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/* Scheduler hooks for IA-32 which implement Core 2 specific logic.
Copyright (C) 1988-2025 Free Software Foundation, Inc.
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/>. */
#define IN_TARGET_CODE 1
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "backend.h"
#include "rtl.h"
#include "tree.h"
#include "cfghooks.h"
#include "tm_p.h"
#include "insn-config.h"
#include "insn-attr.h"
#include "recog.h"
#include "target.h"
#include "rtl-iter.h"
#include "regset.h"
#include "sched-int.h"
/* Model decoder of Core 2/i7.
Below hooks for multipass scheduling (see haifa-sched.cc:max_issue)
track the instruction fetch block boundaries and make sure that long
(9+ bytes) instructions are assigned to D0. */
/* Maximum length of an insn that can be handled by
a secondary decoder unit. '8' for Core 2/i7. */
static int core2i7_secondary_decoder_max_insn_size;
/* Ifetch block size, i.e., number of bytes decoder reads per cycle.
'16' for Core 2/i7. */
static int core2i7_ifetch_block_size;
/* Maximum number of instructions decoder can handle per cycle.
'6' for Core 2/i7. */
static int core2i7_ifetch_block_max_insns;
typedef struct ix86_first_cycle_multipass_data_ *
ix86_first_cycle_multipass_data_t;
typedef const struct ix86_first_cycle_multipass_data_ *
const_ix86_first_cycle_multipass_data_t;
/* A variable to store target state across calls to max_issue within
one cycle. */
static struct ix86_first_cycle_multipass_data_ _ix86_first_cycle_multipass_data,
*ix86_first_cycle_multipass_data = &_ix86_first_cycle_multipass_data;
/* Initialize DATA. */
static void
core2i7_first_cycle_multipass_init (void *_data)
{
ix86_first_cycle_multipass_data_t data
= (ix86_first_cycle_multipass_data_t) _data;
data->ifetch_block_len = 0;
data->ifetch_block_n_insns = 0;
data->ready_try_change = NULL;
data->ready_try_change_size = 0;
}
/* Advancing the cycle; reset ifetch block counts. */
static void
core2i7_dfa_post_advance_cycle (void)
{
ix86_first_cycle_multipass_data_t data = ix86_first_cycle_multipass_data;
gcc_assert (data->ifetch_block_n_insns <= core2i7_ifetch_block_max_insns);
data->ifetch_block_len = 0;
data->ifetch_block_n_insns = 0;
}
/* Filter out insns from ready_try that the core will not be able to issue
on current cycle due to decoder. */
static void
core2i7_first_cycle_multipass_filter_ready_try
(const_ix86_first_cycle_multipass_data_t data,
signed char *ready_try, int n_ready, bool first_cycle_insn_p)
{
while (n_ready--)
{
rtx_insn *insn;
int insn_size;
if (ready_try[n_ready])
continue;
insn = get_ready_element (n_ready);
insn_size = ix86_min_insn_size (insn);
if (/* If this is a too long an insn for a secondary decoder ... */
(!first_cycle_insn_p
&& insn_size > core2i7_secondary_decoder_max_insn_size)
/* ... or it would not fit into the ifetch block ... */
|| data->ifetch_block_len + insn_size > core2i7_ifetch_block_size
/* ... or the decoder is full already ... */
|| data->ifetch_block_n_insns + 1 > core2i7_ifetch_block_max_insns)
/* ... mask the insn out. */
{
ready_try[n_ready] = 1;
if (data->ready_try_change)
bitmap_set_bit (data->ready_try_change, n_ready);
}
}
}
/* Prepare for a new round of multipass lookahead scheduling. */
static void
core2i7_first_cycle_multipass_begin (void *_data,
signed char *ready_try, int n_ready,
bool first_cycle_insn_p)
{
ix86_first_cycle_multipass_data_t data
= (ix86_first_cycle_multipass_data_t) _data;
const_ix86_first_cycle_multipass_data_t prev_data
= ix86_first_cycle_multipass_data;
/* Restore the state from the end of the previous round. */
data->ifetch_block_len = prev_data->ifetch_block_len;
data->ifetch_block_n_insns = prev_data->ifetch_block_n_insns;
/* Filter instructions that cannot be issued on current cycle due to
decoder restrictions. */
core2i7_first_cycle_multipass_filter_ready_try (data, ready_try, n_ready,
first_cycle_insn_p);
}
/* INSN is being issued in current solution. Account for its impact on
the decoder model. */
static void
core2i7_first_cycle_multipass_issue (void *_data,
signed char *ready_try, int n_ready,
rtx_insn *insn, const void *_prev_data)
{
ix86_first_cycle_multipass_data_t data
= (ix86_first_cycle_multipass_data_t) _data;
const_ix86_first_cycle_multipass_data_t prev_data
= (const_ix86_first_cycle_multipass_data_t) _prev_data;
int insn_size = ix86_min_insn_size (insn);
data->ifetch_block_len = prev_data->ifetch_block_len + insn_size;
data->ifetch_block_n_insns = prev_data->ifetch_block_n_insns + 1;
gcc_assert (data->ifetch_block_len <= core2i7_ifetch_block_size
&& data->ifetch_block_n_insns <= core2i7_ifetch_block_max_insns);
/* Allocate or resize the bitmap for storing INSN's effect on ready_try. */
if (!data->ready_try_change)
{
data->ready_try_change = sbitmap_alloc (n_ready);
data->ready_try_change_size = n_ready;
}
else if (data->ready_try_change_size < n_ready)
{
data->ready_try_change = sbitmap_resize (data->ready_try_change,
n_ready, 0);
data->ready_try_change_size = n_ready;
}
bitmap_clear (data->ready_try_change);
/* Filter out insns from ready_try that the core will not be able to issue
on current cycle due to decoder. */
core2i7_first_cycle_multipass_filter_ready_try (data, ready_try, n_ready,
false);
}
/* Revert the effect on ready_try. */
static void
core2i7_first_cycle_multipass_backtrack (const void *_data,
signed char *ready_try,
int n_ready ATTRIBUTE_UNUSED)
{
const_ix86_first_cycle_multipass_data_t data
= (const_ix86_first_cycle_multipass_data_t) _data;
unsigned int i = 0;
sbitmap_iterator sbi;
gcc_assert (bitmap_last_set_bit (data->ready_try_change) < n_ready);
EXECUTE_IF_SET_IN_BITMAP (data->ready_try_change, 0, i, sbi)
{
ready_try[i] = 0;
}
}
/* Save the result of multipass lookahead scheduling for the next round. */
static void
core2i7_first_cycle_multipass_end (const void *_data)
{
const_ix86_first_cycle_multipass_data_t data
= (const_ix86_first_cycle_multipass_data_t) _data;
ix86_first_cycle_multipass_data_t next_data
= ix86_first_cycle_multipass_data;
if (data != NULL)
{
next_data->ifetch_block_len = data->ifetch_block_len;
next_data->ifetch_block_n_insns = data->ifetch_block_n_insns;
}
}
/* Deallocate target data. */
static void
core2i7_first_cycle_multipass_fini (void *_data)
{
ix86_first_cycle_multipass_data_t data
= (ix86_first_cycle_multipass_data_t) _data;
if (data->ready_try_change)
{
sbitmap_free (data->ready_try_change);
data->ready_try_change = NULL;
data->ready_try_change_size = 0;
}
}
void
ix86_core2i7_init_hooks (void)
{
targetm.sched.dfa_post_advance_cycle
= core2i7_dfa_post_advance_cycle;
targetm.sched.first_cycle_multipass_init
= core2i7_first_cycle_multipass_init;
targetm.sched.first_cycle_multipass_begin
= core2i7_first_cycle_multipass_begin;
targetm.sched.first_cycle_multipass_issue
= core2i7_first_cycle_multipass_issue;
targetm.sched.first_cycle_multipass_backtrack
= core2i7_first_cycle_multipass_backtrack;
targetm.sched.first_cycle_multipass_end
= core2i7_first_cycle_multipass_end;
targetm.sched.first_cycle_multipass_fini
= core2i7_first_cycle_multipass_fini;
/* Set decoder parameters. */
core2i7_secondary_decoder_max_insn_size = 8;
core2i7_ifetch_block_size = 16;
core2i7_ifetch_block_max_insns = 6;
}
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