[mesa.git] / src / gallium / drivers / r300 / compiler / radeon_dataflow.c

/*
 * Copyright (C) 2009 Nicolai Haehnle.
 * Copyright 2010 Tom Stellard <tstellar@gmail.com>
 *
 * All Rights Reserved.
 *
 * 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 (including the
 * next paragraph) 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 COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS 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 "radeon_dataflow.h"

#include "radeon_compiler.h"
#include "radeon_compiler_util.h"
#include "radeon_program.h"

struct read_write_mask_data {
        void * UserData;
        rc_read_write_mask_fn Cb;
};

static void reads_normal_callback(
        void * userdata,
        struct rc_instruction * fullinst,
        struct rc_src_register * src)
{
        struct read_write_mask_data * cb_data = userdata;
        unsigned int refmask = 0;
        unsigned int chan;
        for(chan = 0; chan < 4; chan++) {
                refmask |= 1 << GET_SWZ(src->Swizzle, chan);
        }
        refmask &= RC_MASK_XYZW;

        if (refmask) {
                cb_data->Cb(cb_data->UserData, fullinst, src->File,
                                                        src->Index, refmask);
        }

        if (refmask && src->RelAddr) {
                cb_data->Cb(cb_data->UserData, fullinst, RC_FILE_ADDRESS, 0,
                                                                RC_MASK_X);
        }
}

static void pair_get_src_refmasks(unsigned int * refmasks,
                                        struct rc_pair_instruction * inst,
                                        unsigned int swz, unsigned int src)
{
        if (swz >= 4)
                return;

        if (swz == RC_SWIZZLE_X || swz == RC_SWIZZLE_Y || swz == RC_SWIZZLE_Z) {
                if(src == RC_PAIR_PRESUB_SRC) {
                        unsigned int i;
                        int srcp_regs =
                                rc_presubtract_src_reg_count(
                                inst->RGB.Src[src].Index);
                        for(i = 0; i < srcp_regs; i++) {
                                refmasks[i] |= 1 << swz;
                        }
                }
                else {
                        refmasks[src] |= 1 << swz;
                }
        }

        if (swz == RC_SWIZZLE_W) {
                if (src == RC_PAIR_PRESUB_SRC) {
                        unsigned int i;
                        int srcp_regs = rc_presubtract_src_reg_count(
                                        inst->Alpha.Src[src].Index);
                        for(i = 0; i < srcp_regs; i++) {
                                refmasks[i] |= 1 << swz;
                        }
                }
                else {
                        refmasks[src] |= 1 << swz;
                }
        }
}

static void reads_pair(struct rc_instruction * fullinst, rc_read_write_mask_fn cb, void * userdata)
{
        struct rc_pair_instruction * inst = &fullinst->U.P;
        unsigned int refmasks[3] = { 0, 0, 0 };

        unsigned int arg;

        for(arg = 0; arg < 3; ++arg) {
                unsigned int chan;
                for(chan = 0; chan < 3; ++chan) {
                        unsigned int swz_rgb =
                                GET_SWZ(inst->RGB.Arg[arg].Swizzle, chan);
                        unsigned int swz_alpha =
                                GET_SWZ(inst->Alpha.Arg[arg].Swizzle, chan);
                        pair_get_src_refmasks(refmasks, inst, swz_rgb,
                                                inst->RGB.Arg[arg].Source);
                        pair_get_src_refmasks(refmasks, inst, swz_alpha,
                                                inst->Alpha.Arg[arg].Source);
                }
        }

        for(unsigned int src = 0; src < 3; ++src) {
                if (inst->RGB.Src[src].Used && (refmasks[src] & RC_MASK_XYZ))
                        cb(userdata, fullinst, inst->RGB.Src[src].File, inst->RGB.Src[src].Index,
                           refmasks[src] & RC_MASK_XYZ);

                if (inst->Alpha.Src[src].Used && (refmasks[src] & RC_MASK_W))
                        cb(userdata, fullinst, inst->Alpha.Src[src].File, inst->Alpha.Src[src].Index, RC_MASK_W);
        }
}

static void pair_sub_for_all_args(
        struct rc_instruction * fullinst,
        struct rc_pair_sub_instruction * sub,
        rc_pair_read_arg_fn cb,
        void * userdata)
{
        int i;
        const struct rc_opcode_info * info = rc_get_opcode_info(sub->Opcode);

        for(i = 0; i < info->NumSrcRegs; i++) {
                unsigned int src_type;

                src_type = rc_source_type_swz(sub->Arg[i].Swizzle);

                if (src_type == RC_SOURCE_NONE)
                        continue;

                if (sub->Arg[i].Source == RC_PAIR_PRESUB_SRC) {
                        unsigned int presub_type;
                        unsigned int presub_src_count;
                        struct rc_pair_instruction_source * src_array;
                        unsigned int j;

                        if (src_type & RC_SOURCE_RGB) {
                                presub_type = fullinst->
                                        U.P.RGB.Src[RC_PAIR_PRESUB_SRC].Index;
                                src_array = fullinst->U.P.RGB.Src;
                        } else {
                                presub_type = fullinst->
                                        U.P.Alpha.Src[RC_PAIR_PRESUB_SRC].Index;
                                src_array = fullinst->U.P.Alpha.Src;
                        }
                        presub_src_count
                                = rc_presubtract_src_reg_count(presub_type);
                        for(j = 0; j < presub_src_count; j++) {
                                cb(userdata, fullinst, &sub->Arg[i],
                                                                &src_array[j]);
                        }
                } else {
                        struct rc_pair_instruction_source * src =
                                rc_pair_get_src(&fullinst->U.P, &sub->Arg[i]);
                        if (src) {
                                cb(userdata, fullinst, &sub->Arg[i], src);
                        }
                }
        }
}

/* This function calls the callback function (cb) for each source used by
 * the instruction.
 * */
void rc_for_all_reads_src(
        struct rc_instruction * inst,
        rc_read_src_fn cb,
        void * userdata)
{
        const struct rc_opcode_info * opcode =
                                        rc_get_opcode_info(inst->U.I.Opcode);

        /* This function only works with normal instructions. */
        if (inst->Type != RC_INSTRUCTION_NORMAL) {
                assert(0);
                return;
        }

        for(unsigned int src = 0; src < opcode->NumSrcRegs; ++src) {

                if (inst->U.I.SrcReg[src].File == RC_FILE_NONE)
                        continue;

                if (inst->U.I.SrcReg[src].File == RC_FILE_PRESUB) {
                        unsigned int i;
                        unsigned int srcp_regs = rc_presubtract_src_reg_count(
                                                inst->U.I.PreSub.Opcode);
                        for( i = 0; i < srcp_regs; i++) {
                                cb(userdata, inst, &inst->U.I.PreSub.SrcReg[i]);
                        }
                } else {
                        cb(userdata, inst, &inst->U.I.SrcReg[src]);
                }
        }
}

/**
 * This function calls the callback function (cb) for each arg of the RGB and
 * alpha components.
 */
void rc_pair_for_all_reads_arg(
        struct rc_instruction * inst,
        rc_pair_read_arg_fn cb,
        void * userdata)
{
        /* This function only works with pair instructions. */
        if (inst->Type != RC_INSTRUCTION_PAIR) {
                assert(0);
                return;
        }

        pair_sub_for_all_args(inst, &inst->U.P.RGB, cb, userdata);
        pair_sub_for_all_args(inst, &inst->U.P.Alpha, cb, userdata);
}

/**
 * Calls a callback function for all register reads.
 *
 * This is conservative, i.e. if the same register is referenced multiple times,
 * the callback may also be called multiple times.
 * Also, the writemask of the instruction is not taken into account.
 */
void rc_for_all_reads_mask(struct rc_instruction * inst, rc_read_write_mask_fn cb, void * userdata)
{
        if (inst->Type == RC_INSTRUCTION_NORMAL) {
                struct read_write_mask_data cb_data;
                cb_data.UserData = userdata;
                cb_data.Cb = cb;

                rc_for_all_reads_src(inst, reads_normal_callback, &cb_data);
        } else {
                reads_pair(inst, cb, userdata);
        }
}



static void writes_normal(struct rc_instruction * fullinst, rc_read_write_mask_fn cb, void * userdata)
{
        struct rc_sub_instruction * inst = &fullinst->U.I;
        const struct rc_opcode_info * opcode = rc_get_opcode_info(inst->Opcode);

        if (opcode->HasDstReg && inst->DstReg.WriteMask)
                cb(userdata, fullinst, inst->DstReg.File, inst->DstReg.Index, inst->DstReg.WriteMask);

        if (inst->WriteALUResult)
                cb(userdata, fullinst, RC_FILE_SPECIAL, RC_SPECIAL_ALU_RESULT, RC_MASK_X);
}

static void writes_pair(struct rc_instruction * fullinst, rc_read_write_mask_fn cb, void * userdata)
{
        struct rc_pair_instruction * inst = &fullinst->U.P;

        if (inst->RGB.WriteMask)
                cb(userdata, fullinst, RC_FILE_TEMPORARY, inst->RGB.DestIndex, inst->RGB.WriteMask);

        if (inst->Alpha.WriteMask)
                cb(userdata, fullinst, RC_FILE_TEMPORARY, inst->Alpha.DestIndex, RC_MASK_W);

        if (inst->WriteALUResult)
                cb(userdata, fullinst, RC_FILE_SPECIAL, RC_SPECIAL_ALU_RESULT, RC_MASK_X);
}

/**
 * Calls a callback function for all register writes in the instruction,
 * reporting writemasks to the callback function.
 *
 * \warning Does not report output registers for paired instructions!
 */
void rc_for_all_writes_mask(struct rc_instruction * inst, rc_read_write_mask_fn cb, void * userdata)
{
        if (inst->Type == RC_INSTRUCTION_NORMAL) {
                writes_normal(inst, cb, userdata);
        } else {
                writes_pair(inst, cb, userdata);
        }
}


struct mask_to_chan_data {
        void * UserData;
        rc_read_write_chan_fn Fn;
};

static void mask_to_chan_cb(void * data, struct rc_instruction * inst,
                rc_register_file file, unsigned int index, unsigned int mask)
{
        struct mask_to_chan_data * d = data;
        for(unsigned int chan = 0; chan < 4; ++chan) {
                if (GET_BIT(mask, chan))
                        d->Fn(d->UserData, inst, file, index, chan);
        }
}

/**
 * Calls a callback function for all sourced register channels.
 *
 * This is conservative, i.e. channels may be called multiple times,
 * and the writemask of the instruction is not taken into account.
 */
void rc_for_all_reads_chan(struct rc_instruction * inst, rc_read_write_chan_fn cb, void * userdata)
{
        struct mask_to_chan_data d;
        d.UserData = userdata;
        d.Fn = cb;
        rc_for_all_reads_mask(inst, &mask_to_chan_cb, &d);
}

/**
 * Calls a callback function for all written register channels.
 *
 * \warning Does not report output registers for paired instructions!
 */
void rc_for_all_writes_chan(struct rc_instruction * inst, rc_read_write_chan_fn cb, void * userdata)
{
        struct mask_to_chan_data d;
        d.UserData = userdata;
        d.Fn = cb;
        rc_for_all_writes_mask(inst, &mask_to_chan_cb, &d);
}

static void remap_normal_instruction(struct rc_instruction * fullinst,
                rc_remap_register_fn cb, void * userdata)
{
        struct rc_sub_instruction * inst = &fullinst->U.I;
        const struct rc_opcode_info * opcode = rc_get_opcode_info(inst->Opcode);
        unsigned int remapped_presub = 0;

        if (opcode->HasDstReg) {
                rc_register_file file = inst->DstReg.File;
                unsigned int index = inst->DstReg.Index;

                cb(userdata, fullinst, &file, &index);

                inst->DstReg.File = file;
                inst->DstReg.Index = index;
        }

        for(unsigned int src = 0; src < opcode->NumSrcRegs; ++src) {
                rc_register_file file = inst->SrcReg[src].File;
                unsigned int index = inst->SrcReg[src].Index;

                if (file == RC_FILE_PRESUB) {
                        unsigned int i;
                        unsigned int srcp_srcs = rc_presubtract_src_reg_count(
                                                inst->PreSub.Opcode);
                        /* Make sure we only remap presubtract sources once in
                         * case more than one source register reads the
                         * presubtract result. */
                        if (remapped_presub)
                                continue;

                        for(i = 0; i < srcp_srcs; i++) {
                                file = inst->PreSub.SrcReg[i].File;
                                index = inst->PreSub.SrcReg[i].Index;
                                cb(userdata, fullinst, &file, &index);
                                inst->PreSub.SrcReg[i].File = file;
                                inst->PreSub.SrcReg[i].Index = index;
                        }
                        remapped_presub = 1;
                }
                else {
                        cb(userdata, fullinst, &file, &index);

                        inst->SrcReg[src].File = file;
                        inst->SrcReg[src].Index = index;
                }
        }
}

static void remap_pair_instruction(struct rc_instruction * fullinst,
                rc_remap_register_fn cb, void * userdata)
{
        struct rc_pair_instruction * inst = &fullinst->U.P;

        if (inst->RGB.WriteMask) {
                rc_register_file file = RC_FILE_TEMPORARY;
                unsigned int index = inst->RGB.DestIndex;

                cb(userdata, fullinst, &file, &index);

                inst->RGB.DestIndex = index;
        }

        if (inst->Alpha.WriteMask) {
                rc_register_file file = RC_FILE_TEMPORARY;
                unsigned int index = inst->Alpha.DestIndex;

                cb(userdata, fullinst, &file, &index);

                inst->Alpha.DestIndex = index;
        }

        for(unsigned int src = 0; src < 3; ++src) {
                if (inst->RGB.Src[src].Used) {
                        rc_register_file file = inst->RGB.Src[src].File;
                        unsigned int index = inst->RGB.Src[src].Index;

                        cb(userdata, fullinst, &file, &index);

                        inst->RGB.Src[src].File = file;
                        inst->RGB.Src[src].Index = index;
                }

                if (inst->Alpha.Src[src].Used) {
                        rc_register_file file = inst->Alpha.Src[src].File;
                        unsigned int index = inst->Alpha.Src[src].Index;

                        cb(userdata, fullinst, &file, &index);

                        inst->Alpha.Src[src].File = file;
                        inst->Alpha.Src[src].Index = index;
                }
        }
}


/**
 * Remap all register accesses according to the given function.
 * That is, call the function \p cb for each referenced register (both read and written)
 * and update the given instruction \p inst accordingly
 * if it modifies its \ref pfile and \ref pindex contents.
 */
void rc_remap_registers(struct rc_instruction * inst, rc_remap_register_fn cb, void * userdata)
{
        if (inst->Type == RC_INSTRUCTION_NORMAL)
                remap_normal_instruction(inst, cb, userdata);
        else
                remap_pair_instruction(inst, cb, userdata);
}

struct branch_write_mask {
        unsigned int IfWriteMask:4;
        unsigned int ElseWriteMask:4;
        unsigned int HasElse:1;
};

union get_readers_read_cb {
        rc_read_src_fn I;
        rc_pair_read_arg_fn P;
};

struct get_readers_callback_data {
        struct radeon_compiler * C;
        struct rc_reader_data * ReaderData;
        rc_read_src_fn ReadNormalCB;
        rc_pair_read_arg_fn ReadPairCB;
        rc_read_write_mask_fn WriteCB;
        rc_register_file DstFile;
        unsigned int DstIndex;
        unsigned int DstMask;
        unsigned int AliveWriteMask;
        /*  For convenience, this is indexed starting at 1 */
        struct branch_write_mask BranchMasks[R500_PFS_MAX_BRANCH_DEPTH_FULL + 1];
};

static struct rc_reader * add_reader(
        struct memory_pool * pool,
        struct rc_reader_data * data,
        struct rc_instruction * inst,
        unsigned int mask)
{
        struct rc_reader * new;
        memory_pool_array_reserve(pool, struct rc_reader, data->Readers,
                                data->ReaderCount, data->ReadersReserved, 1);
        new = &data->Readers[data->ReaderCount++];
        new->Inst = inst;
        new->WriteMask = mask;
        return new;
}

static void add_reader_normal(
        struct memory_pool * pool,
        struct rc_reader_data * data,
        struct rc_instruction * inst,
        unsigned int mask,
        struct rc_src_register * src)
{
        struct rc_reader * new = add_reader(pool, data, inst, mask);
        new->U.I.Src = src;
}


static void add_reader_pair(
        struct memory_pool * pool,
        struct rc_reader_data * data,
        struct rc_instruction * inst,
        unsigned int mask,
        struct rc_pair_instruction_arg * arg,
        struct rc_pair_instruction_source * src)
{
        struct rc_reader * new = add_reader(pool, data, inst, mask);
        new->U.P.Src = src;
        new->U.P.Arg = arg;
}

static unsigned int get_readers_read_callback(
        struct get_readers_callback_data * cb_data,
        unsigned int has_rel_addr,
        rc_register_file file,
        unsigned int index,
        unsigned int swizzle)
{
        unsigned int shared_mask, read_mask;

        if (has_rel_addr) {
                cb_data->ReaderData->Abort = 1;
                return RC_MASK_NONE;
        }

        shared_mask = rc_src_reads_dst_mask(file, index, swizzle,
                cb_data->DstFile, cb_data->DstIndex, cb_data->AliveWriteMask);

        if (shared_mask == RC_MASK_NONE)
                return shared_mask;

        /* If we make it this far, it means that this source reads from the
         * same register written to by d->ReaderData->Writer. */

        read_mask = rc_swizzle_to_writemask(swizzle);
        if (cb_data->ReaderData->AbortOnRead & read_mask) {
                cb_data->ReaderData->Abort = 1;
                return shared_mask;
        }

        if (cb_data->ReaderData->LoopDepth > 0) {
                cb_data->ReaderData->AbortOnWrite |=
                                (read_mask & cb_data->AliveWriteMask);
        }

        /* XXX The behavior in this case should be configurable. */
        if ((read_mask & cb_data->AliveWriteMask) != read_mask) {
                cb_data->ReaderData->Abort = 1;
                return shared_mask;
        }

        return shared_mask;
}

static void get_readers_pair_read_callback(
        void * userdata,
        struct rc_instruction * inst,
        struct rc_pair_instruction_arg * arg,
        struct rc_pair_instruction_source * src)
{
        unsigned int shared_mask;
        struct get_readers_callback_data * d = userdata;

        shared_mask = get_readers_read_callback(d,
                                0 /*Pair Instructions don't use RelAddr*/,
                                src->File, src->Index, arg->Swizzle);

        if (shared_mask == RC_MASK_NONE)
                return;

        if (d->ReadPairCB)
                d->ReadPairCB(d->ReaderData, inst, arg, src);

        if (d->ReaderData->ExitOnAbort && d->ReaderData->Abort)
                return;

        add_reader_pair(&d->C->Pool, d->ReaderData, inst, shared_mask, arg, src);
}

/**
 * This function is used by rc_get_readers_normal() to determine whether inst
 * is a reader of userdata->ReaderData->Writer
 */
static void get_readers_normal_read_callback(
        void * userdata,
        struct rc_instruction * inst,
        struct rc_src_register * src)
{
        struct get_readers_callback_data * d = userdata;
        unsigned int shared_mask;

        shared_mask = get_readers_read_callback(d,
                        src->RelAddr, src->File, src->Index, src->Swizzle);

        if (shared_mask == RC_MASK_NONE)
                return;
        /* The callback function could potentially clear d->ReaderData->Abort,
         * so we need to call it before we return. */
        if (d->ReadNormalCB)
                d->ReadNormalCB(d->ReaderData, inst, src);

        if (d->ReaderData->ExitOnAbort && d->ReaderData->Abort)
                return;

        add_reader_normal(&d->C->Pool, d->ReaderData, inst, shared_mask, src);
}

/**
 * This function is used by rc_get_readers_normal() to determine when
 * userdata->ReaderData->Writer is dead (i. e. All compontents of its
 * destination register have been overwritten by other instructions).
 */
static void get_readers_write_callback(
        void *userdata,
        struct rc_instruction * inst,
        rc_register_file file,
        unsigned int index,
        unsigned int mask)
{
        struct get_readers_callback_data * d = userdata;

        if (index == d->DstIndex && file == d->DstFile) {
                unsigned int shared_mask = mask & d->DstMask;
                d->ReaderData->AbortOnRead &= ~shared_mask;
                d->AliveWriteMask &= ~shared_mask;
                if (d->ReaderData->AbortOnWrite & shared_mask) {
                        d->ReaderData->Abort = 1;
                }
        }

        if(d->WriteCB)
                d->WriteCB(d->ReaderData, inst, file, index, mask);
}

static void push_branch_mask(
        struct get_readers_callback_data * d,
        unsigned int * branch_depth)
{
        (*branch_depth)++;
        if (*branch_depth > R500_PFS_MAX_BRANCH_DEPTH_FULL) {
                d->ReaderData->Abort = 1;
                return;
        }
        d->BranchMasks[*branch_depth].IfWriteMask =
                                        d->AliveWriteMask;
}

static void pop_branch_mask(
        struct get_readers_callback_data * d,
        unsigned int * branch_depth)
{
        struct branch_write_mask * masks = &d->BranchMasks[*branch_depth];

        if (masks->HasElse) {
                /* Abort on read for components that were written in the IF
                 * block. */
                d->ReaderData->AbortOnRead |=
                                masks->IfWriteMask & ~masks->ElseWriteMask;
                /* Abort on read for components that were written in the ELSE
                 * block. */
                d->ReaderData->AbortOnRead |=
                                masks->ElseWriteMask & ~d->AliveWriteMask;

                d->AliveWriteMask = masks->IfWriteMask
                        ^ ((masks->IfWriteMask ^ masks->ElseWriteMask)
                        & (masks->IfWriteMask ^ d->AliveWriteMask));
        } else {
                d->ReaderData->AbortOnRead |=
                                masks->IfWriteMask & ~d->AliveWriteMask;
                d->AliveWriteMask = masks->IfWriteMask;

        }
        memset(masks, 0, sizeof(struct branch_write_mask));
        (*branch_depth)--;
}

static void get_readers_for_single_write(
        void * userdata,
        struct rc_instruction * writer,
        rc_register_file dst_file,
        unsigned int dst_index,
        unsigned int dst_mask)
{
        struct rc_instruction * tmp;
        unsigned int branch_depth = 0;
        struct rc_instruction * endloop = NULL;
        unsigned int abort_on_read_at_endloop = 0;
        struct get_readers_callback_data * d = userdata;

        d->ReaderData->Writer = writer;
        d->ReaderData->AbortOnRead = 0;
        d->ReaderData->AbortOnWrite = 0;
        d->ReaderData->LoopDepth = 0;
        d->ReaderData->InElse = 0;
        d->DstFile = dst_file;
        d->DstIndex = dst_index;
        d->DstMask = dst_mask;
        d->AliveWriteMask = dst_mask;
        memset(d->BranchMasks, 0, sizeof(d->BranchMasks));

        if (!dst_mask)
                return;

        for(tmp = writer->Next; tmp != &d->C->Program.Instructions;
                                                        tmp = tmp->Next){
                rc_opcode opcode = rc_get_flow_control_inst(tmp);
                switch(opcode) {
                case RC_OPCODE_BGNLOOP:
                        d->ReaderData->LoopDepth++;
                        push_branch_mask(d, &branch_depth);
                        break;
                case RC_OPCODE_ENDLOOP:
                        if (d->ReaderData->LoopDepth > 0) {
                                d->ReaderData->LoopDepth--;
                                if (d->ReaderData->LoopDepth == 0) {
                                        d->ReaderData->AbortOnWrite = 0;
                                }
                                pop_branch_mask(d, &branch_depth);
                        } else {
                                /* Here we have reached an ENDLOOP without
                                 * seeing its BGNLOOP.  These means that
                                 * the writer was written inside of a loop,
                                 * so it could have readers that are above it
                                 * (i.e. they have a lower IP).  To find these
                                 * readers we jump to the BGNLOOP instruction
                                 * and check each instruction until we get
                                 * back to the writer.
                                 */
                                endloop = tmp;
                                tmp = rc_match_endloop(tmp);
                                if (!tmp) {
                                        rc_error(d->C, "Failed to match endloop.\n");
                                        d->ReaderData->Abort = 1;
                                        return;
                                }
                                abort_on_read_at_endloop = d->ReaderData->AbortOnRead;
                                d->ReaderData->AbortOnRead |= d->AliveWriteMask;
                                continue;
                        }
                        break;
                case RC_OPCODE_IF:
                        push_branch_mask(d, &branch_depth);
                        break;
                case RC_OPCODE_ELSE:
                        if (branch_depth == 0) {
                                d->ReaderData->InElse = 1;
                        } else {
                                unsigned int temp_mask = d->AliveWriteMask;
                                d->AliveWriteMask =
                                        d->BranchMasks[branch_depth].IfWriteMask;
                                d->BranchMasks[branch_depth].ElseWriteMask =
                                                                temp_mask;
                                d->BranchMasks[branch_depth].HasElse = 1;
                        }
                        break;
                case RC_OPCODE_ENDIF:
                        if (branch_depth == 0) {
                                d->ReaderData->AbortOnRead = d->AliveWriteMask;
                                d->ReaderData->InElse = 0;
                        }
                        else {
                                pop_branch_mask(d, &branch_depth);
                        }
                        break;
                default:
                        break;
                }

                if (d->ReaderData->InElse)
                        continue;

                if (tmp->Type == RC_INSTRUCTION_NORMAL) {
                        rc_for_all_reads_src(tmp,
                                get_readers_normal_read_callback, d);
                } else {
                        rc_pair_for_all_reads_arg(tmp,
                                get_readers_pair_read_callback, d);
                }

                /* This can happen when we jump from an ENDLOOP to BGNLOOP */
                if (tmp == writer) {
                        tmp = endloop;
                        endloop = NULL;
                        d->ReaderData->AbortOnRead = abort_on_read_at_endloop;
                        continue;
                }
                rc_for_all_writes_mask(tmp, get_readers_write_callback, d);

                if (d->ReaderData->ExitOnAbort && d->ReaderData->Abort)
                        return;

                if (branch_depth == 0 && !d->AliveWriteMask)
                        return;
        }
}

static void init_get_readers_callback_data(
        struct get_readers_callback_data * d,
        struct rc_reader_data * reader_data,
        struct radeon_compiler * c,
        rc_read_src_fn read_normal_cb,
        rc_pair_read_arg_fn read_pair_cb,
        rc_read_write_mask_fn write_cb)
{
        reader_data->Abort = 0;
        reader_data->ReaderCount = 0;
        reader_data->ReadersReserved = 0;
        reader_data->Readers = NULL;

        d->C = c;
        d->ReaderData = reader_data;
        d->ReadNormalCB = read_normal_cb;
        d->ReadPairCB = read_pair_cb;
        d->WriteCB = write_cb;
}

/**
 * This function will create a list of readers via the rc_reader_data struct.
 * This function will abort (set the flag data->Abort) and return if it
 * encounters an instruction that reads from @param writer and also a different
 * instruction.  Here are some examples:
 *
 * writer = instruction 0;
 * 0 MOV TEMP[0].xy, TEMP[1].xy
 * 1 MOV TEMP[0].zw, TEMP[2].xy
 * 2 MOV TEMP[3], TEMP[0]
 * The Abort flag will be set on instruction 2, because it reads values written
 * by instructions 0 and 1.
 *
 * writer = instruction 1;
 * 0 IF TEMP[0].x
 * 1 MOV TEMP[1], TEMP[2]
 * 2 ELSE
 * 3 MOV TEMP[1], TEMP[2]
 * 4 ENDIF
 * 5 MOV TEMP[3], TEMP[1]
 * The Abort flag will be set on instruction 5, because it could read from the
 * value written by either instruction 1 or 3, depending on the jump decision
 * made at instruction 0.
 *
 * writer = instruction 0;
 * 0 MOV TEMP[0], TEMP[1]
 * 2 BGNLOOP
 * 3 ADD TEMP[0], TEMP[0], none.1
 * 4 ENDLOOP
 * The Abort flag will be set on instruction 3, because in the first iteration
 * of the loop it reads the value written by instruction 0 and in all other
 * iterations it reads the value written by instruction 3.
 *
 * @param read_cb This function will be called for for every instruction that
 * has been determined to be a reader of writer.
 * @param write_cb This function will be called for every instruction after
 * writer.
 */
void rc_get_readers(
        struct radeon_compiler * c,
        struct rc_instruction * writer,
        struct rc_reader_data * data,
        rc_read_src_fn read_normal_cb,
        rc_pair_read_arg_fn read_pair_cb,
        rc_read_write_mask_fn write_cb)
{
        struct get_readers_callback_data d;

        init_get_readers_callback_data(&d, data, c, read_normal_cb,
                                                read_pair_cb, write_cb);

        rc_for_all_writes_mask(writer, get_readers_for_single_write, &d);
}

void rc_get_readers_sub(
        struct radeon_compiler * c,
        struct rc_instruction * writer,
        struct rc_pair_sub_instruction * sub_writer,
        struct rc_reader_data * data,
        rc_read_src_fn read_normal_cb,
        rc_pair_read_arg_fn read_pair_cb,
        rc_read_write_mask_fn write_cb)
{
        struct get_readers_callback_data d;

        init_get_readers_callback_data(&d, data, c, read_normal_cb,
                                                read_pair_cb, write_cb);

        if (sub_writer->WriteMask) {
                get_readers_for_single_write(&d, writer, RC_FILE_TEMPORARY,
                        sub_writer->DestIndex, sub_writer->WriteMask);
        }
}