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kmp_collapse.h
/*
* kmp_collapse.h -- header for loop collapse feature
*/
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef KMP_COLLAPSE_H
#define KMP_COLLAPSE_H
#include <type_traits>
// Type of the index into the loop nest structures
// (with values from 0 to less than n from collapse(n))
typedef kmp_int32 kmp_index_t;
// Type for combined loop nest space IV:
typedef kmp_uint64 kmp_loop_nest_iv_t;
// Loop has <, <=, etc. as a comparison:
enum comparison_t : kmp_int32 {
comp_less_or_eq = 0,
comp_greater_or_eq = 1,
comp_not_eq = 2,
comp_less = 3,
comp_greater = 4
};
// Type of loop IV.
// Type of bounds and step, after usual promotions
// are a subset of these types (32 & 64 only):
enum loop_type_t : kmp_int32 {
loop_type_uint8 = 0,
loop_type_int8 = 1,
loop_type_uint16 = 2,
loop_type_int16 = 3,
loop_type_uint32 = 4,
loop_type_int32 = 5,
loop_type_uint64 = 6,
loop_type_int64 = 7
};
template <typename T> struct bounds_infoXX_template {
// typedef typename traits_t<T>::unsigned_t UT;
typedef typename traits_t<T>::signed_t ST;
loop_type_t loop_type; // The differentiator
loop_type_t loop_iv_type;
comparison_t comparison;
// outer_iv should be 0 (or any other less then number of dimentions)
// if loop doesn't depend on it (lb1 and ub1 will be 0).
// This way we can do multiplication without a check.
kmp_index_t outer_iv;
// unions to keep the size constant:
union {
T lb0;
kmp_uint64 lb0_u64; // real type can be signed
};
union {
T lb1;
kmp_uint64 lb1_u64; // real type can be signed
};
union {
T ub0;
kmp_uint64 ub0_u64; // real type can be signed
};
union {
T ub1;
kmp_uint64 ub1_u64; // real type can be signed
};
union {
ST step; // signed even if bounds type is unsigned
kmp_int64 step_64; // signed
};
kmp_loop_nest_iv_t trip_count;
};
struct bounds_info_t {
loop_type_t loop_type; // The differentiator
loop_type_t loop_iv_type;
comparison_t comparison;
// outer_iv should be 0 (or any other less then number of dimentions)
// if loop doesn't depend on it (lb1 and ub1 will be 0).
// This way we can do multiplication without a check.
kmp_index_t outer_iv;
kmp_uint64 lb0_u64; // real type can be signed
kmp_uint64 lb1_u64; // real type can be signed
kmp_uint64 ub0_u64; // real type can be signed
kmp_uint64 ub1_u64; // real type can be signed
kmp_int64 step_64; // signed
// This is internal, but it's the only internal thing we need
// in rectangular case, so let's expose it here:
kmp_loop_nest_iv_t trip_count;
};
//-------------------------------------------------------------------------
// Additional types for internal representation:
// Array for a point in the loop space, in the original space.
// It's represented in kmp_uint64, but each dimention is calculated in
// that loop IV type. Also dimentions have to be converted to those types
// when used in generated code.
typedef kmp_uint64* kmp_point_t;
// Array: Number of loop iterations on each nesting level to achieve some point,
// in expanded space or in original space.
// OMPTODO: move from using iterations to using offsets (iterations multiplied
// by steps). For those we need to be careful with the types, as step can be
// negative, but it'll remove multiplications and divisions in several places.
typedef kmp_loop_nest_iv_t* kmp_iterations_t;
// Internal struct with additional info:
template <typename T> struct bounds_info_internalXX_template {
// OMPTODO: should span have type T or should it better be
// kmp_uint64/kmp_int64 depending on T sign? (if kmp_uint64/kmp_int64 than
// updated bounds should probably also be kmp_uint64/kmp_int64). I'd like to
// use big_span_t, if it can be resolved at compile time.
typedef
typename std::conditional<std::is_signed<T>::value, kmp_int64, kmp_uint64>
big_span_t;
// typedef typename big_span_t span_t;
typedef T span_t;
bounds_infoXX_template<T> b; // possibly adjusted bounds
// Leaving this as a union in case we'll switch to span_t with different sizes
// (depending on T)
union {
// Smallest possible value of iv (may be smaller than actually possible)
span_t span_smallest;
kmp_uint64 span_smallest_u64;
};
// Leaving this as a union in case we'll switch to span_t with different sizes
// (depending on T)
union {
// Biggest possible value of iv (may be bigger than actually possible)
span_t span_biggest;
kmp_uint64 span_biggest_u64;
};
// Did we adjust loop bounds (not counting canonicalization)?
bool loop_bounds_adjusted;
};
// Internal struct with additional info:
struct bounds_info_internal_t {
bounds_info_t b; // possibly adjusted bounds
// Smallest possible value of iv (may be smaller than actually possible)
kmp_uint64 span_smallest_u64;
// Biggest possible value of iv (may be bigger than actually possible)
kmp_uint64 span_biggest_u64;
// Did we adjust loop bounds (not counting canonicalization)?
bool loop_bounds_adjusted;
};
//----------APIs for rectangular loop nests--------------------------------
// Canonicalize loop nest and calculate overall trip count.
// "bounds_nest" has to be allocated per thread.
// API will modify original bounds_nest array to bring it to a canonical form
// (only <= and >=, no !=, <, >). If the original loop nest was already in a
// canonical form there will be no changes to bounds in bounds_nest array
// (only trip counts will be calculated).
// Returns trip count of overall space.
extern "C" kmp_loop_nest_iv_t
__kmpc_process_loop_nest_rectang(ident_t *loc, kmp_int32 gtid,
/*in/out*/ bounds_info_t *original_bounds_nest,
kmp_index_t n);
// Calculate old induction variables corresponding to overall new_iv.
// Note: original IV will be returned as if it had kmp_uint64 type,
// will have to be converted to original type in user code.
// Note: trip counts should be already calculated by
// __kmpc_process_loop_nest_rectang.
// OMPTODO: special case 2, 3 nested loops - if it'll be possible to inline
// that into user code.
extern "C" void
__kmpc_calc_original_ivs_rectang(ident_t *loc, kmp_loop_nest_iv_t new_iv,
const bounds_info_t *original_bounds_nest,
/*out*/ kmp_uint64 *original_ivs,
kmp_index_t n);
//----------Init API for non-rectangular loops--------------------------------
// Init API for collapsed loops (static, no chunks defined).
// "bounds_nest" has to be allocated per thread.
// API will modify original bounds_nest array to bring it to a canonical form
// (only <= and >=, no !=, <, >). If the original loop nest was already in a
// canonical form there will be no changes to bounds in bounds_nest array
// (only trip counts will be calculated). Internally API will expand the space
// to parallelogram/parallelepiped, calculate total, calculate bounds for the
// chunks in terms of the new IV, re-calc them in terms of old IVs (especially
// important on the left side, to hit the lower bounds and not step over), and
// pick the correct chunk for this thread (so it will calculate chunks up to the
// needed one). It could be optimized to calculate just this chunk, potentially
// a bit less well distributed among threads. It is designed to make sure that
// threads will receive predictable chunks, deterministically (so that next nest
// of loops with similar characteristics will get exactly same chunks on same
// threads).
// Current contract: chunk_bounds_nest has only lb0 and ub0,
// lb1 and ub1 are set to 0 and can be ignored. (This may change in the future).
extern "C" kmp_int32
__kmpc_for_collapsed_init(ident_t *loc, kmp_int32 gtid,
/*in/out*/ bounds_info_t *original_bounds_nest,
/*out*/ bounds_info_t *chunk_bounds_nest,
kmp_index_t n,
/*out*/ kmp_int32 *plastiter);
#endif // KMP_COLLAPSE_H
bounds_infoXX_template
Definition kmp_collapse.h:52
bounds_info_t
Definition kmp_collapse.h:99
ident
Definition kmp.h:246