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gimple-fold.c
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/* Statement simplification on GIMPLE.
Copyright (C) 2010-2020 Free Software Foundation, Inc.
Split out from tree-ssa-ccp.c.
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 "target.h"
#include "rtl.h"
#include "tree.h"
#include "gimple.h"
#include "predict.h"
#include "ssa.h"
#include "cgraph.h"
#include "gimple-pretty-print.h"
#include "gimple-ssa-warn-restrict.h"
#include "fold-const.h"
#include "stmt.h"
#include "expr.h"
#include "stor-layout.h"
#include "dumpfile.h"
#include "gimple-fold.h"
#include "gimplify.h"
#include "gimple-iterator.h"
#include "tree-into-ssa.h"
#include "tree-dfa.h"
#include "tree-object-size.h"
#include "tree-ssa.h"
#include "tree-ssa-propagate.h"
#include "ipa-utils.h"
#include "tree-ssa-address.h"
#include "langhooks.h"
#include "gimplify-me.h"
#include "dbgcnt.h"
#include "builtins.h"
#include "tree-eh.h"
#include "gimple-match.h"
#include "gomp-constants.h"
#include "optabs-query.h"
#include "omp-general.h"
#include "tree-cfg.h"
#include "fold-const-call.h"
#include "stringpool.h"
#include "attribs.h"
#include "asan.h"
#include "diagnostic-core.h"
#include "intl.h"
#include "calls.h"
#include "tree-vector-builder.h"
#include "tree-ssa-strlen.h"
#include "varasm.h"
enum strlen_range_kind {
/* Compute the exact constant string length. */
SRK_STRLEN,
/* Compute the maximum constant string length. */
SRK_STRLENMAX,
/* Compute a range of string lengths bounded by object sizes. When
the length of a string cannot be determined, consider as the upper
bound the size of the enclosing object the string may be a member
or element of. Also determine the size of the largest character
array the string may refer to. */
SRK_LENRANGE,
/* Determine the integer value of the argument (not string length). */
SRK_INT_VALUE
};
static bool
get_range_strlen (tree, bitmap *, strlen_range_kind, c_strlen_data *, unsigned);
/* Return true when DECL can be referenced from current unit.
FROM_DECL (if non-null) specify constructor of variable DECL was taken from.
We can get declarations that are not possible to reference for various
reasons:
1) When analyzing C++ virtual tables.
C++ virtual tables do have known constructors even
when they are keyed to other compilation unit.
Those tables can contain pointers to methods and vars
in other units. Those methods have both STATIC and EXTERNAL
set.
2) In WHOPR mode devirtualization might lead to reference
to method that was partitioned elsehwere.
In this case we have static VAR_DECL or FUNCTION_DECL
that has no corresponding callgraph/varpool node
declaring the body.
3) COMDAT functions referred by external vtables that
we devirtualize only during final compilation stage.
At this time we already decided that we will not output
the function body and thus we can't reference the symbol
directly. */
static bool
can_refer_decl_in_current_unit_p (tree decl, tree from_decl)
{
varpool_node *vnode;
struct cgraph_node *node;
symtab_node *snode;
if (DECL_ABSTRACT_P (decl))
return false;
/* We are concerned only about static/external vars and functions. */
if ((!TREE_STATIC (decl) && !DECL_EXTERNAL (decl))
|| !VAR_OR_FUNCTION_DECL_P (decl))
return true;
/* Static objects can be referred only if they are defined and not optimized
out yet. */
if (!TREE_PUBLIC (decl))
{
if (DECL_EXTERNAL (decl))
return false;
/* Before we start optimizing unreachable code we can be sure all
static objects are defined. */
if (symtab->function_flags_ready)
return true;
snode = symtab_node::get (decl);
if (!snode || !snode->definition)
return false;
node = dyn_cast <cgraph_node *> (snode);
return !node || !node->inlined_to;
}
/* We will later output the initializer, so we can refer to it.
So we are concerned only when DECL comes from initializer of
external var or var that has been optimized out. */
if (!from_decl
|| !VAR_P (from_decl)
|| (!DECL_EXTERNAL (from_decl)
&& (vnode = varpool_node::get (from_decl)) != NULL
&& vnode->definition)
|| (flag_ltrans
&& (vnode = varpool_node::get (from_decl)) != NULL
&& vnode->in_other_partition))
return true;
/* We are folding reference from external vtable. The vtable may reffer
to a symbol keyed to other compilation unit. The other compilation
unit may be in separate DSO and the symbol may be hidden. */
if (DECL_VISIBILITY_SPECIFIED (decl)
&& DECL_EXTERNAL (decl)
&& DECL_VISIBILITY (decl) != VISIBILITY_DEFAULT
&& (!(snode = symtab_node::get (decl)) || !snode->in_other_partition))
return false;
/* When function is public, we always can introduce new reference.
Exception are the COMDAT functions where introducing a direct
reference imply need to include function body in the curren tunit. */
if (TREE_PUBLIC (decl) && !DECL_COMDAT (decl))
return true;
/* We have COMDAT. We are going to check if we still have definition
or if the definition is going to be output in other partition.
Bypass this when gimplifying; all needed functions will be produced.
As observed in PR20991 for already optimized out comdat virtual functions
it may be tempting to not necessarily give up because the copy will be
output elsewhere when corresponding vtable is output.
This is however not possible - ABI specify that COMDATs are output in
units where they are used and when the other unit was compiled with LTO
it is possible that vtable was kept public while the function itself
was privatized. */
if (!symtab->function_flags_ready)
return true;
snode = symtab_node::get (decl);
if (!snode
|| ((!snode->definition || DECL_EXTERNAL (decl))
&& (!snode->in_other_partition
|| (!snode->forced_by_abi && !snode->force_output))))
return false;
node = dyn_cast <cgraph_node *> (snode);
return !node || !node->inlined_to;
}
/* Create a temporary for TYPE for a statement STMT. If the current function
is in SSA form, a SSA name is created. Otherwise a temporary register
is made. */
tree
create_tmp_reg_or_ssa_name (tree type, gimple *stmt)
{
if (gimple_in_ssa_p (cfun))
return make_ssa_name (type, stmt);
else
return create_tmp_reg (type);
}
/* CVAL is value taken from DECL_INITIAL of variable. Try to transform it into
acceptable form for is_gimple_min_invariant.
FROM_DECL (if non-NULL) specify variable whose constructor contains CVAL. */
tree
canonicalize_constructor_val (tree cval, tree from_decl)
{
if (CONSTANT_CLASS_P (cval))
return cval;
tree orig_cval = cval;
STRIP_NOPS (cval);
if (TREE_CODE (cval) == POINTER_PLUS_EXPR
&& TREE_CODE (TREE_OPERAND (cval, 1)) == INTEGER_CST)
{
tree ptr = TREE_OPERAND (cval, 0);
if (is_gimple_min_invariant (ptr))
cval = build1_loc (EXPR_LOCATION (cval),
ADDR_EXPR, TREE_TYPE (ptr),
fold_build2 (MEM_REF, TREE_TYPE (TREE_TYPE (ptr)),
ptr,
fold_convert (ptr_type_node,
TREE_OPERAND (cval, 1))));
}
if (TREE_CODE (cval) == ADDR_EXPR)
{
tree base = NULL_TREE;
if (TREE_CODE (TREE_OPERAND (cval, 0)) == COMPOUND_LITERAL_EXPR)
{
base = COMPOUND_LITERAL_EXPR_DECL (TREE_OPERAND (cval, 0));
if (base)
TREE_OPERAND (cval, 0) = base;
}
else
base = get_base_address (TREE_OPERAND (cval, 0));
if (!base)
return NULL_TREE;
if (VAR_OR_FUNCTION_DECL_P (base)
&& !can_refer_decl_in_current_unit_p (base, from_decl))
return NULL_TREE;
if (TREE_TYPE (base) == error_mark_node)
return NULL_TREE;
if (VAR_P (base))
TREE_ADDRESSABLE (base) = 1;
else if (TREE_CODE (base) == FUNCTION_DECL)
{
/* Make sure we create a cgraph node for functions we'll reference.
They can be non-existent if the reference comes from an entry
of an external vtable for example. */
cgraph_node::get_create (base);
}
/* Fixup types in global initializers. */
if (TREE_TYPE (TREE_TYPE (cval)) != TREE_TYPE (TREE_OPERAND (cval, 0)))
cval = build_fold_addr_expr (TREE_OPERAND (cval, 0));
if (!useless_type_conversion_p (TREE_TYPE (orig_cval), TREE_TYPE (cval)))
cval = fold_convert (TREE_TYPE (orig_cval), cval);
return cval;
}
/* In CONSTRUCTORs we may see unfolded constants like (int (*) ()) 0. */
if (TREE_CODE (cval) == INTEGER_CST)
{
if (TREE_OVERFLOW_P (cval))
cval = drop_tree_overflow (cval);
if (!useless_type_conversion_p (TREE_TYPE (orig_cval), TREE_TYPE (cval)))
cval = fold_convert (TREE_TYPE (orig_cval), cval);
return cval;
}
return orig_cval;
}
/* If SYM is a constant variable with known value, return the value.
NULL_TREE is returned otherwise. */
tree
get_symbol_constant_value (tree sym)
{
tree val = ctor_for_folding (sym);
if (val != error_mark_node)
{
if (val)
{
val = canonicalize_constructor_val (unshare_expr (val), sym);
if (val && is_gimple_min_invariant (val))
return val;
else
return NULL_TREE;
}
/* Variables declared 'const' without an initializer
have zero as the initializer if they may not be
overridden at link or run time. */
if (!val
&& is_gimple_reg_type (TREE_TYPE (sym)))
return build_zero_cst (TREE_TYPE (sym));
}
return NULL_TREE;
}
/* Subroutine of fold_stmt. We perform several simplifications of the
memory reference tree EXPR and make sure to re-gimplify them properly
after propagation of constant addresses. IS_LHS is true if the
reference is supposed to be an lvalue. */
static tree
maybe_fold_reference (tree expr, bool is_lhs)
{
tree result;
if ((TREE_CODE (expr) == VIEW_CONVERT_EXPR
|| TREE_CODE (expr) == REALPART_EXPR
|| TREE_CODE (expr) == IMAGPART_EXPR)
&& CONSTANT_CLASS_P (TREE_OPERAND (expr, 0)))
return fold_unary_loc (EXPR_LOCATION (expr),
TREE_CODE (expr),
TREE_TYPE (expr),
TREE_OPERAND (expr, 0));
else if (TREE_CODE (expr) == BIT_FIELD_REF
&& CONSTANT_CLASS_P (TREE_OPERAND (expr, 0)))
return fold_ternary_loc (EXPR_LOCATION (expr),
TREE_CODE (expr),
TREE_TYPE (expr),
TREE_OPERAND (expr, 0),
TREE_OPERAND (expr, 1),
TREE_OPERAND (expr, 2));
if (!is_lhs
&& (result = fold_const_aggregate_ref (expr))
&& is_gimple_min_invariant (result))
return result;
return NULL_TREE;
}
/* Attempt to fold an assignment statement pointed-to by SI. Returns a
replacement rhs for the statement or NULL_TREE if no simplification
could be made. It is assumed that the operands have been previously
folded. */
static tree
fold_gimple_assign (gimple_stmt_iterator *si)
{
gimple *stmt = gsi_stmt (*si);
enum tree_code subcode = gimple_assign_rhs_code (stmt);
location_t loc = gimple_location (stmt);
tree result = NULL_TREE;
switch (get_gimple_rhs_class (subcode))
{
case GIMPLE_SINGLE_RHS:
{
tree rhs = gimple_assign_rhs1 (stmt);
if (TREE_CLOBBER_P (rhs))
return NULL_TREE;
if (REFERENCE_CLASS_P (rhs))
return maybe_fold_reference (rhs, false);
else if (TREE_CODE (rhs) == OBJ_TYPE_REF)
{
tree val = OBJ_TYPE_REF_EXPR (rhs);
if (is_gimple_min_invariant (val))
return val;
else if (flag_devirtualize && virtual_method_call_p (rhs))
{
bool final;
vec <cgraph_node *>targets
= possible_polymorphic_call_targets (rhs, stmt, &final);
if (final && targets.length () <= 1 && dbg_cnt (devirt))
{
if (dump_enabled_p ())
{
dump_printf_loc (MSG_OPTIMIZED_LOCATIONS, stmt,
"resolving virtual function address "
"reference to function %s\n",
targets.length () == 1
? targets[0]->name ()
: "NULL");
}
if (targets.length () == 1)
{
val = fold_convert (TREE_TYPE (val),
build_fold_addr_expr_loc
(loc, targets[0]->decl));
STRIP_USELESS_TYPE_CONVERSION (val);
}
else
/* We cannot use __builtin_unreachable here because it
cannot have address taken. */
val = build_int_cst (TREE_TYPE (val), 0);
return val;
}
}
}
else if (TREE_CODE (rhs) == ADDR_EXPR)
{
tree ref = TREE_OPERAND (rhs, 0);
tree tem = maybe_fold_reference (ref, true);
if (tem
&& TREE_CODE (tem) == MEM_REF
&& integer_zerop (TREE_OPERAND (tem, 1)))
result = fold_convert (TREE_TYPE (rhs), TREE_OPERAND (tem, 0));
else if (tem)
result = fold_convert (TREE_TYPE (rhs),
build_fold_addr_expr_loc (loc, tem));
else if (TREE_CODE (ref) == MEM_REF
&& integer_zerop (TREE_OPERAND (ref, 1)))
result = fold_convert (TREE_TYPE (rhs), TREE_OPERAND (ref, 0));
if (result)
{
/* Strip away useless type conversions. Both the
NON_LVALUE_EXPR that may have been added by fold, and
"useless" type conversions that might now be apparent
due to propagation. */
STRIP_USELESS_TYPE_CONVERSION (result);
if (result != rhs && valid_gimple_rhs_p (result))
return result;
}
}
else if (TREE_CODE (rhs) == CONSTRUCTOR
&& TREE_CODE (TREE_TYPE (rhs)) == VECTOR_TYPE)
{
/* Fold a constant vector CONSTRUCTOR to VECTOR_CST. */
unsigned i;
tree val;
FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (rhs), i, val)
if (! CONSTANT_CLASS_P (val))
return NULL_TREE;
return build_vector_from_ctor (TREE_TYPE (rhs),
CONSTRUCTOR_ELTS (rhs));
}
else if (DECL_P (rhs))
return get_symbol_constant_value (rhs);
}
break;
case GIMPLE_UNARY_RHS:
break;
case GIMPLE_BINARY_RHS:
break;
case GIMPLE_TERNARY_RHS:
result = fold_ternary_loc (loc, subcode,
TREE_TYPE (gimple_assign_lhs (stmt)),
gimple_assign_rhs1 (stmt),
gimple_assign_rhs2 (stmt),
gimple_assign_rhs3 (stmt));
if (result)
{
STRIP_USELESS_TYPE_CONVERSION (result);
if (valid_gimple_rhs_p (result))
return result;
}
break;
case GIMPLE_INVALID_RHS:
gcc_unreachable ();
}
return NULL_TREE;
}
/* Replace a statement at *SI_P with a sequence of statements in STMTS,
adjusting the replacement stmts location and virtual operands.
If the statement has a lhs the last stmt in the sequence is expected
to assign to that lhs. */
static void
gsi_replace_with_seq_vops (gimple_stmt_iterator *si_p, gimple_seq stmts)
{
gimple *stmt = gsi_stmt (*si_p);
if (gimple_has_location (stmt))
annotate_all_with_location (stmts, gimple_location (stmt));
/* First iterate over the replacement statements backward, assigning
virtual operands to their defining statements. */
gimple *laststore = NULL;
for (gimple_stmt_iterator i = gsi_last (stmts);
!gsi_end_p (i); gsi_prev (&i))
{
gimple *new_stmt = gsi_stmt (i);
if ((gimple_assign_single_p (new_stmt)
&& !is_gimple_reg (gimple_assign_lhs (new_stmt)))
|| (is_gimple_call (new_stmt)
&& (gimple_call_flags (new_stmt)
& (ECF_NOVOPS | ECF_PURE | ECF_CONST | ECF_NORETURN)) == 0))
{
tree vdef;
if (!laststore)
vdef = gimple_vdef (stmt);
else
vdef = make_ssa_name (gimple_vop (cfun), new_stmt);
gimple_set_vdef (new_stmt, vdef);
if (vdef && TREE_CODE (vdef) == SSA_NAME)
SSA_NAME_DEF_STMT (vdef) = new_stmt;
laststore = new_stmt;
}
}
/* Second iterate over the statements forward, assigning virtual
operands to their uses. */
tree reaching_vuse = gimple_vuse (stmt);
for (gimple_stmt_iterator i = gsi_start (stmts);
!gsi_end_p (i); gsi_next (&i))
{
gimple *new_stmt = gsi_stmt (i);
/* If the new statement possibly has a VUSE, update it with exact SSA
name we know will reach this one. */
if (gimple_has_mem_ops (new_stmt))
gimple_set_vuse (new_stmt, reaching_vuse);
gimple_set_modified (new_stmt, true);
if (gimple_vdef (new_stmt))
reaching_vuse = gimple_vdef (new_stmt);
}
/* If the new sequence does not do a store release the virtual
definition of the original statement. */
if (reaching_vuse
&& reaching_vuse == gimple_vuse (stmt))
{
tree vdef = gimple_vdef (stmt);
if (vdef
&& TREE_CODE (vdef) == SSA_NAME)
{
unlink_stmt_vdef (stmt);
release_ssa_name (vdef);
}
}
/* Finally replace the original statement with the sequence. */
gsi_replace_with_seq (si_p, stmts, false);
}
/* Convert EXPR into a GIMPLE value suitable for substitution on the
RHS of an assignment. Insert the necessary statements before
iterator *SI_P. The statement at *SI_P, which must be a GIMPLE_CALL
is replaced. If the call is expected to produces a result, then it
is replaced by an assignment of the new RHS to the result variable.
If the result is to be ignored, then the call is replaced by a
GIMPLE_NOP. A proper VDEF chain is retained by making the first
VUSE and the last VDEF of the whole sequence be the same as the replaced
statement and using new SSA names for stores in between. */
void
gimplify_and_update_call_from_tree (gimple_stmt_iterator *si_p, tree expr)
{
tree lhs;
gimple *stmt, *new_stmt;
gimple_stmt_iterator i;
gimple_seq stmts = NULL;
stmt = gsi_stmt (*si_p);
gcc_assert (is_gimple_call (stmt));
push_gimplify_context (gimple_in_ssa_p (cfun));
lhs = gimple_call_lhs (stmt);
if (lhs == NULL_TREE)
{
gimplify_and_add (expr, &stmts);
/* We can end up with folding a memcpy of an empty class assignment
which gets optimized away by C++ gimplification. */
if (gimple_seq_empty_p (stmts))
{
pop_gimplify_context (NULL);
if (gimple_in_ssa_p (cfun))
{
unlink_stmt_vdef (stmt);
release_defs (stmt);
}
gsi_replace (si_p, gimple_build_nop (), false);
return;
}
}
else
{
tree tmp = force_gimple_operand (expr, &stmts, false, NULL_TREE);
new_stmt = gimple_build_assign (lhs, tmp);
i = gsi_last (stmts);
gsi_insert_after_without_update (&i, new_stmt,
GSI_CONTINUE_LINKING);
}
pop_gimplify_context (NULL);
gsi_replace_with_seq_vops (si_p, stmts);
}
/* Replace the call at *GSI with the gimple value VAL. */
void
replace_call_with_value (gimple_stmt_iterator *gsi, tree val)
{
gimple *stmt = gsi_stmt (*gsi);
tree lhs = gimple_call_lhs (stmt);
gimple *repl;
if (lhs)
{
if (!useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (val)))
val = fold_convert (TREE_TYPE (lhs), val);
repl = gimple_build_assign (lhs, val);
}
else
repl = gimple_build_nop ();
tree vdef = gimple_vdef (stmt);
if (vdef && TREE_CODE (vdef) == SSA_NAME)
{
unlink_stmt_vdef (stmt);
release_ssa_name (vdef);
}
gsi_replace (gsi, repl, false);
}
/* Replace the call at *GSI with the new call REPL and fold that
again. */
static void
replace_call_with_call_and_fold (gimple_stmt_iterator *gsi, gimple *repl)
{
gimple *stmt = gsi_stmt (*gsi);
gimple_call_set_lhs (repl, gimple_call_lhs (stmt));
gimple_set_location (repl, gimple_location (stmt));
gimple_move_vops (repl, stmt);
gsi_replace (gsi, repl, false);
fold_stmt (gsi);
}
/* Return true if VAR is a VAR_DECL or a component thereof. */
static bool
var_decl_component_p (tree var)
{
tree inner = var;
while (handled_component_p (inner))
inner = TREE_OPERAND (inner, 0);
return (DECL_P (inner)
|| (TREE_CODE (inner) == MEM_REF
&& TREE_CODE (TREE_OPERAND (inner, 0)) == ADDR_EXPR));
}
/* Return TRUE if the SIZE argument, representing the size of an
object, is in a range of values of which exactly zero is valid. */
static bool
size_must_be_zero_p (tree size)
{
if (integer_zerop (size))
return true;
if (TREE_CODE (size) != SSA_NAME || !INTEGRAL_TYPE_P (TREE_TYPE (size)))
return false;
tree type = TREE_TYPE (size);
int prec = TYPE_PRECISION (type);
/* Compute the value of SSIZE_MAX, the largest positive value that
can be stored in ssize_t, the signed counterpart of size_t. */
wide_int ssize_max = wi::lshift (wi::one (prec), prec - 1) - 1;
value_range valid_range (build_int_cst (type, 0),
wide_int_to_tree (type, ssize_max));
value_range vr;
get_range_info (size, vr);
vr.intersect (&valid_range);
return vr.zero_p ();
}
/* Fold function call to builtin mem{{,p}cpy,move}. Try to detect and
diagnose (otherwise undefined) overlapping copies without preventing
folding. When folded, GCC guarantees that overlapping memcpy has
the same semantics as memmove. Call to the library memcpy need not
provide the same guarantee. Return false if no simplification can
be made. */
static bool
gimple_fold_builtin_memory_op (gimple_stmt_iterator *gsi,
tree dest, tree src, enum built_in_function code)
{
gimple *stmt = gsi_stmt (*gsi);
tree lhs = gimple_call_lhs (stmt);
tree len = gimple_call_arg (stmt, 2);
tree destvar, srcvar;
location_t loc = gimple_location (stmt);
/* If the LEN parameter is a constant zero or in range where
the only valid value is zero, return DEST. */
if (size_must_be_zero_p (len))
{
gimple *repl;
if (gimple_call_lhs (stmt))
repl = gimple_build_assign (gimple_call_lhs (stmt), dest);
else
repl = gimple_build_nop ();
tree vdef = gimple_vdef (stmt);
if (vdef && TREE_CODE (vdef) == SSA_NAME)
{
unlink_stmt_vdef (stmt);
release_ssa_name (vdef);
}
gsi_replace (gsi, repl, false);
return true;
}
/* If SRC and DEST are the same (and not volatile), return
DEST{,+LEN,+LEN-1}. */
if (operand_equal_p (src, dest, 0))
{
/* Avoid diagnosing exact overlap in calls to __builtin_memcpy.
It's safe and may even be emitted by GCC itself (see bug
32667). */
unlink_stmt_vdef (stmt);
if (gimple_vdef (stmt) && TREE_CODE (gimple_vdef (stmt)) == SSA_NAME)
release_ssa_name (gimple_vdef (stmt));
if (!lhs)
{
gsi_replace (gsi, gimple_build_nop (), false);
return true;
}
goto done;
}
else
{
tree srctype, desttype;
unsigned int src_align, dest_align;
tree off0;
const char *tmp_str;
unsigned HOST_WIDE_INT tmp_len;
/* Build accesses at offset zero with a ref-all character type. */
off0 = build_int_cst (build_pointer_type_for_mode (char_type_node,
ptr_mode, true), 0);
/* If we can perform the copy efficiently with first doing all loads
and then all stores inline it that way. Currently efficiently
means that we can load all the memory into a single integer
register which is what MOVE_MAX gives us. */
src_align = get_pointer_alignment (src);
dest_align = get_pointer_alignment (dest);
if (tree_fits_uhwi_p (len)
&& compare_tree_int (len, MOVE_MAX) <= 0
/* FIXME: Don't transform copies from strings with known length.
Until GCC 9 this prevented a case in gcc.dg/strlenopt-8.c
from being handled, and the case was XFAILed for that reason.
Now that it is handled and the XFAIL removed, as soon as other
strlenopt tests that rely on it for passing are adjusted, this
hack can be removed. */
&& !c_strlen (src, 1)
&& !((tmp_str = c_getstr (src, &tmp_len)) != NULL
&& memchr (tmp_str, 0, tmp_len) == NULL))
{
unsigned ilen = tree_to_uhwi (len);
if (pow2p_hwi (ilen))
{
/* Detect out-of-bounds accesses without issuing warnings.
Avoid folding out-of-bounds copies but to avoid false
positives for unreachable code defer warning until after
DCE has worked its magic.
-Wrestrict is still diagnosed. */
if (int warning = check_bounds_or_overlap (as_a <gcall *>(stmt),
dest, src, len, len,
false, false))
if (warning != OPT_Wrestrict)
return false;
scalar_int_mode mode;
tree type = lang_hooks.types.type_for_size (ilen * 8, 1);
if (type
&& is_a <scalar_int_mode> (TYPE_MODE (type), &mode)
&& GET_MODE_SIZE (mode) * BITS_PER_UNIT == ilen * 8
/* If the destination pointer is not aligned we must be able
to emit an unaligned store. */
&& (dest_align >= GET_MODE_ALIGNMENT (mode)
|| !targetm.slow_unaligned_access (mode, dest_align)
|| (optab_handler (movmisalign_optab, mode)
!= CODE_FOR_nothing)))
{
tree srctype = type;
tree desttype = type;
if (src_align < GET_MODE_ALIGNMENT (mode))
srctype = build_aligned_type (type, src_align);
tree srcmem = fold_build2 (MEM_REF, srctype, src, off0);
tree tem = fold_const_aggregate_ref (srcmem);
if (tem)
srcmem = tem;
else if (src_align < GET_MODE_ALIGNMENT (mode)
&& targetm.slow_unaligned_access (mode, src_align)
&& (optab_handler (movmisalign_optab, mode)
== CODE_FOR_nothing))
srcmem = NULL_TREE;
if (srcmem)
{
gimple *new_stmt;
if (is_gimple_reg_type (TREE_TYPE (srcmem)))
{
new_stmt = gimple_build_assign (NULL_TREE, srcmem);
srcmem
= create_tmp_reg_or_ssa_name (TREE_TYPE (srcmem),
new_stmt);
gimple_assign_set_lhs (new_stmt, srcmem);
gimple_set_vuse (new_stmt, gimple_vuse (stmt));
gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
}
if (dest_align < GET_MODE_ALIGNMENT (mode))
desttype = build_aligned_type (type, dest_align);
new_stmt
= gimple_build_assign (fold_build2 (MEM_REF, desttype,
dest, off0),
srcmem);
gimple_move_vops (new_stmt, stmt);
if (!lhs)
{
gsi_replace (gsi, new_stmt, false);
return true;
}
gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
goto done;
}
}
}
}
if (code == BUILT_IN_MEMMOVE)
{
/* Both DEST and SRC must be pointer types.
??? This is what old code did. Is the testing for pointer types
really mandatory?
If either SRC is readonly or length is 1, we can use memcpy. */
if (!dest_align || !src_align)
return false;
if (readonly_data_expr (src)
|| (tree_fits_uhwi_p (len)
&& (MIN (src_align, dest_align) / BITS_PER_UNIT
>= tree_to_uhwi (len))))
{
tree fn = builtin_decl_implicit (BUILT_IN_MEMCPY);
if (!fn)
return false;
gimple_call_set_fndecl (stmt, fn);
gimple_call_set_arg (stmt, 0, dest);
gimple_call_set_arg (stmt, 1, src);
fold_stmt (gsi);
return true;
}
/* If *src and *dest can't overlap, optimize into memcpy as well. */
if (TREE_CODE (src) == ADDR_EXPR
&& TREE_CODE (dest) == ADDR_EXPR)
{
tree src_base, dest_base, fn;
poly_int64 src_offset = 0, dest_offset = 0;
poly_uint64 maxsize;
srcvar = TREE_OPERAND (src, 0);
src_base = get_addr_base_and_unit_offset (srcvar, &src_offset);
if (src_base == NULL)
src_base = srcvar;
destvar = TREE_OPERAND (dest, 0);
dest_base = get_addr_base_and_unit_offset (destvar,
&dest_offset);
if (dest_base == NULL)
dest_base = destvar;
if (!poly_int_tree_p (len, &maxsize))
maxsize = -1;
if (SSA_VAR_P (src_base)
&& SSA_VAR_P (dest_base))
{
if (operand_equal_p (src_base, dest_base, 0)
&& ranges_maybe_overlap_p (src_offset, maxsize,
dest_offset, maxsize))
return false;
}
else if (TREE_CODE (src_base) == MEM_REF
&& TREE_CODE (dest_base) == MEM_REF)
{
if (! operand_equal_p (TREE_OPERAND (src_base, 0),
TREE_OPERAND (dest_base, 0), 0))
return false;
poly_offset_int full_src_offset
= mem_ref_offset (src_base) + src_offset;
poly_offset_int full_dest_offset
= mem_ref_offset (dest_base) + dest_offset;
if (ranges_maybe_overlap_p (full_src_offset, maxsize,
full_dest_offset, maxsize))
return false;
}
else
return false;
fn = builtin_decl_implicit (BUILT_IN_MEMCPY);
if (!fn)
return false;
gimple_call_set_fndecl (stmt, fn);
gimple_call_set_arg (stmt, 0, dest);
gimple_call_set_arg (stmt, 1, src);
fold_stmt (gsi);
return true;
}
/* If the destination and source do not alias optimize into
memcpy as well. */
if ((is_gimple_min_invariant (dest)
|| TREE_CODE (dest) == SSA_NAME)
&& (is_gimple_min_invariant (src)
|| TREE_CODE (src) == SSA_NAME))
{
ao_ref destr, srcr;
ao_ref_init_from_ptr_and_size (&destr, dest, len);
ao_ref_init_from_ptr_and_size (&srcr, src, len);
if (!refs_may_alias_p_1 (&destr, &srcr, false))
{
tree fn;
fn = builtin_decl_implicit (BUILT_IN_MEMCPY);
if (!fn)
return false;
gimple_call_set_fndecl (stmt, fn);
gimple_call_set_arg (stmt, 0, dest);
gimple_call_set_arg (stmt, 1, src);
fold_stmt (gsi);
return true;
}
}
return false;
}
if (!tree_fits_shwi_p (len))
return false;
if (!POINTER_TYPE_P (TREE_TYPE (src))
|| !POINTER_TYPE_P (TREE_TYPE (dest)))
return false;
/* In the following try to find a type that is most natural to be
used for the memcpy source and destination and that allows
the most optimization when memcpy is turned into a plain assignment
using that type. In theory we could always use a char[len] type
but that only gains us that the destination and source possibly
no longer will have their address taken. */
srctype = TREE_TYPE (TREE_TYPE (src));
if (TREE_CODE (srctype) == ARRAY_TYPE
&& !tree_int_cst_equal (TYPE_SIZE_UNIT (srctype), len))
srctype = TREE_TYPE (srctype);
desttype = TREE_TYPE (TREE_TYPE (dest));
if (TREE_CODE (desttype) == ARRAY_TYPE
&& !tree_int_cst_equal (TYPE_SIZE_UNIT (desttype), len))
desttype = TREE_TYPE (desttype);
if (TREE_ADDRESSABLE (srctype)
|| TREE_ADDRESSABLE (desttype))
return false;
/* Make sure we are not copying using a floating-point mode or
a type whose size possibly does not match its precision. */
if (FLOAT_MODE_P (TYPE_MODE (desttype))
|| TREE_CODE (desttype) == BOOLEAN_TYPE
|| TREE_CODE (desttype) == ENUMERAL_TYPE)
desttype = bitwise_type_for_mode (TYPE_MODE (desttype));
if (FLOAT_MODE_P (TYPE_MODE (srctype))
|| TREE_CODE (srctype) == BOOLEAN_TYPE
|| TREE_CODE (srctype) == ENUMERAL_TYPE)
srctype = bitwise_type_for_mode (TYPE_MODE (srctype));
if (!srctype)
srctype = desttype;
if (!desttype)
desttype = srctype;
if (!srctype)
return false;
src_align = get_pointer_alignment (src);
dest_align = get_pointer_alignment (dest);
/* Choose between src and destination type for the access based
on alignment, whether the access constitutes a register access
and whether it may actually expose a declaration for SSA rewrite
or SRA decomposition. */
destvar = NULL_TREE;
srcvar = NULL_TREE;
if (TREE_CODE (dest) == ADDR_EXPR
&& var_decl_component_p (TREE_OPERAND (dest, 0))
&& tree_int_cst_equal (TYPE_SIZE_UNIT (desttype), len)
&& dest_align >= TYPE_ALIGN (desttype)