605 lines
16 KiB
C
605 lines
16 KiB
C
/* Build expressions with type checking for C compiler.
|
||
Copyright (C) 1987, 88, 89, 92-97, 1998 Free Software Foundation, Inc.
|
||
|
||
This file is part of GNU CC.
|
||
|
||
GNU CC 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 version.
|
||
|
||
GNU CC is distributed in the hope that it will be useful,
|
||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
GNU General Public License for more details.
|
||
|
||
You should have received a copy of the GNU General Public License
|
||
along with GNU CC; see the file COPYING. If not, write to
|
||
the Free Software Foundation, 59 Temple Place - Suite 330,
|
||
Boston, MA 02111-1307, USA. */
|
||
|
||
|
||
/* This file is part of the C front end.
|
||
It is responsible for implementing iterators,
|
||
both their declarations and the expansion of statements using them. */
|
||
|
||
#include "config.h"
|
||
#include "system.h"
|
||
#include "tree.h"
|
||
#include "c-tree.h"
|
||
#include "flags.h"
|
||
#include "obstack.h"
|
||
#include "rtl.h"
|
||
#include "toplev.h"
|
||
#include "expr.h"
|
||
|
||
/*
|
||
KEEPING TRACK OF EXPANSIONS
|
||
|
||
In order to clean out expansions corresponding to statements inside
|
||
"{(...)}" constructs we have to keep track of all expansions. The
|
||
cleanup is needed when an automatic, or implicit, expansion on
|
||
iterator, say X, happens to a statement which contains a {(...)}
|
||
form with a statement already expanded on X. In this case we have
|
||
to go back and cleanup the inner expansion. This can be further
|
||
complicated by the fact that {(...)} can be nested.
|
||
|
||
To make this cleanup possible, we keep lists of all expansions, and
|
||
to make it work for nested constructs, we keep a stack. The list at
|
||
the top of the stack (ITER_STACK.CURRENT_LEVEL) corresponds to the
|
||
currently parsed level. All expansions of the levels below the
|
||
current one are kept in one list whose head is pointed to by
|
||
ITER_STACK.SUBLEVEL_FIRST (SUBLEVEL_LAST is there for making merges
|
||
easy). The process works as follows:
|
||
|
||
-- On "({" a new node is added to the stack by PUSH_ITERATOR_STACK.
|
||
The sublevel list is not changed at this point.
|
||
|
||
-- On "})" the list for the current level is appended to the sublevel
|
||
list.
|
||
|
||
-- On ";" sublevel lists are appended to the current level lists.
|
||
The reason is this: if they have not been superseded by the
|
||
expansion at the current level, they still might be
|
||
superseded later by the expansion on the higher level.
|
||
The levels do not have to distinguish levels below, so we
|
||
can merge the lists together. */
|
||
|
||
struct ixpansion
|
||
{
|
||
tree ixdecl; /* Iterator decl */
|
||
rtx ixprologue_start; /* First insn of epilogue. NULL means */
|
||
/* explicit (FOR) expansion*/
|
||
rtx ixprologue_end;
|
||
rtx ixepilogue_start;
|
||
rtx ixepilogue_end;
|
||
struct ixpansion *next; /* Next in the list */
|
||
};
|
||
|
||
struct iter_stack_node
|
||
{
|
||
struct ixpansion *first; /* Head of list of ixpansions */
|
||
struct ixpansion *last; /* Last node in list of ixpansions */
|
||
struct iter_stack_node *next; /* Next level iterator stack node */
|
||
};
|
||
|
||
struct iter_stack_node *iter_stack;
|
||
struct iter_stack_node sublevel_ixpansions;
|
||
|
||
/* A special obstack, and a pointer to the start of
|
||
all the data in it (so we can free everything easily). */
|
||
static struct obstack ixp_obstack;
|
||
static char *ixp_firstobj;
|
||
|
||
/* During collect_iterators, a list of SAVE_EXPRs already scanned. */
|
||
static tree save_exprs;
|
||
|
||
static void expand_stmt_with_iterators_1 PROTO((tree, tree));
|
||
static tree collect_iterators PROTO((tree, tree));
|
||
static void iterator_loop_prologue PROTO((tree, rtx *, rtx *));
|
||
static void iterator_loop_epilogue PROTO((tree, rtx *, rtx *));
|
||
static int top_level_ixpansion_p PROTO((void));
|
||
static void isn_append PROTO((struct iter_stack_node *,
|
||
struct iter_stack_node *));
|
||
static void istack_sublevel_to_current PROTO((void));
|
||
static void add_ixpansion PROTO((tree, rtx, rtx, rtx, rtx));
|
||
static void delete_ixpansion PROTO((tree));
|
||
|
||
/* Initialize our obstack once per compilation. */
|
||
|
||
void
|
||
init_iterators ()
|
||
{
|
||
gcc_obstack_init (&ixp_obstack);
|
||
ixp_firstobj = (char *) obstack_alloc (&ixp_obstack, 0);
|
||
}
|
||
|
||
/* Handle the start of an explicit `for' loop for iterator IDECL. */
|
||
|
||
void
|
||
iterator_for_loop_start (idecl)
|
||
tree idecl;
|
||
{
|
||
ITERATOR_BOUND_P (idecl) = 1;
|
||
add_ixpansion (idecl, 0, 0, 0, 0);
|
||
iterator_loop_prologue (idecl, 0, 0);
|
||
}
|
||
|
||
/* Handle the end of an explicit `for' loop for iterator IDECL. */
|
||
|
||
void
|
||
iterator_for_loop_end (idecl)
|
||
tree idecl;
|
||
{
|
||
iterator_loop_epilogue (idecl, 0, 0);
|
||
ITERATOR_BOUND_P (idecl) = 0;
|
||
}
|
||
|
||
/*
|
||
ITERATOR RTL EXPANSIONS
|
||
|
||
Expanding simple statements with iterators is straightforward:
|
||
collect the list of all free iterators in the statement, and
|
||
generate a loop for each of them.
|
||
|
||
An iterator is "free" if it has not been "bound" by a FOR
|
||
operator. The DECL_RTL of the iterator is the loop counter. */
|
||
|
||
/* Expand a statement STMT, possibly containing iterator usage, into RTL. */
|
||
|
||
void
|
||
iterator_expand (stmt)
|
||
tree stmt;
|
||
{
|
||
tree iter_list;
|
||
save_exprs = NULL_TREE;
|
||
iter_list = collect_iterators (stmt, NULL_TREE);
|
||
expand_stmt_with_iterators_1 (stmt, iter_list);
|
||
istack_sublevel_to_current ();
|
||
}
|
||
|
||
|
||
static void
|
||
expand_stmt_with_iterators_1 (stmt, iter_list)
|
||
tree stmt, iter_list;
|
||
{
|
||
if (iter_list == 0)
|
||
expand_expr_stmt (stmt);
|
||
else
|
||
{
|
||
tree current_iterator = TREE_VALUE (iter_list);
|
||
tree iter_list_tail = TREE_CHAIN (iter_list);
|
||
rtx p_start, p_end, e_start, e_end;
|
||
|
||
iterator_loop_prologue (current_iterator, &p_start, &p_end);
|
||
expand_stmt_with_iterators_1 (stmt, iter_list_tail);
|
||
iterator_loop_epilogue (current_iterator, &e_start, &e_end);
|
||
|
||
/** Delete all inner expansions based on current_iterator **/
|
||
/** before adding the outer one. **/
|
||
|
||
delete_ixpansion (current_iterator);
|
||
add_ixpansion (current_iterator, p_start, p_end, e_start, e_end);
|
||
}
|
||
}
|
||
|
||
|
||
/* Return a list containing all the free (i.e. not bound by a
|
||
containing `for' statement) iterators mentioned in EXP, plus those
|
||
in LIST. Do not add duplicate entries to the list. */
|
||
|
||
static tree
|
||
collect_iterators (exp, list)
|
||
tree exp, list;
|
||
{
|
||
if (exp == 0) return list;
|
||
|
||
switch (TREE_CODE (exp))
|
||
{
|
||
case VAR_DECL:
|
||
if (! ITERATOR_P (exp) || ITERATOR_BOUND_P (exp))
|
||
return list;
|
||
if (value_member (exp, list))
|
||
return list;
|
||
return tree_cons (NULL_TREE, exp, list);
|
||
|
||
case TREE_LIST:
|
||
{
|
||
tree tail;
|
||
for (tail = exp; tail; tail = TREE_CHAIN (tail))
|
||
list = collect_iterators (TREE_VALUE (tail), list);
|
||
return list;
|
||
}
|
||
|
||
case SAVE_EXPR:
|
||
/* In each scan, scan a given save_expr only once. */
|
||
if (value_member (exp, save_exprs))
|
||
return list;
|
||
|
||
save_exprs = tree_cons (NULL_TREE, exp, save_exprs);
|
||
return collect_iterators (TREE_OPERAND (exp, 0), list);
|
||
|
||
/* we do not automatically iterate blocks -- one must */
|
||
/* use the FOR construct to do that */
|
||
|
||
case BLOCK:
|
||
return list;
|
||
|
||
default:
|
||
switch (TREE_CODE_CLASS (TREE_CODE (exp)))
|
||
{
|
||
case '1':
|
||
return collect_iterators (TREE_OPERAND (exp, 0), list);
|
||
|
||
case '2':
|
||
case '<':
|
||
return collect_iterators (TREE_OPERAND (exp, 0),
|
||
collect_iterators (TREE_OPERAND (exp, 1),
|
||
list));
|
||
|
||
case 'e':
|
||
case 'r':
|
||
{
|
||
int num_args = tree_code_length[(int) TREE_CODE (exp)];
|
||
int i;
|
||
|
||
/* Some tree codes have RTL, not trees, as operands. */
|
||
switch (TREE_CODE (exp))
|
||
{
|
||
case CALL_EXPR:
|
||
num_args = 2;
|
||
break;
|
||
case METHOD_CALL_EXPR:
|
||
num_args = 3;
|
||
break;
|
||
case WITH_CLEANUP_EXPR:
|
||
num_args = 1;
|
||
break;
|
||
case RTL_EXPR:
|
||
return list;
|
||
default:
|
||
break;
|
||
}
|
||
|
||
for (i = 0; i < num_args; i++)
|
||
list = collect_iterators (TREE_OPERAND (exp, i), list);
|
||
return list;
|
||
}
|
||
default:
|
||
return list;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Emit rtl for the start of a loop for iterator IDECL.
|
||
|
||
If necessary, create loop counter rtx and store it as DECL_RTL of IDECL.
|
||
|
||
The prologue normally starts and ends with notes, which are returned
|
||
by this function in *START_NOTE and *END_NODE.
|
||
If START_NOTE and END_NODE are 0, we don't make those notes. */
|
||
|
||
static void
|
||
iterator_loop_prologue (idecl, start_note, end_note)
|
||
tree idecl;
|
||
rtx *start_note, *end_note;
|
||
{
|
||
tree expr;
|
||
|
||
/* Force the save_expr in DECL_INITIAL to be calculated
|
||
if it hasn't been calculated yet. */
|
||
expand_expr (DECL_INITIAL (idecl), const0_rtx, VOIDmode,
|
||
EXPAND_NORMAL);
|
||
|
||
if (DECL_RTL (idecl) == 0)
|
||
expand_decl (idecl);
|
||
|
||
if (start_note)
|
||
*start_note = emit_note (0, NOTE_INSN_DELETED);
|
||
|
||
/* Initialize counter. */
|
||
expr = build (MODIFY_EXPR, TREE_TYPE (idecl), idecl, integer_zero_node);
|
||
TREE_SIDE_EFFECTS (expr) = 1;
|
||
expand_expr (expr, const0_rtx, VOIDmode, EXPAND_NORMAL);
|
||
|
||
expand_start_loop_continue_elsewhere (1);
|
||
|
||
ITERATOR_BOUND_P (idecl) = 1;
|
||
|
||
if (end_note)
|
||
*end_note = emit_note (0, NOTE_INSN_DELETED);
|
||
}
|
||
|
||
/* Similar to the previous function, but for the end of the loop.
|
||
|
||
DECL_RTL is zeroed unless we are inside "({...})". The reason for that is
|
||
described below.
|
||
|
||
When we create two (or more) loops based on the same IDECL, and
|
||
both inside the same "({...})" construct, we must be prepared to
|
||
delete both of the loops and create a single one on the level
|
||
above, i.e. enclosing the "({...})". The new loop has to use the
|
||
same counter rtl because the references to the iterator decl
|
||
(IDECL) have already been expanded as references to the counter
|
||
rtl.
|
||
|
||
It is incorrect to use the same counter reg in different functions,
|
||
and it is desirable to use different counters in disjoint loops
|
||
when we know there's no need to combine them (because then they can
|
||
get allocated separately). */
|
||
|
||
static void
|
||
iterator_loop_epilogue (idecl, start_note, end_note)
|
||
tree idecl;
|
||
rtx *start_note, *end_note;
|
||
{
|
||
tree test, incr;
|
||
|
||
if (start_note)
|
||
*start_note = emit_note (0, NOTE_INSN_DELETED);
|
||
expand_loop_continue_here ();
|
||
incr = build_binary_op (PLUS_EXPR, idecl, integer_one_node, 0);
|
||
incr = build (MODIFY_EXPR, TREE_TYPE (idecl), idecl, incr);
|
||
TREE_SIDE_EFFECTS (incr) = 1;
|
||
expand_expr (incr, const0_rtx, VOIDmode, EXPAND_NORMAL);
|
||
test = build_binary_op (LT_EXPR, idecl, DECL_INITIAL (idecl), 0);
|
||
expand_exit_loop_if_false (0, test);
|
||
expand_end_loop ();
|
||
|
||
ITERATOR_BOUND_P (idecl) = 0;
|
||
/* we can reset rtl since there is not chance that this expansion */
|
||
/* would be superseded by a higher level one */
|
||
/* but don't do this if the decl is static, since we need to share */
|
||
/* the same decl in that case. */
|
||
if (top_level_ixpansion_p () && ! TREE_STATIC (idecl))
|
||
DECL_RTL (idecl) = 0;
|
||
if (end_note)
|
||
*end_note = emit_note (0, NOTE_INSN_DELETED);
|
||
}
|
||
|
||
/* Return true if we are not currently inside a "({...})" construct. */
|
||
|
||
static int
|
||
top_level_ixpansion_p ()
|
||
{
|
||
return iter_stack == 0;
|
||
}
|
||
|
||
/* Given two chains of iter_stack_nodes,
|
||
append the nodes in X into Y. */
|
||
|
||
static void
|
||
isn_append (x, y)
|
||
struct iter_stack_node *x, *y;
|
||
{
|
||
if (x->first == 0)
|
||
return;
|
||
|
||
if (y->first == 0)
|
||
{
|
||
y->first = x->first;
|
||
y->last = x->last;
|
||
}
|
||
else
|
||
{
|
||
y->last->next = x->first;
|
||
y->last = x->last;
|
||
}
|
||
}
|
||
|
||
/** Make X empty **/
|
||
|
||
#define ISN_ZERO(X) (X).first=(X).last=0
|
||
|
||
/* Move the ixpansions in sublevel_ixpansions into the current
|
||
node on the iter_stack, or discard them if the iter_stack is empty.
|
||
We do this at the end of a statement. */
|
||
|
||
static void
|
||
istack_sublevel_to_current ()
|
||
{
|
||
/* At the top level we can throw away sublevel's expansions **/
|
||
/* because there is nobody above us to ask for a cleanup **/
|
||
if (iter_stack != 0)
|
||
/** Merging with empty sublevel list is a no-op **/
|
||
if (sublevel_ixpansions.last)
|
||
isn_append (&sublevel_ixpansions, iter_stack);
|
||
|
||
if (iter_stack == 0)
|
||
obstack_free (&ixp_obstack, ixp_firstobj);
|
||
|
||
ISN_ZERO (sublevel_ixpansions);
|
||
}
|
||
|
||
/* Push a new node on the iter_stack, when we enter a ({...}). */
|
||
|
||
void
|
||
push_iterator_stack ()
|
||
{
|
||
struct iter_stack_node *new_top
|
||
= (struct iter_stack_node *)
|
||
obstack_alloc (&ixp_obstack, sizeof (struct iter_stack_node));
|
||
|
||
new_top->first = 0;
|
||
new_top->last = 0;
|
||
new_top->next = iter_stack;
|
||
iter_stack = new_top;
|
||
}
|
||
|
||
/* Pop iter_stack, moving the ixpansions in the node being popped
|
||
into sublevel_ixpansions. */
|
||
|
||
void
|
||
pop_iterator_stack ()
|
||
{
|
||
if (iter_stack == 0)
|
||
abort ();
|
||
|
||
isn_append (iter_stack, &sublevel_ixpansions);
|
||
/** Pop current level node: */
|
||
iter_stack = iter_stack->next;
|
||
}
|
||
|
||
|
||
/* Record an iterator expansion ("ixpansion") for IDECL.
|
||
The remaining parameters are the notes in the loop entry
|
||
and exit rtl. */
|
||
|
||
static void
|
||
add_ixpansion (idecl, pro_start, pro_end, epi_start, epi_end)
|
||
tree idecl;
|
||
rtx pro_start, pro_end, epi_start, epi_end;
|
||
{
|
||
struct ixpansion *newix;
|
||
|
||
/* Do nothing if we are not inside "({...})",
|
||
as in that case this expansion can't need subsequent RTL modification. */
|
||
if (iter_stack == 0)
|
||
return;
|
||
|
||
newix = (struct ixpansion *) obstack_alloc (&ixp_obstack,
|
||
sizeof (struct ixpansion));
|
||
newix->ixdecl = idecl;
|
||
newix->ixprologue_start = pro_start;
|
||
newix->ixprologue_end = pro_end;
|
||
newix->ixepilogue_start = epi_start;
|
||
newix->ixepilogue_end = epi_end;
|
||
|
||
newix->next = iter_stack->first;
|
||
iter_stack->first = newix;
|
||
if (iter_stack->last == 0)
|
||
iter_stack->last = newix;
|
||
}
|
||
|
||
/* Delete the RTL for all ixpansions for iterator IDECL
|
||
in our sublevels. We do this when we make a larger
|
||
containing expansion for IDECL. */
|
||
|
||
static void
|
||
delete_ixpansion (idecl)
|
||
tree idecl;
|
||
{
|
||
struct ixpansion *previx = 0, *ix;
|
||
|
||
for (ix = sublevel_ixpansions.first; ix; ix = ix->next)
|
||
if (ix->ixdecl == idecl)
|
||
{
|
||
/** zero means that this is a mark for FOR -- **/
|
||
/** we do not delete anything, just issue an error. **/
|
||
|
||
if (ix->ixprologue_start == 0)
|
||
error_with_decl (idecl,
|
||
"`for (%s)' appears within implicit iteration");
|
||
else
|
||
{
|
||
rtx insn;
|
||
/* We delete all insns, including notes because leaving loop */
|
||
/* notes and barriers produced by iterator expansion would */
|
||
/* be misleading to other phases */
|
||
|
||
for (insn = NEXT_INSN (ix->ixprologue_start);
|
||
insn != ix->ixprologue_end;
|
||
insn = NEXT_INSN (insn))
|
||
delete_insn (insn);
|
||
for (insn = NEXT_INSN (ix->ixepilogue_start);
|
||
insn != ix->ixepilogue_end;
|
||
insn = NEXT_INSN (insn))
|
||
delete_insn (insn);
|
||
}
|
||
|
||
/* Delete this ixpansion from sublevel_ixpansions. */
|
||
if (previx)
|
||
previx->next = ix->next;
|
||
else
|
||
sublevel_ixpansions.first = ix->next;
|
||
if (sublevel_ixpansions.last == ix)
|
||
sublevel_ixpansions.last = previx;
|
||
}
|
||
else
|
||
previx = ix;
|
||
}
|
||
|
||
#ifdef DEBUG_ITERATORS
|
||
|
||
/* The functions below are for use from source level debugger.
|
||
They print short forms of iterator lists and the iterator stack. */
|
||
|
||
/* Print the name of the iterator D. */
|
||
|
||
void
|
||
prdecl (d)
|
||
tree d;
|
||
{
|
||
if (d)
|
||
{
|
||
if (TREE_CODE (d) == VAR_DECL)
|
||
{
|
||
tree tname = DECL_NAME (d);
|
||
char *dname = IDENTIFIER_POINTER (tname);
|
||
fprintf (stderr, dname);
|
||
}
|
||
else
|
||
fprintf (stderr, "<<?>>");
|
||
}
|
||
else
|
||
fprintf (stderr, "<<0>>");
|
||
}
|
||
|
||
/* Print Iterator List -- names only */
|
||
|
||
tree
|
||
pil (head)
|
||
tree head;
|
||
{
|
||
tree current, next;
|
||
for (current = head; current; current = next)
|
||
{
|
||
tree node = TREE_VALUE (current);
|
||
prdecl (node);
|
||
next = TREE_CHAIN (current);
|
||
if (next) fprintf (stderr, ",");
|
||
}
|
||
fprintf (stderr, "\n");
|
||
}
|
||
|
||
/* Print IXpansion List */
|
||
|
||
struct ixpansion *
|
||
pixl (head)
|
||
struct ixpansion *head;
|
||
{
|
||
struct ixpansion *current, *next;
|
||
fprintf (stderr, "> ");
|
||
if (head == 0)
|
||
fprintf (stderr, "(empty)");
|
||
|
||
for (current=head; current; current = next)
|
||
{
|
||
tree node = current->ixdecl;
|
||
prdecl (node);
|
||
next = current->next;
|
||
if (next)
|
||
fprintf (stderr, ",");
|
||
}
|
||
fprintf (stderr, "\n");
|
||
return head;
|
||
}
|
||
|
||
/* Print Iterator Stack. */
|
||
|
||
void
|
||
pis ()
|
||
{
|
||
struct iter_stack_node *stack_node;
|
||
|
||
fprintf (stderr, "--SubLevel: ");
|
||
pixl (sublevel_ixpansions.first);
|
||
fprintf (stderr, "--Stack:--\n");
|
||
for (stack_node = iter_stack;
|
||
stack_node;
|
||
stack_node = stack_node->next)
|
||
pixl (stack_node->first);
|
||
}
|
||
|
||
#endif /* DEBUG_ITERATORS */
|