inst_sel.rs

// 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.

use ast::ir::*;
use ast::ptr::*;
use ast::inst::*;
use ast::op;
use ast::op::*;
use ast::types::*;
use vm::VM;
use runtime::mm;
use runtime::mm::OBJECT_HEADER_SIZE;
use runtime::mm::OBJECT_HEADER_OFFSET;
use runtime::ValueLocation;
use runtime::thread;
use runtime::entrypoints;
use runtime::entrypoints::RuntimeEntrypoint;

use compiler::CompilerPass;
use compiler::backend::BackendType;
use compiler::backend::RegGroup;
use compiler::backend::PROLOGUE_BLOCK_NAME;
use compiler::backend::x86_64;
use compiler::backend::x86_64::CodeGenerator;
use compiler::backend::x86_64::ASMCodeGen;
use compiler::machine_code::CompiledFunction;
use compiler::frame::Frame;

use utils::math;
use utils::POINTER_SIZE;

use std::collections::HashMap;
use std::collections::LinkedList;

use std::any::Any;

lazy_static! {
    /// struct<int32, int32, int32, int32>
    static ref LONG_4_TYPE : P<MuType> = P(
        MuType::new(new_internal_id(), MuType_::mustruct(Mu("long_4"), vec![UINT32_TYPE.clone(); 4]))
    );

    /// constant for converting unsigned integer to floating point
    static ref UITOFP_C0 : P<Value> = P(Value{
        hdr: MuEntityHeader::named(new_internal_id(), Mu("UITOFP_C0")),
        ty : LONG_4_TYPE.clone(),
        v  : Value_::Constant(Constant::List(vec![
            P(Value{
                hdr: MuEntityHeader::unnamed(new_internal_id()),
                ty: UINT32_TYPE.clone(),
                v : Value_::Constant(Constant::Int(1127219200u64))
            }),
            P(Value{
                hdr: MuEntityHeader::unnamed(new_internal_id()),
                ty: UINT32_TYPE.clone(),
                v : Value_::Constant(Constant::Int(1160773632u64))
            }),
            P(Value{
                hdr: MuEntityHeader::unnamed(new_internal_id()),
                ty: UINT32_TYPE.clone(),
                v : Value_::Constant(Constant::Int(0u64))
            }),
            P(Value{
                hdr: MuEntityHeader::unnamed(new_internal_id()),
                ty: UINT32_TYPE.clone(),
                v : Value_::Constant(Constant::Int(0u64))
            })
        ]))
    });

    /// struct<int64, int64>
    static ref QUAD_2_TYPE : P<MuType> = P(
        MuType::new(new_internal_id(), MuType_::mustruct(Mu("quad_2"), vec![UINT64_TYPE.clone(); 2]))
    );

    /// constant for converting unsigned integer to floating point
    static ref UITOFP_C1 : P<Value> = P(Value{
        hdr: MuEntityHeader::named(new_internal_id(), Mu("UITOFP_C1")),
        ty : QUAD_2_TYPE.clone(),
        v  : Value_::Constant(Constant::List(vec![
            P(Value{
                hdr: MuEntityHeader::unnamed(new_internal_id()),
                ty: UINT64_TYPE.clone(),
                v : Value_::Constant(Constant::Int(4841369599423283200u64))
            }),
            P(Value{
                hdr: MuEntityHeader::unnamed(new_internal_id()),
                ty: UINT64_TYPE.clone(),
                v : Value_::Constant(Constant::Int(4985484787499139072u64))
            })
        ]))
    });

    /// constant for converting double to unsigned integer
    static ref FPTOUI_C_DOUBLE : P<Value> = P(Value{
        hdr: MuEntityHeader::named(new_internal_id(), Mu("FPTOUI_C_DOUBLE")),
        ty : UINT64_TYPE.clone(),
        v  : Value_::Constant(Constant::Int(4890909195324358656u64))
    });

    /// constant for converting float to unsigned integer
    pub static ref FPTOUI_C_FLOAT : P<Value> = P(Value{
        hdr: MuEntityHeader::named(new_internal_id(), Mu("FPTOUI_C_FLOAT")),
        ty : UINT32_TYPE.clone(),
        v  : Value_::Constant(Constant::Int(1593835520u64))
    });
}

/// for some IR instructions, we need a call into runtime
/// for efficiency, we may emit runtime fastpath directly in assembly
//  FIXME: we should have a separate pass to rewrite the instruction into a fastpath (in IR),
//         and a call to slowpath, then instruction selection (see Issue#6)
const INLINE_FASTPATH : bool = false;

pub struct InstructionSelection {
    name: &'static str,
    /// backend code generator
    backend: Box<CodeGenerator>,

    // information about the function being compiled

    /// ID of current function version being compiled
    current_fv_id: MuID,
    /// used to create a unique callsite ID for current function
    current_callsite_id: usize,
    /// frame for current function
    current_frame: Option<Frame>,
    /// block that is currently being compiled
    /// the block may be created during instruction selection
    current_block: Option<MuName>,
    /// IR block that is currently being compiled
    /// use this block name to trace some information at IR level
    current_block_in_ir: Option<MuName>,
    /// start location of current function
    current_func_start: Option<ValueLocation>,
    /// technically this is a map in that each Key is unique, but we will never try and add duplicate
    /// keys, or look things up, so a list of pairs is faster than a Map.
    /// A list of pairs, the first is the name of a callsite the second
    current_callsites: LinkedList<(MuName, MuID)>,
    /// a map of exception blocks
    /// key: block id, val: block location
    current_exn_blocks: HashMap<MuID, MuName>,
    /// constants used in this function that are put to memory
    /// key: value id, val: constant value
    current_constants: HashMap<MuID, P<Value>>,
    /// constants used in this function that are put to memory
    /// key: value id, val: memory location
    current_constants_locs: HashMap<MuID, P<Value>>
}

impl <'a> InstructionSelection {
    #[cfg(feature = "aot")]
    pub fn new() -> InstructionSelection {
        InstructionSelection{
            name: "Instruction Selection (x64)",
            backend: Box::new(ASMCodeGen::new()),

            current_fv_id: 0,
            current_callsite_id: 0,
            current_frame: None,
            current_block: None,        // which block we are generating code for
            current_block_in_ir: None,  // it is possible the block is newly created in instruction selection
                                        // but sometimes we want to know its control flow
                                        // so we need to track what block it is from the IR

                                        // FIXME: ideally we should not create new blocks in instruction selection
                                        // see Issue #6
            current_func_start: None,
            current_callsites: LinkedList::new(),
            current_exn_blocks: HashMap::new(),

            current_constants: HashMap::new(),
            current_constants_locs: HashMap::new()
        }
    }

    #[cfg(feature = "jit")]
    pub fn new() -> InstructionSelection {
        unimplemented!()
    }

    /// we use hand-written pattern matching rules for instruction selection
    /// for a pattern that can match several rules, the first rule met will be executed, and chosen.
    fn instruction_select(&mut self, node: &'a TreeNode, f_content: &FunctionContent, f_context: &mut FunctionContext, vm: &VM) {
        trace!("instsel on node#{} {}", node.id(), node);
        
        match node.v {
            TreeNode_::Instruction(ref inst) => {
                match inst.v {
                    Instruction_::Branch2{cond, ref true_dest, ref false_dest, ..} => {
                        trace!("instsel on BRANCH2");
                        // 'branch_if_true' == true, we emit cjmp the same as CmpOp  (je  for EQ, jne for NE)
                        // 'branch_if_true' == false, we emit opposite cjmp as CmpOp (jne for EQ, je  for NE)
                        // FIXME: we should move this to machine independent code
                        // e.g. as a subpass after trace scheduling, see Issue#27
                        let (fallthrough_dest, branch_dest, branch_if_true) = {
                            // get current block and next block in trace (fallthrough block)
                            let cur_block = f_content.get_block_by_name(self.current_block_in_ir.as_ref().unwrap().clone());
                            let next_block_in_trace = cur_block.control_flow.get_hottest_succ().unwrap();

                            if next_block_in_trace == true_dest.target {
                                (true_dest, false_dest, false)
                            } else {
                                (false_dest, true_dest, true)
                            }
                        };
                        
                        let ref ops = inst.ops;
                        self.process_dest(&ops, fallthrough_dest, f_content, f_context, vm);
                        self.process_dest(&ops, branch_dest, f_content, f_context, vm);
                        
                        let branch_target = f_content.get_block(branch_dest.target).name().unwrap();
    
                        let ref cond = ops[cond];
                        if self.match_cmp_res(cond) {
                            // this branch2's cond is from a comparison result
                            trace!("emit cmp_res-branch2");
                            match self.emit_cmp_res(cond, f_content, f_context, vm) {
                                op::CmpOp::EQ => {
                                    if branch_if_true {
                                        self.backend.emit_je(branch_target);
                                    } else {
                                        self.backend.emit_jne(branch_target);
                                    }
                                },
                                op::CmpOp::NE => {
                                    if branch_if_true {
                                        self.backend.emit_jne(branch_target);
                                    } else {
                                        self.backend.emit_je(branch_target);
                                    }
                                },
                                op::CmpOp::UGE => {
                                    if branch_if_true {
                                        self.backend.emit_jae(branch_target);
                                    } else {
                                        self.backend.emit_jb(branch_target);
                                    }
                                },
                                op::CmpOp::UGT => {
                                    if branch_if_true {
                                        self.backend.emit_ja(branch_target);
                                    } else {
                                        self.backend.emit_jbe(branch_target);
                                    }
                                },
                                op::CmpOp::ULE => {
                                    if branch_if_true {
                                        self.backend.emit_jbe(branch_target);
                                    } else {
                                        self.backend.emit_ja(branch_target);
                                    }
                                },
                                op::CmpOp::ULT => {
                                    if branch_if_true {
                                        self.backend.emit_jb(branch_target);
                                    } else {
                                        self.backend.emit_jae(branch_target);
                                    }
                                },
                                op::CmpOp::SGE => {
                                    if branch_if_true {
                                        self.backend.emit_jge(branch_target);
                                    } else {
                                        self.backend.emit_jl(branch_target);
                                    }
                                },
                                op::CmpOp::SGT => {
                                    if branch_if_true {
                                        self.backend.emit_jg(branch_target);
                                    } else {
                                        self.backend.emit_jle(branch_target);
                                    }
                                },
                                op::CmpOp::SLE => {
                                    if branch_if_true {
                                        self.backend.emit_jle(branch_target);
                                    } else {
                                        self.backend.emit_jg(branch_target);
                                    }
                                },
                                op::CmpOp::SLT => {
                                    if branch_if_true {
                                        self.backend.emit_jl(branch_target);
                                    } else {
                                        self.backend.emit_jge(branch_target);
                                    }
                                },

                                // floating point

                                op::CmpOp::FOEQ | op::CmpOp::FUEQ => {
                                    if branch_if_true {
                                        self.backend.emit_je(branch_target);
                                    } else {
                                        self.backend.emit_jne(branch_target);
                                    }
                                },
                                op::CmpOp::FONE | op::CmpOp::FUNE => {
                                    if branch_if_true {
                                        self.backend.emit_jne(branch_target);
                                    } else {
                                        self.backend.emit_je(branch_target);
                                    }
                                },
                                op::CmpOp::FOGT | op::CmpOp::FUGT => {
                                    if branch_if_true {
                                        self.backend.emit_ja(branch_target);
                                    } else {
                                        self.backend.emit_jbe(branch_target);
                                    }
                                },
                                op::CmpOp::FOGE | op::CmpOp::FUGE => {
                                    if branch_if_true {
                                        self.backend.emit_jae(branch_target);
                                    } else {
                                        self.backend.emit_jb(branch_target);
                                    }
                                },
                                op::CmpOp::FOLT | op::CmpOp::FULT => {
                                    if branch_if_true {
                                        self.backend.emit_jb(branch_target);
                                    } else {
                                        self.backend.emit_jae(branch_target);
                                    }
                                },
                                op::CmpOp::FOLE | op::CmpOp::FULE => {
                                    if branch_if_true {
                                        self.backend.emit_jbe(branch_target);
                                    } else {
                                        self.backend.emit_ja(branch_target);
                                    }
                                },

                                _ => unimplemented!()
                            }
                        } else if self.match_ireg(cond) {
                            // this branch2 cond is a temporary with value, or an instruction that
                            // emits a temporary
                            trace!("emit ireg-branch2");
                            
                            let cond_reg = self.emit_ireg(cond, f_content, f_context, vm);
                            
                            // emit: cmp cond_reg 1
                            self.backend.emit_cmp_imm_r(1, &cond_reg);
                            // emit: je #branch_dest
                            if branch_if_true {
                                self.backend.emit_je(branch_target);
                            } else {
                                self.backend.emit_jne(branch_target);
                            }
                        } else {
                            panic!("unexpected cond in BRANCH2: {}", cond)
                        }

                        // it is possible that the fallthrough block is scheduled somewhere else
                        // we need to explicitly jump to it (this jump will get eliminated in
                        // peephole pass if the fallthrough block immediate follows the jump)
                        self.finish_block();

                        let fallthrough_temp_block = format!("{}_{}_branch_fallthrough", self.current_fv_id, node.id());
                        self.start_block(fallthrough_temp_block);

                        let fallthrough_target = f_content.get_block(fallthrough_dest.target).name().unwrap();
                        self.backend.emit_jmp(fallthrough_target);
                    },

                    Instruction_::Select{cond, true_val, false_val} => {
                        use ast::op::CmpOp::*;

                        trace!("instsel on SELECT");
                        let ref ops = inst.ops;

                        let ref cond = ops[cond];
                        let ref true_val = ops[true_val];
                        let ref false_val = ops[false_val];

                        // generate comparison
                        let cmpop = if self.match_cmp_res(cond) {
                            self.emit_cmp_res(cond, f_content, f_context, vm)
                        } else if self.match_ireg(cond) {
                            let tmp_cond = self.emit_ireg(cond, f_content, f_context, vm);
                            // emit: cmp cond_reg 1
                            self.backend.emit_cmp_imm_r(1, &tmp_cond);

                            EQ
                        } else {
                            panic!("expected cond to be ireg, found {}", cond)
                        };

                        // emit code to move values
                        if self.match_ireg(true_val) {
                            // moving integers/pointers
                            let tmp_res   = self.get_result_value(node);

                            // use cmov for 16/32/64bit integer
                            // use jcc  for 8 bit
                            // FIXME: could use 32bit register to implement 8bit select
                            match tmp_res.ty.get_int_length() {
                                // cmov
                                Some(len) if len > 8 => {
                                    let tmp_true  = self.emit_ireg(true_val, f_content, f_context, vm);
                                    let tmp_false = self.emit_ireg(false_val, f_content, f_context, vm);

                                    // mov tmp_false -> tmp_res
                                    self.backend.emit_mov_r_r(&tmp_res, &tmp_false);

                                    match cmpop {
                                        EQ  => self.backend.emit_cmove_r_r (&tmp_res, &tmp_true),
                                        NE  => self.backend.emit_cmovne_r_r(&tmp_res, &tmp_true),
                                        SGE => self.backend.emit_cmovge_r_r(&tmp_res, &tmp_true),
                                        SGT => self.backend.emit_cmovg_r_r (&tmp_res, &tmp_true),
                                        SLE => self.backend.emit_cmovle_r_r(&tmp_res, &tmp_true),
                                        SLT => self.backend.emit_cmovl_r_r (&tmp_res, &tmp_true),
                                        UGE => self.backend.emit_cmovae_r_r(&tmp_res, &tmp_true),
                                        UGT => self.backend.emit_cmova_r_r (&tmp_res, &tmp_true),
                                        ULE => self.backend.emit_cmovbe_r_r(&tmp_res, &tmp_true),
                                        ULT => self.backend.emit_cmovb_r_r (&tmp_res, &tmp_true),

                                        FOEQ | FUEQ => self.backend.emit_cmove_r_r (&tmp_res, &tmp_true),
                                        FONE | FUNE => self.backend.emit_cmovne_r_r(&tmp_res, &tmp_true),
                                        FOGT | FUGT => self.backend.emit_cmova_r_r (&tmp_res, &tmp_true),
                                        FOGE | FUGE => self.backend.emit_cmovae_r_r(&tmp_res, &tmp_true),
                                        FOLT | FULT => self.backend.emit_cmovb_r_r (&tmp_res, &tmp_true),
                                        FOLE | FULE => self.backend.emit_cmovbe_r_r(&tmp_res, &tmp_true),

                                        // FFALSE/FTRUE unimplemented
                                        _ => unimplemented!()
                                    }
                                }
                                // jcc - for 8-bits integer
                                _ => {
                                    let blk_true  = format!("{}_{}_select_true",  self.current_fv_id, node.id());
                                    let blk_false = format!("{}_{}_select_false", self.current_fv_id, node.id());
                                    let blk_end   = format!("{}_{}_select_end",   self.current_fv_id, node.id());

                                    // jump to blk_true if true
                                    match cmpop {
                                        EQ  => self.backend.emit_je (blk_true.clone()),
                                        NE  => self.backend.emit_jne(blk_true.clone()),
                                        SGE => self.backend.emit_jge(blk_true.clone()),
                                        SGT => self.backend.emit_jg (blk_true.clone()),
                                        SLE => self.backend.emit_jle(blk_true.clone()),
                                        SLT => self.backend.emit_jl (blk_true.clone()),
                                        UGE => self.backend.emit_jae(blk_true.clone()),
                                        UGT => self.backend.emit_ja (blk_true.clone()),
                                        ULE => self.backend.emit_jbe(blk_true.clone()),
                                        ULT => self.backend.emit_jb (blk_true.clone()),

                                        FOEQ | FUEQ => self.backend.emit_je (blk_true.clone()),
                                        FONE | FUNE => self.backend.emit_jne(blk_true.clone()),
                                        FOGT | FUGT => self.backend.emit_ja (blk_true.clone()),
                                        FOGE | FUGE => self.backend.emit_jae(blk_true.clone()),
                                        FOLT | FULT => self.backend.emit_jb (blk_true.clone()),
                                        FOLE | FULE => self.backend.emit_jbe(blk_true.clone()),

                                        // FFALSE/FTRUE unimplemented
                                        _ => unimplemented!()
                                    }

                                    // finishing current block
                                    self.finish_block();

                                    // blk_false:
                                    self.start_block(blk_false.clone());
                                    // mov false result here
                                    self.emit_move_node_to_value(&tmp_res, &false_val, f_content, f_context, vm);
                                    // jmp to end
                                    self.backend.emit_jmp(blk_end.clone());
                                    // finishing current block
                                    self.finish_block();

                                    // blk_true:
                                    self.start_block(blk_true.clone());
                                    // mov true value -> result
                                    self.emit_move_node_to_value(&tmp_res, &true_val, f_content, f_context, vm);
                                    self.finish_block();

                                    // blk_end:
                                    self.start_block(blk_end.clone());
                                }
                            }
                        } else if self.match_fpreg(true_val) {
                            let tmp_res = self.get_result_value(node);

                            let blk_true  = format!("{}_{}_select_true",  self.current_fv_id, node.id());
                            let blk_false = format!("{}_{}_select_false", self.current_fv_id, node.id());
                            let blk_end   = format!("{}_{}_select_end",   self.current_fv_id, node.id());

                            // jump to blk_true if true
                            match cmpop {
                                EQ  => self.backend.emit_je (blk_true.clone()),
                                NE  => self.backend.emit_jne(blk_true.clone()),
                                SGE => self.backend.emit_jge(blk_true.clone()),
                                SGT => self.backend.emit_jg (blk_true.clone()),
                                SLE => self.backend.emit_jle(blk_true.clone()),
                                SLT => self.backend.emit_jl (blk_true.clone()),
                                UGE => self.backend.emit_jae(blk_true.clone()),
                                UGT => self.backend.emit_ja (blk_true.clone()),
                                ULE => self.backend.emit_jbe(blk_true.clone()),
                                ULT => self.backend.emit_jb (blk_true.clone()),

                                FOEQ | FUEQ => self.backend.emit_je (blk_true.clone()),
                                FONE | FUNE => self.backend.emit_jne(blk_true.clone()),
                                FOGT | FUGT => self.backend.emit_ja (blk_true.clone()),
                                FOGE | FUGE => self.backend.emit_jae(blk_true.clone()),
                                FOLT | FULT => self.backend.emit_jb (blk_true.clone()),
                                FOLE | FULE => self.backend.emit_jbe(blk_true.clone()),

                                _ => unimplemented!()
                            }

                            // finishing current block
                            self.finish_block();

                            // blk_false:
                            self.start_block(blk_false.clone());
                            // mov false result here
                            self.emit_move_node_to_value(&tmp_res, &false_val, f_content, f_context, vm);
                            // jmp to end
                            self.backend.emit_jmp(blk_end.clone());

                            // finishing current block
                            self.finish_block();

                            // blk_true:
                            self.start_block(blk_true.clone());
                            // mov true value -> result
                            self.emit_move_node_to_value(&tmp_res, &true_val, f_content, f_context, vm);
                            self.finish_block();

                            // blk_end:
                            self.start_block(blk_end.clone());
                        } else {
                            unimplemented!()
                        }
                    },

                    Instruction_::CmpOp(_, _, _) => {
                        use ast::op::CmpOp::*;
                        trace!("instsel on CMPOP");

                        let tmp_res = self.get_result_value(node);
                        assert!(tmp_res.ty.get_int_length().is_some());
                        assert!(tmp_res.ty.get_int_length().unwrap() == 1);

                        // set byte to result
                        match self.emit_cmp_res(node, f_content, f_context, vm) {
                            EQ  => self.backend.emit_sete_r (&tmp_res),
                            NE  => self.backend.emit_setne_r(&tmp_res),
                            SGE => self.backend.emit_setge_r(&tmp_res),
                            SGT => self.backend.emit_setg_r (&tmp_res),
                            SLE => self.backend.emit_setle_r(&tmp_res),
                            SLT => self.backend.emit_setl_r (&tmp_res),
                            UGE => self.backend.emit_setae_r(&tmp_res),
                            UGT => self.backend.emit_seta_r (&tmp_res),
                            ULE => self.backend.emit_setbe_r(&tmp_res),
                            ULT => self.backend.emit_setb_r (&tmp_res),

                            FOEQ | FUEQ => self.backend.emit_sete_r (&tmp_res),
                            FONE | FUNE => self.backend.emit_setne_r(&tmp_res),
                            FOGT | FUGT => self.backend.emit_seta_r (&tmp_res),
                            FOGE | FUGE => self.backend.emit_setae_r(&tmp_res),
                            FOLT | FULT => self.backend.emit_setb_r (&tmp_res),
                            FOLE | FULE => self.backend.emit_setbe_r(&tmp_res),

                            // FFALSE/FTRUE
                            _ => unimplemented!()
                        }
                    }

                    Instruction_::Branch1(ref dest) => {
                        trace!("instsel on BRANCH1");
                        let ref ops = inst.ops;
                                            
                        self.process_dest(&ops, dest, f_content, f_context, vm);
                        
                        let target = f_content.get_block(dest.target).name().unwrap();
                        // jmp
                        self.backend.emit_jmp(target);
                    },

                    Instruction_::Switch{cond, ref default, ref branches} => {
                        trace!("instsel on SWITCH");
                        let ref ops = inst.ops;
                        let ref cond = ops[cond];

                        if self.match_ireg(cond) {
                            let tmp_cond = self.emit_ireg(cond, f_content, f_context, vm);

                            // currently implementing switch as cascading conditional branch
                            // This is slow if there are many 'case' arms. We should consider
                            // using a switch table

                            // emit each branch
                            for &(case_op_index, ref case_dest) in branches {
                                let ref case_op = ops[case_op_index];

                                // process dest
                                self.process_dest(&ops, case_dest, f_content, f_context, vm);

                                let target = f_content.get_block(case_dest.target).name().unwrap();

                                if self.match_iimm(case_op) {
                                    let imm = self.node_iimm_to_i32(case_op);

                                    // cmp case cond
                                    self.backend.emit_cmp_imm_r(imm, &tmp_cond);
                                    // je dest
                                    self.backend.emit_je(target);
                                } else if self.match_ireg(case_op) {
                                    let tmp_case_op = self.emit_ireg(case_op, f_content, f_context, vm);

                                    // cmp case cond
                                    self.backend.emit_cmp_r_r(&tmp_case_op, &tmp_cond);
                                    // je dest
                                    self.backend.emit_je(target);
                                } else {
                                    panic!("expecting ireg cond to be either iimm or ireg: {}", cond);
                                }

                                self.finish_block();
                                self.start_block(format!("{}_switch_not_met_case_{}", node.id(), case_op_index));
                            }

                            // emit default
                            self.process_dest(&ops, default, f_content, f_context, vm);
                            
                            let default_target = f_content.get_block(default.target).name().unwrap();
                            self.backend.emit_jmp(default_target);
                        } else {
                            // other EQ-comparable types, e.g. floating point
                            unimplemented!()
                        }
                    }
                    
                    Instruction_::ExprCall{ref data, is_abort} => {
                        trace!("instsel on EXPRCALL");

                        if is_abort {
                            // if any exception throws from the callee,
                            // we should abort execution, otherwise rethrow the exception
                            // FIXME: implement is_abort
                            unimplemented!()
                        }
                        
                        self.emit_mu_call(
                            inst, // inst: &Instruction,
                            data, // calldata: &CallData,
                            None, // resumption: Option<&ResumptionData>,
                            node, // cur_node: &TreeNode, 
                            f_content, f_context, vm);
                    },
                    
                    Instruction_::Call{ref data, ref resume} => {
                        trace!("instsel on CALL");

                        self.emit_mu_call(
                            inst, 
                            data, 
                            Some(resume), 
                            node, 
                            f_content, f_context, vm);
                    },

                    Instruction_::ExprCCall{ref data, is_abort} => {
                        trace!("instsel on EXPRCCALL");

                        if is_abort {
                            // if any exception throws from the callee,
                            // we should abort execution, otherwise rethrow the exception
                            // FIXME: implement is_abort
                            unimplemented!()
                        }

                        self.emit_c_call_ir(
                            inst,
                            data,
                            None,
                            node,
                            f_content, f_context, vm);
                    }

                    Instruction_::CCall{ref data, ref resume} => {
                        trace!("instsel on CCALL");

                        self.emit_c_call_ir(
                            inst,
                            data,
                            Some(resume),
                            node,
                            f_content, f_context, vm);
                    }
                    
                    Instruction_::Return(_) => {
                        trace!("instsel on RETURN");

                        self.emit_common_epilogue(inst, f_content, f_context, vm);
                        
                        self.backend.emit_ret();
                    },
                    
                    Instruction_::BinOp(op, op1, op2) => {
                        trace!("instsel on BINOP");

                        self.emit_binop(node, inst, op, op1, op2, f_content, f_context, vm);
                    },

                    Instruction_::BinOpWithStatus(op, status, op1, op2) => {
                        trace!("instsel on BINOP_STATUS");

                        self.emit_binop(node, inst, op, op1, op2, f_content, f_context, vm);

                        let values = inst.value.as_ref().unwrap();
                        let mut status_value_index = 1;

                        // status flags only works with int operations
                        if RegGroup::get_from_value(&values[0]) == RegGroup::GPR {
                            // for mul, div, idiv, some of the flags may not generated
                            // from the computation, and we may need extra code
                            // to get the flags
                            // FIXME: See Issue#22

                            // negative flag
                            if status.flag_n {
                                let tmp_status = values[status_value_index].clone();
                                status_value_index += 1;

                                self.backend.emit_sets_r8(&tmp_status);
                            }

                            // zero flag
                            if status.flag_z {
                                let tmp_status = values[status_value_index].clone();
                                status_value_index += 1;

                                self.backend.emit_setz_r8(&tmp_status);
                            }

                            // unsigned overflow
                            if status.flag_c {
                                let tmp_status = values[status_value_index].clone();
                                status_value_index += 1;

                                match op {
                                    BinOp::Add | BinOp::Sub | BinOp::Mul => {
                                        self.backend.emit_setb_r8(&tmp_status);
                                    }
                                    _ => panic!("Only Add/Sub/Mul has #C flag")
                                }
                            }

                            // signed overflow
                            if status.flag_v {
                                let tmp_status = values[status_value_index].clone();

                                match op {
                                    BinOp::Add | BinOp::Sub | BinOp::Mul => {
                                        self.backend.emit_seto_r8(&tmp_status);
                                    }
                                    _ => panic!("Only Add/Sub/Mul has #V flag")
                                }
                            }
                        } else if RegGroup::get_from_value(&values[0]) == RegGroup::GPREX {
                            unimplemented!()
                        } else {
                            panic!("only int operations allow binop status flags")
                        }
                    }

                    Instruction_::ConvOp{operation, ref from_ty, ref to_ty, operand} => {
                        trace!("instsel on CONVOP");

                        let ref ops = inst.ops;
                        let ref op = ops[operand];

                        match operation {
                            // Truncate (from int to int)
                            op::ConvOp::TRUNC => {
                                let tmp_res = self.get_result_value(node);
                                let to_ty_size = vm.get_backend_type_size(tmp_res.ty.id());

                                if self.match_ireg(op) {
                                    let tmp_op = self.emit_ireg(op, f_content, f_context, vm);

                                    // mov op -> result
                                    match to_ty_size {
                                        1 => self.backend.emit_mov_r_r(&tmp_res, unsafe {&tmp_op.as_type(UINT8_TYPE.clone())}),
                                        2 => self.backend.emit_mov_r_r(&tmp_res, unsafe {&tmp_op.as_type(UINT16_TYPE.clone())}),
                                        4 => self.backend.emit_mov_r_r(&tmp_res, unsafe {&tmp_op.as_type(UINT32_TYPE.clone())}),
                                        8 => self.backend.emit_mov_r_r(&tmp_res, unsafe {&tmp_op.as_type(UINT64_TYPE.clone())}),
                                        _  => panic!("unsupported int size: {}", to_ty_size)
                                    }
                                } else if self.match_ireg_ex(op) {
                                    let (op_l, _) = self.emit_ireg_ex(op, f_content, f_context, vm);

                                    match to_ty_size {
                                        1 | 2 => self.backend.emit_movz_r_r(unsafe {&tmp_res.as_type(UINT32_TYPE.clone())}, &op_l),
                                        4 | 8 => self.backend.emit_mov_r_r(&tmp_res, &op_l),
                                        _ => panic!("unsupported int size: {}", to_ty_size)
                                    }
                                } else {
                                    panic!("unexpected op (expect ireg): {}", op);
                                }
                            }
                            // Zero extend (from int to int)
                            op::ConvOp::ZEXT => {
                                if self.match_ireg(op) {
                                    let tmp_op = self.emit_ireg(op, f_content, f_context, vm);
                                    let tmp_res = self.get_result_value(node);

                                    // movz op -> result
                                    let from_ty_size = vm.get_backend_type_size(from_ty.id());
                                    let to_ty_size   = vm.get_backend_type_size(to_ty.id());

                                    // we treat int1 as int8, so it is possible from_ty_size == to_ty_size == 1 byte
                                    assert!(from_ty_size <= to_ty_size);

                                    if from_ty_size != to_ty_size {
                                        match (from_ty_size, to_ty_size) {
                                            // int32 to int64
                                            (4, 8) => {
                                                // zero extend from 32 bits to 64 bits is a mov instruction
                                                // x86 does not have movzlq (32 to 64)

                                                // tmp_op is int32, but tmp_res is int64
                                                // we want to force a 32-to-32 mov, so high bits of the destination will be zeroed
                                                let tmp_res32 = unsafe {tmp_res.as_type(UINT32_TYPE.clone())};

                                                self.backend.emit_mov_r_r(&tmp_res32, &tmp_op);
                                            }
                                            // any int to int128
                                            (_, 16) => {
                                                let (res_l, res_h) = self.split_int128(&tmp_res, f_context, vm);

                                                self.backend.emit_mov_r_r(&res_l, unsafe {&tmp_op.as_type(UINT64_TYPE.clone())});
                                                self.backend.emit_mov_r_imm(&res_h, 0);
                                            }
                                            // other cases
                                            _ => {
                                                self.backend.emit_movz_r_r(&tmp_res, &tmp_op);
                                            }
                                        }
                                    } else {
                                        self.backend.emit_mov_r_r(&tmp_res, &tmp_op);
                                    }
                                } else {
                                    panic!("unexpected op (expect ireg): {}", op);
                                }
                            },
                            // Sign extend (from int to int)
                            op::ConvOp::SEXT => {
                                if self.match_ireg(op) {
                                    let tmp_op = self.emit_ireg(op, f_content, f_context, vm);
                                    let tmp_res = self.get_result_value(node);

                                    // movs op -> result
                                    let from_ty_size = vm.get_backend_type_size(from_ty.id());
                                    let to_ty_size   = vm.get_backend_type_size(to_ty.id());

                                    // we treat int1 as int8, so it is possible from_ty_size == to_ty_size == 1 byte
                                    assert!(from_ty_size <= to_ty_size);

                                    if from_ty_size != to_ty_size {
                                        match (from_ty_size, to_ty_size) {
                                            // int64 to int128
                                            (8, 16) => {
                                                let (res_l, res_h) = self.split_int128(&tmp_res, f_context, vm);

                                                // mov tmp_op -> res_h
                                                // sar res_h 63
                                                self.backend.emit_mov_r_r(&res_h, &tmp_op);
                                                self.backend.emit_sar_r_imm8(&res_h, 63i8);

                                                // mov tmp_op -> res_l
                                                self.backend.emit_mov_r_r(&res_l, &tmp_op);
                                            }
                                            // int32 to int128
                                            (_, 16) => {
                                                let (res_l, res_h) = self.split_int128(&tmp_res, f_context, vm);

                                                // movs tmp_op -> res_l
                                                self.backend.emit_movs_r_r(&res_l, &tmp_op);

                                                // mov res_l -> res_h
                                                // sar res_h 63
                                                self.backend.emit_mov_r_r(&res_h, unsafe {&res_l.as_type(UINT32_TYPE.clone())});
                                                self.backend.emit_sar_r_imm8(&res_h, 63i8);
                                            }
                                            _ => self.backend.emit_movs_r_r(&tmp_res, &tmp_op)
                                        }
                                    } else {
                                        // FIXME: sign extending <int1> 1 to <int8> is not a plain move
                                        self.backend.emit_mov_r_r(&tmp_res, &tmp_op);
                                    }
                                } else {
                                    panic!("unexpected op (expect ireg): {}", op)
                                }
                            }
                            // pointer/ref cast
                            op::ConvOp::REFCAST | op::ConvOp::PTRCAST => {
                                // just a mov (and hopefully reg alloc will coalesce it)
                                let tmp_res = self.get_result_value(node);

                                if self.match_ireg(op) {
                                    let tmp_op = self.emit_ireg(op, f_content, f_context, vm);
                                    self.backend.emit_mov_r_r(&tmp_res, &tmp_op);
                                } else {
                                    panic!("unexpected op (expect ireg): {}", op)
                                }
                            }
                            // signed integer to floating point
                            op::ConvOp::SITOFP => {
                                let tmp_res = self.get_result_value(node);

                                if self.match_ireg(op) {
                                    let tmp_op = self.emit_ireg(op, f_content, f_context, vm);
                                    match to_ty.v {
                                        MuType_::Double => self.backend.emit_cvtsi2sd_f64_r(&tmp_res, &tmp_op),
                                        MuType_::Float  => self.backend.emit_cvtsi2ss_f32_r(&tmp_res, &tmp_op),
                                        _ => panic!("expecting fp type as to type in SITOFP, found {}", to_ty)
                                    }
                                } else if self.match_ireg_ex(op) {
                                    unimplemented!()
                                } else {
                                    panic!("unexpected op (expect ireg/ireg_ex): {}", op)
                                }
                            }
                            // floating point to signed integer
                            op::ConvOp::FPTOSI => {
                                let tmp_res = self.get_result_value(node);

                                assert!(self.match_fpreg(op), "unexpected op (expected fpreg): {}", op);
                                let tmp_op = self.emit_fpreg(op, f_content, f_context, vm);

                                let to_ty_size   = vm.get_backend_type_size(to_ty.id());
                                match to_ty_size {
                                    1 | 2 | 4 | 8 => {
                                        match from_ty.v {
                                            MuType_::Double => self.backend.emit_cvtsd2si_r_f64(&tmp_res, &tmp_op),
                                            MuType_::Float  => self.backend.emit_cvtss2si_r_f32(&tmp_res, &tmp_op),
                                            _ => panic!("expected fp type as from type in FPTOSI, found {}", from_ty)
                                        }
                                    }
                                    16 => {
                                        unimplemented!()
                                    }
                                    _ => panic!("unexpected support integer type as to_type: {}", to_ty)
                                }

                            }
                            // unsigned integer to floating point
                            op::ConvOp::UITOFP => {
                                let tmp_res = self.get_result_value(node);

                                if self.match_ireg(op) {
                                    let tmp_op = self.emit_ireg(op, f_content, f_context, vm);

                                    let op_ty_size = vm.get_backend_type_size(tmp_op.ty.id());

                                    if to_ty.is_double() {
                                        match op_ty_size {
                                            8 => {
                                                // movd/movq op -> res
                                                self.backend.emit_mov_fpr_r64(&tmp_res, &tmp_op);

                                                // punpckldq UITOFP_C0, tmp_res -> tmp_res
                                                // (interleaving low bytes: xmm = xmm[0] mem[0] xmm[1] mem[1]
                                                let mem_c0 = self.get_mem_for_const(UITOFP_C0.clone(), vm);
                                                self.backend.emit_punpckldq_f64_mem128(&tmp_res, &mem_c0);

                                                // subpd UITOFP_C1, tmp_res -> tmp_res
                                                let mem_c1 = self.get_mem_for_const(UITOFP_C1.clone(), vm);
                                                self.backend.emit_subpd_f64_mem128(&tmp_res, &mem_c1);

                                                // haddpd tmp_res, tmp_res -> tmp_res
                                                self.backend.emit_haddpd_f64_f64(&tmp_res, &tmp_res);
                                            }
                                            4 => {
                                                let tmp = self.make_temporary(f_context, UINT64_TYPE.clone(), vm);

                                                // movl op -> tmp(32)
                                                let tmp32 = unsafe { tmp.as_type(UINT32_TYPE.clone()) };
                                                self.backend.emit_mov_r_r(&tmp32, &tmp_op);

                                                // cvtsi2sd %tmp(64) -> %tmp_res
                                                self.backend.emit_cvtsi2sd_f64_r(&tmp_res, &tmp);
                                            }
                                            2 | 1 => {
                                                let tmp_op32 = unsafe { tmp_op.as_type(UINT32_TYPE.clone()) };
                                                self.backend.emit_cvtsi2sd_f64_r(&tmp_res, &tmp_op32);
                                            }
                                            _ => panic!("not implemented int length {}", op_ty_size)
                                        }
                                    } else if to_ty.is_float() {
                                        match op_ty_size {
                                            8 => {
                                                // movl %tmp_op -> %tmp1
                                                let tmp1 = self.make_temporary(f_context, UINT32_TYPE.clone(), vm);
                                                self.backend.emit_mov_r_r(&tmp1, unsafe {&tmp_op.as_type(UINT32_TYPE.clone())});

                                                // andl %tmp1 $1 -> %tmp1
                                                self.backend.emit_and_r_imm(&tmp1, 1);

                                                // testq %tmp_op %tmp_op
                                                self.backend.emit_test_r_r(&tmp_op, &tmp_op);

                                                let blk_if_signed     = format!("{}_{}_uitofp_float_if_signed", self.current_fv_id, node.id());
                                                let blk_if_not_signed = format!("{}_{}_uitofp_float_if_not_signed", self.current_fv_id, node.id());
                                                let blk_done          = format!("{}_{}_uitofp_float_done", self.current_fv_id, node.id());

                                                // js %if_signed
                                                self.backend.emit_js(blk_if_signed.clone());
                                                self.finish_block();

                                                // blk_if_not_signed:
                                                self.start_block(blk_if_not_signed);

                                                // cvtsi2ss %tmp_op -> %tmp_res
                                                self.backend.emit_cvtsi2ss_f32_r(&tmp_res, &tmp_op);

                                                // jmp blk_done
                                                self.backend.emit_jmp(blk_done.clone());
                                                self.finish_block();

                                                // blk_if_signed:
                                                self.start_block(blk_if_signed);

                                                // shr %tmp_op $1 -> %tmp_op
                                                self.backend.emit_shr_r_imm8(&tmp_op, 1);

                                                // or %tmp_op %tmp1 -> %tmp1
                                                self.backend.emit_or_r_r(unsafe {&tmp1.as_type(UINT64_TYPE.clone())}, &tmp_op);

                                                // cvtsi2ss %tmp1 -> %tmp_res
                                                self.backend.emit_cvtsi2ss_f32_r(&tmp_res, &tmp1);