1 /* Perform optimizations on tree structure.
3 Copyright (C) 1998, 1999 Free Software Foundation, Inc.
4 Written by Mark Michell (mark@codesourcery.com).
6 This file is part of GNU CC.
8 GNU CC is free software; you can redistribute it and/or modify it
9 under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
13 GNU CC is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GNU CC; see the file COPYING. If not, write to the Free
20 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
28 #include "insn-config.h"
29 #include "integrate.h"
34 o In order to make inlining-on-trees work, we pessimized
35 function-local static constants. In particular, they are now
36 always output, even when not addressed. Fix this by treating
37 function-local static constants just like global static
38 constants; the back-end already knows not to output them if they
41 o Provide heuristics to clamp inlining of recursive template
44 o It looks like the return label is not being placed in the optimal
45 place. Shouldn't it come before the returned value? */
47 /* Data required for function inlining. */
49 typedef struct inline_data
51 /* A stack of the functions we are inlining. For example, if we are
52 compiling `f', which calls `g', which calls `h', and we are
53 inlining the body of `h', the stack will contain, `h', followed
54 by `g', followed by `f'. */
56 /* The last SCOPE_STMT we have encountered. */
58 /* The label to jump to when a return statement is encountered. */
60 /* The map from local declarations in the inlined function to
61 equivalents in the function into which it is being inlined. */
63 /* Nonzero if we are currently within the cleanup for a
65 int in_target_cleanup_p
;
70 static tree initialize_inlined_parameters
PROTO((inline_data
*, tree
));
71 static tree declare_return_variable
PROTO((inline_data
*, tree
*));
72 static tree copy_body_r
PROTO((tree
*, int *, void *));
73 static tree copy_body
PROTO((inline_data
*));
74 static tree expand_call_inline
PROTO((tree
*, int *, void *));
75 static void expand_calls_inline
PROTO((tree
*, inline_data
*));
76 static int inlinable_function_p
PROTO((tree
, inline_data
*));
77 static tree remap_decl
PROTO((tree
, inline_data
*));
78 static void remap_block
PROTO((tree
, tree
, inline_data
*));
79 static void copy_scope_stmt
PROTO((tree
*, int *, inline_data
*));
81 /* Remap DECL during the copying of the BLOCK tree for the function.
82 DATA is really an `inline_data *'. */
92 /* We only remap local variables in the current function. */
93 fn
= VARRAY_TOP_TREE (id
->fns
);
94 if (!nonstatic_local_decl_p (decl
) || DECL_CONTEXT (decl
) != fn
)
97 /* See if we have remapped this declaration. */
98 n
= splay_tree_lookup (id
->decl_map
, (splay_tree_key
) decl
);
99 /* If we didn't already have an equivalent for this declaration,
105 /* Make a copy of the variable or label. */
106 t
= copy_decl_for_inlining (decl
, fn
,
107 VARRAY_TREE (id
->fns
, 0));
108 /* Remember it, so that if we encounter this local entity
109 again we can reuse this copy. */
110 n
= splay_tree_insert (id
->decl_map
,
111 (splay_tree_key
) decl
,
112 (splay_tree_value
) t
);
115 return (tree
) n
->value
;
118 /* Copy the SCOPE_STMT_BLOCK associated with SCOPE_STMT to contain
119 remapped versions of the variables therein. And hook the new block
120 into the block-tree. If non-NULL, the DECLS are declarations to
121 add to use instead of the BLOCK_VARS in the old block. */
124 remap_block (scope_stmt
, decls
, id
)
129 /* We cannot do this in the cleanup for a TARGET_EXPR since we do
130 not know whether or not expand_expr will actually write out the
131 code we put there. If it does not, then we'll have more BLOCKs
132 than block-notes, and things will go awry. At some point, we
133 should make the back-end handle BLOCK notes in a tidier way,
134 without requiring a strict correspondence to the block-tree; then
135 this check can go. */
136 if (id
->in_target_cleanup_p
)
138 SCOPE_STMT_BLOCK (scope_stmt
) = NULL_TREE
;
142 /* If this is the beginning of a scope, remap the associated BLOCK. */
143 if (SCOPE_BEGIN_P (scope_stmt
) && SCOPE_STMT_BLOCK (scope_stmt
))
149 /* Make the new block. */
150 old_block
= SCOPE_STMT_BLOCK (scope_stmt
);
151 new_block
= make_node (BLOCK
);
152 TREE_USED (new_block
) = TREE_USED (old_block
);
153 BLOCK_ABSTRACT_ORIGIN (new_block
) = old_block
;
154 SCOPE_STMT_BLOCK (scope_stmt
) = new_block
;
156 /* Remap its variables. */
157 for (old_var
= decls
? decls
: BLOCK_VARS (old_block
);
159 old_var
= TREE_CHAIN (old_var
))
163 /* Remap the variable. */
164 new_var
= remap_decl (old_var
, id
);
166 /* We didn't remap this variable, so we can't mess with
171 TREE_CHAIN (new_var
) = BLOCK_VARS (new_block
);
172 BLOCK_VARS (new_block
) = new_var
;
175 /* We put the BLOCK_VARS in reverse order; fix that now. */
176 BLOCK_VARS (new_block
) = nreverse (BLOCK_VARS (new_block
));
177 /* Graft the new block into the tree. */
178 insert_block_after_note (new_block
,
180 ? SCOPE_STMT_BLOCK (id
->scope_stmt
)
183 ? SCOPE_BEGIN_P (id
->scope_stmt
) : 1),
184 VARRAY_TREE (id
->fns
, 0));
185 /* Remember that this is now the last scope statement with
186 an associated block. */
187 id
->scope_stmt
= scope_stmt
;
188 /* Remember the remapped block. */
189 splay_tree_insert (id
->decl_map
,
190 (splay_tree_key
) old_block
,
191 (splay_tree_value
) new_block
);
193 /* If this is the end of a scope, set the SCOPE_STMT_BLOCK to be the
195 else if (SCOPE_END_P (scope_stmt
) && SCOPE_STMT_BLOCK (scope_stmt
))
199 /* Find this block in the table of remapped things. */
200 n
= splay_tree_lookup (id
->decl_map
,
201 (splay_tree_key
) SCOPE_STMT_BLOCK (scope_stmt
));
202 my_friendly_assert (n
!= NULL
, 19991203);
203 SCOPE_STMT_BLOCK (scope_stmt
) = (tree
) n
->value
;
205 /* Remember that this is now the last scope statement with an
207 id
->scope_stmt
= scope_stmt
;
211 /* Copy the SCOPE_STMT pointed to by TP. */
214 copy_scope_stmt (tp
, walk_subtrees
, id
)
221 /* Remember whether or not this statement was nullified. When
222 making a copy, copy_tree_r always sets SCOPE_NULLIFIED_P (and
223 doesn't copy the SCOPE_STMT_BLOCK) to free callers from having to
224 deal with copying BLOCKs if they do not wish to do so. */
225 block
= SCOPE_STMT_BLOCK (*tp
);
226 /* Copy (and replace) the statement. */
227 copy_tree_r (tp
, walk_subtrees
, NULL
);
228 /* Restore the SCOPE_STMT_BLOCK. */
229 SCOPE_STMT_BLOCK (*tp
) = block
;
231 /* Remap the associated block. */
232 remap_block (*tp
, NULL_TREE
, id
);
235 /* Called from copy_body via walk_tree. DATA is really an
239 copy_body_r (tp
, walk_subtrees
, data
)
248 id
= (inline_data
*) data
;
249 fn
= VARRAY_TOP_TREE (id
->fns
);
251 /* All automatic variables should have a DECL_CONTEXT indicating
252 what function they come from. */
253 if ((TREE_CODE (*tp
) == VAR_DECL
|| TREE_CODE (*tp
) == LABEL_DECL
)
254 && DECL_NAMESPACE_SCOPE_P (*tp
))
255 my_friendly_assert (DECL_EXTERNAL (*tp
) || TREE_STATIC (*tp
),
258 /* If this is a RETURN_STMT, change it into an EXPR_STMT and a
259 GOTO_STMT with the RET_LABEL as its target. */
260 if (TREE_CODE (*tp
) == RETURN_STMT
)
262 tree return_stmt
= *tp
;
265 /* Build the GOTO_STMT. */
266 goto_stmt
= build_min_nt (GOTO_STMT
, id
->ret_label
);
267 TREE_CHAIN (goto_stmt
) = TREE_CHAIN (return_stmt
);
269 /* If we're returning something, just turn that into an
270 assignment into the equivalent of the original
272 if (RETURN_EXPR (return_stmt
))
274 *tp
= build_min_nt (EXPR_STMT
,
275 RETURN_EXPR (return_stmt
));
276 /* And then jump to the end of the function. */
277 TREE_CHAIN (*tp
) = goto_stmt
;
279 /* If we're not returning anything just do the jump. */
283 /* Local variables and labels need to be replaced by equivalent
284 variables. We don't want to copy static variables; there's only
285 one of those, no matter how many times we inline the containing
287 else if (nonstatic_local_decl_p (*tp
) && DECL_CONTEXT (*tp
) == fn
)
291 /* Remap the declaration. */
292 new_decl
= remap_decl (*tp
, id
);
293 my_friendly_assert (new_decl
!= NULL_TREE
, 19991203);
294 /* Replace this variable with the copy. */
297 else if (TREE_CODE (*tp
) == SAVE_EXPR
)
298 remap_save_expr (tp
, id
->decl_map
, VARRAY_TREE (id
->fns
, 0));
299 else if (TREE_CODE (*tp
) == UNSAVE_EXPR
)
300 my_friendly_abort (19991113);
301 /* For a SCOPE_STMT, we must copy the associated block so that we
302 can write out debugging information for the inlined variables. */
303 else if (TREE_CODE (*tp
) == SCOPE_STMT
&& !id
->in_target_cleanup_p
)
304 copy_scope_stmt (tp
, walk_subtrees
, id
);
305 /* Otherwise, just copy the node. Note that copy_tree_r already
306 knows not to copy VAR_DECLs, etc., so this is safe. */
309 copy_tree_r (tp
, walk_subtrees
, NULL
);
311 /* The copied TARGET_EXPR has never been expanded, even if the
312 original node was expanded already. */
313 if (TREE_CODE (*tp
) == TARGET_EXPR
&& TREE_OPERAND (*tp
, 3))
314 TREE_OPERAND (*tp
, 1) = TREE_OPERAND (*tp
, 3);
315 /* Similarly, if we're copying a CALL_EXPR, the RTL for the
316 result is no longer valid. */
317 else if (TREE_CODE (*tp
) == CALL_EXPR
)
318 CALL_EXPR_RTL (*tp
) = NULL_RTX
;
321 /* Keep iterating. */
325 /* Make a copy of the body of FN so that it can be inserted inline in
334 body
= DECL_SAVED_TREE (VARRAY_TOP_TREE (id
->fns
));
335 walk_tree (&body
, copy_body_r
, id
);
340 /* Generate code to initialize the parameters of the function at the
341 top of the stack in ID from the ARGS (presented as a TREE_LIST). */
344 initialize_inlined_parameters (id
, args
)
354 /* Figure out what the parameters are. */
355 fn
= VARRAY_TOP_TREE (id
->fns
);
356 parms
= DECL_ARGUMENTS (fn
);
358 /* Start with no initializations whatsoever. */
359 init_stmts
= NULL_TREE
;
361 /* Loop through the parameter declarations, replacing each with an
362 equivalent VAR_DECL, appropriately initialized. */
363 for (p
= parms
, a
= args
; p
; a
= TREE_CHAIN (a
), p
= TREE_CHAIN (p
))
368 /* Make an equivalent VAR_DECL. */
369 var
= copy_decl_for_inlining (p
, fn
, VARRAY_TREE (id
->fns
, 0));
370 /* Register the VAR_DECL as the equivalent for the PARM_DECL;
371 that way, when the PARM_DECL is encountered, it will be
372 automatically replaced by the VAR_DECL. */
373 splay_tree_insert (id
->decl_map
,
375 (splay_tree_value
) var
);
376 /* Initialize this VAR_DECL from the equivalent argument. If
377 the argument is an object, created via a constructor or copy,
378 this will not result in an extra copy: the TARGET_EXPR
379 representing the argument will be bound to VAR, and the
380 object will be constructed in VAR. */
381 init_stmt
= build_min_nt (EXPR_STMT
,
382 build (INIT_EXPR
, TREE_TYPE (p
),
383 var
, TREE_VALUE (a
)));
384 /* Declare this new variable. Note that we do this *after* the
385 initialization because we are going to reverse all the
386 initialization statements below. */
387 TREE_CHAIN (init_stmt
) = build_min_nt (DECL_STMT
, var
);
388 /* Add this initialization to the list. */
389 TREE_CHAIN (TREE_CHAIN (init_stmt
)) = init_stmts
;
390 init_stmts
= init_stmt
;
393 /* The initialization statements have been built up in reverse
394 order. Straighten them out now. */
395 return nreverse (init_stmts
);
398 /* Declare a return variable to replace the RESULT_DECL for the
399 function we are calling. An appropriate DECL_STMT is returned.
400 The USE_STMT is filled in to contain a use of the declaration to
401 indicate the return value of the function. */
404 declare_return_variable (id
, use_stmt
)
405 struct inline_data
*id
;
408 tree fn
= VARRAY_TOP_TREE (id
->fns
);
409 tree result
= DECL_RESULT (fn
);
412 /* We don't need to do anything for functions that don't return
414 if (!result
|| same_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (result
)),
417 *use_stmt
= NULL_TREE
;
421 /* Make an appropriate copy. */
422 var
= copy_decl_for_inlining (result
, fn
, VARRAY_TREE (id
->fns
, 0));
423 /* Register the VAR_DECL as the equivalent for the RESULT_DECL; that
424 way, when the RESULT_DECL is encountered, it will be
425 automatically replaced by the VAR_DECL. */
426 splay_tree_insert (id
->decl_map
,
427 (splay_tree_key
) result
,
428 (splay_tree_value
) var
);
430 /* Build the USE_STMT. */
431 *use_stmt
= build_min_nt (EXPR_STMT
, var
);
433 /* Build the declaration statement. */
434 return build_min_nt (DECL_STMT
, var
);
437 /* Returns non-zero if FN is a function that can be inlined. */
440 inlinable_function_p (fn
, id
)
446 /* If we've already decided this function shouldn't be inlined,
447 there's no need to check again. */
448 if (DECL_UNINLINABLE (fn
))
451 /* Assume it is not inlinable. */
454 /* If we're not inlining things, then nothing is inlinable. */
455 if (!flag_inline_trees
)
457 /* If the function was not declared `inline', then we don't inline
459 else if (!DECL_INLINE (fn
))
461 /* If we don't have the function body available, we can't inline
463 else if (!DECL_SAVED_TREE (fn
))
465 /* We can't inline varargs functions. */
466 else if (varargs_function_p (fn
))
468 /* All is well. We can inline this function. Traditionally, GCC
469 has refused to inline functions using setjmp or alloca, or
470 functions whose values are returned in a PARALLEL, and a few
471 other such obscure conditions. We are not equally constrained at
476 /* Squirrel away the result so that we don't have to check again. */
477 DECL_UNINLINABLE (fn
) = !inlinable
;
479 /* Don't do recursive inlining, either. We don't record this in
480 DECL_UNLINABLE; we may be able to inline this function later. */
485 for (i
= 0; i
< id
->fns
->elements_used
; ++i
)
486 if (VARRAY_TREE (id
->fns
, i
) == fn
)
490 /* We can inline a template instantiation only if its fully
493 && DECL_TEMPLATE_INFO (fn
)
494 && TI_PENDING_TEMPLATE_FLAG (DECL_TEMPLATE_INFO (fn
)))
496 fn
= instantiate_decl (fn
);
497 inlinable
= !TI_PENDING_TEMPLATE_FLAG (DECL_TEMPLATE_INFO (fn
));
500 /* Return the result. */
504 /* If *TP is CALL_EXPR, replace it with its inline expansion. */
507 expand_call_inline (tp
, walk_subtrees
, data
)
521 /* See what we've got. */
522 id
= (inline_data
*) data
;
525 /* Keep track of the last SCOPE_STMT we've seen. */
526 if (TREE_CODE (t
) == SCOPE_STMT
)
528 if (SCOPE_STMT_BLOCK (t
) && !id
->in_target_cleanup_p
)
533 /* Recurse, but letting recursive invocations know that we are
534 inside the body of a TARGET_EXPR. */
535 if (TREE_CODE (*tp
) == TARGET_EXPR
)
539 /* We're walking our own subtrees. */
542 /* Actually walk over them. This loop is the body of
543 walk_trees, omitting the case where the TARGET_EXPR
544 itself is handled. */
545 for (i
= first_rtl_op (TARGET_EXPR
) - 1; i
>= 0; --i
)
548 ++id
->in_target_cleanup_p
;
549 walk_tree (&TREE_OPERAND (*tp
, i
), expand_call_inline
, data
);
551 --id
->in_target_cleanup_p
;
557 /* From here on, we're only interested in CALL_EXPRs. */
558 if (TREE_CODE (t
) != CALL_EXPR
)
561 /* First, see if we can figure out what function is being called.
562 If we cannot, then there is no hope of inlining the function. */
563 fn
= get_callee_fndecl (t
);
567 /* Don't try to inline functions that are not well-suited to
569 if (!inlinable_function_p (fn
, id
))
572 /* Return statements in the function body will be replaced by jumps
574 id
->ret_label
= build_decl (LABEL_DECL
, NULL_TREE
, NULL_TREE
);
575 DECL_CONTEXT (id
->ret_label
) = VARRAY_TREE (id
->fns
, 0);
577 /* Build a statement-expression containing code to initialize the
578 arguments, the actual inline expansion of the body, and a label
579 for the return statements within the function to jump to. The
580 type of the statement expression is the return type of the
582 expr
= build_min (STMT_EXPR
, TREE_TYPE (TREE_TYPE (fn
)), NULL_TREE
);
584 /* Record the function we are about to inline so that we can avoid
585 recursing into it. */
586 VARRAY_PUSH_TREE (id
->fns
, fn
);
588 /* Local declarations will be replaced by their equivalents in this
591 id
->decl_map
= splay_tree_new (splay_tree_compare_pointers
,
594 /* Initialize the parameters. */
595 STMT_EXPR_STMT (expr
)
596 = initialize_inlined_parameters (id
, TREE_OPERAND (t
, 1));
598 /* Create a block to put the parameters in. We have to do this
599 after the parameters have been remapped because remapping
600 parameters is different from remapping ordinary variables. */
601 scope_stmt
= build_min_nt (SCOPE_STMT
, DECL_INITIAL (fn
));
602 SCOPE_BEGIN_P (scope_stmt
) = 1;
603 SCOPE_NO_CLEANUPS_P (scope_stmt
) = 1;
604 remap_block (scope_stmt
, DECL_ARGUMENTS (fn
), id
);
605 TREE_CHAIN (scope_stmt
) = STMT_EXPR_STMT (expr
);
606 STMT_EXPR_STMT (expr
) = scope_stmt
;
607 id
->scope_stmt
= scope_stmt
;
609 /* Declare the return variable for the function. */
610 STMT_EXPR_STMT (expr
)
611 = chainon (STMT_EXPR_STMT (expr
),
612 declare_return_variable (id
, &use_stmt
));
614 /* After we've initialized the parameters, we insert the body of the
616 STMT_EXPR_STMT (expr
)
617 = chainon (STMT_EXPR_STMT (expr
), copy_body (id
));
619 /* Close the block for the parameters. */
620 scope_stmt
= build_min_nt (SCOPE_STMT
, DECL_INITIAL (fn
));
621 SCOPE_NO_CLEANUPS_P (scope_stmt
) = 1;
622 my_friendly_assert (DECL_INITIAL (fn
)
623 && TREE_CODE (DECL_INITIAL (fn
)) == BLOCK
,
625 remap_block (scope_stmt
, NULL_TREE
, id
);
626 STMT_EXPR_STMT (expr
)
627 = chainon (STMT_EXPR_STMT (expr
), scope_stmt
);
629 /* Finally, mention the returned value so that the value of the
630 statement-expression is the returned value of the function. */
631 STMT_EXPR_STMT (expr
) = chainon (STMT_EXPR_STMT (expr
), use_stmt
);
634 splay_tree_delete (id
->decl_map
);
637 /* After the body of the function comes the RET_LABEL. */
638 STMT_EXPR_STMT (expr
)
639 = chainon (STMT_EXPR_STMT (expr
),
640 build_min_nt (LABEL_STMT
, id
->ret_label
));
642 /* The new expression has side-effects if the old one did. */
643 TREE_SIDE_EFFECTS (expr
) = TREE_SIDE_EFFECTS (t
);
644 /* If the value of the new expression is ignored, that's OK. We
645 don't warn about this for CALL_EXPRs, so we shouldn't warn about
646 the equivalent inlined version either. */
647 TREE_USED (expr
) = 1;
649 /* Replace the call by the inlined body. */
650 chain
= TREE_CHAIN (*tp
);
652 TREE_CHAIN (expr
) = chain
;
654 /* Recurse into the body of the just inlined function. */
655 expand_calls_inline (tp
, id
);
656 VARRAY_POP (id
->fns
);
658 /* Don't walk into subtrees. We've already handled them above. */
661 /* Keep iterating. */
665 /* Walk over the entire tree *TP, replacing CALL_EXPRs with inline
666 expansions as appropriate. */
669 expand_calls_inline (tp
, id
)
673 /* Search through *TP, replacing all calls to inline functions by
674 appropriate equivalents. */
675 walk_tree (tp
, expand_call_inline
, id
);
678 /* Optimize the body of FN. */
681 optimize_function (fn
)
684 /* Expand calls to inline functions. */
685 if (flag_inline_trees
)
689 struct saved_scope
*s
;
692 bzero (&id
, sizeof (id
));
694 /* Don't allow recursion into FN. */
695 VARRAY_TREE_INIT (id
.fns
, 32, "fns");
696 VARRAY_PUSH_TREE (id
.fns
, fn
);
697 /* Or any functions that aren't finished yet. */
699 if (current_function_decl
)
701 VARRAY_PUSH_TREE (id
.fns
, current_function_decl
);
702 prev_fn
= current_function_decl
;
704 for (s
= scope_chain
; s
; s
= s
->prev
)
705 if (s
->function_decl
&& s
->function_decl
!= prev_fn
)
707 VARRAY_PUSH_TREE (id
.fns
, s
->function_decl
);
708 prev_fn
= s
->function_decl
;
710 /* Replace all calls to inline functions with the bodies of those
712 expand_calls_inline (&DECL_SAVED_TREE (fn
), &id
);
715 VARRAY_FREE (id
.fns
);