CommonInst_Unpin(_) => 10,

        // others
        Move(_) => 0,
        PrintHex(_) => 10,
        SetRetval(_) => 10,
        ExnInstruction{ref inner, ..} => estimate_insts_for_ir(&inner)
    }
}


// Splits an integer immediate into four 16-bit segments (returns the least significant first)
pub fn split_aarch64_imm_u64(val: u64) -> (u16, u16, u16, u16) {
    (val as u16, (val >> 16) as u16, (val >> 32) as u16, (val >> 48) as u16)
}

// Trys to reduce the given floating point to an immediate u64 that can be used with MOVI
pub fn f64_to_aarch64_u64(val: f64) -> Option<u64> {
    use std::mem;
    // WARNING: this assumes a little endian representation
    let bytes: [u8; 8] = unsafe { mem::transmute(val) };

    // Check that each byte is all 1 or all 0
    for i in 0..7 {
        if bytes[i] != 0b11111111 || bytes[i] != 0 {
            return None;
        }
    }

    Some(unsafe {mem::transmute::<f64, u64>(val)})
}

// Check that the given floating point fits in 8 bits
pub fn is_valid_f32_imm(val: f32) -> bool {
    use std::mem;

    // returns true if val has the format:
    //       aBbbbbbc defgh000 00000000 00000000 (where B = !b)
    //index: FEDCBA98 76543210 FEDCBA98 76543210
    //                       1                 0

    let uval = unsafe { mem::transmute::<f32, u32>(val) };

    let b = get_bit(uval as u64, 0x19);

    get_bit(uval as u64, 0x1E) == !b &&
        ((uval & (0b11111 << 0x19)) == if b {0b11111 << 0x19} else {0}) &&
        ((uval & !(0b1111111111111 << 0x13)) == 0)
}

// Reduces the given floating point constant to 8-bits (if it won't loose precision, otherwise returns 0)
pub fn is_valid_f64_imm(val: f64) -> bool {
    use std::mem;

    // returns true if val has the format:
    //       aBbbbbbb bbcdefgh 00000000 00000000 00000000 00000000 00000000 00000000 (where B = !b)
    //index: FEDCBA98 76543210 FEDCBA98 76543210 FEDCBA98 76543210 FEDCBA98 76543210
    //                       3                 2                 1                 0

    let uval = unsafe { mem::transmute::<f64, u64>(val) };

    let b = (uval & (1 << 0x36)) != 0;

    ((uval & (1 << 0x3E)) != 0) == !b &&
        ((uval & (0b11111111 << 0x36)) == if b {0b11111111 << 0x36} else {0}) &&
        ((uval & !(0b1111111111111111 << 0x30)) == 0)

}

// Returns the 'ith bit of x
#[inline(always)]
pub fn get_bit(x: u64, i: usize) -> bool {
    (x & ((1 as u64) << i) ) != 0
}

// Returns true if val = A << S, from some 0 <= A < 4096, and S = 0 or S = 12
pub fn is_valid_arithmetic_imm(val : u64) -> bool {
    val < 4096 || ((val & 0b111111111111) == 0 && val < (4096 << 12))
}

// aarch64 instructions only operate on 32 and 64-bit registers
// so a valid n bit logical immediate (where n < 32) can't be dirrectly used
// this function will replicate the bit pattern so that it can be used
// (the resulting value will be valid iff 'val' is valid, and the lower 'n' bits will equal val)
pub fn replicate_logical_imm(val : u64, n : usize) -> u64 {
    if n < 32 {
        let mut val = val;
        for i in 1..32/n {
            val |= val << i*n;
        }
        val
    } else {
        val
    }
}


// 'val' is a valid logical immediate if the binary value of ROR(val, r) matches the regular expresion
//      (0{k-x}1{x}){m/k}
//      for some r, k that divides N, 2 <= k <= n, and x with 0 < x < k
//      (note: 0 =< r < k);
pub fn is_valid_logical_imm(val : u64, n : usize) -> bool {
    // val should be an 'n' bit number
    debug_assert!(0 < n && n <= 64 && (n == 64 || (val < (1 << n))));
    debug_assert!(n.is_power_of_two());

    // all 0's and all 1's are invalid
    if val == 0 || val == bits_ones(n) {
        return false;
    }

    // find the rightmost '1' with '0' to the right
    let mut r = 0;
    while r < n {
        let current_bit = get_bit(val, r);
        let next_bit = get_bit(val, (r + n - 1) % n);
        if current_bit && !next_bit {
            break;
        }

        r += 1;
    }

    // rotate 'val' so that the MSB is a 0, and the LSB is a 1
    // (since there is a '0' to the right of val[start_index])
    let mut val = val.rotate_right(r as u32);

    // lower n bits ored with the upper n bits
    if n < 64 {
        val = (val & bits_ones(n)) | ((val & (bits_ones(n) << (64 - n))) >> (64 - n))
    }

    let mut x = 0; // number of '1's in a row
    while x < n {
        // found a '0' at position x, there must be x 1's to the right
        if !get_bit(val, x) {
            break;
        }
        x += 1;
    }

    let mut k = x + 1; // where the next '1' is
    while k < n {
        // found a '1'
        if get_bit(val, k) {
            break;
        }
        k += 1;
    }
    // Note: the above may not have found a 1, in which case k == n

    // note: k >= 2, since if k = 1, val = 1....1 (which we've already checked for)
    // check that k divides N
    if n % k != 0 {
        return false;
    }

    // Now we need to check that the pattern (0{k-x}1{x}) is repetead N/K times in val

    let k_mask = bits_ones(k);
    let val_0 = val & k_mask; // the first 'k' bits of val

    // for each N/k expected repitions of val_0 (except the first one_
    for i in 1..(n/k) {
        if val_0 != ((val >> (k*i)) & k_mask) {
            return false; // val_0 dosen't repeat
        }
    }

    return true;
}

// Returns the value of 'val' truncated to 'size', and then zero extended
pub fn get_unsigned_value(val: u64, size: usize) -> u64 {
    (val & bits_ones(size)) as u64 // clears all but the lowest 'size' bits of val
}

// Returns the value of 'val' truncated to 'size', and then sign extended
pub fn get_signed_value(val: u64, size: usize) -> i64 {
    if size == 64 {
        val as i64
    } else {
        let negative = (val & (1 << (size - 1))) != 0;

        if negative {
            (val | (bits_ones(64-size) << size)) as i64 // set the highest '64 - size' bits of val
        } else {
            (val & bits_ones(size)) as i64 // clears all but the lowest 'size' bits of val
        }
    }
}

fn invert_condition_code(cond: &str) -> &'static str {
    match cond {
        "EQ" => "NE",
        "NE" => "EQ",

        "CC" => "CS",
        "CS" => "CV",

        "HS" => "LO",
        "LO" => "HS",

        "MI" => "PL",
        "PL" => "MI",

        "VS" => "VN",
        "VN" => "VS",

        "HI" => "LS",
        "LS" => "HI",

        "GE" => "LT",
        "LT" => "GE",

        "GT" => "LE",
        "LE" => "GT",

        "AL" | "NV" => panic!("AL and NV don't have inverses"),
        _ => panic!("Unrecognised condition code")
    }
}

// Returns the aarch64 condition codes corresponding to the given comparison op
// (the comparisoon is true when the logical or of these conditions is true)
fn get_condition_codes(op: op::CmpOp) -> Vec<&'static str> {
    match op {
        op::CmpOp::EQ  | op::CmpOp::FOEQ => vec!["EQ"],
        op::CmpOp::NE  | op::CmpOp::FUNE => vec!["NE"],
        op::CmpOp::SGT | op::CmpOp::FOGT => vec!["GT"],
        op::CmpOp::SGE | op::CmpOp::FOGE => vec!["GE"],
        op::CmpOp::SLT | op::CmpOp::FULT => vec!["LT"],
        op::CmpOp::SLE | op::CmpOp::FULE => vec!["LE"],
        op::CmpOp::UGT | op::CmpOp::FUGT => vec!["HI"],
        op::CmpOp::UGE | op::CmpOp::FUGE => vec!["HS"],
        op::CmpOp::ULE | op::CmpOp::FOLE => vec!["LS"],
        op::CmpOp::ULT | op::CmpOp::FOLT => vec!["LO"],
        op::CmpOp::FUNO => vec!["VS"],
        op::CmpOp::FORD => vec!["VC"],
        op::CmpOp::FUEQ => vec!["EQ", "VS"],
        op::CmpOp::FONE => vec!["MI", "GT"],

        // These need to be handeled specially
        op::CmpOp::FFALSE => vec![],
        op::CmpOp::FTRUE  => vec![],
    }
}

// if t is a homogenouse floating point aggregate
// (i.e. an array or struct where each element is the same floating-point type, and there are at most 4 elements)
// returns the number of elements, otherwise returns 0

fn hfa_length(t : P<MuType>) -> usize
{
    match t.v {
        MuType_::Struct(ref name) => {
            let read_lock = STRUCT_TAG_MAP.read().unwrap();
            let struc = read_lock.get(name).unwrap();
            let tys = struc.get_tys();
            if tys.len() < 1 || tys.len() > 4 {
                return 0;
            }

            let ref base = tys[0];
            match base.v {
                MuType_::Float | MuType_::Double => {
                    for i in 1..tys.len() - 1 {
                        if tys[i].v != base.v {
                            return 0;
                        }
                    }
                    return tys.len(); // All elements are the same type
                }
                _ => return 0,
            }


        }, // TODO: how do I extra the list of member-types from this??
        MuType_::Array(ref base, n) if n <= 4 => {
            match base.v {
                MuType_::Float | MuType_::Double => n,
                _ => 0
            }
        }
        _ => 0

    }
}

#[inline(always)]
// Returns the number that has 'n' 1's in a row (i.e. 2^n-1)
pub fn bits_ones(n: usize) -> u64 {
    if n == 64 { (-(1 as i64)) as u64 }
        else { (1 << n) - 1 }
}
// val is an unsigned multiple of n and val/n fits in 12 bits
#[inline(always)]
pub fn is_valid_immediate_offset(val: i64, n : usize) -> bool {
    use std;
    let n_align = std::cmp::max(n, 8);
    if n <= 8 {
        (val >= -(1 << 8) && val < (1 << 8)) || // Valid 9 bit signed unscaled offset
            // Valid unsigned 12-bit scalled offset
            (val >= 0 && (val as u64) % (n_align as u64) == 0 && ((val as u64) / (n_align as u64) < (1 << 12)))
    } else { // Will be using a load/store-pair
        // Is val a signed 7 bit multiple of n_align
        (val as u64) % (n_align as u64) == 0  && ((val as u64)/(n_align as u64) < (1 << 7))
    }
}

#[inline(always)]
pub fn is_valid_immediate_scale(val: u64, n : usize) -> bool {
    // if n > 8, then a load pair will be used, and they don't support scales
    n <= 8 && (val == (n as u64) || val == 1)
}

#[inline(always)]
pub fn is_valid_immediate_extension(val: u64) -> bool { val <= 4 }

// Rounds n to the next multiple of d
#[inline(always)]
pub fn round_up(n: usize, d: usize) -> usize { ((n + d - 1)/d)*d }

#[inline(always)]
// Log2, assumes value is a power of two
// TODO: Implement this more efficiently?
pub fn log2(val: u64) -> u64 {
    debug_assert!(val.is_power_of_two());
    debug_assert!(val != 0);
    let mut ret = 0;
    for i in 0..63 {
        if val & (1 << i) != 0 {
            ret = i;
        }
    }
    // WARNING: This will only work for val < 2^31
    //let ret = (val as f64).log2() as u64;
    debug_assert!(val == 1 << ret);
    ret
}

// Gets a primitive integer type with the given alignment
pub fn get_alignment_type(align: usize) -> P<MuType> {
    match align {
        1 => UINT8_TYPE.clone(),
        2 => UINT16_TYPE.clone(),
        4 => UINT32_TYPE.clone(),
        8 => UINT64_TYPE.clone(),
        16 => UINT128_TYPE.clone(),
        _ => panic!("aarch64 dosn't have types with alignment {}", align)
    }
}

#[inline(always)]
pub fn is_zero_register(val: &P<Value>) -> bool {
    is_zero_register_id(val.extract_ssa_id().unwrap())
}

#[inline(always)]
pub fn is_zero_register_id(id: MuID) -> bool {
    id == XZR.extract_ssa_id().unwrap() || id == WZR.extract_ssa_id().unwrap()
}

pub fn match_f32imm(op: &TreeNode) -> bool {
    match op.v {
        TreeNode_::Value(ref pv) => match pv.v {
            Value_::Constant(Constant::Float(_)) => true,
            _ => false
        },
        _ => false
    }
}

pub fn match_f64imm(op: &TreeNode) -> bool {
    match op.v {
        TreeNode_::Value(ref pv) => match pv.v {
            Value_::Constant(Constant::Double(_)) => true,
            _ => false
        },
        _ => false
    }
}

pub fn match_value_f64imm(op: &P<Value>) -> bool {
    match op.v {
        Value_::Constant(Constant::Double(_)) => true,
        _ => false
    }
}

pub fn match_value_f32imm(op: &P<Value>) -> bool {
    match op.v {
        Value_::Constant(Constant::Float(_)) => true,
        _ => false
    }
}

// The type of the node (for a value node)
pub fn node_type(op: &TreeNode) -> P<MuType> {
    match op.v {
        TreeNode_::Instruction(ref inst) => {
            if inst.value.is_some() {
                let ref value = inst.value.as_ref().unwrap();
                if value.len() != 1 {
                    panic!("the node {} does not have one result value", op);
                }

                value[0].ty.clone()
            } else {
                panic!("expected result from the node {}", op);
            }
        }
        TreeNode_::Value(ref pv) => pv.ty.clone(),
    }
}

pub fn match_value_imm(op: &P<Value>) -> bool {
    match op.v {
        Value_::Constant(_) => true,
        _ => false
    }
}

pub fn match_value_int_imm(op: &P<Value>) -> bool {
    match op.v {
        Value_::Constant(Constant::Int(_)) => true,
        _ => false
    }
}

pub fn match_node_value(op: &TreeNode) -> bool {
    match op.v {
        TreeNode_::Value(_) => true,
        _ => false
    }
}

pub fn get_node_value(op: &TreeNode) -> P<Value> {
    match op.v {
        TreeNode_::Value(ref pv) => pv.clone(),
        _ => panic!("Expected node with value")
    }
}

pub fn match_node_int_imm(op: &TreeNode) -> bool {
    match op.v {
        TreeNode_::Value(ref pv) => match_value_int_imm(pv),
        _ => false
    }
}

pub fn match_node_imm(op: &TreeNode) -> bool {
    match op.v {
        TreeNode_::Value(ref pv) => match_value_imm(pv),
        _ => false
    }
}

pub fn node_imm_to_u64(op: &TreeNode) -> u64 {
    match op.v {
        TreeNode_::Value(ref pv) => value_imm_to_u64(pv),
        _ => panic!("expected imm")
    }
}
pub fn node_imm_to_i64(op: &TreeNode, signed: bool) -> u64 {
    match op.v {
        TreeNode_::Value(ref pv) => value_imm_to_i64(pv, signed),
        _ => panic!("expected imm")
    }
}
pub fn node_imm_to_s64(op: &TreeNode) -> i64 {
    match op.v {
        TreeNode_::Value(ref pv) => value_imm_to_s64(pv),
        _ => panic!("expected imm")
    }
}

pub fn node_imm_to_f64(op: &TreeNode) -> f64 {
    match op.v {
        TreeNode_::Value(ref pv) => value_imm_to_f64(pv),
        _ => panic!("expected imm")
    }
}

pub fn node_imm_to_f32(op: &TreeNode) -> f32 {
    match op.v {
        TreeNode_::Value(ref pv) => value_imm_to_f32(pv),
        _ => panic!("expected imm")
    }
}

pub fn node_imm_to_value(op: &TreeNode) -> P<Value> {
    match op.v {
        TreeNode_::Value(ref pv) => {
            pv.clone()
        }
        _ => panic!("expected imm")
    }
}

pub fn value_imm_to_f32(op: &P<Value>) -> f32 {
    match op.v {
        Value_::Constant(Constant::Float(val)) => {
            val as f32
        },
        _ => panic!("expected imm float")
    }
}

pub fn value_imm_to_f64(op: &P<Value>) -> f64 {
    match op.v {
        Value_::Constant(Constant::Double(val)) => {
            val as f64
        },
        _ => panic!("expected imm double")
    }
}

pub fn value_imm_to_u64(op: &P<Value>) -> u64 {
    match op.v {
        Value_::Constant(Constant::Int(val)) =>
            get_unsigned_value(val as u64, op.ty.get_int_length().unwrap()),
        Value_::Constant(Constant::NullRef) => 0,
        _ => panic!("expected imm int")
    }
}

pub fn value_imm_to_i64(op: &P<Value>, signed: bool) -> u64 {
    match op.v {
        Value_::Constant(Constant::Int(val)) =>
            if signed {
                get_signed_value(val as u64, op.ty.get_int_length().unwrap()) as u64
            } else {
                get_unsigned_value(val as u64, op.ty.get_int_length().unwrap())
            },
        Value_::Constant(Constant::NullRef) => 0,
        _ => panic!("expected imm int")
    }
}

pub fn value_imm_to_s64(op: &P<Value>) -> i64 {
    match op.v {
        Value_::Constant(Constant::Int(val)) =>
            get_signed_value(val as u64, op.ty.get_int_length().unwrap()),
        Value_::Constant(Constant::NullRef) => 0,
        _ => panic!("expected imm int")
    }
}

pub fn make_value_int_const(val: u64, vm: &VM) -> P<Value> {
    P(Value {
        hdr: MuEntityHeader::unnamed(vm.next_id()),
        ty: UINT64_TYPE.clone(),
        v: Value_::Constant(Constant::Int(val))
    })
}

// Replaces the zero register with a temporary whose value is zero (or returns the orignal register)
/* TODO use this function for the following arguments:

We can probabbly allow the zero register to be the second argument to an _ext function (as the assembler will simply use the shifted-register encoding, which allows it)
add[,s1] // tirival
add_ext[d, s1]  // trivial
add_imm[d, s1] // trivial

adds[,s1 // not trivial (sets flags)
adds_ext[,s1]   // not trivial (sets flags)
adds_imm[, s2] // not trivial (sets flags)

sub_ext[d, s1]  // trivial
sub_imm[d, s1] // trivial

subs_ext[,s1]   // not trivial (sets flags)
subs_imm[, s2] // not trivial (sets flags)

and_imm[d] // trivial
eor_imm[d] // trivial
orr_imm[d] // trivial

cmn_ext[s1] // not trivial (sets flags)
cmn_imm[s1] // not trivial (sets flags)

cmp_ext[s1] // not trivial (sets flags)
cmp_imm[s1] // not trivial (sets flags)

(they are all (or did I miss some??) places that the SP can be used, which takes up the encoding of the ZR
I believe the Zero register can be used in all other places that an integer register is expected
(BUT AM NOT CERTAIN)
*/

/*
Just insert this immediatly before each emit_XX where XX is one the above instructions,
and arg is the name of the argument that can't be the zero register (do so for each such argument)
let arg = replace_zero_register(backend, &arg, f_context, vm);
*/

pub fn replace_zero_register(backend: &mut CodeGenerator, val: &P<Value>, f_context: &mut FunctionContext, vm: &VM) -> P<Value> {
    if is_zero_register(&val) {
        let temp = make_temporary(f_context, val.ty.clone(), vm);
        backend.emit_mov_imm(&temp, 0);
        temp
    } else {
        val.clone()
    }
}

pub fn make_temporary(f_context: &mut FunctionContext, ty: P<MuType>, vm: &VM) -> P<Value> {
    f_context.make_temporary(vm.next_id(), ty).clone_value()
}

fn emit_mov_f64(backend: &mut CodeGenerator, dest: &P<Value>, f_context: &mut FunctionContext, vm: &VM, val: f64)
{
    use std::mem;
    if val == 0.0 {
        backend.emit_fmov(&dest, &XZR);
    } else if is_valid_f64_imm(val) {
        backend.emit_fmov_imm(&dest, val as f32);
    } else {
        match f64_to_aarch64_u64(val) {
            Some(v) => {
                // Can use a MOVI to load the immediate
                backend.emit_movi(&dest, v);
            }
            None => {
                // Have to load a temporary GPR with the value first
                let tmp_int = make_temporary(f_context, UINT64_TYPE.clone(), vm);
                emit_mov_u64(backend, &tmp_int, unsafe { mem::transmute::<f64, u64>(val) });

                // then move it to an FPR
                backend.emit_fmov(&dest, &tmp_int);
            }
        }
    }
}

fn emit_mov_f32(backend: &mut CodeGenerator, dest: &P<Value>, f_context: &mut FunctionContext, vm: &VM, val: f32)
{
    use std::mem;
    if val == 0.0 {
        backend.emit_fmov(&dest, &WZR);
    } else if is_valid_f32_imm(val) {
        backend.emit_fmov_imm(&dest, val);
    } else {
        // Have to load a temporary GPR with the value first
        let tmp_int = make_temporary(f_context, UINT32_TYPE.clone(), vm);

        emit_mov_u64(backend, &tmp_int, unsafe { mem::transmute::<f32, u32>(val) } as u64);
        // then move it to an FPR
        backend.emit_fmov(&dest, &tmp_int);
    }
}

pub fn emit_mov_u64(backend: &mut CodeGenerator, dest: &P<Value>, val: u64)
{
    let n = dest.ty.get_int_length().unwrap();
    // Can use one instruction
    if n <= 16 {
        backend.emit_movz(&dest, val as u16, 0);
    } else if val == 0 {
        backend.emit_movz(&dest, 0, 0);
    } else if val == (-1i64) as u64 {
        backend.emit_movn(&dest, 0, 0);
    } else if val > 0xFF && is_valid_logical_imm(val, n) {
        // Value is more than 16 bits
        backend.emit_mov_imm(&dest, replicate_logical_imm(val, n));

        // Have to use more than one instruciton
    } else {
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        // Mask val so the higher (unused) bits are cleared
        let val = if n < 64 {
            val & (1 << n) - 1
        } else {
            val
        };
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        // Note n > 16, so there are at least two halfwords in n

        // How many halfowrds are zero or one
        let mut n_zeros = ((val & 0xFF == 0x00) as u64) + ((val & 0xFF00 == 0x0000) as u64);
        let mut n_ones = ((val & 0xFF == 0xFF) as u64) + ((val & 0xFF00 == 0xFF00) as u64);
        if n >= 32 {
            n_zeros += (val & 0xFF0000 == 0xFF0000) as u64;
            n_ones += (val & 0xFF0000 == 0xFF0000) as u64;
            if n >= 48 {
                n_zeros += (val & 0xFF000000 == 0xFF000000) as u64;
                n_ones += (val & 0xFF000000 == 0xFF000000) as u64;
            }
        }

        let (pv0, pv1, pv2, pv3) = split_aarch64_imm_u64(val);
        let mut movzn = false; // whether a movz/movn has been emmited yet

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        if false /*n_ones > n_zeros*/ { // TODO: Fix this??
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            // It will take less instructions to use MOVN
            // MOVN(dest, v, n) will set dest = !(v << n)

            if pv0 != 0xFF {
                backend.emit_movn(&dest, !pv0, 0);
                movzn = true;
            }
            if pv1 != 0xFF {
                if !movzn {
                    backend.emit_movn(&dest, !pv1, 16);
                    movzn = true;
                } else {
                    backend.emit_movk(&dest, pv1, 16);
                }
            }
            if n >= 32 && pv2 != 0xFF {
                if !movzn {
                    backend.emit_movn(&dest, !pv2, 32);
                    movzn = true;
                } else {
                    backend.emit_movk(&dest, pv2, 32);
                }
            }
            if n >= 48 && pv3 != 0xFF {
                if !movzn {
                    backend.emit_movn(&dest, pv3, 48);
                } else {
                    backend.emit_movk(&dest, pv3, 48);
                }
            }
        } else {
            // It will take less instructions to use MOVZ
            // MOVZ(dest, v, n) will set dest = (v << n)
            // MOVK(dest, v, n) will set dest = dest[64-0]:[n];
            if pv0 != 0 {
                backend.emit_movz(&dest, pv0, 0);
                movzn = true;
            }
            if pv1 != 0 {
                if !movzn {
                    backend.emit_movz(&dest, pv1, 16);
                    movzn = true;
                } else {
                    backend.emit_movk(&dest, pv1, 16);
                }
            }
            if n >= 32 && pv2 != 0 {
                if !movzn {
                    backend.emit_movz(&dest, pv2, 32);
                    movzn = true;
                } else {
                    backend.emit_movk(&dest, pv2, 32);
                }
            }
            if n >= 48 && pv3 != 0 {
                if !movzn {
                    backend.emit_movz(&dest, pv3, 48);
                } else {
                    backend.emit_movk(&dest, pv3, 48);
                }
            }
        }
    }
}

// TODO: Will this be correct if src is treated as signed (i think so...)
pub fn emit_mul_u64(backend: &mut CodeGenerator, dest: &P<Value>, src: &P<Value>, f_context: &mut FunctionContext, vm: &VM, val: u64)
{
    if val == 0 {
        // dest = 0
        backend.emit_mov_imm(&dest, 0);
    } else if val == 1 {
        // dest = src
        if dest.id() != src.id() {
            backend.emit_mov(&dest, &src);
        }
    } else if val.is_power_of_two() {
        // dest = src << log2(val)
        backend.emit_lsl_imm(&dest, &src, log2(val as u64) as u8);
    } else {
        // dest = src * val
        let temp_mul = make_temporary(f_context, src.ty.clone(), vm);
        emit_mov_u64(backend, &temp_mul, val as u64);
        backend.emit_mul(&dest, &src, &temp_mul);
    }
}

// Decrement the register by an immediate value
fn emit_sub_u64(backend: &mut CodeGenerator, dest: &P<Value>, src: &P<Value>, f_context: &mut FunctionContext, vm: &VM, val: u64)
{
    if (val as i64) < 0 {
        emit_add_u64(backend, &dest, &src, f_context, vm, (-(val as i64) as u64));
    } else if val == 0 {
        if dest.id() != src.id() {
            backend.emit_mov(&dest, &src);
        }
    } else if is_valid_arithmetic_imm(val) {
        let imm_shift = val > 4096;
        let imm_val = if imm_shift { val >> 12 } else { val };
        backend.emit_sub_imm(&dest, &src, imm_val as u16, imm_shift);
    } else {
        let tmp = make_temporary(f_context, UINT64_TYPE.clone(), vm);
        emit_mov_u64(backend, &tmp, val);
        backend.emit_sub(&dest, &src, &tmp);
    }
}

// Increment the register by an immediate value
fn emit_add_u64(backend: &mut CodeGenerator, dest: &P<Value>, src: &P<Value>, f_context: &mut FunctionContext, vm: &VM, val: u64)
{
    if (val as i64) < 0 {
        emit_sub_u64(backend, &dest, &src, f_context, vm, (-(val as i64) as u64));
    } else if val == 0 {
        if dest.id() != src.id() {
            backend.emit_mov(&dest, &src);
        }
    } else if is_valid_arithmetic_imm(val) {
        let imm_shift = val > 4096;
        let imm_val = if imm_shift { val >> 12 } else { val };
        backend.emit_add_imm(&dest, &src, imm_val as u16, imm_shift);
    } else {
        let tmp = make_temporary(f_context, UINT64_TYPE.clone(), vm);
        emit_mov_u64(backend, &tmp, val);
        backend.emit_add(&dest, &src, &tmp);
    }
}

// dest = src1*val + src2
fn emit_madd_u64(backend: &mut CodeGenerator, dest: &P<Value>, src1: &P<Value>, f_context: &mut FunctionContext, vm: &VM, val: u64, src2: &P<Value>)
{
    if val == 0 {
        // dest = src2
        backend.emit_mov(&dest, &src2);
    } else if val == 1 {
        // dest = src1 + src2
        backend.emit_add(&dest, &src1, &src2);
    } else if val.is_power_of_two() {
        // dest = src1 << log2(val) + src2
        backend.emit_lsl_imm(&dest, &src1, log2(val as u64) as u8);
        backend.emit_add(&dest, &dest, &src2);
    } else {
        // dest = src1 * val + src2
        let temp_mul = make_temporary(f_context, src1.ty.clone(), vm);
        emit_mov_u64(backend, &temp_mul, val as u64);
        backend.emit_madd(&dest, &src1, &temp_mul, &src2);
    }
}
// Compare register with value
fn emit_cmp_u64(backend: &mut CodeGenerator, src1: &P<Value>, f_context: &mut FunctionContext, vm: &VM, val: u64)
{
    if (val as i64) < 0 {
        emit_cmn_u64(backend, &src1, f_context, vm, (-(val as i64) as u64));
    } else if val == 0 {
        // Operation has no effect
    } else if is_valid_arithmetic_imm(val) {
        let imm_shift = val > 4096;
        let imm_val = if imm_shift { val >> 12 } else { val };
        backend.emit_cmp_imm(&src1, imm_val as u16, imm_shift);
    } else {
        let tmp = make_temporary(f_context, UINT64_TYPE.clone(), vm);
        emit_mov_u64(backend, &tmp, val);
        backend.emit_cmp(&src1, &tmp);
    }
}

// Compare register with value
fn emit_cmn_u64(backend: &mut CodeGenerator, src1: &P<Value>, f_context: &mut FunctionContext, vm: &VM, val: u64)
{
    if (val as i64) < 0 {
        emit_cmp_u64(backend, &src1, f_context, vm, (-(val as i64) as u64));
    } else if val == 0 {
        // Operation has no effect
    } else if is_valid_arithmetic_imm(val) {
        let imm_shift = val > 4096;
        let imm_val = if imm_shift { val >> 12 } else { val };
        backend.emit_cmn_imm(&src1, imm_val as u16, imm_shift);
    } else {
        let tmp = make_temporary(f_context, UINT64_TYPE.clone(), vm);
        emit_mov_u64(backend, &tmp, val);
        backend.emit_cmn(&src1, &tmp);
    }
}

// sign extends reg, to fit in a 32/64 bit register
fn emit_sext(backend: &mut CodeGenerator, reg: &P<Value>)
{
    let nreg = check_op_len(&reg.ty); // The size of the aarch64 register
    let nmu = reg.ty.get_int_length().unwrap(); // the size of the Mu type

    // No need to sign extend the zero register
    if nreg > nmu && !is_zero_register(&reg) {
        backend.emit_sbfx(&reg, &reg, 0, nmu as u8);
    }
}

// zero extends reg, to fit in a 32/64 bit register
fn emit_zext(backend: &mut CodeGenerator, reg: &P<Value>)
{
    let nreg = check_op_len(&reg.ty); // The size of the aarch64 register
    let nmu = reg.ty.get_int_length().unwrap(); // the size of the Mu type

    // No need to zero extend the zero register
    if nreg > nmu && !is_zero_register(&reg) {
        backend.emit_ubfx(&reg, &reg, 0, nmu as u8);
    }
}

// one extends reg, to fit in a 32/64 bit register
fn emit_oext(backend: &mut CodeGenerator, reg: &P<Value>)
{
    let nreg = check_op_len(&reg.ty); // The size of the aarch64 register
    let nmu = reg.ty.get_int_length().unwrap(); // the size of the Mu type

    if nreg > nmu {
        if is_zero_register(&reg) {
            unimplemented!(); // Can't one extend the zero register
        }
        backend.emit_orr_imm(&reg, &reg, bits_ones(nreg - nmu) << nmu)
    }
}

// Masks 'src' so that it can be used to shift 'dest'
// Returns a register that should be used for the shift operand (may be dest or src)
fn emit_shift_mask<'b>(backend: &mut CodeGenerator, dest: &'b P<Value>, src: &'b P<Value>) -> &'b P<Value>
{
    let ndest = dest.ty.get_int_length().unwrap() as u64;

    if ndest < 32 { // 16 or 8 bits (need to mask it)
        backend.emit_and_imm(&dest, &src, ndest - 1);
        &dest
    } else {
        &src
    }
}
// TODO: Deal with memory case
fn emit_reg_value(backend: &mut CodeGenerator, pv: &P<Value>, f_context: &mut FunctionContext, vm: &VM) -> P<Value> {
    match pv.v {
        Value_::SSAVar(_) => pv.clone(),
        Value_::Constant(ref c) => {
            match c {
                &Constant::Int(val) => {
                    /*if val == 0 {
                        // TODO emit the zero register (NOTE: it can't be used by all instructions)
                        // Use the zero register (saves having to use a temporary)
                        get_alias_for_length(XZR.id(), get_bit_size(&pv.ty, vm))
                    } else {*/
                    let tmp = make_temporary(f_context, pv.ty.clone(), vm);
                    debug!("tmp's ty: {}", tmp.ty);
                    emit_mov_u64(backend, &tmp, val);
                    tmp
                    //}
                },
                &Constant::IntEx(ref val) => {
                    assert!(val.len() == 2);

                    let tmp = make_temporary(f_context, pv.ty.clone(), vm);
                    let (tmp_l, tmp_h) = split_int128(&tmp, f_context, vm);

                    emit_mov_u64(backend, &tmp_l, val[0]);
                    emit_mov_u64(backend, &tmp_h, val[1]);

                    tmp
                },
                &Constant::FuncRef(func_id) => {
                    let tmp = make_temporary(f_context, pv.ty.clone(), vm);

                    let mem = make_value_symbolic(vm.get_func_name(func_id), true, &ADDRESS_TYPE, vm);
                    emit_calculate_address(backend, &tmp, &mem, f_context, vm);
                    tmp
                },
                &Constant::NullRef => {
                    let tmp = make_temporary(f_context, pv.ty.clone(), vm);
                    backend.emit_mov_imm(&tmp, 0);
                    tmp
                    //get_alias_for_length(XZR.id(), get_bit_size(&pv.ty, vm))
                },
                &Constant::Double(val) => {
                    let tmp = make_temporary(f_context, pv.ty.clone(), vm);
                    emit_mov_f64(backend, &tmp, f_context, vm, val);
                    tmp
                }
                &Constant::Float(val) => {
                    let tmp = make_temporary(f_context, pv.ty.clone(), vm);
                    emit_mov_f32(backend, &tmp, f_context, vm, val);
                    tmp
                },
                _ => panic!("expected fpreg or ireg")
            }
        },
        _ => panic!("expected fpreg or ireg")
    }
}

// TODO: Deal with memory case
pub fn emit_ireg_value(backend: &mut CodeGenerator, pv: &P<Value>, f_context: &mut FunctionContext, vm: &VM) -> P<Value> {
    match pv.v {
        Value_::SSAVar(_) => pv.clone(),
        Value_::Constant(ref c) => {
            match c {
                &Constant::Int(val) => {
                    // TODO Deal with zero case
                    /*if val == 0 {
                        // TODO: Are there any (integer) instructions that can't use the Zero register?
                        // Use the zero register (saves having to use a temporary)
                        get_alias_for_length(XZR.id(), get_bit_size(&pv.ty, vm))
                    } else {*/
                    let tmp = make_temporary(f_context, pv.ty.clone(), vm);
                    debug!("tmp's ty: {}", tmp.ty);
                    emit_mov_u64(backend, &tmp, val);
                    tmp
                    //}
                },
                &Constant::IntEx(ref val) => {
                    assert!(val.len() == 2);

                    let tmp = make_temporary(f_context, pv.ty.clone(), vm);
                    let (tmp_l, tmp_h) = split_int128(&tmp, f_context, vm);

                    emit_mov_u64(backend, &tmp_l, val[0]);
                    emit_mov_u64(backend, &tmp_h, val[1]);

                    tmp
                },
                &Constant::FuncRef(func_id) => {
                    let tmp = make_temporary(f_context, pv.ty.clone(), vm);

                    let mem = make_value_symbolic(vm.get_func_name(func_id), true, &ADDRESS_TYPE, vm);
                    emit_calculate_address(backend, &tmp, &mem, f_context, vm);
                    tmp
                },
                &Constant::NullRef => {
                    let tmp = make_temporary(f_context, pv.ty.clone(), vm);
                    backend.emit_mov_imm(&tmp, 0);
                    tmp
                    //get_alias_for_length(XZR.id(), get_bit_size(&pv.ty, vm))
                },
                _ => panic!("expected ireg")
            }
        },
        _ => panic!("expected ireg")
    }
}

// TODO: Deal with memory case
fn emit_fpreg_value(backend: &mut CodeGenerator, pv: &P<Value>, f_context: &mut FunctionContext, vm: &VM) -> P<Value> {
    match pv.v {
        Value_::SSAVar(_) => pv.clone(),
        Value_::Constant(Constant::Double(val)) => {
            let tmp = make_temporary(f_context, DOUBLE_TYPE.clone(), vm);
            emit_mov_f64(backend, &tmp, f_context, vm, val);
            tmp
        }
        Value_::Constant(Constant::Float(val)) => {
            let tmp = make_temporary(f_context, FLOAT_TYPE.clone(), vm);
            emit_mov_f32(backend, &tmp, f_context, vm, val);
            tmp
        },
        _ => panic!("expected fpreg")
    }
}

fn split_int128(int128: &P<Value>, f_context: &mut FunctionContext, vm: &VM) -> (P<Value>, P<Value>) {
    if f_context.get_value(int128.id()).unwrap().has_split() {
        let vec = f_context.get_value(int128.id()).unwrap().get_split().as_ref().unwrap();
        (vec[0].clone(), vec[1].clone())
    } else {
        let arg_l = make_temporary(f_context, UINT64_TYPE.clone(), vm);
        let arg_h = make_temporary(f_context, UINT64_TYPE.clone(), vm);

        f_context.get_value_mut(int128.id()).unwrap().set_split(vec![arg_l.clone(), arg_h.clone()]);

        (arg_l, arg_h)
    }
}

pub fn emit_ireg_ex_value(backend: &mut CodeGenerator, pv: &P<Value>, f_context: &mut FunctionContext, vm: &VM) -> (P<Value>, P<Value>)  {
    match pv.v {
        Value_::SSAVar(_) => {
            split_int128(pv, f_context, vm)
        },
        Value_::Constant(Constant::IntEx(ref val)) => {
            assert!(val.len() == 2);

            let tmp_l = make_temporary(f_context, UINT64_TYPE.clone(), vm);
            let tmp_h = make_temporary(f_context, UINT64_TYPE.clone(), vm);

            emit_mov_u64(backend, &tmp_l, val[0]);
            emit_mov_u64(backend, &tmp_h, val[1]);

            (tmp_l, tmp_h)
        },
        _ => panic!("expected ireg_ex")
    }
}

pub fn emit_mem(backend: &mut CodeGenerator, pv: &P<Value>, alignment: usize, f_context: &mut FunctionContext, vm: &VM) -> P<Value> {
    match pv.v {
        Value_::Memory(ref mem) => {
            match mem {
                &MemoryLocation::VirtualAddress{ref base, ref offset, scale, signed} => {
                    let mut shift = 0 as u8;
                    let offset =
                        if offset.is_some() {
                            let offset = offset.as_ref().unwrap();
                            if match_value_int_imm(offset) {
                                let mut offset_val = value_imm_to_i64(offset, signed) as i64;
                                offset_val *= scale as i64;

                                if is_valid_immediate_offset(offset_val, alignment) {
                                    Some(make_value_int_const(offset_val as u64, vm))
                                } else if alignment <= 8 {
                                    let offset = make_temporary(f_context, UINT64_TYPE.clone(), vm);
                                    emit_mov_u64(backend, &offset, offset_val as u64);
                                    Some(offset)
                                } else {
                                    // We will be using a store/load pair which dosn't support register offsets
                                    return emit_mem_base(backend, &pv, f_context, vm);
                                }
                            } else {
                                let offset = emit_ireg_value(backend, offset, f_context, vm);

                                // TODO: If scale == (2^n)*m (for some m), set shift = n, and multiply index by m
                                if !is_valid_immediate_scale(scale, alignment) {
                                    let temp = make_temporary(f_context, offset.ty.clone(), vm);

                                    emit_mul_u64(backend, &temp, &offset, f_context, vm, scale);
                                    Some(temp)
                                } else {
                                    shift = log2(scale) as u8;
                                    Some(offset)
                                }
                            }
                        }
                            else {
                                None
                            };

                    P(Value {
                        hdr: MuEntityHeader::unnamed(vm.next_id()),
                        ty: pv.ty.clone(),
                        v: Value_::Memory(MemoryLocation::Address {
                            base: base.clone(),
                            offset: offset,
                            shift: shift,
                            signed: signed
                        })
                    })
                }
                &MemoryLocation::Symbolic{is_global, ..} => {
                    if is_global {
                        let temp = make_temporary(f_context, pv.ty.clone(), vm);
                        emit_addr_sym(backend, &temp, &pv, vm);

                        P(Value {
                            hdr: MuEntityHeader::unnamed(vm.next_id()),
                            ty: pv.ty.clone(),
                            v: Value_::Memory(MemoryLocation::Address {
                                base: temp,
                                offset: None,
                                shift: 0,
                                signed: false,
                            })
                        })
                    } else {
                        pv.clone()
                    }
                }
                _ => pv.clone()
            }
        }
        _ => // Use the value as the base registers
            {
                let tmp_mem = make_value_base_offset(&pv, 0, &pv.ty, vm);
                emit_mem(backend, &tmp_mem, alignment, f_context, vm)
            }
    }
}

// Same as emit_mem except returns a memory location with only a base
// NOTE: This code duplicates allot of code in emit_mem and emit_calculate_address
fn emit_mem_base(backend: &mut CodeGenerator, pv: &P<Value>, f_context: &mut FunctionContext, vm: &VM) -> P<Value> {
    match pv.v {
        Value_::Memory(ref mem) => {
            let base = match mem {
                &MemoryLocation::VirtualAddress{ref base, ref offset, scale, signed} => {
                    if offset.is_some() {
                        let offset = offset.as_ref().unwrap();
                        if match_value_int_imm(offset) {
                            let offset_val = value_imm_to_i64(offset, signed) as i64;
                            if offset_val == 0 {
                                base.clone() // trivial
                            } else {
                                let temp = make_temporary(f_context, pv.ty.clone(), vm);
                                emit_add_u64(backend, &temp, &base, f_context, vm, (offset_val * scale as i64) as u64);
                                temp
                            }
                        } else {
                            let offset = emit_ireg_value(backend, offset, f_context, vm);

                            // TODO: If scale == r*m (for some 0 <= m <= 4), multiply offset by r
                            // then use and add_ext(,...,m)
                            if scale.is_power_of_two() && is_valid_immediate_extension(log2(scale)) {
                                let temp = make_temporary(f_context, pv.ty.clone(), vm);
                                // temp = base + offset << log2(scale)
                                backend.emit_add_ext(&temp, &base, &offset, signed, log2(scale) as u8);
                                temp
                            } else {
                                let temp_offset = make_temporary(f_context, offset.ty.clone(), vm);

                                // temp_offset = offset * scale
                                emit_mul_u64(backend, &temp_offset, &offset, f_context, vm, scale);

                                // Don't need to create a new register, just overwrite temp_offset
                                let temp = cast_value(&temp_offset, &pv.ty);
                                // Need to use add_ext, in case offset is 32-bits
                                backend.emit_add_ext(&temp, &base, &temp_offset, signed, 0);
                                temp
                            }
                        }
                    }
                        else {
                            base.clone() // trivial
                        }
                }
                &MemoryLocation::Address{ref base, ref offset, shift, signed} => {
                    if offset.is_some() {
                        let ref offset = offset.as_ref().unwrap();

                        if match_value_int_imm(&offset) {
                            let offset = value_imm_to_u64(&offset);
                            if offset == 0 {
                                // Offset is 0, it can be ignored
                                base.clone()
                            } else {
                                let temp = make_temporary(f_context, pv.ty.clone(), vm);
                                emit_add_u64(backend, &temp, &base, f_context, vm, offset as u64);
                                temp
                            }
                        } else if RegGroup::get_from_value(&offset) == RegGroup::GPR && offset.is_reg() {
                            let temp = make_temporary(f_context, pv.ty.clone(), vm);
                            backend.emit_add_ext(&temp, &base, &offset, signed, shift);
                            temp
                        } else {
                            panic!("Offset should be an integer register or a constant")
                        }
                    } else {
                        // Simple base address
                        base.clone()
                    }
                }
                &MemoryLocation::Symbolic{..} => {
                    let temp = make_temporary(f_context, pv.ty.clone(), vm);
                    emit_addr_sym(backend, &temp, &pv, vm);
                    temp
                },
            };

            P(Value {
                hdr: MuEntityHeader::unnamed(vm.next_id()),
                ty: pv.ty.clone(),
                v: Value_::Memory(MemoryLocation::Address {
                    base: base.clone(),
                    offset: None,
                    shift: 0,
                    signed: false
                })
            })
        }
        _ => // Use the value as the base register
            {
                let tmp_mem = make_value_base_offset(&pv, 0, &pv.ty, vm);
                emit_mem_base(backend, &tmp_mem, f_context, vm)
            }
    }
}

// Sets 'dest' to the absolute address of the given global symbolic memory location
//WARNING: this assumes that the resulting assembly file is compiled with -fPIC
pub fn emit_addr_sym(backend: &mut CodeGenerator, dest: &P<Value>, src: &P<Value>, vm: &VM) {
    match src.v {
        Value_::Memory(ref mem) => {
            match mem {
                &MemoryLocation::Symbolic{ref label, is_global} => {
                    if is_global {
                        // Set dest to be the page address of the entry for src in the GOT
                        backend.emit_adrp(&dest, &src);

                        // Note: The offset should always be a valid immediate offset as it is 12-bits
                        // (The same size as an immediate offset)
                        let offset = P(Value {
                            hdr: MuEntityHeader::unnamed(vm.next_id()),
                            ty: UINT64_TYPE.clone(),
                            v: Value_::Constant(Constant::ExternSym(format!(":got_lo12:{}", label)))
                        });

                        // [dest + low 12 bits of the GOT entry for src]
                        let address_loc = P(Value {
                            hdr: MuEntityHeader::unnamed(vm.next_id()),
                            ty: ADDRESS_TYPE.clone(),
                            // should be ptr<src.ty>

                            v: Value_::Memory(MemoryLocation::Address {
                                base: dest.clone(),
                                offset: Some(offset),
                                shift: 0,
                                signed: false,
                            })
                        });

                        // Load dest with the value in the GOT entry for src
                        backend.emit_ldr(&dest, &address_loc, false);
                    } else {
                        // Load 'dest' with the value of PC + the PC-offset of src
                        backend.emit_adr(&dest, &src);
                    }
                }
                _ => panic!("Expected symbolic memory location")
            }
        }
        _ => panic!("Expected memory value")
    }
}

fn emit_calculate_address(backend: &mut CodeGenerator, dest: &P<Value>, src: &P<Value>, f_context: &mut FunctionContext, vm: &VM) {
    match src.v {
        Value_::Memory(MemoryLocation::VirtualAddress{ref base, ref offset, scale, signed}) => {
            if offset.is_some() {
                let offset = offset.as_ref().unwrap();
                if match_value_int_imm(offset) {
                    emit_add_u64(backend, &dest, &base, f_context, vm, ((value_imm_to_i64(offset, signed) as i64)*(scale as i64)) as u64);
                } else {
                    // dest = offset * scale + base
                    emit_madd_u64(backend, &dest, &offset, f_context, vm, scale as u64, &base);
                }
            } else {
                backend.emit_mov(&dest, &base)
            }
        }
        // offset(base,index,scale)
        Value_::Memory(MemoryLocation::Address{ref base, ref offset, shift, signed}) => {
            if offset.is_some() {
                let ref offset = offset.as_ref().unwrap();

                if match_value_int_imm(&offset) {
                    let offset = value_imm_to_u64(&offset);
                    if offset == 0 {
                        // Offset is 0, address calculation is trivial
                        backend.emit_mov(&dest, &base);
                    } else {
                        emit_add_u64(backend, &dest, &base, f_context, vm, offset as u64);
                    }
                } else if is_int_reg(&offset) {
                    backend.emit_add_ext(&dest, &base, &offset, signed, shift);
                } else {
                    panic!("Offset should be an integer register or a constant")
                }
            } else {
                // Simple base address
                backend.emit_mov(&dest, &base);
            }
        },

        Value_::Memory(MemoryLocation::Symbolic{..}) => {
            emit_addr_sym(backend, &dest, &src, vm);
        }
        _ => panic!("expect mem location as value")
    }
}

fn make_value_base_offset(base: &P<Value>, offset: i64, ty: &P<MuType>, vm: &VM) -> P<Value> {
    let mem = make_memory_location_base_offset(base, offset, vm);
    make_value_from_memory(mem, ty, vm)
}

fn make_value_from_memory(mem: MemoryLocation, ty: &P<MuType>, vm: &VM) -> P<Value> {
    P(Value {
        hdr: MuEntityHeader::unnamed(vm.next_id()),
        ty: ty.clone(),
        v: Value_::Memory(mem)
    })
}

fn make_memory_location_base_offset(base: &P<Value>, offset: i64, vm: &VM) -> MemoryLocation {
    if offset == 0 {
        MemoryLocation::VirtualAddress{
            base: base.clone(),
            offset: None,
            scale: 1,
            signed: true,
        }
    } else {
        MemoryLocation::VirtualAddress{
            base: base.clone(),
            offset: Some(make_value_int_const(offset as u64, vm)),
            scale: 1,
            signed: true,
        }
    }
}

fn make_memory_location_base_offset_scale(base: &P<Value>, offset: &P<Value>, scale: u64, signed: bool) -> MemoryLocation {
    MemoryLocation::VirtualAddress{
        base: base.clone(),
        offset: Some(offset.clone()),
        scale: scale,
        signed: signed
    }
}

// Returns a memory location that points to 'Base + offset*scale + more_offset'
fn memory_location_shift(backend: &mut CodeGenerator, mem: MemoryLocation, more_offset: i64, f_context: &mut FunctionContext, vm: &VM) -> MemoryLocation {
    if more_offset == 0 {
        return mem; // No need to do anything
    }
    match mem {
        MemoryLocation::VirtualAddress { ref base, ref offset, scale, signed } => {
            let mut new_scale = 1;
            let new_offset =
                if offset.is_some() {
                    let offset = offset.as_ref().unwrap();
                    if match_value_int_imm(&offset) {
                        let offset = offset.extract_int_const()*scale + (more_offset as u64);
                        make_value_int_const(offset as u64, vm)
                    } else {
                        let offset = emit_ireg_value(backend, &offset, f_context, vm);
                        let temp = make_temporary(f_context, offset.ty.clone(), vm);

                        if more_offset % (scale as i64) == 0 {
                            // temp = offset + more_offset/scale
                            emit_add_u64(backend, &temp, &offset, f_context, vm, (more_offset/(scale as i64)) as u64);
                            new_scale = scale;
                        } else {
                            // temp = offset*scale + more_offset
                            emit_mul_u64(backend, &temp, &offset, f_context, vm, scale);
                            emit_add_u64(backend, &temp, &temp, f_context, vm, more_offset as u64);
                        }

                        temp
                    }
                }
                    else {
                        make_value_int_const(more_offset as u64, vm)
                    };

            // if offset was an immediate or more_offset % scale != 0:
            //      new_offset = offset*scale+more_offset
            //      new_scale = 1
            // otherwise:
            //      new_offset = offset + more_offset/scale
            //      new_scale = scale
            // Either way: (new_offset*new_scale) = offset*scale+more_offset
            MemoryLocation::VirtualAddress {
                base: base.clone(),
                offset: Some(new_offset),
                scale: new_scale,
                signed: signed,
            }
        },
        _ => panic!("expected a VirtualAddress memory location")
    }
}

// Returns a memory location that points to 'Base + offset*scale + more_offset*new_scale'
fn memory_location_shift_scale(backend: &mut CodeGenerator, mem: MemoryLocation, more_offset:  &P<Value>, new_scale: u64, f_context: &mut FunctionContext, vm: &VM) -> MemoryLocation {
    if match_value_int_imm(&more_offset) {
        let more_offset = value_imm_to_s64(&more_offset);
        memory_location_shift(backend, mem, more_offset * (new_scale as i64), f_context, vm)
    } else {
        let mut new_scale = new_scale;
        match mem {
            MemoryLocation::VirtualAddress { ref base, ref offset, scale, signed } => {
                let offset =
                    if offset.is_some() {
                        let offset = offset.as_ref().unwrap();
                        if match_value_int_imm(&offset) {
                            let temp = make_temporary(f_context, offset.ty.clone(), vm);
                            let offset_scaled = (offset.extract_int_const() as i64)*(scale as i64);
                            if offset_scaled % (new_scale as i64) == 0 {
                                emit_add_u64(backend, &temp, &more_offset, f_context, vm, (offset_scaled / (new_scale as i64)) as u64);
                                // new_scale*temp = (more_offset + (offset*scale)/new_scale)
                                //                = more_offset*new_scale + offset*scale
                            } else {
                                // temp = more_offset*new_scale + offset*scale
                                emit_mul_u64(backend, &temp, &more_offset, f_context, vm, new_scale);
                                emit_add_u64(backend, &temp, &temp, f_context, vm, offset_scaled as u64);
                                new_scale = 1;
                            }
                            temp
                        } else {
                            let offset = emit_ireg_value(backend, &offset, f_context, vm);
                            let temp = make_temporary(f_context, offset.ty.clone(), vm);

                            if new_scale == scale {
                                // just add the offsets
                                backend.emit_add_ext(&temp, &more_offset, &temp, signed, 0);
                            }  else {
                                // temp = offset * scale
                                emit_mul_u64(backend, &temp, &offset, f_context, vm, scale);

                                if new_scale.is_power_of_two() && is_valid_immediate_extension(log2(new_scale)) {
                                    // temp = (offset * scale) + more_offset << log2(new_scale)
                                    backend.emit_add_ext(&temp, &temp, &more_offset, signed, log2(new_scale) as u8);
                                } else {
                                    // temp_more = more_offset * new_scale
                                    let temp_more = make_temporary(f_context, offset.ty.clone(), vm);
                                    emit_mul_u64(backend, &temp_more, &more_offset, f_context, vm, new_scale);

                                    // temp = (offset * scale) + (more_offset * new_scale);
                                    backend.emit_add_ext(&temp, &temp_more, &temp, signed, 0);
                                }

                                new_scale = 1;
                            }
                            temp
                        }
                    } else {
                        more_offset.clone()
                    };
                MemoryLocation::VirtualAddress {
                    base: base.clone(),
                    offset: Some(offset),
                    scale: new_scale,
                    signed: signed,
                }
            },
            _ => panic!("expected a VirtualAddress memory location")
        }
    }
}

pub fn cast_value(val: &P<Value>, t: &P<MuType>) -> P<Value> {
    let to_size = check_op_len(&val.ty);
    let from_size = check_op_len(&t);
    if to_size == from_size {
        val.clone() // No need to cast
    } else {
        if is_machine_reg(val) {
            if from_size < to_size { // 64 bits to 32 bits
                get_register_from_id(val.id() + 1)
            } else { // 32 bits to 64 bits
                get_register_from_id(val.id() - 1)
            }
        } else {
            unsafe { val.as_type(t.clone()) }
        }
    }
}

fn make_value_symbolic(label: MuName, global: bool, ty: &P<MuType>, vm: &VM) -> P<Value> {
    P(Value {
        hdr: MuEntityHeader::unnamed(vm.next_id()),
        ty : ty.clone(),
        v  : Value_::Memory(MemoryLocation::Symbolic {
            label: label,
            is_global: global
        })
    })
}

fn emit_move_value_to_value(backend: &mut CodeGenerator, dest: &P<Value>, src: &P<Value>, f_context: &mut FunctionContext, vm: &VM) {
    let ref src_ty = src.ty;
    if src_ty.is_scalar() && !src_ty.is_fp() {
        // 128-bit move
        if is_int_ex_reg(&dest) {
            let (dest_l, dest_h) = split_int128(dest, f_context, vm);
            if src.is_int_ex_const() {
                let val = src.extract_int_ex_const();
                assert!(val.len() == 2);

                emit_mov_u64(backend, &dest_l, val[0]);
                emit_mov_u64(backend, &dest_h, val[1]);
            } else if is_int_ex_reg(&src) {
                let (src_l, src_h) = split_int128(src, f_context, vm);

                backend.emit_mov(&dest_l, &src_l);
                backend.emit_mov(&dest_h, &src_h);
            } else if src.is_mem() {
                emit_load(backend, &dest, &src, f_context, vm);
            } else {
                panic!("unexpected gpr mov between {} -> {}", src, dest);
            }
        } else if is_int_reg(&dest) { // gpr mov
            if src.is_int_const() {
                let imm = value_imm_to_u64(src);
                emit_mov_u64(backend, dest, imm);
            } else if is_int_reg(&src) {
                backend.emit_mov(dest, src);
            } else if src.is_mem() {
                emit_load(backend, &dest, &src, f_context, vm);
            } else {
                panic!("unexpected gpr mov between {} -> {}", src, dest);
            }
        } else if dest.is_mem() {
            let temp = emit_ireg_value(backend, src, f_context, vm);
            emit_store(backend, dest, &temp, f_context, vm);
        } else {
            panic!("unexpected gpr mov between {} -> {}", src, dest);
        }
    } else if src_ty.is_scalar() && src_ty.is_fp() {
        // fpr mov
        if is_fp_reg(&dest) {
            if match_value_f32imm(src) {
                let src = value_imm_to_f32(src);
                emit_mov_f32(backend, dest, f_context, vm, src);
            } else if match_value_f64imm(src) {
                let src = value_imm_to_f64(src);
                emit_mov_f64(backend, dest, f_context, vm, src);
            } else if is_fp_reg(&src) {
                backend.emit_fmov(dest, src);
            } else if src.is_mem() {
                emit_load(backend, &dest, &src, f_context, vm);
            } else {
                panic!("unexpected gpr mov between {} -> {}", src, dest);
            }
        } else if dest.is_mem() {
            let temp = emit_fpreg_value(backend, src, f_context, vm);
            emit_store(backend, dest, &temp, f_context, vm);
        } else {
            panic!("unexpected fpr mov between {} -> {}", src, dest);
        }
    } else {
        panic!("unexpected mov of type {}", src_ty)
    }
}

fn emit_load(backend: &mut CodeGenerator, dest: &P<Value>, src: &P<Value>, f_context: &mut FunctionContext, vm: &VM) {
    let src = emit_mem(backend, &src, get_type_alignment(&dest.ty, vm), f_context, vm);
    if is_int_reg(dest) || is_fp_reg(dest) {
        backend.emit_ldr(&dest, &src, false);
    } else if is_int_ex_reg(dest) {
        let (dest_l, dest_h) = emit_ireg_ex_value(backend, dest, f_context, vm);
        backend.emit_ldp(&dest_l, &dest_h, &src);
    } else {
        unimplemented!();
    }

}

fn emit_store(backend: &mut CodeGenerator, dest: &P<Value>, src: &P<Value>, f_context: &mut FunctionContext, vm: &VM) {
    let dest = emit_mem(backend, &dest, get_type_alignment(&src.ty, vm), f_context, vm);
    if is_int_reg(src) || is_fp_reg(src) {
        backend.emit_str(&dest, &src);
    } else if is_int_ex_reg(src) {
        let (src_l, src_h) = emit_ireg_ex_value(backend, src, f_context, vm);
        backend.emit_stp(&dest, &src_l, &src_h);
    } else {
        unimplemented!();
    }
}

fn emit_load_base_offset(backend: &mut CodeGenerator, dest: &P<Value>, base: &P<Value>, offset: i64, f_context: &mut FunctionContext, vm: &VM) -> P<Value> {
    let mem = make_value_base_offset(base, offset, &dest.ty, vm);
    emit_load(backend, dest, &mem, f_context, vm);
    mem
}

fn emit_store_base_offset(backend: &mut CodeGenerator, base: &P<Value>, offset: i64, src: &P<Value>, f_context: &mut FunctionContext, vm: &VM) {
    let mem = make_value_base_offset(base, offset, &src.ty, vm);
    emit_store(backend, &mem, src, f_context, vm);
}


fn is_int_reg(val: &P<Value>) -> bool
{
    RegGroup::get_from_value(&val) == RegGroup::GPR && (val.is_reg() || val.is_const