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/* Support routines for Value Range Propagation (VRP).
Copyright (C) 2005-2021 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 "backend.h"
#include "insn-codes.h"
#include "tree.h"
#include "gimple.h"
#include "ssa.h"
#include "optabs-tree.h"
#include "gimple-pretty-print.h"
#include "diagnostic-core.h"
#include "flags.h"
#include "fold-const.h"
#include "calls.h"
#include "cfganal.h"
#include "gimple-fold.h"
#include "gimple-iterator.h"
#include "tree-cfg.h"
#include "tree-ssa-loop-niter.h"
#include "tree-ssa-loop.h"
#include "intl.h"
#include "cfgloop.h"
#include "tree-scalar-evolution.h"
#include "tree-ssa-propagate.h"
#include "tree-chrec.h"
#include "omp-general.h"
#include "case-cfn-macros.h"
#include "alloc-pool.h"
#include "attribs.h"
#include "range.h"
#include "vr-values.h"
#include "cfghooks.h"
#include "range-op.h"
#include "gimple-range.h"
/* Set value range VR to a non-negative range of type TYPE. */
static inline void
set_value_range_to_nonnegative (value_range_equiv *vr, tree type)
{
tree zero = build_int_cst (type, 0);
vr->update (zero, vrp_val_max (type));
}
/* Set value range VR to a range of a truthvalue of type TYPE. */
static inline void
set_value_range_to_truthvalue (value_range_equiv *vr, tree type)
{
if (TYPE_PRECISION (type) == 1)
vr->set_varying (type);
else
vr->update (build_int_cst (type, 0), build_int_cst (type, 1));
}
/* Return the lattice entry for VAR or NULL if it doesn't exist or cannot
be initialized. */
value_range_equiv *
vr_values::get_lattice_entry (const_tree var)
{
value_range_equiv *vr;
tree sym;
unsigned ver = SSA_NAME_VERSION (var);
/* If we query the entry for a new SSA name avoid reallocating the lattice
since we should get here at most from the substitute-and-fold stage which
will never try to change values. */
if (ver >= num_vr_values)
return NULL;
vr = vr_value[ver];
if (vr)
return vr;
/* Create a default value range. */
vr = allocate_value_range_equiv ();
vr_value[ver] = vr;
/* After propagation finished return varying. */
if (values_propagated)
{
vr->set_varying (TREE_TYPE (var));
return vr;
}
vr->set_undefined ();
/* If VAR is a default definition of a parameter, the variable can
take any value in VAR's type. */
if (SSA_NAME_IS_DEFAULT_DEF (var))
{
sym = SSA_NAME_VAR (var);
if (TREE_CODE (sym) == PARM_DECL)
{
/* Try to use the "nonnull" attribute to create ~[0, 0]
anti-ranges for pointers. Note that this is only valid with
default definitions of PARM_DECLs. */
if (POINTER_TYPE_P (TREE_TYPE (sym))
&& (nonnull_arg_p (sym)
|| (get_global_range_query ()->range_of_expr (*vr,
const_cast <tree> (var))
&& vr->nonzero_p ())))
{
vr->set_nonzero (TREE_TYPE (sym));
vr->equiv_clear ();
}
else if (INTEGRAL_TYPE_P (TREE_TYPE (sym)))
{
get_global_range_query ()->range_of_expr (*vr, const_cast <tree> (var));
if (vr->undefined_p ())
vr->set_varying (TREE_TYPE (sym));
}
else
vr->set_varying (TREE_TYPE (sym));
}
else if (TREE_CODE (sym) == RESULT_DECL
&& DECL_BY_REFERENCE (sym))
{
vr->set_nonzero (TREE_TYPE (sym));
vr->equiv_clear ();
}
}
return vr;
}
/* Return value range information for VAR.
If we have no values ranges recorded (ie, VRP is not running), then
return NULL. Otherwise create an empty range if none existed for VAR. */
const value_range_equiv *
vr_values::get_value_range (const_tree var,
gimple *stmt ATTRIBUTE_UNUSED)
{
/* If we have no recorded ranges, then return NULL. */
if (!vr_value)
return NULL;
value_range_equiv *vr = get_lattice_entry (var);
/* Reallocate the lattice if needed. */
if (!vr)
{
unsigned int old_sz = num_vr_values;
num_vr_values = num_ssa_names + num_ssa_names / 10;
vr_value = XRESIZEVEC (value_range_equiv *, vr_value, num_vr_values);
for ( ; old_sz < num_vr_values; old_sz++)
vr_value [old_sz] = NULL;
/* Now that the lattice has been resized, we should never fail. */
vr = get_lattice_entry (var);
gcc_assert (vr);
}
return vr;
}
bool
vr_values::range_of_expr (irange &r, tree expr, gimple *stmt)
{
if (!gimple_range_ssa_p (expr))
return get_tree_range (r, expr, stmt);
if (const value_range *vr = get_value_range (expr, stmt))
{
if (vr->undefined_p () || vr->constant_p ())
r = *vr;
else
{
value_range tmp = *vr;
tmp.normalize_symbolics ();
r = tmp;
}
return true;
}
return false;
}
tree
vr_values::value_of_expr (tree op, gimple *)
{
return op_with_constant_singleton_value_range (op);
}
tree
vr_values::value_on_edge (edge, tree op)
{
return op_with_constant_singleton_value_range (op);
}
tree
vr_values::value_of_stmt (gimple *stmt, tree op)
{
if (!op)
op = gimple_get_lhs (stmt);
gcc_checking_assert (!op|| op == gimple_get_lhs (stmt));
if (op)
return op_with_constant_singleton_value_range (op);
return NULL_TREE;
}
/* Set the lattice entry for DEF to VARYING. */
void
vr_values::set_def_to_varying (const_tree def)
{
value_range_equiv *vr = get_lattice_entry (def);
if (vr)
vr->set_varying (TREE_TYPE (def));
}
/* Set value-ranges of all SSA names defined by STMT to varying. */
void
vr_values::set_defs_to_varying (gimple *stmt)
{
ssa_op_iter i;
tree def;
FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF)
set_def_to_varying (def);
}
/* Update the value range and equivalence set for variable VAR to
NEW_VR. Return true if NEW_VR is different from VAR's previous
value.
NOTE: This function assumes that NEW_VR is a temporary value range
object created for the sole purpose of updating VAR's range. The
storage used by the equivalence set from NEW_VR will be freed by
this function. Do not call update_value_range when NEW_VR
is the range object associated with another SSA name. */
bool
vr_values::update_value_range (const_tree var, value_range_equiv *new_vr)
{
value_range_equiv *old_vr;
bool is_new;
/* If there is a value-range on the SSA name from earlier analysis
factor that in. */
if (INTEGRAL_TYPE_P (TREE_TYPE (var)))
{
value_range_equiv nr;
get_global_range_query ()->range_of_expr (nr, const_cast <tree> (var));
if (!nr.undefined_p ())
new_vr->intersect (&nr);
}
/* Update the value range, if necessary. If we cannot allocate a lattice
entry for VAR keep it at VARYING. This happens when DOM feeds us stmts
with SSA names allocated after setting up the lattice. */
old_vr = get_lattice_entry (var);
if (!old_vr)
return false;
is_new = !old_vr->equal_p (*new_vr, /*ignore_equivs=*/false);
if (is_new)
{
/* Do not allow transitions up the lattice. The following
is slightly more awkward than just new_vr->type < old_vr->type
because VR_RANGE and VR_ANTI_RANGE need to be considered
the same. We may not have is_new when transitioning to
UNDEFINED. If old_vr->type is VARYING, we shouldn't be
called, if we are anyway, keep it VARYING. */
if (old_vr->varying_p ())
{
new_vr->set_varying (TREE_TYPE (var));
is_new = false;
}
else if (new_vr->undefined_p ())
{
old_vr->set_varying (TREE_TYPE (var));
new_vr->set_varying (TREE_TYPE (var));
return true;
}
else
old_vr->set (new_vr->min (), new_vr->max (), new_vr->equiv (),
new_vr->kind ());
}
new_vr->equiv_clear ();
return is_new;
}
/* Return true if value range VR involves exactly one symbol SYM. */
static bool
symbolic_range_based_on_p (value_range *vr, const_tree sym)
{
bool neg, min_has_symbol, max_has_symbol;
tree inv;
if (is_gimple_min_invariant (vr->min ()))
min_has_symbol = false;
else if (get_single_symbol (vr->min (), &neg, &inv) == sym)
min_has_symbol = true;
else
return false;
if (is_gimple_min_invariant (vr->max ()))
max_has_symbol = false;
else if (get_single_symbol (vr->max (), &neg, &inv) == sym)
max_has_symbol = true;
else
return false;
return (min_has_symbol || max_has_symbol);
}
/* Return true if the result of assignment STMT is know to be non-zero. */
static bool
gimple_assign_nonzero_p (gimple *stmt)
{
enum tree_code code = gimple_assign_rhs_code (stmt);
bool strict_overflow_p;
tree type = TREE_TYPE (gimple_assign_lhs (stmt));
switch (get_gimple_rhs_class (code))
{
case GIMPLE_UNARY_RHS:
return tree_unary_nonzero_warnv_p (gimple_assign_rhs_code (stmt),
type,
gimple_assign_rhs1 (stmt),
&strict_overflow_p);
case GIMPLE_BINARY_RHS:
return tree_binary_nonzero_warnv_p (gimple_assign_rhs_code (stmt),
type,
gimple_assign_rhs1 (stmt),
gimple_assign_rhs2 (stmt),
&strict_overflow_p);
case GIMPLE_TERNARY_RHS:
return false;
case GIMPLE_SINGLE_RHS:
return tree_single_nonzero_warnv_p (gimple_assign_rhs1 (stmt),
&strict_overflow_p);
case GIMPLE_INVALID_RHS:
gcc_unreachable ();
default:
gcc_unreachable ();
}
}
/* Return true if STMT is known to compute a non-zero value. */
static bool
gimple_stmt_nonzero_p (gimple *stmt)
{
switch (gimple_code (stmt))
{
case GIMPLE_ASSIGN:
return gimple_assign_nonzero_p (stmt);
case GIMPLE_CALL:
{
gcall *call_stmt = as_a<gcall *> (stmt);
return (gimple_call_nonnull_result_p (call_stmt)
|| gimple_call_nonnull_arg (call_stmt));
}
default:
gcc_unreachable ();
}
}
/* Like tree_expr_nonzero_p, but this function uses value ranges
obtained so far. */
bool
vr_values::vrp_stmt_computes_nonzero (gimple *stmt)
{
if (gimple_stmt_nonzero_p (stmt))
return true;
/* If we have an expression of the form &X->a, then the expression
is nonnull if X is nonnull. */
if (is_gimple_assign (stmt)
&& gimple_assign_rhs_code (stmt) == ADDR_EXPR)
{
tree expr = gimple_assign_rhs1 (stmt);
poly_int64 bitsize, bitpos;
tree offset;
machine_mode mode;
int unsignedp, reversep, volatilep;
tree base = get_inner_reference (TREE_OPERAND (expr, 0), &bitsize,
&bitpos, &offset, &mode, &unsignedp,
&reversep, &volatilep);
if (base != NULL_TREE
&& TREE_CODE (base) == MEM_REF
&& TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
{
poly_offset_int off = 0;
bool off_cst = false;
if (offset == NULL_TREE || TREE_CODE (offset) == INTEGER_CST)
{
off = mem_ref_offset (base);
if (offset)
off += poly_offset_int::from (wi::to_poly_wide (offset),
SIGNED);
off <<= LOG2_BITS_PER_UNIT;
off += bitpos;
off_cst = true;
}
/* If &X->a is equal to X and X is ~[0, 0], the result is too.
For -fdelete-null-pointer-checks -fno-wrapv-pointer we don't
allow going from non-NULL pointer to NULL. */
if ((off_cst && known_eq (off, 0))
|| (flag_delete_null_pointer_checks
&& !TYPE_OVERFLOW_WRAPS (TREE_TYPE (expr))))
{
const value_range_equiv *vr
= get_value_range (TREE_OPERAND (base, 0), stmt);
if (!range_includes_zero_p (vr))
return true;
}
/* If MEM_REF has a "positive" offset, consider it non-NULL
always, for -fdelete-null-pointer-checks also "negative"
ones. Punt for unknown offsets (e.g. variable ones). */
if (!TYPE_OVERFLOW_WRAPS (TREE_TYPE (expr))
&& off_cst
&& known_ne (off, 0)
&& (flag_delete_null_pointer_checks || known_gt (off, 0)))
return true;
}
}
return false;
}
/* Returns true if EXPR is a valid value (as expected by compare_values) --
a gimple invariant, or SSA_NAME +- CST. */
static bool
valid_value_p (tree expr)
{
if (TREE_CODE (expr) == SSA_NAME)
return true;
if (TREE_CODE (expr) == PLUS_EXPR
|| TREE_CODE (expr) == MINUS_EXPR)
return (TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME
&& TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST);
return is_gimple_min_invariant (expr);
}
/* If OP has a value range with a single constant value return that,
otherwise return NULL_TREE. This returns OP itself if OP is a
constant. */
tree
vr_values::op_with_constant_singleton_value_range (tree op)
{
if (is_gimple_min_invariant (op))
return op;
if (TREE_CODE (op) != SSA_NAME)
return NULL_TREE;
tree t;
if (get_value_range (op)->singleton_p (&t))
return t;
return NULL;
}
/* Return true if op is in a boolean [0, 1] value-range. */
bool
simplify_using_ranges::op_with_boolean_value_range_p (tree op, gimple *s)
{
if (TYPE_PRECISION (TREE_TYPE (op)) == 1)
return true;
if (integer_zerop (op)
|| integer_onep (op))
return true;
if (TREE_CODE (op) != SSA_NAME)
return false;
/* ?? Errr, this should probably check for [0,0] and [1,1] as well
as [0,1]. */
const value_range *vr = query->get_value_range (op, s);
return *vr == value_range (build_zero_cst (TREE_TYPE (op)),
build_one_cst (TREE_TYPE (op)));
}
/* Extract value range information for VAR when (OP COND_CODE LIMIT) is
true and store it in *VR_P. */
void
vr_values::extract_range_for_var_from_comparison_expr (tree var,
enum tree_code cond_code,
tree op, tree limit,
value_range_equiv *vr_p)
{
tree min, max, type;
const value_range_equiv *limit_vr;
type = TREE_TYPE (var);
/* For pointer arithmetic, we only keep track of pointer equality
and inequality. If we arrive here with unfolded conditions like
_1 > _1 do not derive anything. */
if ((POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR)
|| limit == var)
{
vr_p->set_varying (type);
return;
}
/* If LIMIT is another SSA name and LIMIT has a range of its own,
try to use LIMIT's range to avoid creating symbolic ranges
unnecessarily. */
limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL;
/* LIMIT's range is only interesting if it has any useful information. */
if (! limit_vr
|| limit_vr->undefined_p ()
|| limit_vr->varying_p ()
|| (limit_vr->symbolic_p ()
&& ! (limit_vr->kind () == VR_RANGE
&& (limit_vr->min () == limit_vr->max ()
|| operand_equal_p (limit_vr->min (),
limit_vr->max (), 0)))))
limit_vr = NULL;
/* Initially, the new range has the same set of equivalences of
VAR's range. This will be revised before returning the final
value. Since assertions may be chained via mutually exclusive
predicates, we will need to trim the set of equivalences before
we are done. */
gcc_assert (vr_p->equiv () == NULL);
vr_p->equiv_add (var, get_value_range (var), &vrp_equiv_obstack);
/* Extract a new range based on the asserted comparison for VAR and
LIMIT's value range. Notice that if LIMIT has an anti-range, we
will only use it for equality comparisons (EQ_EXPR). For any
other kind of assertion, we cannot derive a range from LIMIT's
anti-range that can be used to describe the new range. For
instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10],
then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is
no single range for x_2 that could describe LE_EXPR, so we might
as well build the range [b_4, +INF] for it.
One special case we handle is extracting a range from a
range test encoded as (unsigned)var + CST <= limit. */
if (TREE_CODE (op) == NOP_EXPR
|| TREE_CODE (op) == PLUS_EXPR)
{
if (TREE_CODE (op) == PLUS_EXPR)
{
min = fold_build1 (NEGATE_EXPR, TREE_TYPE (TREE_OPERAND (op, 1)),
TREE_OPERAND (op, 1));
max = int_const_binop (PLUS_EXPR, limit, min);
op = TREE_OPERAND (op, 0);
}
else
{
min = build_int_cst (TREE_TYPE (var), 0);
max = limit;
}
/* Make sure to not set TREE_OVERFLOW on the final type
conversion. We are willingly interpreting large positive
unsigned values as negative signed values here. */
min = force_fit_type (TREE_TYPE (var), wi::to_widest (min), 0, false);
max = force_fit_type (TREE_TYPE (var), wi::to_widest (max), 0, false);
/* We can transform a max, min range to an anti-range or
vice-versa. Use set_and_canonicalize which does this for
us. */
if (cond_code == LE_EXPR)
vr_p->set (min, max, vr_p->equiv ());
else if (cond_code == GT_EXPR)
vr_p->set (min, max, vr_p->equiv (), VR_ANTI_RANGE);
else
gcc_unreachable ();
}
else if (cond_code == EQ_EXPR)
{
enum value_range_kind range_kind;
if (limit_vr)
{
range_kind = limit_vr->kind ();
min = limit_vr->min ();
max = limit_vr->max ();
}
else
{
range_kind = VR_RANGE;
min = limit;
max = limit;
}
vr_p->update (min, max, range_kind);
/* When asserting the equality VAR == LIMIT and LIMIT is another
SSA name, the new range will also inherit the equivalence set
from LIMIT. */
if (TREE_CODE (limit) == SSA_NAME)
vr_p->equiv_add (limit, get_value_range (limit), &vrp_equiv_obstack);
}
else if (cond_code == NE_EXPR)
{
/* As described above, when LIMIT's range is an anti-range and
this assertion is an inequality (NE_EXPR), then we cannot
derive anything from the anti-range. For instance, if
LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does
not imply that VAR's range is [0, 0]. So, in the case of
anti-ranges, we just assert the inequality using LIMIT and
not its anti-range.
If LIMIT_VR is a range, we can only use it to build a new
anti-range if LIMIT_VR is a single-valued range. For
instance, if LIMIT_VR is [0, 1], the predicate
VAR != [0, 1] does not mean that VAR's range is ~[0, 1].
Rather, it means that for value 0 VAR should be ~[0, 0]
and for value 1, VAR should be ~[1, 1]. We cannot
represent these ranges.
The only situation in which we can build a valid
anti-range is when LIMIT_VR is a single-valued range
(i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case,
build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */
if (limit_vr
&& limit_vr->kind () == VR_RANGE
&& compare_values (limit_vr->min (), limit_vr->max ()) == 0)
{
min = limit_vr->min ();
max = limit_vr->max ();
}
else
{
/* In any other case, we cannot use LIMIT's range to build a
valid anti-range. */
min = max = limit;
}
/* If MIN and MAX cover the whole range for their type, then
just use the original LIMIT. */
if (INTEGRAL_TYPE_P (type)
&& vrp_val_is_min (min)
&& vrp_val_is_max (max))
min = max = limit;
vr_p->set (min, max, vr_p->equiv (), VR_ANTI_RANGE);
}
else if (cond_code == LE_EXPR || cond_code == LT_EXPR)
{
min = TYPE_MIN_VALUE (type);
if (limit_vr == NULL || limit_vr->kind () == VR_ANTI_RANGE)
max = limit;
else
{
/* If LIMIT_VR is of the form [N1, N2], we need to build the
range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for
LT_EXPR. */
max = limit_vr->max ();
}
/* If the maximum value forces us to be out of bounds, simply punt.
It would be pointless to try and do anything more since this
all should be optimized away above us. */
if (cond_code == LT_EXPR
&& compare_values (max, min) == 0)
vr_p->set_varying (TREE_TYPE (min));
else
{
/* For LT_EXPR, we create the range [MIN, MAX - 1]. */
if (cond_code == LT_EXPR)
{
if (TYPE_PRECISION (TREE_TYPE (max)) == 1
&& !TYPE_UNSIGNED (TREE_TYPE (max)))
max = fold_build2 (PLUS_EXPR, TREE_TYPE (max), max,
build_int_cst (TREE_TYPE (max), -1));
else
max = fold_build2 (MINUS_EXPR, TREE_TYPE (max), max,
build_int_cst (TREE_TYPE (max), 1));
/* Signal to compare_values_warnv this expr doesn't overflow. */
if (EXPR_P (max))
suppress_warning (max, OPT_Woverflow);
}
vr_p->update (min, max);
}
}
else if (cond_code == GE_EXPR || cond_code == GT_EXPR)
{
max = TYPE_MAX_VALUE (type);
if (limit_vr == NULL || limit_vr->kind () == VR_ANTI_RANGE)
min = limit;
else
{
/* If LIMIT_VR is of the form [N1, N2], we need to build the
range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for
GT_EXPR. */
min = limit_vr->min ();
}
/* If the minimum value forces us to be out of bounds, simply punt.
It would be pointless to try and do anything more since this
all should be optimized away above us. */
if (cond_code == GT_EXPR
&& compare_values (min, max) == 0)
vr_p->set_varying (TREE_TYPE (min));
else
{
/* For GT_EXPR, we create the range [MIN + 1, MAX]. */
if (cond_code == GT_EXPR)
{
if (TYPE_PRECISION (TREE_TYPE (min)) == 1
&& !TYPE_UNSIGNED (TREE_TYPE (min)))
min = fold_build2 (MINUS_EXPR, TREE_TYPE (min), min,
build_int_cst (TREE_TYPE (min), -1));
else
min = fold_build2 (PLUS_EXPR, TREE_TYPE (min), min,
build_int_cst (TREE_TYPE (min), 1));
/* Signal to compare_values_warnv this expr doesn't overflow. */
if (EXPR_P (min))
suppress_warning (min, OPT_Woverflow);
}
vr_p->update (min, max);
}
}
else
gcc_unreachable ();
/* Finally intersect the new range with what we already know about var. */
vr_p->intersect (get_value_range (var));
}
/* Extract value range information from an ASSERT_EXPR EXPR and store
it in *VR_P. */
void
vr_values::extract_range_from_assert (value_range_equiv *vr_p, tree expr)
{
tree var = ASSERT_EXPR_VAR (expr);
tree cond = ASSERT_EXPR_COND (expr);
tree limit, op;
enum tree_code cond_code;
gcc_assert (COMPARISON_CLASS_P (cond));
/* Find VAR in the ASSERT_EXPR conditional. */
if (var == TREE_OPERAND (cond, 0)
|| TREE_CODE (TREE_OPERAND (cond, 0)) == PLUS_EXPR
|| TREE_CODE (TREE_OPERAND (cond, 0)) == NOP_EXPR)
{
/* If the predicate is of the form VAR COMP LIMIT, then we just
take LIMIT from the RHS and use the same comparison code. */
cond_code = TREE_CODE (cond);
limit = TREE_OPERAND (cond, 1);
op = TREE_OPERAND (cond, 0);
}
else
{
/* If the predicate is of the form LIMIT COMP VAR, then we need
to flip around the comparison code to create the proper range
for VAR. */
cond_code = swap_tree_comparison (TREE_CODE (cond));
limit = TREE_OPERAND (cond, 0);
op = TREE_OPERAND (cond, 1);
}
extract_range_for_var_from_comparison_expr (var, cond_code, op,
limit, vr_p);
}
/* Extract range information from SSA name VAR and store it in VR. If
VAR has an interesting range, use it. Otherwise, create the
range [VAR, VAR] and return it. This is useful in situations where
we may have conditionals testing values of VARYING names. For
instance,
x_3 = y_5;
if (x_3 > y_5)
...
Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is
always false. */
void
vr_values::extract_range_from_ssa_name (value_range_equiv *vr, tree var)
{
const value_range_equiv *var_vr = get_value_range (var);
if (!var_vr->varying_p ())
vr->deep_copy (var_vr);
else
vr->set (var);
if (!vr->undefined_p ())
vr->equiv_add (var, get_value_range (var), &vrp_equiv_obstack);
}
/* Extract range information from a binary expression OP0 CODE OP1 based on
the ranges of each of its operands with resulting type EXPR_TYPE.
The resulting range is stored in *VR. */
void
vr_values::extract_range_from_binary_expr (value_range_equiv *vr,
enum tree_code code,
tree expr_type, tree op0, tree op1)
{
/* Get value ranges for each operand. For constant operands, create
a new value range with the operand to simplify processing. */
value_range vr0, vr1;
if (TREE_CODE (op0) == SSA_NAME)
vr0 = *(get_value_range (op0));
else if (is_gimple_min_invariant (op0))
vr0.set (op0);
else
vr0.set_varying (TREE_TYPE (op0));
if (TREE_CODE (op1) == SSA_NAME)
vr1 = *(get_value_range (op1));
else if (is_gimple_min_invariant (op1))
vr1.set (op1);
else
vr1.set_varying (TREE_TYPE (op1));
/* If one argument is varying, we can sometimes still deduce a
range for the output: any + [3, +INF] is in [MIN+3, +INF]. */
if (INTEGRAL_TYPE_P (TREE_TYPE (op0))
&& TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (op0)))
{
if (vr0.varying_p () && !vr1.varying_p ())
vr0 = value_range (vrp_val_min (expr_type), vrp_val_max (expr_type));
else if (vr1.varying_p () && !vr0.varying_p ())
vr1 = value_range (vrp_val_min (expr_type), vrp_val_max (expr_type));
}
range_fold_binary_expr (vr, code, expr_type, &vr0, &vr1);
/* Set value_range for n in following sequence:
def = __builtin_memchr (arg, 0, sz)
n = def - arg
Here the range for n can be set to [0, PTRDIFF_MAX - 1]. */
if (vr->varying_p ()
&& code == POINTER_DIFF_EXPR
&& TREE_CODE (op0) == SSA_NAME
&& TREE_CODE (op1) == SSA_NAME)
{
tree op0_ptype = TREE_TYPE (TREE_TYPE (op0));
tree op1_ptype = TREE_TYPE (TREE_TYPE (op1));
gcall *call_stmt = NULL;
if (TYPE_MODE (op0_ptype) == TYPE_MODE (char_type_node)
&& TYPE_PRECISION (op0_ptype) == TYPE_PRECISION (char_type_node)
&& TYPE_MODE (op1_ptype) == TYPE_MODE (char_type_node)
&& TYPE_PRECISION (op1_ptype) == TYPE_PRECISION (char_type_node)
&& (call_stmt = dyn_cast<gcall *>(SSA_NAME_DEF_STMT (op0)))
&& gimple_call_builtin_p (call_stmt, BUILT_IN_MEMCHR)
&& operand_equal_p (op0, gimple_call_lhs (call_stmt), 0)
&& operand_equal_p (op1, gimple_call_arg (call_stmt, 0), 0)
&& integer_zerop (gimple_call_arg (call_stmt, 1)))
{
tree max = vrp_val_max (ptrdiff_type_node);
wide_int wmax = wi::to_wide (max, TYPE_PRECISION (TREE_TYPE (max)));
tree range_min = build_zero_cst (expr_type);
tree range_max = wide_int_to_tree (expr_type, wmax - 1);
vr->set (range_min, range_max);
return;
}
}
/* Try harder for PLUS and MINUS if the range of one operand is symbolic
and based on the other operand, for example if it was deduced from a
symbolic comparison. When a bound of the range of the first operand
is invariant, we set the corresponding bound of the new range to INF
in order to avoid recursing on the range of the second operand. */
if (vr->varying_p ()
&& (code == PLUS_EXPR || code == MINUS_EXPR)
&& TREE_CODE (op1) == SSA_NAME
&& vr0.kind () == VR_RANGE
&& symbolic_range_based_on_p (&vr0, op1))
{
const bool minus_p = (code == MINUS_EXPR);
value_range n_vr1;
/* Try with VR0 and [-INF, OP1]. */
if (is_gimple_min_invariant (minus_p ? vr0.max () : vr0.min ()))
n_vr1.set (vrp_val_min (expr_type), op1);
/* Try with VR0 and [OP1, +INF]. */
else if (is_gimple_min_invariant (minus_p ? vr0.min () : vr0.max ()))
n_vr1.set (op1, vrp_val_max (expr_type));
/* Try with VR0 and [OP1, OP1]. */
else
n_vr1.set (op1, op1);
range_fold_binary_expr (vr, code, expr_type, &vr0, &n_vr1);
}
if (vr->varying_p ()
&& (code == PLUS_EXPR || code == MINUS_EXPR)
&& TREE_CODE (op0) == SSA_NAME
&& vr1.kind () == VR_RANGE
&& symbolic_range_based_on_p (&vr1, op0))
{
const bool minus_p = (code == MINUS_EXPR);
value_range n_vr0;
/* Try with [-INF, OP0] and VR1. */
if (is_gimple_min_invariant (minus_p ? vr1.max () : vr1.min ()))
n_vr0.set (vrp_val_min (expr_type), op0);
/* Try with [OP0, +INF] and VR1. */
else if (is_gimple_min_invariant (minus_p ? vr1.min (): vr1.max ()))
n_vr0.set (op0, vrp_val_max (expr_type));
/* Try with [OP0, OP0] and VR1. */
else
n_vr0.set (op0);
range_fold_binary_expr (vr, code, expr_type, &n_vr0, &vr1);
}
/* If we didn't derive a range for MINUS_EXPR, and
op1's range is ~[op0,op0] or vice-versa, then we
can derive a non-null range. This happens often for
pointer subtraction. */
if (vr->varying_p ()
&& (code == MINUS_EXPR || code == POINTER_DIFF_EXPR)
&& TREE_CODE (op0) == SSA_NAME
&& ((vr0.kind () == VR_ANTI_RANGE
&& vr0.min () == op1
&& vr0.min () == vr0.max ())
|| (vr1.kind () == VR_ANTI_RANGE
&& vr1.min () == op0
&& vr1.min () == vr1.max ())))
{
vr->set_nonzero (expr_type);
vr->equiv_clear ();
}
}
/* Extract range information from a unary expression CODE OP0 based on
the range of its operand with resulting type TYPE.
The resulting range is stored in *VR. */
void
vr_values::extract_range_from_unary_expr (value_range_equiv *vr,
enum tree_code code,
tree type, tree op0)
{
value_range vr0;
/* Get value ranges for the operand. For constant operands, create
a new value range with the operand to simplify processing. */
if (TREE_CODE (op0) == SSA_NAME)
vr0 = *(get_value_range (op0));
else if (is_gimple_min_invariant (op0))
vr0.set (op0);
else
vr0.set_varying (type);
range_fold_unary_expr (vr, code, type, &vr0, TREE_TYPE (op0));
}
/* Extract range information from a conditional expression STMT based on
the ranges of each of its operands and the expression code. */
void
vr_values::extract_range_from_cond_expr (value_range_equiv *vr, gassign *stmt)
{
/* Get value ranges for each operand. For constant operands, create
a new value range with the operand to simplify processing. */
tree op0 = gimple_assign_rhs2 (stmt);
value_range_equiv tem0;
const value_range_equiv *vr0 = &tem0;
if (TREE_CODE (op0) == SSA_NAME)
vr0 = get_value_range (op0);
else if (is_gimple_min_invariant (op0))
tem0.set (op0);
else
tem0.set_varying (TREE_TYPE (op0));
tree op1 = gimple_assign_rhs3 (stmt);
value_range_equiv tem1;
const value_range_equiv *vr1 = &tem1;
if (TREE_CODE (op1) == SSA_NAME)
vr1 = get_value_range (op1);
else if (is_gimple_min_invariant (op1))
tem1.set (op1);
else
tem1.set_varying (TREE_TYPE (op1));
/* The resulting value range is the union of the operand ranges */
vr->deep_copy (vr0);
vr->union_ (vr1);
}
/* Extract range information from a comparison expression EXPR based
on the range of its operand and the expression code. */
void
vr_values::extract_range_from_comparison (value_range_equiv *vr,
gimple *stmt)
{
enum tree_code code = gimple_assign_rhs_code (stmt);
tree type = TREE_TYPE (gimple_assign_lhs (stmt));
tree op0 = gimple_assign_rhs1 (stmt);
tree op1 = gimple_assign_rhs2 (stmt);
bool sop;
tree val
= simplifier.vrp_evaluate_conditional_warnv_with_ops (stmt, code, op0, op1,
false, &sop, NULL);
if (val)
{
/* Since this expression was found on the RHS of an assignment,
its type may be different from _Bool. Convert VAL to EXPR's
type. */
val = fold_convert (type, val);
if (is_gimple_min_invariant (val))
vr->set (val);
else
vr->update (val, val);
}
else
/* The result of a comparison is always true or false. */
set_value_range_to_truthvalue (vr, type);
}
/* Helper function for simplify_internal_call_using_ranges and
extract_range_basic. Return true if OP0 SUBCODE OP1 for
SUBCODE {PLUS,MINUS,MULT}_EXPR is known to never overflow or
always overflow. Set *OVF to true if it is known to always
overflow. */
static bool
check_for_binary_op_overflow (range_query *query,
enum tree_code subcode, tree type,
tree op0, tree op1, bool *ovf, gimple *s = NULL)
{
value_range vr0, vr1;
if (TREE_CODE (op0) == SSA_NAME)
vr0 = *query->get_value_range (op0, s);
else if (TREE_CODE (op0) == INTEGER_CST)
vr0.set (op0);
else
vr0.set_varying (TREE_TYPE (op0));
if (TREE_CODE (op1) == SSA_NAME)
vr1 = *query->get_value_range (op1, s);
else if (TREE_CODE (op1) == INTEGER_CST)
vr1.set (op1);
else
vr1.set_varying (TREE_TYPE (op1));
tree vr0min = vr0.min (), vr0max = vr0.max ();
tree vr1min = vr1.min (), vr1max = vr1.max ();
if (!range_int_cst_p (&vr0)
|| TREE_OVERFLOW (vr0min)
|| TREE_OVERFLOW (vr0max))
{
vr0min = vrp_val_min (TREE_TYPE (op0));
vr0max = vrp_val_max (TREE_TYPE (op0));
}
if (!range_int_cst_p (&vr1)
|| TREE_OVERFLOW (vr1min)
|| TREE_OVERFLOW (vr1max))
{
vr1min = vrp_val_min (TREE_TYPE (op1));
vr1max = vrp_val_max (TREE_TYPE (op1));
}
*ovf = arith_overflowed_p (subcode, type, vr0min,
subcode == MINUS_EXPR ? vr1max : vr1min);
if (arith_overflowed_p (subcode, type, vr0max,
subcode == MINUS_EXPR ? vr1min : vr1max) != *ovf)
return false;
if (subcode == MULT_EXPR)
{
if (arith_overflowed_p (subcode, type, vr0min, vr1max) != *ovf
|| arith_overflowed_p (subcode, type, vr0max, vr1min) != *ovf)
return false;
}
if (*ovf)
{
/* So far we found that there is an overflow on the boundaries.
That doesn't prove that there is an overflow even for all values
in between the boundaries. For that compute widest_int range
of the result and see if it doesn't overlap the range of
type. */
widest_int wmin, wmax;
widest_int w[4];
int i;
w[0] = wi::to_widest (vr0min);
w[1] = wi::to_widest (vr0max);
w[2] = wi::to_widest (vr1min);
w[3] = wi::to_widest (vr1max);
for (i = 0; i < 4; i++)
{
widest_int wt;
switch (subcode)
{
case PLUS_EXPR:
wt = wi::add (w[i & 1], w[2 + (i & 2) / 2]);
break;
case MINUS_EXPR:
wt = wi::sub (w[i & 1], w[2 + (i & 2) / 2]);
break;
case MULT_EXPR:
wt = wi::mul (w[i & 1], w[2 + (i & 2) / 2]);
break;
default:
gcc_unreachable ();
}
if (i == 0)
{
wmin = wt;
wmax = wt;
}
else
{
wmin = wi::smin (wmin, wt);
wmax = wi::smax (wmax, wt);
}
}
/* The result of op0 CODE op1 is known to be in range
[wmin, wmax]. */
widest_int wtmin = wi::to_widest (vrp_val_min (type));
widest_int wtmax = wi::to_widest (vrp_val_max (type));
/* If all values in [wmin, wmax] are smaller than
[wtmin, wtmax] or all are larger than [wtmin, wtmax],
the arithmetic operation will always overflow. */
if (wmax < wtmin || wmin > wtmax)
return true;
return false;
}
return true;
}
/* Derive a range from a builtin. Set range in VR and return TRUE if
successful. */
bool
vr_values::extract_range_from_ubsan_builtin (value_range_equiv *vr, gimple *stmt)
{
gcc_assert (is_gimple_call (stmt));
enum tree_code subcode = ERROR_MARK;
combined_fn cfn = gimple_call_combined_fn (stmt);
scalar_int_mode mode;
switch (cfn)
{
case CFN_UBSAN_CHECK_ADD:
subcode = PLUS_EXPR;
break;
case CFN_UBSAN_CHECK_SUB:
subcode = MINUS_EXPR;
break;
case CFN_UBSAN_CHECK_MUL:
subcode = MULT_EXPR;
break;
default:
break;
}
if (subcode != ERROR_MARK)
{
bool saved_flag_wrapv = flag_wrapv;
/* Pretend the arithmetics is wrapping. If there is
any overflow, we'll complain, but will actually do
wrapping operation. */
flag_wrapv = 1;
extract_range_from_binary_expr (vr, subcode,
TREE_TYPE (gimple_call_arg (stmt, 0)),
gimple_call_arg (stmt, 0),
gimple_call_arg (stmt, 1));
flag_wrapv = saved_flag_wrapv;
/* If for both arguments vrp_valueize returned non-NULL,
this should have been already folded and if not, it
wasn't folded because of overflow. Avoid removing the
UBSAN_CHECK_* calls in that case. */
if (vr->kind () == VR_RANGE
&& (vr->min () == vr->max ()
|| operand_equal_p (vr->min (), vr->max (), 0)))
vr->set_varying (vr->type ());
return !vr->varying_p ();
}
return false;
}
/* Try to derive a nonnegative or nonzero range out of STMT relying
primarily on generic routines in fold in conjunction with range data.
Store the result in *VR */
void
vr_values::extract_range_basic (value_range_equiv *vr, gimple *stmt)
{
bool sop;
if (is_gimple_call (stmt))
{
combined_fn cfn = gimple_call_combined_fn (stmt);
switch (cfn)
{
case CFN_UBSAN_CHECK_ADD:
case CFN_UBSAN_CHECK_SUB:
case CFN_UBSAN_CHECK_MUL:
if (extract_range_from_ubsan_builtin (vr, stmt))
return;
break;
default:
if (fold_range (*vr, stmt, this))
{
/* The original code nuked equivalences every time a
range was found, so do the same here. */
vr->equiv_clear ();
return;
}
break;
}
}
/* Handle extraction of the two results (result of arithmetics and
a flag whether arithmetics overflowed) from {ADD,SUB,MUL}_OVERFLOW
internal function. Similarly from ATOMIC_COMPARE_EXCHANGE. */
if (is_gimple_assign (stmt)
&& (gimple_assign_rhs_code (stmt) == REALPART_EXPR
|| gimple_assign_rhs_code (stmt) == IMAGPART_EXPR)
&& INTEGRAL_TYPE_P (TREE_TYPE (gimple_assign_lhs (stmt))))
{
enum tree_code code = gimple_assign_rhs_code (stmt);
tree op = gimple_assign_rhs1 (stmt);
tree type = TREE_TYPE (gimple_assign_lhs (stmt));
if (TREE_CODE (op) == code && TREE_CODE (TREE_OPERAND (op, 0)) == SSA_NAME)
{
gimple *g = SSA_NAME_DEF_STMT (TREE_OPERAND (op, 0));
if (is_gimple_call (g) && gimple_call_internal_p (g))
{
enum tree_code subcode = ERROR_MARK;
switch (gimple_call_internal_fn (g))
{
case IFN_ADD_OVERFLOW:
subcode = PLUS_EXPR;
break;
case IFN_SUB_OVERFLOW:
subcode = MINUS_EXPR;
break;
case IFN_MUL_OVERFLOW:
subcode = MULT_EXPR;
break;
case IFN_ATOMIC_COMPARE_EXCHANGE:
if (code == IMAGPART_EXPR)
{
/* This is the boolean return value whether compare and
exchange changed anything or not. */
vr->set (build_int_cst (type, 0),
build_int_cst (type, 1));
return;
}
break;
default:
break;
}
if (subcode != ERROR_MARK)
{
tree op0 = gimple_call_arg (g, 0);
tree op1 = gimple_call_arg (g, 1);
if (code == IMAGPART_EXPR)
{
bool ovf = false;
if (check_for_binary_op_overflow (this, subcode, type,
op0, op1, &ovf))
vr->set (build_int_cst (type, ovf));
else if (TYPE_PRECISION (type) == 1
&& !TYPE_UNSIGNED (type))
vr->set_varying (type);
else
vr->set (build_int_cst (type, 0),
build_int_cst (type, 1));
}
else if (types_compatible_p (type, TREE_TYPE (op0))
&& types_compatible_p (type, TREE_TYPE (op1)))
{
bool saved_flag_wrapv = flag_wrapv;
/* Pretend the arithmetics is wrapping. If there is
any overflow, IMAGPART_EXPR will be set. */
flag_wrapv = 1;
extract_range_from_binary_expr (vr, subcode, type,
op0, op1);
flag_wrapv = saved_flag_wrapv;
}
else
{
value_range_equiv vr0, vr1;
bool saved_flag_wrapv = flag_wrapv;
/* Pretend the arithmetics is wrapping. If there is
any overflow, IMAGPART_EXPR will be set. */
flag_wrapv = 1;
extract_range_from_unary_expr (&vr0, NOP_EXPR,
type, op0);
extract_range_from_unary_expr (&vr1, NOP_EXPR,
type, op1);
range_fold_binary_expr (vr, subcode, type, &vr0, &vr1);
flag_wrapv = saved_flag_wrapv;
}
return;
}
}
}
}
/* None of the below should need a 'type', but we are only called
for assignments and calls with a LHS. */
tree type = TREE_TYPE (gimple_get_lhs (stmt));
if (INTEGRAL_TYPE_P (type)
&& gimple_stmt_nonnegative_warnv_p (stmt, &sop))
set_value_range_to_nonnegative (vr, type);
else if (vrp_stmt_computes_nonzero (stmt))
{
vr->set_nonzero (type);
vr->equiv_clear ();
}
else
vr->set_varying (type);
}
/* Try to compute a useful range out of assignment STMT and store it
in *VR. */
void
vr_values::extract_range_from_assignment (value_range_equiv *vr, gassign *stmt)
{
enum tree_code code = gimple_assign_rhs_code (stmt);
if (code == ASSERT_EXPR)
extract_range_from_assert (vr, gimple_assign_rhs1 (stmt));
else if (code == SSA_NAME)
extract_range_from_ssa_name (vr, gimple_assign_rhs1 (stmt));
else if (TREE_CODE_CLASS (code) == tcc_binary)
extract_range_from_binary_expr (vr, gimple_assign_rhs_code (stmt),
TREE_TYPE (gimple_assign_lhs (stmt)),
gimple_assign_rhs1 (stmt),
gimple_assign_rhs2 (stmt));
else if (TREE_CODE_CLASS (code) == tcc_unary)
extract_range_from_unary_expr (vr, gimple_assign_rhs_code (stmt),
TREE_TYPE (gimple_assign_lhs (stmt)),
gimple_assign_rhs1 (stmt));
else if (code == COND_EXPR)
extract_range_from_cond_expr (vr, stmt);
else if (TREE_CODE_CLASS (code) == tcc_comparison)
extract_range_from_comparison (vr, stmt);
else if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS
&& is_gimple_min_invariant (gimple_assign_rhs1 (stmt)))
vr->set (gimple_assign_rhs1 (stmt));
else
vr->set_varying (TREE_TYPE (gimple_assign_lhs (stmt)));
if (vr->varying_p ())
extract_range_basic (vr, stmt);
}
/* Given two numeric value ranges VR0, VR1 and a comparison code COMP:
- Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for
all the values in the ranges.
- Return BOOLEAN_FALSE_NODE if the comparison always returns false.
- Return NULL_TREE if it is not always possible to determine the
value of the comparison.
Also set *STRICT_OVERFLOW_P to indicate whether comparision evaluation
assumed signed overflow is undefined. */
static tree
compare_ranges (enum tree_code comp, const value_range_equiv *vr0,
const value_range_equiv *vr1, bool *strict_overflow_p)
{
/* VARYING or UNDEFINED ranges cannot be compared. */
if (vr0->varying_p ()
|| vr0->undefined_p ()
|| vr1->varying_p ()
|| vr1->undefined_p ())
return NULL_TREE;
/* Anti-ranges need to be handled separately. */
if (vr0->kind () == VR_ANTI_RANGE || vr1->kind () == VR_ANTI_RANGE)
{
/* If both are anti-ranges, then we cannot compute any
comparison. */
if (vr0->kind () == VR_ANTI_RANGE && vr1->kind () == VR_ANTI_RANGE)
return NULL_TREE;
/* These comparisons are never statically computable. */
if (comp == GT_EXPR
|| comp == GE_EXPR
|| comp == LT_EXPR
|| comp == LE_EXPR)
return NULL_TREE;
/* Equality can be computed only between a range and an
anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */
if (vr0->kind () == VR_RANGE)
/* To simplify processing, make VR0 the anti-range. */
std::swap (vr0, vr1);
gcc_assert (comp == NE_EXPR || comp == EQ_EXPR);
if (compare_values_warnv (vr0->min (), vr1->min (), strict_overflow_p) == 0
&& compare_values_warnv (vr0->max (), vr1->max (), strict_overflow_p) == 0)
return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
return NULL_TREE;
}
/* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the
operands around and change the comparison code. */
if (comp == GT_EXPR || comp == GE_EXPR)
{
comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR;
std::swap (vr0, vr1);
}
if (comp == EQ_EXPR)
{
/* Equality may only be computed if both ranges represent
exactly one value. */
if (compare_values_warnv (vr0->min (), vr0->max (), strict_overflow_p) == 0
&& compare_values_warnv (vr1->min (), vr1->max (), strict_overflow_p) == 0)
{
int cmp_min = compare_values_warnv (vr0->min (), vr1->min (),
strict_overflow_p);
int cmp_max = compare_values_warnv (vr0->max (), vr1->max (),
strict_overflow_p);
if (cmp_min == 0 && cmp_max == 0)
return boolean_true_node;
else if (cmp_min != -2 && cmp_max != -2)
return boolean_false_node;
}
/* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */
else if (compare_values_warnv (vr0->min (), vr1->max (),
strict_overflow_p) == 1
|| compare_values_warnv (vr1->min (), vr0->max (),
strict_overflow_p) == 1)
return boolean_false_node;
return NULL_TREE;
}
else if (comp == NE_EXPR)
{
int cmp1, cmp2;
/* If VR0 is completely to the left or completely to the right
of VR1, they are always different. Notice that we need to
make sure that both comparisons yield similar results to
avoid comparing values that cannot be compared at
compile-time. */
cmp1 = compare_values_warnv (vr0->max (), vr1->min (), strict_overflow_p);
cmp2 = compare_values_warnv (vr0->min (), vr1->max (), strict_overflow_p);
if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1))
return boolean_true_node;
/* If VR0 and VR1 represent a single value and are identical,
return false. */
else if (compare_values_warnv (vr0->min (), vr0->max (),
strict_overflow_p) == 0
&& compare_values_warnv (vr1->min (), vr1->max (),
strict_overflow_p) == 0
&& compare_values_warnv (vr0->min (), vr1->min (),
strict_overflow_p) == 0
&& compare_values_warnv (vr0->max (), vr1->max (),
strict_overflow_p) == 0)
return boolean_false_node;
/* Otherwise, they may or may not be different. */
else
return NULL_TREE;
}
else if (comp == LT_EXPR || comp == LE_EXPR)
{
int tst;
/* If VR0 is to the left of VR1, return true. */
tst = compare_values_warnv (vr0->max (), vr1->min (), strict_overflow_p);
if ((comp == LT_EXPR && tst == -1)
|| (comp == LE_EXPR && (tst == -1 || tst == 0)))
return boolean_true_node;
/* If VR0 is to the right of VR1, return false. */
tst = compare_values_warnv (vr0->min (), vr1->max (), strict_overflow_p);
if ((comp == LT_EXPR && (tst == 0 || tst == 1))
|| (comp == LE_EXPR && tst == 1))
return boolean_false_node;
/* Otherwise, we don't know. */
return NULL_TREE;
}
gcc_unreachable ();
}
/* Given a value range VR, a value VAL and a comparison code COMP, return
BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the
values in VR. Return BOOLEAN_FALSE_NODE if the comparison
always returns false. Return NULL_TREE if it is not always
possible to determine the value of the comparison. Also set
*STRICT_OVERFLOW_P to indicate whether comparision evaluation
assumed signed overflow is undefined. */
static tree
compare_range_with_value (enum tree_code comp, const value_range *vr,
tree val, bool *strict_overflow_p)
{
if (vr->varying_p () || vr->undefined_p ())
return NULL_TREE;
/* Anti-ranges need to be handled separately. */
if (vr->kind () == VR_ANTI_RANGE)
{
/* For anti-ranges, the only predicates that we can compute at
compile time are equality and inequality. */
if (comp == GT_EXPR
|| comp == GE_EXPR
|| comp == LT_EXPR
|| comp == LE_EXPR)
return NULL_TREE;
/* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */
if (!vr->may_contain_p (val))
return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node;
return NULL_TREE;
}
if (comp == EQ_EXPR)
{
/* EQ_EXPR may only be computed if VR represents exactly
one value. */
if (compare_values_warnv (vr->min (), vr->max (), strict_overflow_p) == 0)
{
int cmp = compare_values_warnv (vr->min (), val, strict_overflow_p);
if (cmp == 0)
return boolean_true_node;
else if (cmp == -1 || cmp == 1 || cmp == 2)
return boolean_false_node;
}
else if (compare_values_warnv (val, vr->min (), strict_overflow_p) == -1
|| compare_values_warnv (vr->max (), val, strict_overflow_p) == -1)
return boolean_false_node;
return NULL_TREE;
}
else if (comp == NE_EXPR)
{
/* If VAL is not inside VR, then they are always different. */
if (compare_values_warnv (vr->max (), val, strict_overflow_p) == -1
|| compare_values_warnv (vr->min (), val, strict_overflow_p) == 1)
return boolean_true_node;
/* If VR represents exactly one value equal to VAL, then return
false. */
if (compare_values_warnv (vr->min (), vr->max (), strict_overflow_p) == 0
&& compare_values_warnv (vr->min (), val, strict_overflow_p) == 0)
return boolean_false_node;
/* Otherwise, they may or may not be different. */
return NULL_TREE;
}
else if (comp == LT_EXPR || comp == LE_EXPR)
{
int tst;
/* If VR is to the left of VAL, return true. */
tst = compare_values_warnv (vr->max (), val, strict_overflow_p);
if ((comp == LT_EXPR && tst == -1)
|| (comp == LE_EXPR && (tst == -1 || tst == 0)))
return boolean_true_node;
/* If VR is to the right of VAL, return false. */
tst = compare_values_warnv (vr->min (), val, strict_overflow_p);
if ((comp == LT_EXPR && (tst == 0 || tst == 1))
|| (comp == LE_EXPR && tst == 1))
return boolean_false_node;
/* Otherwise, we don't know. */
return NULL_TREE;
}
else if (comp == GT_EXPR || comp == GE_EXPR)
{
int tst;
/* If VR is to the right of VAL, return true. */
tst = compare_values_warnv (vr->min (), val, strict_overflow_p);
if ((comp == GT_EXPR && tst == 1)
|| (comp == GE_EXPR && (tst == 0 || tst == 1)))
return boolean_true_node;
/* If VR is to the left of VAL, return false. */
tst = compare_values_warnv (vr->max (), val, strict_overflow_p);
if ((comp == GT_EXPR && (tst == -1 || tst == 0))
|| (comp == GE_EXPR && tst == -1))
return boolean_false_node;
/* Otherwise, we don't know. */
return NULL_TREE;
}
gcc_unreachable ();
}
/* Given a VAR in STMT within LOOP, determine the bounds of the
variable and store it in MIN/MAX and return TRUE. If no bounds
could be determined, return FALSE. */
bool
bounds_of_var_in_loop (tree *min, tree *max, range_query *query,
class loop *loop, gimple *stmt, tree var)
{
tree init, step, chrec, tmin, tmax, type = TREE_TYPE (var);
enum ev_direction dir;
chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var));
/* Like in PR19590, scev can return a constant function. */
if (is_gimple_min_invariant (chrec))
{
*min = *max = chrec;
goto fix_overflow;
}
if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
return false;
init = initial_condition_in_loop_num (chrec, loop->num);
step = evolution_part_in_loop_num (chrec, loop->num);
if (!init || !step)
return false;
/* If INIT is an SSA with a singleton range, set INIT to said
singleton, otherwise leave INIT alone. */
if (TREE_CODE (init) == SSA_NAME)
query->get_value_range (init, stmt)->singleton_p (&init);
/* Likewise for step. */
if (TREE_CODE (step) == SSA_NAME)
query->get_value_range (step, stmt)->singleton_p (&step);
/* If STEP is symbolic, we can't know whether INIT will be the
minimum or maximum value in the range. Also, unless INIT is
a simple expression, compare_values and possibly other functions
in tree-vrp won't be able to handle it. */
if (step == NULL_TREE
|| !is_gimple_min_invariant (step)
|| !valid_value_p (init))
return false;
dir = scev_direction (chrec);
if (/* Do not adjust ranges if we do not know whether the iv increases
or decreases, ... */
dir == EV_DIR_UNKNOWN
/* ... or if it may wrap. */
|| scev_probably_wraps_p (NULL_TREE, init, step, stmt,
get_chrec_loop (chrec), true))
return false;
if (POINTER_TYPE_P (type) || !TYPE_MIN_VALUE (type))
tmin = lower_bound_in_type (type, type);
else
tmin = TYPE_MIN_VALUE (type);
if (POINTER_TYPE_P (type) || !TYPE_MAX_VALUE (type))
tmax = upper_bound_in_type (type, type);
else
tmax = TYPE_MAX_VALUE (type);
/* Try to use estimated number of iterations for the loop to constrain the
final value in the evolution. */
if (TREE_CODE (step) == INTEGER_CST
&& is_gimple_val (init)
&& (TREE_CODE (init) != SSA_NAME
|| query->get_value_range (init, stmt)->kind () == VR_RANGE))
{
widest_int nit;
/* We are only entering here for loop header PHI nodes, so using
the number of latch executions is the correct thing to use. */
if (max_loop_iterations (loop, &nit))
{
signop sgn = TYPE_SIGN (TREE_TYPE (step));
wi::overflow_type overflow;
widest_int wtmp = wi::mul (wi::to_widest (step), nit, sgn,
&overflow);
/* If the multiplication overflowed we can't do a meaningful
adjustment. Likewise if the result doesn't fit in the type
of the induction variable. For a signed type we have to
check whether the result has the expected signedness which
is that of the step as number of iterations is unsigned. */
if (!overflow
&& wi::fits_to_tree_p (wtmp, TREE_TYPE (init))
&& (sgn == UNSIGNED
|| wi::gts_p (wtmp, 0) == wi::gts_p (wi::to_wide (step), 0)))
{
value_range maxvr, vr0, vr1;
if (TREE_CODE (init) == SSA_NAME)
vr0 = *(query->get_value_range (init, stmt));
else if (is_gimple_min_invariant (init))
vr0.set (init);
else
vr0.set_varying (TREE_TYPE (init));
tree tem = wide_int_to_tree (TREE_TYPE (init), wtmp);
vr1.set (tem, tem);
range_fold_binary_expr (&maxvr, PLUS_EXPR,
TREE_TYPE (init), &vr0, &vr1);
/* Likewise if the addition did. */
if (maxvr.kind () == VR_RANGE)
{
value_range initvr;
if (TREE_CODE (init) == SSA_NAME)
initvr = *(query->get_value_range (init, stmt));
else if (is_gimple_min_invariant (init))
initvr.set (init);
else
return false;
/* Check if init + nit * step overflows. Though we checked
scev {init, step}_loop doesn't wrap, it is not enough
because the loop may exit immediately. Overflow could
happen in the plus expression in this case. */
if ((dir == EV_DIR_DECREASES
&& compare_values (maxvr.min (), initvr.min ()) != -1)
|| (dir == EV_DIR_GROWS
&& compare_values (maxvr.max (), initvr.max ()) != 1))
return false;
tmin = maxvr.min ();
tmax = maxvr.max ();
}
}
}
}
*min = tmin;
*max = tmax;
if (dir == EV_DIR_DECREASES)
*max = init;
else
*min = init;
fix_overflow:
/* Even for valid range info, sometimes overflow flag will leak in.
As GIMPLE IL should have no constants with TREE_OVERFLOW set, we
drop them. */
if (TREE_OVERFLOW_P (*min))
*min = drop_tree_overflow (*min);
if (TREE_OVERFLOW_P (*max))
*max = drop_tree_overflow (*max);
gcc_checking_assert (compare_values (*min, *max) != 1);
return true;
}
/* Given a range VR, a LOOP and a variable VAR, determine whether it
would be profitable to adjust VR using scalar evolution information
for VAR. If so, update VR with the new limits. */
void
vr_values::adjust_range_with_scev (value_range_equiv *vr, class loop *loop,
gimple *stmt, tree var)
{
tree min, max;
if (bounds_of_var_in_loop (&min, &max, this, loop, stmt, var))
{
if (vr->undefined_p () || vr->varying_p ())
{
/* For VARYING or UNDEFINED ranges, just about anything we get
from scalar evolutions should be better. */
vr->update (min, max);
}
else if (vr->kind () == VR_RANGE)
{
/* Start with the input range... */
tree vrmin = vr->min ();
tree vrmax = vr->max ();
/* ...and narrow it down with what we got from SCEV. */
if (compare_values (min, vrmin) == 1)
vrmin = min;
if (compare_values (max, vrmax) == -1)
vrmax = max;
vr->update (vrmin, vrmax);
}
else if (vr->kind () == VR_ANTI_RANGE)
{
/* ?? As an enhancement, if VR, MIN, and MAX are constants, one
could just intersect VR with a range of [MIN,MAX]. */
}
}
}
/* Dump value ranges of all SSA_NAMEs to FILE. */
void
vr_values::dump (FILE *file)
{
size_t i;
for (i = 0; i < num_vr_values; i++)
{
if (vr_value[i] && ssa_name (i))
{
print_generic_expr (file, ssa_name (i));
fprintf (file, ": ");
dump_value_range (file, vr_value[i]);
fprintf (file, "\n");
}
}
fprintf (file, "\n");
}
/* Initialize VRP lattice. */
vr_values::vr_values () : simplifier (this)
{
values_propagated = false;
num_vr_values = num_ssa_names * 2;
vr_value = XCNEWVEC (value_range_equiv *, num_vr_values);
vr_phi_edge_counts = XCNEWVEC (int, num_ssa_names);
bitmap_obstack_initialize (&vrp_equiv_obstack);
}
/* Free VRP lattice. */
vr_values::~vr_values ()
{
/* Free allocated memory. */
free (vr_value);
free (vr_phi_edge_counts);
bitmap_obstack_release (&vrp_equiv_obstack);
/* So that we can distinguish between VRP data being available
and not available. */
vr_value = NULL;
vr_phi_edge_counts = NULL;
}
/* A hack. */
static class vr_values *x_vr_values;
/* Return the singleton value-range for NAME or NAME. */
static inline tree
vrp_valueize (tree name)
{
if (TREE_CODE (name) == SSA_NAME)
{
const value_range_equiv *vr = x_vr_values->get_value_range (name);
if (vr->kind () == VR_RANGE
&& (TREE_CODE (vr->min ()) == SSA_NAME
|| is_gimple_min_invariant (vr->min ()))
&& vrp_operand_equal_p (vr->min (), vr->max ()))
return vr->min ();
}
return name;
}
/* Return the singleton value-range for NAME if that is a constant
but signal to not follow SSA edges. */
static inline tree
vrp_valueize_1 (tree name)
{
if (TREE_CODE (name) == SSA_NAME)
{
/* If the definition may be simulated again we cannot follow
this SSA edge as the SSA propagator does not necessarily
re-visit the use. */
gimple *def_stmt = SSA_NAME_DEF_STMT (name);
if (!gimple_nop_p (def_stmt)
&& prop_simulate_again_p (def_stmt))
return NULL_TREE;
const value_range_equiv *vr = x_vr_values->get_value_range (name);
tree singleton;
if (vr->singleton_p (&singleton))
return singleton;
}
return name;
}
/* Given STMT, an assignment or call, return its LHS if the type
of the LHS is suitable for VRP analysis, else return NULL_TREE. */
tree
get_output_for_vrp (gimple *stmt)
{
if (!is_gimple_assign (stmt) && !is_gimple_call (stmt))
return NULL_TREE;
/* We only keep track of ranges in integral and pointer types. */
tree lhs = gimple_get_lhs (stmt);
if (TREE_CODE (lhs) == SSA_NAME
&& ((INTEGRAL_TYPE_P (TREE_TYPE (lhs))
/* It is valid to have NULL MIN/MAX values on a type. See
build_range_type. */
&& TYPE_MIN_VALUE (TREE_TYPE (lhs))
&& TYPE_MAX_VALUE (TREE_TYPE (lhs)))
|| POINTER_TYPE_P (TREE_TYPE (lhs))))
return lhs;
return NULL_TREE;
}
/* Visit assignment STMT. If it produces an interesting range, record
the range in VR and set LHS to OUTPUT_P. */
void
vr_values::vrp_visit_assignment_or_call (gimple *stmt, tree *output_p,
value_range_equiv *vr)
{
tree lhs = get_output_for_vrp (stmt);
*output_p = lhs;
/* We only keep track of ranges in integral and pointer types. */
if (lhs)
{
enum gimple_code code = gimple_code (stmt);
/* Try folding the statement to a constant first. */
x_vr_values = this;
tree tem = gimple_fold_stmt_to_constant_1 (stmt, vrp_valueize,
vrp_valueize_1);
x_vr_values = NULL;
if (tem)
{
if (TREE_CODE (tem) == SSA_NAME
&& (SSA_NAME_IS_DEFAULT_DEF (tem)
|| ! prop_simulate_again_p (SSA_NAME_DEF_STMT (tem))))
{
extract_range_from_ssa_name (vr, tem);
return;
}
else if (is_gimple_min_invariant (tem))
{
vr->set (tem);
return;
}
}
/* Then dispatch to value-range extracting functions. */
if (code == GIMPLE_CALL)
extract_range_basic (vr, stmt);
else
extract_range_from_assignment (vr, as_a <gassign *> (stmt));
}
}
/* Helper that gets the value range of the SSA_NAME with version I
or a symbolic range containing the SSA_NAME only if the value range
is varying or undefined. Uses TEM as storage for the alternate range. */
const value_range_equiv *
simplify_using_ranges::get_vr_for_comparison (int i, value_range_equiv *tem,
gimple *s)
{
/* Shallow-copy equiv bitmap. */
const value_range_equiv *vr = query->get_value_range (ssa_name (i), s);
/* If name N_i does not have a valid range, use N_i as its own
range. This allows us to compare against names that may
have N_i in their ranges. */
if (vr->varying_p () || vr->undefined_p ())
{
tem->set (ssa_name (i));
return tem;
}
return vr;
}
/* Compare all the value ranges for names equivalent to VAR with VAL
using comparison code COMP. Return the same value returned by
compare_range_with_value, including the setting of
*STRICT_OVERFLOW_P. */
tree
simplify_using_ranges::compare_name_with_value
(enum tree_code comp, tree var, tree val,
bool *strict_overflow_p, bool use_equiv_p,
gimple *s)
{
/* Get the set of equivalences for VAR. */
bitmap e = query->get_value_range (var, s)->equiv ();
/* Start at -1. Set it to 0 if we do a comparison without relying
on overflow, or 1 if all comparisons rely on overflow. */
int used_strict_overflow = -1;
/* Compare vars' value range with val. */
value_range_equiv tem_vr;
const value_range_equiv *equiv_vr
= get_vr_for_comparison (SSA_NAME_VERSION (var), &tem_vr, s);
bool sop = false;
tree retval = compare_range_with_value (comp, equiv_vr, val, &sop);
if (retval)
used_strict_overflow = sop ? 1 : 0;
/* If the equiv set is empty we have done all work we need to do. */
if (e == NULL)
{
if (retval && used_strict_overflow > 0)
*strict_overflow_p = true;
return retval;
}
unsigned i;
bitmap_iterator bi;
EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
{
tree name = ssa_name (i);
if (!name)
continue;
if (!use_equiv_p
&& !SSA_NAME_IS_DEFAULT_DEF (name)
&& prop_simulate_again_p (SSA_NAME_DEF_STMT (name)))
continue;
equiv_vr = get_vr_for_comparison (i, &tem_vr, s);
sop = false;
tree t = compare_range_with_value (comp, equiv_vr, val, &sop);
if (t)
{
/* If we get different answers from different members
of the equivalence set this check must be in a dead
code region. Folding it to a trap representation
would be correct here. For now just return don't-know. */
if (retval != NULL
&& t != retval)
{
retval = NULL_TREE;
break;
}
retval = t;
if (!sop)
used_strict_overflow = 0;
else if (used_strict_overflow < 0)
used_strict_overflow = 1;
}
}
if (retval && used_strict_overflow > 0)
*strict_overflow_p = true;
return retval;
}
/* Given a comparison code COMP and names N1 and N2, compare all the
ranges equivalent to N1 against all the ranges equivalent to N2
to determine the value of N1 COMP N2. Return the same value
returned by compare_ranges. Set *STRICT_OVERFLOW_P to indicate
whether we relied on undefined signed overflow in the comparison. */
tree
simplify_using_ranges::compare_names (enum tree_code comp, tree n1, tree n2,
bool *strict_overflow_p, gimple *s)
{
/* Compare the ranges of every name equivalent to N1 against the
ranges of every name equivalent to N2. */
bitmap e1 = query->get_value_range (n1, s)->equiv ();
bitmap e2 = query->get_value_range (n2, s)->equiv ();
/* Use the fake bitmaps if e1 or e2 are not available. */
static bitmap s_e1 = NULL, s_e2 = NULL;
static bitmap_obstack *s_obstack = NULL;
if (s_obstack == NULL)
{
s_obstack = XNEW (bitmap_obstack);
bitmap_obstack_initialize (s_obstack);
s_e1 = BITMAP_ALLOC (s_obstack);
s_e2 = BITMAP_ALLOC (s_obstack);
}
if (e1 == NULL)
e1 = s_e1;
if (e2 == NULL)
e2 = s_e2;
/* Add N1 and N2 to their own set of equivalences to avoid
duplicating the body of the loop just to check N1 and N2
ranges. */
bitmap_set_bit (e1, SSA_NAME_VERSION (n1));
bitmap_set_bit (e2, SSA_NAME_VERSION (n2));
/* If the equivalence sets have a common intersection, then the two
names can be compared without checking their ranges. */
if (bitmap_intersect_p (e1, e2))
{
bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR)
? boolean_true_node
: boolean_false_node;
}
/* Start at -1. Set it to 0 if we do a comparison without relying
on overflow, or 1 if all comparisons rely on overflow. */
int used_strict_overflow = -1;
/* Otherwise, compare all the equivalent ranges. First, add N1 and
N2 to their own set of equivalences to avoid duplicating the body
of the loop just to check N1 and N2 ranges. */
bitmap_iterator bi1;
unsigned i1;
EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1)
{
if (!ssa_name (i1))
continue;
value_range_equiv tem_vr1;
const value_range_equiv *vr1 = get_vr_for_comparison (i1, &tem_vr1, s);
tree t = NULL_TREE, retval = NULL_TREE;
bitmap_iterator bi2;
unsigned i2;
EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2)
{
if (!ssa_name (i2))
continue;
bool sop = false;
value_range_equiv tem_vr2;
const value_range_equiv *vr2 = get_vr_for_comparison (i2, &tem_vr2,
s);
t = compare_ranges (comp, vr1, vr2, &sop);
if (t)
{
/* If we get different answers from different members
of the equivalence set this check must be in a dead
code region. Folding it to a trap representation
would be correct here. For now just return don't-know. */
if (retval != NULL && t != retval)
{
bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
return NULL_TREE;
}
retval = t;
if (!sop)
used_strict_overflow = 0;
else if (used_strict_overflow < 0)
used_strict_overflow = 1;
}
}
if (retval)
{
bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
if (used_strict_overflow > 0)
*strict_overflow_p = true;
return retval;
}
}
/* None of the equivalent ranges are useful in computing this
comparison. */
bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
return NULL_TREE;
}
/* Helper function for vrp_evaluate_conditional_warnv & other
optimizers. */
tree
simplify_using_ranges::vrp_evaluate_conditional_warnv_with_ops_using_ranges
(enum tree_code code, tree op0, tree op1, bool * strict_overflow_p,
gimple *s)
{
const value_range_equiv *vr0, *vr1;
vr0 = (TREE_CODE (op0) == SSA_NAME) ? query->get_value_range (op0, s) : NULL;
vr1 = (TREE_CODE (op1) == SSA_NAME) ? query->get_value_range (op1, s) : NULL;
tree res = NULL_TREE;
if (vr0 && vr1)
res = compare_ranges (code, vr0, vr1, strict_overflow_p);
if (!res && vr0)
res = compare_range_with_value (code, vr0, op1, strict_overflow_p);
if (!res && vr1)
res = (compare_range_with_value
(swap_tree_comparison (code), vr1, op0, strict_overflow_p));
return res;
}
/* Helper function for vrp_evaluate_conditional_warnv. */
tree
simplify_using_ranges::vrp_evaluate_conditional_warnv_with_ops
(gimple *stmt,
enum tree_code code,
tree op0, tree op1,
bool use_equiv_p,
bool *strict_overflow_p,
bool *only_ranges)
{
tree ret;
if (only_ranges)
*only_ranges = true;
/* We only deal with integral and pointer types. */
if (!INTEGRAL_TYPE_P (TREE_TYPE (op0))
&& !POINTER_TYPE_P (TREE_TYPE (op0)))
return NULL_TREE;
/* If OP0 CODE OP1 is an overflow comparison, if it can be expressed
as a simple equality test, then prefer that over its current form
for evaluation.
An overflow test which collapses to an equality test can always be
expressed as a comparison of one argument against zero. Overflow
occurs when the chosen argument is zero and does not occur if the
chosen argument is not zero. */
tree x;
if (overflow_comparison_p (code, op0, op1, use_equiv_p, &x))
{
wide_int max = wi::max_value (TYPE_PRECISION (TREE_TYPE (op0)), UNSIGNED);
/* B = A - 1; if (A < B) -> B = A - 1; if (A == 0)
B = A - 1; if (A > B) -> B = A - 1; if (A != 0)
B = A + 1; if (B < A) -> B = A + 1; if (B == 0)
B = A + 1; if (B > A) -> B = A + 1; if (B != 0) */
if (integer_zerop (x))
{
op1 = x;
code = (code == LT_EXPR || code == LE_EXPR) ? EQ_EXPR : NE_EXPR;
}
/* B = A + 1; if (A > B) -> B = A + 1; if (B == 0)
B = A + 1; if (A < B) -> B = A + 1; if (B != 0)
B = A - 1; if (B > A) -> B = A - 1; if (A == 0)
B = A - 1; if (B < A) -> B = A - 1; if (A != 0) */
else if (wi::to_wide (x) == max - 1)
{
op0 = op1;
op1 = wide_int_to_tree (TREE_TYPE (op0), 0);
code = (code == GT_EXPR || code == GE_EXPR) ? EQ_EXPR : NE_EXPR;
}
else
{
value_range vro, vri;
if (code == GT_EXPR || code == GE_EXPR)
{
vro.set (TYPE_MIN_VALUE (TREE_TYPE (op0)), x, VR_ANTI_RANGE);
vri.set (TYPE_MIN_VALUE (TREE_TYPE (op0)), x);
}
else if (code == LT_EXPR || code == LE_EXPR)
{
vro.set (TYPE_MIN_VALUE (TREE_TYPE (op0)), x);
vri.set (TYPE_MIN_VALUE (TREE_TYPE (op0)), x, VR_ANTI_RANGE);
}
else
gcc_unreachable ();
const value_range_equiv *vr0 = query->get_value_range (op0, stmt);
/* If vro, the range for OP0 to pass the overflow test, has
no intersection with *vr0, OP0's known range, then the
overflow test can't pass, so return the node for false.
If it is the inverted range, vri, that has no
intersection, then the overflow test must pass, so return
the node for true. In other cases, we could proceed with
a simplified condition comparing OP0 and X, with LE_EXPR
for previously LE_ or LT_EXPR and GT_EXPR otherwise, but
the comments next to the enclosing if suggest it's not
generally profitable to do so. */
vro.intersect (vr0);
if (vro.undefined_p ())
return boolean_false_node;
vri.intersect (vr0);
if (vri.undefined_p ())
return boolean_true_node;
}
}
if ((ret = vrp_evaluate_conditional_warnv_with_ops_using_ranges
(code, op0, op1, strict_overflow_p, stmt)))
return ret;
if (only_ranges)
*only_ranges = false;
/* Do not use compare_names during propagation, it's quadratic. */
if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME
&& use_equiv_p)
return compare_names (code, op0, op1, strict_overflow_p, stmt);
else if (TREE_CODE (op0) == SSA_NAME)
return compare_name_with_value (code, op0, op1,
strict_overflow_p, use_equiv_p, stmt);
else if (TREE_CODE (op1) == SSA_NAME)
return compare_name_with_value (swap_tree_comparison (code), op1, op0,
strict_overflow_p, use_equiv_p, stmt);
return NULL_TREE;
}
/* Given (CODE OP0 OP1) within STMT, try to simplify it based on value range
information. Return NULL if the conditional cannot be evaluated.
The ranges of all the names equivalent with the operands in COND
will be used when trying to compute the value. If the result is
based on undefined signed overflow, issue a warning if
appropriate. */
tree
simplify_using_ranges::vrp_evaluate_conditional (tree_code code, tree op0,
tree op1, gimple *stmt)
{
bool sop;
tree ret;
bool only_ranges;
/* Some passes and foldings leak constants with overflow flag set
into the IL. Avoid doing wrong things with these and bail out. */
if ((TREE_CODE (op0) == INTEGER_CST
&& TREE_OVERFLOW (op0))
|| (TREE_CODE (op1) == INTEGER_CST
&& TREE_OVERFLOW (op1)))
return NULL_TREE;
sop = false;
ret = vrp_evaluate_conditional_warnv_with_ops (stmt, code, op0, op1, true,
&sop, &only_ranges);
if (ret && sop)
{
enum warn_strict_overflow_code wc;
const char* warnmsg;
if (is_gimple_min_invariant (ret))
{
wc = WARN_STRICT_OVERFLOW_CONDITIONAL;
warnmsg = G_("assuming signed overflow does not occur when "
"simplifying conditional to constant");
}
else
{
wc = WARN_STRICT_OVERFLOW_COMPARISON;
warnmsg = G_("assuming signed overflow does not occur when "
"simplifying conditional");
}
if (issue_strict_overflow_warning (wc))
{
location_t location;
if (!gimple_has_location (stmt))
location = input_location;
else
location = gimple_location (stmt);
warning_at (location, OPT_Wstrict_overflow, "%s", warnmsg);
}
}
if (warn_type_limits
&& ret && only_ranges
&& TREE_CODE_CLASS (code) == tcc_comparison
&& TREE_CODE (op0) == SSA_NAME)
{
/* If the comparison is being folded and the operand on the LHS
is being compared against a constant value that is outside of
the natural range of OP0's type, then the predicate will
always fold regardless of the value of OP0. If -Wtype-limits
was specified, emit a warning. */
tree type = TREE_TYPE (op0);
const value_range_equiv *vr0 = query->get_value_range (op0, stmt);
if (vr0->varying_p ()
&& INTEGRAL_TYPE_P (type)
&& is_gimple_min_invariant (op1))
{
location_t location;
if (!gimple_has_location (stmt))
location = input_location;
else
location = gimple_location (stmt);
warning_at (location, OPT_Wtype_limits,
integer_zerop (ret)
? G_("comparison always false "
"due to limited range of data type")
: G_("comparison always true "
"due to limited range of data type"));
}
}
return ret;
}
/* Visit conditional statement STMT. If we can determine which edge
will be taken out of STMT's basic block, record it in
*TAKEN_EDGE_P. Otherwise, set *TAKEN_EDGE_P to NULL. */
void
simplify_using_ranges::vrp_visit_cond_stmt (gcond *stmt, edge *taken_edge_p)
{
tree val;
*taken_edge_p = NULL;
if (dump_file && (dump_flags & TDF_DETAILS))
{
tree use;
ssa_op_iter i;
fprintf (dump_file, "\nVisiting conditional with predicate: ");
print_gimple_stmt (dump_file, stmt, 0);
fprintf (dump_file, "\nWith known ranges\n");
FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
{
fprintf (dump_file, "\t");
print_generic_expr (dump_file, use);
fprintf (dump_file, ": ");
dump_value_range (dump_file, query->get_value_range (use, stmt));
}
fprintf (dump_file, "\n");
}
/* Compute the value of the predicate COND by checking the known
ranges of each of its operands.
Note that we cannot evaluate all the equivalent ranges here
because those ranges may not yet be final and with the current
propagation strategy, we cannot determine when the value ranges
of the names in the equivalence set have changed.
For instance, given the following code fragment
i_5 = PHI <8, i_13>
...
i_14 = ASSERT_EXPR <i_5, i_5 != 0>
if (i_14 == 1)
...
Assume that on the first visit to i_14, i_5 has the temporary
range [8, 8] because the second argument to the PHI function is
not yet executable. We derive the range ~[0, 0] for i_14 and the
equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for
the first time, since i_14 is equivalent to the range [8, 8], we
determine that the predicate is always false.
On the next round of propagation, i_13 is determined to be
VARYING, which causes i_5 to drop down to VARYING. So, another
visit to i_14 is scheduled. In this second visit, we compute the
exact same range and equivalence set for i_14, namely ~[0, 0] and
{ i_5 }. But we did not have the previous range for i_5
registered, so vrp_visit_assignment thinks that the range for
i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)'
is not visited again, which stops propagation from visiting
statements in the THEN clause of that if().
To properly fix this we would need to keep the previous range
value for the names in the equivalence set. This way we would've
discovered that from one visit to the other i_5 changed from
range [8, 8] to VR_VARYING.
However, fixing this apparent limitation may not be worth the
additional checking. Testing on several code bases (GCC, DLV,
MICO, TRAMP3D and SPEC2000) showed that doing this results in
4 more predicates folded in SPEC. */
bool sop;
val = vrp_evaluate_conditional_warnv_with_ops (stmt,
gimple_cond_code (stmt),
gimple_cond_lhs (stmt),
gimple_cond_rhs (stmt),
false, &sop, NULL);
if (val)
*taken_edge_p = find_taken_edge (gimple_bb (stmt), val);
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "\nPredicate evaluates to: ");
if (val == NULL_TREE)
fprintf (dump_file, "DON'T KNOW\n");
else
print_generic_stmt (dump_file, val);
}
}
/* Searches the case label vector VEC for the ranges of CASE_LABELs that are
used in range VR. The indices are placed in MIN_IDX1, MAX_IDX, MIN_IDX2 and
MAX_IDX2. If the ranges of CASE_LABELs are empty then MAX_IDX1 < MIN_IDX1.
Returns true if the default label is not needed. */
static bool
find_case_label_ranges (gswitch *stmt, const value_range *vr,
size_t *min_idx1, size_t *max_idx1,
size_t *min_idx2, size_t *max_idx2)
{
size_t i, j, k, l;
unsigned int n = gimple_switch_num_labels (stmt);
bool take_default;
tree case_low, case_high;
tree min = vr->min (), max = vr->max ();
gcc_checking_assert (!vr->varying_p () && !vr->undefined_p ());
take_default = !find_case_label_range (stmt, min, max, &i, &j);
/* Set second range to empty. */
*min_idx2 = 1;
*max_idx2 = 0;
if (vr->kind () == VR_RANGE)
{
*min_idx1 = i;
*max_idx1 = j;
return !take_default;
}
/* Set first range to all case labels. */
*min_idx1 = 1;
*max_idx1 = n - 1;
if (i > j)
return false;
/* Make sure all the values of case labels [i , j] are contained in
range [MIN, MAX]. */
case_low = CASE_LOW (gimple_switch_label (stmt, i));
case_high = CASE_HIGH (gimple_switch_label (stmt, j));
if (tree_int_cst_compare (case_low, min) < 0)
i += 1;
if (case_high != NULL_TREE
&& tree_int_cst_compare (max, case_high) < 0)
j -= 1;
if (i > j)
return false;
/* If the range spans case labels [i, j], the corresponding anti-range spans
the labels [1, i - 1] and [j + 1, n - 1]. */
k = j + 1;
l = n - 1;
if (k > l)
{
k = 1;
l = 0;
}
j = i - 1;
i = 1;
if (i > j)
{
i = k;
j = l;
k = 1;
l = 0;
}
*min_idx1 = i;
*max_idx1 = j;
*min_idx2 = k;
*max_idx2 = l;
return false;
}
/* Visit switch statement STMT. If we can determine which edge
will be taken out of STMT's basic block, record it in
*TAKEN_EDGE_P. Otherwise, *TAKEN_EDGE_P set to NULL. */
void
vr_values::vrp_visit_switch_stmt (gswitch *stmt, edge *taken_edge_p)
{
tree op, val;
const value_range_equiv *vr;
size_t i = 0, j = 0, k, l;
bool take_default;
*taken_edge_p = NULL;
op = gimple_switch_index (stmt);
if (TREE_CODE (op) != SSA_NAME)
return;
vr = get_value_range (op);
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "\nVisiting switch expression with operand ");
print_generic_expr (dump_file, op);
fprintf (dump_file, " with known range ");
dump_value_range (dump_file, vr);
fprintf (dump_file, "\n");
}
if (vr->undefined_p ()
|| vr->varying_p ()
|| vr->symbolic_p ())
return;
/* Find the single edge that is taken from the switch expression. */
take_default = !find_case_label_ranges (stmt, vr, &i, &j, &k, &l);
/* Check if the range spans no CASE_LABEL. If so, we only reach the default
label */
if (j < i)
{
gcc_assert (take_default);
val = gimple_switch_default_label (stmt);
}
else
{
/* Check if labels with index i to j and maybe the default label
are all reaching the same label. */
val = gimple_switch_label (stmt, i);
if (take_default
&& CASE_LABEL (gimple_switch_default_label (stmt))
!= CASE_LABEL (val))
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, " not a single destination for this "
"range\n");
return;
}
for (++i; i <= j; ++i)
{
if (CASE_LABEL (gimple_switch_label (stmt, i)) != CASE_LABEL (val))
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, " not a single destination for this "
"range\n");
return;
}
}
for (; k <= l; ++k)
{
if (CASE_LABEL (gimple_switch_label (stmt, k)) != CASE_LABEL (val))
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, " not a single destination for this "
"range\n");
return;
}
}
}
*taken_edge_p = find_edge (gimple_bb (stmt),
label_to_block (cfun, CASE_LABEL (val)));
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, " will take edge to ");
print_generic_stmt (dump_file, CASE_LABEL (val));
}
}
/* Evaluate statement STMT. If the statement produces a useful range,
set VR and corepsponding OUTPUT_P.
If STMT is a conditional branch and we can determine its truth
value, the taken edge is recorded in *TAKEN_EDGE_P. */
void
vr_values::extract_range_from_stmt (gimple *stmt, edge *taken_edge_p,
tree *output_p, value_range_equiv *vr)
{
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "\nextract_range_from_stmt visiting:\n");
print_gimple_stmt (dump_file, stmt, 0, dump_flags);
}
if (!stmt_interesting_for_vrp (stmt))
gcc_assert (stmt_ends_bb_p (stmt));
else if (is_gimple_assign (stmt) || is_gimple_call (stmt))
vrp_visit_assignment_or_call (stmt, output_p, vr);
else if (gimple_code (stmt) == GIMPLE_COND)
simplifier.vrp_visit_cond_stmt (as_a <gcond *> (stmt), taken_edge_p);
else if (gimple_code (stmt) == GIMPLE_SWITCH)
vrp_visit_switch_stmt (as_a <gswitch *> (stmt), taken_edge_p);
}
/* Visit all arguments for PHI node PHI that flow through executable
edges. If a valid value range can be derived from all the incoming
value ranges, set a new range in VR_RESULT. */
void
vr_values::extract_range_from_phi_node (gphi *phi,
value_range_equiv *vr_result)
{
tree lhs = PHI_RESULT (phi);
const value_range_equiv *lhs_vr = get_value_range (lhs);
bool first = true;
int old_edges;
class loop *l;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "\nVisiting PHI node: ");
print_gimple_stmt (dump_file, phi, 0, dump_flags);
}
bool may_simulate_backedge_again = false;
int edges = 0;
for (size_t i = 0; i < gimple_phi_num_args (phi); i++)
{
edge e = gimple_phi_arg_edge (phi, i);
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file,
" Argument #%d (%d -> %d %sexecutable)\n",
(int) i, e->src->index, e->dest->index,
(e->flags & EDGE_EXECUTABLE) ? "" : "not ");
}
if (e->flags & EDGE_EXECUTABLE)
{
value_range_equiv vr_arg_tem;
const value_range_equiv *vr_arg = &vr_arg_tem;
++edges;
tree arg = PHI_ARG_DEF (phi, i);
if (TREE_CODE (arg) == SSA_NAME)
{
/* See if we are eventually going to change one of the args. */
gimple *def_stmt = SSA_NAME_DEF_STMT (arg);
if (! gimple_nop_p (def_stmt)
&& prop_simulate_again_p (def_stmt)
&& e->flags & EDGE_DFS_BACK)
may_simulate_backedge_again = true;
const value_range_equiv *vr_arg_ = get_value_range (arg);
/* Do not allow equivalences or symbolic ranges to leak in from
backedges. That creates invalid equivalencies.
See PR53465 and PR54767. */
if (e->flags & EDGE_DFS_BACK)
{
if (!vr_arg_->varying_p () && !vr_arg_->undefined_p ())
{
vr_arg_tem.set (vr_arg_->min (), vr_arg_->max (), NULL,
vr_arg_->kind ());
if (vr_arg_tem.symbolic_p ())
vr_arg_tem.set_varying (TREE_TYPE (arg));
}
else
vr_arg = vr_arg_;
}
/* If the non-backedge arguments range is VR_VARYING then
we can still try recording a simple equivalence. */
else if (vr_arg_->varying_p ())
vr_arg_tem.set (arg);
else
vr_arg = vr_arg_;
}
else
{
if (TREE_OVERFLOW_P (arg))
arg = drop_tree_overflow (arg);
vr_arg_tem.set (arg);
}