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/* The fp-as-gp pass of Andes NDS32 cpu for GNU compiler
Copyright (C) 2012-2014 Free Software Foundation, Inc.
Contributed by Andes Technology Corporation.
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 "stor-layout.h"
#include "varasm.h"
#include "calls.h"
#include "rtl.h"
#include "regs.h"
#include "hard-reg-set.h"
#include "insn-config.h" /* Required by recog.h. */
#include "conditions.h"
#include "output.h"
#include "insn-attr.h" /* For DFA state_t. */
#include "insn-codes.h" /* For CODE_FOR_xxx. */
#include "reload.h" /* For push_reload(). */
#include "flags.h"
#include "hashtab.h"
#include "hash-set.h"
#include "vec.h"
#include "machmode.h"
#include "input.h"
#include "function.h"
#include "expr.h"
#include "recog.h"
#include "diagnostic-core.h"
#include "dominance.h"
#include "cfg.h"
#include "cfgrtl.h"
#include "cfganal.h"
#include "lcm.h"
#include "cfgbuild.h"
#include "cfgcleanup.h"
#include "predict.h"
#include "basic-block.h"
#include "df.h"
#include "tm_p.h"
#include "tm-constrs.h"
#include "optabs.h" /* For GEN_FCN. */
#include "target.h"
#include "target-def.h"
#include "langhooks.h" /* For add_builtin_function(). */
#include "ggc.h"
#include "builtins.h"
/* ------------------------------------------------------------------------ */
/* A helper function to check if this function should contain prologue. */
static int
nds32_have_prologue_p (void)
{
int i;
for (i = 0; i < 28; i++)
if (NDS32_REQUIRED_CALLEE_SAVED_P (i))
return 1;
return (flag_pic
|| NDS32_REQUIRED_CALLEE_SAVED_P (FP_REGNUM)
|| NDS32_REQUIRED_CALLEE_SAVED_P (LP_REGNUM));
}
/* Return true if is load/store with SYMBOL_REF addressing mode
and memory mode is SImode. */
static bool
nds32_symbol_load_store_p (rtx_insn *insn)
{
rtx mem_src = NULL_RTX;
switch (get_attr_type (insn))
{
case TYPE_LOAD:
mem_src = SET_SRC (PATTERN (insn));
break;
case TYPE_STORE:
mem_src = SET_DEST (PATTERN (insn));
break;
default:
break;
}
/* Find load/store insn with addressing mode is SYMBOL_REF. */
if (mem_src != NULL_RTX)
{
if ((GET_CODE (mem_src) == ZERO_EXTEND)
|| (GET_CODE (mem_src) == SIGN_EXTEND))
mem_src = XEXP (mem_src, 0);
if ((GET_CODE (XEXP (mem_src, 0)) == SYMBOL_REF)
|| (GET_CODE (XEXP (mem_src, 0)) == LO_SUM))
return true;
}
return false;
}
/* Function to determine whether it is worth to do fp_as_gp optimization.
Return 0: It is NOT worth to do fp_as_gp optimization.
Return 1: It is APPROXIMATELY worth to do fp_as_gp optimization.
Note that if it is worth to do fp_as_gp optimization,
we MUST set FP_REGNUM ever live in this function. */
int
nds32_fp_as_gp_check_available (void)
{
/* If there exists ANY of following conditions,
we DO NOT perform fp_as_gp optimization:
1. TARGET_FORBID_FP_AS_GP is set
regardless of the TARGET_FORCE_FP_AS_GP.
2. User explicitly uses 'naked' attribute.
3. Not optimize for size.
4. Need frame pointer.
5. If $fp is already required to be saved,
it means $fp is already choosen by register allocator.
Thus we better not to use it for fp_as_gp optimization.
6. This function is a vararg function.
DO NOT apply fp_as_gp optimization on this function
because it may change and break stack frame.
7. The epilogue is empty.
This happens when the function uses exit()
or its attribute is no_return.
In that case, compiler will not expand epilogue
so that we have no chance to output .omit_fp_end directive. */
if (TARGET_FORBID_FP_AS_GP
|| lookup_attribute ("naked", DECL_ATTRIBUTES (current_function_decl))
|| !optimize_size
|| frame_pointer_needed
|| NDS32_REQUIRED_CALLEE_SAVED_P (FP_REGNUM)
|| (cfun->stdarg == 1)
|| (find_fallthru_edge (EXIT_BLOCK_PTR_FOR_FN (cfun)->preds) == NULL))
return 0;
/* Now we can check the possibility of using fp_as_gp optimization. */
if (TARGET_FORCE_FP_AS_GP)
{
/* User explicitly issues -mforce-fp-as-gp option. */
df_set_regs_ever_live (FP_REGNUM, 1);
return 1;
}
else
{
/* In the following we are going to evaluate whether
it is worth to do fp_as_gp optimization. */
int good_gain = 0;
int symbol_count = 0;
int threshold;
rtx_insn *insn;
/* We check if there already requires prologue.
Note that $gp will be saved in prologue for PIC code generation.
After that, we can set threshold by the existence of prologue.
Each fp-implied instruction will gain 2-byte code size
from gp-aware instruction, so we have following heuristics. */
if (flag_pic
|| nds32_have_prologue_p ())
{
/* Have-prologue:
Compiler already intends to generate prologue content,
so the fp_as_gp optimization will only insert
'la $fp,_FP_BASE_' instruction, which will be
converted into 4-byte instruction at link time.
The threshold is "3" symbol accesses, 2 + 2 + 2 > 4. */
threshold = 3;
}
else
{
/* None-prologue:
Compiler originally does not generate prologue content,
so the fp_as_gp optimization will NOT ONLY insert
'la $fp,_FP_BASE' instruction, but also causes
push/pop instructions.
If we are using v3push (push25/pop25),
the threshold is "5" symbol accesses, 5*2 > 4 + 2 + 2;
If we are using normal push (smw/lmw),
the threshold is "5+2" symbol accesses 7*2 > 4 + 4 + 4. */
threshold = 5 + (TARGET_V3PUSH ? 0 : 2);
}
/* We would like to traverse every instruction in this function.
So we need to have push_topmost_sequence()/pop_topmost_sequence()
surrounding our for-loop evaluation. */
push_topmost_sequence ();
/* Counting the insn number which the addressing mode is symbol. */
for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
{
if (single_set (insn) && nds32_symbol_load_store_p (insn))
symbol_count++;
if (symbol_count == threshold)
{
good_gain = 1;
break;
}
}
pop_topmost_sequence ();
/* Enable fp_as_gp optimization when potential gain is good enough. */
if (good_gain)
{
df_set_regs_ever_live (FP_REGNUM, 1);
return 1;
}
}
/* By default we return 0. */
return 0;
}
/* ------------------------------------------------------------------------ */
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