blob: 7fcfef41f7229f92830201c350cf82b861cbbcac [file] [log] [blame]
/* Statement simplification on GIMPLE.
Copyright (C) 2010-2021 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-access.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"
#include "memmodel.h"
#include "optabs.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))
/* ??? We should be able to assert that TREE_ADDRESSABLE is set,
but since the use can be in a debug stmt we can't. */
;
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 constant folding of the
memory reference tree EXPR. */
static tree
maybe_fold_reference (tree expr)
{
tree result = NULL_TREE;
if ((TREE_CODE (expr) == VIEW_CONVERT_EXPR
|| TREE_CODE (expr) == REALPART_EXPR
|| TREE_CODE (expr) == IMAGPART_EXPR)
&& CONSTANT_CLASS_P (TREE_OPERAND (expr, 0)))
result = 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)))
result = fold_ternary_loc (EXPR_LOCATION (expr),
TREE_CODE (expr),
TREE_TYPE (expr),
TREE_OPERAND (expr, 0),
TREE_OPERAND (expr, 1),
TREE_OPERAND (expr, 2));
else
result = fold_const_aggregate_ref (expr);
if (result && is_gimple_min_invariant (result))
return result;
return NULL_TREE;
}
/* Return true if EXPR is an acceptable right-hand-side for a
GIMPLE assignment. We validate the entire tree, not just
the root node, thus catching expressions that embed complex
operands that are not permitted in GIMPLE. This function
is needed because the folding routines in fold-const.c
may return such expressions in some cases, e.g., an array
access with an embedded index addition. It may make more
sense to have folding routines that are sensitive to the
constraints on GIMPLE operands, rather than abandoning any
any attempt to fold if the usual folding turns out to be too
aggressive. */
bool
valid_gimple_rhs_p (tree expr)
{
enum tree_code code = TREE_CODE (expr);
switch (TREE_CODE_CLASS (code))
{
case tcc_declaration:
if (!is_gimple_variable (expr))
return false;
break;
case tcc_constant:
/* All constants are ok. */
break;
case tcc_comparison:
/* GENERIC allows comparisons with non-boolean types, reject
those for GIMPLE. Let vector-typed comparisons pass - rules
for GENERIC and GIMPLE are the same here. */
if (!(INTEGRAL_TYPE_P (TREE_TYPE (expr))
&& (TREE_CODE (TREE_TYPE (expr)) == BOOLEAN_TYPE
|| TYPE_PRECISION (TREE_TYPE (expr)) == 1))
&& ! VECTOR_TYPE_P (TREE_TYPE (expr)))
return false;
/* Fallthru. */
case tcc_binary:
if (!is_gimple_val (TREE_OPERAND (expr, 0))
|| !is_gimple_val (TREE_OPERAND (expr, 1)))
return false;
break;
case tcc_unary:
if (!is_gimple_val (TREE_OPERAND (expr, 0)))
return false;
break;
case tcc_expression:
switch (code)
{
case ADDR_EXPR:
{
tree t;
if (is_gimple_min_invariant (expr))
return true;
t = TREE_OPERAND (expr, 0);
while (handled_component_p (t))
{
/* ??? More checks needed, see the GIMPLE verifier. */
if ((TREE_CODE (t) == ARRAY_REF
|| TREE_CODE (t) == ARRAY_RANGE_REF)
&& !is_gimple_val (TREE_OPERAND (t, 1)))
return false;
t = TREE_OPERAND (t, 0);
}
if (!is_gimple_id (t))
return false;
}
break;
default:
if (get_gimple_rhs_class (code) == GIMPLE_TERNARY_RHS)
{
if ((code == COND_EXPR
? !is_gimple_condexpr (TREE_OPERAND (expr, 0))
: !is_gimple_val (TREE_OPERAND (expr, 0)))
|| !is_gimple_val (TREE_OPERAND (expr, 1))
|| !is_gimple_val (TREE_OPERAND (expr, 2)))
return false;
break;
}
return false;
}
break;
case tcc_vl_exp:
return false;
case tcc_exceptional:
if (code == CONSTRUCTOR)
{
unsigned i;
tree elt;
FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (expr), i, elt)
if (!is_gimple_val (elt))
return false;
return true;
}
if (code != SSA_NAME)
return false;
break;
case tcc_reference:
if (code == BIT_FIELD_REF)
return is_gimple_val (TREE_OPERAND (expr, 0));
return false;
default:
return false;
}
return true;
}
/* 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);
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);
if (TREE_CODE (ref) == MEM_REF
&& integer_zerop (TREE_OPERAND (ref, 1)))
{
result = TREE_OPERAND (ref, 0);
if (!useless_type_conversion_p (TREE_TYPE (rhs),
TREE_TYPE (result)))
result = build1 (NOP_EXPR, TREE_TYPE (rhs), 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)
&& is_gimple_reg_type (TREE_TYPE (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);
}
/* Helper function for update_gimple_call and
gimplify_and_update_call_from_tree. A GIMPLE_CALL STMT is being replaced
with GIMPLE_CALL NEW_STMT. */
static void
finish_update_gimple_call (gimple_stmt_iterator *si_p, gimple *new_stmt,
gimple *stmt)
{
tree lhs = gimple_call_lhs (stmt);
gimple_call_set_lhs (new_stmt, lhs);
if (lhs && TREE_CODE (lhs) == SSA_NAME)
SSA_NAME_DEF_STMT (lhs) = new_stmt;
gimple_move_vops (new_stmt, stmt);
gimple_set_location (new_stmt, gimple_location (stmt));
if (gimple_block (new_stmt) == NULL_TREE)
gimple_set_block (new_stmt, gimple_block (stmt));
gsi_replace (si_p, new_stmt, false);
}
/* Update a GIMPLE_CALL statement at iterator *SI_P to call to FN
with number of arguments NARGS, where the arguments in GIMPLE form
follow NARGS argument. */
bool
update_gimple_call (gimple_stmt_iterator *si_p, tree fn, int nargs, ...)
{
va_list ap;
gcall *new_stmt, *stmt = as_a <gcall *> (gsi_stmt (*si_p));
gcc_assert (is_gimple_call (stmt));
va_start (ap, nargs);
new_stmt = gimple_build_call_valist (fn, nargs, ap);
finish_update_gimple_call (si_p, new_stmt, stmt);
va_end (ap);
return true;
}
/* Return true if EXPR is a CALL_EXPR suitable for representation
as a single GIMPLE_CALL statement. If the arguments require
further gimplification, return false. */
static bool
valid_gimple_call_p (tree expr)
{
unsigned i, nargs;
if (TREE_CODE (expr) != CALL_EXPR)
return false;
nargs = call_expr_nargs (expr);
for (i = 0; i < nargs; i++)
{
tree arg = CALL_EXPR_ARG (expr, i);
if (is_gimple_reg_type (TREE_TYPE (arg)))
{
if (!is_gimple_val (arg))
return false;
}
else
if (!is_gimple_lvalue (arg))
return false;
}
return true;
}
/* 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));
if (valid_gimple_call_p (expr))
{
/* The call has simplified to another call. */
tree fn = CALL_EXPR_FN (expr);
unsigned i;
unsigned nargs = call_expr_nargs (expr);
vec<tree> args = vNULL;
gcall *new_stmt;
if (nargs > 0)
{
args.create (nargs);
args.safe_grow_cleared (nargs, true);
for (i = 0; i < nargs; i++)
args[i] = CALL_EXPR_ARG (expr, i);
}
new_stmt = gimple_build_call_vec (fn, args);
finish_update_gimple_call (si_p, new_stmt, stmt);
args.release ();
return;
}
lhs = gimple_call_lhs (stmt);
if (lhs == NULL_TREE)
{
push_gimplify_context (gimple_in_ssa_p (cfun));
gimplify_and_add (expr, &stmts);
pop_gimplify_context (NULL);
/* 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))
{
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);
}
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;
if (cfun)
get_range_query (cfun)->range_of_expr (vr, size);
else
get_global_range_query ()->range_of_expr (vr, size);
if (vr.undefined_p ())
vr.set_varying (TREE_TYPE (size));
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);
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
{
/* We cannot (easily) change the type of the copy if it is a storage
order barrier, i.e. is equivalent to a VIEW_CONVERT_EXPR that can
modify the storage order of objects (see storage_order_barrier_p). */
tree srctype
= POINTER_TYPE_P (TREE_TYPE (src))
? TREE_TYPE (TREE_TYPE (src)) : NULL_TREE;
tree desttype
= POINTER_TYPE_P (TREE_TYPE (dest))
? TREE_TYPE (TREE_TYPE (dest)) : NULL_TREE;
tree destvar, srcvar, srcoff;
unsigned int src_align, dest_align;
unsigned HOST_WIDE_INT tmp_len;
const char *tmp_str;
/* Build accesses at offset zero with a ref-all character type. */
tree 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 with a single set operation and that the
total size is less than MOVE_MAX * MOVE_RATIO. */
src_align = get_pointer_alignment (src);
dest_align = get_pointer_alignment (dest);
if (tree_fits_uhwi_p (len)
&& (compare_tree_int
(len, (MOVE_MAX
* MOVE_RATIO (optimize_function_for_size_p (cfun))))
<= 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 = getbyterep (src, &tmp_len)) != NULL
&& memchr (tmp_str, 0, tmp_len) == NULL)
&& !(srctype
&& AGGREGATE_TYPE_P (srctype)
&& TYPE_REVERSE_STORAGE_ORDER (srctype))
&& !(desttype
&& AGGREGATE_TYPE_P (desttype)
&& TYPE_REVERSE_STORAGE_ORDER (desttype)))
{
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;
if (int_mode_for_size (ilen * 8, 0).exists (&mode)
&& GET_MODE_SIZE (mode) * BITS_PER_UNIT == ilen * 8
&& have_insn_for (SET, mode)
/* 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 type = build_nonstandard_integer_type (ilen * 8, 1);
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 (!srctype
|| (AGGREGATE_TYPE_P (srctype)
&& TYPE_REVERSE_STORAGE_ORDER (srctype)))
return false;
if (!desttype
|| (AGGREGATE_TYPE_P (desttype)
&& TYPE_REVERSE_STORAGE_ORDER (desttype)))
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. */
if (TREE_CODE (srctype) == ARRAY_TYPE
&& !tree_int_cst_equal (TYPE_SIZE_UNIT (srctype), len))
srctype = TREE_TYPE (srctype);
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. Also try to expose a string constant, we
might be able to concatenate several of them later into a single
string store. */
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)
&& (is_gimple_reg_type (desttype)
|| src_align >= TYPE_ALIGN (desttype)))
destvar = fold_build2 (MEM_REF, desttype, dest, off0);
else if (TREE_CODE (src) == ADDR_EXPR
&& var_decl_component_p (TREE_OPERAND (src, 0))
&& tree_int_cst_equal (TYPE_SIZE_UNIT (srctype), len)
&& src_align >= TYPE_ALIGN (srctype)
&& (is_gimple_reg_type (srctype)
|| dest_align >= TYPE_ALIGN (srctype)))
srcvar = fold_build2 (MEM_REF, srctype, src, off0);
/* FIXME: Don't transform copies from strings with known original length.
As soon as strlenopt tests that rely on it for passing are adjusted,
this hack can be removed. */
else if (gimple_call_alloca_for_var_p (stmt)
&& (srcvar = string_constant (src, &srcoff, NULL, NULL))
&& integer_zerop (srcoff)
&& tree_int_cst_equal (TYPE_SIZE_UNIT (TREE_TYPE (srcvar)), len)
&& dest_align >= TYPE_ALIGN (TREE_TYPE (srcvar)))
srctype = TREE_TYPE (srcvar);
else
return false;
/* Now that we chose an access type express the other side in
terms of it if the target allows that with respect to alignment
constraints. */
if (srcvar == NULL_TREE)
{
if (src_align >= TYPE_ALIGN (desttype))
srcvar = fold_build2 (MEM_REF, desttype, src, off0);
else
{
if (STRICT_ALIGNMENT)
return false;
srctype = build_aligned_type (TYPE_MAIN_VARIANT (desttype),
src_align);
srcvar = fold_build2 (MEM_REF, srctype, src, off0);
}
}
else if (destvar == NULL_TREE)
{
if (dest_align >= TYPE_ALIGN (srctype))
destvar = fold_build2 (MEM_REF, srctype, dest, off0);
else
{
if (STRICT_ALIGNMENT)
return false;
desttype = build_aligned_type (TYPE_MAIN_VARIANT (srctype),
dest_align);
destvar = fold_build2 (MEM_REF, desttype, dest, off0);
}
}
/* Same as above, 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;
gimple *new_stmt;
if (is_gimple_reg_type (TREE_TYPE (srcvar)))
{
tree tem = fold_const_aggregate_ref (srcvar);
if (tem)
srcvar = tem;
if (! is_gimple_min_invariant (srcvar))
{
new_stmt = gimple_build_assign (NULL_TREE, srcvar);
srcvar = create_tmp_reg_or_ssa_name (TREE_TYPE (srcvar),
new_stmt);
gimple_assign_set_lhs (new_stmt, srcvar);
gimple_set_vuse (new_stmt, gimple_vuse (stmt));
gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
}
new_stmt = gimple_build_assign (destvar, srcvar);
goto set_vop_and_replace;
}
/* We get an aggregate copy. If the source is a STRING_CST, then
directly use its type to perform the copy. */
if (TREE_CODE (srcvar) == STRING_CST)
desttype = srctype;
/* Or else, use an unsigned char[] type to perform the copy in order
to preserve padding and to avoid any issues with TREE_ADDRESSABLE
types or float modes behavior on copying. */
else
{
desttype = build_array_type_nelts (unsigned_char_type_node,
tree_to_uhwi (len));
srctype = desttype;
if (src_align > TYPE_ALIGN (srctype))
srctype = build_aligned_type (srctype, src_align);
srcvar = fold_build2 (MEM_REF, srctype, src, off0);
}
if (dest_align > TYPE_ALIGN (desttype))
desttype = build_aligned_type (desttype, dest_align);
destvar = fold_build2 (MEM_REF, desttype, dest, off0);
new_stmt = gimple_build_assign (destvar, srcvar);
set_vop_and_replace:
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);
}
done:
gimple_seq stmts = NULL;
if (code == BUILT_IN_MEMCPY || code == BUILT_IN_MEMMOVE)
len = NULL_TREE;
else if (code == BUILT_IN_MEMPCPY)
{
len = gimple_convert_to_ptrofftype (&stmts, loc, len);
dest = gimple_build (&stmts, loc, POINTER_PLUS_EXPR,
TREE_TYPE (dest), dest, len);
}
else
gcc_unreachable ();
gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
gimple *repl = gimple_build_assign (lhs, dest);
gsi_replace (gsi, repl, false);
return true;
}
/* Transform a call to built-in bcmp(a, b, len) at *GSI into one
to built-in memcmp (a, b, len). */
static bool
gimple_fold_builtin_bcmp (gimple_stmt_iterator *gsi)
{
tree fn = builtin_decl_implicit (BUILT_IN_MEMCMP);
if (!fn)
return false;
/* Transform bcmp (a, b, len) into memcmp (a, b, len). */
gimple *stmt = gsi_stmt (*gsi);
tree a = gimple_call_arg (stmt, 0);
tree b = gimple_call_arg (stmt, 1);
tree len = gimple_call_arg (stmt, 2);
gimple *repl = gimple_build_call (fn, 3, a, b, len);
replace_call_with_call_and_fold (gsi, repl);
return true;
}
/* Transform a call to built-in bcopy (src, dest, len) at *GSI into one
to built-in memmove (dest, src, len). */
static bool
gimple_fold_builtin_bcopy (gimple_stmt_iterator *gsi)
{
tree fn = builtin_decl_implicit (BUILT_IN_MEMMOVE);
if (!fn)
return false;
/* bcopy has been removed from POSIX in Issue 7 but Issue 6 specifies
it's quivalent to memmove (not memcpy). Transform bcopy (src, dest,
len) into memmove (dest, src, len). */
gimple *stmt = gsi_stmt (*gsi);
tree src = gimple_call_arg (stmt, 0);
tree dest = gimple_call_arg (stmt, 1);
tree len = gimple_call_arg (stmt, 2);
gimple *repl = gimple_build_call (fn, 3, dest, src, len);
gimple_call_set_fntype (as_a <gcall *> (stmt), TREE_TYPE (fn));
replace_call_with_call_and_fold (gsi, repl);
return true;
}
/* Transform a call to built-in bzero (dest, len) at *GSI into one
to built-in memset (dest, 0, len). */
static bool
gimple_fold_builtin_bzero (gimple_stmt_iterator *gsi)
{
tree fn = builtin_decl_implicit (BUILT_IN_MEMSET);
if (!fn)
return false;
/* Transform bzero (dest, len) into memset (dest, 0, len). */
gimple *stmt = gsi_stmt (*gsi);
tree dest = gimple_call_arg (stmt, 0);
tree len = gimple_call_arg (stmt, 1);
gimple_seq seq = NULL;
gimple *repl = gimple_build_call (fn, 3, dest, integer_zero_node, len);
gimple_seq_add_stmt_without_update (&seq, repl);
gsi_replace_with_seq_vops (gsi, seq);
fold_stmt (gsi);
return true;
}
/* Fold function call to builtin memset or bzero at *GSI setting the
memory of size LEN to VAL. Return whether a simplification was made. */
static bool
gimple_fold_builtin_memset (gimple_stmt_iterator *gsi, tree c, tree len)
{
gimple *stmt = gsi_stmt (*gsi);
tree etype;
unsigned HOST_WIDE_INT length, cval;
/* If the LEN parameter is zero, return DEST. */
if (integer_zerop (len))
{
replace_call_with_value (gsi, gimple_call_arg (stmt, 0));
return true;
}
if (! tree_fits_uhwi_p (len))
return false;
if (TREE_CODE (c) != INTEGER_CST)
return false;
tree dest = gimple_call_arg (stmt, 0);
tree var = dest;
if (TREE_CODE (var) != ADDR_EXPR)
return false;
var = TREE_OPERAND (var, 0);
if (TREE_THIS_VOLATILE (var))
return false;
etype = TREE_TYPE (var);
if (TREE_CODE (etype) == ARRAY_TYPE)
etype = TREE_TYPE (etype);
if (!INTEGRAL_TYPE_P (etype)
&& !POINTER_TYPE_P (etype))
return NULL_TREE;
if (! var_decl_component_p (var))
return NULL_TREE;
length = tree_to_uhwi (len);
if (GET_MODE_SIZE (SCALAR_INT_TYPE_MODE (etype)) != length
|| (GET_MODE_PRECISION (SCALAR_INT_TYPE_MODE (etype))
!= GET_MODE_BITSIZE (SCALAR_INT_TYPE_MODE (etype)))
|| get_pointer_alignment (dest) / BITS_PER_UNIT < length)
return NULL_TREE;
if (length > HOST_BITS_PER_WIDE_INT / BITS_PER_UNIT)
return NULL_TREE;
if (!type_has_mode_precision_p (etype))
etype = lang_hooks.types.type_for_mode (SCALAR_INT_TYPE_MODE (etype),
TYPE_UNSIGNED (etype));
if (integer_zerop (c))
cval = 0;
else
{
if (CHAR_BIT != 8 || BITS_PER_UNIT != 8 || HOST_BITS_PER_WIDE_INT > 64)
return NULL_TREE;
cval = TREE_INT_CST_LOW (c);
cval &= 0xff;
cval |= cval << 8;
cval |= cval << 16;
cval |= (cval << 31) << 1;
}
var = fold_build2 (MEM_REF, etype, dest, build_int_cst (ptr_type_node, 0));
gimple *store = gimple_build_assign (var, build_int_cst_type (etype, cval));
gimple_move_vops (store, stmt);
gsi_insert_before (gsi, store, GSI_SAME_STMT);
if (gimple_call_lhs (stmt))
{
gimple *asgn = gimple_build_assign (gimple_call_lhs (stmt), dest);
gsi_replace (gsi, asgn, false);
}
else
{
gimple_stmt_iterator gsi2 = *gsi;
gsi_prev (gsi);
gsi_remove (&gsi2, true);
}
return true;
}
/* Helper of get_range_strlen for ARG that is not an SSA_NAME. */
static bool
get_range_strlen_tree (tree arg, bitmap *visited, strlen_range_kind rkind,
c_strlen_data *pdata, unsigned eltsize)
{
gcc_assert (TREE_CODE (arg) != SSA_NAME);
/* The length computed by this invocation of the function. */
tree val = NULL_TREE;
/* True if VAL is an optimistic (tight) bound determined from
the size of the character array in which the string may be
stored. In that case, the computed VAL is used to set
PDATA->MAXBOUND. */
bool tight_bound = false;
/* We can end up with &(*iftmp_1)[0] here as well, so handle it. */
if (TREE_CODE (arg) == ADDR_EXPR
&& TREE_CODE (TREE_OPERAND (arg, 0)) == ARRAY_REF)
{
tree op = TREE_OPERAND (arg, 0);
if (integer_zerop (TREE_OPERAND (op, 1)))
{
tree aop0 = TREE_OPERAND (op, 0);
if (TREE_CODE (aop0) == INDIRECT_REF
&& TREE_CODE (TREE_OPERAND (aop0, 0)) == SSA_NAME)
return get_range_strlen (TREE_OPERAND (aop0, 0), visited, rkind,
pdata, eltsize);
}
else if (TREE_CODE (TREE_OPERAND (op, 0)) == COMPONENT_REF
&& rkind == SRK_LENRANGE)
{
/* Fail if an array is the last member of a struct object
since it could be treated as a (fake) flexible array
member. */
tree idx = TREE_OPERAND (op, 1);
arg = TREE_OPERAND (op, 0);
tree optype = TREE_TYPE (arg);
if (tree dom = TYPE_DOMAIN (optype))
if (tree bound = TYPE_MAX_VALUE (dom))
if (TREE_CODE (bound) == INTEGER_CST
&& TREE_CODE (idx) == INTEGER_CST
&& tree_int_cst_lt (bound, idx))
return false;
}
}
if (rkind == SRK_INT_VALUE)
{
/* We are computing the maximum value (not string length). */
val = arg;
if (TREE_CODE (val) != INTEGER_CST
|| tree_int_cst_sgn (val) < 0)
return false;
}
else
{
c_strlen_data lendata = { };
val = c_strlen (arg, 1, &lendata, eltsize);
if (!val && lendata.decl)
{
/* ARG refers to an unterminated const character array.
DATA.DECL with size DATA.LEN. */
val = lendata.minlen;
pdata->decl = lendata.decl;
}
}
/* Set if VAL represents the maximum length based on array size (set
when exact length cannot be determined). */
bool maxbound = false;
if (!val && rkind == SRK_LENRANGE)
{
if (TREE_CODE (arg) == ADDR_EXPR)
return get_range_strlen (TREE_OPERAND (arg, 0), visited, rkind,
pdata, eltsize);
if (TREE_CODE (arg) == ARRAY_REF)
{
tree optype = TREE_TYPE (TREE_OPERAND (arg, 0));
/* Determine the "innermost" array type. */
while (TREE_CODE (optype) == ARRAY_TYPE
&& TREE_CODE (TREE_TYPE (optype)) == ARRAY_TYPE)
optype = TREE_TYPE (optype);
/* Avoid arrays of pointers. */
tree eltype = TREE_TYPE (optype);
if (TREE_CODE (optype) != ARRAY_TYPE
|| !INTEGRAL_TYPE_P (eltype))
return false;
/* Fail when the array bound is unknown or zero. */
val = TYPE_SIZE_UNIT (optype);
if (!val
|| TREE_CODE (val) != INTEGER_CST
|| integer_zerop (val))
return false;
val = fold_build2 (MINUS_EXPR, TREE_TYPE (val), val,
integer_one_node);
/* Set the minimum size to zero since the string in
the array could have zero length. */
pdata->minlen = ssize_int (0);
tight_bound = true;
}
else if (TREE_CODE (arg) == COMPONENT_REF
&& (TREE_CODE (TREE_TYPE (TREE_OPERAND (arg, 1)))
== ARRAY_TYPE))
{
/* Use the type of the member array to determine the upper
bound on the length of the array. This may be overly
optimistic if the array itself isn't NUL-terminated and
the caller relies on the subsequent member to contain
the NUL but that would only be considered valid if
the array were the last member of a struct. */
tree fld = TREE_OPERAND (arg, 1);
tree optype = TREE_TYPE (fld);
/* Determine the "innermost" array type. */
while (TREE_CODE (optype) == ARRAY_TYPE
&& TREE_CODE (TREE_TYPE (optype)) == ARRAY_TYPE)
optype = TREE_TYPE (optype);
/* Fail when the array bound is unknown or zero. */
val = TYPE_SIZE_UNIT (optype);
if (!val
|| TREE_CODE (val) != INTEGER_CST
|| integer_zerop (val))
return false;
val = fold_build2 (MINUS_EXPR, TREE_TYPE (val), val,
integer_one_node);
/* Set the minimum size to zero since the string in
the array could have zero length. */
pdata->minlen = ssize_int (0);
/* The array size determined above is an optimistic bound
on the length. If the array isn't nul-terminated the
length computed by the library function would be greater.
Even though using strlen to cross the subobject boundary
is undefined, avoid drawing conclusions from the member
type about the length here. */
tight_bound = true;
}
else if (TREE_CODE (arg) == MEM_REF
&& TREE_CODE (TREE_TYPE (arg)) == ARRAY_TYPE
&& TREE_CODE (TREE_TYPE (TREE_TYPE (arg))) == INTEGER_TYPE
&& TREE_CODE (TREE_OPERAND (arg, 0)) == ADDR_EXPR)
{
/* Handle a MEM_REF into a DECL accessing an array of integers,
being conservative about references to extern structures with
flexible array members that can be initialized to arbitrary
numbers of elements as an extension (static structs are okay).
FIXME: Make this less conservative -- see
component_ref_size in tree.c. */
tree ref = TREE_OPERAND (TREE_OPERAND (arg, 0), 0);
if ((TREE_CODE (ref) == PARM_DECL || VAR_P (ref))
&& (decl_binds_to_current_def_p (ref)
|| !array_at_struct_end_p (arg)))
{
/* Fail if the offset is out of bounds. Such accesses
should be diagnosed at some point. */
val = DECL_SIZE_UNIT (ref);
if (!val
|| TREE_CODE (val) != INTEGER_CST
|| integer_zerop (val))
return false;
poly_offset_int psiz = wi::to_offset (val);
poly_offset_int poff = mem_ref_offset (arg);
if (known_le (psiz, poff))
return false;
pdata->minlen = ssize_int (0);
/* Subtract the offset and one for the terminating nul. */
psiz -= poff;
psiz -= 1;
val = wide_int_to_tree (TREE_TYPE (val), psiz);
/* Since VAL reflects the size of a declared object
rather the type of the access it is not a tight bound. */
}
}
else if (TREE_CODE (arg) == PARM_DECL || VAR_P (arg))
{
/* Avoid handling pointers to arrays. GCC might misuse
a pointer to an array of one bound to point to an array
object of a greater bound. */
tree argtype = TREE_TYPE (arg);
if (TREE_CODE (argtype) == ARRAY_TYPE)
{
val = TYPE_SIZE_UNIT (argtype);
if (!val
|| TREE_CODE (val) != INTEGER_CST
|| integer_zerop (val))
return false;
val = wide_int_to_tree (TREE_TYPE (val),
wi::sub (wi::to_wide (val), 1));
/* Set the minimum size to zero since the string in
the array could have zero length. */
pdata->minlen = ssize_int (0);
}
}
maxbound = true;
}
if (!val)
return false;
/* Adjust the lower bound on the string length as necessary. */
if (!pdata->minlen
|| (rkind != SRK_STRLEN
&& TREE_CODE (pdata->minlen) == INTEGER_CST
&& TREE_CODE (val) == INTEGER_CST
&& tree_int_cst_lt (val, pdata->minlen)))
pdata->minlen = val;
if (pdata->maxbound && TREE_CODE (pdata->maxbound) == INTEGER_CST)
{
/* Adjust the tighter (more optimistic) string length bound
if necessary and proceed to adjust the more conservative
bound. */
if (TREE_CODE (val) == INTEGER_CST)
{
if (tree_int_cst_lt (pdata->maxbound, val))
pdata->maxbound = val;
}
else
pdata->maxbound = val;
}
else if (pdata->maxbound || maxbound)
/* Set PDATA->MAXBOUND only if it either isn't INTEGER_CST or
if VAL corresponds to the maximum length determined based
on the type of the object. */
pdata->maxbound = val;
if (tight_bound)
{
/* VAL computed above represents an optimistically tight bound
on the length of the string based on the referenced object's
or subobject's type. Determine the conservative upper bound
based on the enclosing object's size if possible. */
if (rkind == SRK_LENRANGE)
{
poly_int64 offset;
tree base = get_addr_base_and_unit_offset (arg, &offset);
if (!base)
{
/* When the call above fails due to a non-constant offset
assume the offset is zero and use the size of the whole
enclosing object instead. */
base = get_base_address (arg);
offset = 0;
}
/* If the base object is a pointer no upper bound on the length
can be determined. Otherwise the maximum length is equal to
the size of the enclosing object minus the offset of
the referenced subobject minus 1 (for the terminating nul). */
tree type = TREE_TYPE (base);
if (TREE_CODE (type) == POINTER_TYPE
|| (TREE_CODE (base) != PARM_DECL && !VAR_P (base))
|| !(val = DECL_SIZE_UNIT (base)))
val = build_all_ones_cst (size_type_node);
else
{
val = DECL_SIZE_UNIT (base);
val = fold_build2 (MINUS_EXPR, TREE_TYPE (val), val,
size_int (offset + 1));
}
}
else
return false;
}
if (pdata->maxlen)
{
/* Adjust the more conservative bound if possible/necessary
and fail otherwise. */
if (rkind != SRK_STRLEN)
{
if (TREE_CODE (pdata->maxlen) != INTEGER_CST
|| TREE_CODE (val) != INTEGER_CST)
return false;
if (tree_int_cst_lt (pdata->maxlen, val))
pdata->maxlen = val;
return true;
}
else if (simple_cst_equal (val, pdata->maxlen) != 1)
{
/* Fail if the length of this ARG is different from that
previously determined from another ARG. */
return false;
}
}
pdata->maxlen = val;
return rkind == SRK_LENRANGE || !integer_all_onesp (val);
}
/* For an ARG referencing one or more strings, try to obtain the range
of their lengths, or the size of the largest array ARG referes to if
the range of lengths cannot be determined, and store all in *PDATA.
For an integer ARG (when RKIND == SRK_INT_VALUE), try to determine
the maximum constant value.
If ARG is an SSA_NAME, follow its use-def chains. When RKIND ==
SRK_STRLEN, then if PDATA->MAXLEN is not equal to the determined
length or if we are unable to determine the length, return false.
VISITED is a bitmap of visited variables.
RKIND determines the kind of value or range to obtain (see
strlen_range_kind).
Set PDATA->DECL if ARG refers to an unterminated constant array.
On input, set ELTSIZE to 1 for normal single byte character strings,
and either 2 or 4 for wide characer strings (the size of wchar_t).
Return true if *PDATA was successfully populated and false otherwise. */
static bool
get_range_strlen (tree arg, bitmap *visited,
strlen_range_kind rkind,
c_strlen_data *pdata, unsigned eltsize)
{
if (TREE_CODE (arg) != SSA_NAME)
return get_range_strlen_tree (arg, visited, rkind, pdata, eltsize);
/* If ARG is registered for SSA update we cannot look at its defining
statement. */
if (name_registered_for_update_p (arg))
return false;
/* If we were already here, break the infinite cycle. */
if (!*visited)
*visited = BITMAP_ALLOC (NULL);
if (!bitmap_set_bit (*visited, SSA_NAME_VERSION (arg)))
return true;
tree var = arg;
gimple *def_stmt = SSA_NAME_DEF_STMT (var);
switch (gimple_code (def_stmt))
{
case GIMPLE_ASSIGN:
/* The RHS of the statement defining VAR must either have a
constant length or come from another SSA_NAME with a constant
length. */
if (gimple_assign_single_p (def_stmt)
|| gimple_assign_unary_nop_p (def_stmt))
{
tree rhs = gimple_assign_rhs1 (def_stmt);
return get_range_strlen (rhs, visited, rkind, pdata, eltsize);
}
else if (gimple_assign_rhs_code (def_stmt) == COND_EXPR)
{
tree ops[2] = { gimple_assign_rhs2 (def_stmt),
gimple_assign_rhs3 (def_stmt) };
for (unsigned int i = 0; i < 2; i++)
if (!get_range_strlen (ops[i], visited, rkind, pdata, eltsize))
{
if (rkind != SRK_LENRANGE)
return false;
/* Set the upper bound to the maximum to prevent
it from being adjusted in the next iteration but
leave MINLEN and the more conservative MAXBOUND
determined so far alone (or leave them null if
they haven't been set yet). That the MINLEN is
in fact zero can be determined from MAXLEN being
unbounded but the discovered minimum is used for
diagnostics. */
pdata->maxlen = build_all_ones_cst (size_type_node);
}
return true;
}
return false;
case GIMPLE_PHI:
/* Unless RKIND == SRK_LENRANGE, all arguments of the PHI node
must have a constant length. */
for (unsigned i = 0; i < gimple_phi_num_args (def_stmt); i++)
{
tree arg = gimple_phi_arg (def_stmt, i)->def;
/* If this PHI has itself as an argument, we cannot
determine the string length of this argument. However,
if we can find a constant string length for the other
PHI args then we can still be sure that this is a
constant string length. So be optimistic and just
continue with the next argument. */
if (arg == gimple_phi_result (def_stmt))
continue;
if (!get_range_strlen (arg, visited, rkind, pdata, eltsize))
{
if (rkind != SRK_LENRANGE)
return false;
/* Set the upper bound to the maximum to prevent
it from being adjusted in the next iteration but
leave MINLEN and the more conservative MAXBOUND
determined so far alone (or leave them null if
they haven't been set yet). That the MINLEN is
in fact zero can be determined from MAXLEN being
unbounded but the discovered minimum is used for
diagnostics. */
pdata->maxlen = build_all_ones_cst (size_type_node);
}
}
return true;
default:
return false;
}
}
/* Try to obtain the range of the lengths of the string(s) referenced
by ARG, or the size of the largest array ARG refers to if the range
of lengths cannot be determined, and store all in *PDATA which must
be zero-initialized on input except PDATA->MAXBOUND may be set to
a non-null tree node other than INTEGER_CST to request to have it
set to the length of the longest string in a PHI. ELTSIZE is
the expected size of the string element in bytes: 1 for char and
some power of 2 for wide characters.
Return true if the range [PDATA->MINLEN, PDATA->MAXLEN] is suitable
for optimization. Returning false means that a nonzero PDATA->MINLEN
doesn't reflect the true lower bound of the range when PDATA->MAXLEN
is -1 (in that case, the actual range is indeterminate, i.e.,
[0, PTRDIFF_MAX - 2]. */
bool
get_range_strlen (tree arg, c_strlen_data *pdata, unsigned eltsize)
{
bitmap visited = NULL;
tree maxbound = pdata->maxbound;
if (!get_range_strlen (arg, &visited, SRK_LENRANGE, pdata, eltsize))
{
/* On failure extend the length range to an impossible maximum
(a valid MAXLEN must be less than PTRDIFF_MAX - 1). Other
members can stay unchanged regardless. */
pdata->minlen = ssize_int (0);
pdata->maxlen = build_all_ones_cst (size_type_node);
}
else if (!pdata->minlen)
pdata->minlen = ssize_int (0);
/* If it's unchanged from it initial non-null value, set the conservative
MAXBOUND to SIZE_MAX. Otherwise leave it null (if it is null). */
if (maxbound && pdata->maxbound == maxbound)
pdata->maxbound = build_all_ones_cst (size_type_node);
if (visited)
BITMAP_FREE (visited);
return !integer_all_onesp (pdata->maxlen);
}
/* Return the maximum value for ARG given RKIND (see strlen_range_kind).
For ARG of pointer types, NONSTR indicates if the caller is prepared
to handle unterminated strings. For integer ARG and when RKIND ==
SRK_INT_VALUE, NONSTR must be null.
If an unterminated array is discovered and our caller handles
unterminated arrays, then bubble up the offending DECL and
return the maximum size. Otherwise return NULL. */
static tree
get_maxval_strlen (tree arg, strlen_range_kind rkind, tree *nonstr = NULL)
{
/* A non-null NONSTR is meaningless when determining the maximum
value of an integer ARG. */
gcc_assert (rkind != SRK_INT_VALUE || nonstr == NULL);
/* ARG must have an integral type when RKIND says so. */
gcc_assert (rkind != SRK_INT_VALUE || INTEGRAL_TYPE_P (TREE_TYPE (arg)));
bitmap visited = NULL;
/* Reset DATA.MAXLEN if the call fails or when DATA.MAXLEN
is unbounded. */
c_strlen_data lendata = { };
if (!get_range_strlen (arg, &visited, rkind, &lendata, /* eltsize = */1))
lendata.maxlen = NULL_TREE;
else if (lendata.maxlen && integer_all_onesp (lendata.maxlen))
lendata.maxlen = NULL_TREE;
if (visited)
BITMAP_FREE (visited);
if (nonstr)
{
/* For callers prepared to handle unterminated arrays set
*NONSTR to point to the declaration of the array and return
the maximum length/size. */
*nonstr = lendata.decl;
return lendata.maxlen;
}
/* Fail if the constant array isn't nul-terminated. */
return lendata.decl ? NULL_TREE : lendata.maxlen;
}
/* Fold function call to builtin strcpy with arguments DEST and SRC.
If LEN is not NULL, it represents the length of the string to be
copied. Return NULL_TREE if no simplification can be made. */
static bool
gimple_fold_builtin_strcpy (gimple_stmt_iterator *gsi,
tree dest, tree src)
{
gimple *stmt = gsi_stmt (*gsi);
location_t loc = gimple_location (stmt);
tree fn;
/* If SRC and DEST are the same (and not volatile), return DEST. */
if (operand_equal_p (src, dest, 0))
{
/* Issue -Wrestrict unless the pointers are null (those do
not point to objects and so do not indicate an overlap;
such calls could be the result of sanitization and jump
threading). */
if (!integer_zerop (dest) && !warning_suppressed_p (stmt, OPT_Wrestrict))
{
tree func = gimple_call_fndecl (stmt);
warning_at (loc, OPT_Wrestrict,
"%qD source argument is the same as destination",
func);
}
replace_call_with_value (gsi, dest);
return true;
}
if (optimize_function_for_size_p (cfun))
return false;
fn = builtin_decl_implicit (BUILT_IN_MEMCPY);
if (!fn)
return false;
/* Set to non-null if ARG refers to an unterminated array. */
tree nonstr = NULL;
tree len = get_maxval_strlen (src, SRK_STRLEN, &nonstr);
if (nonstr)
{
/* Avoid folding calls with unterminated arrays. */
if (!warning_suppressed_p (stmt, OPT_Wstringop_overread))
warn_string_no_nul (loc, stmt, "strcpy", src, nonstr);
suppress_warning (stmt, OPT_Wstringop_overread);
return false;
}
if (!len)
return false;
len = fold_convert_loc (loc, size_type_node, len);
len = size_binop_loc (loc, PLUS_EXPR, len, build_int_cst (size_type_node, 1));
len = force_gimple_operand_gsi (gsi, len, true,
NULL_TREE, true, GSI_SAME_STMT);
gimple *repl = gimple_build_call (fn, 3, dest, src, len);
replace_call_with_call_and_fold (gsi, repl);
return true;
}
/* Fold function call to builtin strncpy with arguments DEST, SRC, and LEN.
If SLEN is not NULL, it represents the length of the source string.
Return NULL_TREE if no simplification can be made. */
static bool
gimple_fold_builtin_strncpy (gimple_stmt_iterator *gsi,
tree dest, tree src, tree len)
{
gimple *stmt = gsi_stmt (*gsi);
location_t loc = gimple_location (stmt);
bool nonstring = get_attr_nonstring_decl (dest) != NULL_TREE;
/* If the LEN parameter is zero, return DEST. */
if (integer_zerop (len))
{
/* Avoid warning if the destination refers to an array/pointer
decorate with attribute nonstring. */
if (!nonstring)
{
tree fndecl = gimple_call_fndecl (stmt);
/* Warn about the lack of nul termination: the result is not
a (nul-terminated) string. */
tree slen = get_maxval_strlen (src, SRK_STRLEN);
if (slen && !integer_zerop (slen))
warning_at (loc, OPT_Wstringop_truncation,
"%qD destination unchanged after copying no bytes "
"from a string of length %E",
fndecl, slen);
else
warning_at (loc, OPT_Wstringop_truncation,
"%qD destination unchanged after copying no bytes",
fndecl);
}
replace_call_with_value (gsi, dest);
return true;
}
/* We can't compare slen with len as constants below if len is not a
constant. */
if (TREE_CODE (len) != INTEGER_CST)
return false;
/* Now, we must be passed a constant src ptr parameter. */
tree slen = get_maxval_strlen (src, SRK_STRLEN);
if (!slen || TREE_CODE (slen) != INTEGER_CST)
return false;
/* The size of the source string including the terminating nul. */
tree ssize = size_binop_loc (loc, PLUS_EXPR, slen, ssize_int (1));
/* We do not support simplification of this case, though we do
support it when expanding trees into RTL. */
/* FIXME: generate a call to __builtin_memset. */
if (tree_int_cst_lt (ssize, len))
return false;
/* Diagnose truncation that leaves the copy unterminated. */
maybe_diag_stxncpy_trunc (*gsi, src, len);
/* OK transform into builtin memcpy. */
tree fn = builtin_decl_implicit (BUILT_IN_MEMCPY);
if (!fn)
return false;
len = fold_convert_loc (loc, size_type_node, len);
len = force_gimple_operand_gsi (gsi, len, true,
NULL_TREE, true, GSI_SAME_STMT);
gimple *repl = gimple_build_call (fn, 3, dest, src, len);
replace_call_with_call_and_fold (gsi, repl);
return true;
}
/* Fold function call to builtin strchr or strrchr.
If both arguments are constant, evaluate and fold the result,
otherwise simplify str(r)chr (str, 0) into str + strlen (str).
In general strlen is significantly faster than strchr
due to being a simpler operation. */
static bool
gimple_fold_builtin_strchr (gimple_stmt_iterator *gsi, bool is_strrchr)
{
gimple *stmt = gsi_stmt (*gsi);
tree str = gimple_call_arg (stmt, 0);
tree c = gimple_call_arg (stmt, 1);
location_t loc = gimple_location (stmt);
const char *p;
char ch;
if (!gimple_call_lhs (stmt))
return false;
/* Avoid folding if the first argument is not a nul-terminated array.
Defer warning until later. */
if (!check_nul_terminated_array (NULL_TREE, str))
return false;
if ((p = c_getstr (str)) && target_char_cst_p (c, &ch))
{
const char *p1 = is_strrchr ? strrchr (p, ch) : strchr (p, ch);
if (p1 == NULL)
{
replace_call_with_value (gsi, integer_zero_node);
return true;
}
tree len = build_int_cst (size_type_node, p1 - p);
gimple_seq stmts = NULL;
gimple *new_stmt = gimple_build_assign (gimple_call_lhs (stmt),
POINTER_PLUS_EXPR, str, len);
gimple_seq_add_stmt_without_update (&stmts, new_stmt);
gsi_replace_with_seq_vops (gsi, stmts);
return true;
}
if (!integer_zerop (c))
return false;
/* Transform strrchr (s, 0) to strchr (s, 0) when optimizing for size. */
if (is_strrchr && optimize_function_for_size_p (cfun))
{
tree strchr_fn = builtin_decl_implicit (BUILT_IN_STRCHR);
if (strchr_fn)
{
gimple *repl = gimple_build_call (strchr_fn, 2, str, c);
replace_call_with_call_and_fold (gsi, repl);
return true;
}
return false;
}
tree len;
tree strlen_fn = builtin_decl_implicit (BUILT_IN_STRLEN);
if (!strlen_fn)
return false;
/* Create newstr = strlen (str). */
gimple_seq stmts = NULL;
gimple *new_stmt = gimple_build_call (strlen_fn, 1, str);
gimple_set_location (new_stmt, loc);
len = create_tmp_reg_or_ssa_name (size_type_node);
gimple_call_set_lhs (new_stmt, len);
gimple_seq_add_stmt_without_update (&stmts, new_stmt);
/* Create (str p+ strlen (str)). */
new_stmt = gimple_build_assign (gimple_call_lhs (stmt),
POINTER_PLUS_EXPR, str, len);
gimple_seq_add_stmt_without_update (&stmts, new_stmt);
gsi_replace_with_seq_vops (gsi, stmts);
/* gsi now points at the assignment to the lhs, get a
stmt iterator to the strlen.
??? We can't use gsi_for_stmt as that doesn't work when the
CFG isn't built yet. */
gimple_stmt_iterator gsi2 = *gsi;
gsi_prev (&gsi2);
fold_stmt (&gsi2);
return true;
}
/* Fold function call to builtin strstr.
If both arguments are constant, evaluate and fold the result,
additionally fold strstr (x, "") into x and strstr (x, "c")
into strchr (x, 'c'). */
static bool
gimple_fold_builtin_strstr (gimple_stmt_iterator *gsi)
{
gimple *stmt = gsi_stmt (*gsi);
if (!gimple_call_lhs (stmt))
return false;
tree haystack = gimple_call_arg (stmt, 0);
tree needle = gimple_call_arg (stmt, 1);
/* Avoid folding if either argument is not a nul-terminated array.
Defer warning until later. */
if (!check_nul_terminated_array (NULL_TREE, haystack)
|| !check_nul_terminated_array (NULL_TREE, needle))
return false;
const char *q = c_getstr (needle);
if (q == NULL)
return false;
if (const char *p = c_getstr (haystack))
{
const char *r = strstr (p, q);
if (r == NULL)
{
replace_call_with_value (gsi, integer_zero_node);
return true;
}
tree len = build_int_cst (size_type_node, r - p);
gimple_seq stmts = NULL;
gimple *new_stmt
= gimple_build_assign (gimple_call_lhs (stmt), POINTER_PLUS_EXPR,
haystack, len);
gimple_seq_add_stmt_without_update (&stmts, new_stmt);
gsi_replace_with_seq_vops (gsi, stmts);
return true;
}
/* For strstr (x, "") return x. */
if (q[0] == '\0')
{
replace_call_with_value (gsi, haystack);
return true;
}
/* Transform strstr (x, "c") into strchr (x, 'c'). */
if (q[1] == '\0')
{
tree strchr_fn = builtin_decl_implicit (BUILT_IN_STRCHR);
if (strchr_fn)
{
tree c = build_int_cst (integer_type_node, q[0]);
gimple *repl = gimple_build_call (strchr_fn, 2, haystack, c);
replace_call_with_call_and_fold (gsi, repl);
return true;
}
}
return false;
}
/* Simplify a call to the strcat builtin. DST and SRC are the arguments
to the call.
Return NULL_TREE if no simplification was possible, otherwise return the
simplified form of the call as a tree.
The simplified form may be a constant or other expression which
computes the same value, but in a more efficient manner (including
calls to other builtin functions).
The call may contain arguments which need to be evaluated, but
which are not useful to determine the result of the call. In
this case we return a chain of COMPOUND_EXPRs. The LHS of each
COMPOUND_EXPR will be an argument which must be evaluated.
COMPOUND_EXPRs are chained through their RHS. The RHS of the last
COMPOUND_EXPR in the chain will contain the tree for the simplified
form of the builtin function call. */
static bool
gimple_fold_builtin_strcat (gimple_stmt_iterator *gsi, tree dst, tree src)
{
gimple *stmt = gsi_stmt (*gsi);
location_t loc = gimple_location (stmt);
const char *p = c_getstr (src);
/* If the string length is zero, return the dst parameter. */
if (p && *p == '\0')
{
replace_call_with_value (gsi, dst);
return true;
}
if (!optimize_bb_for_speed_p (gimple_bb (stmt)))
return false;
/* See if we can store by pieces into (dst + strlen(dst)). */
tree newdst;
tree strlen_fn = builtin_decl_implicit (BUILT_IN_STRLEN);
tree memcpy_fn = builtin_decl_implicit (BUILT_IN_MEMCPY);
if (!strlen_fn || !memcpy_fn)
return false;
/* If the length of the source string isn't computable don't
split strcat into strlen and memcpy. */
tree len = get_maxval_strlen (src, SRK_STRLEN);
if (! len)
return false;
/* Create strlen (dst). */
gimple_seq stmts = NULL, stmts2;
gimple *repl = gimple_build_call (strlen_fn, 1, dst);
gimple_set_location (repl, loc);
newdst = create_tmp_reg_or_ssa_name (size_type_node);
gimple_call_set_lhs (repl, newdst);
gimple_seq_add_stmt_without_update (&stmts, repl);
/* Create (dst p+ strlen (dst)). */
newdst = fold_build_pointer_plus_loc (loc, dst, newdst);
newdst = force_gimple_operand (newdst, &stmts2, true, NULL_TREE);
gimple_seq_add_seq_without_update (&stmts, stmts2);
len = fold_convert_loc (loc, size_type_node, len);
len = size_binop_loc (loc, PLUS_EXPR, len,
build_int_cst (size_type_node, 1));
len = force_gimple_operand (len, &stmts2, true, NULL_TREE);
gimple_seq_add_seq_without_update (&stmts, stmts2);
repl = gimple_build_call (memcpy_fn, 3, newdst, src, len);
gimple_seq_add_stmt_without_update (&stmts, repl);
if (gimple_call_lhs (stmt))
{
repl = gimple_build_assign (gimple_call_lhs (stmt), dst);
gimple_seq_add_stmt_without_update (&stmts, repl);
gsi_replace_with_seq_vops (gsi, stmts);
/* gsi now points at the assignment to the lhs, get a
stmt iterator to the memcpy call.
??? We can't use gsi_for_stmt as that doesn't work when the
CFG isn't built yet. */
gimple_stmt_iterator gsi2 = *gsi;
gsi_prev (&gsi2);
fold_stmt (&gsi2);
}
else
{
gsi_replace_with_seq_vops (gsi, stmts);
fold_stmt (gsi);
}
return true;
}
/* Fold a call to the __strcat_chk builtin FNDECL. DEST, SRC, and SIZE
are the arguments to the call. */
static bool
gimple_fold_builtin_strcat_chk (gimple_stmt_iterator *gsi)
{
gimple *stmt = gsi_stmt (*gsi);
tree dest = gimple_call_arg (stmt, 0);
tree src = gimple_call_arg (stmt, 1);
tree size = gimple_call_arg (stmt, 2);
tree fn;
const char *p;
p = c_getstr (src);
/* If the SRC parameter is "", return DEST. */
if (p && *p == '\0')
{
replace_call_with_value (gsi, dest);
return true;
}
if (! tree_fits_uhwi_p (size) || ! integer_all_onesp (size))
return false;
/* If __builtin_strcat_chk is used, assume strcat is available. */
fn = builtin_decl_explicit (BUILT_IN_STRCAT);
if (!fn)
return false;
gimple *repl = gimple_build_call (fn, 2, dest, src);
replace_call_with_call_and_fold (gsi, repl);
return true;
}
/* Simplify a call to the strncat builtin. */
static bool
gimple_fold_builtin_strncat (gimple_stmt_iterator *gsi)
{
gimple *stmt = gsi_stmt (*gsi);
tree dst = gimple_call_arg (stmt, 0);
tree src = gimple_call_arg (stmt, 1);
tree len = gimple_call_arg (stmt, 2);
const char *p = c_getstr (src);
/* If the requested length is zero, or the src parameter string
length is zero, return the dst parameter. */
if (integer_zerop (len) || (p && *p == '\0'))
{
replace_call_with_value (gsi, dst);
return true;
}
if (TREE_CODE (len) != INTEGER_CST || !p)
return false;
unsigned srclen = strlen (p);
int cmpsrc = compare_tree_int (len, srclen);
/* Return early if the requested len is less than the string length.
Warnings will be issued elsewhere later. */
if (cmpsrc < 0)
return false;
unsigned HOST_WIDE_INT dstsize;
bool nowarn = warning_suppressed_p (stmt, OPT_Wstringop_overflow_);
if (!nowarn && compute_builtin_object_size (dst, 1, &dstsize))
{
int cmpdst = compare_tree_int (len, dstsize);
if (cmpdst >= 0)
{
tree fndecl = gimple_call_fndecl (stmt);
/* Strncat copies (at most) LEN bytes and always appends
the terminating NUL so the specified bound should never
be equal to (or greater than) the size of the destination.
If it is, the copy could overflow. */
location_t loc = gimple_location (stmt);
nowarn = warning_at (loc, OPT_Wstringop_overflow_,
cmpdst == 0
? G_("%qD specified bound %E equals "
"destination size")
: G_("%qD specified bound %E exceeds "
"destination size %wu"),
fndecl, len, dstsize);
if (nowarn)
suppress_warning (stmt, OPT_Wstringop_overflow_);
}
}
if (!nowarn && cmpsrc == 0)
{
tree fndecl = gimple_call_fndecl (stmt);
location_t loc = gimple_location (stmt);
/* To avoid possible overflow the specified bound should also
not be equal to the length of the source, even when the size
of the destination is unknown (it's not an uncommon mistake
to specify as the bound to strncpy the length of the source). */
if (warning_at (loc, OPT_Wstringop_overflow_,
"%qD specified bound %E equals source length",
fndecl, len))
suppress_warning (stmt, OPT_Wstringop_overflow_);
}
tree fn = builtin_decl_implicit (BUILT_IN_STRCAT);
/* If the replacement _DECL isn't initialized, don't do the
transformation. */
if (!fn)
return false;
/* Otherwise, emit a call to strcat. */
gcall *repl = gimple_build_call (fn, 2, dst, src);
replace_call_with_call_and_fold (gsi, repl);
return true;
}
/* Fold a call to the __strncat_chk builtin with arguments DEST, SRC,
LEN, and SIZE. */
static bool
gimple_fold_builtin_strncat_chk (gimple_stmt_iterator *gsi)
{
gimple *stmt = gsi_stmt (*gsi);
tree dest = gimple_call_arg (stmt, 0);
tree src = gimple_call_arg (stmt, 1);
tree len = gimple_call_arg (stmt, 2);
tree size = gimple_call_arg (stmt, 3);
tree fn;
const char *p;
p = c_getstr (src);
/* If the SRC parameter is "" or if LEN is 0, return DEST. */
if ((p && *p == '\0')
|| integer_zerop (len))
{
replace_call_with_value (gsi, dest);
return true;
}
if (! tree_fits_uhwi_p (size))
return false;
if (! integer_all_onesp (size))
{
tree src_len = c_strlen (src, 1);
if (src_len
&& tree_fits_uhwi_p (src_len)
&& tree_fits_uhwi_p (len)
&& ! tree_int_cst_lt (len, src_len))
{
/* If LEN >= strlen (SRC), optimize into __strcat_chk. */
fn = builtin_decl_explicit (BUILT_IN_STRCAT_CHK);
if (!fn)
return false;
gimple *repl = gimple_build_call (fn, 3, dest, src, size);
replace_call_with_call_and_fold (gsi, repl);
return true;
}
return false;
}
/* If __builtin_strncat_chk is used, assume strncat is available. */
fn = builtin_decl_explicit (BUILT_IN_STRNCAT);
if (!fn)
return false;
gimple *repl = gimple_build_call (fn, 3, dest, src, len);
replace_call_with_call_and_fold (gsi, repl);
return true;
}
/* Build and append gimple statements to STMTS that would load a first
character of a memory location identified by STR. LOC is location
of the statement. */
static tree
gimple_load_first_char (location_t loc, tree str, gimple_seq *stmts)
{
tree var;
tree cst_uchar_node = build_type_variant (unsigned_char_type_node, 1, 0);
tree cst_uchar_ptr_node
= build_pointer_type_for_mode (cst_uchar_node, ptr_mode, true);
tree off0 = build_int_cst (cst_uchar_ptr_node, 0);
tree temp = fold_build2_loc (loc, MEM_REF, cst_uchar_node, str, off0);
gassign *stmt = gimple_build_assign (NULL_TREE, temp);
var = create_tmp_reg_or_ssa_name (cst_uchar_node, stmt);
gimple_assign_set_lhs (stmt, var);
gimple_seq_add_stmt_without_update (stmts, stmt);
return var;
}
/* Fold a call to the str{n}{case}cmp builtin pointed by GSI iterator. */
static bool
gimple_fold_builtin_string_compare (gimple_stmt_iterator *gsi)
{
gimple *stmt = gsi_stmt (*gsi);
tree callee = gimple_call_fndecl (stmt);
enum built_in_function fcode = DECL_FUNCTION_CODE (callee);
tree type = integer_type_node;
tree str1 = gimple_call_arg (stmt, 0);
tree str2 = gimple_call_arg (stmt, 1);
tree lhs = gimple_call_lhs (stmt);
tree bound_node = NULL_TREE;
unsigned HOST_WIDE_INT bound = HOST_WIDE_INT_M1U;
/* Handle strncmp and strncasecmp functions. */
if (gimple_call_num_args (stmt) == 3)
{
bound_node = gimple_call_arg (stmt, 2);
if (tree_fits_uhwi_p (bound_node))
bound = tree_to_uhwi (bound_node);
}
/* If the BOUND parameter is zero, return zero. */
if (bound == 0)
{
replace_call_with_value (gsi, integer_zero_node);
return true;
}
/* If ARG1 and ARG2 are the same (and not volatile), return zero. */
if (operand_equal_p (str1, str2, 0))
{
replace_call_with_value (gsi, integer_zero_node);
return true;
}
/* Initially set to the number of characters, including the terminating
nul if each array has one. LENx == strnlen (Sx, LENx) implies that
the array Sx is not terminated by a nul.
For nul-terminated strings then adjusted to their length so that
LENx == NULPOSx holds. */
unsigned HOST_WIDE_INT len1 = HOST_WIDE_INT_MAX, len2 = len1;
const char *p1 = getbyterep (str1, &len1);
const char *p2 = getbyterep (str2, &len2);
/* The position of the terminating nul character if one exists, otherwise
a value greater than LENx. */
unsigned HOST_WIDE_INT nulpos1 = HOST_WIDE_INT_MAX, nulpos2 = nulpos1;
if (p1)
{
size_t n = strnlen (p1, len1);
if (n < len1)
len1 = nulpos1 = n;
}
if (p2)
{
size_t n = strnlen (p2, len2);
if (n < len2)
len2 = nulpos2 = n;
}
/* For known strings, return an immediate value. */
if (p1 && p2)
{
int r = 0;
bool known_result = false;
switch (fcode)
{
case BUILT_IN_STRCMP:
case BUILT_IN_STRCMP_EQ:
if (len1 != nulpos1 || len2 != nulpos2)
break;
r = strcmp (p1, p2);
known_result = true;
break;
case BUILT_IN_STRNCMP:
case BUILT_IN_STRNCMP_EQ:
{
if (bound == HOST_WIDE_INT_M1U)
break;
/* Reduce the bound to be no more than the length
of the shorter of the two strings, or the sizes
of the unterminated arrays. */
unsigned HOST_WIDE_INT n = bound;
if (len1 == nulpos1 && len1 < n)
n = len1 + 1;
if (len2 == nulpos2 && len2 < n)
n = len2 + 1;
if (MIN (nulpos1, nulpos2) + 1 < n)
break;
r = strncmp (p1, p2, n);
known_result = true;
break;
}
/* Only handleable situation is where the string are equal (result 0),
which is already handled by operand_equal_p case. */
case BUILT_IN_STRCASECMP:
break;
case BUILT_IN_STRNCASECMP:
{
if (bound == HOST_WIDE_INT_M1U)
break;
r = strncmp (p1, p2, bound);
if (r == 0)
known_result = true;
break;
}
default:
gcc_unreachable ();
}
if (known_result)
{
replace_call_with_value (gsi, build_cmp_result (type, r));
return true;
}
}
bool nonzero_bound = (bound >= 1 && bound < HOST_WIDE_INT_M1U)
|| fcode == BUILT_IN_STRCMP
|| fcode == BUILT_IN_STRCMP_EQ
|| fcode == BUILT_IN_STRCASECMP;
location_t loc = gimple_location (stmt);
/* If the second arg is "", return *(const unsigned char*)arg1. */
if (p2 && *p2 == '\0' && nonzero_bound)
{
gimple_seq stmts = NULL;
tree var = gimple_load_first_char (loc, str1, &stmts);
if (lhs)
{
stmt = gimple_build_assign (lhs, NOP_EXPR, var);
gimple_seq_add_stmt_without_update (&stmts, stmt);
}
gsi_replace_with_seq_vops (gsi, stmts);
return true;
}
/* If the first arg is "", return -*(const unsigned char*)arg2. */
if (p1 && *p1 == '\0' && nonzero_bound)
{
gimple_seq stmts = NULL;
tree var = gimple_load_first_char (loc, str2, &stmts);
if (lhs)
{
tree c = create_tmp_reg_or_ssa_name (integer_type_node);
stmt = gimple_build_assign (c, NOP_EXPR, var);
gimple_seq_add_stmt_without_update (&stmts, stmt);
stmt = gimple_build_assign (lhs, NEGATE_EXPR, c);
gimple_seq_add_stmt_without_update (&stmts, stmt);
}
gsi_replace_with_seq_vops (gsi, stmts);
return true;
}
/* If BOUND is one, return an expression corresponding to
(*(const unsigned char*)arg2 - *(const unsigned char*)arg1). */
if (fcode == BUILT_IN_STRNCMP && bound == 1)
{
gimple_seq stmts = NULL;
tree temp1 = gimple_load_first_char (loc, str1, &stmts);
tree temp2 = gimple_load_first_char (loc, str2, &stmts);
if (lhs)
{
tree c1 = create_tmp_reg_or_ssa_name (integer_type_node);
gassign *convert1 = gimple_build_assign (c1, NOP_EXPR, temp1);
gimple_seq_add_stmt_without_update (&stmts, convert1);
tree c2 = create_tmp_reg_or_ssa_name (integer_type_node);
gassign *convert2 = gimple_build_assign (c2, NOP_EXPR, temp2);
gimple_seq_add_stmt_without_update (&stmts, convert2);
stmt = gimple_build_assign (lhs, MINUS_EXPR, c1, c2);
gimple_seq_add_stmt_without_update (&stmts, stmt);
}
gsi_replace_with_seq_vops <