MWCC/compiler_and_linker/unsorted/CodeMotion.c

#include "compiler/CodeMotion.h"
#include "compiler/Alias.h"
#include "compiler/BitVectors.h"
#include "compiler/LoopDetection.h"
#include "compiler/LoopOptimization.h"
#include "compiler/CompilerTools.h"
#include "compiler/PCode.h"
#include "compiler/UseDefChains.h"
#include "compiler/RegisterInfo.h"

int movedloopinvariantcode;
int unswitchedinvariantcode;

static int isloopinvariant(PCode *pcode, Loop *loop, UInt32 *vec, int flag1, int flag2) {
    PCodeArg *op;
    RegUseOrDef *list;
    int i;

    if (pcode->flags & (fPCodeFlag2 | fPCodeFlag4 | fPCodeFlag20000 | fPCodeFlag40000)) {
        if (pcode->alias) {
            if (pcode->alias->type == AliasType2 || (pcode->flags & (fIsVolatile | fSideEffects)))
                return 0;

            if (pcode->flags & fPCodeFlag2) {
                for (list = findobjectusedef(pcode->alias->object)->defs; list; list = list->next) {
                    if (
                        may_alias(pcode, Defs[list->id].pcode) &&
                        bitvectorgetbit(list->id, vec) &&
                        bitvectorgetbit(Defs[list->id].pcode->block->blockIndex, loop->memberblocks)
                        )
                        return 0;
                }
            }

            if (pcode->flags & fPCodeFlag4) {
                for (list = findobjectusedef(pcode->alias->object)->uses; list; list = list->next) {
                    if (
                        may_alias(pcode, Uses[list->id].pcode) &&
                        bitvectorgetbit(Uses[list->id].pcode->block->blockIndex, loop->memberblocks)
                        )
                        return 0;
                }
            }
        } else {
            return 0;
        }
    }

    if ((pcode->flags & fPCodeFlag4) && !bitvectorgetbit(pcode->block->blockIndex, loop->vec2C))
        return 0;

    op = pcode->args;
    i = pcode->argCount;
    while (i--) {
        switch (op->kind) {
            case PCOp_MEMORY:
                if ((pcode->flags & fPCodeFlag2) && ((pcode->flags == 0) & 0x40)) {
                    for (list = findobjectusedef(op->data.mem.obj)->defs; list; list = list->next) {
                        if (
                            may_alias(pcode, Defs[list->id].pcode) &&
                            bitvectorgetbit(list->id, vec) &&
                            bitvectorgetbit(Defs[list->id].pcode->block->blockIndex, loop->memberblocks)
                            )
                            return 0;
                    }
                }
                if (pcode->flags & fPCodeFlag4) {
                    for (list = findobjectusedef(op->data.mem.obj)->uses; list; list = list->next) {
                        if (
                            may_alias(pcode, Uses[list->id].pcode) &&
                            bitvectorgetbit(Uses[list->id].pcode->block->blockIndex, loop->memberblocks)
                            )
                            return 0;
                    }
                }
                break;
            case PCOp_REGISTER:
                if (op->data.reg.effect & (EffectRead | EffectWrite)) {
                    if (op->kind == PCOp_REGISTER && op->arg == RegClass_GPR) {
                        if (op->data.reg.reg == _FP_)
                            break;
                        if (op->data.reg.reg == _CALLER_SP_)
                            break;
                        if (op->data.reg.reg == 2)
                            break;
                    }
                    if (op->data.reg.reg < n_real_registers[op->arg]) {
                        if (op->arg == RegClass_CRFIELD) {
                            if (!flag2 || (op->data.reg.effect & EffectRead))
                                return 0;
                        } else if (op->arg == RegClass_SPR) {
                            if (!flag1)
                                return 0;
                        } else {
                            return 0;
                        }
                    } else if (op->data.reg.effect & EffectRead) {
                        if (flag1 && op->kind == PCOp_REGISTER && op->arg == RegClass_SPR)
                            break;
                        if (op->kind == PCOp_REGISTER && op->arg == RegClass_GPR) {
                            if (op->data.reg.reg == _FP_)
                                break;
                            if (op->data.reg.reg == _CALLER_SP_)
                                break;
                            if (op->data.reg.reg == 2)
                                break;
                        }

                        for (list = reg_Defs[op->arg][op->data.reg.reg]; list; list = list->next) {
                            if (
                                bitvectorgetbit(list->id, vec) &&
                                bitvectorgetbit(Defs[list->id].pcode->block->blockIndex, loop->memberblocks)
                                )
                                return 0;
                        }
                    }
                }
                break;
        }
        op++;
    }

    return 1;
}

static int isuniquedefinition(PCode *pcode, Loop *loop) {
    RegUseOrDef *list;
    int defID;
    UseOrDef *def;

    defID = pcode->defID;
    def = &Defs[defID];
    if (defID >= number_of_Defs)
        return 0;
    if (def->pcode != pcode)
        return 0;
    if ((defID + 1) < number_of_Defs && def[1].pcode == pcode)
        return 0;

    if (def->v.kind == PCOp_REGISTER) {
        for (list = reg_Defs[def->v.arg][def->v.u.reg]; list; list = list->next) {
            if (
                bitvectorgetbit(Defs[list->id].pcode->block->blockIndex, loop->memberblocks) &&
                list->id != defID
                )
                return 0;
        }
    } else if (def->v.kind == PCOp_MEMORY) {
        for (list = findobjectusedef(def->v.u.object)->defs; list; list = list->next) {
            if (
                may_alias(pcode, Defs[list->id].pcode) &&
                bitvectorgetbit(Defs[list->id].pcode->block->blockIndex, loop->memberblocks) &&
                list->id != defID
                )
                return 0;
        }
    } else {
        CError_FATAL(292);
    }

    return 1;
}

static int uniquelyreachesuse(int defID, int useID) {
    UseOrDef *def;
    UseOrDef *use;
    RegUseOrDef *list;
    PCode *pcode;

    def = &Defs[defID];
    use = &Uses[useID];
    if (def->v.kind == PCOp_REGISTER) {
        for (list = reg_Defs[def->v.arg][def->v.u.reg]; list; list = list->next) {
            if (
                list->id != defID &&
                bitvectorgetbit(list->id, usedefinfo[use->pcode->block->blockIndex].defvec8)
                )
                break;
        }
    } else if (def->v.kind == PCOp_MEMORY) {
        for (list = findobjectusedef(def->v.u.object)->defs; list; list = list->next) {
            if (
                may_alias(def->pcode, Defs[list->id].pcode) &&
                list->id != defID &&
                bitvectorgetbit(list->id, usedefinfo[use->pcode->block->blockIndex].defvec8)
                )
                break;
        }
    }

    if (!list)
        return 1;

    if (def->pcode->block == use->pcode->block) {
        for (pcode = use->pcode->prevPCode; pcode; pcode = pcode->prevPCode) {
            if (pcode == def->pcode)
                return 1;
        }
    }

    return 0;
}

static int uniquelyreachesalluses(int defID, Loop *loop) {
    UseOrDef *def;
    RegUseOrDef *list;

    def = &Defs[defID];

    if (def->v.kind == PCOp_REGISTER) {
        for (list = reg_Uses[def->v.arg][def->v.u.reg]; list; list = list->next) {
            if (
                bitvectorgetbit(list->id, usedefinfo[loop->preheader->blockIndex].usevec1C) ||
                (bitvectorgetbit(Uses[list->id].pcode->block->blockIndex, loop->memberblocks) && !uniquelyreachesuse(defID, list->id))
                )
                return 0;
        }
    } else if (def->v.kind == PCOp_MEMORY) {
        for (list = findobjectusedef(def->v.u.object)->uses; list; list = list->next) {
            if (may_alias(def->pcode, Uses[list->id].pcode)) {
                if (
                    bitvectorgetbit(list->id, usedefinfo[loop->preheader->blockIndex].usevec1C) ||
                    (bitvectorgetbit(Uses[list->id].pcode->block->blockIndex, loop->memberblocks) && !uniquelyreachesuse(defID, list->id))
                    )
                    return 0;
            }
        }
    } else {
        CError_FATAL(382);
    }

    return 1;
}

static int isliveonexit(TinyValue *v, Loop *loop) {
    RegUseOrDef *list;
    UInt32 *vec;

    vec = usedefinfo[loop->preheader->blockIndex].usevec1C;

    if (v->kind == PCOp_REGISTER) {
        for (list = reg_Uses[v->arg][v->u.reg]; list; list = list->next) {
            if (
                bitvectorgetbit(list->id, vec) &&
                !bitvectorgetbit(Uses[list->id].pcode->block->blockIndex, loop->memberblocks)
                )
                return 1;
        }
    } else if (v->kind == PCOp_MEMORY) {
        for (list = findobjectusedef(v->u.object)->uses; list; list = list->next) {
            if (
                bitvectorgetbit(list->id, vec) &&
                !bitvectorgetbit(Uses[list->id].pcode->block->blockIndex, loop->memberblocks)
                )
                return 1;
        }
    }

    return 0;
}

static int dominatesallexits(PCode *pcode, Loop *loop) {
    return bitvectorgetbit(pcode->block->blockIndex, loop->vec28) != 0;
}

static int maymove(PCode *pcode, Loop *loop) {
    short reg;

    if (!isuniquedefinition(pcode, loop))
        return 0;
    if (!uniquelyreachesalluses(pcode->defID, loop))
        return 0;
    if (!dominatesallexits(pcode, loop) && isliveonexit(&Defs[pcode->defID].v, loop))
        return 0;

    if (loop->bodySize > 25) {
        switch (pcode->op) {
            case PC_LI:
                if (
                    pcode->nextPCode &&
                    pcode->nextPCode->op == PC_LVX &&
                    (pcode->nextPCode->flags & fIsConst)
                    ) {
                    reg = pcode->args[0].data.reg.reg;
                    if (pcode->nextPCode->args[1].data.reg.reg == reg ||
                         pcode->nextPCode->args[2].data.reg.reg == reg)
                        return 1;
                }
            case PC_VSPLTISB:
            case PC_VSPLTISH:
            case PC_VSPLTISW:
                return 0;
            default:
                if (!bitvectorgetbit(pcode->block->blockIndex, loop->vec2C))
                    return 0;
        }
    }

    return 1;
}

static void moveinvariantcomputation(PCode *pcode, Loop *loop) {
    ObjectUseDef *oud;
    BlockList *blocklist;
    RegUseOrDef *list;
    UseOrDef *def;
    int defID;

    defID = pcode->defID;
    def = &Defs[defID];
    deletepcode(pcode);
    insertpcodebefore(loop->preheader->lastPCode, pcode);
    loop->bodySize--;
    movedloopinvariantcode = 1;

    if (def->v.kind == PCOp_REGISTER) {
        for (blocklist = loop->blocks; blocklist; blocklist = blocklist->next) {
            for (list = reg_Defs[def->v.arg][def->v.u.reg]; list; list = list->next)
                bitvectorclearbit(list->id, usedefinfo[blocklist->block->blockIndex].defvec8);
            bitvectorsetbit(defID, usedefinfo[blocklist->block->blockIndex].defvec8);
        }
    } else if (def->v.kind == PCOp_MEMORY) {
        oud = findobjectusedef(def->v.u.object);
        for (blocklist = loop->blocks; blocklist; blocklist = blocklist->next) {
            for (list = oud->defs; list; list = list->next) {
                if (uniquely_aliases(pcode, Defs[list->id].pcode))
                    bitvectorclearbit(list->id, usedefinfo[blocklist->block->blockIndex].defvec8);
            }
            bitvectorsetbit(defID, usedefinfo[blocklist->block->blockIndex].defvec8);
        }
    } else {
        CError_FATAL(545);
    }
}

static int srawi_addze_maymove(PCode *pcode, Loop *loop) {
    RegUseOrDef *list;
    UseOrDef *def;
    int defID;
    int nextDefID;

    defID = pcode->defID;
    nextDefID = pcode->nextPCode->defID;

    def = &Defs[defID];
    if (defID >= number_of_Defs)
        return 0;
    if (def->pcode != pcode)
        return 0;
    if ((defID + 1) < number_of_Defs && def[1].pcode == pcode)
        return 0;

    if (def->v.kind == PCOp_REGISTER && def->v.arg == RegClass_GPR) {
        for (list = reg_Defs[RegClass_GPR][def->v.u.reg]; list; list = list->next) {
            if (
                bitvectorgetbit(Defs[list->id].pcode->block->blockIndex, loop->memberblocks) &&
                list->id != defID &&
                list->id != nextDefID
                )
                return 0;
        }
    } else {
        CError_FATAL(582);
    }

    if (!uniquelyreachesalluses(pcode->defID, loop))
        return 0;
    if (!dominatesallexits(pcode, loop) && isliveonexit(&Defs[pcode->defID].v, loop))
        return 0;
    if (!dominatesallexits(pcode->nextPCode, loop) && isliveonexit(&Defs[pcode->nextPCode->defID].v, loop))
        return 0;

    return 1;
}

static int srawi_addze_isloopinvariant(PCode *pcode, Loop *loop, UInt32 *vec) {
    static PCode *oldNextInstr;
    PCode *nextInstr;

    nextInstr = pcode->nextPCode;
    if (
        pcode->op == PC_ADDZE &&
        oldNextInstr == pcode
        ) {
        oldNextInstr = NULL;
        return 1;
    } else if (
        pcode->op == PC_SRAWI &&
        nextInstr &&
        nextInstr->op == PC_ADDZE &&
        pcode->args[0].data.reg.reg == nextInstr->args[0].data.reg.reg &&
        nextInstr->args[0].data.reg.reg == nextInstr->args[1].data.reg.reg &&
        !(pcode->flags & (fPCodeFlag8 | fPCodeFlag20 | fIsVolatile | fSideEffects)) &&
        !(nextInstr->flags & (fPCodeFlag8 | fPCodeFlag20 | fIsVolatile | fSideEffects)) &&
        isloopinvariant(pcode, loop, vec, 1, 0) &&
        srawi_addze_maymove(pcode, loop)
        ) {
        oldNextInstr = nextInstr;
        return 1;
    } else {
        oldNextInstr = NULL;
        return 0;
    }
}

static void removeblockfromloop(Loop *loop, PCodeBlock *block) {
    BlockList *list;
    BlockList **ptr;

    bitvectorclearbit(block->blockIndex, loop->memberblocks);
    bitvectorclearbit(block->blockIndex, loop->vec24);
    bitvectorclearbit(block->blockIndex, loop->vec28);
    bitvectorclearbit(block->blockIndex, loop->vec2C);
    loop->bodySize -= block->pcodeCount;

    ptr = &loop->blocks;
    while ((list = *ptr)) {
        if (list->block == block)
            *ptr = list->next;
        else
            ptr = &list->next;
    }
}

static void changesuccessor(PCodeBlock *block, PCodeBlock *from, PCodeBlock *to) {
    PCLink **ptr;
    PCLink *link;

    for (link = block->successors; link; link = link->nextLink) {
        if (link->block == from)
            link->block = to;
    }

    ptr = &from->predecessors;
    while ((link = *ptr)) {
        if (link->block == block) {
            *ptr = link->nextLink;
            link->nextLink = to->predecessors;
            to->predecessors = link;
        } else {
            ptr = &link->nextLink;
        }
    }
}

static void movesuccessor(PCodeBlock *to, PCodeBlock *from, PCodeBlock *block) {
    PCLink **ptr;
    PCLink *link;

    for (link = block->predecessors; link; link = link->nextLink) {
        if (link->block == from)
            link->block = to;
    }

    ptr = &from->successors;
    while ((link = *ptr)) {
        if (link->block == block) {
            *ptr = link->nextLink;
            link->nextLink = to->successors;
            to->successors = link;
        } else {
            ptr = &link->nextLink;
        }
    }
}

static void movecmptopreheader(Loop *loop, PCodeBlock *block, PCode *pc1, PCode *pc2, PCodeArg *op) {
    PCodeBlock *preheader;
    PCode *pc3;

    preheader = loop->preheader;
    if (PCODE_FLAG_SET_F(pc1) & fPCodeFlag20000000) {
        moveinvariantcomputation(pc1, loop);
    } else {
        deletepcode(pc1);
        insertpcodebefore(loop->preheader->lastPCode, pc1);
        loop->bodySize--;
        movedloopinvariantcode = 1;
    }
    loop->preheader = NULL;

    insertpreheaderblock(loop);

    pc3 = preheader->lastPCode;
    CError_ASSERT(775, pc3->op == PC_B);
    deletepcode(pc3);
    deletepcode(pc2);
    appendpcode(preheader, pc2);
    movesuccessor(preheader, block, op->data.label.label->block);
}

static PCodeBlock *appendheadercopy(Loop *loop, PCodeBlock *block1, PCodeBlock *block2, PCodeBlock *block3) {
    PCodeBlock *newblock1;
    PCodeBlock *newblock2;
    PCLink *link;
    PCode *scan;

    newblock1 = lalloc(sizeof(PCodeBlock));
    newblock2 = lalloc(sizeof(PCodeBlock));

    newblock1->labels = NULL;
    newblock1->predecessors = newblock1->successors = NULL;
    newblock1->firstPCode = newblock1->lastPCode = NULL;
    newblock1->pcodeCount = 0;
    newblock1->loopWeight = loop->body->loopWeight;
    newblock1->flags = 0;
    newblock1->blockIndex = pcblockcount++;

    newblock2->labels = NULL;
    newblock2->predecessors = newblock2->successors = NULL;
    newblock2->firstPCode = newblock2->lastPCode = NULL;
    newblock2->pcodeCount = 0;
    newblock2->loopWeight = loop->body->loopWeight;
    newblock2->flags = 0;
    newblock2->blockIndex = pcblockcount++;

    newblock1->nextBlock = newblock2;
    newblock2->prevBlock = newblock1;
    newblock1->prevBlock = block1;
    newblock2->nextBlock = block1->nextBlock;
    block1->nextBlock = newblock1;
    newblock2->nextBlock->prevBlock = newblock2;

    pclabel(newblock1, makepclabel());
    pclabel(newblock2, makepclabel());

    changesuccessor(block1, block1->successors->block, newblock1);

    link = lalloc(sizeof(PCLink));
    link->block = newblock2;
    link->nextLink = newblock1->successors;
    newblock1->successors = link;

    link = lalloc(sizeof(PCLink));
    link->block = newblock1;
    link->nextLink = newblock2->predecessors;
    newblock2->predecessors = link;

    appendpcode(newblock2, makepcode(PC_B, block2->nextBlock->labels));
    pcbranch(newblock2, block2->nextBlock->labels);
    pccomputepredecessors1(newblock2);

    for (scan = block2->firstPCode; scan; scan = scan->nextPCode)
        appendpcode(newblock1, copypcode(scan));

    pcbranch(newblock1, block3->labels);

    link = lalloc(sizeof(PCLink));
    link->block = newblock1;
    link->nextLink = block3->predecessors;
    block3->predecessors = link;

    addblocktoloop(loop, newblock1);
    if (bitvectorgetbit(block2->blockIndex, loop->vec28))
        bitvectorsetbit(newblock1->blockIndex, loop->vec28);
    if (bitvectorgetbit(block2->blockIndex, loop->vec2C))
        bitvectorsetbit(newblock1->blockIndex, loop->vec2C);

    for (loop = loop->parent; loop; loop = loop->parent) {
        addblocktoloop(loop, newblock1);
        if (bitvectorgetbit(block2->blockIndex, loop->vec28))
            bitvectorsetbit(newblock1->blockIndex, loop->vec28);
        if (bitvectorgetbit(block2->blockIndex, loop->vec2C))
            bitvectorsetbit(newblock1->blockIndex, loop->vec2C);

        addblocktoloop(loop, newblock2);
        if (bitvectorgetbit(block2->blockIndex, loop->vec28))
            bitvectorsetbit(newblock2->blockIndex, loop->vec28);
        if (bitvectorgetbit(block2->blockIndex, loop->vec2C))
            bitvectorsetbit(newblock2->blockIndex, loop->vec2C);
    }

    return newblock1;
}

static BlockList *findswitchpath(Loop *loop, PCodeBlock *block) {
    BlockList *head;
    BlockList *tail;
    BlockList *node;
    PCodeBlock *scan;

    head = NULL;
    tail = NULL;

    for (scan = block; scan && scan != loop->body; scan = scan->successors->block) {
        if (!bitvectorgetbit(scan->blockIndex, loop->memberblocks))
            return NULL;
        if (scan->successors && scan->successors->nextLink)
            return NULL;

        node = oalloc(sizeof(BlockList));
        node->block = scan;
        node->next = NULL;
        if (head) {
            tail->next = node;
            tail = node;
        } else {
            head = node;
            tail = node;
        }
    }

    return head;
}

static void simpleunswitchloop(Loop *loop) {
    PCode *pc29;
    PCodeArg *op27;
    UInt32 *myvec;
    PCodeBlock *block26;
    PCode *pc25; // r25
    BlockList *path2_24;
    PCodeArg *op23;
    PCode *pc23; // r23
    BlockList *scanlist; // r23
    BlockList *bestpath1; // r23
    BlockList *bestpath2; // r22
    PCodeBlock *headercopy; // r22
    Loop *newloop; // r21
    PCodeBlock *preheader21;
    BlockList *path20;
    PCode *scan20;
    PCode *lastpcode;
    int i;
    BlockList *pathiter1;
    BlockList *pathiter2;

    if (!(lastpcode = loop->body->lastPCode))
        return;
    if (lastpcode->op != PC_BT && lastpcode->op != PC_BF)
        return;
    if (lastpcode->args[2].kind != PCOp_LABEL)
        return;
    if (!bitvectorgetbit(lastpcode->args[2].data.label.label->block->blockIndex, loop->memberblocks))
        return;
    if (loop->x57)
        return;
    if (loop->x4D)
        return;
    if (bitvectorgetbit(loop->body->nextBlock->blockIndex, loop->memberblocks))
        return;

    for (block26 = pcbasicblocks; block26; block26 = block26->nextBlock) {
        if (bitvectorgetbit(block26->blockIndex, loop->memberblocks))
            break;
    }

    if (!block26)
        return;

    myvec = oalloc(4 * ((number_of_Defs + 31) >> 5));
    bitvectorcopy(myvec, usedefinfo[block26->blockIndex].defvec8, number_of_Defs);
    for (pc25 = loop->preheader->nextBlock->firstPCode; pc25; pc25 = pc25->nextPCode) {
        if (!(PCODE_FLAG_SET_F(pc25) & (fPCodeFlag8 | fPCodeFlag20 | fIsVolatile | fSideEffects | fPCodeFlag20000000))) {
            if (isloopinvariant(pc25, loop, myvec, 0, 1))
                break;
        }
    }

    if (!pc25 || pc25->argCount < 1)
        return;

    if (
        pc25->argCount < 1 ||
        pc25->args[0].kind != PCOp_REGISTER ||
        pc25->args[0].arg != RegClass_CRFIELD
        )
        return;

    pc29 = pc25->block->lastPCode;
    if (
        !pc29 ||
        !(pc29->flags & fPCodeFlag1) ||
        pc29->args[0].kind != PCOp_REGISTER ||
        pc29->args[0].arg != RegClass_CRFIELD
        )
        return;

    if (pc29->args[0].data.reg.reg != pc25->args[0].data.reg.reg)
        return;

    op27 = NULL;
    for (i = 0; i < pc29->argCount; i++) {
        if (pc29->args[i].kind == PCOp_LABEL)
            op27 = &pc29->args[i];
    }

    if (op27) {
        preheader21 = loop->preheader;

        path20 = findswitchpath(loop, block26->nextBlock);
        if (!path20)
            return;

        path2_24 = findswitchpath(loop, op27->data.label.label->block);
        if (!path2_24)
            return;

        bestpath1 = NULL;
        bestpath2 = NULL;
        for (pathiter1 = path20; pathiter1; pathiter1 = pathiter1->next) {
            for (pathiter2 = path2_24; pathiter2; pathiter2 = pathiter2->next) {
                if (pathiter1->block == pathiter2->block) {
                    bestpath1 = pathiter1;
                    break;
                }
            }
            if (bestpath1)
                break;
            bestpath2 = pathiter1;
        }

        CError_ASSERT(1192, bestpath2->block);

        if (bestpath2->block->lastPCode && bestpath2->block->lastPCode->op == PC_B)
            deletepcode(bestpath2->block->lastPCode);

        while (bestpath1) {
            for (scan20 = bestpath1->block->firstPCode; scan20; scan20 = scan20->nextPCode) {
                if (scan20->op != PC_B)
                    appendpcode(bestpath2->block, copypcode(scan20));
            }
            bestpath1 = bestpath1->next;
        }

        headercopy = appendheadercopy(loop, bestpath2->block, loop->body, block26);
        movecmptopreheader(loop, block26, pc25, pc29, op27);

        if (block26->pcodeCount) {
            if (path2_24->block->firstPCode) {
                pc23 = path2_24->block->firstPCode;
                for (scan20 = block26->firstPCode; scan20; scan20 = scan20->nextPCode) {
                    if (scan20->op != PC_B)
                        insertpcodebefore(pc23, copypcode(scan20));
                }
            } else {
                for (scan20 = block26->firstPCode; scan20; scan20 = scan20->nextPCode) {
                    if (scan20->op != PC_B)
                        appendpcode(path2_24->block, copypcode(scan20));
                }
            }
        }

        op23 = NULL;
        for (i = 0; i < loop->body->lastPCode->argCount; i++) {
            if (loop->body->lastPCode->args[i].kind == PCOp_LABEL)
                op23 = &loop->body->lastPCode->args[i];
        }

        CError_ASSERT(1250, op23 != NULL);

        changesuccessor(loop->body, op23->data.label.label->block, path2_24->block);
        op23->data.label.label = path2_24->block->labels;

        op23 = NULL;
        for (i = 0; i < preheader21->lastPCode->argCount; i++) {
            if (preheader21->lastPCode->args[i].kind == PCOp_LABEL)
                op23 = &preheader21->lastPCode->args[i];
        }

        CError_ASSERT(1267, op23 != NULL);

        changesuccessor(preheader21, op23->data.label.label->block, loop->body);
        op23->data.label.label = loop->body->labels;

        op23 = NULL;
        for (i = 0; i < loop->preheader->lastPCode->argCount; i++) {
            if (loop->preheader->lastPCode->args[i].kind == PCOp_LABEL)
                op23 = &loop->preheader->lastPCode->args[i];
        }

        CError_ASSERT(1284, op23 != NULL);

        changesuccessor(loop->preheader, op23->data.label.label->block, headercopy);
        op23->data.label.label = headercopy->labels;

        newloop = lalloc(sizeof(Loop));
        newloop->parent = loop->parent;
        newloop->children = NULL;
        newloop->nextSibling = loop->nextSibling;
        loop->nextSibling = newloop;
        newloop->body = loop->body;
        newloop->preheader = NULL;
        newloop->blocks = NULL;
        newloop->basicInductionVars = NULL;
        newloop->footer = NULL;
        newloop->pc18 = NULL;
        newloop->loopWeight = loop->loopWeight;

        bitvectorinitialize(newloop->memberblocks = lalloc(4 * ((loopdetection_nblocks + 31) >> 5)), loopdetection_nblocks, 0);
        bitvectorinitialize(newloop->vec24 = lalloc(4 * ((loopdetection_nblocks + 31) >> 5)), loopdetection_nblocks, 0);
        bitvectorinitialize(newloop->vec28 = lalloc(4 * ((loopdetection_nblocks + 31) >> 5)), loopdetection_nblocks, 0);
        bitvectorinitialize(newloop->vec2C = lalloc(4 * ((loopdetection_nblocks + 31) >> 5)), loopdetection_nblocks, 0);

        removeblockfromloop(loop, newloop->body);
        addblocktoloop(newloop, newloop->body);

        bitvectorsetbit(newloop->body->blockIndex, newloop->vec24);
        bitvectorsetbit(newloop->body->blockIndex, newloop->vec2C);
        bitvectorsetbit(newloop->body->blockIndex, newloop->vec28);

        for (scanlist = path2_24; scanlist; scanlist = scanlist->next) {
            removeblockfromloop(loop, scanlist->block);
            addblocktoloop(newloop, scanlist->block);
            bitvectorsetbit(scanlist->block->blockIndex, newloop->vec2C);
        }

        newloop->preheader = NULL;
        insertpreheaderblock(newloop);
        analyzeloop(newloop);

        loop->body = headercopy;

        for (scanlist = loop->blocks; scanlist; scanlist = scanlist->next)
            bitvectorsetbit(scanlist->block->blockIndex, loop->vec2C);

        bitvectorsetbit(headercopy->blockIndex, loop->vec24);
        analyzeloop(loop);

        unswitchedinvariantcode = 1;
    }
}

static void simpleunswitchloops(Loop *loop) {
    while (loop) {
        if (loop->children)
            simpleunswitchloops(loop->children);
        else if (!loop->x4F)
            simpleunswitchloop(loop);
        loop = loop->nextSibling;
    }
}

static void moveinvariantsfromloop(Loop *loop) {
    RegUseOrDef *list;
    BlockList *blocklist;
    PCode *instr;
    PCode *nextInstr;
    UInt32 *myvec;
    UseOrDef *def;
    int defID;
    int flag;
    PCodeBlock *block;

    myvec = oalloc(4 * ((number_of_Defs + 31) >> 5));
    do {
        flag = 0;
        for (blocklist = loop->blocks; blocklist; blocklist = blocklist->next) {
            block = blocklist->block;
            bitvectorcopy(myvec, usedefinfo[block->blockIndex].defvec8, number_of_Defs);
            for (instr = block->firstPCode; instr; instr = nextInstr) {
                nextInstr = instr->nextPCode;
                if (!(instr->flags & fPCodeFlag1) && instr->argCount) {
                    if (
                        !(instr->flags & (fPCodeFlag8 | fPCodeFlag20 | fIsVolatile | fSideEffects)) &&
                        isloopinvariant(instr, loop, myvec, 0, 0) &&
                        maymove(instr, loop)
                        ) {
                        moveinvariantcomputation(instr, loop);
                        flag = 1;
                    } else if (srawi_addze_isloopinvariant(instr, loop, myvec)) {
                        moveinvariantcomputation(instr, loop);
                        flag = 1;
                    }

                    for (def = &Defs[defID = instr->defID]; defID < number_of_Defs && def->pcode == instr; def++, defID++) {
                        if (def->v.kind == PCOp_REGISTER) {
                            for (list = reg_Defs[def->v.arg][def->v.u.reg]; list; list = list->next)
                                bitvectorclearbit(list->id, myvec);
                        } else if (def->v.kind == PCOp_MEMORY) {
                            if (def->v.arg == PCOpMemory0) {
                                for (list = findobjectusedef(def->v.u.object)->defs; list; list = list->next) {
                                    if (uniquely_aliases(instr, Defs[list->id].pcode))
                                        bitvectorclearbit(list->id, myvec);
                                }
                            }
                        } else {
                            CError_FATAL(1434);
                        }

                        bitvectorsetbit(defID, myvec);
                    }
                }
            }
        }
    } while (flag);
}

static void moveinvariantsfromloops(Loop *loop) {
    while (loop) {
        if (loop->children)
            moveinvariantsfromloops(loop->children);
        moveinvariantsfromloop(loop);
        loop = loop->nextSibling;
    }
}

void moveloopinvariantcode(void) {
    unswitchedinvariantcode = 0;
    movedloopinvariantcode = 0;
    if (loopsinflowgraph) {
        moveinvariantsfromloops(loopsinflowgraph);
        simpleunswitchloops(loopsinflowgraph);
    }
    freeoheap();
}