953 lines
29 KiB
C
953 lines
29 KiB
C
/* GIMPLE lowering pass. Converts High GIMPLE into Low GIMPLE.
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Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
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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 it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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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 "tm.h"
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#include "tree.h"
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#include "gimple.h"
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#include "tree-iterator.h"
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#include "tree-inline.h"
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#include "tree-flow.h"
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#include "flags.h"
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#include "function.h"
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#include "diagnostic-core.h"
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#include "tree-pass.h"
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/* The differences between High GIMPLE and Low GIMPLE are the
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following:
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1- Lexical scopes are removed (i.e., GIMPLE_BIND disappears).
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2- GIMPLE_TRY and GIMPLE_CATCH are converted to abnormal control
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flow and exception regions are built as an on-the-side region
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hierarchy (See tree-eh.c:lower_eh_constructs).
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3- Multiple identical return statements are grouped into a single
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return and gotos to the unique return site. */
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/* Match a return statement with a label. During lowering, we identify
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identical return statements and replace duplicates with a jump to
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the corresponding label. */
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struct return_statements_t
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{
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tree label;
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gimple stmt;
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};
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typedef struct return_statements_t return_statements_t;
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DEF_VEC_O(return_statements_t);
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DEF_VEC_ALLOC_O(return_statements_t,heap);
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struct lower_data
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{
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/* Block the current statement belongs to. */
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tree block;
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/* A vector of label and return statements to be moved to the end
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of the function. */
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VEC(return_statements_t,heap) *return_statements;
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/* True if the current statement cannot fall through. */
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bool cannot_fallthru;
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/* True if the function calls __builtin_setjmp. */
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bool calls_builtin_setjmp;
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};
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static void lower_stmt (gimple_stmt_iterator *, struct lower_data *);
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static void lower_gimple_bind (gimple_stmt_iterator *, struct lower_data *);
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static void lower_gimple_return (gimple_stmt_iterator *, struct lower_data *);
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static void lower_builtin_setjmp (gimple_stmt_iterator *);
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/* Lower the body of current_function_decl from High GIMPLE into Low
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GIMPLE. */
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static unsigned int
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lower_function_body (void)
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{
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struct lower_data data;
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gimple_seq body = gimple_body (current_function_decl);
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gimple_seq lowered_body;
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gimple_stmt_iterator i;
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gimple bind;
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tree t;
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gimple x;
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/* The gimplifier should've left a body of exactly one statement,
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namely a GIMPLE_BIND. */
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gcc_assert (gimple_seq_first (body) == gimple_seq_last (body)
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&& gimple_code (gimple_seq_first_stmt (body)) == GIMPLE_BIND);
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memset (&data, 0, sizeof (data));
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data.block = DECL_INITIAL (current_function_decl);
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BLOCK_SUBBLOCKS (data.block) = NULL_TREE;
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BLOCK_CHAIN (data.block) = NULL_TREE;
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TREE_ASM_WRITTEN (data.block) = 1;
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data.return_statements = VEC_alloc (return_statements_t, heap, 8);
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bind = gimple_seq_first_stmt (body);
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lowered_body = NULL;
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gimple_seq_add_stmt (&lowered_body, bind);
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i = gsi_start (lowered_body);
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lower_gimple_bind (&i, &data);
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/* Once the old body has been lowered, replace it with the new
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lowered sequence. */
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gimple_set_body (current_function_decl, lowered_body);
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i = gsi_last (lowered_body);
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/* If the function falls off the end, we need a null return statement.
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If we've already got one in the return_statements vector, we don't
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need to do anything special. Otherwise build one by hand. */
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if (gimple_seq_may_fallthru (lowered_body)
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&& (VEC_empty (return_statements_t, data.return_statements)
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|| gimple_return_retval (VEC_last (return_statements_t,
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data.return_statements)->stmt) != NULL))
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{
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x = gimple_build_return (NULL);
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gimple_set_location (x, cfun->function_end_locus);
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gimple_set_block (x, DECL_INITIAL (current_function_decl));
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gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
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}
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/* If we lowered any return statements, emit the representative
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at the end of the function. */
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while (!VEC_empty (return_statements_t, data.return_statements))
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{
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return_statements_t t;
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/* Unfortunately, we can't use VEC_pop because it returns void for
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objects. */
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t = *VEC_last (return_statements_t, data.return_statements);
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VEC_truncate (return_statements_t,
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data.return_statements,
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VEC_length (return_statements_t,
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data.return_statements) - 1);
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x = gimple_build_label (t.label);
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gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
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gsi_insert_after (&i, t.stmt, GSI_CONTINUE_LINKING);
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}
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/* If the function calls __builtin_setjmp, we need to emit the computed
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goto that will serve as the unique dispatcher for all the receivers. */
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if (data.calls_builtin_setjmp)
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{
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tree disp_label, disp_var, arg;
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/* Build 'DISP_LABEL:' and insert. */
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disp_label = create_artificial_label (cfun->function_end_locus);
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/* This mark will create forward edges from every call site. */
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DECL_NONLOCAL (disp_label) = 1;
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cfun->has_nonlocal_label = 1;
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x = gimple_build_label (disp_label);
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gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
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/* Build 'DISP_VAR = __builtin_setjmp_dispatcher (DISP_LABEL);'
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and insert. */
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disp_var = create_tmp_var (ptr_type_node, "setjmpvar");
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arg = build_addr (disp_label, current_function_decl);
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t = implicit_built_in_decls[BUILT_IN_SETJMP_DISPATCHER];
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x = gimple_build_call (t, 1, arg);
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gimple_call_set_lhs (x, disp_var);
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/* Build 'goto DISP_VAR;' and insert. */
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gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
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x = gimple_build_goto (disp_var);
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gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
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}
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gcc_assert (data.block == DECL_INITIAL (current_function_decl));
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BLOCK_SUBBLOCKS (data.block)
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= blocks_nreverse (BLOCK_SUBBLOCKS (data.block));
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clear_block_marks (data.block);
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VEC_free(return_statements_t, heap, data.return_statements);
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return 0;
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}
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struct gimple_opt_pass pass_lower_cf =
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{
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{
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GIMPLE_PASS,
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"lower", /* name */
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NULL, /* gate */
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lower_function_body, /* execute */
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NULL, /* sub */
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NULL, /* next */
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0, /* static_pass_number */
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TV_NONE, /* tv_id */
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PROP_gimple_any, /* properties_required */
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PROP_gimple_lcf, /* properties_provided */
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0, /* properties_destroyed */
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0, /* todo_flags_start */
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0 /* todo_flags_finish */
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}
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};
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/* Verify if the type of the argument matches that of the function
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declaration. If we cannot verify this or there is a mismatch,
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return false. */
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static bool
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gimple_check_call_args (gimple stmt, tree fndecl)
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{
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tree parms, p;
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unsigned int i, nargs;
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/* Calls to internal functions always match their signature. */
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if (gimple_call_internal_p (stmt))
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return true;
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nargs = gimple_call_num_args (stmt);
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/* Get argument types for verification. */
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if (fndecl)
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parms = TYPE_ARG_TYPES (TREE_TYPE (fndecl));
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else
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parms = TYPE_ARG_TYPES (gimple_call_fntype (stmt));
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/* Verify if the type of the argument matches that of the function
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declaration. If we cannot verify this or there is a mismatch,
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return false. */
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if (fndecl && DECL_ARGUMENTS (fndecl))
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{
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for (i = 0, p = DECL_ARGUMENTS (fndecl);
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i < nargs;
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i++, p = DECL_CHAIN (p))
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{
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/* We cannot distinguish a varargs function from the case
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of excess parameters, still deferring the inlining decision
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to the callee is possible. */
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if (!p)
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break;
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if (p == error_mark_node
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|| gimple_call_arg (stmt, i) == error_mark_node
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|| !fold_convertible_p (DECL_ARG_TYPE (p),
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gimple_call_arg (stmt, i)))
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return false;
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}
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}
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else if (parms)
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{
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for (i = 0, p = parms; i < nargs; i++, p = TREE_CHAIN (p))
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{
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/* If this is a varargs function defer inlining decision
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to callee. */
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if (!p)
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break;
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if (TREE_VALUE (p) == error_mark_node
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|| gimple_call_arg (stmt, i) == error_mark_node
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|| TREE_CODE (TREE_VALUE (p)) == VOID_TYPE
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|| !fold_convertible_p (TREE_VALUE (p),
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gimple_call_arg (stmt, i)))
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return false;
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}
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}
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else
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{
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if (nargs != 0)
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return false;
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}
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return true;
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}
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/* Verify if the type of the argument and lhs of CALL_STMT matches
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that of the function declaration CALLEE.
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If we cannot verify this or there is a mismatch, return false. */
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bool
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gimple_check_call_matching_types (gimple call_stmt, tree callee)
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{
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tree lhs;
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if ((DECL_RESULT (callee)
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&& !DECL_BY_REFERENCE (DECL_RESULT (callee))
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&& (lhs = gimple_call_lhs (call_stmt)) != NULL_TREE
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&& !useless_type_conversion_p (TREE_TYPE (DECL_RESULT (callee)),
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TREE_TYPE (lhs))
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&& !fold_convertible_p (TREE_TYPE (DECL_RESULT (callee)), lhs))
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|| !gimple_check_call_args (call_stmt, callee))
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return false;
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return true;
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}
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/* Lower sequence SEQ. Unlike gimplification the statements are not relowered
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when they are changed -- if this has to be done, the lowering routine must
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do it explicitly. DATA is passed through the recursion. */
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static void
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lower_sequence (gimple_seq seq, struct lower_data *data)
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{
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gimple_stmt_iterator gsi;
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for (gsi = gsi_start (seq); !gsi_end_p (gsi); )
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lower_stmt (&gsi, data);
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}
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/* Lower the OpenMP directive statement pointed by GSI. DATA is
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passed through the recursion. */
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static void
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lower_omp_directive (gimple_stmt_iterator *gsi, struct lower_data *data)
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{
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gimple stmt;
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stmt = gsi_stmt (*gsi);
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lower_sequence (gimple_omp_body (stmt), data);
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gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
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gsi_insert_seq_before (gsi, gimple_omp_body (stmt), GSI_SAME_STMT);
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gimple_omp_set_body (stmt, NULL);
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gsi_remove (gsi, false);
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}
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/* Lower statement GSI. DATA is passed through the recursion. We try to
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track the fallthruness of statements and get rid of unreachable return
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statements in order to prevent the EH lowering pass from adding useless
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edges that can cause bogus warnings to be issued later; this guess need
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not be 100% accurate, simply be conservative and reset cannot_fallthru
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to false if we don't know. */
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static void
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lower_stmt (gimple_stmt_iterator *gsi, struct lower_data *data)
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{
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gimple stmt = gsi_stmt (*gsi);
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gimple_set_block (stmt, data->block);
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switch (gimple_code (stmt))
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{
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case GIMPLE_BIND:
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lower_gimple_bind (gsi, data);
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/* Propagate fallthruness. */
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return;
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case GIMPLE_COND:
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case GIMPLE_GOTO:
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case GIMPLE_SWITCH:
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data->cannot_fallthru = true;
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gsi_next (gsi);
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return;
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case GIMPLE_RETURN:
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if (data->cannot_fallthru)
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{
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gsi_remove (gsi, false);
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/* Propagate fallthruness. */
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}
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else
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{
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lower_gimple_return (gsi, data);
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data->cannot_fallthru = true;
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}
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return;
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case GIMPLE_TRY:
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{
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bool try_cannot_fallthru;
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lower_sequence (gimple_try_eval (stmt), data);
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try_cannot_fallthru = data->cannot_fallthru;
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data->cannot_fallthru = false;
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lower_sequence (gimple_try_cleanup (stmt), data);
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/* See gimple_stmt_may_fallthru for the rationale. */
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if (gimple_try_kind (stmt) == GIMPLE_TRY_FINALLY)
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{
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data->cannot_fallthru |= try_cannot_fallthru;
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gsi_next (gsi);
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return;
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}
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}
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break;
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case GIMPLE_CATCH:
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data->cannot_fallthru = false;
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lower_sequence (gimple_catch_handler (stmt), data);
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break;
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case GIMPLE_EH_FILTER:
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data->cannot_fallthru = false;
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lower_sequence (gimple_eh_filter_failure (stmt), data);
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break;
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case GIMPLE_NOP:
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case GIMPLE_ASM:
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case GIMPLE_ASSIGN:
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case GIMPLE_PREDICT:
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case GIMPLE_LABEL:
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case GIMPLE_EH_MUST_NOT_THROW:
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case GIMPLE_OMP_FOR:
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case GIMPLE_OMP_SECTIONS:
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case GIMPLE_OMP_SECTIONS_SWITCH:
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case GIMPLE_OMP_SECTION:
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case GIMPLE_OMP_SINGLE:
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case GIMPLE_OMP_MASTER:
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case GIMPLE_OMP_ORDERED:
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case GIMPLE_OMP_CRITICAL:
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case GIMPLE_OMP_RETURN:
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case GIMPLE_OMP_ATOMIC_LOAD:
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case GIMPLE_OMP_ATOMIC_STORE:
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case GIMPLE_OMP_CONTINUE:
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break;
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case GIMPLE_CALL:
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{
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tree decl = gimple_call_fndecl (stmt);
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if (decl
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&& DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL
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&& DECL_FUNCTION_CODE (decl) == BUILT_IN_SETJMP)
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{
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lower_builtin_setjmp (gsi);
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data->cannot_fallthru = false;
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data->calls_builtin_setjmp = true;
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return;
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}
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if (decl && (flags_from_decl_or_type (decl) & ECF_NORETURN))
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{
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data->cannot_fallthru = true;
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gsi_next (gsi);
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return;
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}
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}
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break;
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case GIMPLE_OMP_PARALLEL:
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case GIMPLE_OMP_TASK:
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data->cannot_fallthru = false;
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lower_omp_directive (gsi, data);
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data->cannot_fallthru = false;
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return;
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default:
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gcc_unreachable ();
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}
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data->cannot_fallthru = false;
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gsi_next (gsi);
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}
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/* Lower a bind_expr TSI. DATA is passed through the recursion. */
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static void
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lower_gimple_bind (gimple_stmt_iterator *gsi, struct lower_data *data)
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{
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tree old_block = data->block;
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gimple stmt = gsi_stmt (*gsi);
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tree new_block = gimple_bind_block (stmt);
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if (new_block)
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{
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if (new_block == old_block)
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{
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/* The outermost block of the original function may not be the
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outermost statement chain of the gimplified function. So we
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may see the outermost block just inside the function. */
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gcc_assert (new_block == DECL_INITIAL (current_function_decl));
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new_block = NULL;
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}
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else
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{
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/* We do not expect to handle duplicate blocks. */
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gcc_assert (!TREE_ASM_WRITTEN (new_block));
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TREE_ASM_WRITTEN (new_block) = 1;
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/* Block tree may get clobbered by inlining. Normally this would
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be fixed in rest_of_decl_compilation using block notes, but
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since we are not going to emit them, it is up to us. */
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BLOCK_CHAIN (new_block) = BLOCK_SUBBLOCKS (old_block);
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BLOCK_SUBBLOCKS (old_block) = new_block;
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BLOCK_SUBBLOCKS (new_block) = NULL_TREE;
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BLOCK_SUPERCONTEXT (new_block) = old_block;
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data->block = new_block;
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}
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}
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record_vars (gimple_bind_vars (stmt));
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lower_sequence (gimple_bind_body (stmt), data);
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if (new_block)
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{
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gcc_assert (data->block == new_block);
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BLOCK_SUBBLOCKS (new_block)
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= blocks_nreverse (BLOCK_SUBBLOCKS (new_block));
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data->block = old_block;
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}
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/* The GIMPLE_BIND no longer carries any useful information -- kill it. */
|
||
gsi_insert_seq_before (gsi, gimple_bind_body (stmt), GSI_SAME_STMT);
|
||
gsi_remove (gsi, false);
|
||
}
|
||
|
||
/* Try to determine whether a TRY_CATCH expression can fall through.
|
||
This is a subroutine of block_may_fallthru. */
|
||
|
||
static bool
|
||
try_catch_may_fallthru (const_tree stmt)
|
||
{
|
||
tree_stmt_iterator i;
|
||
|
||
/* If the TRY block can fall through, the whole TRY_CATCH can
|
||
fall through. */
|
||
if (block_may_fallthru (TREE_OPERAND (stmt, 0)))
|
||
return true;
|
||
|
||
i = tsi_start (TREE_OPERAND (stmt, 1));
|
||
switch (TREE_CODE (tsi_stmt (i)))
|
||
{
|
||
case CATCH_EXPR:
|
||
/* We expect to see a sequence of CATCH_EXPR trees, each with a
|
||
catch expression and a body. The whole TRY_CATCH may fall
|
||
through iff any of the catch bodies falls through. */
|
||
for (; !tsi_end_p (i); tsi_next (&i))
|
||
{
|
||
if (block_may_fallthru (CATCH_BODY (tsi_stmt (i))))
|
||
return true;
|
||
}
|
||
return false;
|
||
|
||
case EH_FILTER_EXPR:
|
||
/* The exception filter expression only matters if there is an
|
||
exception. If the exception does not match EH_FILTER_TYPES,
|
||
we will execute EH_FILTER_FAILURE, and we will fall through
|
||
if that falls through. If the exception does match
|
||
EH_FILTER_TYPES, the stack unwinder will continue up the
|
||
stack, so we will not fall through. We don't know whether we
|
||
will throw an exception which matches EH_FILTER_TYPES or not,
|
||
so we just ignore EH_FILTER_TYPES and assume that we might
|
||
throw an exception which doesn't match. */
|
||
return block_may_fallthru (EH_FILTER_FAILURE (tsi_stmt (i)));
|
||
|
||
default:
|
||
/* This case represents statements to be executed when an
|
||
exception occurs. Those statements are implicitly followed
|
||
by a RESX statement to resume execution after the exception.
|
||
So in this case the TRY_CATCH never falls through. */
|
||
return false;
|
||
}
|
||
}
|
||
|
||
|
||
/* Same as above, but for a GIMPLE_TRY_CATCH. */
|
||
|
||
static bool
|
||
gimple_try_catch_may_fallthru (gimple stmt)
|
||
{
|
||
gimple_stmt_iterator i;
|
||
|
||
/* We don't handle GIMPLE_TRY_FINALLY. */
|
||
gcc_assert (gimple_try_kind (stmt) == GIMPLE_TRY_CATCH);
|
||
|
||
/* If the TRY block can fall through, the whole TRY_CATCH can
|
||
fall through. */
|
||
if (gimple_seq_may_fallthru (gimple_try_eval (stmt)))
|
||
return true;
|
||
|
||
i = gsi_start (gimple_try_cleanup (stmt));
|
||
switch (gimple_code (gsi_stmt (i)))
|
||
{
|
||
case GIMPLE_CATCH:
|
||
/* We expect to see a sequence of GIMPLE_CATCH stmts, each with a
|
||
catch expression and a body. The whole try/catch may fall
|
||
through iff any of the catch bodies falls through. */
|
||
for (; !gsi_end_p (i); gsi_next (&i))
|
||
{
|
||
if (gimple_seq_may_fallthru (gimple_catch_handler (gsi_stmt (i))))
|
||
return true;
|
||
}
|
||
return false;
|
||
|
||
case GIMPLE_EH_FILTER:
|
||
/* The exception filter expression only matters if there is an
|
||
exception. If the exception does not match EH_FILTER_TYPES,
|
||
we will execute EH_FILTER_FAILURE, and we will fall through
|
||
if that falls through. If the exception does match
|
||
EH_FILTER_TYPES, the stack unwinder will continue up the
|
||
stack, so we will not fall through. We don't know whether we
|
||
will throw an exception which matches EH_FILTER_TYPES or not,
|
||
so we just ignore EH_FILTER_TYPES and assume that we might
|
||
throw an exception which doesn't match. */
|
||
return gimple_seq_may_fallthru (gimple_eh_filter_failure (gsi_stmt (i)));
|
||
|
||
default:
|
||
/* This case represents statements to be executed when an
|
||
exception occurs. Those statements are implicitly followed
|
||
by a GIMPLE_RESX to resume execution after the exception. So
|
||
in this case the try/catch never falls through. */
|
||
return false;
|
||
}
|
||
}
|
||
|
||
|
||
/* Try to determine if we can fall out of the bottom of BLOCK. This guess
|
||
need not be 100% accurate; simply be conservative and return true if we
|
||
don't know. This is used only to avoid stupidly generating extra code.
|
||
If we're wrong, we'll just delete the extra code later. */
|
||
|
||
bool
|
||
block_may_fallthru (const_tree block)
|
||
{
|
||
/* This CONST_CAST is okay because expr_last returns its argument
|
||
unmodified and we assign it to a const_tree. */
|
||
const_tree stmt = expr_last (CONST_CAST_TREE(block));
|
||
|
||
switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
|
||
{
|
||
case GOTO_EXPR:
|
||
case RETURN_EXPR:
|
||
/* Easy cases. If the last statement of the block implies
|
||
control transfer, then we can't fall through. */
|
||
return false;
|
||
|
||
case SWITCH_EXPR:
|
||
/* If SWITCH_LABELS is set, this is lowered, and represents a
|
||
branch to a selected label and hence can not fall through.
|
||
Otherwise SWITCH_BODY is set, and the switch can fall
|
||
through. */
|
||
return SWITCH_LABELS (stmt) == NULL_TREE;
|
||
|
||
case COND_EXPR:
|
||
if (block_may_fallthru (COND_EXPR_THEN (stmt)))
|
||
return true;
|
||
return block_may_fallthru (COND_EXPR_ELSE (stmt));
|
||
|
||
case BIND_EXPR:
|
||
return block_may_fallthru (BIND_EXPR_BODY (stmt));
|
||
|
||
case TRY_CATCH_EXPR:
|
||
return try_catch_may_fallthru (stmt);
|
||
|
||
case TRY_FINALLY_EXPR:
|
||
/* The finally clause is always executed after the try clause,
|
||
so if it does not fall through, then the try-finally will not
|
||
fall through. Otherwise, if the try clause does not fall
|
||
through, then when the finally clause falls through it will
|
||
resume execution wherever the try clause was going. So the
|
||
whole try-finally will only fall through if both the try
|
||
clause and the finally clause fall through. */
|
||
return (block_may_fallthru (TREE_OPERAND (stmt, 0))
|
||
&& block_may_fallthru (TREE_OPERAND (stmt, 1)));
|
||
|
||
case MODIFY_EXPR:
|
||
if (TREE_CODE (TREE_OPERAND (stmt, 1)) == CALL_EXPR)
|
||
stmt = TREE_OPERAND (stmt, 1);
|
||
else
|
||
return true;
|
||
/* FALLTHRU */
|
||
|
||
case CALL_EXPR:
|
||
/* Functions that do not return do not fall through. */
|
||
return (call_expr_flags (stmt) & ECF_NORETURN) == 0;
|
||
|
||
case CLEANUP_POINT_EXPR:
|
||
return block_may_fallthru (TREE_OPERAND (stmt, 0));
|
||
|
||
default:
|
||
return true;
|
||
}
|
||
}
|
||
|
||
|
||
/* Try to determine if we can continue executing the statement
|
||
immediately following STMT. This guess need not be 100% accurate;
|
||
simply be conservative and return true if we don't know. This is
|
||
used only to avoid stupidly generating extra code. If we're wrong,
|
||
we'll just delete the extra code later. */
|
||
|
||
bool
|
||
gimple_stmt_may_fallthru (gimple stmt)
|
||
{
|
||
if (!stmt)
|
||
return true;
|
||
|
||
switch (gimple_code (stmt))
|
||
{
|
||
case GIMPLE_GOTO:
|
||
case GIMPLE_RETURN:
|
||
case GIMPLE_RESX:
|
||
/* Easy cases. If the last statement of the seq implies
|
||
control transfer, then we can't fall through. */
|
||
return false;
|
||
|
||
case GIMPLE_SWITCH:
|
||
/* Switch has already been lowered and represents a branch
|
||
to a selected label and hence can't fall through. */
|
||
return false;
|
||
|
||
case GIMPLE_COND:
|
||
/* GIMPLE_COND's are already lowered into a two-way branch. They
|
||
can't fall through. */
|
||
return false;
|
||
|
||
case GIMPLE_BIND:
|
||
return gimple_seq_may_fallthru (gimple_bind_body (stmt));
|
||
|
||
case GIMPLE_TRY:
|
||
if (gimple_try_kind (stmt) == GIMPLE_TRY_CATCH)
|
||
return gimple_try_catch_may_fallthru (stmt);
|
||
|
||
/* It must be a GIMPLE_TRY_FINALLY. */
|
||
|
||
/* The finally clause is always executed after the try clause,
|
||
so if it does not fall through, then the try-finally will not
|
||
fall through. Otherwise, if the try clause does not fall
|
||
through, then when the finally clause falls through it will
|
||
resume execution wherever the try clause was going. So the
|
||
whole try-finally will only fall through if both the try
|
||
clause and the finally clause fall through. */
|
||
return (gimple_seq_may_fallthru (gimple_try_eval (stmt))
|
||
&& gimple_seq_may_fallthru (gimple_try_cleanup (stmt)));
|
||
|
||
case GIMPLE_CALL:
|
||
/* Functions that do not return do not fall through. */
|
||
return (gimple_call_flags (stmt) & ECF_NORETURN) == 0;
|
||
|
||
default:
|
||
return true;
|
||
}
|
||
}
|
||
|
||
|
||
/* Same as gimple_stmt_may_fallthru, but for the gimple sequence SEQ. */
|
||
|
||
bool
|
||
gimple_seq_may_fallthru (gimple_seq seq)
|
||
{
|
||
return gimple_stmt_may_fallthru (gimple_seq_last_stmt (seq));
|
||
}
|
||
|
||
|
||
/* Lower a GIMPLE_RETURN GSI. DATA is passed through the recursion. */
|
||
|
||
static void
|
||
lower_gimple_return (gimple_stmt_iterator *gsi, struct lower_data *data)
|
||
{
|
||
gimple stmt = gsi_stmt (*gsi);
|
||
gimple t;
|
||
int i;
|
||
return_statements_t tmp_rs;
|
||
|
||
/* Match this up with an existing return statement that's been created. */
|
||
for (i = VEC_length (return_statements_t, data->return_statements) - 1;
|
||
i >= 0; i--)
|
||
{
|
||
tmp_rs = *VEC_index (return_statements_t, data->return_statements, i);
|
||
|
||
if (gimple_return_retval (stmt) == gimple_return_retval (tmp_rs.stmt))
|
||
{
|
||
/* Remove the line number from the representative return statement.
|
||
It now fills in for many such returns. Failure to remove this
|
||
will result in incorrect results for coverage analysis. */
|
||
gimple_set_location (tmp_rs.stmt, UNKNOWN_LOCATION);
|
||
|
||
goto found;
|
||
}
|
||
}
|
||
|
||
/* Not found. Create a new label and record the return statement. */
|
||
tmp_rs.label = create_artificial_label (cfun->function_end_locus);
|
||
tmp_rs.stmt = stmt;
|
||
VEC_safe_push (return_statements_t, heap, data->return_statements, &tmp_rs);
|
||
|
||
/* Generate a goto statement and remove the return statement. */
|
||
found:
|
||
/* When not optimizing, make sure user returns are preserved. */
|
||
if (!optimize && gimple_has_location (stmt))
|
||
DECL_ARTIFICIAL (tmp_rs.label) = 0;
|
||
t = gimple_build_goto (tmp_rs.label);
|
||
gimple_set_location (t, gimple_location (stmt));
|
||
gimple_set_block (t, gimple_block (stmt));
|
||
gsi_insert_before (gsi, t, GSI_SAME_STMT);
|
||
gsi_remove (gsi, false);
|
||
}
|
||
|
||
/* Lower a __builtin_setjmp GSI.
|
||
|
||
__builtin_setjmp is passed a pointer to an array of five words (not
|
||
all will be used on all machines). It operates similarly to the C
|
||
library function of the same name, but is more efficient.
|
||
|
||
It is lowered into 3 other builtins, namely __builtin_setjmp_setup,
|
||
__builtin_setjmp_dispatcher and __builtin_setjmp_receiver, but with
|
||
__builtin_setjmp_dispatcher shared among all the instances; that's
|
||
why it is only emitted at the end by lower_function_body.
|
||
|
||
After full lowering, the body of the function should look like:
|
||
|
||
{
|
||
void * setjmpvar.0;
|
||
int D.1844;
|
||
int D.2844;
|
||
|
||
[...]
|
||
|
||
__builtin_setjmp_setup (&buf, &<D1847>);
|
||
D.1844 = 0;
|
||
goto <D1846>;
|
||
<D1847>:;
|
||
__builtin_setjmp_receiver (&<D1847>);
|
||
D.1844 = 1;
|
||
<D1846>:;
|
||
if (D.1844 == 0) goto <D1848>; else goto <D1849>;
|
||
|
||
[...]
|
||
|
||
__builtin_setjmp_setup (&buf, &<D2847>);
|
||
D.2844 = 0;
|
||
goto <D2846>;
|
||
<D2847>:;
|
||
__builtin_setjmp_receiver (&<D2847>);
|
||
D.2844 = 1;
|
||
<D2846>:;
|
||
if (D.2844 == 0) goto <D2848>; else goto <D2849>;
|
||
|
||
[...]
|
||
|
||
<D3850>:;
|
||
return;
|
||
<D3853>: [non-local];
|
||
setjmpvar.0 = __builtin_setjmp_dispatcher (&<D3853>);
|
||
goto setjmpvar.0;
|
||
}
|
||
|
||
The dispatcher block will be both the unique destination of all the
|
||
abnormal call edges and the unique source of all the abnormal edges
|
||
to the receivers, thus keeping the complexity explosion localized. */
|
||
|
||
static void
|
||
lower_builtin_setjmp (gimple_stmt_iterator *gsi)
|
||
{
|
||
gimple stmt = gsi_stmt (*gsi);
|
||
location_t loc = gimple_location (stmt);
|
||
tree cont_label = create_artificial_label (loc);
|
||
tree next_label = create_artificial_label (loc);
|
||
tree dest, t, arg;
|
||
gimple g;
|
||
|
||
/* NEXT_LABEL is the label __builtin_longjmp will jump to. Its address is
|
||
passed to both __builtin_setjmp_setup and __builtin_setjmp_receiver. */
|
||
FORCED_LABEL (next_label) = 1;
|
||
|
||
dest = gimple_call_lhs (stmt);
|
||
|
||
/* Build '__builtin_setjmp_setup (BUF, NEXT_LABEL)' and insert. */
|
||
arg = build_addr (next_label, current_function_decl);
|
||
t = implicit_built_in_decls[BUILT_IN_SETJMP_SETUP];
|
||
g = gimple_build_call (t, 2, gimple_call_arg (stmt, 0), arg);
|
||
gimple_set_location (g, loc);
|
||
gimple_set_block (g, gimple_block (stmt));
|
||
gsi_insert_before (gsi, g, GSI_SAME_STMT);
|
||
|
||
/* Build 'DEST = 0' and insert. */
|
||
if (dest)
|
||
{
|
||
g = gimple_build_assign (dest, build_zero_cst (TREE_TYPE (dest)));
|
||
gimple_set_location (g, loc);
|
||
gimple_set_block (g, gimple_block (stmt));
|
||
gsi_insert_before (gsi, g, GSI_SAME_STMT);
|
||
}
|
||
|
||
/* Build 'goto CONT_LABEL' and insert. */
|
||
g = gimple_build_goto (cont_label);
|
||
gsi_insert_before (gsi, g, GSI_SAME_STMT);
|
||
|
||
/* Build 'NEXT_LABEL:' and insert. */
|
||
g = gimple_build_label (next_label);
|
||
gsi_insert_before (gsi, g, GSI_SAME_STMT);
|
||
|
||
/* Build '__builtin_setjmp_receiver (NEXT_LABEL)' and insert. */
|
||
arg = build_addr (next_label, current_function_decl);
|
||
t = implicit_built_in_decls[BUILT_IN_SETJMP_RECEIVER];
|
||
g = gimple_build_call (t, 1, arg);
|
||
gimple_set_location (g, loc);
|
||
gimple_set_block (g, gimple_block (stmt));
|
||
gsi_insert_before (gsi, g, GSI_SAME_STMT);
|
||
|
||
/* Build 'DEST = 1' and insert. */
|
||
if (dest)
|
||
{
|
||
g = gimple_build_assign (dest, fold_convert_loc (loc, TREE_TYPE (dest),
|
||
integer_one_node));
|
||
gimple_set_location (g, loc);
|
||
gimple_set_block (g, gimple_block (stmt));
|
||
gsi_insert_before (gsi, g, GSI_SAME_STMT);
|
||
}
|
||
|
||
/* Build 'CONT_LABEL:' and insert. */
|
||
g = gimple_build_label (cont_label);
|
||
gsi_insert_before (gsi, g, GSI_SAME_STMT);
|
||
|
||
/* Remove the call to __builtin_setjmp. */
|
||
gsi_remove (gsi, false);
|
||
}
|
||
|
||
|
||
/* Record the variables in VARS into function FN. */
|
||
|
||
void
|
||
record_vars_into (tree vars, tree fn)
|
||
{
|
||
if (fn != current_function_decl)
|
||
push_cfun (DECL_STRUCT_FUNCTION (fn));
|
||
|
||
for (; vars; vars = DECL_CHAIN (vars))
|
||
{
|
||
tree var = vars;
|
||
|
||
/* BIND_EXPRs contains also function/type/constant declarations
|
||
we don't need to care about. */
|
||
if (TREE_CODE (var) != VAR_DECL)
|
||
continue;
|
||
|
||
/* Nothing to do in this case. */
|
||
if (DECL_EXTERNAL (var))
|
||
continue;
|
||
|
||
/* Record the variable. */
|
||
add_local_decl (cfun, var);
|
||
if (gimple_referenced_vars (cfun))
|
||
add_referenced_var (var);
|
||
}
|
||
|
||
if (fn != current_function_decl)
|
||
pop_cfun ();
|
||
}
|
||
|
||
|
||
/* Record the variables in VARS into current_function_decl. */
|
||
|
||
void
|
||
record_vars (tree vars)
|
||
{
|
||
record_vars_into (vars, current_function_decl);
|
||
}
|