/*
 * Copyright 2009 Nicolai Haehnle.
 * Copyright 2012 Advanced Micro Devices, Inc.
 * Authors:
 *   Nicolai Haehnle
 *   Tom Stellard <thomas.stellard@amd.com>
 * SPDX-License-Identifier: MIT
 */

#include "radeon_dataflow.h"

#include "radeon_code.h"
#include "radeon_compiler.h"
#include "radeon_compiler_util.h"
#include "radeon_swizzle.h"

static unsigned int get_swizzle_split(struct radeon_compiler * c,
		struct rc_swizzle_split * split, struct rc_instruction * inst,
		unsigned src, unsigned * usemask)
{
	*usemask = 0;
	for(unsigned int chan = 0; chan < 4; ++chan) {
		if (GET_SWZ(inst->U.I.SrcReg[src].Swizzle, chan) != RC_SWIZZLE_UNUSED)
			*usemask |= 1 << chan;
	}

	c->SwizzleCaps->Split(inst->U.I.SrcReg[src], *usemask, split);
	return split->NumPhases;
}

static void rewrite_source(struct radeon_compiler * c,
		struct rc_instruction * inst, unsigned src)
{
	struct rc_swizzle_split split;
	unsigned int tempreg = rc_find_free_temporary(c);
	unsigned int usemask;

	get_swizzle_split(c, &split, inst, src, &usemask);

	for(unsigned int phase = 0; phase < split.NumPhases; ++phase) {
		struct rc_instruction * mov = rc_insert_new_instruction(c, inst->Prev);
		unsigned int masked_negate;

		mov->U.I.Opcode = RC_OPCODE_MOV;
		mov->U.I.DstReg.File = RC_FILE_TEMPORARY;
		mov->U.I.DstReg.Index = tempreg;
		mov->U.I.DstReg.WriteMask = split.Phase[phase];
		mov->U.I.SrcReg[0] = inst->U.I.SrcReg[src];
		mov->U.I.PreSub = inst->U.I.PreSub;

		for(unsigned int chan = 0; chan < 4; ++chan) {
			if (!GET_BIT(split.Phase[phase], chan))
				SET_SWZ(mov->U.I.SrcReg[0].Swizzle, chan, RC_SWIZZLE_UNUSED);
		}

		masked_negate = split.Phase[phase] & mov->U.I.SrcReg[0].Negate;
		if (masked_negate == 0)
			mov->U.I.SrcReg[0].Negate = 0;
		else if (masked_negate == split.Phase[phase])
			mov->U.I.SrcReg[0].Negate = RC_MASK_XYZW;

	}

	inst->U.I.SrcReg[src].File = RC_FILE_TEMPORARY;
	inst->U.I.SrcReg[src].Index = tempreg;
	inst->U.I.SrcReg[src].Swizzle = 0;
	inst->U.I.SrcReg[src].Negate = RC_MASK_NONE;
	inst->U.I.SrcReg[src].Abs = 0;
	for(unsigned int chan = 0; chan < 4; ++chan) {
		SET_SWZ(inst->U.I.SrcReg[src].Swizzle, chan,
				GET_BIT(usemask, chan) ? chan : RC_SWIZZLE_UNUSED);
	}
}

/**
 * This function will attempt to rewrite non-native swizzles that read from
 * immediate registers by rearranging the immediates to allow the
 * instruction to use native swizzles.
 */
static unsigned try_rewrite_constant(struct radeon_compiler *c,
					struct rc_src_register *reg)
{
	unsigned new_swizzle, chan, swz0, swz1, swz2, swz3, found_swizzle, swz;
	unsigned all_inline = 0;
	bool w_inline_constant = false;
	float imms[4] = {0.0f, 0.0f, 0.0f, 0.0f};

	if (!rc_src_reg_is_immediate(c, reg->File, reg->Index)) {
		/* The register does not contain immediates, but if all
		 * the swizzles are inline constants, we can still rewrite
		 * it. */

		new_swizzle = RC_SWIZZLE_XYZW;
		for (chan = 0 ; chan < 4; chan++) {
			unsigned swz = GET_SWZ(reg->Swizzle, chan);
			if (swz <= RC_SWIZZLE_W) {
				return 0;
			}
			if (swz == RC_SWIZZLE_UNUSED) {
				SET_SWZ(new_swizzle, chan, RC_SWIZZLE_UNUSED);
			}
		}
		all_inline = 1;
	} else {
		new_swizzle = reg->Swizzle;
	}

	swz = RC_SWIZZLE_UNUSED;
	found_swizzle = 1;
	/* Check if all channels have the same swizzle.  If they do we can skip
	 * the search for a native swizzle.  We only need to check the first
	 * three channels, because any swizzle is legal in the fourth channel.
	 */
	for (chan = 0; chan < 3; chan++) {
		unsigned chan_swz = GET_SWZ(reg->Swizzle, chan);
		if (chan_swz == RC_SWIZZLE_UNUSED) {
			continue;
		}
		if (swz == RC_SWIZZLE_UNUSED) {
			swz = chan_swz;
		} else if (swz != chan_swz) {
			found_swizzle = 0;
			break;
		}
	}

	/* Find a legal swizzle */

	/* This loop attempts to find a native swizzle where all the
	 * channels are different. */
	while (!found_swizzle && !all_inline) {
		swz0 = GET_SWZ(new_swizzle, 0);
		swz1 = GET_SWZ(new_swizzle, 1);
		swz2 = GET_SWZ(new_swizzle, 2);

		/* Swizzle .W. is never legal. */
		if (swz1 == RC_SWIZZLE_W ||
			swz1 == RC_SWIZZLE_UNUSED ||
			swz1 == RC_SWIZZLE_ZERO ||
			swz1 == RC_SWIZZLE_HALF ||
			swz1 == RC_SWIZZLE_ONE) {
			/* We chose Z, because there are two non-repeating
			 * swizzle combinations of the form .Z. There are
			 * only one combination each for .X. and .Y. */
			SET_SWZ(new_swizzle, 1, RC_SWIZZLE_Z);
			continue;
		}

		if (swz2 == RC_SWIZZLE_UNUSED) {
			/* We choose Y, because there are two non-repeating
			 * swizzle combinations of the form ..Y */
			SET_SWZ(new_swizzle, 2, RC_SWIZZLE_Y);
			continue;
		}

		switch (swz0) {
		/* X.. */
		case RC_SWIZZLE_X:
			/* Legal swizzles that start with X: XYZ, XXX */
			switch (swz1) {
			/* XX. */
			case RC_SWIZZLE_X:
				/*  The new swizzle will be:
				 *  ZXY (XX. => ZX. => ZXY) */
				SET_SWZ(new_swizzle, 0, RC_SWIZZLE_Z);
				break;
			/* XY. */
			case RC_SWIZZLE_Y:
				/* The new swizzle is XYZ */
				SET_SWZ(new_swizzle, 2, RC_SWIZZLE_Z);
				found_swizzle = 1;
				break;
			/* XZ. */
			case RC_SWIZZLE_Z:
				/* XZZ */
				if (swz2 == RC_SWIZZLE_Z) {
					/* The new swizzle is XYZ */
					SET_SWZ(new_swizzle, 1, RC_SWIZZLE_Y);
					found_swizzle = 1;
				} else { /* XZ[^Z] */
					/* The new swizzle will be:
					 * YZX (XZ. => YZ. => YZX) */
					SET_SWZ(new_swizzle, 0, RC_SWIZZLE_Y);
				}
				break;
			/* XW. Should have already been handled. */
			case RC_SWIZZLE_W:
				assert(0);
				break;
			}
			break;
		/* Y.. */
		case RC_SWIZZLE_Y:
			/* Legal swizzles that start with Y: YYY, YZX */
			switch (swz1) {
			/* YY. */
			case RC_SWIZZLE_Y:
				/* The new swizzle will be:
				 * XYZ (YY. => XY. => XYZ) */
				SET_SWZ(new_swizzle, 0, RC_SWIZZLE_X);
				break;
			/* YZ. */
			case RC_SWIZZLE_Z:
				/* The new swizzle is YZX */
				SET_SWZ(new_swizzle, 2, RC_SWIZZLE_X);
				found_swizzle = 1;
				break;
			/* YX. */
			case RC_SWIZZLE_X:
				/* YXX */
				if (swz2 == RC_SWIZZLE_X) {
					/*The new swizzle is YZX */
					SET_SWZ(new_swizzle, 1, RC_SWIZZLE_Z);
					found_swizzle = 1;
				} else { /* YX[^X] */
					/* The new swizzle will be:
					 * ZXY (YX. => ZX. -> ZXY) */
					SET_SWZ(new_swizzle, 0, RC_SWIZZLE_Z);
				}
				break;
			/* YW. Should have already been handled. */
			case RC_SWIZZLE_W:
				assert(0);
				break;
			}
			break;
		/* Z.. */
		case RC_SWIZZLE_Z:
			/* Legal swizzles that start with Z: ZZZ, ZXY */
			switch (swz1) {
			/* ZZ. */
			case RC_SWIZZLE_Z:
				/* The new swizzle will be:
				 * WZY (ZZ. => WZ. => WZY) */
				SET_SWZ(new_swizzle, 0, RC_SWIZZLE_W);
				break;
			/* ZX. */
			case RC_SWIZZLE_X:
				/* The new swizzle is ZXY */
				SET_SWZ(new_swizzle, 2, RC_SWIZZLE_Y);
				found_swizzle = 1;
				break;
			/* ZY. */
			case RC_SWIZZLE_Y:
				/* ZYY */
				if (swz2 == RC_SWIZZLE_Y) {
					/* The new swizzle is ZXY */
					SET_SWZ(new_swizzle, 1, RC_SWIZZLE_X);
					found_swizzle = 1;
				} else { /* ZY[^Y] */
					/* The new swizzle will be:
					 * XYZ (ZY. => XY. => XYZ) */
					SET_SWZ(new_swizzle, 0, RC_SWIZZLE_X);
				}
				break;
			/* ZW. Should have already been handled. */
			case RC_SWIZZLE_W:
				assert(0);
				break;
			}
			break;

		/* W.. */
		case RC_SWIZZLE_W:
			/* Legal swizzles that start with X: WWW, WZY */
			switch (swz1) {
			/* WW. Should have already been handled. */
			case RC_SWIZZLE_W:
				assert(0);
				break;
			/* WZ. */
			case RC_SWIZZLE_Z:
				/* The new swizzle will be WZY */
				SET_SWZ(new_swizzle, 2, RC_SWIZZLE_Y);
				found_swizzle = 1;
				break;
			/* WX. */
			case RC_SWIZZLE_X:
			/* WY. */
			case RC_SWIZZLE_Y:
				/* W[XY]Y */
				if (swz2 == RC_SWIZZLE_Y) {
					/* The new swizzle will be WZY */
					SET_SWZ(new_swizzle, 1, RC_SWIZZLE_Z);
					found_swizzle = 1;
				} else { /* W[XY][^Y] */
					/* The new swizzle will be:
					 * ZXY (WX. => XX. => ZX. => ZXY) or
					 * XYZ (WY. => XY. => XYZ)
					 */
					SET_SWZ(new_swizzle, 0, RC_SWIZZLE_X);
				}
				break;
			}
			break;
		/* U.. 0.. 1.. H..*/
		case RC_SWIZZLE_UNUSED:
		case RC_SWIZZLE_ZERO:
		case RC_SWIZZLE_ONE:
		case RC_SWIZZLE_HALF:
			SET_SWZ(new_swizzle, 0, RC_SWIZZLE_X);
			break;
		}
	}

	/* Handle the swizzle in the w channel. */
	swz3 = GET_SWZ(reg->Swizzle, 3);

	/* We can skip this if the swizzle in channel w is an inline constant. */
	if (is_swizzle_inline_constant(swz3)) {
		w_inline_constant = true;
	} else {
		for (chan = 0; chan < 3; chan++) {
			unsigned old_swz = GET_SWZ(reg->Swizzle, chan);
			unsigned new_swz = GET_SWZ(new_swizzle, chan);
			/* If the swizzle in the w channel is the same as the
			 * swizzle in any other channels, we need to rewrite it.
			 * For example:
			 * reg->Swizzle == XWZW
			 * new_swizzle  == XYZX
			 * Since the swizzle in the y channel is being
			 * rewritten from W -> Y we need to change the swizzle
			 * in the w channel from W -> Y as well.
			 */
			if (old_swz == swz3) {
				SET_SWZ(new_swizzle, 3,
						GET_SWZ(new_swizzle, chan));
				break;
			}

			/* The swizzle in channel w will be overwritten by one
			 * of the new swizzles. */
			if (new_swz == swz3) {
				/* Find an unused swizzle */
				unsigned i;
				unsigned used = 0;
				for (i = 0; i < 3; i++) {
					used |= 1 << GET_SWZ(new_swizzle, i);
				}
				for (i = 0; i < 4; i++) {
					if (used & (1 << i)) {
						continue;
					}
					SET_SWZ(new_swizzle, 3, i);
				}
			}
		}
	}

	for (chan = 0; chan < 4; chan++) {
		unsigned old_swz = GET_SWZ(reg->Swizzle, chan);
		unsigned new_swz = GET_SWZ(new_swizzle, chan);

		if (old_swz == RC_SWIZZLE_UNUSED) {
			continue;
		}

		/* We don't need to change the swizzle in channel w if it is
		 * an inline constant.  These are always legal in the w channel.
		 *
		 * Swizzles with a value > RC_SWIZZLE_W are inline constants.
		 */
		if (chan == 3 && w_inline_constant) {
			continue;
		}

		if (new_swz > RC_SWIZZLE_W) {
			rc_error(c, "Bad swizzle in try_rewrite_constant()");
			new_swz = RC_SWIZZLE_X;
		}

		switch (old_swz) {
		case RC_SWIZZLE_ZERO:
			imms[new_swz] = 0.0f;
			break;
		case RC_SWIZZLE_HALF:
			if (reg->Negate & (1 << chan)) {
				imms[new_swz] = -0.5f;
			} else {
				imms[new_swz] = 0.5f;
			}
			break;
		case RC_SWIZZLE_ONE:
			if (reg->Negate & (1 << chan)) {
				imms[new_swz] = -1.0f;
			} else {
				imms[new_swz] = 1.0f;
			}
			break;
		default:
			imms[new_swz] = rc_get_constant_value(c, reg->Index,
					reg->Swizzle, reg->Negate, chan);
		}
		SET_SWZ(reg->Swizzle, chan, new_swz);
	}
	reg->Index = rc_constants_add_immediate_vec4(&c->Program.Constants,
							imms);
	/* We need to set the register file to CONSTANT in case we are
	 * converting a non-constant register with constant swizzles (e.g.
	 * ONE, ZERO, HALF).
	 */
	reg->File = RC_FILE_CONSTANT;
	reg->Negate = w_inline_constant ? reg->Negate & (1 << 3) : 0;
	return 1;
}

/**
 * Set all channels not specified by writemaks to unused.
 */
static void clear_channels(struct rc_instruction * inst, unsigned writemask)
{
	inst->U.I.DstReg.WriteMask = writemask;
	for (unsigned chan = 0; chan < 4; chan++) {
		if (writemask & (1 << chan))
			continue;

		const struct rc_opcode_info * opcode =
					rc_get_opcode_info(inst->U.I.Opcode);
		for (unsigned src = 0; src < opcode->NumSrcRegs; src++) {
			SET_SWZ(inst->U.I.SrcReg[src].Swizzle, chan, RC_SWIZZLE_UNUSED);
		}
	}
	/* TODO: We could in theory add constant swizzles back as well,
	 * they will be all legal when we have just a single channel,
	 * to save some sources and help the pair scheduling later. */
}

static bool try_splitting_single_channel(struct radeon_compiler * c,
						struct rc_instruction * inst)
{
	for (unsigned chan = 0; chan < 3; chan++) {
		struct rc_instruction * new_inst;
		new_inst = rc_insert_new_instruction(c, inst);
		memcpy(&new_inst->U.I, &inst->U.I, sizeof(struct rc_sub_instruction));
		clear_channels(new_inst, inst->U.I.DstReg.WriteMask ^ (1 << chan));

		const struct rc_opcode_info * opcode =
			rc_get_opcode_info(new_inst->U.I.Opcode);
		bool valid_swizzles = true;

		for (unsigned src = 0; src < opcode->NumSrcRegs; ++src) {
			struct rc_src_register *reg = &new_inst->U.I.SrcReg[src];

			if (!c->SwizzleCaps->IsNative(new_inst->U.I.Opcode, *reg))
				valid_swizzles = false;
		}

		if (!valid_swizzles) {
			rc_remove_instruction(new_inst);
		} else {
			clear_channels(inst, 1 << chan);
			return true;
		}
	}
	return false;
}

static bool try_splitting_instruction(struct radeon_compiler * c,
					struct rc_instruction * inst)
{
	/* Adding more output instructions in FS is bad for performance. */
	if (inst->U.I.DstReg.File == RC_FILE_OUTPUT)
		return false;

	/* When only single channel of the swizzle is wrong, like xwzw,
	 * it is best to just split the single channel out.
	 */
	if (inst->U.I.DstReg.WriteMask == RC_MASK_XYZW ||
		inst->U.I.DstReg.WriteMask == RC_MASK_XYZ) {
		if (try_splitting_single_channel(c, inst))
			return true;
	}

	for (unsigned chan = 0; chan < 3; chan++) {
		if (!(inst->U.I.DstReg.WriteMask & (1 << chan)))
			continue;

		unsigned next_chan;
		for (next_chan = chan + 1; next_chan < 4; next_chan++) {
			if (!(inst->U.I.DstReg.WriteMask & (1 << next_chan)))
				continue;

			/* We don't want to split the last used x/y/z channel and the
			 * w channel. Pair scheduling might be able to put it back
			 * together, but we don't trust it that much.
			 *
			 * Next is W already, rewrite the original inst and we are done.
			 */
			if (next_chan == 3) {
				clear_channels(inst, (1 << chan) | (1 << next_chan));
				return true;
			}

			struct rc_instruction * new_inst;
			new_inst = rc_insert_new_instruction(c, inst->Prev);
			memcpy(&new_inst->U.I, &inst->U.I, sizeof(struct rc_sub_instruction));
			clear_channels(new_inst, 1 << chan);
			break;
		}

		/* No next chan */
		if (next_chan == 4) {
			clear_channels(inst, 1 << chan);
			return true;
		}
	}
	assert(0 && "Unreachable\n");
	return false;
}

void rc_dataflow_swizzles(struct radeon_compiler * c, void *user)
{
	struct rc_instruction * inst;

	for(inst = c->Program.Instructions.Next;
					inst != &c->Program.Instructions;
					inst = inst->Next) {
		const struct rc_opcode_info * opcode =
					rc_get_opcode_info(inst->U.I.Opcode);
		unsigned src, usemask;
		unsigned total_splits = 0;
		struct rc_swizzle_split split;

		/* If multiple sources needs splitting or some source needs to split
		 * too many times, it is actually better to just split the whole ALU
		 * instruction to separate channels instead of inserting extra movs.
		 */
		for (src = 0; src < opcode->NumSrcRegs; ++src) {
			/* Don't count invalid swizzles from immediates, we can just
			 * insert new immediates with the correct order later.
			 */
			if (rc_src_reg_is_immediate(c, inst->U.I.SrcReg[src].File,
							inst->U.I.SrcReg[src].Index)
				&& c->Program.Constants.Count < R300_PFS_NUM_CONST_REGS) {
				total_splits++;
			} else {
				total_splits += get_swizzle_split(c, &split, inst,
									src, &usemask);
			}
		}

		/* Even if there is only a single split, i.e., two extra movs, this still
		 * accounts to three instructions, the same as when we split
		 * the original instruction right away.
		 */
		if (total_splits > opcode->NumSrcRegs && opcode->IsComponentwise) {
			if (try_splitting_instruction(c, inst))
				continue;
		}

		/* For texturing or non-componentwise opcodes we do the old way
		 * of adding extra movs.
		 */
		for(src = 0; src < opcode->NumSrcRegs; ++src) {
			struct rc_src_register *reg = &inst->U.I.SrcReg[src];
			if (c->SwizzleCaps->IsNative(inst->U.I.Opcode, *reg)) {
				continue;
			}
			if (!c->is_r500 &&
			    c->Program.Constants.Count < R300_PFS_NUM_CONST_REGS &&
			    (!opcode->HasTexture && inst->U.I.Opcode != RC_OPCODE_KIL) &&
			    try_rewrite_constant(c, reg)) {
				continue;
			}
			rewrite_source(c, inst, src);
		}
	}
	if (c->Debug & RC_DBG_LOG)
		rc_constants_print(&c->Program.Constants, NULL);
}