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/* Loop autoparallelization.
Copyright (C) 2006-2021 Free Software Foundation, Inc.
Contributed by Sebastian Pop <pop@cri.ensmp.fr>
Zdenek Dvorak <dvorakz@suse.cz> and Razya Ladelsky <razya@il.ibm.com>.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "backend.h"
#include "tree.h"
#include "gimple.h"
#include "cfghooks.h"
#include "tree-pass.h"
#include "ssa.h"
#include "cgraph.h"
#include "gimple-pretty-print.h"
#include "fold-const.h"
#include "gimplify.h"
#include "gimple-iterator.h"
#include "gimplify-me.h"
#include "gimple-walk.h"
#include "stor-layout.h"
#include "tree-nested.h"
#include "tree-cfg.h"
#include "tree-ssa-loop-ivopts.h"
#include "tree-ssa-loop-manip.h"
#include "tree-ssa-loop-niter.h"
#include "tree-ssa-loop.h"
#include "tree-into-ssa.h"
#include "cfgloop.h"
#include "tree-scalar-evolution.h"
#include "langhooks.h"
#include "tree-vectorizer.h"
#include "tree-hasher.h"
#include "tree-parloops.h"
#include "omp-general.h"
#include "omp-low.h"
#include "tree-ssa.h"
#include "tree-ssa-alias.h"
#include "tree-eh.h"
#include "gomp-constants.h"
#include "tree-dfa.h"
#include "stringpool.h"
#include "attribs.h"
/* This pass tries to distribute iterations of loops into several threads.
The implementation is straightforward -- for each loop we test whether its
iterations are independent, and if it is the case (and some additional
conditions regarding profitability and correctness are satisfied), we
add GIMPLE_OMP_PARALLEL and GIMPLE_OMP_FOR codes and let omp expansion
machinery do its job.
The most of the complexity is in bringing the code into shape expected
by the omp expanders:
-- for GIMPLE_OMP_FOR, ensuring that the loop has only one induction
variable and that the exit test is at the start of the loop body
-- for GIMPLE_OMP_PARALLEL, replacing the references to local addressable
variables by accesses through pointers, and breaking up ssa chains
by storing the values incoming to the parallelized loop to a structure
passed to the new function as an argument (something similar is done
in omp gimplification, unfortunately only a small part of the code
can be shared).
TODO:
-- if there are several parallelizable loops in a function, it may be
possible to generate the threads just once (using synchronization to
ensure that cross-loop dependences are obeyed).
-- handling of common reduction patterns for outer loops.
More info can also be found at http://gcc.gnu.org/wiki/AutoParInGCC */
/*
Reduction handling:
currently we use code inspired by vect_force_simple_reduction to detect
reduction patterns.
The code transformation will be introduced by an example.
parloop
{
int sum=1;
for (i = 0; i < N; i++)
{
x[i] = i + 3;
sum+=x[i];
}
}
gimple-like code:
header_bb:
# sum_29 = PHI <sum_11(5), 1(3)>
# i_28 = PHI <i_12(5), 0(3)>
D.1795_8 = i_28 + 3;
x[i_28] = D.1795_8;
sum_11 = D.1795_8 + sum_29;
i_12 = i_28 + 1;
if (N_6(D) > i_12)
goto header_bb;
exit_bb:
# sum_21 = PHI <sum_11(4)>
printf (&"%d"[0], sum_21);
after reduction transformation (only relevant parts):
parloop
{
....
# Storing the initial value given by the user. #
.paral_data_store.32.sum.27 = 1;
#pragma omp parallel num_threads(4)
#pragma omp for schedule(static)
# The neutral element corresponding to the particular
reduction's operation, e.g. 0 for PLUS_EXPR,
1 for MULT_EXPR, etc. replaces the user's initial value. #
# sum.27_29 = PHI <sum.27_11, 0>
sum.27_11 = D.1827_8 + sum.27_29;
GIMPLE_OMP_CONTINUE
# Adding this reduction phi is done at create_phi_for_local_result() #
# sum.27_56 = PHI <sum.27_11, 0>
GIMPLE_OMP_RETURN
# Creating the atomic operation is done at
create_call_for_reduction_1() #
#pragma omp atomic_load
D.1839_59 = *&.paral_data_load.33_51->reduction.23;
D.1840_60 = sum.27_56 + D.1839_59;
#pragma omp atomic_store (D.1840_60);
GIMPLE_OMP_RETURN
# collecting the result after the join of the threads is done at
create_loads_for_reductions().
The value computed by the threads is loaded from the
shared struct. #
.paral_data_load.33_52 = &.paral_data_store.32;
sum_37 = .paral_data_load.33_52->sum.27;
sum_43 = D.1795_41 + sum_37;
exit bb:
# sum_21 = PHI <sum_43, sum_26>
printf (&"%d"[0], sum_21);
...
}
*/
/* Error reporting helper for parloops_is_simple_reduction below. GIMPLE
statement STMT is printed with a message MSG. */
static void
report_ploop_op (dump_flags_t msg_type, gimple *stmt, const char *msg)
{
dump_printf_loc (msg_type, vect_location, "%s%G", msg, stmt);
}
/* DEF_STMT_INFO occurs in a loop that contains a potential reduction
operation. Return true if the results of DEF_STMT_INFO are something
that can be accumulated by such a reduction. */
static bool
parloops_valid_reduction_input_p (stmt_vec_info def_stmt_info)
{
return (is_gimple_assign (def_stmt_info->stmt)
|| is_gimple_call (def_stmt_info->stmt)
|| STMT_VINFO_DEF_TYPE (def_stmt_info) == vect_induction_def
|| (gimple_code (def_stmt_info->stmt) == GIMPLE_PHI
&& STMT_VINFO_DEF_TYPE (def_stmt_info) == vect_internal_def
&& !is_loop_header_bb_p (gimple_bb (def_stmt_info->stmt))));
}
/* Detect SLP reduction of the form:
#a1 = phi <a5, a0>
a2 = operation (a1)
a3 = operation (a2)
a4 = operation (a3)
a5 = operation (a4)
#a = phi <a5>
PHI is the reduction phi node (#a1 = phi <a5, a0> above)
FIRST_STMT is the first reduction stmt in the chain
(a2 = operation (a1)).
Return TRUE if a reduction chain was detected. */
static bool
parloops_is_slp_reduction (loop_vec_info loop_info, gimple *phi,
gimple *first_stmt)
{
class loop *loop = (gimple_bb (phi))->loop_father;
class loop *vect_loop = LOOP_VINFO_LOOP (loop_info);
enum tree_code code;
gimple *loop_use_stmt = NULL;
stmt_vec_info use_stmt_info;
tree lhs;
imm_use_iterator imm_iter;
use_operand_p use_p;
int nloop_uses, size = 0, n_out_of_loop_uses;
bool found = false;
if (loop != vect_loop)
return false;
auto_vec<stmt_vec_info, 8> reduc_chain;
lhs = PHI_RESULT (phi);
code = gimple_assign_rhs_code (first_stmt);
while (1)
{
nloop_uses = 0;
n_out_of_loop_uses = 0;
FOR_EACH_IMM_USE_FAST (use_p, imm_iter, lhs)
{
gimple *use_stmt = USE_STMT (use_p);
if (is_gimple_debug (use_stmt))
continue;
/* Check if we got back to the reduction phi. */
if (use_stmt == phi)
{
loop_use_stmt = use_stmt;
found = true;
break;
}
if (flow_bb_inside_loop_p (loop, gimple_bb (use_stmt)))
{
loop_use_stmt = use_stmt;
nloop_uses++;
}
else
n_out_of_loop_uses++;
/* There are can be either a single use in the loop or two uses in
phi nodes. */
if (nloop_uses > 1 || (n_out_of_loop_uses && nloop_uses))
return false;
}
if (found)
break;
/* We reached a statement with no loop uses. */
if (nloop_uses == 0)
return false;
/* This is a loop exit phi, and we haven't reached the reduction phi. */
if (gimple_code (loop_use_stmt) == GIMPLE_PHI)
return false;
if (!is_gimple_assign (loop_use_stmt)
|| code != gimple_assign_rhs_code (loop_use_stmt)
|| !flow_bb_inside_loop_p (loop, gimple_bb (loop_use_stmt)))
return false;
/* Insert USE_STMT into reduction chain. */
use_stmt_info = loop_info->lookup_stmt (loop_use_stmt);
reduc_chain.safe_push (use_stmt_info);
lhs = gimple_assign_lhs (loop_use_stmt);
size++;
}
if (!found || loop_use_stmt != phi || size < 2)
return false;
/* Swap the operands, if needed, to make the reduction operand be the second
operand. */
lhs = PHI_RESULT (phi);
for (unsigned i = 0; i < reduc_chain.length (); ++i)
{
gassign *next_stmt = as_a <gassign *> (reduc_chain[i]->stmt);
if (gimple_assign_rhs2 (next_stmt) == lhs)
{
tree op = gimple_assign_rhs1 (next_stmt);
stmt_vec_info def_stmt_info = loop_info->lookup_def (op);
/* Check that the other def is either defined in the loop
("vect_internal_def"), or it's an induction (defined by a
loop-header phi-node). */
if (def_stmt_info
&& flow_bb_inside_loop_p (loop, gimple_bb (def_stmt_info->stmt))
&& parloops_valid_reduction_input_p (def_stmt_info))
{
lhs = gimple_assign_lhs (next_stmt);
continue;
}
return false;
}
else
{
tree op = gimple_assign_rhs2 (next_stmt);
stmt_vec_info def_stmt_info = loop_info->lookup_def (op);
/* Check that the other def is either defined in the loop
("vect_internal_def"), or it's an induction (defined by a
loop-header phi-node). */
if (def_stmt_info
&& flow_bb_inside_loop_p (loop, gimple_bb (def_stmt_info->stmt))
&& parloops_valid_reduction_input_p (def_stmt_info))
{
if (dump_enabled_p ())
dump_printf_loc (MSG_NOTE, vect_location, "swapping oprnds: %G",
next_stmt);
swap_ssa_operands (next_stmt,
gimple_assign_rhs1_ptr (next_stmt),
gimple_assign_rhs2_ptr (next_stmt));
update_stmt (next_stmt);
}
else
return false;
}
lhs = gimple_assign_lhs (next_stmt);
}
/* Build up the actual chain. */
for (unsigned i = 0; i < reduc_chain.length () - 1; ++i)
{
REDUC_GROUP_FIRST_ELEMENT (reduc_chain[i]) = reduc_chain[0];
REDUC_GROUP_NEXT_ELEMENT (reduc_chain[i]) = reduc_chain[i+1];
}
REDUC_GROUP_FIRST_ELEMENT (reduc_chain.last ()) = reduc_chain[0];
REDUC_GROUP_NEXT_ELEMENT (reduc_chain.last ()) = NULL;
/* Save the chain for further analysis in SLP detection. */
LOOP_VINFO_REDUCTION_CHAINS (loop_info).safe_push (reduc_chain[0]);
REDUC_GROUP_SIZE (reduc_chain[0]) = size;
return true;
}
/* Return true if we need an in-order reduction for operation CODE
on type TYPE. NEED_WRAPPING_INTEGRAL_OVERFLOW is true if integer
overflow must wrap. */
static bool
parloops_needs_fold_left_reduction_p (tree type, tree_code code,
bool need_wrapping_integral_overflow)
{
/* CHECKME: check for !flag_finite_math_only too? */
if (SCALAR_FLOAT_TYPE_P (type))
switch (code)
{
case MIN_EXPR:
case MAX_EXPR:
return false;
default:
return !flag_associative_math;
}
if (INTEGRAL_TYPE_P (type))
{
if (!operation_no_trapping_overflow (type, code))
return true;
if (need_wrapping_integral_overflow
&& !TYPE_OVERFLOW_WRAPS (type)
&& operation_can_overflow (code))
return true;
return false;
}
if (SAT_FIXED_POINT_TYPE_P (type))
return true;
return false;
}
/* Function parloops_is_simple_reduction
(1) Detect a cross-iteration def-use cycle that represents a simple
reduction computation. We look for the following pattern:
loop_header:
a1 = phi < a0, a2 >
a3 = ...
a2 = operation (a3, a1)
or
a3 = ...
loop_header:
a1 = phi < a0, a2 >
a2 = operation (a3, a1)
such that:
1. operation is commutative and associative and it is safe to
change the order of the computation
2. no uses for a2 in the loop (a2 is used out of the loop)
3. no uses of a1 in the loop besides the reduction operation
4. no uses of a1 outside the loop.
Conditions 1,4 are tested here.
Conditions 2,3 are tested in vect_mark_stmts_to_be_vectorized.
(2) Detect a cross-iteration def-use cycle in nested loops, i.e.,
nested cycles.
(3) Detect cycles of phi nodes in outer-loop vectorization, i.e., double
reductions:
a1 = phi < a0, a2 >
inner loop (def of a3)
a2 = phi < a3 >
(4) Detect condition expressions, ie:
for (int i = 0; i < N; i++)
if (a[i] < val)
ret_val = a[i];
*/
static stmt_vec_info
parloops_is_simple_reduction (loop_vec_info loop_info, stmt_vec_info phi_info,
bool *double_reduc,
bool need_wrapping_integral_overflow,
enum vect_reduction_type *v_reduc_type)
{
gphi *phi = as_a <gphi *> (phi_info->stmt);
class loop *loop = (gimple_bb (phi))->loop_father;
class loop *vect_loop = LOOP_VINFO_LOOP (loop_info);
bool nested_in_vect_loop = flow_loop_nested_p (vect_loop, loop);
gimple *phi_use_stmt = NULL;
enum tree_code orig_code, code;
tree op1, op2, op3 = NULL_TREE, op4 = NULL_TREE;
tree type;
tree name;
imm_use_iterator imm_iter;
use_operand_p use_p;
bool phi_def;
*double_reduc = false;
*v_reduc_type = TREE_CODE_REDUCTION;
tree phi_name = PHI_RESULT (phi);
/* ??? If there are no uses of the PHI result the inner loop reduction
won't be detected as possibly double-reduction by vectorizable_reduction
because that tries to walk the PHI arg from the preheader edge which
can be constant. See PR60382. */
if (has_zero_uses (phi_name))
return NULL;
unsigned nphi_def_loop_uses = 0;
FOR_EACH_IMM_USE_FAST (use_p, imm_iter, phi_name)
{
gimple *use_stmt = USE_STMT (use_p);
if (is_gimple_debug (use_stmt))
continue;
if (!flow_bb_inside_loop_p (loop, gimple_bb (use_stmt)))
{
if (dump_enabled_p ())
dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
"intermediate value used outside loop.\n");
return NULL;
}
nphi_def_loop_uses++;
phi_use_stmt = use_stmt;
}
edge latch_e = loop_latch_edge (loop);
tree loop_arg = PHI_ARG_DEF_FROM_EDGE (phi, latch_e);
if (TREE_CODE (loop_arg) != SSA_NAME)
{
if (dump_enabled_p ())
dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
"reduction: not ssa_name: %T\n", loop_arg);
return NULL;
}
stmt_vec_info def_stmt_info = loop_info->lookup_def (loop_arg);
if (!def_stmt_info
|| !flow_bb_inside_loop_p (loop, gimple_bb (def_stmt_info->stmt)))
return NULL;
if (gassign *def_stmt = dyn_cast <gassign *> (def_stmt_info->stmt))
{
name = gimple_assign_lhs (def_stmt);
phi_def = false;
}
else if (gphi *def_stmt = dyn_cast <gphi *> (def_stmt_info->stmt))
{
name = PHI_RESULT (def_stmt);
phi_def = true;
}
else
{
if (dump_enabled_p ())
dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
"reduction: unhandled reduction operation: %G",
def_stmt_info->stmt);
return NULL;
}
unsigned nlatch_def_loop_uses = 0;
auto_vec<gphi *, 3> lcphis;
bool inner_loop_of_double_reduc = false;
FOR_EACH_IMM_USE_FAST (use_p, imm_iter, name)
{
gimple *use_stmt = USE_STMT (use_p);
if (is_gimple_debug (use_stmt))
continue;
if (flow_bb_inside_loop_p (loop, gimple_bb (use_stmt)))
nlatch_def_loop_uses++;
else
{
/* We can have more than one loop-closed PHI. */
lcphis.safe_push (as_a <gphi *> (use_stmt));
if (nested_in_vect_loop
&& (STMT_VINFO_DEF_TYPE (loop_info->lookup_stmt (use_stmt))
== vect_double_reduction_def))
inner_loop_of_double_reduc = true;
}
}
/* If this isn't a nested cycle or if the nested cycle reduction value
is used ouside of the inner loop we cannot handle uses of the reduction
value. */
if ((!nested_in_vect_loop || inner_loop_of_double_reduc)
&& (nlatch_def_loop_uses > 1 || nphi_def_loop_uses > 1))
{
if (dump_enabled_p ())
dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
"reduction used in loop.\n");
return NULL;
}
/* If DEF_STMT is a phi node itself, we expect it to have a single argument
defined in the inner loop. */
if (phi_def)
{
gphi *def_stmt = as_a <gphi *> (def_stmt_info->stmt);
op1 = PHI_ARG_DEF (def_stmt, 0);
if (gimple_phi_num_args (def_stmt) != 1
|| TREE_CODE (op1) != SSA_NAME)
{
if (dump_enabled_p ())
dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
"unsupported phi node definition.\n");
return NULL;
}
gimple *def1 = SSA_NAME_DEF_STMT (op1);
if (gimple_bb (def1)
&& flow_bb_inside_loop_p (loop, gimple_bb (def_stmt))
&& loop->inner
&& flow_bb_inside_loop_p (loop->inner, gimple_bb (def1))
&& is_gimple_assign (def1)
&& is_a <gphi *> (phi_use_stmt)
&& flow_bb_inside_loop_p (loop->inner, gimple_bb (phi_use_stmt)))
{
if (dump_enabled_p ())
report_ploop_op (MSG_NOTE, def_stmt,
"detected double reduction: ");
*double_reduc = true;
return def_stmt_info;
}
return NULL;
}
/* If we are vectorizing an inner reduction we are executing that
in the original order only in case we are not dealing with a
double reduction. */
bool check_reduction = true;
if (flow_loop_nested_p (vect_loop, loop))
{
gphi *lcphi;
unsigned i;
check_reduction = false;
FOR_EACH_VEC_ELT (lcphis, i, lcphi)
FOR_EACH_IMM_USE_FAST (use_p, imm_iter, gimple_phi_result (lcphi))
{
gimple *use_stmt = USE_STMT (use_p);
if (is_gimple_debug (use_stmt))
continue;
if (! flow_bb_inside_loop_p (vect_loop, gimple_bb (use_stmt)))
check_reduction = true;
}
}
gassign *def_stmt = as_a <gassign *> (def_stmt_info->stmt);
code = orig_code = gimple_assign_rhs_code (def_stmt);
if (nested_in_vect_loop && !check_reduction)
{
/* FIXME: Even for non-reductions code generation is funneled
through vectorizable_reduction for the stmt defining the
PHI latch value. So we have to artificially restrict ourselves
for the supported operations. */
switch (get_gimple_rhs_class (code))
{
case GIMPLE_BINARY_RHS:
case GIMPLE_TERNARY_RHS:
break;
default:
/* Not supported by vectorizable_reduction. */
if (dump_enabled_p ())
report_ploop_op (MSG_MISSED_OPTIMIZATION, def_stmt,
"nested cycle: not handled operation: ");
return NULL;
}
if (dump_enabled_p ())
report_ploop_op (MSG_NOTE, def_stmt, "detected nested cycle: ");
return def_stmt_info;
}
/* We can handle "res -= x[i]", which is non-associative by
simply rewriting this into "res += -x[i]". Avoid changing
gimple instruction for the first simple tests and only do this
if we're allowed to change code at all. */
if (code == MINUS_EXPR && gimple_assign_rhs2 (def_stmt) != phi_name)
code = PLUS_EXPR;
if (code == COND_EXPR)
{
if (! nested_in_vect_loop)
*v_reduc_type = COND_REDUCTION;
op3 = gimple_assign_rhs1 (def_stmt);
if (COMPARISON_CLASS_P (op3))
{
op4 = TREE_OPERAND (op3, 1);
op3 = TREE_OPERAND (op3, 0);
}
if (op3 == phi_name || op4 == phi_name)
{
if (dump_enabled_p ())
report_ploop_op (MSG_MISSED_OPTIMIZATION, def_stmt,
"reduction: condition depends on previous"
" iteration: ");
return NULL;
}
op1 = gimple_assign_rhs2 (def_stmt);
op2 = gimple_assign_rhs3 (def_stmt);
}
else if (!commutative_tree_code (code) || !associative_tree_code (code))
{
if (dump_enabled_p ())
report_ploop_op (MSG_MISSED_OPTIMIZATION, def_stmt,
"reduction: not commutative/associative: ");
return NULL;
}
else if (get_gimple_rhs_class (code) == GIMPLE_BINARY_RHS)
{
op1 = gimple_assign_rhs1 (def_stmt);
op2 = gimple_assign_rhs2 (def_stmt);
}
else
{
if (dump_enabled_p ())
report_ploop_op (MSG_MISSED_OPTIMIZATION, def_stmt,
"reduction: not handled operation: ");
return NULL;
}
if (TREE_CODE (op1) != SSA_NAME && TREE_CODE (op2) != SSA_NAME)
{
if (dump_enabled_p ())
report_ploop_op (MSG_MISSED_OPTIMIZATION, def_stmt,
"reduction: both uses not ssa_names: ");
return NULL;
}
type = TREE_TYPE (gimple_assign_lhs (def_stmt));
if ((TREE_CODE (op1) == SSA_NAME
&& !types_compatible_p (type,TREE_TYPE (op1)))
|| (TREE_CODE (op2) == SSA_NAME
&& !types_compatible_p (type, TREE_TYPE (op2)))
|| (op3 && TREE_CODE (op3) == SSA_NAME
&& !types_compatible_p (type, TREE_TYPE (op3)))
|| (op4 && TREE_CODE (op4) == SSA_NAME
&& !types_compatible_p (type, TREE_TYPE (op4))))
{
if (dump_enabled_p ())
{
dump_printf_loc (MSG_NOTE, vect_location,
"reduction: multiple types: operation type: "
"%T, operands types: %T,%T",
type, TREE_TYPE (op1), TREE_TYPE (op2));
if (op3)
dump_printf (MSG_NOTE, ",%T", TREE_TYPE (op3));
if (op4)
dump_printf (MSG_NOTE, ",%T", TREE_TYPE (op4));
dump_printf (MSG_NOTE, "\n");
}
return NULL;
}
/* Check whether it's ok to change the order of the computation.
Generally, when vectorizing a reduction we change the order of the
computation. This may change the behavior of the program in some
cases, so we need to check that this is ok. One exception is when
vectorizing an outer-loop: the inner-loop is executed sequentially,
and therefore vectorizing reductions in the inner-loop during
outer-loop vectorization is safe. */
if (check_reduction
&& *v_reduc_type == TREE_CODE_REDUCTION
&& parloops_needs_fold_left_reduction_p (type, code,
need_wrapping_integral_overflow))
*v_reduc_type = FOLD_LEFT_REDUCTION;
/* Reduction is safe. We're dealing with one of the following:
1) integer arithmetic and no trapv
2) floating point arithmetic, and special flags permit this optimization
3) nested cycle (i.e., outer loop vectorization). */
stmt_vec_info def1_info = loop_info->lookup_def (op1);
stmt_vec_info def2_info = loop_info->lookup_def (op2);
if (code != COND_EXPR && !def1_info && !def2_info)
{
if (dump_enabled_p ())
report_ploop_op (MSG_NOTE, def_stmt,
"reduction: no defs for operands: ");
return NULL;
}
/* Check that one def is the reduction def, defined by PHI,
the other def is either defined in the loop ("vect_internal_def"),
or it's an induction (defined by a loop-header phi-node). */
if (def2_info
&& def2_info->stmt == phi
&& (code == COND_EXPR
|| !def1_info
|| !flow_bb_inside_loop_p (loop, gimple_bb (def1_info->stmt))
|| parloops_valid_reduction_input_p (def1_info)))
{
if (dump_enabled_p ())
report_ploop_op (MSG_NOTE, def_stmt, "detected reduction: ");
return def_stmt_info;
}
if (def1_info
&& def1_info->stmt == phi
&& (code == COND_EXPR
|| !def2_info
|| !flow_bb_inside_loop_p (loop, gimple_bb (def2_info->stmt))
|| parloops_valid_reduction_input_p (def2_info)))
{
if (! nested_in_vect_loop && orig_code != MINUS_EXPR)
{
/* Check if we can swap operands (just for simplicity - so that
the rest of the code can assume that the reduction variable
is always the last (second) argument). */
if (code == COND_EXPR)
{
/* Swap cond_expr by inverting the condition. */
tree cond_expr = gimple_assign_rhs1 (def_stmt);
enum tree_code invert_code = ERROR_MARK;
enum tree_code cond_code = TREE_CODE (cond_expr);
if (TREE_CODE_CLASS (cond_code) == tcc_comparison)
{
bool honor_nans = HONOR_NANS (TREE_OPERAND (cond_expr, 0));
invert_code = invert_tree_comparison (cond_code, honor_nans);
}
if (invert_code != ERROR_MARK)
{
TREE_SET_CODE (cond_expr, invert_code);
swap_ssa_operands (def_stmt,
gimple_assign_rhs2_ptr (def_stmt),
gimple_assign_rhs3_ptr (def_stmt));
}
else
{
if (dump_enabled_p ())
report_ploop_op (MSG_NOTE, def_stmt,
"detected reduction: cannot swap operands "
"for cond_expr");
return NULL;
}
}
else
swap_ssa_operands (def_stmt, gimple_assign_rhs1_ptr (def_stmt),
gimple_assign_rhs2_ptr (def_stmt));
if (dump_enabled_p ())
report_ploop_op (MSG_NOTE, def_stmt,
"detected reduction: need to swap operands: ");
}
else
{
if (dump_enabled_p ())
report_ploop_op (MSG_NOTE, def_stmt, "detected reduction: ");
}
return def_stmt_info;
}
/* Try to find SLP reduction chain. */
if (! nested_in_vect_loop
&& code != COND_EXPR
&& orig_code != MINUS_EXPR
&& parloops_is_slp_reduction (loop_info, phi, def_stmt))
{
if (dump_enabled_p ())
report_ploop_op (MSG_NOTE, def_stmt,
"reduction: detected reduction chain: ");
return def_stmt_info;
}
/* Look for the expression computing loop_arg from loop PHI result. */
if (check_reduction_path (vect_location, loop, phi, loop_arg, code))
return def_stmt_info;
if (dump_enabled_p ())
{
report_ploop_op (MSG_MISSED_OPTIMIZATION, def_stmt,
"reduction: unknown pattern: ");
}
return NULL;
}
/* Wrapper around vect_is_simple_reduction, which will modify code
in-place if it enables detection of more reductions. Arguments
as there. */
stmt_vec_info
parloops_force_simple_reduction (loop_vec_info loop_info, stmt_vec_info phi_info,
bool *double_reduc,
bool need_wrapping_integral_overflow)
{
enum vect_reduction_type v_reduc_type;
stmt_vec_info def_info
= parloops_is_simple_reduction (loop_info, phi_info, double_reduc,
need_wrapping_integral_overflow,
&v_reduc_type);
if (def_info)
{
STMT_VINFO_REDUC_TYPE (phi_info) = v_reduc_type;
STMT_VINFO_REDUC_DEF (phi_info) = def_info;
STMT_VINFO_REDUC_TYPE (def_info) = v_reduc_type;
STMT_VINFO_REDUC_DEF (def_info) = phi_info;
}
return def_info;
}
/* Minimal number of iterations of a loop that should be executed in each
thread. */
#define MIN_PER_THREAD param_parloops_min_per_thread
/* Element of the hashtable, representing a
reduction in the current loop. */
struct reduction_info
{
gimple *reduc_stmt; /* reduction statement. */
gimple *reduc_phi; /* The phi node defining the reduction. */
enum tree_code reduction_code;/* code for the reduction operation. */
unsigned reduc_version; /* SSA_NAME_VERSION of original reduc_phi
result. */
gphi *keep_res; /* The PHI_RESULT of this phi is the resulting value
of the reduction variable when existing the loop. */
tree initial_value; /* The initial value of the reduction var before entering the loop. */
tree field; /* the name of the field in the parloop data structure intended for reduction. */
tree reduc_addr; /* The address of the reduction variable for
openacc reductions. */
tree init; /* reduction initialization value. */
gphi *new_phi; /* (helper field) Newly created phi node whose result
will be passed to the atomic operation. Represents
the local result each thread computed for the reduction
operation. */
};
/* Reduction info hashtable helpers. */
struct reduction_hasher : free_ptr_hash <reduction_info>
{
static inline hashval_t hash (const reduction_info *);
static inline bool equal (const reduction_info *, const reduction_info *);
};
/* Equality and hash functions for hashtab code. */
inline bool
reduction_hasher::equal (const reduction_info *a, const reduction_info *b)
{
return (a->reduc_phi == b->reduc_phi);
}
inline hashval_t
reduction_hasher::hash (const reduction_info *a)
{
return a->reduc_version;
}
typedef hash_table<reduction_hasher> reduction_info_table_type;
static struct reduction_info *
reduction_phi (reduction_info_table_type *reduction_list, gimple *phi)
{
struct reduction_info tmpred, *red;
if (reduction_list->is_empty () || phi == NULL)
return NULL;
if (gimple_uid (phi) == (unsigned int)-1
|| gimple_uid (phi) == 0)
return NULL;
tmpred.reduc_phi = phi;
tmpred.reduc_version = gimple_uid (phi);
red = reduction_list->find (&tmpred);
gcc_assert (red == NULL || red->reduc_phi == phi);
return red;
}
/* Element of hashtable of names to copy. */
struct name_to_copy_elt
{
unsigned version; /* The version of the name to copy. */
tree new_name; /* The new name used in the copy. */
tree field; /* The field of the structure used to pass the
value. */
};
/* Name copies hashtable helpers. */
struct name_to_copy_hasher : free_ptr_hash <name_to_copy_elt>
{
static inline hashval_t hash (const name_to_copy_elt *);
static inline bool equal (const name_to_copy_elt *, const name_to_copy_elt *);
};
/* Equality and hash functions for hashtab code. */
inline bool
name_to_copy_hasher::equal (const name_to_copy_elt *a, const name_to_copy_elt *b)
{
return a->version == b->version;
}
inline hashval_t
name_to_copy_hasher::hash (const name_to_copy_elt *a)
{
return (hashval_t) a->version;
}
typedef hash_table<name_to_copy_hasher> name_to_copy_table_type;
/* A transformation matrix, which is a self-contained ROWSIZE x COLSIZE
matrix. Rather than use floats, we simply keep a single DENOMINATOR that
represents the denominator for every element in the matrix. */
typedef struct lambda_trans_matrix_s
{
lambda_matrix matrix;
int rowsize;
int colsize;
int denominator;
} *lambda_trans_matrix;
#define LTM_MATRIX(T) ((T)->matrix)
#define LTM_ROWSIZE(T) ((T)->rowsize)
#define LTM_COLSIZE(T) ((T)->colsize)
#define LTM_DENOMINATOR(T) ((T)->denominator)
/* Allocate a new transformation matrix. */
static lambda_trans_matrix
lambda_trans_matrix_new (int colsize, int rowsize,
struct obstack * lambda_obstack)
{
lambda_trans_matrix ret;
ret = (lambda_trans_matrix)
obstack_alloc (lambda_obstack, sizeof (struct lambda_trans_matrix_s));
LTM_MATRIX (ret) = lambda_matrix_new (rowsize, colsize, lambda_obstack);
LTM_ROWSIZE (ret) = rowsize;
LTM_COLSIZE (ret) = colsize;
LTM_DENOMINATOR (ret) = 1;
return ret;
}
/* Multiply a vector VEC by a matrix MAT.
MAT is an M*N matrix, and VEC is a vector with length N. The result
is stored in DEST which must be a vector of length M. */
static void
lambda_matrix_vector_mult (lambda_matrix matrix, int m, int n,
lambda_vector vec, lambda_vector dest)
{
int i, j;
lambda_vector_clear (dest, m);
for (i = 0; i < m; i++)
for (j = 0; j < n; j++)
dest[i] += matrix[i][j] * vec[j];
}
/* Return true if TRANS is a legal transformation matrix that respects
the dependence vectors in DISTS and DIRS. The conservative answer
is false.
"Wolfe proves that a unimodular transformation represented by the
matrix T is legal when applied to a loop nest with a set of
lexicographically non-negative distance vectors RDG if and only if
for each vector d in RDG, (T.d >= 0) is lexicographically positive.
i.e.: if and only if it transforms the lexicographically positive
distance vectors to lexicographically positive vectors. Note that
a unimodular matrix must transform the zero vector (and only it) to
the zero vector." S.Muchnick. */
static bool
lambda_transform_legal_p (lambda_trans_matrix trans,
int nb_loops,
vec<ddr_p> dependence_relations)
{
unsigned int i, j;
lambda_vector distres;
struct data_dependence_relation *ddr;
gcc_assert (LTM_COLSIZE (trans) == nb_loops
&& LTM_ROWSIZE (trans) == nb_loops);
/* When there are no dependences, the transformation is correct. */
if (dependence_relations.length () == 0)
return true;
ddr = dependence_relations[0];
if (ddr == NULL)
return true;
/* When there is an unknown relation in the dependence_relations, we
know that it is no worth looking at this loop nest: give up. */
if (DDR_ARE_DEPENDENT (ddr) == chrec_dont_know)
return false;
distres = lambda_vector_new (nb_loops);
/* For each distance vector in the dependence graph. */
FOR_EACH_VEC_ELT (dependence_relations, i, ddr)
{
/* Don't care about relations for which we know that there is no
dependence, nor about read-read (aka. output-dependences):
these data accesses can happen in any order. */
if (DDR_ARE_DEPENDENT (ddr) == chrec_known
|| (DR_IS_READ (DDR_A (ddr)) && DR_IS_READ (DDR_B (ddr))))
continue;
/* Conservatively answer: "this transformation is not valid". */
if (DDR_ARE_DEPENDENT (ddr) == chrec_dont_know)
return false;
/* If the dependence could not be captured by a distance vector,
conservatively answer that the transform is not valid. */
if (DDR_NUM_DIST_VECTS (ddr) == 0)
return false;
/* Compute trans.dist_vect */
for (j = 0; j < DDR_NUM_DIST_VECTS (ddr); j++)
{
lambda_matrix_vector_mult (LTM_MATRIX (trans), nb_loops, nb_loops,
DDR_DIST_VECT (ddr, j), distres);
if (!lambda_vector_lexico_pos (distres, nb_loops))
return false;
}
}
return true;
}
/* Data dependency analysis. Returns true if the iterations of LOOP
are independent on each other (that is, if we can execute them
in parallel). */
static bool
loop_parallel_p (class loop *loop, struct obstack * parloop_obstack)
{
vec<ddr_p> dependence_relations;
vec<data_reference_p> datarefs;
lambda_trans_matrix trans;
bool ret = false;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "Considering loop %d\n", loop->num);
if (!loop->inner)
fprintf (dump_file, "loop is innermost\n");
else
fprintf (dump_file, "loop NOT innermost\n");
}
/* Check for problems with dependences. If the loop can be reversed,
the iterations are independent. */
auto_vec<loop_p, 3> loop_nest;
datarefs.create (10);
dependence_relations.create (100);
if (! compute_data_dependences_for_loop (loop, true, &loop_nest, &datarefs,
&dependence_relations))
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, " FAILED: cannot analyze data dependencies\n");
ret = false;
goto end;
}
if (dump_file && (dump_flags & TDF_DETAILS))
dump_data_dependence_relations (dump_file, dependence_relations);
trans = lambda_trans_matrix_new (1, 1, parloop_obstack);
LTM_MATRIX (trans)[0][0] = -1;
if (lambda_transform_legal_p (trans, 1, dependence_relations))
{
ret = true;
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, " SUCCESS: may be parallelized\n");
}
else if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file,
" FAILED: data dependencies exist across iterations\n");
end:
free_dependence_relations (dependence_relations);
free_data_refs (datarefs);
return ret;
}
/* Return true when LOOP contains basic blocks marked with the
BB_IRREDUCIBLE_LOOP flag. */
static inline bool
loop_has_blocks_with_irreducible_flag (class loop *loop)
{
unsigned i;
basic_block *bbs = get_loop_body_in_dom_order (loop);
bool res = true;
for (i = 0; i < loop->num_nodes; i++)
if (bbs[i]->flags & BB_IRREDUCIBLE_LOOP)
goto end;
res = false;
end:
free (bbs);
return res;
}
/* Assigns the address of OBJ in TYPE to an ssa name, and returns this name.
The assignment statement is placed on edge ENTRY. DECL_ADDRESS maps decls
to their addresses that can be reused. The address of OBJ is known to
be invariant in the whole function. Other needed statements are placed
right before GSI. */
static tree
take_address_of (tree obj, tree type, edge entry,
int_tree_htab_type *decl_address, gimple_stmt_iterator *gsi)
{
int uid;
tree *var_p, name, addr;
gassign *stmt;
gimple_seq stmts;
/* Since the address of OBJ is invariant, the trees may be shared.
Avoid rewriting unrelated parts of the code. */
obj = unshare_expr (obj);
for (var_p = &obj;
handled_component_p (*var_p);
var_p = &TREE_OPERAND (*var_p, 0))
continue;
/* Canonicalize the access to base on a MEM_REF. */
if (DECL_P (*var_p))
*var_p = build_simple_mem_ref (build_fold_addr_expr (*var_p));
/* Assign a canonical SSA name to the address of the base decl used
in the address and share it for all accesses and addresses based
on it. */
uid = DECL_UID (TREE_OPERAND (TREE_OPERAND (*var_p, 0), 0));
int_tree_map elt;
elt.uid = uid;
int_tree_map *slot = decl_address->find_slot (elt, INSERT);
if (!slot->to)
{
if (gsi == NULL)
return NULL;
addr = TREE_OPERAND (*var_p, 0);
const char *obj_name
= get_name (TREE_OPERAND (TREE_OPERAND (*var_p, 0), 0));
if (obj_name)
name = make_temp_ssa_name (TREE_TYPE (addr), NULL, obj_name);
else
name = make_ssa_name (TREE_TYPE (addr));
stmt = gimple_build_assign (name, addr);
gsi_insert_on_edge_immediate (entry, stmt);
slot->uid = uid;
slot->to = name;
}
else
name = slot->to;
/* Express the address in terms of the canonical SSA name. */
TREE_OPERAND (*var_p, 0) = name;
if (gsi == NULL)
return build_fold_addr_expr_with_type (obj, type);
name = force_gimple_operand (build_addr (obj),
&stmts, true, NULL_TREE);
if (!gimple_seq_empty_p (stmts))
gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
if (!useless_type_conversion_p (type, TREE_TYPE (name)))
{
name = force_gimple_operand (fold_convert (type, name), &stmts, true,
NULL_TREE);
if (!gimple_seq_empty_p (stmts))
gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
}
return name;
}
static tree
reduc_stmt_res (gimple *stmt)
{
return (gimple_code (stmt) == GIMPLE_PHI
? gimple_phi_result (stmt)
: gimple_assign_lhs (stmt));
}
/* Callback for htab_traverse. Create the initialization statement
for reduction described in SLOT, and place it at the preheader of
the loop described in DATA. */
int
initialize_reductions (reduction_info **slot, class loop *loop)
{
tree init;
tree type, arg;
edge e;
struct reduction_info *const reduc = *slot;
/* Create initialization in preheader:
reduction_variable = initialization value of reduction. */
/* In the phi node at the header, replace the argument coming
from the preheader with the reduction initialization value. */
/* Initialize the reduction. */
type = TREE_TYPE (PHI_RESULT (reduc->reduc_phi));
init = omp_reduction_init_op (gimple_location (reduc->reduc_stmt),
reduc->reduction_code, type);
reduc->init = init;
/* Replace the argument representing the initialization value
with the initialization value for the reduction (neutral
element for the particular operation, e.g. 0 for PLUS_EXPR,
1 for MULT_EXPR, etc).
Keep the old value in a new variable "reduction_initial",
that will be taken in consideration after the parallel
computing is done. */
e = loop_preheader_edge (loop);
arg = PHI_ARG_DEF_FROM_EDGE (reduc->reduc_phi, e);
/* Create new variable to hold the initial value. */
SET_USE (PHI_ARG_DEF_PTR_FROM_EDGE
(reduc->reduc_phi, loop_preheader_edge (loop)), init);
reduc->initial_value = arg;
return 1;
}
struct elv_data
{
struct walk_stmt_info info;
edge entry;
int_tree_htab_type *decl_address;
gimple_stmt_iterator *gsi;
bool changed;
bool reset;
};
/* Eliminates references to local variables in *TP out of the single
entry single exit region starting at DTA->ENTRY.
DECL_ADDRESS contains addresses of the references that had their
address taken already. If the expression is changed, CHANGED is
set to true. Callback for walk_tree. */
static tree
eliminate_local_variables_1 (tree *tp, int *walk_subtrees, void *data)
{
struct elv_data *const dta = (struct elv_data *) data;
tree t = *tp, var, addr, addr_type, type, obj;
if (DECL_P (t))
{
*walk_subtrees = 0;
if (!SSA_VAR_P (t) || DECL_EXTERNAL (t))
return NULL_TREE;
type = TREE_TYPE (t);
addr_type = build_pointer_type (type);
addr = take_address_of (t, addr_type, dta->entry, dta->decl_address,
dta->gsi);
if (dta->gsi == NULL && addr == NULL_TREE)
{
dta->reset = true;
return NULL_TREE;
}
*tp = build_simple_mem_ref (addr);
dta->changed = true;
return NULL_TREE;
}
if (TREE_CODE (t) == ADDR_EXPR)
{
/* ADDR_EXPR may appear in two contexts:
-- as a gimple operand, when the address taken is a function invariant
-- as gimple rhs, when the resulting address in not a function
invariant
We do not need to do anything special in the latter case (the base of
the memory reference whose address is taken may be replaced in the
DECL_P case). The former case is more complicated, as we need to
ensure that the new address is still a gimple operand. Thus, it
is not sufficient to replace just the base of the memory reference --
we need to move the whole computation of the address out of the
loop. */
if (!is_gimple_val (t))
return NULL_TREE;
*walk_subtrees = 0;
obj = TREE_OPERAND (t, 0);
var = get_base_address (obj);
if (!var || !SSA_VAR_P (var) || DECL_EXTERNAL (var))
return NULL_TREE;
addr_type = TREE_TYPE (t);
addr = take_address_of (obj, addr_type, dta->entry, dta->decl_address,
dta->gsi);
if (dta->gsi == NULL && addr == NULL_TREE)
{
dta->reset = true;
return NULL_TREE;
}
*tp = addr;
dta->changed = true;
return NULL_TREE;
}
if (!EXPR_P (t))
*walk_subtrees = 0;
return NULL_TREE;
}
/* Moves the references to local variables in STMT at *GSI out of the single
entry single exit region starting at ENTRY. DECL_ADDRESS contains
addresses of the references that had their address taken
already. */
static void
eliminate_local_variables_stmt (edge entry, gimple_stmt_iterator *gsi,
int_tree_htab_type *decl_address)
{
struct elv_data dta;
gimple *stmt = gsi_stmt (*gsi);
memset (&dta.info, '\0', sizeof (dta.info));
dta.entry = entry;
dta.decl_address = decl_address;
dta.changed = false;
dta.reset = false;
if (gimple_debug_bind_p (stmt))
{
dta.gsi = NULL;
walk_tree (gimple_debug_bind_get_value_ptr (stmt),
eliminate_local_variables_1, &dta.info, NULL);
if (dta.reset)
{
gimple_debug_bind_reset_value (stmt);
dta.changed = true;
}
}
else if (gimple_clobber_p (stmt))
{
unlink_stmt_vdef (stmt);
stmt = gimple_build_nop ();
gsi_replace (gsi, stmt, false);
dta.changed = true;
}
else
{
dta.gsi = gsi;
walk_gimple_op (stmt, eliminate_local_variables_1, &dta.info);
}
if (dta.changed)
update_stmt (stmt);
}
/* Eliminates the references to local variables from the single entry
single exit region between the ENTRY and EXIT edges.
This includes:
1) Taking address of a local variable -- these are moved out of the
region (and temporary variable is created to hold the address if
necessary).
2) Dereferencing a local variable -- these are replaced with indirect
references. */
static void
eliminate_local_variables (edge entry, edge exit)
{
basic_block bb;
auto_vec<basic_block, 3> body;
unsigned i;
gimple_stmt_iterator gsi;
bool has_debug_stmt = false;
int_tree_htab_type decl_address (10);
basic_block entry_bb = entry->src;
basic_block exit_bb = exit->dest;
gather_blocks_in_sese_region (entry_bb, exit_bb, &body);
FOR_EACH_VEC_ELT (body, i, bb)
if (bb != entry_bb && bb != exit_bb)
{
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
if (is_gimple_debug (gsi_stmt (gsi)))
{
if (gimple_debug_bind_p (gsi_stmt (gsi)))
has_debug_stmt = true;
}
else
eliminate_local_variables_stmt (entry, &gsi, &decl_address);
}
if (has_debug_stmt)
FOR_EACH_VEC_ELT (body, i, bb)
if (bb != entry_bb && bb != exit_bb)
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
if (gimple_debug_bind_p (gsi_stmt (gsi)))
eliminate_local_variables_stmt (entry, &gsi, &decl_address);
}
/* Returns true if expression EXPR is not defined between ENTRY and
EXIT, i.e. if all its operands are defined outside of the region. */
static bool
expr_invariant_in_region_p (edge entry, edge exit, tree expr)
{
basic_block entry_bb = entry->src;
basic_block exit_bb = exit->dest;
basic_block def_bb;
if (is_gimple_min_invariant (expr))
return true;
if (TREE_CODE (expr) == SSA_NAME)
{
def_bb = gimple_bb (SSA_NAME_DEF_STMT (expr));
if (def_bb
&& dominated_by_p (CDI_DOMINATORS, def_bb, entry_bb)
&& !dominated_by_p (CDI_DOMINATORS, def_bb, exit_bb))
return false;
return true;
}
return false;
}
/* If COPY_NAME_P is true, creates and returns a duplicate of NAME.
The copies are stored to NAME_COPIES, if NAME was already duplicated,
its duplicate stored in NAME_COPIES is returned.
Regardless of COPY_NAME_P, the decl used as a base of the ssa name is also
duplicated, storing the copies in DECL_COPIES. */
static tree
separate_decls_in_region_name (tree name, name_to_copy_table_type *name_copies,
int_tree_htab_type *decl_copies,
bool copy_name_p)
{
tree copy, var, var_copy;
unsigned idx, uid, nuid;
struct int_tree_map ielt;
struct name_to_copy_elt elt, *nelt;
name_to_copy_elt **slot;
int_tree_map *dslot;
if (TREE_CODE (name) != SSA_NAME)
return name;
idx = SSA_NAME_VERSION (name);
elt.version = idx;
slot = name_copies->find_slot_with_hash (&elt, idx,
copy_name_p ? INSERT : NO_INSERT);
if (slot && *slot)
return (*slot)->new_name;
if (copy_name_p)
{
copy = duplicate_ssa_name (name, NULL);
nelt = XNEW (struct name_to_copy_elt);
nelt->version = idx;
nelt->new_name = copy;
nelt->field = NULL_TREE;
*slot = nelt;
}
else
{
gcc_assert (!slot);
copy = name;
}
var = SSA_NAME_VAR (name);
if (!var)
return copy;
uid = DECL_UID (var);
ielt.uid = uid;
dslot = decl_copies->find_slot_with_hash (ielt, uid, INSERT);
if (!dslot->to)
{
var_copy = create_tmp_var (TREE_TYPE (var), get_name (var));
DECL_NOT_GIMPLE_REG_P (var_copy) = DECL_NOT_GIMPLE_REG_P (var);
dslot->uid = uid;
dslot->to = var_copy;
/* Ensure that when we meet this decl next time, we won't duplicate
it again. */
nuid = DECL_UID (var_copy);
ielt.uid = nuid;
dslot = decl_copies->find_slot_with_hash (ielt, nuid, INSERT);
gcc_assert (!dslot->to);
dslot->uid = nuid;
dslot->to = var_copy;
}
else
var_copy = dslot->to;
replace_ssa_name_symbol (copy, var_copy);
return copy;
}
/* Finds the ssa names used in STMT that are defined outside the
region between ENTRY and EXIT and replaces such ssa names with
their duplicates. The duplicates are stored to NAME_COPIES. Base
decls of all ssa names used in STMT (including those defined in
LOOP) are replaced with the new temporary variables; the
replacement decls are stored in DECL_COPIES. */
static void
separate_decls_in_region_stmt (edge entry, edge exit, gimple *stmt,
name_to_copy_table_type *name_copies,
int_tree_htab_type *decl_copies)
{
use_operand_p use;
def_operand_p def;
ssa_op_iter oi;
tree name, copy;
bool copy_name_p;
FOR_EACH_PHI_OR_STMT_DEF (def, stmt, oi, SSA_OP_DEF)
{
name = DEF_FROM_PTR (def);
gcc_assert (TREE_CODE (name) == SSA_NAME);
copy = separate_decls_in_region_name (name, name_copies, decl_copies,
false);
gcc_assert (copy == name);
}
FOR_EACH_PHI_OR_STMT_USE (use, stmt, oi, SSA_OP_USE)
{
name = USE_FROM_PTR (use);
if (TREE_CODE (name) != SSA_NAME)
continue;
copy_name_p = expr_invariant_in_region_p (entry, exit, name);
copy = separate_decls_in_region_name (name, name_copies, decl_copies,
copy_name_p);
SET_USE (use, copy);
}
}
/* Finds the ssa names used in STMT that are defined outside the
region between ENTRY and EXIT and replaces such ssa names with
their duplicates. The duplicates are stored to NAME_COPIES. Base
decls of all ssa names used in STMT (including those defined in
LOOP) are replaced with the new temporary variables; the
replacement decls are stored in DECL_COPIES. */
static bool
separate_decls_in_region_debug (gimple *stmt,
name_to_copy_table_type *name_copies,
int_tree_htab_type *decl_copies)
{
use_operand_p use;
ssa_op_iter oi;
tree var, name;
struct int_tree_map ielt;
struct name_to_copy_elt elt;
name_to_copy_elt **slot;
int_tree_map *dslot;
if (gimple_debug_bind_p (stmt))
var = gimple_debug_bind_get_var (stmt);
else if (gimple_debug_source_bind_p (stmt))
var = gimple_debug_source_bind_get_var (stmt);
else
return true;
if (TREE_CODE (var) == DEBUG_EXPR_DECL || TREE_CODE (var) == LABEL_DECL)
return true;
gcc_assert (DECL_P (var) && SSA_VAR_P (var));
ielt.uid = DECL_UID (var);
dslot = decl_copies->find_slot_with_hash (ielt, ielt.uid, NO_INSERT);
if (!dslot)
return true;
if (gimple_debug_bind_p (stmt))
gimple_debug_bind_set_var (stmt, dslot->to);
else if (gimple_debug_source_bind_p (stmt))
gimple_debug_source_bind_set_var (stmt, dslot->to);
FOR_EACH_PHI_OR_STMT_USE (use, stmt, oi, SSA_OP_USE)
{
name = USE_FROM_PTR (use);
if (TREE_CODE (name) != SSA_NAME)
continue;
elt.version = SSA_NAME_VERSION (name);
slot = name_copies->find_slot_with_hash (&elt, elt.version, NO_INSERT);
if (!slot)
{
gimple_debug_bind_reset_value (stmt);
update_stmt (stmt);
break;
}
SET_USE (use, (*slot)->new_name);
}
return false;
}
/* Callback for htab_traverse. Adds a field corresponding to the reduction
specified in SLOT. The type is passed in DATA. */
int
add_field_for_reduction (reduction_info **slot, tree type)
{
struct reduction_info *const red = *slot;
tree var = reduc_stmt_res (red->reduc_stmt);
tree field = build_decl (gimple_location (red->reduc_stmt), FIELD_DECL,
SSA_NAME_IDENTIFIER (var), TREE_TYPE (var));
insert_field_into_struct (type, field);
red->field = field;
return 1;
}
/* Callback for htab_traverse. Adds a field corresponding to a ssa name
described in SLOT. The type is passed in DATA. */
int
add_field_for_name (name_to_copy_elt **slot, tree type)
{
struct name_to_copy_elt *const elt = *slot;
tree name = ssa_name (elt->version);
tree field = build_decl (UNKNOWN_LOCATION,
FIELD_DECL, SSA_NAME_IDENTIFIER (name),
TREE_TYPE (name));
insert_field_into_struct (type, field);
elt->field = field;
return 1;
}
/* Callback for htab_traverse. A local result is the intermediate result
computed by a single
thread, or the initial value in case no iteration was executed.
This function creates a phi node reflecting these values.
The phi's result will be stored in NEW_PHI field of the
reduction's data structure. */
int
create_phi_for_local_result (reduction_info **slot, class loop *loop)
{
struct reduction_info *const reduc = *slot;
edge e;
gphi *new_phi;
basic_block store_bb, continue_bb;
tree local_res;
location_t locus;
/* STORE_BB is the block where the phi
should be stored. It is the destination of the loop exit.
(Find the fallthru edge from GIMPLE_OMP_CONTINUE). */
continue_bb = single_pred (loop->latch);
store_bb = FALLTHRU_EDGE (continue_bb)->dest;
/* STORE_BB has two predecessors. One coming from the loop
(the reduction's result is computed at the loop),
and another coming from a block preceding the loop,
when no iterations
are executed (the initial value should be taken). */
if (EDGE_PRED (store_bb, 0) == FALLTHRU_EDGE (continue_bb))
e = EDGE_PRED (store_bb, 1);
else
e = EDGE_PRED (store_bb, 0);
tree lhs = reduc_stmt_res (reduc->reduc_stmt);
local_res = copy_ssa_name (lhs);
locus = gimple_location (reduc->reduc_stmt);
new_phi = create_phi_node (local_res, store_bb);
add_phi_arg (new_phi, reduc->init, e, locus);
add_phi_arg (new_phi, lhs, FALLTHRU_EDGE (continue_bb), locus);
reduc->new_phi = new_phi;
return 1;
}
struct clsn_data
{
tree store;
tree load;
basic_block store_bb;
basic_block load_bb;
};
/* Callback for htab_traverse. Create an atomic instruction for the
reduction described in SLOT.
DATA annotates the place in memory the atomic operation relates to,
and the basic block it needs to be generated in. */
int
create_call_for_reduction_1 (reduction_info **slot, struct clsn_data *clsn_data)
{
struct reduction_info *const reduc = *slot;
gimple_stmt_iterator gsi;
tree type = TREE_TYPE (PHI_RESULT (reduc->reduc_phi));
tree load_struct;
basic_block bb;
basic_block new_bb;
edge e;
tree t, addr, ref, x;
tree tmp_load, name;
gimple *load;
if (reduc->reduc_addr == NULL_TREE)
{
load_struct = build_simple_mem_ref (clsn_data->load);
t = build3 (COMPONENT_REF, type, load_struct, reduc->field, NULL_TREE);
addr = build_addr (t);
}
else
{
/* Set the address for the atomic store. */
addr = reduc->reduc_addr;
/* Remove the non-atomic store '*addr = sum'. */
tree res = PHI_RESULT (reduc->keep_res);
use_operand_p use_p;
gimple *stmt;
bool single_use_p = single_imm_use (res, &use_p, &stmt);
gcc_assert (single_use_p);
replace_uses_by (gimple_vdef (stmt),
gimple_vuse (stmt));
gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
gsi_remove (&gsi, true);
}
/* Create phi node. */
bb = clsn_data->load_bb;
gsi = gsi_last_bb (bb);
e = split_block (bb, gsi_stmt (gsi));
new_bb = e->dest;
tmp_load = create_tmp_var (TREE_TYPE (TREE_TYPE (addr)));
tmp_load = make_ssa_name (tmp_load);
load = gimple_build_omp_atomic_load (tmp_load, addr,
OMP_MEMORY_ORDER_RELAXED);
SSA_NAME_DEF_STMT (tmp_load) = load;
gsi = gsi_start_bb (new_bb);
gsi_insert_after (&gsi, load, GSI_NEW_STMT);
e = split_block (new_bb, load);
new_bb = e->dest;
gsi = gsi_start_bb (new_bb);
ref = tmp_load;
x = fold_build2 (reduc->reduction_code,
TREE_TYPE (PHI_RESULT (reduc->new_phi)), ref,
PHI_RESULT (reduc->new_phi));
name = force_gimple_operand_gsi (&gsi, x, true, NULL_TREE, true,
GSI_CONTINUE_LINKING);
gimple *store = gimple_build_omp_atomic_store (name,
OMP_MEMORY_ORDER_RELAXED);
gsi_insert_after (&gsi, store, GSI_NEW_STMT);
return 1;
}
/* Create the atomic operation at the join point of the threads.
REDUCTION_LIST describes the reductions in the LOOP.
LD_ST_DATA describes the shared data structure where
shared data is stored in and loaded from. */
static void
create_call_for_reduction (class loop *loop,
reduction_info_table_type *reduction_list,
struct clsn_data *ld_st_data)
{
reduction_list->traverse <class loop *, create_phi_for_local_result> (loop);
/* Find the fallthru edge from GIMPLE_OMP_CONTINUE. */
basic_block continue_bb = single_pred (loop->latch);
ld_st_data->load_bb = FALLTHRU_EDGE (continue_bb)->dest;
reduction_list
->traverse <struct clsn_data *, create_call_for_reduction_1> (ld_st_data);
}
/* Callback for htab_traverse. Loads the final reduction value at the
join point of all threads, and inserts it in the right place. */
int
create_loads_for_reductions (reduction_info **slot, struct clsn_data *clsn_data)
{
struct reduction_info *const red = *slot;
gimple *stmt;
gimple_stmt_iterator gsi;
tree type = TREE_TYPE (reduc_stmt_res (red->reduc_stmt));
tree load_struct;
tree name;
tree x;
/* If there's no exit phi, the result of the reduction is unused. */
if (red->keep_res == NULL)
return 1;
gsi = gsi_after_labels (clsn_data->load_bb);
load_struct = build_simple_mem_ref (clsn_data->load);
load_struct = build3 (COMPONENT_REF, type, load_struct, red->field,
NULL_TREE);
x = load_struct;
name = PHI_RESULT (red->keep_res);
stmt = gimple_build_assign (name, x);
gsi_insert_after (&gsi, stmt, GSI_NEW_STMT);
for (gsi = gsi_start_phis (gimple_bb (red->keep_res));
!gsi_end_p (gsi); gsi_next (&gsi))
if (gsi_stmt (gsi) == red->keep_res)
{
remove_phi_node (&gsi, false);
return 1;
}
gcc_unreachable ();
}
/* Load the reduction result that was stored in LD_ST_DATA.
REDUCTION_LIST describes the list of reductions that the
loads should be generated for. */
static void
create_final_loads_for_reduction (reduction_info_table_type *reduction_list,
struct clsn_data *ld_st_data)
{
gimple_stmt_iterator gsi;
tree t;
gimple *stmt;
gsi = gsi_after_labels (ld_st_data->load_bb);
t = build_fold_addr_expr (ld_st_data->store);
stmt = gimple_build_assign (ld_st_data->load, t);
gsi_insert_before (&gsi, stmt, GSI_NEW_STMT);
reduction_list
->traverse <struct clsn_data *, create_loads_for_reductions> (ld_st_data);
}
/* Callback for htab_traverse. Store the neutral value for the
particular reduction's operation, e.g. 0 for PLUS_EXPR,
1 for MULT_EXPR, etc. into the reduction field.
The reduction is specified in SLOT. The store information is
passed in DATA. */
int
create_stores_for_reduction (reduction_info **slot, struct clsn_data *clsn_data)
{
struct reduction_info *const red = *slot;
tree t;
gimple *stmt;
gimple_stmt_iterator gsi;
tree type = TREE_TYPE (reduc_stmt_res (red->reduc_stmt));
gsi = gsi_last_bb (clsn_data->store_bb);
t = build3 (COMPONENT_REF, type, clsn_data->store, red->field, NULL_TREE);
stmt = gimple_build_assign (t, red->initial_value);
gsi_insert_after (&gsi, stmt, GSI_NEW_STMT);
return 1;
}
/* Callback for htab_traverse. Creates loads to a field of LOAD in LOAD_BB and
store to a field of STORE in STORE_BB for the ssa name and its duplicate
specified in SLOT. */
int
create_loads_and_stores_for_name (name_to_copy_elt **slot,
struct clsn_data *clsn_data)
{
struct name_to_copy_elt *const elt = *slot;
tree t;
gimple *stmt;
gimple_stmt_iterator gsi;
tree type = TREE_TYPE (elt->new_name);
tree load_struct;
gsi = gsi_last_bb (clsn_data->store_bb);
t = build3 (COMPONENT_REF, type, clsn_data->store, elt->field, NULL_TREE);
stmt = gimple_build_assign (t, ssa_name (elt->version));
gsi_insert_after (&gsi, stmt, GSI_NEW_STMT);
gsi = gsi_last_bb (clsn_data->load_bb);
load_struct = build_simple_mem_ref (clsn_data->load);
t = build3 (COMPONENT_REF, type, load_struct, elt->field, NULL_TREE);
stmt = gimple_build_assign (elt->new_name, t);
gsi_insert_after (&gsi, stmt, GSI_NEW_STMT);
return 1;
}
/* Moves all the variables used in LOOP and defined outside of it (including
the initial values of loop phi nodes, and *PER_THREAD if it is a ssa
name) to a structure created for this purpose. The code
while (1)
{
use (a);
use (b);
}
is transformed this way:
bb0:
old.a = a;
old.b = b;
bb1:
a' = new->a;
b' = new->b;
while (1)
{
use (a');
use (b');
}
`old' is stored to *ARG_STRUCT and `new' is stored to NEW_ARG_STRUCT. The
pointer `new' is intentionally not initialized (the loop will be split to a
separate function later, and `new' will be initialized from its arguments).
LD_ST_DATA holds information about the shared data structure used to pass
information among the threads. It is initialized here, and
gen_parallel_loop will pass it to create_call_for_reduction that
needs this information. REDUCTION_LIST describes the reductions
in LOOP. */
static void
separate_decls_in_region (edge entry, edge exit,
reduction_info_table_type *reduction_list,
tree *arg_struct, tree *new_arg_struct,
struct clsn_data *ld_st_data)
{
basic_block bb1 = split_edge (entry);
basic_block bb0 = single_pred (bb1);
name_to_copy_table_type name_copies (10);
int_tree_htab_type decl_copies (10);
unsigned i;
tree type, type_name, nvar;
gimple_stmt_iterator gsi;
struct clsn_data clsn_data;
auto_vec<basic_block, 3> body;
basic_block bb;
basic_block entry_bb = bb1;
basic_block exit_bb = exit->dest;
bool has_debug_stmt = false;
entry = single_succ_edge (entry_bb);
gather_blocks_in_sese_region (entry_bb, exit_bb, &body);
FOR_EACH_VEC_ELT (body, i, bb)
{
if (bb != entry_bb && bb != exit_bb)
{
for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
separate_decls_in_region_stmt (entry, exit, gsi_stmt (gsi),
&name_copies, &decl_copies);
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
gimple *stmt = gsi_stmt (gsi);
if (is_gimple_debug (stmt))
has_debug_stmt = true;
else
separate_decls_in_region_stmt (entry, exit, stmt,
&name_copies, &decl_copies);
}
}
}
/* Now process debug bind stmts. We must not create decls while
processing debug stmts, so we defer their processing so as to
make sure we will have debug info for as many variables as
possible (all of those that were dealt with in the loop above),
and discard those for which we know there's nothing we can
do. */
if (has_debug_stmt)
FOR_EACH_VEC_ELT (body, i, bb)
if (bb != entry_bb && bb != exit_bb)
{
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi);)
{
gimple *stmt = gsi_stmt (gsi);
if (is_gimple_debug (stmt))
{
if (separate_decls_in_region_debug (stmt, &name_copies,
&decl_copies))
{
gsi_remove (&gsi, true);
continue;
}
}
gsi_next (&gsi);
}
}
if (name_copies.is_empty () && reduction_list->is_empty ())
{
/* It may happen that there is nothing to copy (if there are only
loop carried and external variables in the loop). */
*arg_struct = NULL;
*new_arg_struct = NULL;
}
else
{
/* Create the type for the structure to store the ssa names to. */
type = lang_hooks.types.make_type (RECORD_TYPE);
type_name = build_decl (UNKNOWN_LOCATION,
TYPE_DECL, create_tmp_var_name (".paral_data"),
type);
TYPE_NAME (type) = type_name;
name_copies.traverse <tree, add_field_for_name> (type);
if (reduction_list && !reduction_list->is_empty ())
{
/* Create the fields for reductions. */
reduction_list->traverse <tree, add_field_for_reduction> (type);
}
layout_type (type);
/* Create the loads and stores. */
*arg_struct = create_tmp_var (type, ".paral_data_store");
nvar = create_tmp_var (build_pointer_type (type), ".paral_data_load");
*new_arg_struct = make_ssa_name (nvar);
ld_st_data->store = *arg_struct;
ld_st_data->load = *new_arg_struct;
ld_st_data->store_bb = bb0;
ld_st_data->load_bb = bb1;
name_copies
.traverse <struct clsn_data *, create_loads_and_stores_for_name>
(ld_st_data);
/* Load the calculation from memory (after the join of the threads). */
if (reduction_list && !reduction_list->is_empty ())
{
reduction_list
->traverse <struct clsn_data *, create_stores_for_reduction>
(ld_st_data);
clsn_data.load = make_ssa_name (nvar);
clsn_data.load_bb = exit->dest;
clsn_data.store = ld_st_data->store;
create_final_loads_for_reduction (reduction_list, &clsn_data);
}
}
}
/* Returns true if FN was created to run in parallel. */
bool
parallelized_function_p (tree fndecl)
{
cgraph_node *node = cgraph_node::get (fndecl);
gcc_assert (node != NULL);
return node->parallelized_function;
}
/* Creates and returns an empty function that will receive the body of
a parallelized loop. */
static tree
create_loop_fn (location_t loc)
{
char buf[100];
char *tname;
tree decl, type, name, t;
struct function *act_cfun = cfun;
static unsigned loopfn_num;
loc = LOCATION_LOCUS (loc);
snprintf (buf, 100, "%s.$loopfn", current_function_name ());
ASM_FORMAT_PRIVATE_NAME (tname, buf, loopfn_num++);
clean_symbol_name (tname);
name = get_identifier (tname);
type = build_function_type_list (void_type_node, ptr_type_node, NULL_TREE);
decl = build_decl (loc, FUNCTION_DECL, name, type);
TREE_STATIC (decl) = 1;
TREE_USED (decl) = 1;
DECL_ARTIFICIAL (decl) = 1;
DECL_IGNORED_P (decl) = 0;
TREE_PUBLIC (decl) = 0;
DECL_UNINLINABLE (decl) = 1;
DECL_EXTERNAL (decl) = 0;
DECL_CONTEXT (decl) = NULL_TREE;
DECL_INITIAL (decl) = make_node (BLOCK);
BLOCK_SUPERCONTEXT (DECL_INITIAL (decl)) = decl;
t = build_decl (loc, RESULT_DECL, NULL_TREE, void_type_node);
DECL_ARTIFICIAL (t) = 1;
DECL_IGNORED_P (t) = 1;
DECL_RESULT (decl) = t;
t = build_decl (loc, PARM_DECL, get_identifier (".paral_data_param"),
ptr_type_node);
DECL_ARTIFICIAL (t) = 1;
DECL_ARG_TYPE (t) = ptr_type_node;
DECL_CONTEXT (t) = decl;
TREE_USED (t) = 1;
DECL_ARGUMENTS (decl) = t;
allocate_struct_function (decl, false);
/* The call to allocate_struct_function clobbers CFUN, so we need to restore
it. */
set_cfun (act_cfun);
return decl;
}
/* Replace uses of NAME by VAL in block BB. */
static void
replace_uses_in_bb_by (tree name, tree val, basic_block bb)
{
gimple *use_stmt;
imm_use_iterator imm_iter;
FOR_EACH_IMM_USE_STMT (use_stmt, imm_iter, name)
{
if (gimple_bb (use_stmt) != bb)
continue;
use_operand_p use_p;
FOR_EACH_IMM_USE_ON_STMT (use_p, imm_iter)
SET_USE (use_p, val);
}
}
/* Do transformation from:
<bb preheader>:
...
goto <bb header>
<bb header>:
ivtmp_a = PHI <ivtmp_init (preheader), ivtmp_b (latch)>
sum_a = PHI <sum_init (preheader), sum_b (latch)>
...
use (ivtmp_a)
...
sum_b = sum_a + sum_update
...
if (ivtmp_a < n)
goto <bb latch>;
else
goto <bb exit>;
<bb latch>:
ivtmp_b = ivtmp_a + 1;
goto <bb header>
<bb exit>:
sum_z = PHI <sum_b (cond[1]), ...>
[1] Where <bb cond> is single_pred (bb latch); In the simplest case,
that's <bb header>.
to:
<bb preheader>:
...
goto <bb newheader>
<bb header>:
ivtmp_a = PHI <ivtmp_c (latch)>
sum_a = PHI <sum_c (latch)>
...
use (ivtmp_a)
...
sum_b = sum_a + sum_update
...
goto <bb latch>;
<bb newheader>:
ivtmp_c = PHI <ivtmp_init (preheader), ivtmp_b (latch)>
sum_c = PHI <sum_init (preheader), sum_b (latch)>
if (ivtmp_c < n + 1)
goto <bb header>;
else
goto <bb newexit>;
<bb latch>:
ivtmp_b = ivtmp_a + 1;
goto <bb newheader>
<bb newexit>:
sum_y = PHI <sum_c (newheader)>
<bb exit>:
sum_z = PHI <sum_y (newexit), ...>
In unified diff format:
<bb preheader>:
...
- goto <bb header>
+ goto <bb newheader>
<bb header>:
- ivtmp_a = PHI <ivtmp_init (preheader), ivtmp_b (latch)>
- sum_a = PHI <sum_init (preheader), sum_b (latch)>
+ ivtmp_a = PHI <ivtmp_c (latch)>
+ sum_a = PHI <sum_c (latch)>
...
use (ivtmp_a)
...
sum_b = sum_a + sum_update
...
- if (ivtmp_a < n)
- goto <bb latch>;
+ goto <bb latch>;
+
+ <bb newheader>:
+ ivtmp_c = PHI <ivtmp_init (preheader), ivtmp_b (latch)>
+ sum_c = PHI <sum_init (preheader), sum_b (latch)>
+ if (ivtmp_c < n + 1)
+ goto <bb header>;
else
goto <bb exit>;
<bb latch>:
ivtmp_b = ivtmp_a + 1;
- goto <bb header>
+ goto <bb newheader>
+ <bb newexit>:
+ sum_y = PHI <sum_c (newheader)>
<bb exit>:
- sum_z = PHI <sum_b (cond[1]), ...>
+ sum_z = PHI <sum_y (newexit), ...>
Note: the example does not show any virtual phis, but these are handled more
or less as reductions.
Moves the exit condition of LOOP to the beginning of its header.
REDUCTION_LIST describes the reductions in LOOP. BOUND is the new loop
bound. */
static void
transform_to_exit_first_loop_alt (class loop *loop,
reduction_info_table_type *reduction_list,
tree bound)
{
basic_block header = loop->header;
basic_block latch = loop->latch;
edge exit = single_dom_exit (loop);
basic_block exit_block = exit->dest;
gcond *cond_stmt = as_a <gcond *> (last_stmt (exit->src));
tree control = gimple_cond_lhs (cond_stmt);
edge e;
/* Rewriting virtuals into loop-closed ssa normal form makes this
transformation simpler. It also ensures that the virtuals are in
loop-closed ssa normal from after the transformation, which is required by
create_parallel_loop. */
rewrite_virtuals_into_loop_closed_ssa (loop);
/* Create the new_header block. */
basic_block new_header = split_block_before_cond_jump (exit->src);
edge edge_at_split = single_pred_edge (new_header);
/* Redirect entry edge to new_header. */
edge entry = loop_preheader_edge (loop);
e = redirect_edge_and_branch (entry, new_header);
gcc_assert (e == entry);
/* Redirect post_inc_edge to new_header. */
edge post_inc_edge = single_succ_edge (latch);
e = redirect_edge_and_branch (post_inc_edge, new_header);
gcc_assert (e == post_inc_edge);
/* Redirect post_cond_edge to header. */
edge post_cond_edge = single_pred_edge (latch);
e = redirect_edge_and_branch (post_cond_edge, header);
gcc_assert (e == post_cond_edge);
/* Redirect edge_at_split to latch. */
e = redirect_edge_and_branch (edge_at_split, latch);
gcc_assert (e == edge_at_split);
/* Set the new loop bound. */
gimple_cond_set_rhs (cond_stmt, bound);
update_stmt (cond_stmt);
/* Repair the ssa. */
vec<edge_var_map> *v = redirect_edge_var_map_vector (post_inc_edge);
edge_var_map *vm;
gphi_iterator gsi;
int i;
for (gsi = gsi_start_phis (header), i = 0;
!gsi_end_p (gsi) && v->iterate (i, &vm);
gsi_next (&gsi), i++)
{
gphi *phi = gsi.phi ();
tree res_a = PHI_RESULT (phi);
/* Create new phi. */
tree res_c = copy_ssa_name (res_a, phi);
gphi *nphi = create_phi_node (res_c, new_header);
/* Replace ivtmp_a with ivtmp_c in condition 'if (ivtmp_a < n)'. */
replace_uses_in_bb_by (res_a, res_c, new_header);
/* Replace ivtmp/sum_b with ivtmp/sum_c in header phi. */
add_phi_arg (phi, res_c, post_cond_edge, UNKNOWN_LOCATION);
/* Replace sum_b with sum_c in exit phi. */
tree res_b = redirect_edge_var_map_def (vm);
replace_uses_in_bb_by (res_b, res_c, exit_block);
struct reduction_info *red = reduction_phi (reduction_list, phi);
gcc_assert (virtual_operand_p (res_a)
|| res_a == control
|| red != NULL);
if (red)
{
/* Register the new reduction phi. */
red->reduc_phi = nphi;
gimple_set_uid (red->reduc_phi, red->reduc_version);
}
}
gcc_assert (gsi_end_p (gsi) && !v->iterate (i, &vm));
/* Set the preheader argument of the new phis to ivtmp/sum_init. */
flush_pending_stmts (entry);
/* Set the latch arguments of the new phis to ivtmp/sum_b. */
flush_pending_stmts (post_inc_edge);
basic_block new_exit_block = NULL;
if (!single_pred_p (exit->dest))
{
/* Create a new empty exit block, inbetween the new loop header and the
old exit block. The function separate_decls_in_region needs this block
to insert code that is active on loop exit, but not any other path. */
new_exit_block = split_edge (exit);
}
/* Insert and register the reduction exit phis. */
for (gphi_iterator gsi = gsi_start_phis (exit_block);
!gsi_end_p (gsi);
gsi_next (&gsi))
{
gphi *phi = gsi.phi ();
gphi *nphi = NULL;
tree res_z = PHI_RESULT (phi);
tree res_c;
if (new_exit_block != NULL)
{
/* Now that we have a new exit block, duplicate the phi of the old
exit block in the new exit block to preserve loop-closed ssa. */
edge succ_new_exit_block = single_succ_edge (new_exit_block);
edge pred_new_exit_block = single_pred_edge (new_exit_block);
tree res_y = copy_ssa_name (res_z, phi);
nphi = create_phi_node (res_y, new_exit_block);
res_c = PHI_ARG_DEF_FROM_EDGE (phi, succ_new_exit_block);
add_phi_arg (nphi, res_c, pred_new_exit_block, UNKNOWN_LOCATION);
add_phi_arg (phi, res_y, succ_new_exit_block, UNKNOWN_LOCATION);
}
else
res_c = PHI_ARG_DEF_FROM_EDGE (phi, exit);
if (virtual_operand_p (res_z))
continue;
gimple *reduc_phi = SSA_NAME_DEF_STMT (res_c);
struct reduction_info *red = reduction_phi (reduction_list, reduc_phi);
if (red != NULL)
red->keep_res = (nphi != NULL
? nphi
: phi);
}
/* We're going to cancel the loop at the end of gen_parallel_loop, but until
then we're still using some fields, so only bother about fields that are
still used: header and latch.
The loop has a new header bb, so we update it. The latch bb stays the
same. */
loop->header = new_header;
/* Recalculate dominance info. */
free_dominance_info (CDI_DOMINATORS);
calculate_dominance_info (CDI_DOMINATORS);
checking_verify_ssa (true, true);
}
/* Tries to moves the exit condition of LOOP to the beginning of its header
without duplication of the loop body. NIT is the number of iterations of the
loop. REDUCTION_LIST describes the reductions in LOOP. Return true if
transformation is successful. */
static bool
try_transform_to_exit_first_loop_alt (class loop *loop,
reduction_info_table_type *reduction_list,
tree nit)
{
/* Check whether the latch contains a single statement. */
if (!gimple_seq_nondebug_singleton_p (bb_seq (loop->latch)))
return false;
/* Check whether the latch contains no phis. */
if (phi_nodes (loop->latch) != NULL)
return false;
/* Check whether the latch contains the loop iv increment. */
edge back = single_succ_edge (loop->latch);
edge exit = single_dom_exit (loop);
gcond *cond_stmt = as_a <gcond *> (last_stmt (exit->src));
tree control = gimple_cond_lhs (cond_stmt);
gphi *phi = as_a <gphi *> (SSA_NAME_DEF_STMT (control));
tree inc_res = gimple_phi_arg_def (phi, back->dest_idx);
if (gimple_bb (SSA_NAME_DEF_STMT (inc_res)) != loop->latch)
return false;
/* Check whether there's no code between the loop condition and the latch. */
if (!single_pred_p (loop->latch)
|| single_pred (loop->latch) != exit->src)
return false;
tree alt_bound = NULL_TREE;
tree nit_type = TREE_TYPE (nit);
/* Figure out whether nit + 1 overflows. */
if (TREE_CODE (nit) == INTEGER_CST)
{
if (!tree_int_cst_equal (nit, TYPE_MAX_VALUE (nit_type)))
{
alt_bound = fold_build2_loc (UNKNOWN_LOCATION, PLUS_EXPR, nit_type,
nit, build_one_cst (nit_type));
gcc_assert (TREE_CODE (alt_bound) == INTEGER_CST);
transform_to_exit_first_loop_alt (loop, reduction_list, alt_bound);
return true;
}
else
{
/* Todo: Figure out if we can trigger this, if it's worth to handle
optimally, and if we can handle it optimally. */
return false;
}
}
gcc_assert (TREE_CODE (nit) == SSA_NAME);
/* Variable nit is the loop bound as returned by canonicalize_loop_ivs, for an
iv with base 0 and step 1 that is incremented in the latch, like this:
<bb header>:
# iv_1 = PHI <0 (preheader), iv_2 (latch)>
...
if (iv_1 < nit)
goto <bb latch>;
else
goto <bb exit>;
<bb latch>:
iv_2 = iv_1 + 1;
goto <bb header>;
The range of iv_1 is [0, nit]. The latch edge is taken for
iv_1 == [0, nit - 1] and the exit edge is taken for iv_1 == nit. So the
number of latch executions is equal to nit.
The function max_loop_iterations gives us the maximum number of latch
executions, so it gives us the maximum value of nit. */
widest_int nit_max;
if (!max_loop_iterations (loop, &nit_max))
return false;
/* Check if nit + 1 overflows. */
widest_int type_max = wi::to_widest (TYPE_MAX_VALUE (nit_type));
if (nit_max >= type_max)
return false;
gimple *def = SSA_NAME_DEF_STMT (nit);
/* Try to find nit + 1, in the form of n in an assignment nit = n - 1. */
if (def
&& is_gimple_assign (def)
&& gimple_assign_rhs_code (def) == PLUS_EXPR)
{
tree op1 = gimple_assign_rhs1 (def);
tree op2 = gimple_assign_rhs2 (def);
if (integer_minus_onep (op1))
alt_bound = op2;
else if (integer_minus_onep (op2))
alt_bound = op1;
}
/* If not found, insert nit + 1. */
if (alt_bound == NULL_TREE)
{
alt_bound = fold_build2 (PLUS_EXPR, nit_type, nit,
build_int_cst_type (nit_type, 1));
gimple_stmt_iterator gsi = gsi_last_bb (loop_preheader_edge (loop)->src);
alt_bound
= force_gimple_operand_gsi (&gsi, alt_bound, true, NULL_TREE, false,
GSI_CONTINUE_LINKING);
}
transform_to_exit_first_loop_alt (loop, reduction_list, alt_bound);
return true;
}
/* Moves the exit condition of LOOP to the beginning of its header. NIT is the
number of iterations of the loop. REDUCTION_LIST describes the reductions in
LOOP. */
static void
transform_to_exit_first_loop (class loop *loop,
reduction_info_table_type *reduction_list,
tree nit)
{
basic_block *bbs, *nbbs, ex_bb, orig_header;
unsigned n;
bool ok;
edge exit = single_dom_exit (loop), hpred;
tree control, control_name, res, t;
gphi *phi, *nphi;
gassign *stmt;
gcond *cond_stmt, *cond_nit;
tree nit_1;
split_block_after_labels (loop->header);
orig_header = single_succ (loop->header);
hpred = single_succ_edge (loop->header);
cond_stmt = as_a <gcond *> (last_stmt (exit->src));
control = gimple_cond_lhs (cond_stmt);
gcc_assert (gimple_cond_rhs (cond_stmt) == nit);
/* Make sure that we have phi nodes on exit for all loop header phis
(create_parallel_loop requires that). */
for (gphi_iterator gsi = gsi_start_phis (loop->header);
!gsi_end_p (gsi);
gsi_next (&gsi))
{
phi = gsi.phi ();
res = PHI_RESULT (phi);
t = copy_ssa_name (res, phi);
SET_PHI_RESULT (phi, t);
nphi = create_phi_node (res, orig_header);
add_phi_arg (nphi, t, hpred, UNKNOWN_LOCATION);
if (res == control)
{
gimple_cond_set_lhs (cond_stmt, t);
update_stmt (cond_stmt);
control = t;
}
}
bbs = get_loop_body_in_dom_order (loop);
for (n = 0; bbs[n] != exit->src; n++)
continue;
nbbs = XNEWVEC (basic_block, n);
ok = gimple_duplicate_sese_tail (single_succ_edge (loop->header), exit,
bbs + 1, n, nbbs);
gcc_assert (ok);
free (bbs);
ex_bb = nbbs[0];
free (nbbs);
/* Other than reductions, the only gimple reg that should be copied
out of the loop is the control variable. */
exit = single_dom_exit (loop);
control_name = NULL_TREE;
for (gphi_iterator gsi = gsi_start_phis (ex_bb);
!gsi_end_p (gsi); )
{
phi = gsi.phi ();
res = PHI_RESULT (phi);
if (virtual_operand_p (res))
{
gsi_next (&gsi);
continue;
}
/* Check if it is a part of reduction. If it is,
keep the phi at the reduction's keep_res field. The
PHI_RESULT of this phi is the resulting value of the reduction
variable when exiting the loop. */
if (!reduction_list->is_empty ())
{
struct reduction_info *red;
tree val = PHI_ARG_DEF_FROM_EDGE (phi, exit);
red = reduction_phi (reduction_list, SSA_NAME_DEF_STMT (val));
if (red)
{
red->keep_res = phi;
gsi_next (&gsi);
continue;
}
}
gcc_assert (control_name == NULL_TREE
&& SSA_NAME_VAR (res) == SSA_NAME_VAR (control));
control_name = res;
remove_phi_node (&gsi, false);
}
gcc_assert (control_name != NULL_TREE);
/* Initialize the control variable to number of iterations
according to the rhs of the exit condition. */
gimple_stmt_iterator gsi = gsi_after_labels (ex_bb);
cond_nit = as_a <gcond *> (last_stmt (exit->src));
nit_1 = gimple_cond_rhs (cond_nit);
nit_1 = force_gimple_operand_gsi (&gsi,
fold_convert (TREE_TYPE (control_name), nit_1),
false, NULL_TREE, false, GSI_SAME_STMT);
stmt = gimple_build_assign (control_name, nit_1);
gsi_insert_before (&gsi, stmt, GSI_NEW_STMT);
}
/* Create the parallel constructs for LOOP as described in gen_parallel_loop.
LOOP_FN and DATA are the arguments of GIMPLE_OMP_PARALLEL.
NEW_DATA is the variable that should be initialized from the argument
of LOOP_FN. N_THREADS is the requested number of threads, which can be 0 if
that number is to be determined later. */
static void
create_parallel_loop (class loop *loop, tree loop_fn, tree data,
tree new_data, unsigned n_threads, location_t loc,
bool oacc_kernels_p)
{
gimple_stmt_iterator gsi;
basic_block for_bb, ex_bb, continue_bb;
tree t, param;
gomp_parallel *omp_par_stmt;
gimple *omp_return_stmt1, *omp_return_stmt2;
gimple *phi;
gcond *cond_stmt;
gomp_for *for_stmt;
gomp_continue *omp_cont_stmt;
tree cvar, cvar_init, initvar, cvar_next, cvar_base, type;
edge exit, nexit, guard, end, e;
if (oacc_kernels_p)
{
gcc_checking_assert (lookup_attribute ("oacc kernels",
DECL_ATTRIBUTES (cfun->decl)));
/* Indicate to later processing that this is a parallelized OpenACC
kernels construct. */
DECL_ATTRIBUTES (cfun->decl)
= tree_cons (get_identifier ("oacc kernels parallelized"),
NULL_TREE, DECL_ATTRIBUTES (cfun->decl));
}
else
{
/* Prepare the GIMPLE_OMP_PARALLEL statement. */
basic_block bb = loop_preheader_edge (loop)->src;
basic_block paral_bb = single_pred (bb);
gsi = gsi_last_bb (paral_bb);
gcc_checking_assert (n_threads != 0);
t = build_omp_clause (loc, OMP_CLAUSE_NUM_THREADS);
OMP_CLAUSE_NUM_THREADS_EXPR (t)
= build_int_cst (integer_type_node, n_threads);
omp_par_stmt = gimple_build_omp_parallel (NULL, t, loop_fn, data);
gimple_set_location (omp_par_stmt, loc);
gsi_insert_after (&gsi, omp_par_stmt, GSI_NEW_STMT);
/* Initialize NEW_DATA. */
if (data)
{
gassign *assign_stmt;
gsi = gsi_after_labels (bb);
param = make_ssa_name (DECL_ARGUMENTS (loop_fn));
assign_stmt = gimple_build_assign (param, build_fold_addr_expr (data));
gsi_insert_before (&gsi, assign_stmt, GSI_SAME_STMT);
assign_stmt = gimple_build_assign (new_data,
fold_convert (TREE_TYPE (new_data), param));
gsi_insert_before (&gsi, assign_stmt, GSI_SAME_STMT);
}
/* Emit GIMPLE_OMP_RETURN for GIMPLE_OMP_PARALLEL. */
bb = split_loop_exit_edge (single_dom_exit (loop));
gsi = gsi_last_bb (bb);
omp_return_stmt1 = gimple_build_omp_return (false);
gimple_set_location (omp_return_stmt1, loc);
gsi_insert_after (&gsi, omp_return_stmt1, GSI_NEW_STMT);
}
/* Extract data for GIMPLE_OMP_FOR. */
gcc_assert (loop->header == single_dom_exit (loop)->src);
cond_stmt = as_a <gcond *> (last_stmt (loop->header));
cvar = gimple_cond_lhs (cond_stmt);
cvar_base = SSA_NAME_VAR (cvar);
phi = SSA_NAME_DEF_STMT (cvar);
cvar_init = PHI_ARG_DEF_FROM_EDGE (phi, loop_preheader_edge (loop));
initvar = copy_ssa_name (cvar);
SET_USE (PHI_ARG_DEF_PTR_FROM_EDGE (phi, loop_preheader_edge (loop)),
initvar);
cvar_next = PHI_ARG_DEF_FROM_EDGE (phi, loop_latch_edge (loop));
gsi = gsi_last_nondebug_bb (loop->latch);
gcc_assert (gsi_stmt (gsi) == SSA_NAME_DEF_STMT (cvar_next));
gsi_remove (&gsi, true);
/* Prepare cfg. */
for_bb = split_edge (loop_preheader_edge (loop));
ex_bb = split_loop_exit_edge (single_dom_exit (loop));
extract_true_false_edges_from_block (loop->header, &nexit, &exit);
gcc_assert (exit == single_dom_exit (loop));
guard = make_edge (for_bb, ex_bb, 0);
/* FIXME: What is the probability? */
guard->probability = profile_probability::guessed_never ();
/* Split the latch edge, so LOOPS_HAVE_SIMPLE_LATCHES is still valid. */
loop->latch = split_edge (single_succ_edge (loop->latch));
single_pred_edge (loop->latch)->flags = 0;
end = make_single_succ_edge (single_pred (loop->latch), ex_bb, EDGE_FALLTHRU);
rescan_loop_exit (end, true, false);
for (gphi_iterator gpi = gsi_start_phis (ex_bb);
!gsi_end_p (gpi); gsi_next (&gpi))
{
location_t locus;
gphi *phi = gpi.phi ();
tree def = PHI_ARG_DEF_FROM_EDGE (phi, exit);
gimple *def_stmt = SSA_NAME_DEF_STMT (def);
/* If the exit phi is not connected to a header phi in the same loop, this
value is not modified in the loop, and we're done with this phi. */
if (!(gimple_code (def_stmt) == GIMPLE_PHI
&& gimple_bb (def_stmt) == loop->header))
{
locus = gimple_phi_arg_location_from_edge (phi, exit);
add_phi_arg (phi, def, guard, locus);
add_phi_arg (phi, def, end, locus);
continue;
}
gphi *stmt = as_a <gphi *> (def_stmt);
def = PHI_ARG_DEF_FROM_EDGE (stmt, loop_preheader_edge (loop));
locus = gimple_phi_arg_location_from_edge (stmt,
loop_preheader_edge (loop));
add_phi_arg (phi, def, guard, locus);
def = PHI_ARG_DEF_FROM_EDGE (stmt, loop_latch_edge (loop));
locus = gimple_phi_arg_location_from_edge (stmt, loop_latch_edge (loop));
add_phi_arg (phi, def, end, locus);
}
e = redirect_edge_and_branch (exit, nexit->dest);
PENDING_STMT (e) = NULL;
/* Emit GIMPLE_OMP_FOR. */
if (oacc_kernels_p)
/* Parallelized OpenACC kernels constructs use gang parallelism. See also
omp-offload.c:execute_oacc_loop_designation. */
t = build_omp_clause (loc, OMP_CLAUSE_GANG);
else
{
t = build_omp_clause (loc, OMP_CLAUSE_SCHEDULE);
int chunk_size = param_parloops_chunk_size;
switch (param_parloops_schedule)
{
case PARLOOPS_SCHEDULE_STATIC:
OMP_CLAUSE_SCHEDULE_KIND (t) = OMP_CLAUSE_SCHEDULE_STATIC;
break;
case PARLOOPS_SCHEDULE_DYNAMIC:
OMP_CLAUSE_SCHEDULE_KIND (t) = OMP_CLAUSE_SCHEDULE_DYNAMIC;
break;
case PARLOOPS_SCHEDULE_GUIDED:
OMP_CLAUSE_SCHEDULE_KIND (t) = OMP_CLAUSE_SCHEDULE_GUIDED;
break;
case PARLOOPS_SCHEDULE_AUTO:
OMP_CLAUSE_SCHEDULE_KIND (t) = OMP_CLAUSE_SCHEDULE_AUTO;
chunk_size = 0;
break;
case PARLOOPS_SCHEDULE_RUNTIME:
OMP_CLAUSE_SCHEDULE_KIND (t) = OMP_CLAUSE_SCHEDULE_RUNTIME;
chunk_size = 0;
break;
default:
gcc_unreachable ();
}
if (chunk_size != 0)
OMP_CLAUSE_SCHEDULE_CHUNK_EXPR (t)
= build_int_cst (integer_type_node, chunk_size);
}
for_stmt = gimple_build_omp_for (NULL,
(oacc_kernels_p
? GF_OMP_FOR_KIND_OACC_LOOP
: GF_OMP_FOR_KIND_FOR),
t, 1, NULL);
gimple_cond_set_lhs (cond_stmt, cvar_base);
type = TREE_TYPE (cvar);
gimple_set_location (for_stmt, loc);
gimple_omp_for_set_index (for_stmt, 0, initvar);
gimple_omp_for_set_initial (for_stmt, 0, cvar_init);
gimple_omp_for_set_final (for_stmt, 0, gimple_cond_rhs (cond_stmt));
gimple_omp_for_set_cond (for_stmt, 0, gimple_cond_code (cond_stmt));
gimple_omp_for_set_incr (for_stmt, 0, build2 (PLUS_EXPR, type,
cvar_base,
build_int_cst (type, 1)));
gsi = gsi_last_bb (for_bb);
gsi_insert_after (&gsi, for_stmt, GSI_NEW_STMT);
SSA_NAME_DEF_STMT (initvar) = for_stmt;
/* Emit GIMPLE_OMP_CONTINUE. */