1 /* Control flow optimization code for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
22 /* This file contains helper functions for Cross jumping (tail merging). */
26 #include "coretypes.h"
31 #include "insn-config.h"
38 static void merge_memattrs (rtx, rtx);
42 /* Removes the memory attributes of MEM expression
43 if they are not equal. */
46 merge_memattrs (rtx x, rtx y)
60 if (code != GET_CODE (y))
63 if (GET_MODE (x) != GET_MODE (y))
66 if (code == MEM && MEM_ATTRS (x) != MEM_ATTRS (y))
70 else if (! MEM_ATTRS (y))
76 if (MEM_ALIAS_SET (x) != MEM_ALIAS_SET (y))
78 set_mem_alias_set (x, 0);
79 set_mem_alias_set (y, 0);
82 if (! mem_expr_equal_p (MEM_EXPR (x), MEM_EXPR (y)))
86 set_mem_offset (x, 0);
87 set_mem_offset (y, 0);
89 else if (MEM_OFFSET (x) != MEM_OFFSET (y))
91 set_mem_offset (x, 0);
92 set_mem_offset (y, 0);
97 else if (!MEM_SIZE (y))
100 mem_size = GEN_INT (MAX (INTVAL (MEM_SIZE (x)),
101 INTVAL (MEM_SIZE (y))));
102 set_mem_size (x, mem_size);
103 set_mem_size (y, mem_size);
105 set_mem_align (x, MIN (MEM_ALIGN (x), MEM_ALIGN (y)));
106 set_mem_align (y, MEM_ALIGN (x));
110 fmt = GET_RTX_FORMAT (code);
111 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
116 /* Two vectors must have the same length. */
117 if (XVECLEN (x, i) != XVECLEN (y, i))
120 for (j = 0; j < XVECLEN (x, i); j++)
121 merge_memattrs (XVECEXP (x, i, j), XVECEXP (y, i, j));
126 merge_memattrs (XEXP (x, i), XEXP (y, i));
132 /* Check if the set of REG_DEAD notes attached to I1 and I2 allows us to
133 go ahead with merging I1 and I2, which otherwise look fine. */
135 death_notes_match_p (rtx i1 ATTRIBUTE_UNUSED, rtx i2 ATTRIBUTE_UNUSED,
136 int mode ATTRIBUTE_UNUSED)
139 /* If cross_jump_death_matters is not 0, the insn's mode
140 indicates whether or not the insn contains any stack-like
143 if ((mode & CLEANUP_POST_REGSTACK) && stack_regs_mentioned (i1))
145 /* If register stack conversion has already been done, then
146 death notes must also be compared before it is certain that
147 the two instruction streams match. */
150 HARD_REG_SET i1_regset, i2_regset;
152 CLEAR_HARD_REG_SET (i1_regset);
153 CLEAR_HARD_REG_SET (i2_regset);
155 for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
156 if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0)))
157 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
159 for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
160 if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0)))
161 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
163 GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done);
174 /* Return true if I1 and I2 are equivalent and thus can be crossjumped. */
177 insns_match_p (int mode, rtx i1, rtx i2)
181 /* Verify that I1 and I2 are equivalent. */
182 if (GET_CODE (i1) != GET_CODE (i2))
188 if (GET_CODE (p1) != GET_CODE (p2))
191 /* If this is a CALL_INSN, compare register usage information.
192 If we don't check this on stack register machines, the two
193 CALL_INSNs might be merged leaving reg-stack.c with mismatching
194 numbers of stack registers in the same basic block.
195 If we don't check this on machines with delay slots, a delay slot may
196 be filled that clobbers a parameter expected by the subroutine.
198 ??? We take the simple route for now and assume that if they're
199 equal, they were constructed identically. */
202 && (!rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
203 CALL_INSN_FUNCTION_USAGE (i2))
204 || SIBLING_CALL_P (i1) != SIBLING_CALL_P (i2)))
207 if (!death_notes_match_p (i1, i2, mode))
211 ? rtx_renumbered_equal_p (p1, p2) : rtx_equal_p (p1, p2))
214 /* Do not do EQUIV substitution after reload. First, we're undoing the
215 work of reload_cse. Second, we may be undoing the work of the post-
216 reload splitting pass. */
217 /* ??? Possibly add a new phase switch variable that can be used by
218 targets to disallow the troublesome insns after splitting. */
219 if (!reload_completed)
221 /* The following code helps take care of G++ cleanups. */
222 rtx equiv1 = find_reg_equal_equiv_note (i1);
223 rtx equiv2 = find_reg_equal_equiv_note (i2);
226 /* If the equivalences are not to a constant, they may
227 reference pseudos that no longer exist, so we can't
229 && (! reload_completed
230 || (CONSTANT_P (XEXP (equiv1, 0))
231 && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))))
233 rtx s1 = single_set (i1);
234 rtx s2 = single_set (i2);
235 if (s1 != 0 && s2 != 0
236 && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2)))
238 validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1);
239 validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1);
240 if (! rtx_renumbered_equal_p (p1, p2))
242 else if (apply_change_group ())
251 /* Look through the insns at the end of BB1 and BB2 and find the longest
252 sequence that are equivalent. Store the first insns for that sequence
253 in *F1 and *F2 and return the sequence length.
255 To simplify callers of this function, if the blocks match exactly,
256 store the head of the blocks in *F1 and *F2. */
259 flow_find_cross_jump (int mode ATTRIBUTE_UNUSED, basic_block bb1,
260 basic_block bb2, rtx *f1, rtx *f2)
262 rtx i1, i2, last1, last2, afterlast1, afterlast2;
265 /* Skip simple jumps at the end of the blocks. Complex jumps still
266 need to be compared for equivalence, which we'll do below. */
269 last1 = afterlast1 = last2 = afterlast2 = NULL_RTX;
271 || (returnjump_p (i1) && !side_effects_p (PATTERN (i1))))
279 || (returnjump_p (i2) && !side_effects_p (PATTERN (i2))))
282 /* Count everything except for unconditional jump as insn. */
283 if (!simplejump_p (i2) && !returnjump_p (i2) && last1)
291 while (!INSN_P (i1) && i1 != BB_HEAD (bb1))
294 while (!INSN_P (i2) && i2 != BB_HEAD (bb2))
297 if (i1 == BB_HEAD (bb1) || i2 == BB_HEAD (bb2))
300 if (!insns_match_p (mode, i1, i2))
303 merge_memattrs (i1, i2);
305 /* Don't begin a cross-jump with a NOTE insn. */
308 /* If the merged insns have different REG_EQUAL notes, then
310 rtx equiv1 = find_reg_equal_equiv_note (i1);
311 rtx equiv2 = find_reg_equal_equiv_note (i2);
313 if (equiv1 && !equiv2)
314 remove_note (i1, equiv1);
315 else if (!equiv1 && equiv2)
316 remove_note (i2, equiv2);
317 else if (equiv1 && equiv2
318 && !rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
320 remove_note (i1, equiv1);
321 remove_note (i2, equiv2);
324 afterlast1 = last1, afterlast2 = last2;
325 last1 = i1, last2 = i2;
334 /* Don't allow the insn after a compare to be shared by
335 cross-jumping unless the compare is also shared. */
336 if (ninsns && reg_mentioned_p (cc0_rtx, last1) && ! sets_cc0_p (last1))
337 last1 = afterlast1, last2 = afterlast2, ninsns--;
340 /* Include preceding notes and labels in the cross-jump. One,
341 this may bring us to the head of the blocks as requested above.
342 Two, it keeps line number notes as matched as may be. */
345 while (last1 != BB_HEAD (bb1) && !INSN_P (PREV_INSN (last1)))
346 last1 = PREV_INSN (last1);
348 if (last1 != BB_HEAD (bb1) && LABEL_P (PREV_INSN (last1)))
349 last1 = PREV_INSN (last1);
351 while (last2 != BB_HEAD (bb2) && !INSN_P (PREV_INSN (last2)))
352 last2 = PREV_INSN (last2);
354 if (last2 != BB_HEAD (bb2) && LABEL_P (PREV_INSN (last2)))
355 last2 = PREV_INSN (last2);