MWCC/compiler_and_linker/unsorted/ValueNumbering.c

#include "compiler/ValueNumbering.h"
#include "compiler/Alias.h"
#include "compiler/PCode.h"
#include "compiler/Registers.h"
#include "compiler/RegisterInfo.h"
#include "compiler/CompilerTools.h"
#include "compiler/CError.h"

typedef struct ValueLabel {
    struct ValueLabel *next;
    PCodeArg op;
} ValueLabel;

typedef struct AvailableValue {
    struct AvailableValue *next;
    ValueLabel *labelled;
    PCode *pcode;
    int killedregister;
    int aliasnumber;
    int opnumbers[0];
} AvailableValue;

typedef struct RegValue {
    int number;
    int x4;
    AvailableValue *available;
} RegValue;

typedef struct State {
    void *stackedvalues;
    int valueceiling;
} State;

typedef struct StackedValue {
    struct StackedValue *next;
    PCodeArg op;
    RegValue value;
    Alias *alias;
    PCode *valuepcode;
} StackedValue;

int removedcommonsubexpressions;
int nextvaluenumber;
static AvailableValue *opvalue[428];
static RegValue *regvalue[RegClassMax];
static StackedValue *stackedvalues;
static int valueceiling;
static int moreaggressiveoptimization;

static void allocatecsedatastructures(void) {
    char rclass;

    for (rclass = 0; rclass < RegClassMax; rclass++)
        regvalue[(char) rclass] = oalloc(sizeof(RegValue) * used_virtual_registers[(char) rclass]);
}

static void initializecsedatastructures(void) {
    RegValue *rv;
    char rclass;
    int i;

    nextvaluenumber = 0;

    for (i = 0; i < 428; i++)
        opvalue[i] = NULL;

    for (rclass = 0; rclass < RegClassMax; rclass++) {
        rv = regvalue[(char) rclass];
        for (i = 0; i < used_virtual_registers[(char) rclass]; i++, rv++) {
            rv->number = nextvaluenumber++;
            rv->x4 = 0;
            rv->available = NULL;
        }
    }

    initialize_alias_values();
    stackedvalues = NULL;
    valueceiling = 0x7FFFFFFF;
}

static void labelvalue(AvailableValue *av, PCodeArg *op) {
    ValueLabel *label = oalloc(sizeof(ValueLabel));
    label->op = *op;
    label->next = av->labelled;
    av->labelled = label;
}

static void unlabelvalue(AvailableValue *av, PCodeArg *op) {
    ValueLabel *labelled;
    ValueLabel **ptr;

    ptr = &av->labelled;
    while ((labelled = *ptr)) {
        if (labelled->op.data.reg.reg == op->data.reg.reg)
            *ptr = labelled->next;
        else
            ptr = &labelled->next;
    }
}

static void stackregistervalue(PCodeArg *op, RegValue *value) {
    StackedValue *stacked = oalloc(sizeof(StackedValue));
    stacked->next = stackedvalues;
    stackedvalues = stacked;

    stacked->op = *op;
    stacked->value = *value;
}

static void stackmemoryvalue(Alias *alias) {
    StackedValue *stacked = oalloc(sizeof(StackedValue));
    stacked->next = stackedvalues;
    stackedvalues = stacked;

    stacked->op.kind = PCOp_MEMORY;
    stacked->alias = alias;
    stacked->value.number = alias->valuenumber;
    stacked->valuepcode = alias->valuepcode;
}

static void unstackvalue(StackedValue *stacked) {
    PCodeArg *op = &stacked->op;
    RegValue *value;

    if (stacked->op.kind == PCOp_MEMORY) {
        stacked->alias->valuenumber = stacked->value.number;
        stacked->alias->valuepcode = stacked->valuepcode;
    } else {
        value = &regvalue[op->arg][op->data.reg.reg];
        if (value->available)
            unlabelvalue(value->available, op);
        value->number = stacked->value.number;
        value->x4 = stacked->value.x4;
        value->available = stacked->value.available;
        if (value->available)
            labelvalue(value->available, op);
    }
}

static int samevalue(PCodeArg *op1, PCodeArg *op2) {
    return regvalue[op1->arg][op1->data.reg.reg].number == regvalue[op2->arg][op2->data.reg.reg].number;
}

static int killregister(PCodeArg *op) {
    RegValue *value;

    value = &regvalue[op->arg][op->data.reg.reg];
    if (value->number < valueceiling && nextvaluenumber >= valueceiling)
        stackregistervalue(op, value);

    if (value->available)
        unlabelvalue(value->available, op);
    value->available = NULL;
    value->x4 = 0;
    return value->number = nextvaluenumber++;
}

void killmemory(Alias *alias, PCode *newValue) {
    if (alias->valuenumber < valueceiling && nextvaluenumber >= valueceiling)
        stackmemoryvalue(alias);

    if (newValue) {
        alias->valuenumber = regvalue[newValue->args[0].arg][newValue->args[0].data.reg.reg].number;
        alias->valuepcode = newValue;
    } else {
        alias->valuenumber = nextvaluenumber++;
        alias->valuepcode = NULL;
    }
}

static void killspecificCSEs(short op) {
    AvailableValue *av;
    ValueLabel *labelled;

    for (av = opvalue[op]; av; av = av->next) {
        for (labelled = av->labelled; labelled; labelled = labelled->next)
            killregister(&labelled->op);
    }
}

static void killallCSEs(void) {
    AvailableValue *av;
    ValueLabel *labelled;
    int i;

    for (i = 0; i < 428; i++) {
        for (av = opvalue[i]; av; av = av->next) {
            for (labelled = av->labelled; labelled; labelled = labelled->next)
                killregister(&labelled->op);
        }
    }
}

static void killregisters(PCode *pcode) {
    PCodeArg *op;
    int i;

    for (i = 0, op = pcode->args; i < pcode->argCount; i++, op++) {
        if (op->kind == PCOp_REGISTER && (op->data.reg.effect & EffectWrite))
            killregister(op);
    }
}

static void copyregister(PCodeArg *src, PCodeArg *dest) {
    RegValue *srcvalue;
    RegValue *destvalue;

    srcvalue = &regvalue[src->arg][src->data.reg.reg];
    destvalue = &regvalue[dest->arg][dest->data.reg.reg];

    if (destvalue->number < valueceiling && nextvaluenumber >= valueceiling)
        stackregistervalue(dest, destvalue);

    if (destvalue->available)
        unlabelvalue(destvalue->available, dest);
    destvalue->available = srcvalue->available;
    if (destvalue->available)
        labelvalue(destvalue->available, dest);

    destvalue->number = srcvalue->number;

    if (srcvalue->x4 && srcvalue->number == regvalue[src->arg][srcvalue->x4].number)
        destvalue->x4 = srcvalue->x4;
    else
        destvalue->x4 = src->data.reg.reg;
}

static int matchvalues(AvailableValue *av, PCode *match) {
    PCodeArg *avOp;
    PCodeArg *matchOp;
    int i;

    for (avOp = &av->pcode->args[0], matchOp = &match->args[0], i = 0; i < match->argCount; i++, avOp++, matchOp++) {
        if (i != 0) {
            switch (avOp->kind) {
                case PCOp_REGISTER:
                    if (av->opnumbers[i] != regvalue[matchOp->arg][matchOp->data.reg.reg].number)
                        return 0;
                    break;
                case PCOp_MEMORY:
                    if (matchOp->kind != PCOp_MEMORY)
                        return 0;
                    if (matchOp->data.mem.obj != avOp->data.mem.obj)
                        return 0;
                    if (matchOp->data.mem.offset != avOp->data.mem.offset)
                        return 0;
                    if ((unsigned char) matchOp->arg != (unsigned char) avOp->arg)
                        return 0;
                    break;
                case PCOp_IMMEDIATE:
                    if (matchOp->kind != PCOp_IMMEDIATE)
                        return 0;
                    if (matchOp->data.imm.value != avOp->data.imm.value)
                        return 0;
                    break;
                case PCOp_LABEL:
                    if (matchOp->kind != PCOp_LABEL)
                        return 0;
                    if (matchOp->data.label.label != avOp->data.label.label)
                        return 0;
                    break;
                case PCOp_SYSREG:
                    CError_FATAL(572);
            }
        }
    }

    if ((match->flags & (fIsRead | fPCodeFlag20000)) && match->alias->valuenumber != av->aliasnumber)
        return 0;

    return 1;
}

static void chooselocation(AvailableValue *av, PCodeArg *op) {
    ValueLabel *labelled;
    PCodeArg *baseop;

    baseop = &av->pcode->args[0];
    labelled = av->labelled;
    while (labelled) {
        if (labelled->op.data.reg.reg == baseop->data.reg.reg) {
            *op = labelled->op;
            return;
        }
        labelled = labelled->next;
    }

    *op = av->labelled[0].op;
}

static int findavailablevalue(PCode *pcode, PCodeArg *op) {
    AvailableValue *av;
    PCodeArg tmp1;
    PCodeArg tmp2;

    for (av = opvalue[pcode->op]; av; av = av->next) {
        if (av->labelled && av->pcode->flags == pcode->flags && av->pcode->argCount == pcode->argCount) {
            if (!matchvalues(av, pcode)) {
                if (!(pcode->flags & fCommutative))
                    continue;

                tmp1 = pcode->args[1];
                pcode->args[1] = pcode->args[2];
                pcode->args[2] = tmp1;

                if (!matchvalues(av, pcode)) {
                    tmp2 = pcode->args[1];
                    pcode->args[1] = pcode->args[2];
                    pcode->args[2] = tmp2;
                    continue;
                }
            }
            chooselocation(av, op);
            return 1;
        }
    }

    return 0;
}

static void addavailablevalue(PCode *pcode) {
    AvailableValue *av;
    PCodeArg *op;
    int i;

    av = oalloc(sizeof(AvailableValue) + sizeof(int) * pcode->argCount);
    av->labelled = NULL;
    av->pcode = pcode;
    for (i = 0, op = &pcode->args[0]; i < pcode->argCount; i++, op++) {
        if (op->kind == PCOp_REGISTER)
            av->opnumbers[i] = regvalue[op->arg][op->data.reg.reg].number;
    }

    if (pcode->flags & (fIsRead | fPCodeFlag20000))
        av->aliasnumber = pcode->alias->valuenumber;

    op = &pcode->args[0];
    av->killedregister = killregister(op);
    labelvalue(av, op);
    regvalue[op->arg][op->data.reg.reg].available = av;
    av->next = opvalue[pcode->op];
    opvalue[pcode->op] = av;
}

static int isCSEop(PCode *pcode) {
    PCodeArg *baseOp;
    PCodeArg *op;
    int i;

    baseOp = &pcode->args[0];

    switch (pcode->op) {
        case PC_CMPI:
        case PC_CMP:
        case PC_CMPLI:
        case PC_CMPL:
        case PC_FCMPU:
        case PC_FCMPO:
            if (!moreaggressiveoptimization)
                return 0;
            break;
        case PC_LI:
        case PC_LIS:
            if (!moreaggressiveoptimization)
                return 0;
            if (pcode->args[0].data.reg.reg < first_fe_temporary_register[RegClass_GPR] || pcode->args[0].data.reg.reg > last_temporary_register[RegClass_GPR])
                return 0;
            break;
    }

    if (PCODE_FLAG_SET_F(pcode) & (fIsVolatile | fSideEffects | fOverflow | fSetsCarry | fRecordBit))
        return 0;

    for (i = 0, op = &pcode->args[0]; i < pcode->argCount; i++, op++) {
        if (op != baseOp &&
            op->kind == baseOp->kind &&
            op->arg == baseOp->arg &&
            op->data.reg.reg == baseOp->data.reg.reg)
            return 0;
    }

    return 1;
}

static int isCSEload(PCode *pcode) {
    PCodeArg *op;
    int i;
    int count;

    count = 0;
    for (i = 0, op = &pcode->args[0]; i < pcode->argCount; i++, op++) {
        if (op->kind == PCOp_REGISTER && (op->data.reg.effect & EffectWrite))
            count++;
    }

    return count == 1;
}

static void registercopy(PCode *pcode) {
    PCodeArg *op1;
    PCodeArg *op2;

    op1 = &pcode->args[0];
    op2 = &pcode->args[1];
    if (samevalue(op2, op1))
        deletepcode(pcode);
    else
        copyregister(op2, op1);
}

static PCode *recentlystored(Alias *alias, PCodeArg *op) {
    PCode *pc;
    if ((pc = alias->valuepcode) && alias->valuenumber == regvalue[pc->args[0].arg][pc->args[0].data.reg.reg].number) {
        *op = pc->args[0];
        return pc;
    } else {
        return NULL;
    }
}

static void simpleload(PCode *pcode) {
    PCodeArg *origOp;
    PCodeArg op;
    PCode *rs;

    origOp = &pcode->args[0];
    if ((pcode->flags & fIsVolatile) || !isCSEload(pcode)) {
        killregisters(pcode);
        return;
    }

    if (findavailablevalue(pcode, &op)) {
        if (!samevalue(origOp, &op)) {
            insertpcodebefore(pcode, makecopyinstruction(&op, origOp));
            copyregister(&op, origOp);
        }
        deletepcode(pcode);
        removedcommonsubexpressions = 1;
    } else if ((rs = recentlystored(pcode->alias, &op)) && can_reuse_stored_value(rs, pcode)) {
        if (!samevalue(origOp, &op)) {
            insertpcodebefore(pcode, makecopyinstruction(&op, origOp));
            copyregister(&op, origOp);
        }
        deletepcode(pcode);
        removedcommonsubexpressions = 1;
    } else {
        addavailablevalue(pcode);
    }
}

static void simplestore(PCode *pcode) {
    update_alias_value(pcode->alias, pcode);
    killregisters(pcode);
}

static void pointerload(PCode *pcode) {
    PCodeArg *op;
    PCodeArg buf;

    op = &pcode->args[0];

    if ((pcode->flags & fIsVolatile) || !isCSEload(pcode)) {
        killregisters(pcode);
        return;
    }

    if (findavailablevalue(pcode, &buf)) {
        if (!samevalue(op, &buf)) {
            insertpcodebefore(pcode, makecopyinstruction(&buf, op));
            copyregister(&buf, op);
        }
        deletepcode(pcode);
        removedcommonsubexpressions = 1;
    } else {
        addavailablevalue(pcode);
    }
}

static void pointerstore(PCode *pcode) {
    update_alias_value(pcode->alias, NULL);
    killregisters(pcode);
}

static void arithmeticop(PCode *pcode) {
    PCodeArg *op;
    PCodeArg buf;

    op = &pcode->args[0];

    if (findavailablevalue(pcode, &buf)) {
        if (!samevalue(op, &buf)) {
            insertpcodebefore(pcode, makecopyinstruction(&buf, op));
            copyregister(&buf, op);
        }
        deletepcode(pcode);
        removedcommonsubexpressions = 1;
    } else {
        addavailablevalue(pcode);
    }
}

static void functioncall(PCode *pcode) {
    killregisters(pcode);
    if (coloring) {
        update_all_alias_values();
        killallCSEs();
    } else {
        update_alias_value(pcode->alias, NULL);
    }
}

static void operatefrommemory(PCode *pcode) {
    CError_FATAL(980);
}

static void operatetomemory(PCode *pcode) {
    CError_FATAL(1011);
}

static void propagatecopiesto(PCode *pcode) {
    PCodeArg *op;
    int i;

    for (i = 0, op = &pcode->args[0]; i < pcode->argCount; i++, op++) {
        if (
            op->kind == PCOp_REGISTER &&
            (op->data.reg.effect & (EffectRead | EffectWrite | Effect8)) == EffectRead &&
            op->data.reg.reg >= n_real_registers[op->arg] &&
            regvalue[op->arg][op->data.reg.reg].x4 &&
            regvalue[op->arg][op->data.reg.reg].x4 >= n_real_registers[op->arg] &&
            regvalue[op->arg][op->data.reg.reg].number == regvalue[op->arg][regvalue[op->arg][op->data.reg.reg].x4].number
            ) {
            op->data.reg.reg = regvalue[op->arg][op->data.reg.reg].x4;
        }
    }
}

static void removecsesfrombasicblock(PCodeBlock *block) {
    PCode *pcode;
    PCode *next;

    for (pcode = block->firstPCode; pcode; pcode = next) {
        next = pcode->nextPCode;
        propagatecopiesto(pcode);
        if (pcode->flags & fIsMove) {
            registercopy(pcode);
        } else if ((pcode->flags & fIsCall) && (pcode->flags & (fLink | fSideEffects))) {
            functioncall(pcode);
        } else if (pcode->flags & fIsRead) {
            if (pcode->flags & fIsPtrOp)
                pointerload(pcode);
            else
                simpleload(pcode);
        } else if (pcode->flags & fIsWrite) {
            if (pcode->flags & fIsPtrOp)
                pointerstore(pcode);
            else
                simplestore(pcode);
        } else if (pcode->flags & fPCodeFlag20000) {
            operatefrommemory(pcode);
        } else if (pcode->flags & fPCodeFlag40000) {
            operatetomemory(pcode);
        } else if ((pcode->flags & fIsCSE) && isCSEop(pcode)) {
            arithmeticop(pcode);
        } else {
            killregisters(pcode);
        }
    }

    block->flags |= fVisited;
}

static void getvaluestate(State *state) {
    state->stackedvalues = stackedvalues;
    state->valueceiling = valueceiling;
}

static void setvaluestate(State *state) {
    stackedvalues = state->stackedvalues;
    valueceiling = state->valueceiling;
}

static void forkvaluestate(int number) {
    stackedvalues = NULL;
    valueceiling = number;
}

static void regressvaluestate(void) {
    AvailableValue *av;
    AvailableValue **ptr;
    int i;
    StackedValue *stacked;

    for (i = 0; i < 428; i++) {
        ptr = &opvalue[i];
        while ((av = *ptr)) {
            if (av->killedregister >= valueceiling)
                *ptr = av->next;
            else
                ptr = &av->next;
        }
    }

    for (stacked = stackedvalues; stacked; stacked = stacked->next)
        unstackvalue(stacked);
}

static void removecsesfromextendedbasicblock(PCodeBlock *block) {
    PCLink *succ;
    int counter;
    State state;

    removecsesfrombasicblock(block);
    while (block->successors &&
        !block->successors->nextLink &&
        block->successors->block->predecessors &&
        !block->successors->block->predecessors->nextLink) {
        block = block->successors->block;
        removecsesfrombasicblock(block);
    }

    counter = 0;
    for (succ = block->successors; succ; succ = succ->nextLink) {
        if (!(succ->block->flags & fVisited) && succ->block->predecessors && !succ->block->predecessors->nextLink)
            counter++;
    }

    if (counter) {
        getvaluestate(&state);
        forkvaluestate(nextvaluenumber);
        for (succ = block->successors; succ; succ = succ->nextLink) {
            if (!(succ->block->flags & fVisited) && succ->block->predecessors && !succ->block->predecessors->nextLink) {
                removecsesfromextendedbasicblock(succ->block);
                regressvaluestate();
            }
        }
        setvaluestate(&state);
    }
}

void removecommonsubexpressions(Object *proc, int flag) {
    PCodeBlock *block;

    moreaggressiveoptimization = flag;
    removedcommonsubexpressions = 0;
    gather_alias_info();
    allocatecsedatastructures();

    for (block = pcbasicblocks; block; block = block->nextBlock)
        block->flags &= ~fVisited;

    for (block = pcbasicblocks; block; block = block->nextBlock) {
        if (!(block->flags & fVisited)) {
            initializecsedatastructures();
            removecsesfromextendedbasicblock(block);
        }
    }

    freeoheap();
}