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Remove reduction chain detection from parloops

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Historically SLP reduction chains were the only multi-stmt reductions
supported.  But since we have check_reduction_path more complicated
cases are handled.  As parloops doesn't do any specific chain
processing it can solely rely on that functionality instead.

	* tree-parloops.cc (parloops_is_slp_reduction): Remove.
	(parloops_is_simple_reduction): Do not call it.
This commit is contained in:
Richard Biener
2025-08-19 13:38:58 +02:00
committed by Richard Biener
parent 3bc63918ce
commit f647d4f58a
1 changed files with 0 additions and 177 deletions
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177
gcc/tree-parloops.cc
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@@ -205,170 +205,6 @@ parloops_valid_reduction_input_p (stmt_vec_info def_stmt_info)
&& !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", (gimple *) 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. */
@@ -836,19 +672,6 @@ parloops_is_simple_reduction (loop_vec_info loop_info, stmt_vec_info phi_info,
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;