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/* Gimple range edge functionality.
Copyright (C) 2020-2024 Free Software Foundation, Inc.
Contributed by Andrew MacLeod <amacleod@redhat.com>
and Aldy Hernandez <aldyh@redhat.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 "ssa.h"
#include "gimple-pretty-print.h"
#include "gimple-iterator.h"
#include "tree-cfg.h"
#include "gimple-range.h"
#include "value-range-storage.h"
// If there is a range control statement at the end of block BB, return it.
// Otherwise return NULL.
gimple *
gimple_outgoing_range_stmt_p (basic_block bb)
{
gimple_stmt_iterator gsi = gsi_last_nondebug_bb (bb);
if (!gsi_end_p (gsi))
{
gimple *s = gsi_stmt (gsi);
if (is_a<gcond *> (s) && gimple_range_op_handler::supported_p (s))
return gsi_stmt (gsi);
if (is_a <gswitch *> (s))
return gsi_stmt (gsi);
}
return NULL;
}
// Return a TRUE or FALSE range representing the edge value of a GCOND.
void
gcond_edge_range (irange &r, edge e)
{
gcc_checking_assert (e->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE));
if (e->flags & EDGE_TRUE_VALUE)
r = range_true ();
else
r = range_false ();
}
// Construct a gimple_outgoing_range object. No memory is allocated.
gimple_outgoing_range::gimple_outgoing_range (int max_sw_edges)
{
m_edge_table = NULL;
m_range_allocator = NULL;
m_max_edges = max_sw_edges;
}
// Destruct an edge object, disposing of any memory allocated.
gimple_outgoing_range::~gimple_outgoing_range ()
{
if (m_edge_table)
delete m_edge_table;
if (m_range_allocator)
delete m_range_allocator;
}
// Set a new switch limit.
void
gimple_outgoing_range::set_switch_limit (int max_sw_edges)
{
m_max_edges = max_sw_edges;
}
// Get a range for a switch edge E from statement S and return it in R.
// Use a cached value if it exists, or calculate it if not.
bool
gimple_outgoing_range::switch_edge_range (irange &r, gswitch *sw, edge e)
{
// ADA currently has cases where the index is 64 bits and the case
// arguments are 32 bit, causing a trap when we create a case_range.
// Until this is resolved (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87798)
// punt on switches where the labels don't match the argument.
if (gimple_switch_num_labels (sw) > 1 &&
TYPE_PRECISION (TREE_TYPE (CASE_LOW (gimple_switch_label (sw, 1)))) !=
TYPE_PRECISION (TREE_TYPE (gimple_switch_index (sw))))
return false;
if (!m_edge_table)
m_edge_table = new hash_map<edge, vrange_storage *> (n_edges_for_fn (cfun));
if (!m_range_allocator)
m_range_allocator = new vrange_allocator;
vrange_storage **val = m_edge_table->get (e);
if (!val)
{
calc_switch_ranges (sw);
val = m_edge_table->get (e);
gcc_checking_assert (val);
}
(*val)->get_vrange (r, TREE_TYPE (gimple_switch_index (sw)));
return true;
}
// Calculate all switch edges from SW and cache them in the hash table.
void
gimple_outgoing_range::calc_switch_ranges (gswitch *sw)
{
bool existed;
unsigned x, lim;
lim = gimple_switch_num_labels (sw);
tree type = TREE_TYPE (gimple_switch_index (sw));
edge default_edge = gimple_switch_default_edge (cfun, sw);
// This should be the first call into this switch.
//
// Allocate an int_range_max for the default range case, start with
// varying and intersect each other case from it.
int_range_max default_range (type);
for (x = 1; x < lim; x++)
{
edge e = gimple_switch_edge (cfun, sw, x);
// If this edge is the same as the default edge, do nothing else.
if (e == default_edge)
continue;
wide_int low = wi::to_wide (CASE_LOW (gimple_switch_label (sw, x)));
wide_int high;
tree tree_high = CASE_HIGH (gimple_switch_label (sw, x));
if (tree_high)
high = wi::to_wide (tree_high);
else
high = low;
// Remove the case range from the default case.
int_range_max def_range (type, low, high);
range_cast (def_range, type);
def_range.invert ();
default_range.intersect (def_range);
// Create/union this case with anything on else on the edge.
int_range_max case_range (type, low, high);
range_cast (case_range, type);
vrange_storage *&slot = m_edge_table->get_or_insert (e, &existed);
if (existed)
{
// If this doesn't change the value, move on.
int_range_max tmp;
slot->get_vrange (tmp, type);
if (!case_range.union_ (tmp))
continue;
if (slot->fits_p (case_range))
{
slot->set_vrange (case_range);
continue;
}
}
// If there was an existing range and it doesn't fit, we lose the memory.
// It'll get reclaimed when the obstack is freed. This seems less
// intrusive than allocating max ranges for each case.
slot = m_range_allocator->clone (case_range);
}
vrange_storage *&slot = m_edge_table->get_or_insert (default_edge, &existed);
// This should be the first call into this switch.
gcc_checking_assert (!existed);
slot = m_range_allocator->clone (default_range);
}
// Calculate the range forced on on edge E by control flow, return it
// in R. Return the statement which defines the range, otherwise
// return NULL
gimple *
gimple_outgoing_range::edge_range_p (irange &r, edge e)
{
if (single_succ_p (e->src))
return NULL;
// Determine if there is an outgoing edge.
gimple *s = gimple_outgoing_range_stmt_p (e->src);
if (!s)
return NULL;
if (is_a<gcond *> (s))
{
gcond_edge_range (r, e);
return s;
}
// Only process switches if it within the size limit.
if (m_max_edges == 0 || (EDGE_COUNT (e->src->succs) > (unsigned)m_max_edges))
return NULL;
gcc_checking_assert (is_a<gswitch *> (s));
gswitch *sw = as_a<gswitch *> (s);
// Switches can only be integers.
if (switch_edge_range (as_a <irange> (r), sw, e))
return s;
return NULL;
}
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