/* Convert language-specific tree expression to rtl instructions,
for GNU compiler.
Copyright (C) 1988-2020 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
GCC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "cp-tree.h"
/* Expand C++-specific constants. Currently, this means PTRMEM_CST. */
tree
cplus_expand_constant (tree cst)
{
switch (TREE_CODE (cst))
{
case PTRMEM_CST:
{
tree type = TREE_TYPE (cst);
tree member;
/* Find the member. */
member = PTRMEM_CST_MEMBER (cst);
/* We can't lower this until the class is complete. */
if (!COMPLETE_TYPE_P (DECL_CONTEXT (member)))
return cst;
if (TREE_CODE (member) == FIELD_DECL)
{
/* Find the offset for the field. */
cst = byte_position (member);
while (!same_type_p (DECL_CONTEXT (member),
TYPE_PTRMEM_CLASS_TYPE (type)))
{
/* The MEMBER must have been nestled within an
anonymous aggregate contained in TYPE. Find the
anonymous aggregate. */
member = lookup_anon_field (TYPE_PTRMEM_CLASS_TYPE (type),
DECL_CONTEXT (member));
cst = size_binop (PLUS_EXPR, cst, byte_position (member));
}
cst = fold (build_nop (type, cst));
}
else
{
tree delta;
tree pfn;
expand_ptrmemfunc_cst (cst, &delta, &pfn);
cst = build_ptrmemfunc1 (type, delta, pfn);
}
}
break;
case CONSTRUCTOR:
{
constructor_elt *elt;
unsigned HOST_WIDE_INT idx;
FOR_EACH_VEC_SAFE_ELT (CONSTRUCTOR_ELTS (cst), idx, elt)
elt->value = cplus_expand_constant (elt->value);
}
default:
/* There's nothing to do. */
break;
}
return cst;
}
/* We've seen an actual use of EXPR. Possibly replace an outer variable
reference inside with its constant value or a lambda capture. */
tree
mark_use (tree expr, bool rvalue_p, bool read_p,
location_t loc /* = UNKNOWN_LOCATION */,
bool reject_builtin /* = true */)
{
#define RECUR(t) mark_use ((t), rvalue_p, read_p, loc, reject_builtin)
if (expr == NULL_TREE || error_operand_p (expr))
return expr;
if (reject_builtin && reject_gcc_builtin (expr, loc))
return error_mark_node;
if (read_p)
mark_exp_read (expr);
tree oexpr = expr;
bool recurse_op[3] = { false, false, false };
switch (TREE_CODE (expr))
{
case VAR_DECL:
case PARM_DECL:
if (rvalue_p && is_normal_capture_proxy (expr))
{
/* Look through capture by copy. */
tree cap = DECL_CAPTURED_VARIABLE (expr);
if (TREE_CODE (TREE_TYPE (cap)) == TREE_CODE (TREE_TYPE (expr))
&& decl_constant_var_p (cap))
{
tree val = RECUR (cap);
if (!is_capture_proxy (val))
{
tree l = current_lambda_expr ();
LAMBDA_EXPR_CAPTURE_OPTIMIZED (l) = true;
}
return val;
}
}
if (outer_automatic_var_p (expr)
&& decl_constant_var_p (expr))
{
if (rvalue_p)
{
tree t = maybe_constant_value (expr);
if (TREE_CONSTANT (t))
{
expr = t;
break;
}
}
temp_override<location_t> l (input_location);
if (loc != UNKNOWN_LOCATION)
input_location = loc;
expr = process_outer_var_ref (expr, tf_warning_or_error, true);
if (!(TREE_TYPE (oexpr)
&& TYPE_REF_P (TREE_TYPE (oexpr))))
expr = convert_from_reference (expr);
}
break;
case COMPONENT_REF:
case NON_DEPENDENT_EXPR:
recurse_op[0] = true;
break;
case COMPOUND_EXPR:
recurse_op[1] = true;
break;
case COND_EXPR:
recurse_op[2] = true;
if (TREE_OPERAND (expr, 1))
recurse_op[1] = true;
break;
case INDIRECT_REF:
if (REFERENCE_REF_P (expr))
{
/* Try to look through the reference. */
tree ref = TREE_OPERAND (expr, 0);
if (rvalue_p && is_normal_capture_proxy (ref))
{
/* Look through capture by reference. */
tree cap = DECL_CAPTURED_VARIABLE (ref);
if (!TYPE_REF_P (TREE_TYPE (cap))
&& decl_constant_var_p (cap))
{
tree val = RECUR (cap);
if (!is_capture_proxy (val))
{
tree l = current_lambda_expr ();
LAMBDA_EXPR_CAPTURE_OPTIMIZED (l) = true;
}
return val;
}
}
tree r = mark_rvalue_use (ref, loc, reject_builtin);
if (r != ref)
expr = convert_from_reference (r);
}
break;
case VIEW_CONVERT_EXPR:
if (location_wrapper_p (expr))
{
loc = EXPR_LOCATION (expr);
tree op = TREE_OPERAND (expr, 0);
tree nop = RECUR (op);
if (nop == error_mark_node)
return error_mark_node;
else if (op == nop)
/* No change. */;
else if (DECL_P (nop) || CONSTANT_CLASS_P (nop))
{
/* Reuse the location wrapper. */
TREE_OPERAND (expr, 0) = nop;
/* If we're replacing a DECL with a constant, we also need to
change the TREE_CODE of the location wrapper. */
if (rvalue_p)
TREE_SET_CODE (expr, NON_LVALUE_EXPR);
}
else
{
/* Drop the location wrapper. */
expr = nop;
protected_set_expr_location (expr, loc);
}
return expr;
}
gcc_fallthrough();
CASE_CONVERT:
recurse_op[0] = true;
break;
case MODIFY_EXPR:
{
tree lhs = TREE_OPERAND (expr, 0);
/* [expr.ass] "A simple assignment whose left operand is of
a volatile-qualified type is deprecated unless the assignment
is either a discarded-value expression or appears in an
unevaluated context." */
if (!cp_unevaluated_operand
&& (TREE_THIS_VOLATILE (lhs)
|| CP_TYPE_VOLATILE_P (TREE_TYPE (lhs)))
&& !TREE_THIS_VOLATILE (expr))
{
if (warning_at (location_of (expr), OPT_Wvolatile,
"using value of simple assignment with "
"%<volatile%>-qualified left operand is "
"deprecated"))
/* Make sure not to warn about this assignment again. */
TREE_THIS_VOLATILE (expr) = true;
}
break;
}
default:
break;
}
for (int i = 0; i < 3; ++i)
if (recurse_op[i])
{
tree op = TREE_OPERAND (expr, i);
op = RECUR (op);
if (op == error_mark_node)
return error_mark_node;
TREE_OPERAND (expr, i) = op;
}
return expr;
#undef RECUR
}
/* Called whenever the expression EXPR is used in an rvalue context.
When REJECT_BUILTIN is true the expression is checked to make sure
it doesn't make it possible to obtain the address of a GCC built-in
function with no library fallback (or any of its bits, such as in
a conversion to bool). */
tree
mark_rvalue_use (tree e,
location_t loc /* = UNKNOWN_LOCATION */,
bool reject_builtin /* = true */)
{
return mark_use (e, true, true, loc, reject_builtin);
}
/* Called whenever an expression is used in an lvalue context. */
tree
mark_lvalue_use (tree expr)
{
return mark_use (expr, false, true, input_location, false);
}
/* As above, but don't consider this use a read. */
tree
mark_lvalue_use_nonread (tree expr)
{
return mark_use (expr, false, false, input_location, false);
}
/* Called when expr appears as a discarded-value expression. */
tree
mark_discarded_use (tree expr)
{
/* The lvalue-to-rvalue conversion (7.1) is applied if and only if the
expression is a glvalue of volatile-qualified type and it is one of the
following:
* ( expression ), where expression is one of these expressions,
* id-expression (8.1.4),
* subscripting (8.2.1),
* class member access (8.2.5),
* indirection (8.3.1),
* pointer-to-member operation (8.5),
* conditional expression (8.16) where both the second and the third
operands are one of these expressions, or
* comma expression (8.19) where the right operand is one of these
expressions. */
if (expr == NULL_TREE)
return expr;
STRIP_ANY_LOCATION_WRAPPER (expr);
switch (TREE_CODE (expr))
{
case COND_EXPR:
TREE_OPERAND (expr, 2) = mark_discarded_use (TREE_OPERAND (expr, 2));
gcc_fallthrough ();
case COMPOUND_EXPR:
TREE_OPERAND (expr, 1) = mark_discarded_use (TREE_OPERAND (expr, 1));
return expr;
case COMPONENT_REF:
case ARRAY_REF:
case INDIRECT_REF:
case MEMBER_REF:
break;
default:
if (DECL_P (expr))
break;
else
return expr;
}
/* Like mark_rvalue_use, but don't reject built-ins. */
return mark_use (expr, true, true, input_location, false);
}
/* Called whenever an expression is used in a type use context. */
tree
mark_type_use (tree expr)
{
mark_exp_read (expr);
return expr;
}
/* Mark EXP as read, not just set, for set but not used -Wunused
warning purposes. */
void
mark_exp_read (tree exp)
{
if (exp == NULL)
return;
switch (TREE_CODE (exp))
{
case VAR_DECL:
if (DECL_DECOMPOSITION_P (exp))
mark_exp_read (DECL_DECOMP_BASE (exp));
gcc_fallthrough ();
case PARM_DECL:
DECL_READ_P (exp) = 1;
break;
case ARRAY_REF:
case COMPONENT_REF:
case MODIFY_EXPR:
case REALPART_EXPR:
case IMAGPART_EXPR:
CASE_CONVERT:
case ADDR_EXPR:
case INDIRECT_REF:
case FLOAT_EXPR:
case NON_DEPENDENT_EXPR:
case VIEW_CONVERT_EXPR:
mark_exp_read (TREE_OPERAND (exp, 0));
break;
case COMPOUND_EXPR:
mark_exp_read (TREE_OPERAND (exp, 1));
break;
case COND_EXPR:
if (TREE_OPERAND (exp, 1))
mark_exp_read (TREE_OPERAND (exp, 1));
if (TREE_OPERAND (exp, 2))
mark_exp_read (TREE_OPERAND (exp, 2));
break;
default:
break;
}
}
/* Fold X for consideration by one of the warning functions when checking
whether an expression has a constant value. */
tree
fold_for_warn (tree x)
{
/* C++ implementation. */
/* It's not generally safe to fully fold inside of a template, so
call fold_non_dependent_expr instead. */
if (processing_template_decl)
{
tree f = fold_non_dependent_expr (x, tf_none);
if (f == error_mark_node)
return x;
else
return f;
}
else if (cxx_dialect >= cxx11)
x = maybe_constant_value (x, NULL_TREE, false, true);
return c_fully_fold (x, /*for_init*/false, /*maybe_constp*/NULL);
}