-/* Tree lowering pass. Lowers GIMPLE into unstructured form.
+/* GIMPLE lowering pass. Converts High GIMPLE into Low GIMPLE.
- Copyright (C) 2003, 2005 Free Software Foundation, Inc.
+ Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
+ 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 2, or (at your option) any later
+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
for more details.
You should have received a copy of the GNU General Public License
-along with GCC; see the file COPYING. If not, write to the Free
-Software Foundation, 59 Temple Place - Suite 330, Boston, MA
-02111-1307, USA. */
+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 "tm.h"
#include "tree.h"
-#include "rtl.h"
-#include "errors.h"
-#include "varray.h"
-#include "tree-gimple.h"
+#include "gimple.h"
+#include "tree-iterator.h"
#include "tree-inline.h"
-#include "diagnostic.h"
-#include "langhooks.h"
-#include "langhooks-def.h"
#include "tree-flow.h"
-#include "timevar.h"
-#include "except.h"
-#include "hashtab.h"
#include "flags.h"
#include "function.h"
-#include "expr.h"
-#include "toplev.h"
+#include "diagnostic-core.h"
#include "tree-pass.h"
+/* The differences between High GIMPLE and Low GIMPLE are the
+ following:
+
+ 1- Lexical scopes are removed (i.e., GIMPLE_BIND disappears).
+
+ 2- GIMPLE_TRY and GIMPLE_CATCH are converted to abnormal control
+ flow and exception regions are built as an on-the-side region
+ hierarchy (See tree-eh.c:lower_eh_constructs).
+
+ 3- Multiple identical return statements are grouped into a single
+ return and gotos to the unique return site. */
+
+/* Match a return statement with a label. During lowering, we identify
+ identical return statements and replace duplicates with a jump to
+ the corresponding label. */
+struct return_statements_t
+{
+ tree label;
+ gimple stmt;
+};
+typedef struct return_statements_t return_statements_t;
+
+DEF_VEC_O(return_statements_t);
+DEF_VEC_ALLOC_O(return_statements_t,heap);
+
struct lower_data
{
/* Block the current statement belongs to. */
tree block;
- /* A TREE_LIST of label and return statements to be moved to the end
+ /* A vector of label and return statements to be moved to the end
of the function. */
- tree return_statements;
+ VEC(return_statements_t,heap) *return_statements;
+
+ /* True if the current statement cannot fall through. */
+ bool cannot_fallthru;
+
+ /* True if the function calls __builtin_setjmp. */
+ bool calls_builtin_setjmp;
};
-static void lower_stmt (tree_stmt_iterator *, struct lower_data *);
-static void lower_bind_expr (tree_stmt_iterator *, struct lower_data *);
-static void lower_cond_expr (tree_stmt_iterator *, struct lower_data *);
-static void lower_return_expr (tree_stmt_iterator *, struct lower_data *);
-static bool expand_var_p (tree);
+static void lower_stmt (gimple_stmt_iterator *, struct lower_data *);
+static void lower_gimple_bind (gimple_stmt_iterator *, struct lower_data *);
+static void lower_gimple_return (gimple_stmt_iterator *, struct lower_data *);
+static void lower_builtin_setjmp (gimple_stmt_iterator *);
-/* Lowers the body of current_function_decl. */
-static void
+/* Lower the body of current_function_decl from High GIMPLE into Low
+ GIMPLE. */
+
+static unsigned int
lower_function_body (void)
{
struct lower_data data;
- tree *body_p = &DECL_SAVED_TREE (current_function_decl);
- tree bind = *body_p;
- tree_stmt_iterator i;
- tree t, x;
-
- gcc_assert (TREE_CODE (bind) == BIND_EXPR);
-
+ gimple_seq body = gimple_body (current_function_decl);
+ gimple_seq lowered_body;
+ gimple_stmt_iterator i;
+ gimple bind;
+ tree t;
+ gimple x;
+
+ /* The gimplifier should've left a body of exactly one statement,
+ namely a GIMPLE_BIND. */
+ gcc_assert (gimple_seq_first (body) == gimple_seq_last (body)
+ && gimple_code (gimple_seq_first_stmt (body)) == GIMPLE_BIND);
+
+ memset (&data, 0, sizeof (data));
data.block = DECL_INITIAL (current_function_decl);
BLOCK_SUBBLOCKS (data.block) = NULL_TREE;
BLOCK_CHAIN (data.block) = NULL_TREE;
TREE_ASM_WRITTEN (data.block) = 1;
+ data.return_statements = VEC_alloc (return_statements_t, heap, 8);
- data.return_statements = NULL_TREE;
+ bind = gimple_seq_first_stmt (body);
+ lowered_body = NULL;
+ gimple_seq_add_stmt (&lowered_body, bind);
+ i = gsi_start (lowered_body);
+ lower_gimple_bind (&i, &data);
- *body_p = alloc_stmt_list ();
- i = tsi_start (*body_p);
- tsi_link_after (&i, bind, TSI_NEW_STMT);
- lower_bind_expr (&i, &data);
+ /* Once the old body has been lowered, replace it with the new
+ lowered sequence. */
+ gimple_set_body (current_function_decl, lowered_body);
- i = tsi_last (*body_p);
+ i = gsi_last (lowered_body);
/* If the function falls off the end, we need a null return statement.
- If we've already got one in the return_statements list, we don't
+ If we've already got one in the return_statements vector, we don't
need to do anything special. Otherwise build one by hand. */
- if (block_may_fallthru (*body_p)
- && (data.return_statements == NULL
- || TREE_OPERAND (TREE_VALUE (data.return_statements), 0) != NULL))
+ if (gimple_seq_may_fallthru (lowered_body)
+ && (VEC_empty (return_statements_t, data.return_statements)
+ || gimple_return_retval (VEC_last (return_statements_t,
+ data.return_statements)->stmt) != NULL))
{
- x = build (RETURN_EXPR, void_type_node, NULL);
- SET_EXPR_LOCATION (x, cfun->function_end_locus);
- tsi_link_after (&i, x, TSI_CONTINUE_LINKING);
+ x = gimple_build_return (NULL);
+ gimple_set_location (x, cfun->function_end_locus);
+ gimple_set_block (x, DECL_INITIAL (current_function_decl));
+ gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
}
/* If we lowered any return statements, emit the representative
at the end of the function. */
- for (t = data.return_statements ; t ; t = TREE_CHAIN (t))
+ while (!VEC_empty (return_statements_t, data.return_statements))
{
- x = build (LABEL_EXPR, void_type_node, TREE_PURPOSE (t));
- tsi_link_after (&i, x, TSI_CONTINUE_LINKING);
-
- /* 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. */
- x = TREE_VALUE (t);
-#ifdef USE_MAPPED_LOCATION
- SET_EXPR_LOCATION (x, UNKNOWN_LOCATION);
-#else
- SET_EXPR_LOCUS (x, NULL);
-#endif
- tsi_link_after (&i, x, TSI_CONTINUE_LINKING);
+ return_statements_t t;
+
+ /* Unfortunately, we can't use VEC_pop because it returns void for
+ objects. */
+ t = *VEC_last (return_statements_t, data.return_statements);
+ VEC_truncate (return_statements_t,
+ data.return_statements,
+ VEC_length (return_statements_t,
+ data.return_statements) - 1);
+
+ x = gimple_build_label (t.label);
+ gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
+ gsi_insert_after (&i, t.stmt, GSI_CONTINUE_LINKING);
+ }
+
+ /* If the function calls __builtin_setjmp, we need to emit the computed
+ goto that will serve as the unique dispatcher for all the receivers. */
+ if (data.calls_builtin_setjmp)
+ {
+ tree disp_label, disp_var, arg;
+
+ /* Build 'DISP_LABEL:' and insert. */
+ disp_label = create_artificial_label (cfun->function_end_locus);
+ /* This mark will create forward edges from every call site. */
+ DECL_NONLOCAL (disp_label) = 1;
+ cfun->has_nonlocal_label = 1;
+ x = gimple_build_label (disp_label);
+ gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
+
+ /* Build 'DISP_VAR = __builtin_setjmp_dispatcher (DISP_LABEL);'
+ and insert. */
+ disp_var = create_tmp_var (ptr_type_node, "setjmpvar");
+ arg = build_addr (disp_label, current_function_decl);
+ t = builtin_decl_implicit (BUILT_IN_SETJMP_DISPATCHER);
+ x = gimple_build_call (t, 1, arg);
+ gimple_call_set_lhs (x, disp_var);
+
+ /* Build 'goto DISP_VAR;' and insert. */
+ gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
+ x = gimple_build_goto (disp_var);
+ gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
}
gcc_assert (data.block == DECL_INITIAL (current_function_decl));
= blocks_nreverse (BLOCK_SUBBLOCKS (data.block));
clear_block_marks (data.block);
+ VEC_free(return_statements_t, heap, data.return_statements);
+ return 0;
}
-struct tree_opt_pass pass_lower_cf =
+struct gimple_opt_pass pass_lower_cf =
{
+ {
+ GIMPLE_PASS,
"lower", /* name */
NULL, /* gate */
lower_function_body, /* execute */
NULL, /* sub */
NULL, /* next */
0, /* static_pass_number */
- 0, /* tv_id */
+ TV_NONE, /* tv_id */
PROP_gimple_any, /* properties_required */
PROP_gimple_lcf, /* properties_provided */
- PROP_gimple_any, /* properties_destroyed */
+ 0, /* properties_destroyed */
0, /* todo_flags_start */
- TODO_dump_func, /* todo_flags_finish */
- 0 /* letter */
+ 0 /* todo_flags_finish */
+ }
};
-/* Lowers the EXPR. Unlike gimplification the statements are not relowered
+
+/* Verify if the type of the argument matches that of the function
+ declaration. If we cannot verify this or there is a mismatch,
+ return false. */
+
+static bool
+gimple_check_call_args (gimple stmt, tree fndecl)
+{
+ tree parms, p;
+ unsigned int i, nargs;
+
+ /* Calls to internal functions always match their signature. */
+ if (gimple_call_internal_p (stmt))
+ return true;
+
+ nargs = gimple_call_num_args (stmt);
+
+ /* Get argument types for verification. */
+ if (fndecl)
+ parms = TYPE_ARG_TYPES (TREE_TYPE (fndecl));
+ else
+ parms = TYPE_ARG_TYPES (gimple_call_fntype (stmt));
+
+ /* Verify if the type of the argument matches that of the function
+ declaration. If we cannot verify this or there is a mismatch,
+ return false. */
+ if (fndecl && DECL_ARGUMENTS (fndecl))
+ {
+ for (i = 0, p = DECL_ARGUMENTS (fndecl);
+ i < nargs;
+ i++, p = DECL_CHAIN (p))
+ {
+ /* We cannot distinguish a varargs function from the case
+ of excess parameters, still deferring the inlining decision
+ to the callee is possible. */
+ if (!p)
+ break;
+ if (p == error_mark_node
+ || gimple_call_arg (stmt, i) == error_mark_node
+ || !fold_convertible_p (DECL_ARG_TYPE (p),
+ gimple_call_arg (stmt, i)))
+ return false;
+ }
+ }
+ else if (parms)
+ {
+ for (i = 0, p = parms; i < nargs; i++, p = TREE_CHAIN (p))
+ {
+ /* If this is a varargs function defer inlining decision
+ to callee. */
+ if (!p)
+ break;
+ if (TREE_VALUE (p) == error_mark_node
+ || gimple_call_arg (stmt, i) == error_mark_node
+ || TREE_CODE (TREE_VALUE (p)) == VOID_TYPE
+ || !fold_convertible_p (TREE_VALUE (p),
+ gimple_call_arg (stmt, i)))
+ return false;
+ }
+ }
+ else
+ {
+ if (nargs != 0)
+ return false;
+ }
+ return true;
+}
+
+/* Verify if the type of the argument and lhs of CALL_STMT matches
+ that of the function declaration CALLEE.
+ If we cannot verify this or there is a mismatch, return false. */
+
+bool
+gimple_check_call_matching_types (gimple call_stmt, tree callee)
+{
+ tree lhs;
+
+ if ((DECL_RESULT (callee)
+ && !DECL_BY_REFERENCE (DECL_RESULT (callee))
+ && (lhs = gimple_call_lhs (call_stmt)) != NULL_TREE
+ && !useless_type_conversion_p (TREE_TYPE (DECL_RESULT (callee)),
+ TREE_TYPE (lhs))
+ && !fold_convertible_p (TREE_TYPE (DECL_RESULT (callee)), lhs))
+ || !gimple_check_call_args (call_stmt, callee))
+ return false;
+ return true;
+}
+
+/* Lower sequence SEQ. Unlike gimplification the statements are not relowered
when they are changed -- if this has to be done, the lowering routine must
do it explicitly. DATA is passed through the recursion. */
-void
-lower_stmt_body (tree expr, struct lower_data *data)
+static void
+lower_sequence (gimple_seq seq, struct lower_data *data)
+{
+ gimple_stmt_iterator gsi;
+
+ for (gsi = gsi_start (seq); !gsi_end_p (gsi); )
+ lower_stmt (&gsi, data);
+}
+
+
+/* Lower the OpenMP directive statement pointed by GSI. DATA is
+ passed through the recursion. */
+
+static void
+lower_omp_directive (gimple_stmt_iterator *gsi, struct lower_data *data)
{
- tree_stmt_iterator tsi;
+ gimple stmt;
+
+ stmt = gsi_stmt (*gsi);
- for (tsi = tsi_start (expr); !tsi_end_p (tsi); )
- lower_stmt (&tsi, data);
+ lower_sequence (gimple_omp_body (stmt), data);
+ gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
+ gsi_insert_seq_before (gsi, gimple_omp_body (stmt), GSI_SAME_STMT);
+ gimple_omp_set_body (stmt, NULL);
+ gsi_remove (gsi, false);
}
-/* Lowers statement TSI. DATA is passed through the recursion. */
+
+/* Lower statement GSI. DATA is passed through the recursion. We try to
+ track the fallthruness of statements and get rid of unreachable return
+ statements in order to prevent the EH lowering pass from adding useless
+ edges that can cause bogus warnings to be issued later; this guess need
+ not be 100% accurate, simply be conservative and reset cannot_fallthru
+ to false if we don't know. */
static void
-lower_stmt (tree_stmt_iterator *tsi, struct lower_data *data)
+lower_stmt (gimple_stmt_iterator *gsi, struct lower_data *data)
{
- tree stmt = tsi_stmt (*tsi);
+ gimple stmt = gsi_stmt (*gsi);
- if (EXPR_HAS_LOCATION (stmt) && data)
- TREE_BLOCK (stmt) = data->block;
+ gimple_set_block (stmt, data->block);
- switch (TREE_CODE (stmt))
+ switch (gimple_code (stmt))
{
- case BIND_EXPR:
- lower_bind_expr (tsi, data);
+ case GIMPLE_BIND:
+ lower_gimple_bind (gsi, data);
+ /* Propagate fallthruness. */
return;
- case COND_EXPR:
- lower_cond_expr (tsi, data);
+
+ case GIMPLE_COND:
+ case GIMPLE_GOTO:
+ case GIMPLE_SWITCH:
+ data->cannot_fallthru = true;
+ gsi_next (gsi);
return;
- case RETURN_EXPR:
- lower_return_expr (tsi, data);
+
+ case GIMPLE_RETURN:
+ if (data->cannot_fallthru)
+ {
+ gsi_remove (gsi, false);
+ /* Propagate fallthruness. */
+ }
+ else
+ {
+ lower_gimple_return (gsi, data);
+ data->cannot_fallthru = true;
+ }
return;
- case TRY_FINALLY_EXPR:
- case TRY_CATCH_EXPR:
- lower_stmt_body (TREE_OPERAND (stmt, 0), data);
- lower_stmt_body (TREE_OPERAND (stmt, 1), data);
+ case GIMPLE_TRY:
+ {
+ bool try_cannot_fallthru;
+ lower_sequence (gimple_try_eval (stmt), data);
+ try_cannot_fallthru = data->cannot_fallthru;
+ data->cannot_fallthru = false;
+ lower_sequence (gimple_try_cleanup (stmt), data);
+ /* See gimple_stmt_may_fallthru for the rationale. */
+ if (gimple_try_kind (stmt) == GIMPLE_TRY_FINALLY)
+ {
+ data->cannot_fallthru |= try_cannot_fallthru;
+ gsi_next (gsi);
+ return;
+ }
+ }
break;
- case CATCH_EXPR:
- lower_stmt_body (CATCH_BODY (stmt), data);
+
+ case GIMPLE_CATCH:
+ data->cannot_fallthru = false;
+ lower_sequence (gimple_catch_handler (stmt), data);
break;
- case EH_FILTER_EXPR:
- lower_stmt_body (EH_FILTER_FAILURE (stmt), data);
+
+ case GIMPLE_EH_FILTER:
+ data->cannot_fallthru = false;
+ lower_sequence (gimple_eh_filter_failure (stmt), data);
break;
-
- case NOP_EXPR:
- case ASM_EXPR:
- case MODIFY_EXPR:
- case CALL_EXPR:
- case GOTO_EXPR:
- case LABEL_EXPR:
- case SWITCH_EXPR:
+
+ case GIMPLE_EH_ELSE:
+ lower_sequence (gimple_eh_else_n_body (stmt), data);
+ lower_sequence (gimple_eh_else_e_body (stmt), data);
+ break;
+
+ case GIMPLE_NOP:
+ case GIMPLE_ASM:
+ case GIMPLE_ASSIGN:
+ case GIMPLE_PREDICT:
+ case GIMPLE_LABEL:
+ case GIMPLE_EH_MUST_NOT_THROW:
+ case GIMPLE_OMP_FOR:
+ case GIMPLE_OMP_SECTIONS:
+ case GIMPLE_OMP_SECTIONS_SWITCH:
+ case GIMPLE_OMP_SECTION:
+ case GIMPLE_OMP_SINGLE:
+ case GIMPLE_OMP_MASTER:
+ case GIMPLE_OMP_ORDERED:
+ case GIMPLE_OMP_CRITICAL:
+ case GIMPLE_OMP_RETURN:
+ case GIMPLE_OMP_ATOMIC_LOAD:
+ case GIMPLE_OMP_ATOMIC_STORE:
+ case GIMPLE_OMP_CONTINUE:
+ break;
+
+ case GIMPLE_CALL:
+ {
+ tree decl = gimple_call_fndecl (stmt);
+
+ if (decl
+ && DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL
+ && DECL_FUNCTION_CODE (decl) == BUILT_IN_SETJMP)
+ {
+ lower_builtin_setjmp (gsi);
+ data->cannot_fallthru = false;
+ data->calls_builtin_setjmp = true;
+ return;
+ }
+
+ if (decl && (flags_from_decl_or_type (decl) & ECF_NORETURN))
+ {
+ data->cannot_fallthru = true;
+ gsi_next (gsi);
+ return;
+ }
+ }
+ break;
+
+ case GIMPLE_OMP_PARALLEL:
+ case GIMPLE_OMP_TASK:
+ data->cannot_fallthru = false;
+ lower_omp_directive (gsi, data);
+ data->cannot_fallthru = false;
+ return;
+
+ case GIMPLE_TRANSACTION:
+ lower_sequence (gimple_transaction_body (stmt), data);
break;
default:
-#ifdef ENABLE_CHECKING
- print_node_brief (stderr, "", stmt, 0);
- internal_error ("unexpected node");
-#endif
- case COMPOUND_EXPR:
gcc_unreachable ();
}
- tsi_next (tsi);
+ data->cannot_fallthru = false;
+ gsi_next (gsi);
}
-/* Lowers a bind_expr TSI. DATA is passed through the recursion. */
+/* Lower a bind_expr TSI. DATA is passed through the recursion. */
static void
-lower_bind_expr (tree_stmt_iterator *tsi, struct lower_data *data)
+lower_gimple_bind (gimple_stmt_iterator *gsi, struct lower_data *data)
{
tree old_block = data->block;
- tree stmt = tsi_stmt (*tsi);
- tree new_block = BIND_EXPR_BLOCK (stmt);
+ gimple stmt = gsi_stmt (*gsi);
+ tree new_block = gimple_bind_block (stmt);
if (new_block)
{
}
}
- record_vars (BIND_EXPR_VARS (stmt));
- lower_stmt_body (BIND_EXPR_BODY (stmt), data);
+ record_vars (gimple_bind_vars (stmt));
+ lower_sequence (gimple_bind_body (stmt), data);
if (new_block)
{
data->block = old_block;
}
- /* The BIND_EXPR no longer carries any useful information -- kill it. */
- tsi_link_before (tsi, BIND_EXPR_BODY (stmt), TSI_SAME_STMT);
- tsi_delink (tsi);
+ /* 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 (tree block)
+block_may_fallthru (const_tree block)
{
- tree stmt = expr_last (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:
- case RESX_EXPR:
- /* Easy cases. If the last statement of the block implies
+ /* Easy cases. If the last statement of the block implies
control transfer, then we can't fall through. */
return false;
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;
+ return SWITCH_LABELS (stmt) == NULL_TREE;
case COND_EXPR:
if (block_may_fallthru (COND_EXPR_THEN (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:
- return block_may_fallthru (TREE_OPERAND (stmt, 1));
+ /* 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)
/* 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;
}
}
-/* Lowers a cond_expr TSI. DATA is passed through the recursion. */
-static void
-lower_cond_expr (tree_stmt_iterator *tsi, struct lower_data *data)
+/* 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)
{
- tree stmt = tsi_stmt (*tsi);
- bool then_is_goto, else_is_goto;
- tree then_branch, else_branch;
- tree then_goto, else_goto;
-
- then_branch = COND_EXPR_THEN (stmt);
- else_branch = COND_EXPR_ELSE (stmt);
+ if (!stmt)
+ return true;
- lower_stmt_body (then_branch, data);
- lower_stmt_body (else_branch, data);
+ 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;
- then_goto = expr_only (then_branch);
- then_is_goto = then_goto && simple_goto_p (then_goto);
+ case GIMPLE_SWITCH:
+ /* Switch has already been lowered and represents a branch
+ to a selected label and hence can't fall through. */
+ return false;
- else_goto = expr_only (else_branch);
- else_is_goto = else_goto && simple_goto_p (else_goto);
+ case GIMPLE_COND:
+ /* GIMPLE_COND's are already lowered into a two-way branch. They
+ can't fall through. */
+ return false;
- if (!then_is_goto || !else_is_goto)
- {
- tree then_label, else_label, end_label, t;
-
- then_label = NULL_TREE;
- else_label = NULL_TREE;
- end_label = NULL_TREE;
-
- /* Replace the cond_expr with explicit gotos. */
- if (!then_is_goto)
- {
- t = build1 (LABEL_EXPR, void_type_node, NULL_TREE);
- if (TREE_SIDE_EFFECTS (then_branch))
- then_label = t;
- else
- end_label = t;
- then_goto = build_and_jump (&LABEL_EXPR_LABEL (t));
- }
+ case GIMPLE_BIND:
+ return gimple_seq_may_fallthru (gimple_bind_body (stmt));
- if (!else_is_goto)
- {
- t = build1 (LABEL_EXPR, void_type_node, NULL_TREE);
- if (TREE_SIDE_EFFECTS (else_branch))
- else_label = t;
- else
- {
- /* Both THEN and ELSE can be no-ops if one or both contained an
- empty BIND_EXPR that was associated with the toplevel block
- of an inlined function. In that case remove_useless_stmts
- can't have cleaned things up for us; kill the whole
- conditional now. */
- if (end_label)
- {
- tsi_delink (tsi);
- return;
- }
- else
- end_label = t;
- }
- else_goto = build_and_jump (&LABEL_EXPR_LABEL (t));
- }
+ case GIMPLE_TRY:
+ if (gimple_try_kind (stmt) == GIMPLE_TRY_CATCH)
+ return gimple_try_catch_may_fallthru (stmt);
- if (then_label)
- {
- bool may_fallthru = block_may_fallthru (then_branch);
-
- tsi_link_after (tsi, then_label, TSI_CONTINUE_LINKING);
- tsi_link_after (tsi, then_branch, TSI_CONTINUE_LINKING);
-
- if (else_label && may_fallthru)
- {
- end_label = build1 (LABEL_EXPR, void_type_node, NULL_TREE);
- t = build_and_jump (&LABEL_EXPR_LABEL (end_label));
- tsi_link_after (tsi, t, TSI_CONTINUE_LINKING);
- }
- }
-
- if (else_label)
- {
- tsi_link_after (tsi, else_label, TSI_CONTINUE_LINKING);
- tsi_link_after (tsi, else_branch, TSI_CONTINUE_LINKING);
- }
+ /* 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_EH_ELSE:
+ return (gimple_seq_may_fallthru (gimple_eh_else_n_body (stmt))
+ || gimple_seq_may_fallthru (gimple_eh_else_e_body (stmt)));
+
+ case GIMPLE_CALL:
+ /* Functions that do not return do not fall through. */
+ return (gimple_call_flags (stmt) & ECF_NORETURN) == 0;
- if (end_label)
- tsi_link_after (tsi, end_label, TSI_CONTINUE_LINKING);
+ default:
+ return true;
}
+}
+
- COND_EXPR_THEN (stmt) = then_goto;
- COND_EXPR_ELSE (stmt) = else_goto;
+/* Same as gimple_stmt_may_fallthru, but for the gimple sequence SEQ. */
- tsi_next (tsi);
+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_return_expr (tree_stmt_iterator *tsi, struct lower_data *data)
+lower_gimple_return (gimple_stmt_iterator *gsi, struct lower_data *data)
{
- tree stmt = tsi_stmt (*tsi);
- tree value, t, label;
-
- /* Extract the value being returned. */
- value = TREE_OPERAND (stmt, 0);
- if (value && TREE_CODE (value) == MODIFY_EXPR)
- value = TREE_OPERAND (value, 1);
+ 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 (t = data->return_statements; t ; t = TREE_CHAIN (t))
+ for (i = VEC_length (return_statements_t, data->return_statements) - 1;
+ i >= 0; i--)
{
- tree tvalue = TREE_OPERAND (TREE_VALUE (t), 0);
- if (tvalue && TREE_CODE (tvalue) == MODIFY_EXPR)
- tvalue = TREE_OPERAND (tvalue, 1);
+ tmp_rs = *VEC_index (return_statements_t, data->return_statements, i);
- if (value == tvalue)
+ if (gimple_return_retval (stmt) == gimple_return_retval (tmp_rs.stmt))
{
- label = TREE_PURPOSE (t);
+ /* 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. */
- label = create_artificial_label ();
- data->return_statements = tree_cons (label, stmt, data->return_statements);
+ 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:
- t = build (GOTO_EXPR, void_type_node, label);
- SET_EXPR_LOCUS (t, EXPR_LOCUS (stmt));
- tsi_link_before (tsi, t, TSI_SAME_STMT);
- tsi_delink (tsi);
+ /* 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);
}
-\f
-/* Record the variables in VARS. */
+/* Lower a __builtin_setjmp GSI.
-void
-record_vars (tree vars)
-{
- for (; vars; vars = TREE_CHAIN (vars))
- {
- tree var = vars;
+ __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.
- /* Nothing to do in this case. */
- if (DECL_EXTERNAL (var))
- continue;
- if (TREE_CODE (var) == FUNCTION_DECL)
- continue;
+ 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.
- /* Record the variable. */
- cfun->unexpanded_var_list = tree_cons (NULL_TREE, var,
- cfun->unexpanded_var_list);
+ 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;
}
-}
-/* Check whether to expand a variable VAR. */
+ 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 bool
-expand_var_p (tree var)
+static void
+lower_builtin_setjmp (gimple_stmt_iterator *gsi)
{
- struct var_ann_d *ann;
+ 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 = builtin_decl_implicit (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);
+ }
- if (TREE_CODE (var) != VAR_DECL)
- return true;
+ /* Build 'goto CONT_LABEL' and insert. */
+ g = gimple_build_goto (cont_label);
+ gsi_insert_before (gsi, g, GSI_SAME_STMT);
- /* Leave statics and externals alone. */
- if (TREE_STATIC (var) || DECL_EXTERNAL (var))
- return true;
+ /* Build 'NEXT_LABEL:' and insert. */
+ g = gimple_build_label (next_label);
+ gsi_insert_before (gsi, g, GSI_SAME_STMT);
- /* Remove all unused local variables. */
- ann = var_ann (var);
- if (!ann || !ann->used)
- return false;
+ /* Build '__builtin_setjmp_receiver (NEXT_LABEL)' and insert. */
+ arg = build_addr (next_label, current_function_decl);
+ t = builtin_decl_implicit (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);
- return true;
+ /* 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);
}
+\f
-/* Throw away variables that are unused. */
+/* Record the variables in VARS into function FN. */
-static void
-remove_useless_vars (void)
+void
+record_vars_into (tree vars, tree fn)
{
- tree var, *cell;
- FILE *df = NULL;
+ if (fn != current_function_decl)
+ push_cfun (DECL_STRUCT_FUNCTION (fn));
- if (dump_file && (dump_flags & TDF_DETAILS))
+ for (; vars; vars = DECL_CHAIN (vars))
{
- df = dump_file;
- fputs ("Discarding as unused:\n", df);
- }
+ tree var = vars;
- for (cell = &cfun->unexpanded_var_list; *cell; )
- {
- var = TREE_VALUE (*cell);
+ /* BIND_EXPRs contains also function/type/constant declarations
+ we don't need to care about. */
+ if (TREE_CODE (var) != VAR_DECL)
+ continue;
- if (!expand_var_p (var))
- {
- if (df)
- {
- fputs (" ", df);
- print_generic_expr (df, var, dump_flags);
- fputc ('\n', df);
- }
-
- *cell = TREE_CHAIN (*cell);
- continue;
- }
+ /* Nothing to do in this case. */
+ if (DECL_EXTERNAL (var))
+ continue;
- cell = &TREE_CHAIN (*cell);
+ /* Record the variable. */
+ add_local_decl (cfun, var);
+ if (gimple_referenced_vars (cfun))
+ add_referenced_var (var);
}
- if (df)
- fputc ('\n', df);
+ if (fn != current_function_decl)
+ pop_cfun ();
}
-struct tree_opt_pass pass_remove_useless_vars =
-{
- "vars", /* name */
- NULL, /* gate */
- remove_useless_vars, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- 0, /* tv_id */
- 0, /* properties_required */
- 0, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- TODO_dump_func, /* todo_flags_finish */
- 0 /* letter */
-};
-/* Mark BLOCK used if it has a used variable in it, then recurse over its
- subblocks. */
+/* Record the variables in VARS into current_function_decl. */
-static void
-mark_blocks_with_used_vars (tree block)
+void
+record_vars (tree vars)
{
- tree var;
- tree subblock;
-
- if (!TREE_USED (block))
- {
- for (var = BLOCK_VARS (block);
- var;
- var = TREE_CHAIN (var))
- {
- if (TREE_USED (var))
- {
- TREE_USED (block) = true;
- break;
- }
- }
- }
- for (subblock = BLOCK_SUBBLOCKS (block);
- subblock;
- subblock = BLOCK_CHAIN (subblock))
- mark_blocks_with_used_vars (subblock);
-}
-
-/* Mark the used attribute on blocks correctly. */
-
-static void
-mark_used_blocks (void)
-{
- mark_blocks_with_used_vars (DECL_INITIAL (current_function_decl));
+ record_vars_into (vars, current_function_decl);
}
-
-
-struct tree_opt_pass pass_mark_used_blocks =
-{
- "blocks", /* name */
- NULL, /* gate */
- mark_used_blocks, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- 0, /* tv_id */
- 0, /* properties_required */
- 0, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- TODO_dump_func, /* todo_flags_finish */
- 0 /* letter */
-};
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