112 lines
3.5 KiB
C
112 lines
3.5 KiB
C
/* Discover if the stack pointer is modified in a function.
|
|
Copyright (C) 2007, 2008, 2009
|
|
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/>. */
|
|
|
|
#include "config.h"
|
|
#include "system.h"
|
|
#include "coretypes.h"
|
|
#include "tm.h"
|
|
#include "tree.h"
|
|
#include "rtl.h"
|
|
#include "regs.h"
|
|
#include "expr.h"
|
|
#include "tree-pass.h"
|
|
#include "basic-block.h"
|
|
#include "flags.h"
|
|
#include "output.h"
|
|
#include "df.h"
|
|
|
|
/* Determine if the stack pointer is constant over the life of the function.
|
|
Only useful before prologues have been emitted. */
|
|
|
|
static void
|
|
notice_stack_pointer_modification_1 (rtx x, const_rtx pat ATTRIBUTE_UNUSED,
|
|
void *data ATTRIBUTE_UNUSED)
|
|
{
|
|
if (x == stack_pointer_rtx
|
|
/* The stack pointer is only modified indirectly as the result
|
|
of a push until later. See the comments in rtl.texi
|
|
regarding Embedded Side-Effects on Addresses. */
|
|
|| (MEM_P (x)
|
|
&& GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == RTX_AUTOINC
|
|
&& XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
|
|
current_function_sp_is_unchanging = 0;
|
|
}
|
|
|
|
static void
|
|
notice_stack_pointer_modification (void)
|
|
{
|
|
basic_block bb;
|
|
rtx insn;
|
|
|
|
/* Assume that the stack pointer is unchanging if alloca hasn't
|
|
been used. */
|
|
current_function_sp_is_unchanging = !cfun->calls_alloca;
|
|
if (current_function_sp_is_unchanging)
|
|
FOR_EACH_BB (bb)
|
|
FOR_BB_INSNS (bb, insn)
|
|
{
|
|
if (INSN_P (insn))
|
|
{
|
|
/* Check if insn modifies the stack pointer. */
|
|
note_stores (PATTERN (insn),
|
|
notice_stack_pointer_modification_1,
|
|
NULL);
|
|
if (! current_function_sp_is_unchanging)
|
|
return;
|
|
}
|
|
}
|
|
|
|
/* The value coming into this pass was 0, and the exit block uses
|
|
are based on this. If the value is now 1, we need to redo the
|
|
exit block uses. */
|
|
if (df && current_function_sp_is_unchanging)
|
|
df_update_exit_block_uses ();
|
|
}
|
|
|
|
/* Some targets can emit simpler epilogues if they know that sp was
|
|
not ever modified during the function. After reload, of course,
|
|
we've already emitted the epilogue so there's no sense searching. */
|
|
|
|
static unsigned int
|
|
rest_of_handle_stack_ptr_mod (void)
|
|
{
|
|
notice_stack_pointer_modification ();
|
|
return 0;
|
|
}
|
|
|
|
struct rtl_opt_pass pass_stack_ptr_mod =
|
|
{
|
|
{
|
|
RTL_PASS,
|
|
"*stack_ptr_mod", /* name */
|
|
NULL, /* gate */
|
|
rest_of_handle_stack_ptr_mod, /* execute */
|
|
NULL, /* sub */
|
|
NULL, /* next */
|
|
0, /* static_pass_number */
|
|
TV_NONE, /* tv_id */
|
|
0, /* properties_required */
|
|
0, /* properties_provided */
|
|
0, /* properties_destroyed */
|
|
0, /* todo_flags_start */
|
|
0 /* todo_flags_finish */
|
|
}
|
|
};
|