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trans.c (Loop_Statement_to_gnu): In the case of an iteration scheme...

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* gcc-interface/trans.c (Loop_Statement_to_gnu): In the case of an
	iteration scheme, always generate the do-while form if optimization
	is enabled.  Use more straightforward test at the end.

From-SVN: r179169
This commit is contained in:
Eric Botcazou 2011-09-25 20:27:37 +00:00 committed by Eric Botcazou
parent dee12fcd11
commit 6162cec0d9
2 changed files with 107 additions and 62 deletions
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6
gcc/ada/ChangeLog
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@ -1,3 +1,9 @@
2011-09-25 Eric Botcazou <ebotcazou@adacore.com>
* gcc-interface/trans.c (Loop_Statement_to_gnu): In the case of an
iteration scheme, always generate the do-while form if optimization
is enabled. Use more straightforward test at the end.
2011-09-25 Eric Botcazou <ebotcazou@adacore.com>
* gcc-interface/decl.c (gnat_to_gnu_entity) <E_Access_Subtype>: Use

163
gcc/ada/gcc-interface/trans.c
View File

@ -218,6 +218,7 @@ static bool set_end_locus_from_node (tree, Node_Id);
static void set_gnu_expr_location_from_node (tree, Node_Id);
static int lvalue_required_p (Node_Id, tree, bool, bool, bool);
static tree build_raise_check (int, enum exception_info_kind);
static tree create_init_temporary (const char *, tree, tree *, Node_Id);
/* Hooks for debug info back-ends, only supported and used in a restricted set
of configurations. */
@ -2161,8 +2162,7 @@ Loop_Statement_to_gnu (Node_Id gnat_node)
tree gnu_loop_stmt = build4 (LOOP_STMT, void_type_node, NULL_TREE,
NULL_TREE, NULL_TREE, NULL_TREE);
tree gnu_loop_label = create_artificial_label (input_location);
tree gnu_loop_var = NULL_TREE, gnu_cond_expr = NULL_TREE;
tree gnu_result;
tree gnu_cond_expr = NULL_TREE, gnu_result;
/* Set location information for statement and end label. */
set_expr_location_from_node (gnu_loop_stmt, gnat_node);
@ -2196,9 +2196,9 @@ Loop_Statement_to_gnu (Node_Id gnat_node)
tree gnu_high = TYPE_MAX_VALUE (gnu_type);
tree gnu_base_type = get_base_type (gnu_type);
tree gnu_one_node = convert (gnu_base_type, integer_one_node);
tree gnu_first, gnu_last;
tree gnu_loop_var, gnu_loop_iv, gnu_first, gnu_last, gnu_stmt;
enum tree_code update_code, test_code, shift_code;
bool reverse = Reverse_Present (gnat_loop_spec), fallback = false;
bool reverse = Reverse_Present (gnat_loop_spec), use_iv = false;
/* We must disable modulo reduction for the iteration variable, if any,
in order for the loop comparison to be effective. */
@ -2222,8 +2222,8 @@ Loop_Statement_to_gnu (Node_Id gnat_node)
/* We use two different strategies to translate the loop, depending on
whether optimization is enabled.
If it is, we try to generate the canonical form of loop expected by
the loop optimizer, which is the do-while form:
If it is, we generate the canonical loop form expected by the loop
optimizer and the loop vectorizer, which is the do-while form:
ENTRY_COND
loop:
@ -2232,10 +2232,12 @@ Loop_Statement_to_gnu (Node_Id gnat_node)
BOTTOM_COND
GOTO loop
This makes it possible to bypass loop header copying and to turn the
BOTTOM_COND into an inequality test. This should catch (almost) all
loops with constant starting point. If we cannot, we try to generate
the default form, which is:
This avoids an implicit dependency on loop header copying and makes
it possible to turn BOTTOM_COND into an inequality test.
If optimization is disabled, loop header copying doesn't come into
play and we try to generate the loop form with the fewer conditional
branches. First, the default form, which is:
loop:
TOP_COND
@ -2243,25 +2245,8 @@ Loop_Statement_to_gnu (Node_Id gnat_node)
BOTTOM_UPDATE
GOTO loop
It will be rotated during loop header copying and an entry test added
to yield the do-while form. This should catch (almost) all loops with
constant ending point. If we cannot, we generate the fallback form:
ENTRY_COND
loop:
BODY
BOTTOM_COND
BOTTOM_UPDATE
GOTO loop
which works in all cases but for which loop header copying will copy
the BOTTOM_COND, thus adding a third conditional branch.
If optimization is disabled, loop header copying doesn't come into
play and we try to generate the loop forms with the less conditional
branches directly. First, the default form, it should catch (almost)
all loops with constant ending point. Then, if we cannot, we try to
generate the shifted form:
It should catch most loops with constant ending point. Then, if we
cannot, we try to generate the shifted form:
loop:
TOP_COND
@ -2270,26 +2255,44 @@ Loop_Statement_to_gnu (Node_Id gnat_node)
GOTO loop
which should catch loops with constant starting point. Otherwise, if
we cannot, we generate the fallback form. */
we cannot, we generate the fallback form:
ENTRY_COND
loop:
BODY
BOTTOM_COND
BOTTOM_UPDATE
GOTO loop
which works in all cases. */
if (optimize)
{
/* We can use the do-while form if GNU_FIRST-1 doesn't overflow. */
/* We can use the do-while form directly if GNU_FIRST-1 doesn't
overflow. */
if (!can_equal_min_val_p (gnu_first, gnu_base_type, reverse))
{
gnu_first = build_binary_op (shift_code, gnu_base_type,
gnu_first, gnu_one_node);
LOOP_STMT_TOP_UPDATE_P (gnu_loop_stmt) = 1;
LOOP_STMT_BOTTOM_COND_P (gnu_loop_stmt) = 1;
}
/* Otherwise, we can use the default form if GNU_LAST+1 doesn't. */
else if (!can_equal_max_val_p (gnu_last, gnu_base_type, reverse))
;
/* Otherwise, use the fallback form. */
/* Otherwise, use the do-while form with the help of a special
induction variable in the (unsigned version of) the base
type, in order to have wrap-around arithmetics for it. */
else
fallback = true;
{
if (!TYPE_UNSIGNED (gnu_base_type))
{
gnu_base_type = gnat_unsigned_type (gnu_base_type);
gnu_first = convert (gnu_base_type, gnu_first);
gnu_last = convert (gnu_base_type, gnu_last);
gnu_one_node = convert (gnu_base_type, integer_one_node);
}
use_iv = true;
}
gnu_first
= build_binary_op (shift_code, gnu_base_type, gnu_first,
gnu_one_node);
LOOP_STMT_TOP_UPDATE_P (gnu_loop_stmt) = 1;
LOOP_STMT_BOTTOM_COND_P (gnu_loop_stmt) = 1;
}
else
{
@ -2302,21 +2305,20 @@ Loop_Statement_to_gnu (Node_Id gnat_node)
else if (!can_equal_min_val_p (gnu_first, gnu_base_type, reverse)
&& !can_equal_min_val_p (gnu_last, gnu_base_type, reverse))
{
gnu_first = build_binary_op (shift_code, gnu_base_type,
gnu_first, gnu_one_node);
gnu_last = build_binary_op (shift_code, gnu_base_type,
gnu_last, gnu_one_node);
gnu_first
= build_binary_op (shift_code, gnu_base_type, gnu_first,
gnu_one_node);
gnu_last
= build_binary_op (shift_code, gnu_base_type, gnu_last,
gnu_one_node);
LOOP_STMT_TOP_UPDATE_P (gnu_loop_stmt) = 1;
}
/* Otherwise, use the fallback form. */
else
fallback = true;
LOOP_STMT_BOTTOM_COND_P (gnu_loop_stmt) = 1;
}
if (fallback)
LOOP_STMT_BOTTOM_COND_P (gnu_loop_stmt) = 1;
/* If we use the BOTTOM_COND, we can turn the test into an inequality
test but we may have to add ENTRY_COND to protect the empty loop. */
if (LOOP_STMT_BOTTOM_COND_P (gnu_loop_stmt))
@ -2338,6 +2340,19 @@ Loop_Statement_to_gnu (Node_Id gnat_node)
start_stmt_group ();
gnat_pushlevel ();
/* If we use the special induction variable, create it and set it to
its initial value. Morever, the regular iteration variable cannot
itself be initialized, lest the initial value wrapped around. */
if (use_iv)
{
gnu_loop_iv
= create_init_temporary ("I", gnu_first, &gnu_stmt, gnat_loop_var);
add_stmt (gnu_stmt);
gnu_first = NULL_TREE;
}
else
gnu_loop_iv = NULL_TREE;
/* Declare the iteration variable and set it to its initial value. */
gnu_loop_var = gnat_to_gnu_entity (gnat_loop_var, gnu_first, 1);
if (DECL_BY_REF_P (gnu_loop_var))
@ -2347,18 +2362,42 @@ Loop_Statement_to_gnu (Node_Id gnat_node)
gnu_loop_var = convert (gnu_base_type, gnu_loop_var);
/* Set either the top or bottom exit condition. */
LOOP_STMT_COND (gnu_loop_stmt)
= build_binary_op (test_code, boolean_type_node, gnu_loop_var,
gnu_last);
if (use_iv)
LOOP_STMT_COND (gnu_loop_stmt)
= build_binary_op (test_code, boolean_type_node, gnu_loop_iv,
gnu_last);
else
LOOP_STMT_COND (gnu_loop_stmt)
= build_binary_op (test_code, boolean_type_node, gnu_loop_var,
gnu_last);
/* Set either the top or bottom update statement and give it the source
location of the iteration for better coverage info. */
LOOP_STMT_UPDATE (gnu_loop_stmt)
= build_binary_op (MODIFY_EXPR, NULL_TREE, gnu_loop_var,
build_binary_op (update_code, gnu_base_type,
gnu_loop_var, gnu_one_node));
set_expr_location_from_node (LOOP_STMT_UPDATE (gnu_loop_stmt),
gnat_iter_scheme);
if (use_iv)
{
gnu_stmt
= build_binary_op (MODIFY_EXPR, NULL_TREE, gnu_loop_iv,
build_binary_op (update_code, gnu_base_type,
gnu_loop_iv, gnu_one_node));
set_expr_location_from_node (gnu_stmt, gnat_iter_scheme);
append_to_statement_list (gnu_stmt,
&LOOP_STMT_UPDATE (gnu_loop_stmt));
gnu_stmt
= build_binary_op (MODIFY_EXPR, NULL_TREE, gnu_loop_var,
gnu_loop_iv);
set_expr_location_from_node (gnu_stmt, gnat_iter_scheme);
append_to_statement_list (gnu_stmt,
&LOOP_STMT_UPDATE (gnu_loop_stmt));
}
else
{
gnu_stmt
= build_binary_op (MODIFY_EXPR, NULL_TREE, gnu_loop_var,
build_binary_op (update_code, gnu_base_type,
gnu_loop_var, gnu_one_node));
set_expr_location_from_node (gnu_stmt, gnat_iter_scheme);
LOOP_STMT_UPDATE (gnu_loop_stmt) = gnu_stmt;
}
}
/* If the loop was named, have the name point to this loop. In this case,
@ -2372,9 +2411,9 @@ Loop_Statement_to_gnu (Node_Id gnat_node)
= build_stmt_group (Statements (gnat_node), true);
TREE_SIDE_EFFECTS (gnu_loop_stmt) = 1;
/* If we declared a variable, then we are in a statement group for that
declaration. Add the LOOP_STMT to it and make that the "loop". */
if (gnu_loop_var)
/* If we have an iteration scheme, then we are in a statement group. Add
the LOOP_STMT to it, finish it and make it the "loop". */
if (Present (gnat_iter_scheme) && No (Condition (gnat_iter_scheme)))
{
add_stmt (gnu_loop_stmt);
gnat_poplevel ();