/* Global constant/copy propagation for RTL.
- Copyright (C) 1997-2014 Free Software Foundation, Inc.
+ Copyright (C) 1997-2020 Free Software Foundation, Inc.
This file is part of GCC.
#include "config.h"
#include "system.h"
#include "coretypes.h"
-#include "tm.h"
-#include "diagnostic-core.h"
-#include "toplev.h"
-
+#include "backend.h"
#include "rtl.h"
-#include "tree.h"
-#include "tm_p.h"
-#include "regs.h"
-#include "hard-reg-set.h"
-#include "flags.h"
+#include "cfghooks.h"
+#include "df.h"
#include "insn-config.h"
+#include "memmodel.h"
+#include "emit-rtl.h"
#include "recog.h"
-#include "predict.h"
-#include "vec.h"
-#include "hashtab.h"
-#include "hash-set.h"
-#include "machmode.h"
-#include "input.h"
-#include "function.h"
-#include "dominance.h"
-#include "cfg.h"
+#include "diagnostic-core.h"
+#include "toplev.h"
#include "cfgrtl.h"
#include "cfganal.h"
#include "lcm.h"
#include "cfgcleanup.h"
-#include "basic-block.h"
-#include "expr.h"
-#include "except.h"
-#include "params.h"
#include "cselib.h"
#include "intl.h"
-#include "obstack.h"
#include "tree-pass.h"
-#include "df.h"
#include "dbgcnt.h"
-#include "target.h"
#include "cfgloop.h"
+#include "gcse.h"
\f
/* An obstack for our working variables. */
rtx_insn *insn;
};
-typedef struct cprop_occr *occr_t;
-
/* Hash table entry for assignment expressions. */
struct cprop_expr
return CONSTANT_P (x) && (GET_CODE (x) != CONST || shared_const_p (x));
}
+/* Determine whether the rtx X should be treated as a register that can
+ be propagated. Any pseudo-register is fine. */
+
+static bool
+cprop_reg_p (const_rtx x)
+{
+ return REG_P (x) && !HARD_REGISTER_P (x);
+}
+
/* Scan SET present in INSN and add an entry to the hash TABLE.
IMPLICIT is true if it's an implicit set, false otherwise. */
rtx src = SET_SRC (set);
rtx dest = SET_DEST (set);
- if (REG_P (dest)
- && ! HARD_REGISTER_P (dest)
+ if (cprop_reg_p (dest)
&& reg_available_p (dest, insn)
&& can_copy_p (GET_MODE (dest)))
{
&& REG_NOTE_KIND (note) == REG_EQUAL
&& !REG_P (src)
&& cprop_constant_p (XEXP (note, 0)))
- src = XEXP (note, 0), set = gen_rtx_SET (VOIDmode, dest, src);
+ src = XEXP (note, 0), set = gen_rtx_SET (dest, src);
/* Record sets for constant/copy propagation. */
- if ((REG_P (src)
+ if ((cprop_reg_p (src)
&& src != dest
- && ! HARD_REGISTER_P (src)
&& reg_available_p (src, insn))
|| cprop_constant_p (src))
insert_set_in_table (dest, src, insn, table, implicit);
int success = 0;
rtx set = single_set (insn);
+ bool check_rtx_costs = true;
+ bool speed = optimize_bb_for_speed_p (BLOCK_FOR_INSN (insn));
+ int old_cost = set ? set_rtx_cost (set, speed) : 0;
+
+ if (!set
+ || CONSTANT_P (SET_SRC (set))
+ || (note != 0
+ && REG_NOTE_KIND (note) == REG_EQUAL
+ && (GET_CODE (XEXP (note, 0)) == CONST
+ || CONSTANT_P (XEXP (note, 0)))))
+ check_rtx_costs = false;
+
/* Usually we substitute easy stuff, so we won't copy everything.
We however need to take care to not duplicate non-trivial CONST
expressions. */
to = copy_rtx (to);
validate_replace_src_group (from, to, insn);
+
+ /* If TO is a constant, check the cost of the set after propagation
+ to the cost of the set before the propagation. If the cost is
+ higher, then do not replace FROM with TO. */
+
+ if (check_rtx_costs
+ && CONSTANT_P (to)
+ && set_rtx_cost (set, speed) > old_cost)
+ {
+ cancel_changes (0);
+ return false;
+ }
+
+
if (num_changes_pending () && apply_change_group ())
success = 1;
return success;
}
-/* Find a set of REGNOs that are available on entry to INSN's block. Return
- NULL no such set is found. */
+/* Find a set of REGNOs that are available on entry to INSN's block. If found,
+ SET_RET[0] will be assigned a set with a register source and SET_RET[1] a
+ set with a constant source. If not found the corresponding entry is set to
+ NULL. */
-static struct cprop_expr *
-find_avail_set (int regno, rtx_insn *insn)
+static void
+find_avail_set (int regno, rtx_insn *insn, struct cprop_expr *set_ret[2])
{
- /* SET1 contains the last set found that can be returned to the caller for
- use in a substitution. */
- struct cprop_expr *set1 = 0;
+ set_ret[0] = set_ret[1] = NULL;
/* Loops are not possible here. To get a loop we would need two sets
available at the start of the block containing INSN. i.e. we would
(set (reg X) (reg Y))
(set (reg Y) (reg X))
- This can not happen since the set of (reg Y) would have killed the
+ This cannot happen since the set of (reg Y) would have killed the
set of (reg X) making it unavailable at the start of this block. */
while (1)
{
If the source operand changed, we may still use it for the next
iteration of this loop, but we may not use it for substitutions. */
- if (cprop_constant_p (src) || reg_not_set_p (src, insn))
- set1 = set;
+ if (cprop_constant_p (src))
+ set_ret[1] = set;
+ else if (reg_not_set_p (src, insn))
+ set_ret[0] = set;
/* If the source of the set is anything except a register, then
we have reached the end of the copy chain. */
and see if we have an available copy into SRC. */
regno = REGNO (src);
}
-
- /* SET1 holds the last set that was available and anticipatable at
- INSN. */
- return set1;
}
/* Subroutine of cprop_insn that tries to propagate constants into
remove_note (jump, note);
}
-#ifdef HAVE_cc0
/* Delete the cc0 setter. */
- if (setcc != NULL && CC0_P (SET_DEST (single_set (setcc))))
+ if (HAVE_cc0 && setcc != NULL && CC0_P (SET_DEST (single_set (setcc))))
delete_insn (setcc);
-#endif
global_const_prop_count++;
if (dump_file != NULL)
{
fprintf (dump_file,
- "GLOBAL CONST-PROP: Replacing reg %d in jump_insn %d with"
+ "GLOBAL CONST-PROP: Replacing reg %d in jump_insn %d with "
"constant ", REGNO (from), INSN_UID (jump));
print_rtl (dump_file, src);
fprintf (dump_file, "\n");
int changed = 0, changed_this_round;
rtx note;
-retry:
- changed_this_round = 0;
- reg_use_count = 0;
- note_uses (&PATTERN (insn), find_used_regs, NULL);
-
- /* We may win even when propagating constants into notes. */
- note = find_reg_equal_equiv_note (insn);
- if (note)
- find_used_regs (&XEXP (note, 0), NULL);
-
- for (i = 0; i < reg_use_count; i++)
+ do
{
- rtx reg_used = reg_use_table[i];
- unsigned int regno = REGNO (reg_used);
- rtx src;
- struct cprop_expr *set;
+ changed_this_round = 0;
+ reg_use_count = 0;
+ note_uses (&PATTERN (insn), find_used_regs, NULL);
- /* If the register has already been set in this block, there's
- nothing we can do. */
- if (! reg_not_set_p (reg_used, insn))
- continue;
+ /* We may win even when propagating constants into notes. */
+ note = find_reg_equal_equiv_note (insn);
+ if (note)
+ find_used_regs (&XEXP (note, 0), NULL);
- /* Find an assignment that sets reg_used and is available
- at the start of the block. */
- set = find_avail_set (regno, insn);
- if (! set)
- continue;
+ for (i = 0; i < reg_use_count; i++)
+ {
+ rtx reg_used = reg_use_table[i];
+ unsigned int regno = REGNO (reg_used);
+ rtx src_cst = NULL, src_reg = NULL;
+ struct cprop_expr *set[2];
- src = set->src;
+ /* If the register has already been set in this block, there's
+ nothing we can do. */
+ if (! reg_not_set_p (reg_used, insn))
+ continue;
- /* Constant propagation. */
- if (cprop_constant_p (src))
- {
- if (constprop_register (reg_used, src, insn))
+ /* Find an assignment that sets reg_used and is available
+ at the start of the block. */
+ find_avail_set (regno, insn, set);
+ if (set[0])
+ src_reg = set[0]->src;
+ if (set[1])
+ src_cst = set[1]->src;
+
+ /* Constant propagation. */
+ if (src_cst && cprop_constant_p (src_cst)
+ && constprop_register (reg_used, src_cst, insn))
{
changed_this_round = changed = 1;
global_const_prop_count++;
"GLOBAL CONST-PROP: Replacing reg %d in ", regno);
fprintf (dump_file, "insn %d with constant ",
INSN_UID (insn));
- print_rtl (dump_file, src);
+ print_rtl (dump_file, src_cst);
fprintf (dump_file, "\n");
}
if (insn->deleted ())
return 1;
}
- }
- else if (REG_P (src)
- && REGNO (src) >= FIRST_PSEUDO_REGISTER
- && REGNO (src) != regno)
- {
- if (try_replace_reg (reg_used, src, insn))
+ /* Copy propagation. */
+ else if (src_reg && cprop_reg_p (src_reg)
+ && REGNO (src_reg) != regno
+ && try_replace_reg (reg_used, src_reg, insn))
{
changed_this_round = changed = 1;
global_copy_prop_count++;
fprintf (dump_file,
"GLOBAL COPY-PROP: Replacing reg %d in insn %d",
regno, INSN_UID (insn));
- fprintf (dump_file, " with reg %d\n", REGNO (src));
+ fprintf (dump_file, " with reg %d\n", REGNO (src_reg));
}
/* The original insn setting reg_used may or may not now be
and made things worse. */
}
}
-
- /* If try_replace_reg simplified the insn, the regs found
- by find_used_regs may not be valid anymore. Start over. */
- if (changed_this_round)
- goto retry;
}
+ /* If try_replace_reg simplified the insn, the regs found by find_used_regs
+ may not be valid anymore. Start over. */
+ while (changed_this_round);
if (changed && DEBUG_INSN_P (insn))
return 0;
return;
case SUBREG:
- /* Setting a subreg of a register larger than word_mode leaves
- the non-written words unchanged. */
- if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) > BITS_PER_WORD)
+ if (read_modify_subreg_p (x))
return;
break;
/* Rule out USE instructions and ASM statements as we don't want to
change the hard registers mentioned. */
if (REG_P (x)
- && (REGNO (x) >= FIRST_PSEUDO_REGISTER
+ && (cprop_reg_p (x)
|| (GET_CODE (PATTERN (insn)) != USE
&& asm_noperands (PATTERN (insn)) < 0)))
{
if (cprop_constant_p (this_rtx))
newcnst = this_rtx;
- if (REG_P (this_rtx) && REGNO (this_rtx) >= FIRST_PSEUDO_REGISTER
+ if (cprop_reg_p (this_rtx)
/* Don't copy propagate if it has attached REG_EQUIV note.
At this point this only function parameters should have
REG_EQUIV notes and if the argument slot is used somewhere
bool changed = false;
unsigned i;
+ auto_vec<rtx_insn *> uncond_traps;
+
cselib_init (0);
FOR_EACH_BB_FN (bb, cfun)
{
{
if (INSN_P (insn))
{
+ bool was_uncond_trap
+ = (GET_CODE (PATTERN (insn)) == TRAP_IF
+ && XEXP (PATTERN (insn), 0) == const1_rtx);
rtx note = find_reg_equal_equiv_note (insn);
do
{
break;
}
}
+ if (!was_uncond_trap
+ && GET_CODE (PATTERN (insn)) == TRAP_IF
+ && XEXP (PATTERN (insn), 0) == const1_rtx)
+ {
+ uncond_traps.safe_push (insn);
+ break;
+ }
if (insn->deleted ())
break;
}
cselib_finish ();
+ while (!uncond_traps.is_empty ())
+ {
+ rtx_insn *insn = uncond_traps.pop ();
+ basic_block to_split = BLOCK_FOR_INSN (insn);
+ remove_edge (split_block (to_split, insn));
+ emit_barrier_after_bb (to_split);
+ }
+
return changed;
}
static bool
implicit_set_cond_p (const_rtx cond)
{
- enum machine_mode mode;
+ machine_mode mode;
rtx cst;
/* COND must be either an EQ or NE comparison. */
if (GET_CODE (cond) != EQ && GET_CODE (cond) != NE)
return false;
- /* The first operand of COND must be a pseudo-reg. */
- if (! REG_P (XEXP (cond, 0))
- || HARD_REGISTER_P (XEXP (cond, 0)))
+ /* The first operand of COND must be a register we can propagate. */
+ if (!cprop_reg_p (XEXP (cond, 0)))
return false;
/* The second operand of COND must be a suitable constant. */
the optimization can't be performed. */
/* ??? The complex and vector checks are not implemented yet. We just
always return zero for them. */
- if (CONST_DOUBLE_AS_FLOAT_P (cst))
- {
- REAL_VALUE_TYPE d;
- REAL_VALUE_FROM_CONST_DOUBLE (d, cst);
- if (REAL_VALUES_EQUAL (d, dconst0))
- return 0;
- }
+ if (CONST_DOUBLE_AS_FLOAT_P (cst)
+ && real_equal (CONST_DOUBLE_REAL_VALUE (cst), &dconst0))
+ return 0;
else
return 0;
}
(implicit_sets_size - old_implicit_sets_size) * sizeof (rtx));
}
- new_rtx = gen_rtx_SET (VOIDmode, XEXP (cond, 0),
- XEXP (cond, 1));
+ new_rtx = gen_rtx_SET (XEXP (cond, 0), XEXP (cond, 1));
implicit_sets[dest->index] = new_rtx;
if (dump_file)
{
if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb == EXIT_BLOCK_PTR_FOR_FN (cfun))
return 0;
- bypass_last_basic_block = last_basic_block_for_fn (cfun);
mark_dfs_back_edges ();
changed = 0;
return changed;
}
\f
-/* Return true if the graph is too expensive to optimize. PASS is the
- optimization about to be performed. */
-
-static bool
-is_too_expensive (const char *pass)
-{
- /* Trying to perform global optimizations on flow graphs which have
- a high connectivity will take a long time and is unlikely to be
- particularly useful.
-
- In normal circumstances a cfg should have about twice as many
- edges as blocks. But we do not want to punish small functions
- which have a couple switch statements. Rather than simply
- threshold the number of blocks, uses something with a more
- graceful degradation. */
- if (n_edges_for_fn (cfun) > 20000 + n_basic_blocks_for_fn (cfun) * 4)
- {
- warning (OPT_Wdisabled_optimization,
- "%s: %d basic blocks and %d edges/basic block",
- pass, n_basic_blocks_for_fn (cfun),
- n_edges_for_fn (cfun) / n_basic_blocks_for_fn (cfun));
-
- return true;
- }
-
- /* If allocating memory for the cprop bitmap would take up too much
- storage it's better just to disable the optimization. */
- if ((n_basic_blocks_for_fn (cfun)
- * SBITMAP_SET_SIZE (max_reg_num ())
- * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
- {
- warning (OPT_Wdisabled_optimization,
- "%s: %d basic blocks and %d registers",
- pass, n_basic_blocks_for_fn (cfun), max_reg_num ());
-
- return true;
- }
-
- return false;
-}
-\f
/* Main function for the CPROP pass. */
static int
/* Return if there's nothing to do, or it is too expensive. */
if (n_basic_blocks_for_fn (cfun) <= NUM_FIXED_BLOCKS + 1
- || is_too_expensive (_ ("const/copy propagation disabled")))
+ || gcse_or_cprop_is_too_expensive (_ ("const/copy propagation disabled")))
return 0;
global_const_prop_count = local_const_prop_count = 0;
if (set_hash_table.n_elems > 0)
{
basic_block bb;
- rtx_insn *insn;
+ auto_vec<rtx_insn *> uncond_traps;
alloc_cprop_mem (last_basic_block_for_fn (cfun),
set_hash_table.n_elems);
EXIT_BLOCK_PTR_FOR_FN (cfun),
next_bb)
{
+ bool seen_uncond_trap = false;
+ rtx_insn *insn;
+
/* Reset tables used to keep track of what's still valid [since
the start of the block]. */
reset_opr_set_tables ();
FOR_BB_INSNS (bb, insn)
if (INSN_P (insn))
{
+ bool was_uncond_trap
+ = (GET_CODE (PATTERN (insn)) == TRAP_IF
+ && XEXP (PATTERN (insn), 0) == const1_rtx);
+
changed |= cprop_insn (insn);
/* Keep track of everything modified by this insn. */
insn into a NOTE, or deleted the insn. */
if (! NOTE_P (insn) && ! insn->deleted ())
mark_oprs_set (insn);
+
+ if (!was_uncond_trap
+ && GET_CODE (PATTERN (insn)) == TRAP_IF
+ && XEXP (PATTERN (insn), 0) == const1_rtx)
+ {
+ /* If we have already seen an unconditional trap
+ earlier, the rest of the bb is going to be removed
+ as unreachable. Just turn it into a note, so that
+ RTL verification doesn't complain about it before
+ it is finally removed. */
+ if (seen_uncond_trap)
+ set_insn_deleted (insn);
+ else
+ {
+ seen_uncond_trap = true;
+ uncond_traps.safe_push (insn);
+ }
+ }
}
}
+ /* Make sure bypass_conditional_jumps will ignore not just its new
+ basic blocks, but also the ones after unconditional traps (those are
+ unreachable and will be eventually removed as such). */
+ bypass_last_basic_block = last_basic_block_for_fn (cfun);
+
+ while (!uncond_traps.is_empty ())
+ {
+ rtx_insn *insn = uncond_traps.pop ();
+ basic_block to_split = BLOCK_FOR_INSN (insn);
+ remove_edge (split_block (to_split, insn));
+ emit_barrier_after_bb (to_split);
+ }
+
changed |= bypass_conditional_jumps ();
FREE_REG_SET (reg_set_bitmap);
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