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