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_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;
default:
return true;
}
}
static bool
gimple_try_catch_may_fallthru (gtry *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_ptr (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 (
as_a <gcatch *> (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;
}
}
static unsigned int
lower_function_body (void)
{
struct lower_data data;
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.create (8);
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);
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 vector, we don't
need to do anything special. Otherwise build one by hand. */
if (gimple_seq_may_fallthru (lowered_body)
&& (data.return_statements.is_empty ()
|| gimple_return_retval (data.return_statements.last().stmt) != NULL))
{
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. */
while (!data.return_statements.is_empty ())
{
return_statements_t t = data.return_statements.pop ();
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);
}
/* Once the old body has been lowered, replace it with the new
lowered sequence. */
gimple_set_body (current_function_decl, lowered_body);
gcc_assert (data.block == DECL_INITIAL (current_function_decl));
BLOCK_SUBBLOCKS (data.block)
= blocks_nreverse (BLOCK_SUBBLOCKS (data.block));
clear_block_marks (data.block);
data.return_statements.release ();
return 0;
}
static unsigned int
lower_function_body (void)
{
struct lower_data data;
gimple_seq body = gimple_body (current_function_decl);
gimple_seq lowered_body;
gimple_stmt_iterator i;
gimple bind;
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.create (8);
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);
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 vector, we don't
need to do anything special. Otherwise build one by hand. */
if (gimple_seq_may_fallthru (lowered_body)
&& (data.return_statements.is_empty ()
|| (gimple_return_retval (data.return_statements.last().stmt)
!= NULL)))
{
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. */
while (!data.return_statements.is_empty ())
{
return_statements_t t = data.return_statements.pop ();
x = gimple_build_label (t.label);
gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
gsi_insert_after (&i, t.stmt, GSI_CONTINUE_LINKING);
}
/* Once the old body has been lowered, replace it with the new
lowered sequence. */
gimple_set_body (current_function_decl, lowered_body);
gcc_assert (data.block == DECL_INITIAL (current_function_decl));
BLOCK_SUBBLOCKS (data.block)
= blocks_nreverse (BLOCK_SUBBLOCKS (data.block));
clear_block_marks (data.block);
data.return_statements.release ();
return 0;
}
static unsigned int
lower_function_body (void)
{
struct lower_data data;
gimple_seq body = gimple_body (current_function_decl);
gimple_seq lowered_body;
gimple_stmt_iterator i;
gimple *bind;
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.create (8);
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);
i = gsi_last (lowered_body);
/* If we had begin stmt markers from e.g. PCH, but this compilation
doesn't want them, lower_stmt will have cleaned them up; we can
now clear the flag that indicates we had them. */
if (!MAY_HAVE_DEBUG_MARKER_STMTS && cfun->debug_nonbind_markers)
{
/* This counter needs not be exact, but before lowering it will
most certainly be. */
gcc_assert (cfun->debug_marker_count == 0);
cfun->debug_nonbind_markers = false;
}
/* If the function falls off the end, we need a null return statement.
If we've already got one in the return_statements vector, we don't
need to do anything special. Otherwise build one by hand. */
bool may_fallthru = gimple_seq_may_fallthru (lowered_body);
if (may_fallthru
&& (data.return_statements.is_empty ()
|| (gimple_return_retval (data.return_statements.last().stmt)
!= NULL)))
{
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);
may_fallthru = false;
}
/* If we lowered any return statements, emit the representative
at the end of the function. */
while (!data.return_statements.is_empty ())
{
return_statements_t t = data.return_statements.pop ();
x = gimple_build_label (t.label);
gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
gsi_insert_after (&i, t.stmt, GSI_CONTINUE_LINKING);
if (may_fallthru)
{
/* Remove the line number from the representative return statement.
It now fills in for the fallthru too. Failure to remove this
will result in incorrect results for coverage analysis. */
gimple_set_location (t.stmt, UNKNOWN_LOCATION);
may_fallthru = false;
}
}
/* Once the old body has been lowered, replace it with the new
lowered sequence. */
gimple_set_body (current_function_decl, lowered_body);
gcc_assert (data.block == DECL_INITIAL (current_function_decl));
BLOCK_SUBBLOCKS (data.block)
= blocks_nreverse (BLOCK_SUBBLOCKS (data.block));
clear_block_marks (data.block);
data.return_statements.release ();
return 0;
}
