v86/src/rust/codegen.rs

use global_pointers;
use jit::JitContext;
use jit::{GEN_LOCAL_SCRATCH0, GEN_LOCAL_SCRATCH1, GEN_LOCAL_SCRATCH2};
use modrm;
use tlb::{TLB_GLOBAL, TLB_NO_USER, TLB_READONLY, TLB_VALID};
use wasmgen::module_init::WasmBuilder;
use wasmgen::{module_init, wasm_util};

pub fn gen_set_previous_eip_offset_from_eip(builder: &mut WasmBuilder, n: u32) {
    let cs = &mut builder.code_section;
    wasm_util::push_i32(cs, global_pointers::PREVIOUS_IP as i32); // store address of previous ip
    wasm_util::load_aligned_i32(cs, global_pointers::INSTRUCTION_POINTER); // load ip
    if n != 0 {
        wasm_util::push_i32(cs, n as i32);
        wasm_util::add_i32(cs); // add constant to ip value
    }
    wasm_util::store_aligned_i32(cs); // store it as previous ip
}

pub fn gen_increment_instruction_pointer(builder: &mut WasmBuilder, n: u32) {
    let cs = &mut builder.code_section;
    wasm_util::push_i32(cs, global_pointers::INSTRUCTION_POINTER as i32); // store address of ip

    wasm_util::load_aligned_i32(cs, global_pointers::INSTRUCTION_POINTER); // load ip

    wasm_util::push_i32(cs, n as i32);

    wasm_util::add_i32(cs);
    wasm_util::store_aligned_i32(cs); // store it back in
}

pub fn gen_set_previous_eip(builder: &mut WasmBuilder) {
    let cs = &mut builder.code_section;
    wasm_util::push_i32(cs, global_pointers::PREVIOUS_IP as i32); // store address of previous ip
    wasm_util::load_aligned_i32(cs, global_pointers::INSTRUCTION_POINTER); // load ip
    wasm_util::store_aligned_i32(cs); // store it as previous ip
}

pub fn gen_relative_jump(builder: &mut WasmBuilder, n: i32) {
    // add n to instruction_pointer (without setting the offset as above)
    let instruction_body = &mut builder.instruction_body;
    wasm_util::push_i32(
        instruction_body,
        global_pointers::INSTRUCTION_POINTER as i32,
    );
    wasm_util::load_aligned_i32(instruction_body, global_pointers::INSTRUCTION_POINTER);
    wasm_util::push_i32(instruction_body, n);
    wasm_util::add_i32(instruction_body);
    wasm_util::store_aligned_i32(instruction_body);
}

pub fn gen_increment_variable(builder: &mut WasmBuilder, variable_address: u32, n: i32) {
    wasm_util::increment_variable(&mut builder.code_section, variable_address, n);
}

pub fn gen_increment_timestamp_counter(builder: &mut WasmBuilder, n: i32) {
    gen_increment_variable(builder, global_pointers::TIMESTAMP_COUNTER, n);
}

pub fn gen_increment_mem32(builder: &mut WasmBuilder, addr: u32) {
    wasm_util::increment_mem32(&mut builder.code_section, addr)
}

pub fn gen_fn0_const(ctx: &mut JitContext, name: &str) {
    let builder = &mut ctx.builder;
    let fn_idx = builder.get_fn_idx(name, module_init::FN0_TYPE_INDEX);
    wasm_util::call_fn(&mut builder.instruction_body, fn_idx);
}

pub fn gen_fn0_const_ret(builder: &mut WasmBuilder, name: &str) {
    let fn_idx = builder.get_fn_idx(name, module_init::FN0_RET_TYPE_INDEX);
    wasm_util::call_fn(&mut builder.instruction_body, fn_idx);
}

pub fn gen_fn1_const(ctx: &mut JitContext, name: &str, arg0: u32) {
    let builder = &mut ctx.builder;
    let fn_idx = builder.get_fn_idx(name, module_init::FN1_TYPE_INDEX);
    wasm_util::push_i32(&mut builder.instruction_body, arg0 as i32);
    wasm_util::call_fn(&mut builder.instruction_body, fn_idx);
}

pub fn gen_call_fn1_ret(builder: &mut WasmBuilder, name: &str) {
    // generates: fn( _ ) where _ must be left on the stack before calling this, and fn returns a value
    let fn_idx = builder.get_fn_idx(name, module_init::FN1_RET_TYPE_INDEX);
    wasm_util::call_fn(&mut builder.instruction_body, fn_idx);
}

pub fn gen_fn2_const(ctx: &mut JitContext, name: &str, arg0: u32, arg1: u32) {
    let builder = &mut ctx.builder;
    let fn_idx = builder.get_fn_idx(name, module_init::FN2_TYPE_INDEX);
    wasm_util::push_i32(&mut builder.instruction_body, arg0 as i32);
    wasm_util::push_i32(&mut builder.instruction_body, arg1 as i32);
    wasm_util::call_fn(&mut builder.instruction_body, fn_idx);
}

pub fn gen_call_fn2(builder: &mut WasmBuilder, name: &str) {
    // generates: fn( _, _ ) where _ must be left on the stack before calling this
    let fn_idx = builder.get_fn_idx(name, module_init::FN2_TYPE_INDEX);
    wasm_util::call_fn(&mut builder.instruction_body, fn_idx);
}

pub fn gen_fn3_const(ctx: &mut JitContext, name: &str, arg0: u32, arg1: u32, arg2: u32) {
    let builder = &mut ctx.builder;
    let fn_idx = builder.get_fn_idx(name, module_init::FN3_TYPE_INDEX);
    wasm_util::push_i32(&mut builder.instruction_body, arg0 as i32);
    wasm_util::push_i32(&mut builder.instruction_body, arg1 as i32);
    wasm_util::push_i32(&mut builder.instruction_body, arg2 as i32);
    wasm_util::call_fn(&mut builder.instruction_body, fn_idx);
}

pub fn gen_modrm_fn0(ctx: &mut JitContext, name: &str) {
    // generates: fn( _ )
    let builder = &mut ctx.builder;
    let fn_idx = builder.get_fn_idx(name, module_init::FN1_TYPE_INDEX);
    wasm_util::call_fn(&mut builder.instruction_body, fn_idx);
}

pub fn gen_modrm_fn1(ctx: &mut JitContext, name: &str, arg0: u32) {
    // generates: fn( _, arg0 )
    let builder = &mut ctx.builder;
    let fn_idx = builder.get_fn_idx(name, module_init::FN2_TYPE_INDEX);
    wasm_util::push_i32(&mut builder.instruction_body, arg0 as i32);
    wasm_util::call_fn(&mut builder.instruction_body, fn_idx);
}

pub fn gen_modrm_fn2(ctx: &mut JitContext, name: &str, arg0: u32, arg1: u32) {
    // generates: fn( _, arg0, arg1 )
    let builder = &mut ctx.builder;
    let fn_idx = builder.get_fn_idx(name, module_init::FN3_TYPE_INDEX);
    wasm_util::push_i32(&mut builder.instruction_body, arg0 as i32);
    wasm_util::push_i32(&mut builder.instruction_body, arg1 as i32);
    wasm_util::call_fn(&mut builder.instruction_body, fn_idx);
}

pub fn gen_modrm_resolve(ctx: &mut JitContext, modrm_byte: u8) { modrm::gen(ctx, modrm_byte) }

pub fn gen_set_reg16_r(ctx: &mut JitContext, dest: u32, src: u32) {
    // generates: reg16[r_dest] = reg16[r_src]
    let builder = &mut ctx.builder;
    wasm_util::push_i32(
        &mut builder.instruction_body,
        global_pointers::get_reg16_offset(dest) as i32,
    );
    wasm_util::load_aligned_u16(
        &mut builder.instruction_body,
        global_pointers::get_reg16_offset(src),
    );
    wasm_util::store_aligned_u16(&mut builder.instruction_body);
}
pub fn gen_set_reg32_r(ctx: &mut JitContext, dest: u32, src: u32) {
    // generates: reg32s[r_dest] = reg32s[r_src]
    let builder = &mut ctx.builder;
    wasm_util::push_i32(
        &mut builder.instruction_body,
        global_pointers::get_reg32_offset(dest) as i32,
    );
    wasm_util::load_aligned_i32(
        &mut builder.instruction_body,
        global_pointers::get_reg32_offset(src),
    );
    wasm_util::store_aligned_i32(&mut builder.instruction_body);
}

pub fn gen_set_reg16_fn0(ctx: &mut JitContext, name: &str, reg: u32) {
    // generates: reg16[reg] = fn()
    let builder = &mut ctx.builder;
    let fn_idx = builder.get_fn_idx(name, module_init::FN0_RET_TYPE_INDEX);
    wasm_util::push_i32(
        &mut builder.instruction_body,
        global_pointers::get_reg16_offset(reg) as i32,
    );
    wasm_util::call_fn(&mut builder.instruction_body, fn_idx);
    wasm_util::store_aligned_u16(&mut builder.instruction_body);
}

pub fn gen_set_reg32s_fn0(ctx: &mut JitContext, name: &str, reg: u32) {
    // generates: reg32s[reg] = fn()
    let builder = &mut ctx.builder;
    let fn_idx = builder.get_fn_idx(name, module_init::FN0_RET_TYPE_INDEX);
    wasm_util::push_i32(
        &mut builder.instruction_body,
        global_pointers::get_reg32_offset(reg) as i32,
    );
    wasm_util::call_fn(&mut builder.instruction_body, fn_idx);
    wasm_util::store_aligned_i32(&mut builder.instruction_body);
}

pub fn gen_safe_read32(ctx: &mut JitContext) {
    // Assumes virtual address has been pushed to the stack, and generates safe_read32s' fast-path
    // inline, bailing to safe_read32s_slow if necessary
    let builder = &mut ctx.builder;
    //let instruction_body = &mut ctx.builder.instruction_body;
    //let cpu = &mut ctx.cpu;

    let address_local = GEN_LOCAL_SCRATCH0;
    wasm_util::tee_local(&mut builder.instruction_body, address_local);

    // Pseudo: base_on_stack = (uint32_t)address >> 12;
    wasm_util::push_i32(&mut builder.instruction_body, 12);
    wasm_util::shr_u32(&mut builder.instruction_body);

    // scale index
    wasm_util::push_i32(&mut builder.instruction_body, 2);
    wasm_util::shl_i32(&mut builder.instruction_body);

    // Pseudo: entry = tlb_data[base_on_stack];
    let entry_local = GEN_LOCAL_SCRATCH1;
    wasm_util::load_aligned_i32_from_stack(
        &mut builder.instruction_body,
        global_pointers::TLB_DATA,
    );
    wasm_util::tee_local(&mut builder.instruction_body, entry_local);

    // Pseudo: bool can_use_fast_path = (entry & 0xFFF & ~TLB_READONLY & ~TLB_GLOBAL & ~(cpl == 3 ? 0 : TLB_NO_USER) == TLB_VALID &&
    //                                   (address & 0xFFF) <= (0x1000 - 4));
    wasm_util::push_i32(
        &mut builder.instruction_body,
        (0xFFF & !TLB_READONLY & !TLB_GLOBAL & !(if ctx.cpu.cpl3() { 0 } else { TLB_NO_USER }))
            as i32,
    );
    wasm_util::and_i32(&mut builder.instruction_body);

    wasm_util::push_i32(&mut builder.instruction_body, TLB_VALID as i32);
    wasm_util::eq_i32(&mut builder.instruction_body);

    wasm_util::get_local(&mut builder.instruction_body, address_local);
    wasm_util::push_i32(&mut builder.instruction_body, 0xFFF);
    wasm_util::and_i32(&mut builder.instruction_body);
    wasm_util::push_i32(&mut builder.instruction_body, 0x1000 - 4);
    wasm_util::le_i32(&mut builder.instruction_body);

    wasm_util::and_i32(&mut builder.instruction_body);

    // Pseudo:
    // if(can_use_fast_path) leave_on_stack(mem8[entry & ~0xFFF ^ address]);
    wasm_util::if_i32(&mut builder.instruction_body);
    wasm_util::get_local(&mut builder.instruction_body, entry_local);
    wasm_util::push_i32(&mut builder.instruction_body, !0xFFF);
    wasm_util::and_i32(&mut builder.instruction_body);
    wasm_util::get_local(&mut builder.instruction_body, address_local);
    wasm_util::xor_i32(&mut builder.instruction_body);

    wasm_util::load_unaligned_i32_from_stack(
        &mut builder.instruction_body,
        global_pointers::MEMORY,
    );

    // Pseudo:
    // else { leave_on_stack(safe_read32s_slow(address)); }
    wasm_util::else_(&mut builder.instruction_body);
    wasm_util::get_local(&mut builder.instruction_body, address_local);
    gen_call_fn1_ret(builder, "safe_read32s_slow");
    wasm_util::block_end(&mut builder.instruction_body);
}

pub fn gen_safe_write32(ctx: &mut JitContext, local_for_address: u32, local_for_value: u32) {
    // Generates safe_write32' fast-path inline, bailing to safe_write32_slow if necessary.

    // local_for_{address,value} are the numbers of the local variables which contain the virtual
    // address and value for safe_write32
    // Usage:
    // set_local(0, value);
    // set_local(1, v_addr);
    // gen_safe_write32(0, 1);

    // Since this function clobbers other variables, we confirm that the caller uses the local
    // variables we expect them to
    assert!(local_for_address == GEN_LOCAL_SCRATCH0);
    assert!(local_for_value == GEN_LOCAL_SCRATCH1);

    let builder = &mut ctx.builder;
    //let instruction_body = &mut ctx.builder.instruction_body;
    //let cpu = &mut ctx.cpu;

    wasm_util::get_local(&mut builder.instruction_body, local_for_address);

    // Pseudo: base_on_stack = (uint32_t)address >> 12;
    wasm_util::push_i32(&mut builder.instruction_body, 12);
    wasm_util::shr_u32(&mut builder.instruction_body);

    // scale index
    wasm_util::push_i32(&mut builder.instruction_body, 2);
    wasm_util::shl_i32(&mut builder.instruction_body);

    // entry_local is only used in the following block, so the scratch variable can be reused later
    {
        // Pseudo: entry = tlb_data[base_on_stack];
        let entry_local = GEN_LOCAL_SCRATCH2;
        wasm_util::load_aligned_i32_from_stack(
            &mut builder.instruction_body,
            global_pointers::TLB_DATA,
        );
        wasm_util::tee_local(&mut builder.instruction_body, entry_local);

        // Pseudo: bool can_use_fast_path = (entry & 0xFFF & ~TLB_GLOBAL & ~(cpl == 3 ? 0 : TLB_NO_USER) == TLB_VALID &&
        //                                   (address & 0xFFF) <= (0x1000 - 4));
        wasm_util::push_i32(
            &mut builder.instruction_body,
            (0xFFF & !TLB_GLOBAL & !(if ctx.cpu.cpl3() { 0 } else { TLB_NO_USER })) as i32,
        );
        wasm_util::and_i32(&mut builder.instruction_body);

        wasm_util::push_i32(&mut builder.instruction_body, TLB_VALID as i32);
        wasm_util::eq_i32(&mut builder.instruction_body);

        wasm_util::get_local(&mut builder.instruction_body, local_for_address);
        wasm_util::push_i32(&mut builder.instruction_body, 0xFFF);
        wasm_util::and_i32(&mut builder.instruction_body);
        wasm_util::push_i32(&mut builder.instruction_body, 0x1000 - 4);
        wasm_util::le_i32(&mut builder.instruction_body);

        wasm_util::and_i32(&mut builder.instruction_body);

        // Pseudo:
        // if(can_use_fast_path)
        // {
        //     phys_addr = entry & ~0xFFF ^ address;
        wasm_util::if_void(&mut builder.instruction_body);

        wasm_util::get_local(&mut builder.instruction_body, entry_local);
        wasm_util::push_i32(&mut builder.instruction_body, !0xFFF);
        wasm_util::and_i32(&mut builder.instruction_body);
        wasm_util::get_local(&mut builder.instruction_body, local_for_address);
        wasm_util::xor_i32(&mut builder.instruction_body);
    }

    // entry_local isn't needed anymore, so we overwrite it
    let phys_addr_local = GEN_LOCAL_SCRATCH2;
    // Pseudo:
    //     /* continued within can_use_fast_path branch */
    //     mem8[phys_addr] = value;

    wasm_util::tee_local(&mut builder.instruction_body, phys_addr_local);
    wasm_util::get_local(&mut builder.instruction_body, local_for_value);
    wasm_util::store_unaligned_i32(&mut builder.instruction_body, global_pointers::MEMORY);

    // Pseudo:
    // else { safe_read32_slow(address, value); }
    wasm_util::else_(&mut builder.instruction_body);
    wasm_util::get_local(&mut builder.instruction_body, local_for_address);
    wasm_util::get_local(&mut builder.instruction_body, local_for_value);
    gen_call_fn2(builder, "safe_write32_slow");
    wasm_util::block_end(&mut builder.instruction_body);
}

pub fn gen_fn1_reg16(ctx: &mut JitContext, name: &str, r: u32) {
    let fn_idx = ctx.builder.get_fn_idx(name, module_init::FN1_TYPE_INDEX);
    wasm_util::load_aligned_u16(
        &mut ctx.builder.instruction_body,
        global_pointers::get_reg16_offset(r),
    );
    wasm_util::call_fn(&mut ctx.builder.instruction_body, fn_idx)
}

pub fn gen_fn1_reg32(ctx: &mut JitContext, name: &str, r: u32) {
    let fn_idx = ctx.builder.get_fn_idx(name, module_init::FN1_TYPE_INDEX);
    wasm_util::load_aligned_i32(
        &mut ctx.builder.instruction_body,
        global_pointers::get_reg32_offset(r),
    );
    wasm_util::call_fn(&mut ctx.builder.instruction_body, fn_idx)
}

pub fn gen_clear_prefixes(ctx: &mut JitContext) {
    let instruction_body = &mut ctx.builder.instruction_body;
    wasm_util::push_i32(instruction_body, global_pointers::PREFIXES as i32); // load address of prefixes
    wasm_util::push_i32(instruction_body, 0);
    wasm_util::store_aligned_i32(instruction_body);
}

pub fn gen_add_prefix_bits(ctx: &mut JitContext, mask: u32) {
    assert!(mask < 0x100);

    let instruction_body = &mut ctx.builder.instruction_body;
    wasm_util::push_i32(instruction_body, global_pointers::PREFIXES as i32); // load address of prefixes

    wasm_util::load_aligned_i32(instruction_body, global_pointers::PREFIXES); // load old value
    wasm_util::push_i32(instruction_body, mask as i32);
    wasm_util::or_i32(instruction_body);

    wasm_util::store_aligned_i32(instruction_body);
}