src/compiler/nir/nir.h

/*
 * Copyright © 2014 Connor Abbott
 *
 * 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 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 * Authors:
 *    Connor Abbott (cwabbott0@gmail.com)
 *
 */

#pragma once

#include "util/hash_table.h"
#include "compiler/glsl/list.h"
#include "GL/gl.h" /* GLenum */
#include "util/list.h"
#include "util/ralloc.h"
#include "util/set.h"
#include "util/bitset.h"
#include "util/macros.h"
#include "compiler/nir_types.h"
#include "compiler/shader_enums.h"
#include "compiler/shader_info.h"
#include <stdio.h>

#include "nir_opcodes.h"

#ifdef __cplusplus
extern "C" {
#endif

struct gl_program;
struct gl_shader_program;

#define NIR_FALSE 0u
#define NIR_TRUE (~0u)

/** Defines a cast function
 *
 * This macro defines a cast function from in_type to out_type where
 * out_type is some structure type that contains a field of type out_type.
 *
 * Note that you have to be a bit careful as the generated cast function
 * destroys constness.
 */
#define NIR_DEFINE_CAST(name, in_type, out_type, field, \
                        type_field, type_value)         \
static inline out_type *                                \
name(const in_type *parent)                             \
{                                                       \
   assert(parent && parent->type_field == type_value);  \
   return exec_node_data(out_type, parent, field);      \
}

struct nir_function;
struct nir_shader;
struct nir_instr;


/**
 * Description of built-in state associated with a uniform
 *
 * \sa nir_variable::state_slots
 */
typedef struct {
   int tokens[5];
   int swizzle;
} nir_state_slot;

typedef enum {
   nir_var_shader_in       = (1 << 0),
   nir_var_shader_out      = (1 << 1),
   nir_var_global          = (1 << 2),
   nir_var_local           = (1 << 3),
   nir_var_uniform         = (1 << 4),
   nir_var_shader_storage  = (1 << 5),
   nir_var_system_value    = (1 << 6),
   nir_var_param           = (1 << 7),
   nir_var_shared          = (1 << 8),
   nir_var_all             = ~0,
} nir_variable_mode;


typedef union {
   float f32[4];
   double f64[4];
   int32_t i32[4];
   uint32_t u32[4];
   int64_t i64[4];
   uint64_t u64[4];
} nir_const_value;

typedef struct nir_constant {
   /**
    * Value of the constant.
    *
    * The field used to back the values supplied by the constant is determined
    * by the type associated with the \c nir_variable.  Constants may be
    * scalars, vectors, or matrices.
    */
   nir_const_value values[4];

   /* we could get this from the var->type but makes clone *much* easier to
    * not have to care about the type.
    */
   unsigned num_elements;

   /* Array elements / Structure Fields */
   struct nir_constant **elements;
} nir_constant;

/**
 * \brief Layout qualifiers for gl_FragDepth.
 *
 * The AMD/ARB_conservative_depth extensions allow gl_FragDepth to be redeclared
 * with a layout qualifier.
 */
typedef enum {
    nir_depth_layout_none, /**< No depth layout is specified. */
    nir_depth_layout_any,
    nir_depth_layout_greater,
    nir_depth_layout_less,
    nir_depth_layout_unchanged
} nir_depth_layout;

/**
 * Either a uniform, global variable, shader input, or shader output. Based on
 * ir_variable - it should be easy to translate between the two.
 */

typedef struct nir_variable {
   struct exec_node node;

   /**
    * Declared type of the variable
    */
   const struct glsl_type *type;

   /**
    * Declared name of the variable
    */
   char *name;

   struct nir_variable_data {
      /**
       * Storage class of the variable.
       *
       * \sa nir_variable_mode
       */
      nir_variable_mode mode;

      /**
       * Is the variable read-only?
       *
       * This is set for variables declared as \c const, shader inputs,
       * and uniforms.
       */
      unsigned read_only:1;
      unsigned centroid:1;
      unsigned sample:1;
      unsigned patch:1;
      unsigned invariant:1;

      /**
       * Interpolation mode for shader inputs / outputs
       *
       * \sa glsl_interp_mode
       */
      unsigned interpolation:2;

      /**
       * \name ARB_fragment_coord_conventions
       * @{
       */
      unsigned origin_upper_left:1;
      unsigned pixel_center_integer:1;
      /*@}*/

      /**
       * If non-zero, then this variable may be packed along with other variables
       * into a single varying slot, so this offset should be applied when
       * accessing components.  For example, an offset of 1 means that the x
       * component of this variable is actually stored in component y of the
       * location specified by \c location.
       */
      unsigned location_frac:2;

      /**
       * If true, this variable represents an array of scalars that should
       * be tightly packed.  In other words, consecutive array elements
       * should be stored one component apart, rather than one slot apart.
       */
      bool compact:1;

      /**
       * Whether this is a fragment shader output implicitly initialized with
       * the previous contents of the specified render target at the
       * framebuffer location corresponding to this shader invocation.
       */
      unsigned fb_fetch_output:1;

      /**
       * \brief Layout qualifier for gl_FragDepth.
       *
       * This is not equal to \c ir_depth_layout_none if and only if this
       * variable is \c gl_FragDepth and a layout qualifier is specified.
       */
      nir_depth_layout depth_layout;

      /**
       * Storage location of the base of this variable
       *
       * The precise meaning of this field depends on the nature of the variable.
       *
       *   - Vertex shader input: one of the values from \c gl_vert_attrib.
       *   - Vertex shader output: one of the values from \c gl_varying_slot.
       *   - Geometry shader input: one of the values from \c gl_varying_slot.
       *   - Geometry shader output: one of the values from \c gl_varying_slot.
       *   - Fragment shader input: one of the values from \c gl_varying_slot.
       *   - Fragment shader output: one of the values from \c gl_frag_result.
       *   - Uniforms: Per-stage uniform slot number for default uniform block.
       *   - Uniforms: Index within the uniform block definition for UBO members.
       *   - Non-UBO Uniforms: uniform slot number.
       *   - Other: This field is not currently used.
       *
       * If the variable is a uniform, shader input, or shader output, and the
       * slot has not been assigned, the value will be -1.
       */
      int location;

      /**
       * The actual location of the variable in the IR. Only valid for inputs
       * and outputs.
       */
      unsigned int driver_location;

      /**
       * output index for dual source blending.
       */
      int index;

      /**
       * Descriptor set binding for sampler or UBO.
       */
      int descriptor_set;

      /**
       * Initial binding point for a sampler or UBO.
       *
       * For array types, this represents the binding point for the first element.
       */
      int binding;

      /**
       * Location an atomic counter is stored at.
       */
      unsigned offset;

      /**
       * ARB_shader_image_load_store qualifiers.
       */
      struct {
         bool read_only; /**< "readonly" qualifier. */
         bool write_only; /**< "writeonly" qualifier. */
         bool coherent;
         bool _volatile;
         bool restrict_flag;

         /** Image internal format if specified explicitly, otherwise GL_NONE. */
         GLenum format;
      } image;
   } data;

   /**
    * Built-in state that backs this uniform
    *
    * Once set at variable creation, \c state_slots must remain invariant.
    * This is because, ideally, this array would be shared by all clones of
    * this variable in the IR tree.  In other words, we'd really like for it
    * to be a fly-weight.
    *
    * If the variable is not a uniform, \c num_state_slots will be zero and
    * \c state_slots will be \c NULL.
    */
   /*@{*/
   unsigned num_state_slots;    /**< Number of state slots used */
   nir_state_slot *state_slots;  /**< State descriptors. */
   /*@}*/

   /**
    * Constant expression assigned in the initializer of the variable
    *
    * This field should only be used temporarily by creators of NIR shaders
    * and then lower_constant_initializers can be used to get rid of them.
    * Most of the rest of NIR ignores this field or asserts that it's NULL.
    */
   nir_constant *constant_initializer;

   /**
    * For variables that are in an interface block or are an instance of an
    * interface block, this is the \c GLSL_TYPE_INTERFACE type for that block.
    *
    * \sa ir_variable::location
    */
   const struct glsl_type *interface_type;
} nir_variable;

#define nir_foreach_variable(var, var_list) \
   foreach_list_typed(nir_variable, var, node, var_list)

#define nir_foreach_variable_safe(var, var_list) \
   foreach_list_typed_safe(nir_variable, var, node, var_list)

static inline bool
nir_variable_is_global(const nir_variable *var)
{
   return var->data.mode != nir_var_local && var->data.mode != nir_var_param;
}

typedef struct nir_register {
   struct exec_node node;

   unsigned num_components; /** < number of vector components */
   unsigned num_array_elems; /** < size of array (0 for no array) */

   /* The bit-size of each channel; must be one of 8, 16, 32, or 64 */
   uint8_t bit_size;

   /** generic register index. */
   unsigned index;

   /** only for debug purposes, can be NULL */
   const char *name;

   /** whether this register is local (per-function) or global (per-shader) */
   bool is_global;

   /**
    * If this flag is set to true, then accessing channels >= num_components
    * is well-defined, and simply spills over to the next array element. This
    * is useful for backends that can do per-component accessing, in
    * particular scalar backends. By setting this flag and making
    * num_components equal to 1, structures can be packed tightly into
    * registers and then registers can be accessed per-component to get to
    * each structure member, even if it crosses vec4 boundaries.
    */
   bool is_packed;

   /** set of nir_src's where this register is used (read from) */
   struct list_head uses;

   /** set of nir_dest's where this register is defined (written to) */
   struct list_head defs;

   /** set of nir_if's where this register is used as a condition */
   struct list_head if_uses;
} nir_register;

typedef enum {
   nir_instr_type_alu,
   nir_instr_type_call,
   nir_instr_type_tex,
   nir_instr_type_intrinsic,
   nir_instr_type_load_const,
   nir_instr_type_jump,
   nir_instr_type_ssa_undef,
   nir_instr_type_phi,
   nir_instr_type_parallel_copy,
} nir_instr_type;

typedef struct nir_instr {
   struct exec_node node;
   nir_instr_type type;
   struct nir_block *block;

   /** generic instruction index. */
   unsigned index;

   /* A temporary for optimization and analysis passes to use for storing
    * flags.  For instance, DCE uses this to store the "dead/live" info.
    */
   uint8_t pass_flags;
} nir_instr;

static inline nir_instr *
nir_instr_next(nir_instr *instr)
{
   struct exec_node *next = exec_node_get_next(&instr->node);
   if (exec_node_is_tail_sentinel(next))
      return NULL;
   else
      return exec_node_data(nir_instr, next, node);
}

static inline nir_instr *
nir_instr_prev(nir_instr *instr)
{
   struct exec_node *prev = exec_node_get_prev(&instr->node);
   if (exec_node_is_head_sentinel(prev))
      return NULL;
   else
      return exec_node_data(nir_instr, prev, node);
}

static inline bool
nir_instr_is_first(nir_instr *instr)
{
   return exec_node_is_head_sentinel(exec_node_get_prev(&instr->node));
}

static inline bool
nir_instr_is_last(nir_instr *instr)
{
   return exec_node_is_tail_sentinel(exec_node_get_next(&instr->node));
}

typedef struct nir_ssa_def {
   /** for debugging only, can be NULL */
   const char* name;

   /** generic SSA definition index. */
   unsigned index;

   /** Index into the live_in and live_out bitfields */
   unsigned live_index;

   nir_instr *parent_instr;

   /** set of nir_instr's where this register is used (read from) */
   struct list_head uses;

   /** set of nir_if's where this register is used as a condition */
   struct list_head if_uses;

   uint8_t num_components;

   /* The bit-size of each channel; must be one of 8, 16, 32, or 64 */
   uint8_t bit_size;
} nir_ssa_def;

struct nir_src;

typedef struct {
   nir_register *reg;
   struct nir_src *indirect; /** < NULL for no indirect offset */
   unsigned base_offset;

   /* TODO use-def chain goes here */
} nir_reg_src;

typedef struct {
   nir_instr *parent_instr;
   struct list_head def_link;

   nir_register *reg;
   struct nir_src *indirect; /** < NULL for no indirect offset */
   unsigned base_offset;

   /* TODO def-use chain goes here */
} nir_reg_dest;

struct nir_if;

typedef struct nir_src {
   union {
      nir_instr *parent_instr;
      struct nir_if *parent_if;
   };

   struct list_head use_link;

   union {
      nir_reg_src reg;
      nir_ssa_def *ssa;
   };

   bool is_ssa;
} nir_src;

static inline nir_src
nir_src_init(void)
{
   nir_src src = { { NULL } };
   return src;
}

#define NIR_SRC_INIT nir_src_init()

#define nir_foreach_use(src, reg_or_ssa_def) \
   list_for_each_entry(nir_src, src, &(reg_or_ssa_def)->uses, use_link)

#define nir_foreach_use_safe(src, reg_or_ssa_def) \
   list_for_each_entry_safe(nir_src, src, &(reg_or_ssa_def)->uses, use_link)

#define nir_foreach_if_use(src, reg_or_ssa_def) \
   list_for_each_entry(nir_src, src, &(reg_or_ssa_def)->if_uses, use_link)

#define nir_foreach_if_use_safe(src, reg_or_ssa_def) \
   list_for_each_entry_safe(nir_src, src, &(reg_or_ssa_def)->if_uses, use_link)

typedef struct {
   union {
      nir_reg_dest reg;
      nir_ssa_def ssa;
   };

   bool is_ssa;
} nir_dest;

static inline nir_dest
nir_dest_init(void)
{
   nir_dest dest = { { { NULL } } };
   return dest;
}

#define NIR_DEST_INIT nir_dest_init()

#define nir_foreach_def(dest, reg) \
   list_for_each_entry(nir_dest, dest, &(reg)->defs, reg.def_link)

#define nir_foreach_def_safe(dest, reg) \
   list_for_each_entry_safe(nir_dest, dest, &(reg)->defs, reg.def_link)

static inline nir_src
nir_src_for_ssa(nir_ssa_def *def)
{
   nir_src src = NIR_SRC_INIT;

   src.is_ssa = true;
   src.ssa = def;

   return src;
}

static inline nir_src
nir_src_for_reg(nir_register *reg)
{
   nir_src src = NIR_SRC_INIT;

   src.is_ssa = false;
   src.reg.reg = reg;
   src.reg.indirect = NULL;
   src.reg.base_offset = 0;

   return src;
}

static inline nir_dest
nir_dest_for_reg(nir_register *reg)
{
   nir_dest dest = NIR_DEST_INIT;

   dest.reg.reg = reg;

   return dest;
}

static inline unsigned
nir_src_bit_size(nir_src src)
{
   return src.is_ssa ? src.ssa->bit_size : src.reg.reg->bit_size;
}

static inline unsigned
nir_dest_bit_size(nir_dest dest)
{
   return dest.is_ssa ? dest.ssa.bit_size : dest.reg.reg->bit_size;
}

void nir_src_copy(nir_src *dest, const nir_src *src, void *instr_or_if);
void nir_dest_copy(nir_dest *dest, const nir_dest *src, nir_instr *instr);

typedef struct {
   nir_src src;

   /**
    * \name input modifiers
    */
   /*@{*/
   /**
    * For inputs interpreted as floating point, flips the sign bit. For
    * inputs interpreted as integers, performs the two's complement negation.
    */
   bool negate;

   /**
    * Clears the sign bit for floating point values, and computes the integer
    * absolute value for integers. Note that the negate modifier acts after
    * the absolute value modifier, therefore if both are set then all inputs
    * will become negative.
    */
   bool abs;
   /*@}*/

   /**
    * For each input component, says which component of the register it is
    * chosen from. Note that which elements of the swizzle are used and which
    * are ignored are based on the write mask for most opcodes - for example,
    * a statement like "foo.xzw = bar.zyx" would have a writemask of 1101b and
    * a swizzle of {2, x, 1, 0} where x means "don't care."
    */
   uint8_t swizzle[4];
} nir_alu_src;

typedef struct {
   nir_dest dest;

   /**
    * \name saturate output modifier
    *
    * Only valid for opcodes that output floating-point numbers. Clamps the
    * output to between 0.0 and 1.0 inclusive.
    */

   bool saturate;

   unsigned write_mask : 4; /* ignored if dest.is_ssa is true */
} nir_alu_dest;

typedef enum {
   nir_type_invalid = 0, /* Not a valid type */
   nir_type_float,
   nir_type_int,
   nir_type_uint,
   nir_type_bool,
   nir_type_bool32 =    32 | nir_type_bool,
   nir_type_int8 =      8  | nir_type_int,
   nir_type_int16 =     16 | nir_type_int,
   nir_type_int32 =     32 | nir_type_int,
   nir_type_int64 =     64 | nir_type_int,
   nir_type_uint8 =     8  | nir_type_uint,
   nir_type_uint16 =    16 | nir_type_uint,
   nir_type_uint32 =    32 | nir_type_uint,
   nir_type_uint64 =    64 | nir_type_uint,
   nir_type_float16 =   16 | nir_type_float,
   nir_type_float32 =   32 | nir_type_float,
   nir_type_float64 =   64 | nir_type_float,
} nir_alu_type;

#define NIR_ALU_TYPE_SIZE_MASK 0xfffffff8
#define NIR_ALU_TYPE_BASE_TYPE_MASK 0x00000007

static inline unsigned
nir_alu_type_get_type_size(nir_alu_type type)
{
   return type & NIR_ALU_TYPE_SIZE_MASK;
}

static inline unsigned
nir_alu_type_get_base_type(nir_alu_type type)
{
   return type & NIR_ALU_TYPE_BASE_TYPE_MASK;
}

typedef enum {
   NIR_OP_IS_COMMUTATIVE = (1 << 0),
   NIR_OP_IS_ASSOCIATIVE = (1 << 1),
} nir_op_algebraic_property;

typedef struct {
   const char *name;

   unsigned num_inputs;

   /**
    * The number of components in the output
    *
    * If non-zero, this is the size of the output and input sizes are
    * explicitly given; swizzle and writemask are still in effect, but if
    * the output component is masked out, then the input component may
    * still be in use.
    *
    * If zero, the opcode acts in the standard, per-component manner; the
    * operation is performed on each component (except the ones that are
    * masked out) with the input being taken from the input swizzle for
    * that component.
    *
    * The size of some of the inputs may be given (i.e. non-zero) even
    * though output_size is zero; in that case, the inputs with a zero
    * size act per-component, while the inputs with non-zero size don't.
    */
   unsigned output_size;

   /**
    * The type of vector that the instruction outputs. Note that the
    * staurate modifier is only allowed on outputs with the float type.
    */

   nir_alu_type output_type;

   /**
    * The number of components in each input
    */
   unsigned input_sizes[4];

   /**
    * The type of vector that each input takes. Note that negate and
    * absolute value are only allowed on inputs with int or float type and
    * behave differently on the two.
    */
   nir_alu_type input_types[4];

   nir_op_algebraic_property algebraic_properties;
} nir_op_info;

extern const nir_op_info nir_op_infos[nir_num_opcodes];

typedef struct nir_alu_instr {
   nir_instr instr;
   nir_op op;

   /** Indicates that this ALU instruction generates an exact value
    *
    * This is kind of a mixture of GLSL "precise" and "invariant" and not
    * really equivalent to either.  This indicates that the value generated by
    * this operation is high-precision and any code transformations that touch
    * it must ensure that the resulting value is bit-for-bit identical to the
    * original.
    */
   bool exact;

   nir_alu_dest dest;
   nir_alu_src src[];
} nir_alu_instr;

void nir_alu_src_copy(nir_alu_src *dest, const nir_alu_src *src,
                      nir_alu_instr *instr);
void nir_alu_dest_copy(nir_alu_dest *dest, const nir_alu_dest *src,
                       nir_alu_instr *instr);

/* is this source channel used? */
static inline bool
nir_alu_instr_channel_used(nir_alu_instr *instr, unsigned src, unsigned channel)
{
   if (nir_op_infos[instr->op].input_sizes[src] > 0)
      return channel < nir_op_infos[instr->op].input_sizes[src];

   return (instr->dest.write_mask >> channel) & 1;
}

/*
 * For instructions whose destinations are SSA, get the number of channels
 * used for a source
 */
static inline unsigned
nir_ssa_alu_instr_src_components(const nir_alu_instr *instr, unsigned src)
{
   assert(instr->dest.dest.is_ssa);

   if (nir_op_infos[instr->op].input_sizes[src] > 0)
      return nir_op_infos[instr->op].input_sizes[src];

   return instr->dest.dest.ssa.num_components;
}

bool nir_alu_srcs_equal(const nir_alu_instr *alu1, const nir_alu_instr *alu2,
                        unsigned src1, unsigned src2);

typedef enum {
   nir_deref_type_var,
   nir_deref_type_array,
   nir_deref_type_struct
} nir_deref_type;

typedef struct nir_deref {
   nir_deref_type deref_type;
   struct nir_deref *child;
   const struct glsl_type *type;
} nir_deref;

typedef struct {
   nir_deref deref;

   nir_variable *var;
} nir_deref_var;

/* This enum describes how the array is referenced.  If the deref is
 * direct then the base_offset is used.  If the deref is indirect then
 * offset is given by base_offset + indirect.  If the deref is a wildcard
 * then the deref refers to all of the elements of the array at the same
 * time.  Wildcard dereferences are only ever allowed in copy_var
 * intrinsics and the source and destination derefs must have matching
 * wildcards.
 */
typedef enum {
   nir_deref_array_type_direct,
   nir_deref_array_type_indirect,
   nir_deref_array_type_wildcard,
} nir_deref_array_type;

typedef struct {
   nir_deref deref;

   nir_deref_array_type deref_array_type;
   unsigned base_offset;
   nir_src indirect;
} nir_deref_array;

typedef struct {
   nir_deref deref;

   unsigned index;
} nir_deref_struct;

NIR_DEFINE_CAST(nir_deref_as_var, nir_deref, nir_deref_var, deref,
                deref_type, nir_deref_type_var)
NIR_DEFINE_CAST(nir_deref_as_array, nir_deref, nir_deref_array, deref,
                deref_type, nir_deref_type_array)
NIR_DEFINE_CAST(nir_deref_as_struct, nir_deref, nir_deref_struct, deref,
                deref_type, nir_deref_type_struct)

/* Returns the last deref in the chain. */
static inline nir_deref *
nir_deref_tail(nir_deref *deref)
{
   while (deref->child)
      deref = deref->child;
   return deref;
}

typedef struct {
   nir_instr instr;

   unsigned num_params;
   nir_deref_var **params;
   nir_deref_var *return_deref;

   struct nir_function *callee;
} nir_call_instr;

#define INTRINSIC(name, num_srcs, src_components, has_dest, dest_components, \
                  num_variables, num_indices, idx0, idx1, idx2, flags) \
   nir_intrinsic_##name,

#define LAST_INTRINSIC(name) nir_last_intrinsic = nir_intrinsic_##name,

typedef enum {
#include "nir_intrinsics.h"
   nir_num_intrinsics = nir_last_intrinsic + 1
} nir_intrinsic_op;

#define NIR_INTRINSIC_MAX_CONST_INDEX 3

/** Represents an intrinsic
 *
 * An intrinsic is an instruction type for handling things that are
 * more-or-less regular operations but don't just consume and produce SSA
 * values like ALU operations do.  Intrinsics are not for things that have
 * special semantic meaning such as phi nodes and parallel copies.
 * Examples of intrinsics include variable load/store operations, system
 * value loads, and the like.  Even though texturing more-or-less falls
 * under this category, texturing is its own instruction type because
 * trying to represent texturing with intrinsics would lead to a
 * combinatorial explosion of intrinsic opcodes.
 *
 * By having a single instruction type for handling a lot of different
 * cases, optimization passes can look for intrinsics and, for the most
 * part, completely ignore them.  Each intrinsic type also has a few
 * possible flags that govern whether or not they can be reordered or
 * eliminated.  That way passes like dead code elimination can still work
 * on intrisics without understanding the meaning of each.
 *
 * Each intrinsic has some number of constant indices, some number of
 * variables, and some number of sources.  What these sources, variables,
 * and indices mean depends on the intrinsic and is documented with the
 * intrinsic declaration in nir_intrinsics.h.  Intrinsics and texture
 * instructions are the only types of instruction that can operate on
 * variables.
 */
typedef struct {
   nir_instr instr;

   nir_intrinsic_op intrinsic;

   nir_dest dest;

   /** number of components if this is a vectorized intrinsic
    *
    * Similarly to ALU operations, some intrinsics are vectorized.
    * An intrinsic is vectorized if nir_intrinsic_infos.dest_components == 0.
    * For vectorized intrinsics, the num_components field specifies the
    * number of destination components and the number of source components
    * for all sources with nir_intrinsic_infos.src_components[i] == 0.
    */
   uint8_t num_components;

   int const_index[NIR_INTRINSIC_MAX_CONST_INDEX];

   nir_deref_var *variables[2];

   nir_src src[];
} nir_intrinsic_instr;

/**
 * \name NIR intrinsics semantic flags
 *
 * information about what the compiler can do with the intrinsics.
 *
 * \sa nir_intrinsic_info::flags
 */
typedef enum {
   /**
    * whether the intrinsic can be safely eliminated if none of its output
    * value is not being used.
    */
   NIR_INTRINSIC_CAN_ELIMINATE = (1 << 0),

   /**
    * Whether the intrinsic can be reordered with respect to any other
    * intrinsic, i.e. whether the only reordering dependencies of the
    * intrinsic are due to the register reads/writes.
    */
   NIR_INTRINSIC_CAN_REORDER = (1 << 1),
} nir_intrinsic_semantic_flag;

/**
 * \name NIR intrinsics const-index flag
 *
 * Indicates the usage of a const_index slot.
 *
 * \sa nir_intrinsic_info::index_map
 */
typedef enum {
   /**
    * Generally instructions that take a offset src argument, can encode
    * a constant 'base' value which is added to the offset.
    */
   NIR_INTRINSIC_BASE = 1,

   /**
    * For store instructions, a writemask for the store.
    */
   NIR_INTRINSIC_WRMASK = 2,

   /**
    * The stream-id for GS emit_vertex/end_primitive intrinsics.
    */
   NIR_INTRINSIC_STREAM_ID = 3,

   /**
    * The clip-plane id for load_user_clip_plane intrinsic.
    */
   NIR_INTRINSIC_UCP_ID = 4,

   /**
    * The amount of data, starting from BASE, that this instruction may
    * access.  This is used to provide bounds if the offset is not constant.
    */
   NIR_INTRINSIC_RANGE = 5,

   /**
    * The Vulkan descriptor set for vulkan_resource_index intrinsic.
    */
   NIR_INTRINSIC_DESC_SET = 6,

   /**
    * The Vulkan descriptor set binding for vulkan_resource_index intrinsic.
    */
   NIR_INTRINSIC_BINDING = 7,

   /**
    * Component offset.
    */
   NIR_INTRINSIC_COMPONENT = 8,

   /**
    * Interpolation mode (only meaningful for FS inputs).
    */
   NIR_INTRINSIC_INTERP_MODE = 9,

   NIR_INTRINSIC_NUM_INDEX_FLAGS,

} nir_intrinsic_index_flag;

#define NIR_INTRINSIC_MAX_INPUTS 4

typedef struct {
   const char *name;

   unsigned num_srcs; /** < number of register/SSA inputs */

   /** number of components of each input register
    *
    * If this value is 0, the number of components is given by the
    * num_components field of nir_intrinsic_instr.
    */
   unsigned src_components[NIR_INTRINSIC_MAX_INPUTS];

   bool has_dest;

   /** number of components of the output register
    *
    * If this value is 0, the number of components is given by the
    * num_components field of nir_intrinsic_instr.
    */
   unsigned dest_components;

   /** the number of inputs/outputs that are variables */
   unsigned num_variables;

   /** the number of constant indices used by the intrinsic */
   unsigned num_indices;

   /** indicates the usage of intr->const_index[n] */
   unsigned index_map[NIR_INTRINSIC_NUM_INDEX_FLAGS];

   /** semantic flags for calls to this intrinsic */
   nir_intrinsic_semantic_flag flags;
} nir_intrinsic_info;

extern const nir_intrinsic_info nir_intrinsic_infos[nir_num_intrinsics];


#define INTRINSIC_IDX_ACCESSORS(name, flag, type)                             \
static inline type                                                            \
nir_intrinsic_##name(nir_intrinsic_instr *instr)                              \
{                                                                             \
   const nir_intrinsic_info *info = &nir_intrinsic_infos[instr->intrinsic];   \
   assert(info->index_map[NIR_INTRINSIC_##flag] > 0);                         \
   return instr->const_index[info->index_map[NIR_INTRINSIC_##flag] - 1];      \
}                                                                             \
static inline void                                                            \
nir_intrinsic_set_##name(nir_intrinsic_instr *instr, type val)                \
{                                                                             \
   const nir_intrinsic_info *info = &nir_intrinsic_infos[instr->intrinsic];   \
   assert(info->index_map[NIR_INTRINSIC_##flag] > 0);                         \
   instr->const_index[info->index_map[NIR_INTRINSIC_##flag] - 1] = val;       \
}

INTRINSIC_IDX_ACCESSORS(write_mask, WRMASK, unsigned)
INTRINSIC_IDX_ACCESSORS(base, BASE, int)
INTRINSIC_IDX_ACCESSORS(stream_id, STREAM_ID, unsigned)
INTRINSIC_IDX_ACCESSORS(ucp_id, UCP_ID, unsigned)
INTRINSIC_IDX_ACCESSORS(range, RANGE, unsigned)
INTRINSIC_IDX_ACCESSORS(desc_set, DESC_SET, unsigned)
INTRINSIC_IDX_ACCESSORS(binding, BINDING, unsigned)
INTRINSIC_IDX_ACCESSORS(component, COMPONENT, unsigned)
INTRINSIC_IDX_ACCESSORS(interp_mode, INTERP_MODE, unsigned)

/**
 * \group texture information
 *
 * This gives semantic information about textures which is useful to the
 * frontend, the backend, and lowering passes, but not the optimizer.
 */

typedef enum {
   nir_tex_src_coord,
   nir_tex_src_projector,
   nir_tex_src_comparator, /* shadow comparator */
   nir_tex_src_offset,
   nir_tex_src_bias,
   nir_tex_src_lod,
   nir_tex_src_ms_index, /* MSAA sample index */
   nir_tex_src_ms_mcs, /* MSAA compression value */
   nir_tex_src_ddx,
   nir_tex_src_ddy,
   nir_tex_src_texture_offset, /* < dynamically uniform indirect offset */
   nir_tex_src_sampler_offset, /* < dynamically uniform indirect offset */
   nir_tex_src_plane,          /* < selects plane for planar textures */
   nir_num_tex_src_types
} nir_tex_src_type;

typedef struct {
   nir_src src;
   nir_tex_src_type src_type;
} nir_tex_src;

typedef enum {
   nir_texop_tex,                /**< Regular texture look-up */
   nir_texop_txb,                /**< Texture look-up with LOD bias */
   nir_texop_txl,                /**< Texture look-up with explicit LOD */
   nir_texop_txd,                /**< Texture look-up with partial derivatvies */
   nir_texop_txf,                /**< Texel fetch with explicit LOD */
   nir_texop_txf_ms,                /**< Multisample texture fetch */
   nir_texop_txf_ms_mcs,         /**< Multisample compression value fetch */
   nir_texop_txs,                /**< Texture size */
   nir_texop_lod,                /**< Texture lod query */
   nir_texop_tg4,                /**< Texture gather */
   nir_texop_query_levels,       /**< Texture levels query */
   nir_texop_texture_samples,    /**< Texture samples query */
   nir_texop_samples_identical,  /**< Query whether all samples are definitely
                                  * identical.
                                  */
} nir_texop;

typedef struct {
   nir_instr instr;

   enum glsl_sampler_dim sampler_dim;
   nir_alu_type dest_type;

   nir_texop op;
   nir_dest dest;
   nir_tex_src *src;
   unsigned num_srcs, coord_components;
   bool is_array, is_shadow;

   /**
    * If is_shadow is true, whether this is the old-style shadow that outputs 4
    * components or the new-style shadow that outputs 1 component.
    */
   bool is_new_style_shadow;

   /* gather component selector */
   unsigned component : 2;

   /** The texture index
    *
    * If this texture instruction has a nir_tex_src_texture_offset source,
    * then the texture index is given by texture_index + texture_offset.
    */
   unsigned texture_index;

   /** The size of the texture array or 0 if it's not an array */
   unsigned texture_array_size;

   /** The texture deref
    *
    * If this is null, use texture_index instead.
    */
   nir_deref_var *texture;

   /** The sampler index
    *
    * The following operations do not require a sampler and, as such, this
    * field should be ignored:
    *    - nir_texop_txf
    *    - nir_texop_txf_ms
    *    - nir_texop_txs
    *    - nir_texop_lod
    *    - nir_texop_tg4
    *    - nir_texop_query_levels
    *    - nir_texop_texture_samples
    *    - nir_texop_samples_identical
    *
    * If this texture instruction has a nir_tex_src_sampler_offset source,
    * then the sampler index is given by sampler_index + sampler_offset.
    */
   unsigned sampler_index;

   /** The sampler deref
    *
    * If this is null, use sampler_index instead.
    */
   nir_deref_var *sampler;
} nir_tex_instr;

static inline unsigned
nir_tex_instr_dest_size(nir_tex_instr *instr)
{
   switch (instr->op) {
   case nir_texop_txs: {
      unsigned ret;
      switch (instr->sampler_dim) {
         case GLSL_SAMPLER_DIM_1D:
         case GLSL_SAMPLER_DIM_BUF:
            ret = 1;
            break;
         case GLSL_SAMPLER_DIM_2D:
         case GLSL_SAMPLER_DIM_CUBE:
         case GLSL_SAMPLER_DIM_MS:
         case GLSL_SAMPLER_DIM_RECT:
         case GLSL_SAMPLER_DIM_EXTERNAL:
         case GLSL_SAMPLER_DIM_SUBPASS:
            ret = 2;
            break;
         case GLSL_SAMPLER_DIM_3D:
            ret = 3;
            break;
         default:
            unreachable("not reached");
      }
      if (instr->is_array)
         ret++;
      return ret;
   }

   case nir_texop_lod:
      return 2;

   case nir_texop_texture_samples:
   case nir_texop_query_levels:
   case nir_texop_samples_identical:
      return 1;

   default:
      if (instr->is_shadow && instr->is_new_style_shadow)
         return 1;

      return 4;
   }
}

/* Returns true if this texture operation queries something about the texture
 * rather than actually sampling it.
 */
static inline bool
nir_tex_instr_is_query(nir_tex_instr *instr)
{
   switch (instr->op) {
   case nir_texop_txs:
   case nir_texop_lod:
   case nir_texop_texture_samples:
   case nir_texop_query_levels:
   case nir_texop_txf_ms_mcs:
      return true;
   case nir_texop_tex:
   case nir_texop_txb:
   case nir_texop_txl:
   case nir_texop_txd:
   case nir_texop_txf:
   case nir_texop_txf_ms:
   case nir_texop_tg4:
      return false;
   default:
      unreachable("Invalid texture opcode");
   }
}

static inline nir_alu_type
nir_tex_instr_src_type(nir_tex_instr *instr, unsigned src)
{
   switch (instr->src[src].src_type) {
   case nir_tex_src_coord:
      switch (instr->op) {
      case nir_texop_txf:
      case nir_texop_txf_ms:
      case nir_texop_txf_ms_mcs:
      case nir_texop_samples_identical:
         return nir_type_int;

      default:
         return nir_type_float;
      }

   case nir_tex_src_lod:
      switch (instr->op) {
      case nir_texop_txs:
      case nir_texop_txf:
         return nir_type_int;

      default:
         return nir_type_float;
      }

   case nir_tex_src_projector:
   case nir_tex_src_comparator:
   case nir_tex_src_bias:
   case nir_tex_src_ddx:
   case nir_tex_src_ddy:
      return nir_type_float;

   case nir_tex_src_offset:
   case nir_tex_src_ms_index:
   case nir_tex_src_texture_offset:
   case nir_tex_src_sampler_offset:
      return nir_type_int;

   default:
      unreachable("Invalid texture source type");
   }
}

static inline unsigned
nir_tex_instr_src_size(nir_tex_instr *instr, unsigned src)
{
   if (instr->src[src].src_type == nir_tex_src_coord)
      return instr->coord_components;

   /* The MCS value is expected to be a vec4 returned by a txf_ms_mcs */
   if (instr->src[src].src_type == nir_tex_src_ms_mcs)
      return 4;

   if (instr->src[src].src_type == nir_tex_src_offset ||
       instr->src[src].src_type == nir_tex_src_ddx ||
       instr->src[src].src_type == nir_tex_src_ddy) {
      if (instr->is_array)
         return instr->coord_components - 1;
      else
         return instr->coord_components;
   }

   return 1;
}

static inline int
nir_tex_instr_src_index(nir_tex_instr *instr, nir_tex_src_type type)
{
   for (unsigned i = 0; i < instr->num_srcs; i++)
      if (instr->src[i].src_type == type)
         return (int) i;

   return -1;
}

void nir_tex_instr_remove_src(nir_tex_instr *tex, unsigned src_idx);

typedef struct {
   nir_instr instr;

   nir_const_value value;

   nir_ssa_def def;
} nir_load_const_instr;

typedef enum {
   nir_jump_return,
   nir_jump_break,
   nir_jump_continue,
} nir_jump_type;

typedef struct {
   nir_instr instr;
   nir_jump_type type;
} nir_jump_instr;

/* creates a new SSA variable in an undefined state */

typedef struct {
   nir_instr instr;
   nir_ssa_def def;
} nir_ssa_undef_instr;

typedef struct {
   struct exec_node node;

   /* The predecessor block corresponding to this source */
   struct nir_block *pred;

   nir_src src;
} nir_phi_src;

#define nir_foreach_phi_src(phi_src, phi) \
   foreach_list_typed(nir_phi_src, phi_src, node, &(phi)->srcs)
#define nir_foreach_phi_src_safe(phi_src, phi) \
   foreach_list_typed_safe(nir_phi_src, phi_src, node, &(phi)->srcs)

typedef struct {
   nir_instr instr;

   struct exec_list srcs; /** < list of nir_phi_src */

   nir_dest dest;
} nir_phi_instr;

typedef struct {
   struct exec_node node;
   nir_src src;
   nir_dest dest;
} nir_parallel_copy_entry;

#define nir_foreach_parallel_copy_entry(entry, pcopy) \
   foreach_list_typed(nir_parallel_copy_entry, entry, node, &(pcopy)->entries)

typedef struct {
   nir_instr instr;

   /* A list of nir_parallel_copy_entry's.  The sources of all of the
    * entries are copied to the corresponding destinations "in parallel".
    * In other words, if we have two entries: a -> b and b -> a, the values
    * get swapped.
    */
   struct exec_list entries;
} nir_parallel_copy_instr;

NIR_DEFINE_CAST(nir_instr_as_alu, nir_instr, nir_alu_instr, instr,
                type, nir_instr_type_alu)
NIR_DEFINE_CAST(nir_instr_as_call, nir_instr, nir_call_instr, instr,
                type, nir_instr_type_call)
NIR_DEFINE_CAST(nir_instr_as_jump, nir_instr, nir_jump_instr, instr,
                type, nir_instr_type_jump)
NIR_DEFINE_CAST(nir_instr_as_tex, nir_instr, nir_tex_instr, instr,
                type, nir_instr_type_tex)
NIR_DEFINE_CAST(nir_instr_as_intrinsic, nir_instr, nir_intrinsic_instr, instr,
                type, nir_instr_type_intrinsic)
NIR_DEFINE_CAST(nir_instr_as_load_const, nir_instr, nir_load_const_instr, instr,
                type, nir_instr_type_load_const)
NIR_DEFINE_CAST(nir_instr_as_ssa_undef, nir_instr, nir_ssa_undef_instr, instr,
                type, nir_instr_type_ssa_undef)
NIR_DEFINE_CAST(nir_instr_as_phi, nir_instr, nir_phi_instr, instr,
                type, nir_instr_type_phi)
NIR_DEFINE_CAST(nir_instr_as_parallel_copy, nir_instr,
                nir_parallel_copy_instr, instr,
                type, nir_instr_type_parallel_copy)

/*
 * Control flow
 *
 * Control flow consists of a tree of control flow nodes, which include
 * if-statements and loops. The leaves of the tree are basic blocks, lists of
 * instructions that always run start-to-finish. Each basic block also keeps
 * track of its successors (blocks which may run immediately after the current
 * block) and predecessors (blocks which could have run immediately before the
 * current block). Each function also has a start block and an end block which
 * all return statements point to (which is always empty). Together, all the
 * blocks with their predecessors and successors make up the control flow
 * graph (CFG) of the function. There are helpers that modify the tree of
 * control flow nodes while modifying the CFG appropriately; these should be
 * used instead of modifying the tree directly.
 */

typedef enum {
   nir_cf_node_block,
   nir_cf_node_if,
   nir_cf_node_loop,
   nir_cf_node_function
} nir_cf_node_type;

typedef struct nir_cf_node {
   struct exec_node node;
   nir_cf_node_type type;
   struct nir_cf_node *parent;
} nir_cf_node;

typedef struct nir_block {
   nir_cf_node cf_node;

   struct exec_list instr_list; /** < list of nir_instr */

   /** generic block index; generated by nir_index_blocks */
   unsigned index;

   /*
    * Each block can only have up to 2 successors, so we put them in a simple
    * array - no need for anything more complicated.
    */
   struct nir_block *successors[2];

   /* Set of nir_block predecessors in the CFG */
   struct set *predecessors;

   /*
    * this node's immediate dominator in the dominance tree - set to NULL for
    * the start block.
    */
   struct nir_block *imm_dom;

   /* This node's children in the dominance tree */
   unsigned num_dom_children;
   struct nir_block **dom_children;

   /* Set of nir_block's on the dominance frontier of this block */
   struct set *dom_frontier;

   /*
    * These two indices have the property that dom_{pre,post}_index for each
    * child of this block in the dominance tree will always be between
    * dom_pre_index and dom_post_index for this block, which makes testing if
    * a given block is dominated by another block an O(1) operation.
    */
   unsigned dom_pre_index, dom_post_index;

   /* live in and out for this block; used for liveness analysis */
   BITSET_WORD *live_in;
   BITSET_WORD *live_out;
} nir_block;

static inline nir_instr *
nir_block_first_instr(nir_block *block)
{
   struct exec_node *head = exec_list_get_head(&block->instr_list);
   return exec_node_data(nir_instr, head, node);
}

static inline nir_instr *
nir_block_last_instr(nir_block *block)
{
   struct exec_node *tail = exec_list_get_tail(&block->instr_list);
   return exec_node_data(nir_instr, tail, node);
}

#define nir_foreach_instr(instr, block) \
   foreach_list_typed(nir_instr, instr, node, &(block)->instr_list)
#define nir_foreach_instr_reverse(instr, block) \
   foreach_list_typed_reverse(nir_instr, instr, node, &(block)->instr_list)
#define nir_foreach_instr_safe(instr, block) \
   foreach_list_typed_safe(nir_instr, instr, node, &(block)->instr_list)
#define nir_foreach_instr_reverse_safe(instr, block) \
   foreach_list_typed_reverse_safe(nir_instr, instr, node, &(block)->instr_list)

typedef struct nir_if {
   nir_cf_node cf_node;
   nir_src condition;

   struct exec_list then_list; /** < list of nir_cf_node */
   struct exec_list else_list; /** < list of nir_cf_node */
} nir_if;

typedef struct {
   nir_if *nif;

   nir_instr *conditional_instr;

   nir_block *break_block;
   nir_block *continue_from_block;

   bool continue_from_then;

   struct list_head loop_terminator_link;
} nir_loop_terminator;

typedef struct {
   /* Number of instructions in the loop */
   unsigned num_instructions;

   /* How many times the loop is run (if known) */
   unsigned trip_count;
   bool is_trip_count_known;

   /* Unroll the loop regardless of its size */
   bool force_unroll;

   nir_loop_terminator *limiting_terminator;

   /* A list of loop_terminators terminating this loop. */
   struct list_head loop_terminator_list;
} nir_loop_info;

typedef struct {
   nir_cf_node cf_node;

   struct exec_list body; /** < list of nir_cf_node */

   nir_loop_info *info;
} nir_loop;

/**
 * Various bits of metadata that can may be created or required by
 * optimization and analysis passes
 */
typedef enum {
   nir_metadata_none = 0x0,
   nir_metadata_block_index = 0x1,
   nir_metadata_dominance = 0x2,
   nir_metadata_live_ssa_defs = 0x4,
   nir_metadata_not_properly_reset = 0x8,
   nir_metadata_loop_analysis = 0x10,
} nir_metadata;

typedef struct {
   nir_cf_node cf_node;

   /** pointer to the function of which this is an implementation */
   struct nir_function *function;

   struct exec_list body; /** < list of nir_cf_node */

   nir_block *end_block;

   /** list for all local variables in the function */
   struct exec_list locals;

   /** array of variables used as parameters */
   unsigned num_params;
   nir_variable **params;

   /** variable used to hold the result of the function */
   nir_variable *return_var;

   /** list of local registers in the function */
   struct exec_list registers;

   /** next available local register index */
   unsigned reg_alloc;

   /** next available SSA value index */
   unsigned ssa_alloc;

   /* total number of basic blocks, only valid when block_index_dirty = false */
   unsigned num_blocks;

   nir_metadata valid_metadata;
} nir_function_impl;

ATTRIBUTE_RETURNS_NONNULL static inline nir_block *
nir_start_block(nir_function_impl *impl)
{
   return (nir_block *) impl->body.head_sentinel.next;
}

ATTRIBUTE_RETURNS_NONNULL static inline nir_block *
nir_impl_last_block(nir_function_impl *impl)
{
   return (nir_block *) impl->body.tail_sentinel.prev;
}

static inline nir_cf_node *
nir_cf_node_next(nir_cf_node *node)
{
   struct exec_node *next = exec_node_get_next(&node->node);
   if (exec_node_is_tail_sentinel(next))
      return NULL;
   else
      return exec_node_data(nir_cf_node, next, node);
}

static inline nir_cf_node *
nir_cf_node_prev(nir_cf_node *node)
{
   struct exec_node *prev = exec_node_get_prev(&node->node);
   if (exec_node_is_head_sentinel(prev))
      return NULL;
   else
      return exec_node_data(nir_cf_node, prev, node);
}

static inline bool
nir_cf_node_is_first(const nir_cf_node *node)
{
   return exec_node_is_head_sentinel(node->node.prev);
}

static inline bool
nir_cf_node_is_last(const nir_cf_node *node)
{
   return exec_node_is_tail_sentinel(node->node.next);
}

NIR_DEFINE_CAST(nir_cf_node_as_block, nir_cf_node, nir_block, cf_node,
                type, nir_cf_node_block)
NIR_DEFINE_CAST(nir_cf_node_as_if, nir_cf_node, nir_if, cf_node,
                type, nir_cf_node_if)
NIR_DEFINE_CAST(nir_cf_node_as_loop, nir_cf_node, nir_loop, cf_node,
                type, nir_cf_node_loop)
NIR_DEFINE_CAST(nir_cf_node_as_function, nir_cf_node,
                nir_function_impl, cf_node, type, nir_cf_node_function)

static inline nir_block *
nir_if_first_then_block(nir_if *if_stmt)
{
   struct exec_node *head = exec_list_get_head(&if_stmt->then_list);
   return nir_cf_node_as_block(exec_node_data(nir_cf_node, head, node));
}

static inline nir_block *
nir_if_last_then_block(nir_if *if_stmt)
{
   struct exec_node *tail = exec_list_get_tail(&if_stmt->then_list);
   return nir_cf_node_as_block(exec_node_data(nir_cf_node, tail, node));
}

static inline nir_block *
nir_if_first_else_block(nir_if *if_stmt)
{
   struct exec_node *head = exec_list_get_head(&if_stmt->else_list);
   return nir_cf_node_as_block(exec_node_data(nir_cf_node, head, node));
}

static inline nir_block *
nir_if_last_else_block(nir_if *if_stmt)
{
   struct exec_node *tail = exec_list_get_tail(&if_stmt->else_list);
   return nir_cf_node_as_block(exec_node_data(nir_cf_node, tail, node));
}

static inline nir_block *
nir_loop_first_block(nir_loop *loop)
{
   struct exec_node *head = exec_list_get_head(&loop->body);
   return nir_cf_node_as_block(exec_node_data(nir_cf_node, head, node));
}

static inline nir_block *
nir_loop_last_block(nir_loop *loop)
{
   struct exec_node *tail = exec_list_get_tail(&loop->body);
   return nir_cf_node_as_block(exec_node_data(nir_cf_node, tail, node));
}

typedef enum {
   nir_parameter_in,
   nir_parameter_out,
   nir_parameter_inout,
} nir_parameter_type;

typedef struct {
   nir_parameter_type param_type;
   const struct glsl_type *type;
} nir_parameter;

typedef struct nir_function {
   struct exec_node node;

   const char *name;
   struct nir_shader *shader;

   unsigned num_params;
   nir_parameter *params;
   const struct glsl_type *return_type;

   /** The implementation of this function.
    *
    * If the function is only declared and not implemented, this is NULL.
    */
   nir_function_impl *impl;
} nir_function;

typedef struct nir_shader_compiler_options {
   bool lower_fdiv;
   bool lower_ffma;
   bool fuse_ffma;
   bool lower_flrp32;
   /** Lowers flrp when it does not support doubles */
   bool lower_flrp64;
   bool lower_fpow;
   bool lower_fsat;
   bool lower_fsqrt;
   bool lower_fmod32;
   bool lower_fmod64;
   bool lower_bitfield_extract;
   bool lower_bitfield_insert;
   bool lower_uadd_carry;
   bool lower_usub_borrow;
   /** lowers fneg and ineg to fsub and isub. */
   bool lower_negate;
   /** lowers fsub and isub to fadd+fneg and iadd+ineg. */
   bool lower_sub;

   /* lower {slt,sge,seq,sne} to {flt,fge,feq,fne} + b2f: */
   bool lower_scmp;

   /** enables rules to lower idiv by power-of-two: */
   bool lower_idiv;

   /* Does the native fdot instruction replicate its result for four
    * components?  If so, then opt_algebraic_late will turn all fdotN
    * instructions into fdot_replicatedN instructions.
    */
   bool fdot_replicates;

   /** lowers ffract to fsub+ffloor: */
   bool lower_ffract;

   bool lower_pack_half_2x16;
   bool lower_pack_unorm_2x16;
   bool lower_pack_snorm_2x16;
   bool lower_pack_unorm_4x8;
   bool lower_pack_snorm_4x8;
   bool lower_unpack_half_2x16;
   bool lower_unpack_unorm_2x16;
   bool lower_unpack_snorm_2x16;
   bool lower_unpack_unorm_4x8;
   bool lower_unpack_snorm_4x8;

   bool lower_extract_byte;
   bool lower_extract_word;

   /**
    * Does the driver support real 32-bit integers?  (Otherwise, integers
    * are simulated by floats.)
    */
   bool native_integers;

   /* Indicates that the driver only has zero-based vertex id */
   bool vertex_id_zero_based;

   bool lower_cs_local_index_from_id;

   /**
    * Should nir_lower_io() create load_interpolated_input intrinsics?
    *
    * If not, it generates regular load_input intrinsics and interpolation
    * information must be inferred from the list of input nir_variables.
    */
   bool use_interpolated_input_intrinsics;

   unsigned max_unroll_iterations;
} nir_shader_compiler_options;

typedef struct nir_shader {
   /** list of uniforms (nir_variable) */
   struct exec_list uniforms;

   /** list of inputs (nir_variable) */
   struct exec_list inputs;

   /** list of outputs (nir_variable) */
   struct exec_list outputs;

   /** list of shared compute variables (nir_variable) */
   struct exec_list shared;

   /** Set of driver-specific options for the shader.
    *
    * The memory for the options is expected to be kept in a single static
    * copy by the driver.
    */
   const struct nir_shader_compiler_options *options;

   /** Various bits of compile-time information about a given shader */
   struct shader_info *info;

   /** list of global variables in the shader (nir_variable) */
   struct exec_list globals;

   /** list of system value variables in the shader (nir_variable) */
   struct exec_list system_values;

   struct exec_list functions; /** < list of nir_function */

   /** list of global register in the shader */
   struct exec_list registers;

   /** next available global register index */
   unsigned reg_alloc;

   /**
    * the highest index a load_input_*, load_uniform_*, etc. intrinsic can
    * access plus one
    */
   unsigned num_inputs, num_uniforms, num_outputs, num_shared;

   /** The shader stage, such as MESA_SHADER_VERTEX. */
   gl_shader_stage stage;
} nir_shader;

static inline nir_function_impl *
nir_shader_get_entrypoint(nir_shader *shader)
{
   assert(exec_list_length(&shader->functions) == 1);
   struct exec_node *func_node = exec_list_get_head(&shader->functions);
   nir_function *func = exec_node_data(nir_function, func_node, node);
   assert(func->return_type == glsl_void_type());
   assert(func->num_params == 0);
   assert(func->impl);
   return func->impl;
}

#define nir_foreach_function(func, shader) \
   foreach_list_typed(nir_function, func, node, &(shader)->functions)

nir_shader *nir_shader_create(void *mem_ctx,
                              gl_shader_stage stage,
                              const nir_shader_compiler_options *options,
                              shader_info *si);

/** creates a register, including assigning it an index and adding it to the list */
nir_register *nir_global_reg_create(nir_shader *shader);

nir_register *nir_local_reg_create(nir_function_impl *impl);

void nir_reg_remove(nir_register *reg);

/** Adds a variable to the appropreate list in nir_shader */
void nir_shader_add_variable(nir_shader *shader, nir_variable *var);

static inline void
nir_function_impl_add_variable(nir_function_impl *impl, nir_variable *var)
{
   assert(var->data.mode == nir_var_local);
   exec_list_push_tail(&impl->locals, &var->node);
}

/** creates a variable, sets a few defaults, and adds it to the list */
nir_variable *nir_variable_create(nir_shader *shader,
                                  nir_variable_mode mode,
                                  const struct glsl_type *type,
                                  const char *name);
/** creates a local variable and adds it to the list */
nir_variable *nir_local_variable_create(nir_function_impl *impl,
                                        const struct glsl_type *type,
                                        const char *name);

/** creates a function and adds it to the shader's list of functions */
nir_function *nir_function_create(nir_shader *shader, const char *name);

nir_function_impl *nir_function_impl_create(nir_function *func);
/** creates a function_impl that isn't tied to any particular function */
nir_function_impl *nir_function_impl_create_bare(nir_shader *shader);

nir_block *nir_block_create(nir_shader *shader);
nir_if *nir_if_create(nir_shader *shader);
nir_loop *nir_loop_create(nir_shader *shader);

nir_function_impl *nir_cf_node_get_function(nir_cf_node *node);

/** requests that the given pieces of metadata be generated */
void nir_metadata_require(nir_function_impl *impl, nir_metadata required, ...);
/** dirties all but the preserved metadata */
void nir_metadata_preserve(nir_function_impl *impl, nir_metadata preserved);

/** creates an instruction with default swizzle/writemask/etc. with NULL registers */
nir_alu_instr *nir_alu_instr_create(nir_shader *shader, nir_op op);

nir_jump_instr *nir_jump_instr_create(nir_shader *shader, nir_jump_type type);

nir_load_const_instr *nir_load_const_instr_create(nir_shader *shader,
                                                  unsigned num_components,
                                                  unsigned bit_size);

nir_intrinsic_instr *nir_intrinsic_instr_create(nir_shader *shader,
                                                nir_intrinsic_op op);

nir_call_instr *nir_call_instr_create(nir_shader *shader,
                                      nir_function *callee);

nir_tex_instr *nir_tex_instr_create(nir_shader *shader, unsigned num_srcs);

nir_phi_instr *nir_phi_instr_create(nir_shader *shader);

nir_parallel_copy_instr *nir_parallel_copy_instr_create(nir_shader *shader);

nir_ssa_undef_instr *nir_ssa_undef_instr_create(nir_shader *shader,
                                                unsigned num_components,
                                                unsigned bit_size);

nir_deref_var *nir_deref_var_create(void *mem_ctx, nir_variable *var);
nir_deref_array *nir_deref_array_create(void *mem_ctx);
nir_deref_struct *nir_deref_struct_create(void *mem_ctx, unsigned field_index);

nir_deref *nir_copy_deref(void *mem_ctx, nir_deref *deref);

typedef bool (*nir_deref_foreach_leaf_cb)(nir_deref_var *deref, void *state);
bool nir_deref_foreach_leaf(nir_deref_var *deref,
                            nir_deref_foreach_leaf_cb cb, void *state);

nir_load_const_instr *
nir_deref_get_const_initializer_load(nir_shader *shader, nir_deref_var *deref);

/**
 * NIR Cursors and Instruction Insertion API
 * @{
 *
 * A tiny struct representing a point to insert/extract instructions or
 * control flow nodes.  Helps reduce the combinatorial explosion of possible
 * points to insert/extract.
 *
 * \sa nir_control_flow.h
 */
typedef enum {
   nir_cursor_before_block,
   nir_cursor_after_block,
   nir_cursor_before_instr,
   nir_cursor_after_instr,
} nir_cursor_option;

typedef struct {
   nir_cursor_option option;
   union {
      nir_block *block;
      nir_instr *instr;
   };
} nir_cursor;

static inline nir_block *
nir_cursor_current_block(nir_cursor cursor)
{
   if (cursor.option == nir_cursor_before_instr ||
       cursor.option == nir_cursor_after_instr) {
      return cursor.instr->block;
   } else {
      return cursor.block;
   }
}

bool nir_cursors_equal(nir_cursor a, nir_cursor b);

static inline nir_cursor
nir_before_block(nir_block *block)
{
   nir_cursor cursor;
   cursor.option = nir_cursor_before_block;
   cursor.block = block;
   return cursor;
}

static inline nir_cursor
nir_after_block(nir_block *block)
{
   nir_cursor cursor;
   cursor.option = nir_cursor_after_block;
   cursor.block = block;
   return cursor;
}

static inline nir_cursor
nir_before_instr(nir_instr *instr)
{
   nir_cursor cursor;
   cursor.option = nir_cursor_before_instr;
   cursor.instr = instr;
   return cursor;
}

static inline nir_cursor
nir_after_instr(nir_instr *instr)
{
   nir_cursor cursor;
   cursor.option = nir_cursor_after_instr;
   cursor.instr = instr;
   return cursor;
}

static inline nir_cursor
nir_after_block_before_jump(nir_block *block)
{
   nir_instr *last_instr = nir_block_last_instr(block);
   if (last_instr && last_instr->type == nir_instr_type_jump) {
      return nir_before_instr(last_instr);
   } else {
      return nir_after_block(block);
   }
}

static inline nir_cursor
nir_before_cf_node(nir_cf_node *node)
{
   if (node->type == nir_cf_node_block)
      return nir_before_block(nir_cf_node_as_block(node));

   return nir_after_block(nir_cf_node_as_block(nir_cf_node_prev(node)));
}

static inline nir_cursor
nir_after_cf_node(nir_cf_node *node)
{
   if (node->type == nir_cf_node_block)
      return nir_after_block(nir_cf_node_as_block(node));

   return nir_before_block(nir_cf_node_as_block(nir_cf_node_next(node)));
}

static inline nir_cursor
nir_after_phis(nir_block *block)
{
   nir_foreach_instr(instr, block) {
      if (instr->type != nir_instr_type_phi)
         return nir_before_instr(instr);
   }
   return nir_after_block(block);
}

static inline nir_cursor
nir_after_cf_node_and_phis(nir_cf_node *node)
{
   if (node->type == nir_cf_node_block)
      return nir_after_block(nir_cf_node_as_block(node));

   nir_block *block = nir_cf_node_as_block(nir_cf_node_next(node));

   return nir_after_phis(block);
}

static inline nir_cursor
nir_before_cf_list(struct exec_list *cf_list)
{
   nir_cf_node *first_node = exec_node_data(nir_cf_node,
                                            exec_list_get_head(cf_list), node);
   return nir_before_cf_node(first_node);
}

static inline nir_cursor
nir_after_cf_list(struct exec_list *cf_list)
{
   nir_cf_node *last_node = exec_node_data(nir_cf_node,
                                           exec_list_get_tail(cf_list), node);
   return nir_after_cf_node(last_node);
}

/**
 * Insert a NIR instruction at the given cursor.
 *
 * Note: This does not update the cursor.
 */
void nir_instr_insert(nir_cursor cursor, nir_instr *instr);

static inline void
nir_instr_insert_before(nir_instr *instr, nir_instr *before)
{
   nir_instr_insert(nir_before_instr(instr), before);
}

static inline void
nir_instr_insert_after(nir_instr *instr, nir_instr *after)
{
   nir_instr_insert(nir_after_instr(instr), after);
}

static inline void
nir_instr_insert_before_block(nir_block *block, nir_instr *before)
{
   nir_instr_insert(nir_before_block(block), before);
}

static inline void
nir_instr_insert_after_block(nir_block *block, nir_instr *after)
{
   nir_instr_insert(nir_after_block(block), after);
}

static inline void
nir_instr_insert_before_cf(nir_cf_node *node, nir_instr *before)
{
   nir_instr_insert(nir_before_cf_node(node), before);
}

static inline void
nir_instr_insert_after_cf(nir_cf_node *node, nir_instr *after)
{
   nir_instr_insert(nir_after_cf_node(node), after);
}

static inline void
nir_instr_insert_before_cf_list(struct exec_list *list, nir_instr *before)
{
   nir_instr_insert(nir_before_cf_list(list), before);
}

static inline void
nir_instr_insert_after_cf_list(struct exec_list *list, nir_instr *after)
{
   nir_instr_insert(nir_after_cf_list(list), after);
}

void nir_instr_remove(nir_instr *instr);

/** @} */

typedef bool (*nir_foreach_ssa_def_cb)(nir_ssa_def *def, void *state);
typedef bool (*nir_foreach_dest_cb)(nir_dest *dest, void *state);
typedef bool (*nir_foreach_src_cb)(nir_src *src, void *state);
bool nir_foreach_ssa_def(nir_instr *instr, nir_foreach_ssa_def_cb cb,
                         void *state);
bool nir_foreach_dest(nir_instr *instr, nir_foreach_dest_cb cb, void *state);
bool nir_foreach_src(nir_instr *instr, nir_foreach_src_cb cb, void *state);

nir_const_value *nir_src_as_const_value(nir_src src);
bool nir_src_is_dynamically_uniform(nir_src src);
bool nir_srcs_equal(nir_src src1, nir_src src2);
void nir_instr_rewrite_src(nir_instr *instr, nir_src *src, nir_src new_src);
void nir_instr_move_src(nir_instr *dest_instr, nir_src *dest, nir_src *src);
void nir_if_rewrite_condition(nir_if *if_stmt, nir_src new_src);
void nir_instr_rewrite_dest(nir_instr *instr, nir_dest *dest,
                            nir_dest new_dest);

void nir_ssa_dest_init(nir_instr *instr, nir_dest *dest,
                       unsigned num_components, unsigned bit_size,
                       const char *name);
void nir_ssa_def_init(nir_instr *instr, nir_ssa_def *def,
                      unsigned num_components, unsigned bit_size,
                      const char *name);
void nir_ssa_def_rewrite_uses(nir_ssa_def *def, nir_src new_src);
void nir_ssa_def_rewrite_uses_after(nir_ssa_def *def, nir_src new_src,
                                    nir_instr *after_me);

uint8_t nir_ssa_def_components_read(nir_ssa_def *def);

/*
 * finds the next basic block in source-code order, returns NULL if there is
 * none
 */

nir_block *nir_block_cf_tree_next(nir_block *block);

/* Performs the opposite of nir_block_cf_tree_next() */

nir_block *nir_block_cf_tree_prev(nir_block *block);

/* Gets the first block in a CF node in source-code order */

nir_block *nir_cf_node_cf_tree_first(nir_cf_node *node);

/* Gets the last block in a CF node in source-code order */

nir_block *nir_cf_node_cf_tree_last(nir_cf_node *node);

/* Gets the next block after a CF node in source-code order */

nir_block *nir_cf_node_cf_tree_next(nir_cf_node *node);

/* Macros for loops that visit blocks in source-code order */

#define nir_foreach_block(block, impl) \
   for (nir_block *block = nir_start_block(impl); block != NULL; \
        block = nir_block_cf_tree_next(block))

#define nir_foreach_block_safe(block, impl) \
   for (nir_block *block = nir_start_block(impl), \
        *next = nir_block_cf_tree_next(block); \
        block != NULL; \
        block = next, next = nir_block_cf_tree_next(block))

#define nir_foreach_block_reverse(block, impl) \
   for (nir_block *block = nir_impl_last_block(impl); block != NULL; \
        block = nir_block_cf_tree_prev(block))

#define nir_foreach_block_reverse_safe(block, impl) \
   for (nir_block *block = nir_impl_last_block(impl), \
        *prev = nir_block_cf_tree_prev(block); \
        block != NULL; \
        block = prev, prev = nir_block_cf_tree_prev(block))

#define nir_foreach_block_in_cf_node(block, node) \
   for (nir_block *block = nir_cf_node_cf_tree_first(node); \
        block != nir_cf_node_cf_tree_next(node); \
        block = nir_block_cf_tree_next(block))

/* If the following CF node is an if, this function returns that if.
 * Otherwise, it returns NULL.
 */
nir_if *nir_block_get_following_if(nir_block *block);

nir_loop *nir_block_get_following_loop(nir_block *block);

void nir_index_local_regs(nir_function_impl *impl);
void nir_index_global_regs(nir_shader *shader);
void nir_index_ssa_defs(nir_function_impl *impl);
unsigned nir_index_instrs(nir_function_impl *impl);

void nir_index_blocks(nir_function_impl *impl);

void nir_print_shader(nir_shader *shader, FILE *fp);
void nir_print_shader_annotated(nir_shader *shader, FILE *fp, struct hash_table *errors);
void nir_print_instr(const nir_instr *instr, FILE *fp);

nir_shader *nir_shader_clone(void *mem_ctx, const nir_shader *s);
nir_function_impl *nir_function_impl_clone(const nir_function_impl *fi);
nir_constant *nir_constant_clone(const nir_constant *c, nir_variable *var);
nir_variable *nir_variable_clone(const nir_variable *c, nir_shader *shader);

#ifdef DEBUG
void nir_validate_shader(nir_shader *shader);
void nir_metadata_set_validation_flag(nir_shader *shader);
void nir_metadata_check_validation_flag(nir_shader *shader);

#include "util/debug.h"
static inline bool
should_clone_nir(void)
{
   static int should_clone = -1;
   if (should_clone < 0)
      should_clone = env_var_as_boolean("NIR_TEST_CLONE", false);

   return should_clone;
}
#else
static inline void nir_validate_shader(nir_shader *shader) { (void) shader; }
static inline void nir_metadata_set_validation_flag(nir_shader *shader) { (void) shader; }
static inline void nir_metadata_check_validation_flag(nir_shader *shader) { (void) shader; }
static inline bool should_clone_nir(void) { return false; }
#endif /* DEBUG */

#define _PASS(nir, do_pass) do {                                     \
   do_pass                                                           \
   nir_validate_shader(nir);                                         \
   if (should_clone_nir()) {                                         \
      nir_shader *clone = nir_shader_clone(ralloc_parent(nir), nir); \
      ralloc_free(nir);                                              \
      nir = clone;                                                   \
   }                                                                 \
} while (0)

#define NIR_PASS(progress, nir, pass, ...) _PASS(nir,                \
   nir_metadata_set_validation_flag(nir);                            \
   if (pass(nir, ##__VA_ARGS__)) {                                   \
      progress = true;                                               \
      nir_metadata_check_validation_flag(nir);                       \
   }                                                                 \
)

#define NIR_PASS_V(nir, pass, ...) _PASS(nir,                        \
   pass(nir, ##__VA_ARGS__);                                         \
)

void nir_calc_dominance_impl(nir_function_impl *impl);
void nir_calc_dominance(nir_shader *shader);

nir_block *nir_dominance_lca(nir_block *b1, nir_block *b2);
bool nir_block_dominates(nir_block *parent, nir_block *child);

void nir_dump_dom_tree_impl(nir_function_impl *impl, FILE *fp);
void nir_dump_dom_tree(nir_shader *shader, FILE *fp);

void nir_dump_dom_frontier_impl(nir_function_impl *impl, FILE *fp);
void nir_dump_dom_frontier(nir_shader *shader, FILE *fp);

void nir_dump_cfg_impl(nir_function_impl *impl, FILE *fp);
void nir_dump_cfg(nir_shader *shader, FILE *fp);

int nir_gs_count_vertices(const nir_shader *shader);

bool nir_split_var_copies(nir_shader *shader);

bool nir_lower_returns_impl(nir_function_impl *impl);
bool nir_lower_returns(nir_shader *shader);

bool nir_inline_functions(nir_shader *shader);

bool nir_propagate_invariant(nir_shader *shader);

void nir_lower_var_copy_instr(nir_intrinsic_instr *copy, void *mem_ctx);
void nir_lower_var_copies(nir_shader *shader);

bool nir_lower_global_vars_to_local(nir_shader *shader);

bool nir_lower_indirect_derefs(nir_shader *shader, nir_variable_mode modes);

bool nir_lower_locals_to_regs(nir_shader *shader);

void nir_lower_io_to_temporaries(nir_shader *shader,
                                 nir_function_impl *entrypoint,
                                 bool outputs, bool inputs);

void nir_shader_gather_info(nir_shader *shader, nir_function_impl *entrypoint);

void nir_assign_var_locations(struct exec_list *var_list, unsigned *size,
                              int (*type_size)(const struct glsl_type *));

typedef enum {
   /* If set, this forces all non-flat fragment shader inputs to be
    * interpolated as if with the "sample" qualifier.  This requires
    * nir_shader_compiler_options::use_interpolated_input_intrinsics.
    */
   nir_lower_io_force_sample_interpolation = (1 << 1),
} nir_lower_io_options;
void nir_lower_io(nir_shader *shader,
                  nir_variable_mode modes,
                  int (*type_size)(const struct glsl_type *),
                  nir_lower_io_options);
nir_src *nir_get_io_offset_src(nir_intrinsic_instr *instr);
nir_src *nir_get_io_vertex_index_src(nir_intrinsic_instr *instr);

bool nir_is_per_vertex_io(nir_variable *var, gl_shader_stage stage);

void nir_lower_io_types(nir_shader *shader);
void nir_lower_vars_to_ssa(nir_shader *shader);

bool nir_remove_dead_variables(nir_shader *shader, nir_variable_mode modes);
bool nir_lower_constant_initializers(nir_shader *shader,
                                     nir_variable_mode modes);

void nir_move_vec_src_uses_to_dest(nir_shader *shader);
bool nir_lower_vec_to_movs(nir_shader *shader);
bool nir_lower_alu_to_scalar(nir_shader *shader);
void nir_lower_load_const_to_scalar(nir_shader *shader);

bool nir_lower_phis_to_scalar(nir_shader *shader);
void nir_lower_io_to_scalar(nir_shader *shader, nir_variable_mode mask);

void nir_lower_samplers(nir_shader *shader,
                        const struct gl_shader_program *shader_program);

bool nir_lower_system_values(nir_shader *shader);

typedef struct nir_lower_tex_options {
   /**
    * bitmask of (1 << GLSL_SAMPLER_DIM_x) to control for which
    * sampler types a texture projector is lowered.
    */
   unsigned lower_txp;

   /**
    * If true, lower away nir_tex_src_offset for all texelfetch instructions.
    */
   bool lower_txf_offset;

   /**
    * If true, lower away nir_tex_src_offset for all rect textures.
    */
   bool lower_rect_offset;

   /**
    * If true, lower rect textures to 2D, using txs to fetch the
    * texture dimensions and dividing the texture coords by the
    * texture dims to normalize.
    */
   bool lower_rect;

   /**
    * If true, convert yuv to rgb.
    */
   unsigned lower_y_uv_external;
   unsigned lower_y_u_v_external;
   unsigned lower_yx_xuxv_external;

   /**
    * To emulate certain texture wrap modes, this can be used
    * to saturate the specified tex coord to [0.0, 1.0].  The
    * bits are according to sampler #, ie. if, for example:
    *
    *   (conf->saturate_s & (1 << n))
    *
    * is true, then the s coord for sampler n is saturated.
    *
    * Note that clamping must happen *after* projector lowering
    * so any projected texture sample instruction with a clamped
    * coordinate gets automatically lowered, regardless of the
    * 'lower_txp' setting.
    */
   unsigned saturate_s;
   unsigned saturate_t;
   unsigned saturate_r;

   /* Bitmask of textures that need swizzling.
    *
    * If (swizzle_result & (1 << texture_index)), then the swizzle in
    * swizzles[texture_index] is applied to the result of the texturing
    * operation.
    */
   unsigned swizzle_result;

   /* A swizzle for each texture.  Values 0-3 represent x, y, z, or w swizzles
    * while 4 and 5 represent 0 and 1 respectively.
    */
   uint8_t swizzles[32][4];

   /**
    * Bitmap of textures that need srgb to linear conversion.  If
    * (lower_srgb & (1 << texture_index)) then the rgb (xyz) components
    * of the texture are lowered to linear.
    */
   unsigned lower_srgb;

   /**
    * If true, lower nir_texop_txd on cube maps with nir_texop_txl.
    */
   bool lower_txd_cube_map;

   /**
    * If true, lower nir_texop_txd on shadow samplers (except cube maps)
    * with nir_texop_txl. Notice that cube map shadow samplers are lowered
    * with lower_txd_cube_map.
    */
   bool lower_txd_shadow;
} nir_lower_tex_options;

bool nir_lower_tex(nir_shader *shader,
                   const nir_lower_tex_options *options);

bool nir_lower_idiv(nir_shader *shader);

void nir_lower_clip_vs(nir_shader *shader, unsigned ucp_enables);
void nir_lower_clip_fs(nir_shader *shader, unsigned ucp_enables);
void nir_lower_clip_cull_distance_arrays(nir_shader *nir);

void nir_lower_two_sided_color(nir_shader *shader);

void nir_lower_clamp_color_outputs(nir_shader *shader);

void nir_lower_passthrough_edgeflags(nir_shader *shader);

typedef struct nir_lower_wpos_ytransform_options {
   int state_tokens[5];
   bool fs_coord_origin_upper_left :1;
   bool fs_coord_origin_lower_left :1;
   bool fs_coord_pixel_center_integer :1;
   bool fs_coord_pixel_center_half_integer :1;
} nir_lower_wpos_ytransform_options;

bool nir_lower_wpos_ytransform(nir_shader *shader,
                               const nir_lower_wpos_ytransform_options *options);
bool nir_lower_wpos_center(nir_shader *shader);

typedef struct nir_lower_drawpixels_options {
   int texcoord_state_tokens[5];
   int scale_state_tokens[5];
   int bias_state_tokens[5];
   unsigned drawpix_sampler;
   unsigned pixelmap_sampler;
   bool pixel_maps :1;
   bool scale_and_bias :1;
} nir_lower_drawpixels_options;

void nir_lower_drawpixels(nir_shader *shader,
                          const nir_lower_drawpixels_options *options);

typedef struct nir_lower_bitmap_options {
   unsigned sampler;
   bool swizzle_xxxx;
} nir_lower_bitmap_options;

void nir_lower_bitmap(nir_shader *shader, const nir_lower_bitmap_options *options);

void nir_lower_atomics(nir_shader *shader,
                       const struct gl_shader_program *shader_program);
void nir_lower_to_source_mods(nir_shader *shader);

bool nir_lower_gs_intrinsics(nir_shader *shader);

typedef enum {
   nir_lower_drcp = (1 << 0),
   nir_lower_dsqrt = (1 << 1),
   nir_lower_drsq = (1 << 2),
   nir_lower_dtrunc = (1 << 3),
   nir_lower_dfloor = (1 << 4),
   nir_lower_dceil = (1 << 5),
   nir_lower_dfract = (1 << 6),
   nir_lower_dround_even = (1 << 7),
   nir_lower_dmod = (1 << 8)
} nir_lower_doubles_options;

void nir_lower_doubles(nir_shader *shader, nir_lower_doubles_options options);
void nir_lower_double_pack(nir_shader *shader);

bool nir_normalize_cubemap_coords(nir_shader *shader);

void nir_live_ssa_defs_impl(nir_function_impl *impl);

void nir_loop_analyze_impl(nir_function_impl *impl,
                           nir_variable_mode indirect_mask);

bool nir_ssa_defs_interfere(nir_ssa_def *a, nir_ssa_def *b);

void nir_convert_to_ssa_impl(nir_function_impl *impl);
void nir_convert_to_ssa(nir_shader *shader);

bool nir_repair_ssa_impl(nir_function_impl *impl);
bool nir_repair_ssa(nir_shader *shader);

/* If phi_webs_only is true, only convert SSA values involved in phi nodes to
 * registers.  If false, convert all values (even those not involved in a phi
 * node) to registers.
 */
void nir_convert_from_ssa(nir_shader *shader, bool phi_webs_only);

bool nir_lower_phis_to_regs_block(nir_block *block);
bool nir_lower_ssa_defs_to_regs_block(nir_block *block);

bool nir_opt_algebraic(nir_shader *shader);
bool nir_opt_algebraic_late(nir_shader *shader);
bool nir_opt_constant_folding(nir_shader *shader);

bool nir_opt_global_to_local(nir_shader *shader);

bool nir_copy_prop(nir_shader *shader);

bool nir_opt_cse(nir_shader *shader);

bool nir_opt_dce(nir_shader *shader);

bool nir_opt_dead_cf(nir_shader *shader);

bool nir_opt_gcm(nir_shader *shader, bool value_number);

bool nir_opt_peephole_select(nir_shader *shader, unsigned limit);

bool nir_opt_remove_phis(nir_shader *shader);

bool nir_opt_undef(nir_shader *shader);

bool nir_opt_conditional_discard(nir_shader *shader);

void nir_sweep(nir_shader *shader);

nir_intrinsic_op nir_intrinsic_from_system_value(gl_system_value val);
gl_system_value nir_system_value_from_intrinsic(nir_intrinsic_op intrin);

#ifdef __cplusplus
} /* extern "C" */
#endif