gpu.h

#ifndef _GPU_H
#define _GPU_H

#include <isl/ast.h>
#include <isl/id.h>
#include <isl/id_to_ast_expr.h>

#include <pet.h>

#include "ppcg.h"
#include "ppcg_options.h"

/* An access to an outer array element or an iterator.
 * Accesses to iterators have an access relation that maps to an unnamed space.
 * An access may be both read and write.
 * If the access relation is empty, then the output dimension may
 * not be equal to the dimension of the corresponding array.
 */
struct gpu_stmt_access {
	/* Access reads elements */
	int read;
	/* Access writes elements */
	int write;
	/* All writes are definite writes. */
	int exact_write;
	/* Is a single, fixed element being accessed? */
	isl_bool fixed_element;
	/* The number of index expressions specified in the access. */
	int n_index;

	/* May access relation */
	isl_map *access;
	/* May access relation with as domain a mapping from iteration domain
	 * to a reference identifier.
	 */
	isl_map *tagged_access;
	/* The reference id of the corresponding pet_expr. */
	isl_id *ref_id;

	struct gpu_stmt_access *next;
};

/* A representation of a user statement.
 * "stmt" points to the corresponding pet statement.
 * "id" is the identifier of the instance set of the statement.
 * "accesses" is a linked list of accesses performed by the statement.
 * If the statement has been killed, i.e., if it will not be scheduled,
 * then this linked list may be empty even if the actual statement does
 * perform accesses.
 */
struct gpu_stmt {
	isl_id *id;
	struct pet_stmt *stmt;

	struct gpu_stmt_access *accesses;
};

/* Represents an outer array possibly accessed by a gpu_prog.
 */
struct gpu_array_info {
	/* The array data space. */
	isl_space *space;
	/* Element type. */
	char *type;
	/* Element size. */
	int size;
	/* Name of the array. */
	char *name;
	/* Declared extent of original array. */
	isl_set *declared_extent;
	/* AST expression for declared size of original array. */
	isl_ast_expr *declared_size;
	/* Extent of the array that needs to be copied. */
	isl_set *extent;
	/* Number of indices. */
	unsigned n_index;
	/* For each index, a bound on "extent" in that direction. */
	isl_multi_pw_aff *bound;
	/* The corresponding access AST expression, if the array needs
	 * to be allocated on the device.
	 */
	isl_ast_expr *bound_expr;

	/* All references to this array; point to elements of a linked list. */
	int n_ref;
	struct gpu_stmt_access **refs;

	/* Is this array accessed at all by the program? */
	int accessed;

	/* Is this a scalar that is read-only within the entire program? */
	int read_only_scalar;

	/* Are the elements of the array structures? */
	int has_compound_element;

	/* Are the elements only accessed through constant index expressions? */
	int only_fixed_element;

	/* Is the array local to the scop? */
	int local;
	/* Is the array local and should it be declared on the host? */
	int declare_local;

	/* Is the corresponding global device memory accessed in any way? */
	int global;

	/* Should the array be linearized? */
	int linearize;

	/* Order dependences on this array.
	 * Only used if live_range_reordering option is set.
	 * It is set to NULL otherwise.
	 */
	isl_union_map *dep_order;
};

/* Represents an outer array accessed by a ppcg_kernel, localized
 * to the context of this kernel.
 *
 * "array" points to the corresponding array in the gpu_prog.
 * The "n_group" "groups" are the reference groups associated to the array.
 * If "force_private" is set, then the array (in practice a scalar)
 * must be mapped to a register.
 * "global" is set if the global device memory corresponding
 * to this array is accessed by the kernel.
 * "bound" is equal to array->bound specialized to the current kernel.
 * "bound_expr" is the corresponding access AST expression.
 */
struct gpu_local_array_info {
	struct gpu_array_info *array;

	int n_group;
	struct gpu_array_ref_group **groups;

	int force_private;
	int global;

	unsigned n_index;
	isl_multi_pw_aff *bound;
	isl_ast_expr *bound_expr;
};

__isl_give isl_ast_expr *gpu_local_array_info_linearize_index(
	struct gpu_local_array_info *array, __isl_take isl_ast_expr *expr);

/* A sequence of "n" names of types.
 */
struct gpu_types {
	int n;
	char **name;
};

/* "read" and "write" contain the original access relations, possibly
 * involving member accesses.
 *
 * The elements of "array", as well as the ranges of "copy_in" and "copy_out"
 * only refer to the outer arrays of any possible member accesses.
 */
struct gpu_prog {
	isl_ctx *ctx;

	struct ppcg_scop *scop;

	/* Set of parameter values */
	isl_set *context;

	/* All potential read accesses in the entire program */
	isl_union_map *read;

	/* All potential write accesses in the entire program */
	isl_union_map *may_write;
	/* All definite write accesses in the entire program */
	isl_union_map *must_write;
	/* All tagged definite kills in the entire program */
	isl_union_map *tagged_must_kill;

	/* The set of inner array elements that may be preserved. */
	isl_union_set *may_persist;

	/* A mapping from all innermost arrays to their outer arrays. */
	isl_union_map *to_outer;
	/* A mapping from the outer arrays to all corresponding inner arrays. */
	isl_union_map *to_inner;
	/* A mapping from all intermediate arrays to their outer arrays,
	 * including an identity mapping from the anonymous 1D space to itself.
	 */
	isl_union_map *any_to_outer;

	/* Order dependences on non-scalars. */
	isl_union_map *array_order;

	/* Array of statements */
	int n_stmts;
	struct gpu_stmt *stmts;

	int n_array;
	struct gpu_array_info *array;
};

struct gpu_gen {
	isl_ctx *ctx;
	struct ppcg_options *options;

	/* Callback for printing of AST in appropriate format. */
	__isl_give isl_printer *(*print)(__isl_take isl_printer *p,
		struct gpu_prog *prog, __isl_keep isl_ast_node *tree,
		struct gpu_types *types, void *user);
	void *print_user;

	struct gpu_prog *prog;
	/* The generated AST. */
	isl_ast_node *tree;

	/* The sequence of types for which a definition has been printed. */
	struct gpu_types types;

	/* User specified tile, grid and block sizes for each kernel */
	isl_union_map *sizes;

	/* Effectively used tile, grid and block sizes for each kernel */
	isl_union_map *used_sizes;

	/* Identifier of the next kernel. */
	int kernel_id;
};

enum ppcg_group_access_type {
	ppcg_access_global,
	ppcg_access_shared,
	ppcg_access_private
};

enum ppcg_kernel_stmt_type {
	ppcg_kernel_copy,
	ppcg_kernel_domain,
	ppcg_kernel_sync
};

/* Representation of special statements, in particular copy statements
 * and __syncthreads statements, inside a kernel.
 *
 * type represents the kind of statement
 *
 *
 * for ppcg_kernel_copy statements we have
 *
 * read is set if the statement should copy data from global memory
 * to shared memory or registers.
 *
 * index expresses an access to the array element that needs to be copied
 * local_index expresses the corresponding element in the tile
 *
 * array refers to the original array being copied
 * local_array is a pointer to the appropriate element in the "array"
 *	array of the ppcg_kernel to which this copy access belongs
 *
 *
 * for ppcg_kernel_domain statements we have
 *
 * stmt is the corresponding input statement
 *
 * n_access is the number of accesses in stmt
 * access is an array of local information about the accesses
 */
struct ppcg_kernel_stmt {
	enum ppcg_kernel_stmt_type type;

	union {
		struct {
			int read;
			isl_ast_expr *index;
			isl_ast_expr *local_index;
			struct gpu_array_info *array;
			struct gpu_local_array_info *local_array;
		} c;
		struct {
			struct gpu_stmt *stmt;
			isl_id_to_ast_expr *ref2expr;
		} d;
	} u;
};

/* Representation of a local variable in a kernel.
 */
struct ppcg_kernel_var {
	struct gpu_array_info *array;
	enum ppcg_group_access_type type;
	char *name;
	isl_vec *size;
};

/* Representation of a kernel.
 *
 * prog describes the original code from which the kernel is extracted.
 *
 * id is the sequence number of the kernel.
 *
 * block_ids contains the list of block identifiers for this kernel.
 * thread_ids contains the list of thread identifiers for this kernel.
 *
 * the first n_grid elements of grid_dim represent the specified size
 * of the grid.
 * the first n_block elements of block_dim represent the specified or
 * effective size of the block.
 * Note that in the input file, the sizes of the grid and the blocks
 * are specified in the order x, y, z, but internally, the sizes
 * are stored in reverse order, so that the last element always
 * refers to the x dimension.
 *
 * grid_size reflects the effective grid size.
 * grid_size_expr contains a corresponding access AST expression, built within
 * the context where the launch appears.
 *
 * context contains the values of the parameters and outer schedule dimensions
 * for which any statement instance in this kernel needs to be executed.
 *
 * n_sync is the number of synchronization operations that have
 * been introduced in the schedule tree corresponding to this kernel (so far).
 *
 * core contains the spaces of the statement domains that form
 * the core computation of the kernel.  It is used to navigate
 * the tree during the construction of the device part of the schedule
 * tree in gpu_create_kernel.
 *
 * expanded_domain contains the original statement instances,
 * i.e., those that appear in the domains of access relations,
 * that are involved in the kernel.
 * contraction maps those original statement instances to
 * the statement instances that are active at the point
 * in the schedule tree where the kernel is created.
 *
 * arrays is the set of possibly accessed outer array elements.
 *
 * space is the schedule space of the AST context.  That is, it represents
 * the loops of the generated host code containing the kernel launch.
 *
 * n_array is the total number of arrays in the input program and also
 * the number of element in the array array.
 * array contains information about each array that is local
 * to the current kernel.  If an array is not used in a kernel,
 * then the corresponding entry does not contain any information.
 *
 * any_force_private is set if any array in the kernel is marked force_private
 *
 * block_filter contains constraints on the domain elements in the kernel
 * that encode the mapping to block identifiers, where the block identifiers
 * are represented by "n_grid" parameters with as names the elements
 * of "block_ids".
 *
 * thread_filter contains constraints on the domain elements in the kernel
 * that encode the mapping to thread identifiers, where the thread identifiers
 * are represented by "n_block" parameters with as names the elements
 * of "thread_ids".
 *
 * copy_schedule corresponds to the schedule dimensions of
 * the (tiled) schedule for this kernel that have been taken into account
 * for computing private/shared memory tiles.
 * The domain corresponds to the original statement instances, i.e.,
 * those that appear in the leaves of the schedule tree.
 * copy_schedule_dim is the dimension of this schedule.
 *
 * sync_writes contains write references that require synchronization.
 * Each reference is represented by a universe set in a space [S[i,j] -> R[]]
 * with S[i,j] the statement instance space and R[] the array reference.
 */
struct ppcg_kernel {
	isl_ctx *ctx;
	struct ppcg_options *options;

	struct gpu_prog *prog;

	int id;

	isl_id_list *block_ids;
	isl_id_list *thread_ids;

	int n_grid;
	int n_block;
	int grid_dim[2];
	int block_dim[3];

	isl_multi_pw_aff *grid_size;
	isl_ast_expr *grid_size_expr;
	isl_set *context;

	int n_sync;
	isl_union_set *core;
	isl_union_set *arrays;

	isl_union_pw_multi_aff *contraction;
	isl_union_set *expanded_domain;

	isl_space *space;

	int n_array;
	struct gpu_local_array_info *array;

	int n_var;
	struct ppcg_kernel_var *var;

	int any_force_private;

	isl_union_set *block_filter;
	isl_union_set *thread_filter;
	isl_union_pw_multi_aff *copy_schedule;
	int copy_schedule_dim;

	isl_union_set *sync_writes;

	isl_ast_node *tree;
};

int gpu_array_is_scalar(struct gpu_array_info *array);
int gpu_array_is_read_only_scalar(struct gpu_array_info *array);
int gpu_array_requires_device_allocation(struct gpu_array_info *array);
__isl_give isl_set *gpu_array_positive_size_guard(struct gpu_array_info *array);
isl_bool gpu_array_can_be_private(struct gpu_array_info *array);

struct gpu_prog *gpu_prog_alloc(isl_ctx *ctx, struct ppcg_scop *scop);
void *gpu_prog_free(struct gpu_prog *prog);

int ppcg_kernel_requires_array_argument(struct ppcg_kernel *kernel, int i);

int generate_gpu(isl_ctx *ctx, const char *input, FILE *out,
	struct ppcg_options *options,
	__isl_give isl_printer *(*print)(__isl_take isl_printer *p,
		struct gpu_prog *prog, __isl_keep isl_ast_node *tree,
		struct gpu_types *types, void *user), void *user);

__isl_give isl_schedule_node *gpu_create_kernel(struct gpu_gen *gen,
	__isl_take isl_schedule_node *node, int scale,
	__isl_keep isl_multi_val *sizes);

#endif