Archipelago » qemu

/*

 * Optimizations for Tiny Code Generator for QEMU

 *

 * Copyright (c) 2010 Samsung Electronics.

 * Contributed by Kirill Batuzov <batuzovk@ispras.ru>

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL

 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

 * THE SOFTWARE.

 */

#include "config.h"

#include <stdlib.h>

#include <stdio.h>

#include "qemu-common.h"

#include "tcg-op.h"

#define CASE_OP_32_64(x)                        \

        glue(glue(case INDEX_op_, x), _i32):    \

        glue(glue(case INDEX_op_, x), _i64)

typedef enum {

    TCG_TEMP_UNDEF = 0,

    TCG_TEMP_CONST,

    TCG_TEMP_COPY,

} tcg_temp_state;

struct tcg_temp_info {

    tcg_temp_state state;

    uint16_t prev_copy;

    uint16_t next_copy;

    tcg_target_ulong val;

};

static struct tcg_temp_info temps[TCG_MAX_TEMPS];

/* Reset TEMP's state to TCG_TEMP_UNDEF.  If TEMP only had one copy, remove

   the copy flag from the left temp.  */

static void reset_temp(TCGArg temp)

{

    if (temps[temp].state == TCG_TEMP_COPY) {

        if (temps[temp].prev_copy == temps[temp].next_copy) {

            temps[temps[temp].next_copy].state = TCG_TEMP_UNDEF;

        } else {

            temps[temps[temp].next_copy].prev_copy = temps[temp].prev_copy;

            temps[temps[temp].prev_copy].next_copy = temps[temp].next_copy;

        }

    }

    temps[temp].state = TCG_TEMP_UNDEF;

}

static int op_bits(TCGOpcode op)

{

    const TCGOpDef *def = &tcg_op_defs[op];

    return def->flags & TCG_OPF_64BIT ? 64 : 32;

}

static TCGOpcode op_to_movi(TCGOpcode op)

{

    switch (op_bits(op)) {

    case 32:

        return INDEX_op_movi_i32;

    case 64:

        return INDEX_op_movi_i64;

    default:

        fprintf(stderr, "op_to_movi: unexpected return value of "

                "function op_bits.\n");

        tcg_abort();

    }

}

static TCGArg find_better_copy(TCGContext *s, TCGArg temp)

{

    TCGArg i;

    /* If this is already a global, we can't do better. */

    if (temp < s->nb_globals) {

        return temp;

    }

    /* Search for a global first. */

    for (i = temps[temp].next_copy ; i != temp ; i = temps[i].next_copy) {

        if (i < s->nb_globals) {

            return i;

        }

    }

    /* If it is a temp, search for a temp local. */

    if (!s->temps[temp].temp_local) {

        for (i = temps[temp].next_copy ; i != temp ; i = temps[i].next_copy) {

            if (s->temps[i].temp_local) {

                return i;

            }

        }

    }

    /* Failure to find a better representation, return the same temp. */

    return temp;

}

static bool temps_are_copies(TCGArg arg1, TCGArg arg2)

{

    TCGArg i;

    if (arg1 == arg2) {

        return true;

    }

    if (temps[arg1].state != TCG_TEMP_COPY

        || temps[arg2].state != TCG_TEMP_COPY) {

        return false;

    }

    for (i = temps[arg1].next_copy ; i != arg1 ; i = temps[i].next_copy) {

        if (i == arg2) {

            return true;

        }

    }

    return false;

}

static void tcg_opt_gen_mov(TCGContext *s, TCGArg *gen_args,

                            TCGArg dst, TCGArg src)

{

        reset_temp(dst);

        assert(temps[src].state != TCG_TEMP_CONST);

        if (s->temps[src].type == s->temps[dst].type) {

            if (temps[src].state != TCG_TEMP_COPY) {

                temps[src].state = TCG_TEMP_COPY;

                temps[src].next_copy = src;

                temps[src].prev_copy = src;

            }

            temps[dst].state = TCG_TEMP_COPY;

            temps[dst].next_copy = temps[src].next_copy;

            temps[dst].prev_copy = src;

            temps[temps[dst].next_copy].prev_copy = dst;

            temps[src].next_copy = dst;

        }

        gen_args[0] = dst;

        gen_args[1] = src;

}

static void tcg_opt_gen_movi(TCGArg *gen_args, TCGArg dst, TCGArg val)

{

        reset_temp(dst);

        temps[dst].state = TCG_TEMP_CONST;

        temps[dst].val = val;

        gen_args[0] = dst;

        gen_args[1] = val;

}

static TCGOpcode op_to_mov(TCGOpcode op)

{

    switch (op_bits(op)) {

    case 32:

        return INDEX_op_mov_i32;

    case 64:

        return INDEX_op_mov_i64;

    default:

        fprintf(stderr, "op_to_mov: unexpected return value of "

                "function op_bits.\n");

        tcg_abort();

    }

}

static TCGArg do_constant_folding_2(TCGOpcode op, TCGArg x, TCGArg y)

{

    switch (op) {

    CASE_OP_32_64(add):

        return x + y;

    CASE_OP_32_64(sub):

        return x - y;

    CASE_OP_32_64(mul):

        return x * y;

    CASE_OP_32_64(and):

        return x & y;

    CASE_OP_32_64(or):

        return x | y;

    CASE_OP_32_64(xor):

        return x ^ y;

    case INDEX_op_shl_i32:

        return (uint32_t)x << (uint32_t)y;

    case INDEX_op_shl_i64:

        return (uint64_t)x << (uint64_t)y;

    case INDEX_op_shr_i32:

        return (uint32_t)x >> (uint32_t)y;

    case INDEX_op_shr_i64:

        return (uint64_t)x >> (uint64_t)y;

    case INDEX_op_sar_i32:

        return (int32_t)x >> (int32_t)y;

    case INDEX_op_sar_i64:

        return (int64_t)x >> (int64_t)y;

    case INDEX_op_rotr_i32:

        x = ((uint32_t)x << (32 - y)) | ((uint32_t)x >> y);

        return x;

    case INDEX_op_rotr_i64:

        x = ((uint64_t)x << (64 - y)) | ((uint64_t)x >> y);

        return x;

    case INDEX_op_rotl_i32:

        x = ((uint32_t)x << y) | ((uint32_t)x >> (32 - y));

        return x;

    case INDEX_op_rotl_i64:

        x = ((uint64_t)x << y) | ((uint64_t)x >> (64 - y));

        return x;

    CASE_OP_32_64(not):

        return ~x;

    CASE_OP_32_64(neg):

        return -x;

    CASE_OP_32_64(andc):

        return x & ~y;

    CASE_OP_32_64(orc):

        return x | ~y;

    CASE_OP_32_64(eqv):

        return ~(x ^ y);

    CASE_OP_32_64(nand):

        return ~(x & y);

    CASE_OP_32_64(nor):

        return ~(x | y);

    CASE_OP_32_64(ext8s):

        return (int8_t)x;

    CASE_OP_32_64(ext16s):

        return (int16_t)x;

    CASE_OP_32_64(ext8u):

        return (uint8_t)x;

    CASE_OP_32_64(ext16u):

        return (uint16_t)x;

    case INDEX_op_ext32s_i64:

        return (int32_t)x;

    case INDEX_op_ext32u_i64:

        return (uint32_t)x;

    default:

        fprintf(stderr,

                "Unrecognized operation %d in do_constant_folding.\n", op);

        tcg_abort();

    }

}

static TCGArg do_constant_folding(TCGOpcode op, TCGArg x, TCGArg y)

{

    TCGArg res = do_constant_folding_2(op, x, y);

    if (op_bits(op) == 32) {

        res &= 0xffffffff;

    }

    return res;

}

static TCGArg do_constant_folding_cond(TCGOpcode op, TCGArg x,

                                       TCGArg y, TCGCond c)

{

    switch (op_bits(op)) {

    case 32:

        switch (c) {

        case TCG_COND_EQ:

            return (uint32_t)x == (uint32_t)y;

        case TCG_COND_NE:

            return (uint32_t)x != (uint32_t)y;

        case TCG_COND_LT:

            return (int32_t)x < (int32_t)y;

        case TCG_COND_GE:

            return (int32_t)x >= (int32_t)y;

        case TCG_COND_LE:

            return (int32_t)x <= (int32_t)y;

        case TCG_COND_GT:

            return (int32_t)x > (int32_t)y;

        case TCG_COND_LTU:

            return (uint32_t)x < (uint32_t)y;

        case TCG_COND_GEU:

            return (uint32_t)x >= (uint32_t)y;

        case TCG_COND_LEU:

            return (uint32_t)x <= (uint32_t)y;

        case TCG_COND_GTU:

            return (uint32_t)x > (uint32_t)y;

        }

        break;

    case 64:

        switch (c) {

        case TCG_COND_EQ:

            return (uint64_t)x == (uint64_t)y;

        case TCG_COND_NE:

            return (uint64_t)x != (uint64_t)y;

        case TCG_COND_LT:

            return (int64_t)x < (int64_t)y;

        case TCG_COND_GE:

            return (int64_t)x >= (int64_t)y;

        case TCG_COND_LE:

            return (int64_t)x <= (int64_t)y;

        case TCG_COND_GT:

            return (int64_t)x > (int64_t)y;

        case TCG_COND_LTU:

            return (uint64_t)x < (uint64_t)y;

        case TCG_COND_GEU:

            return (uint64_t)x >= (uint64_t)y;

        case TCG_COND_LEU:

            return (uint64_t)x <= (uint64_t)y;

        case TCG_COND_GTU:

            return (uint64_t)x > (uint64_t)y;

        }

        break;

    }

    fprintf(stderr,

            "Unrecognized bitness %d or condition %d in "

            "do_constant_folding_cond.\n", op_bits(op), c);

    tcg_abort();

}

/* Propagate constants and copies, fold constant expressions. */

static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,

                                    TCGArg *args, TCGOpDef *tcg_op_defs)

{

    int i, nb_ops, op_index, nb_temps, nb_globals, nb_call_args;

    TCGOpcode op;

    const TCGOpDef *def;

    TCGArg *gen_args;

    TCGArg tmp;

    TCGCond cond;

    /* Array VALS has an element for each temp.

       If this temp holds a constant then its value is kept in VALS' element.

       If this temp is a copy of other ones then the other copies are

       available through the doubly linked circular list. */

    nb_temps = s->nb_temps;

    nb_globals = s->nb_globals;

    memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));

    nb_ops = tcg_opc_ptr - gen_opc_buf;

    gen_args = args;

    for (op_index = 0; op_index < nb_ops; op_index++) {

        op = gen_opc_buf[op_index];

        def = &tcg_op_defs[op];

        /* Do copy propagation */

        if (!(def->flags & (TCG_OPF_CALL_CLOBBER | TCG_OPF_SIDE_EFFECTS))) {

            assert(op != INDEX_op_call);

            for (i = def->nb_oargs; i < def->nb_oargs + def->nb_iargs; i++) {

                if (temps[args[i]].state == TCG_TEMP_COPY) {

                    args[i] = find_better_copy(s, args[i]);

                }

            }

        }

        /* For commutative operations make constant second argument */

        switch (op) {

        CASE_OP_32_64(add):

        CASE_OP_32_64(mul):

        CASE_OP_32_64(and):

        CASE_OP_32_64(or):

        CASE_OP_32_64(xor):

        CASE_OP_32_64(eqv):

        CASE_OP_32_64(nand):

        CASE_OP_32_64(nor):

            if (temps[args[1]].state == TCG_TEMP_CONST) {

                tmp = args[1];

                args[1] = args[2];

                args[2] = tmp;

            }

            break;

        CASE_OP_32_64(brcond):

            if (temps[args[0]].state == TCG_TEMP_CONST

                && temps[args[1]].state != TCG_TEMP_CONST) {

                tmp = args[0];

                args[0] = args[1];

                args[1] = tmp;

                args[2] = tcg_swap_cond(args[2]);

            }

            break;

        CASE_OP_32_64(setcond):

            if (temps[args[1]].state == TCG_TEMP_CONST

                && temps[args[2]].state != TCG_TEMP_CONST) {

                tmp = args[1];

                args[1] = args[2];

                args[2] = tmp;

                args[3] = tcg_swap_cond(args[3]);

            }

            break;

        CASE_OP_32_64(movcond):

            cond = args[5];

            if (temps[args[1]].state == TCG_TEMP_CONST

                && temps[args[2]].state != TCG_TEMP_CONST) {

                tmp = args[1];

                args[1] = args[2];

                args[2] = tmp;

                cond = tcg_swap_cond(cond);

            }

            /* For movcond, we canonicalize the "false" input reg to match

               the destination reg so that the tcg backend can implement

               a "move if true" operation.  */

            if (args[0] == args[3]) {

                tmp = args[3];

                args[3] = args[4];

                args[4] = tmp;

                cond = tcg_invert_cond(cond);

            }

            args[5] = cond;

        default:

            break;

        }

        /* Simplify expressions for "shift/rot r, 0, a => movi r, 0" */

        switch (op) {

        CASE_OP_32_64(shl):

        CASE_OP_32_64(shr):

        CASE_OP_32_64(sar):

        CASE_OP_32_64(rotl):

        CASE_OP_32_64(rotr):

            if (temps[args[1]].state == TCG_TEMP_CONST

                && temps[args[1]].val == 0) {

                gen_opc_buf[op_index] = op_to_movi(op);

                tcg_opt_gen_movi(gen_args, args[0], 0);

                args += 3;

                gen_args += 2;

                continue;

            }

            break;

        default:

            break;

        }

        /* Simplify expression for "op r, a, 0 => mov r, a" cases */

        switch (op) {

        CASE_OP_32_64(add):

        CASE_OP_32_64(sub):

        CASE_OP_32_64(shl):

        CASE_OP_32_64(shr):

        CASE_OP_32_64(sar):

        CASE_OP_32_64(rotl):

        CASE_OP_32_64(rotr):

        CASE_OP_32_64(or):

        CASE_OP_32_64(xor):

            if (temps[args[1]].state == TCG_TEMP_CONST) {

                /* Proceed with possible constant folding. */

                break;

            }

            if (temps[args[2]].state == TCG_TEMP_CONST

                && temps[args[2]].val == 0) {

                if (temps_are_copies(args[0], args[1])) {

                    gen_opc_buf[op_index] = INDEX_op_nop;

                } else {

                    gen_opc_buf[op_index] = op_to_mov(op);

                    tcg_opt_gen_mov(s, gen_args, args[0], args[1]);

                    gen_args += 2;

                }

                args += 3;

                continue;

            }

            break;

        default:

            break;

        }

        /* Simplify expression for "op r, a, 0 => movi r, 0" cases */

        switch (op) {

        CASE_OP_32_64(and):

        CASE_OP_32_64(mul):

            if ((temps[args[2]].state == TCG_TEMP_CONST

                && temps[args[2]].val == 0)) {

                gen_opc_buf[op_index] = op_to_movi(op);

                tcg_opt_gen_movi(gen_args, args[0], 0);

                args += 3;

                gen_args += 2;

                continue;

            }

            break;

        default:

            break;

        }

        /* Simplify expression for "op r, a, a => mov r, a" cases */

        switch (op) {

        CASE_OP_32_64(or):

        CASE_OP_32_64(and):

            if (args[1] == args[2]) {

                if (temps_are_copies(args[0], args[1])) {

                    gen_opc_buf[op_index] = INDEX_op_nop;

                } else {

                    gen_opc_buf[op_index] = op_to_mov(op);

                    tcg_opt_gen_mov(s, gen_args, args[0], args[1]);

                    gen_args += 2;

                }

                args += 3;

                continue;

            }

            break;

        default:

            break;

        }

        /* Propagate constants through copy operations and do constant

           folding.  Constants will be substituted to arguments by register

           allocator where needed and possible.  Also detect copies. */

        switch (op) {

        CASE_OP_32_64(mov):

            if (temps_are_copies(args[0], args[1])) {

                args += 2;

                gen_opc_buf[op_index] = INDEX_op_nop;

                break;

            }

            if (temps[args[1]].state != TCG_TEMP_CONST) {

                tcg_opt_gen_mov(s, gen_args, args[0], args[1]);

                gen_args += 2;

                args += 2;

                break;

            }

            /* Source argument is constant.  Rewrite the operation and

               let movi case handle it. */

            op = op_to_movi(op);

            gen_opc_buf[op_index] = op;

            args[1] = temps[args[1]].val;

            /* fallthrough */

        CASE_OP_32_64(movi):

            tcg_opt_gen_movi(gen_args, args[0], args[1]);

            gen_args += 2;

            args += 2;

            break;

        CASE_OP_32_64(not):

        CASE_OP_32_64(neg):

        CASE_OP_32_64(ext8s):

        CASE_OP_32_64(ext8u):

        CASE_OP_32_64(ext16s):

        CASE_OP_32_64(ext16u):

        case INDEX_op_ext32s_i64:

        case INDEX_op_ext32u_i64:

            if (temps[args[1]].state == TCG_TEMP_CONST) {

                gen_opc_buf[op_index] = op_to_movi(op);

                tmp = do_constant_folding(op, temps[args[1]].val, 0);

                tcg_opt_gen_movi(gen_args, args[0], tmp);

            } else {

                reset_temp(args[0]);

                gen_args[0] = args[0];

                gen_args[1] = args[1];

            }

            gen_args += 2;

            args += 2;

            break;

        CASE_OP_32_64(add):

        CASE_OP_32_64(sub):

        CASE_OP_32_64(mul):

        CASE_OP_32_64(or):

        CASE_OP_32_64(and):

        CASE_OP_32_64(xor):

        CASE_OP_32_64(shl):

        CASE_OP_32_64(shr):

        CASE_OP_32_64(sar):

        CASE_OP_32_64(rotl):

        CASE_OP_32_64(rotr):

        CASE_OP_32_64(andc):

        CASE_OP_32_64(orc):

        CASE_OP_32_64(eqv):

        CASE_OP_32_64(nand):

        CASE_OP_32_64(nor):

            if (temps[args[1]].state == TCG_TEMP_CONST

                && temps[args[2]].state == TCG_TEMP_CONST) {

                gen_opc_buf[op_index] = op_to_movi(op);

                tmp = do_constant_folding(op, temps[args[1]].val,

                                          temps[args[2]].val);

                tcg_opt_gen_movi(gen_args, args[0], tmp);

                gen_args += 2;

            } else {

                reset_temp(args[0]);

                gen_args[0] = args[0];

                gen_args[1] = args[1];

                gen_args[2] = args[2];

                gen_args += 3;

            }

            args += 3;

            break;

        CASE_OP_32_64(setcond):

            if (temps[args[1]].state == TCG_TEMP_CONST

                && temps[args[2]].state == TCG_TEMP_CONST) {

                gen_opc_buf[op_index] = op_to_movi(op);

                tmp = do_constant_folding_cond(op, temps[args[1]].val,

                                               temps[args[2]].val, args[3]);

                tcg_opt_gen_movi(gen_args, args[0], tmp);

                gen_args += 2;

            } else {

                reset_temp(args[0]);

                gen_args[0] = args[0];

                gen_args[1] = args[1];

                gen_args[2] = args[2];

                gen_args[3] = args[3];

                gen_args += 4;

            }

            args += 4;

            break;

        CASE_OP_32_64(brcond):

            if (temps[args[0]].state == TCG_TEMP_CONST

                && temps[args[1]].state == TCG_TEMP_CONST) {

                if (do_constant_folding_cond(op, temps[args[0]].val,

                                             temps[args[1]].val, args[2])) {

                    memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));

                    gen_opc_buf[op_index] = INDEX_op_br;

                    gen_args[0] = args[3];

                    gen_args += 1;

                } else {

                    gen_opc_buf[op_index] = INDEX_op_nop;

                }

            } else {

                memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));

                reset_temp(args[0]);

                gen_args[0] = args[0];

                gen_args[1] = args[1];

                gen_args[2] = args[2];

                gen_args[3] = args[3];

                gen_args += 4;

            }

            args += 4;

            break;

        CASE_OP_32_64(movcond):

            if (temps[args[1]].state == TCG_TEMP_CONST

                && temps[args[2]].state == TCG_TEMP_CONST) {

                tmp = do_constant_folding_cond(op, temps[args[1]].val,

                                               temps[args[2]].val, args[5]);

                if (temps_are_copies(args[0], args[4-tmp])) {

                    gen_opc_buf[op_index] = INDEX_op_nop;

                } else if (temps[args[4-tmp]].state == TCG_TEMP_CONST) {

                    gen_opc_buf[op_index] = op_to_movi(op);

                    tcg_opt_gen_movi(gen_args, args[0], temps[args[4-tmp]].val);

                    gen_args += 2;

                } else {

                    gen_opc_buf[op_index] = op_to_mov(op);

                    tcg_opt_gen_mov(s, gen_args, args[0], args[4-tmp]);

                    gen_args += 2;

                }

            } else {

                reset_temp(args[0]);

                gen_args[0] = args[0];

                gen_args[1] = args[1];

                gen_args[2] = args[2];

                gen_args[3] = args[3];

                gen_args[4] = args[4];

                gen_args[5] = args[5];

                gen_args += 6;

            }

            args += 6;

            break;

        case INDEX_op_call:

            nb_call_args = (args[0] >> 16) + (args[0] & 0xffff);

            if (!(args[nb_call_args + 1] & (TCG_CALL_CONST | TCG_CALL_PURE))) {

                for (i = 0; i < nb_globals; i++) {

                    reset_temp(i);

                }

            }

            for (i = 0; i < (args[0] >> 16); i++) {

                reset_temp(args[i + 1]);

            }

            i = nb_call_args + 3;

            while (i) {

                *gen_args = *args;

                args++;

                gen_args++;

                i--;

            }

            break;

        default:

            /* Default case: we do know nothing about operation so no

               propagation is done.  We trash everything if the operation

               is the end of a basic block, otherwise we only trash the

               output args.  */

            if (def->flags & TCG_OPF_BB_END) {

                memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));

            } else {

                for (i = 0; i < def->nb_oargs; i++) {

                    reset_temp(args[i]);

                }

            }

            for (i = 0; i < def->nb_args; i++) {

                gen_args[i] = args[i];

            }

            args += def->nb_args;

            gen_args += def->nb_args;

            break;

        }

    }

    return gen_args;

}

TCGArg *tcg_optimize(TCGContext *s, uint16_t *tcg_opc_ptr,

        TCGArg *args, TCGOpDef *tcg_op_defs)

{

    TCGArg *res;

    res = tcg_constant_folding(s, tcg_opc_ptr, args, tcg_op_defs);

    return res;

}