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[/] [openrisc/] [trunk/] [gnu-src/] [gcc-4.5.1/] [gcc/] [cfgrtl.c] - Rev 280
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/* Control flow graph manipulation code for GNU compiler. Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc. This file is part of GCC. GCC 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 3, or (at your option) any later version. GCC 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 GCC; see the file COPYING3. If not see <http://www.gnu.org/licenses/>. */ /* This file contains low level functions to manipulate the CFG and analyze it that are aware of the RTL intermediate language. Available functionality: - Basic CFG/RTL manipulation API documented in cfghooks.h - CFG-aware instruction chain manipulation delete_insn, delete_insn_chain - Edge splitting and committing to edges insert_insn_on_edge, commit_edge_insertions - CFG updating after insn simplification purge_dead_edges, purge_all_dead_edges Functions not supposed for generic use: - Infrastructure to determine quickly basic block for insn compute_bb_for_insn, update_bb_for_insn, set_block_for_insn, - Edge redirection with updating and optimizing of insn chain block_label, tidy_fallthru_edge, force_nonfallthru */ #include "config.h" #include "system.h" #include "coretypes.h" #include "tm.h" #include "tree.h" #include "rtl.h" #include "hard-reg-set.h" #include "basic-block.h" #include "regs.h" #include "flags.h" #include "output.h" #include "function.h" #include "except.h" #include "toplev.h" #include "tm_p.h" #include "obstack.h" #include "insn-attr.h" #include "insn-config.h" #include "cfglayout.h" #include "expr.h" #include "target.h" #include "cfgloop.h" #include "ggc.h" #include "tree-pass.h" #include "df.h" static int can_delete_note_p (const_rtx); static int can_delete_label_p (const_rtx); static basic_block rtl_split_edge (edge); static bool rtl_move_block_after (basic_block, basic_block); static int rtl_verify_flow_info (void); static basic_block cfg_layout_split_block (basic_block, void *); static edge cfg_layout_redirect_edge_and_branch (edge, basic_block); static basic_block cfg_layout_redirect_edge_and_branch_force (edge, basic_block); static void cfg_layout_delete_block (basic_block); static void rtl_delete_block (basic_block); static basic_block rtl_redirect_edge_and_branch_force (edge, basic_block); static edge rtl_redirect_edge_and_branch (edge, basic_block); static basic_block rtl_split_block (basic_block, void *); static void rtl_dump_bb (basic_block, FILE *, int, int); static int rtl_verify_flow_info_1 (void); static void rtl_make_forwarder_block (edge); /* Return true if NOTE is not one of the ones that must be kept paired, so that we may simply delete it. */ static int can_delete_note_p (const_rtx note) { switch (NOTE_KIND (note)) { case NOTE_INSN_DELETED: case NOTE_INSN_BASIC_BLOCK: case NOTE_INSN_EPILOGUE_BEG: return true; default: return false; } } /* True if a given label can be deleted. */ static int can_delete_label_p (const_rtx label) { return (!LABEL_PRESERVE_P (label) /* User declared labels must be preserved. */ && LABEL_NAME (label) == 0 && !in_expr_list_p (forced_labels, label)); } /* Delete INSN by patching it out. Return the next insn. */ rtx delete_insn (rtx insn) { rtx next = NEXT_INSN (insn); rtx note; bool really_delete = true; if (LABEL_P (insn)) { /* Some labels can't be directly removed from the INSN chain, as they might be references via variables, constant pool etc. Convert them to the special NOTE_INSN_DELETED_LABEL note. */ if (! can_delete_label_p (insn)) { const char *name = LABEL_NAME (insn); really_delete = false; PUT_CODE (insn, NOTE); NOTE_KIND (insn) = NOTE_INSN_DELETED_LABEL; NOTE_DELETED_LABEL_NAME (insn) = name; } remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels); } if (really_delete) { /* If this insn has already been deleted, something is very wrong. */ gcc_assert (!INSN_DELETED_P (insn)); remove_insn (insn); INSN_DELETED_P (insn) = 1; } /* If deleting a jump, decrement the use count of the label. Deleting the label itself should happen in the normal course of block merging. */ if (JUMP_P (insn)) { if (JUMP_LABEL (insn) && LABEL_P (JUMP_LABEL (insn))) LABEL_NUSES (JUMP_LABEL (insn))--; /* If there are more targets, remove them too. */ while ((note = find_reg_note (insn, REG_LABEL_TARGET, NULL_RTX)) != NULL_RTX && LABEL_P (XEXP (note, 0))) { LABEL_NUSES (XEXP (note, 0))--; remove_note (insn, note); } } /* Also if deleting any insn that references a label as an operand. */ while ((note = find_reg_note (insn, REG_LABEL_OPERAND, NULL_RTX)) != NULL_RTX && LABEL_P (XEXP (note, 0))) { LABEL_NUSES (XEXP (note, 0))--; remove_note (insn, note); } if (JUMP_TABLE_DATA_P (insn)) { rtx pat = PATTERN (insn); int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC; int len = XVECLEN (pat, diff_vec_p); int i; for (i = 0; i < len; i++) { rtx label = XEXP (XVECEXP (pat, diff_vec_p, i), 0); /* When deleting code in bulk (e.g. removing many unreachable blocks) we can delete a label that's a target of the vector before deleting the vector itself. */ if (!NOTE_P (label)) LABEL_NUSES (label)--; } } return next; } /* Like delete_insn but also purge dead edges from BB. */ rtx delete_insn_and_edges (rtx insn) { rtx x; bool purge = false; if (INSN_P (insn) && BLOCK_FOR_INSN (insn) && BB_END (BLOCK_FOR_INSN (insn)) == insn) purge = true; x = delete_insn (insn); if (purge) purge_dead_edges (BLOCK_FOR_INSN (insn)); return x; } /* Unlink a chain of insns between START and FINISH, leaving notes that must be paired. If CLEAR_BB is true, we set bb field for insns that cannot be removed to NULL. */ void delete_insn_chain (rtx start, rtx finish, bool clear_bb) { rtx next; /* Unchain the insns one by one. It would be quicker to delete all of these with a single unchaining, rather than one at a time, but we need to keep the NOTE's. */ while (1) { next = NEXT_INSN (start); if (NOTE_P (start) && !can_delete_note_p (start)) ; else next = delete_insn (start); if (clear_bb && !INSN_DELETED_P (start)) set_block_for_insn (start, NULL); if (start == finish) break; start = next; } } /* Create a new basic block consisting of the instructions between HEAD and END inclusive. This function is designed to allow fast BB construction - reuses the note and basic block struct in BB_NOTE, if any and do not grow BASIC_BLOCK chain and should be used directly only by CFG construction code. END can be NULL in to create new empty basic block before HEAD. Both END and HEAD can be NULL to create basic block at the end of INSN chain. AFTER is the basic block we should be put after. */ basic_block create_basic_block_structure (rtx head, rtx end, rtx bb_note, basic_block after) { basic_block bb; if (bb_note && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL && bb->aux == NULL) { /* If we found an existing note, thread it back onto the chain. */ rtx after; if (LABEL_P (head)) after = head; else { after = PREV_INSN (head); head = bb_note; } if (after != bb_note && NEXT_INSN (after) != bb_note) reorder_insns_nobb (bb_note, bb_note, after); } else { /* Otherwise we must create a note and a basic block structure. */ bb = alloc_block (); init_rtl_bb_info (bb); if (!head && !end) head = end = bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ()); else if (LABEL_P (head) && end) { bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head); if (head == end) end = bb_note; } else { bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head); head = bb_note; if (!end) end = head; } NOTE_BASIC_BLOCK (bb_note) = bb; } /* Always include the bb note in the block. */ if (NEXT_INSN (end) == bb_note) end = bb_note; BB_HEAD (bb) = head; BB_END (bb) = end; bb->index = last_basic_block++; bb->flags = BB_NEW | BB_RTL; link_block (bb, after); SET_BASIC_BLOCK (bb->index, bb); df_bb_refs_record (bb->index, false); update_bb_for_insn (bb); BB_SET_PARTITION (bb, BB_UNPARTITIONED); /* Tag the block so that we know it has been used when considering other basic block notes. */ bb->aux = bb; return bb; } /* Create new basic block consisting of instructions in between HEAD and END and place it to the BB chain after block AFTER. END can be NULL in to create new empty basic block before HEAD. Both END and HEAD can be NULL to create basic block at the end of INSN chain. */ static basic_block rtl_create_basic_block (void *headp, void *endp, basic_block after) { rtx head = (rtx) headp, end = (rtx) endp; basic_block bb; /* Grow the basic block array if needed. */ if ((size_t) last_basic_block >= VEC_length (basic_block, basic_block_info)) { size_t new_size = last_basic_block + (last_basic_block + 3) / 4; VEC_safe_grow_cleared (basic_block, gc, basic_block_info, new_size); } n_basic_blocks++; bb = create_basic_block_structure (head, end, NULL, after); bb->aux = NULL; return bb; } static basic_block cfg_layout_create_basic_block (void *head, void *end, basic_block after) { basic_block newbb = rtl_create_basic_block (head, end, after); return newbb; } /* Delete the insns in a (non-live) block. We physically delete every non-deleted-note insn, and update the flow graph appropriately. Return nonzero if we deleted an exception handler. */ /* ??? Preserving all such notes strikes me as wrong. It would be nice to post-process the stream to remove empty blocks, loops, ranges, etc. */ static void rtl_delete_block (basic_block b) { rtx insn, end; /* If the head of this block is a CODE_LABEL, then it might be the label for an exception handler which can't be reached. We need to remove the label from the exception_handler_label list. */ insn = BB_HEAD (b); end = get_last_bb_insn (b); /* Selectively delete the entire chain. */ BB_HEAD (b) = NULL; delete_insn_chain (insn, end, true); if (dump_file) fprintf (dump_file, "deleting block %d\n", b->index); df_bb_delete (b->index); } /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */ void compute_bb_for_insn (void) { basic_block bb; FOR_EACH_BB (bb) { rtx end = BB_END (bb); rtx insn; for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn)) { BLOCK_FOR_INSN (insn) = bb; if (insn == end) break; } } } /* Release the basic_block_for_insn array. */ unsigned int free_bb_for_insn (void) { rtx insn; for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) if (!BARRIER_P (insn)) BLOCK_FOR_INSN (insn) = NULL; return 0; } static unsigned int rest_of_pass_free_cfg (void) { #ifdef DELAY_SLOTS /* The resource.c machinery uses DF but the CFG isn't guaranteed to be valid at that point so it would be too late to call df_analyze. */ if (optimize > 0 && flag_delayed_branch) df_analyze (); #endif free_bb_for_insn (); return 0; } struct rtl_opt_pass pass_free_cfg = { { RTL_PASS, "*free_cfg", /* name */ NULL, /* gate */ rest_of_pass_free_cfg, /* execute */ NULL, /* sub */ NULL, /* next */ 0, /* static_pass_number */ TV_NONE, /* tv_id */ 0, /* properties_required */ 0, /* properties_provided */ PROP_cfg, /* properties_destroyed */ 0, /* todo_flags_start */ 0, /* todo_flags_finish */ } }; /* Return RTX to emit after when we want to emit code on the entry of function. */ rtx entry_of_function (void) { return (n_basic_blocks > NUM_FIXED_BLOCKS ? BB_HEAD (ENTRY_BLOCK_PTR->next_bb) : get_insns ()); } /* Emit INSN at the entry point of the function, ensuring that it is only executed once per function. */ void emit_insn_at_entry (rtx insn) { edge_iterator ei = ei_start (ENTRY_BLOCK_PTR->succs); edge e = ei_safe_edge (ei); gcc_assert (e->flags & EDGE_FALLTHRU); insert_insn_on_edge (insn, e); commit_edge_insertions (); } /* Update BLOCK_FOR_INSN of insns between BEGIN and END (or BARRIER if found) and notify df of the bb change. The insn chain range is inclusive (i.e. both BEGIN and END will be updated. */ static void update_bb_for_insn_chain (rtx begin, rtx end, basic_block bb) { rtx insn; end = NEXT_INSN (end); for (insn = begin; insn != end; insn = NEXT_INSN (insn)) if (!BARRIER_P (insn)) df_insn_change_bb (insn, bb); } /* Update BLOCK_FOR_INSN of insns in BB to BB, and notify df of the change. */ void update_bb_for_insn (basic_block bb) { update_bb_for_insn_chain (BB_HEAD (bb), BB_END (bb), bb); } /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK note associated with the BLOCK. */ static rtx first_insn_after_basic_block_note (basic_block block) { rtx insn; /* Get the first instruction in the block. */ insn = BB_HEAD (block); if (insn == NULL_RTX) return NULL_RTX; if (LABEL_P (insn)) insn = NEXT_INSN (insn); gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn)); return NEXT_INSN (insn); } /* Creates a new basic block just after basic block B by splitting everything after specified instruction I. */ static basic_block rtl_split_block (basic_block bb, void *insnp) { basic_block new_bb; rtx insn = (rtx) insnp; edge e; edge_iterator ei; if (!insn) { insn = first_insn_after_basic_block_note (bb); if (insn) { rtx next = insn; insn = PREV_INSN (insn); /* If the block contains only debug insns, insn would have been NULL in a non-debug compilation, and then we'd end up emitting a DELETED note. For -fcompare-debug stability, emit the note too. */ if (insn != BB_END (bb) && DEBUG_INSN_P (next) && DEBUG_INSN_P (BB_END (bb))) { while (next != BB_END (bb) && DEBUG_INSN_P (next)) next = NEXT_INSN (next); if (next == BB_END (bb)) emit_note_after (NOTE_INSN_DELETED, next); } } else insn = get_last_insn (); } /* We probably should check type of the insn so that we do not create inconsistent cfg. It is checked in verify_flow_info anyway, so do not bother. */ if (insn == BB_END (bb)) emit_note_after (NOTE_INSN_DELETED, insn); /* Create the new basic block. */ new_bb = create_basic_block (NEXT_INSN (insn), BB_END (bb), bb); BB_COPY_PARTITION (new_bb, bb); BB_END (bb) = insn; /* Redirect the outgoing edges. */ new_bb->succs = bb->succs; bb->succs = NULL; FOR_EACH_EDGE (e, ei, new_bb->succs) e->src = new_bb; /* The new block starts off being dirty. */ df_set_bb_dirty (bb); return new_bb; } /* Blocks A and B are to be merged into a single block A. The insns are already contiguous. */ static void rtl_merge_blocks (basic_block a, basic_block b) { rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a); rtx del_first = NULL_RTX, del_last = NULL_RTX; rtx b_debug_start = b_end, b_debug_end = b_end; int b_empty = 0; if (dump_file) fprintf (dump_file, "merging block %d into block %d\n", b->index, a->index); while (DEBUG_INSN_P (b_end)) b_end = PREV_INSN (b_debug_start = b_end); /* If there was a CODE_LABEL beginning B, delete it. */ if (LABEL_P (b_head)) { /* Detect basic blocks with nothing but a label. This can happen in particular at the end of a function. */ if (b_head == b_end) b_empty = 1; del_first = del_last = b_head; b_head = NEXT_INSN (b_head); } /* Delete the basic block note and handle blocks containing just that note. */ if (NOTE_INSN_BASIC_BLOCK_P (b_head)) { if (b_head == b_end) b_empty = 1; if (! del_last) del_first = b_head; del_last = b_head; b_head = NEXT_INSN (b_head); } /* If there was a jump out of A, delete it. */ if (JUMP_P (a_end)) { rtx prev; for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev)) if (!NOTE_P (prev) || NOTE_INSN_BASIC_BLOCK_P (prev) || prev == BB_HEAD (a)) break; del_first = a_end; #ifdef HAVE_cc0 /* If this was a conditional jump, we need to also delete the insn that set cc0. */ if (only_sets_cc0_p (prev)) { rtx tmp = prev; prev = prev_nonnote_insn (prev); if (!prev) prev = BB_HEAD (a); del_first = tmp; } #endif a_end = PREV_INSN (del_first); } else if (BARRIER_P (NEXT_INSN (a_end))) del_first = NEXT_INSN (a_end); /* Delete everything marked above as well as crap that might be hanging out between the two blocks. */ BB_HEAD (b) = NULL; delete_insn_chain (del_first, del_last, true); /* Reassociate the insns of B with A. */ if (!b_empty) { update_bb_for_insn_chain (a_end, b_debug_end, a); a_end = b_debug_end; } else if (b_end != b_debug_end) { /* Move any deleted labels and other notes between the end of A and the debug insns that make up B after the debug insns, bringing the debug insns into A while keeping the notes after the end of A. */ if (NEXT_INSN (a_end) != b_debug_start) reorder_insns_nobb (NEXT_INSN (a_end), PREV_INSN (b_debug_start), b_debug_end); update_bb_for_insn_chain (b_debug_start, b_debug_end, a); a_end = b_debug_end; } df_bb_delete (b->index); BB_END (a) = a_end; } /* Return true when block A and B can be merged. */ static bool rtl_can_merge_blocks (basic_block a, basic_block b) { /* If we are partitioning hot/cold basic blocks, we don't want to mess up unconditional or indirect jumps that cross between hot and cold sections. Basic block partitioning may result in some jumps that appear to be optimizable (or blocks that appear to be mergeable), but which really must be left untouched (they are required to make it safely across partition boundaries). See the comments at the top of bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ if (BB_PARTITION (a) != BB_PARTITION (b)) return false; /* There must be exactly one edge in between the blocks. */ return (single_succ_p (a) && single_succ (a) == b && single_pred_p (b) && a != b /* Must be simple edge. */ && !(single_succ_edge (a)->flags & EDGE_COMPLEX) && a->next_bb == b && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR /* If the jump insn has side effects, we can't kill the edge. */ && (!JUMP_P (BB_END (a)) || (reload_completed ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a))))); } /* Return the label in the head of basic block BLOCK. Create one if it doesn't exist. */ rtx block_label (basic_block block) { if (block == EXIT_BLOCK_PTR) return NULL_RTX; if (!LABEL_P (BB_HEAD (block))) { BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block)); } return BB_HEAD (block); } /* Attempt to perform edge redirection by replacing possibly complex jump instruction by unconditional jump or removing jump completely. This can apply only if all edges now point to the same block. The parameters and return values are equivalent to redirect_edge_and_branch. */ edge try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout) { basic_block src = e->src; rtx insn = BB_END (src), kill_from; rtx set; int fallthru = 0; /* If we are partitioning hot/cold basic blocks, we don't want to mess up unconditional or indirect jumps that cross between hot and cold sections. Basic block partitioning may result in some jumps that appear to be optimizable (or blocks that appear to be mergeable), but which really must be left untouched (they are required to make it safely across partition boundaries). See the comments at the top of bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX) || BB_PARTITION (src) != BB_PARTITION (target)) return NULL; /* We can replace or remove a complex jump only when we have exactly two edges. Also, if we have exactly one outgoing edge, we can redirect that. */ if (EDGE_COUNT (src->succs) >= 3 /* Verify that all targets will be TARGET. Specifically, the edge that is not E must also go to TARGET. */ || (EDGE_COUNT (src->succs) == 2 && EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target)) return NULL; if (!onlyjump_p (insn)) return NULL; if ((!optimize || reload_completed) && tablejump_p (insn, NULL, NULL)) return NULL; /* Avoid removing branch with side effects. */ set = single_set (insn); if (!set || side_effects_p (set)) return NULL; /* In case we zap a conditional jump, we'll need to kill the cc0 setter too. */ kill_from = insn; #ifdef HAVE_cc0 if (reg_mentioned_p (cc0_rtx, PATTERN (insn)) && only_sets_cc0_p (PREV_INSN (insn))) kill_from = PREV_INSN (insn); #endif /* See if we can create the fallthru edge. */ if (in_cfglayout || can_fallthru (src, target)) { if (dump_file) fprintf (dump_file, "Removing jump %i.\n", INSN_UID (insn)); fallthru = 1; /* Selectively unlink whole insn chain. */ if (in_cfglayout) { rtx insn = src->il.rtl->footer; delete_insn_chain (kill_from, BB_END (src), false); /* Remove barriers but keep jumptables. */ while (insn) { if (BARRIER_P (insn)) { if (PREV_INSN (insn)) NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn); else src->il.rtl->footer = NEXT_INSN (insn); if (NEXT_INSN (insn)) PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn); } if (LABEL_P (insn)) break; insn = NEXT_INSN (insn); } } else delete_insn_chain (kill_from, PREV_INSN (BB_HEAD (target)), false); } /* If this already is simplejump, redirect it. */ else if (simplejump_p (insn)) { if (e->dest == target) return NULL; if (dump_file) fprintf (dump_file, "Redirecting jump %i from %i to %i.\n", INSN_UID (insn), e->dest->index, target->index); if (!redirect_jump (insn, block_label (target), 0)) { gcc_assert (target == EXIT_BLOCK_PTR); return NULL; } } /* Cannot do anything for target exit block. */ else if (target == EXIT_BLOCK_PTR) return NULL; /* Or replace possibly complicated jump insn by simple jump insn. */ else { rtx target_label = block_label (target); rtx barrier, label, table; emit_jump_insn_after_noloc (gen_jump (target_label), insn); JUMP_LABEL (BB_END (src)) = target_label; LABEL_NUSES (target_label)++; if (dump_file) fprintf (dump_file, "Replacing insn %i by jump %i\n", INSN_UID (insn), INSN_UID (BB_END (src))); delete_insn_chain (kill_from, insn, false); /* Recognize a tablejump that we are converting to a simple jump and remove its associated CODE_LABEL and ADDR_VEC or ADDR_DIFF_VEC. */ if (tablejump_p (insn, &label, &table)) delete_insn_chain (label, table, false); barrier = next_nonnote_insn (BB_END (src)); if (!barrier || !BARRIER_P (barrier)) emit_barrier_after (BB_END (src)); else { if (barrier != NEXT_INSN (BB_END (src))) { /* Move the jump before barrier so that the notes which originally were or were created before jump table are inside the basic block. */ rtx new_insn = BB_END (src); update_bb_for_insn_chain (NEXT_INSN (BB_END (src)), PREV_INSN (barrier), src); NEXT_INSN (PREV_INSN (new_insn)) = NEXT_INSN (new_insn); PREV_INSN (NEXT_INSN (new_insn)) = PREV_INSN (new_insn); NEXT_INSN (new_insn) = barrier; NEXT_INSN (PREV_INSN (barrier)) = new_insn; PREV_INSN (new_insn) = PREV_INSN (barrier); PREV_INSN (barrier) = new_insn; } } } /* Keep only one edge out and set proper flags. */ if (!single_succ_p (src)) remove_edge (e); gcc_assert (single_succ_p (src)); e = single_succ_edge (src); if (fallthru) e->flags = EDGE_FALLTHRU; else e->flags = 0; e->probability = REG_BR_PROB_BASE; e->count = src->count; if (e->dest != target) redirect_edge_succ (e, target); return e; } /* Subroutine of redirect_branch_edge that tries to patch the jump instruction INSN so that it reaches block NEW. Do this only when it originally reached block OLD. Return true if this worked or the original target wasn't OLD, return false if redirection doesn't work. */ static bool patch_jump_insn (rtx insn, rtx old_label, basic_block new_bb) { rtx tmp; /* Recognize a tablejump and adjust all matching cases. */ if (tablejump_p (insn, NULL, &tmp)) { rtvec vec; int j; rtx new_label = block_label (new_bb); if (new_bb == EXIT_BLOCK_PTR) return false; if (GET_CODE (PATTERN (tmp)) == ADDR_VEC) vec = XVEC (PATTERN (tmp), 0); else vec = XVEC (PATTERN (tmp), 1); for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j) if (XEXP (RTVEC_ELT (vec, j), 0) == old_label) { RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label); --LABEL_NUSES (old_label); ++LABEL_NUSES (new_label); } /* Handle casesi dispatch insns. */ if ((tmp = single_set (insn)) != NULL && SET_DEST (tmp) == pc_rtx && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label) { XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (Pmode, new_label); --LABEL_NUSES (old_label); ++LABEL_NUSES (new_label); } } else if ((tmp = extract_asm_operands (PATTERN (insn))) != NULL) { int i, n = ASM_OPERANDS_LABEL_LENGTH (tmp); rtx new_label, note; if (new_bb == EXIT_BLOCK_PTR) return false; new_label = block_label (new_bb); for (i = 0; i < n; ++i) { rtx old_ref = ASM_OPERANDS_LABEL (tmp, i); gcc_assert (GET_CODE (old_ref) == LABEL_REF); if (XEXP (old_ref, 0) == old_label) { ASM_OPERANDS_LABEL (tmp, i) = gen_rtx_LABEL_REF (Pmode, new_label); --LABEL_NUSES (old_label); ++LABEL_NUSES (new_label); } } if (JUMP_LABEL (insn) == old_label) { JUMP_LABEL (insn) = new_label; note = find_reg_note (insn, REG_LABEL_TARGET, new_label); if (note) remove_note (insn, note); } else { note = find_reg_note (insn, REG_LABEL_TARGET, old_label); if (note) remove_note (insn, note); if (JUMP_LABEL (insn) != new_label && !find_reg_note (insn, REG_LABEL_TARGET, new_label)) add_reg_note (insn, REG_LABEL_TARGET, new_label); } while ((note = find_reg_note (insn, REG_LABEL_OPERAND, old_label)) != NULL_RTX) XEXP (note, 0) = new_label; } else { /* ?? We may play the games with moving the named labels from one basic block to the other in case only one computed_jump is available. */ if (computed_jump_p (insn) /* A return instruction can't be redirected. */ || returnjump_p (insn)) return false; if (!currently_expanding_to_rtl || JUMP_LABEL (insn) == old_label) { /* If the insn doesn't go where we think, we're confused. */ gcc_assert (JUMP_LABEL (insn) == old_label); /* If the substitution doesn't succeed, die. This can happen if the back end emitted unrecognizable instructions or if target is exit block on some arches. */ if (!redirect_jump (insn, block_label (new_bb), 0)) { gcc_assert (new_bb == EXIT_BLOCK_PTR); return false; } } } return true; } /* Redirect edge representing branch of (un)conditional jump or tablejump, NULL on failure */ static edge redirect_branch_edge (edge e, basic_block target) { rtx old_label = BB_HEAD (e->dest); basic_block src = e->src; rtx insn = BB_END (src); /* We can only redirect non-fallthru edges of jump insn. */ if (e->flags & EDGE_FALLTHRU) return NULL; else if (!JUMP_P (insn) && !currently_expanding_to_rtl) return NULL; if (!currently_expanding_to_rtl) { if (!patch_jump_insn (insn, old_label, target)) return NULL; } else /* When expanding this BB might actually contain multiple jumps (i.e. not yet split by find_many_sub_basic_blocks). Redirect all of those that match our label. */ for (insn = BB_HEAD (src); insn != NEXT_INSN (BB_END (src)); insn = NEXT_INSN (insn)) if (JUMP_P (insn) && !patch_jump_insn (insn, old_label, target)) return NULL; if (dump_file) fprintf (dump_file, "Edge %i->%i redirected to %i\n", e->src->index, e->dest->index, target->index); if (e->dest != target) e = redirect_edge_succ_nodup (e, target); return e; } /* Attempt to change code to redirect edge E to TARGET. Don't do that on expense of adding new instructions or reordering basic blocks. Function can be also called with edge destination equivalent to the TARGET. Then it should try the simplifications and do nothing if none is possible. Return edge representing the branch if transformation succeeded. Return NULL on failure. We still return NULL in case E already destinated TARGET and we didn't managed to simplify instruction stream. */ static edge rtl_redirect_edge_and_branch (edge e, basic_block target) { edge ret; basic_block src = e->src; if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH)) return NULL; if (e->dest == target) return e; if ((ret = try_redirect_by_replacing_jump (e, target, false)) != NULL) { df_set_bb_dirty (src); return ret; } ret = redirect_branch_edge (e, target); if (!ret) return NULL; df_set_bb_dirty (src); return ret; } /* Like force_nonfallthru below, but additionally performs redirection Used by redirect_edge_and_branch_force. */ static basic_block force_nonfallthru_and_redirect (edge e, basic_block target) { basic_block jump_block, new_bb = NULL, src = e->src; rtx note; edge new_edge; int abnormal_edge_flags = 0; int loc; /* In the case the last instruction is conditional jump to the next instruction, first redirect the jump itself and then continue by creating a basic block afterwards to redirect fallthru edge. */ if (e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR && any_condjump_p (BB_END (e->src)) && JUMP_LABEL (BB_END (e->src)) == BB_HEAD (e->dest)) { rtx note; edge b = unchecked_make_edge (e->src, target, 0); bool redirected; redirected = redirect_jump (BB_END (e->src), block_label (target), 0); gcc_assert (redirected); note = find_reg_note (BB_END (e->src), REG_BR_PROB, NULL_RTX); if (note) { int prob = INTVAL (XEXP (note, 0)); b->probability = prob; b->count = e->count * prob / REG_BR_PROB_BASE; e->probability -= e->probability; e->count -= b->count; if (e->probability < 0) e->probability = 0; if (e->count < 0) e->count = 0; } } if (e->flags & EDGE_ABNORMAL) { /* Irritating special case - fallthru edge to the same block as abnormal edge. We can't redirect abnormal edge, but we still can split the fallthru one and create separate abnormal edge to original destination. This allows bb-reorder to make such edge non-fallthru. */ gcc_assert (e->dest == target); abnormal_edge_flags = e->flags & ~(EDGE_FALLTHRU | EDGE_CAN_FALLTHRU); e->flags &= EDGE_FALLTHRU | EDGE_CAN_FALLTHRU; } else { gcc_assert (e->flags & EDGE_FALLTHRU); if (e->src == ENTRY_BLOCK_PTR) { /* We can't redirect the entry block. Create an empty block at the start of the function which we use to add the new jump. */ edge tmp; edge_iterator ei; bool found = false; basic_block bb = create_basic_block (BB_HEAD (e->dest), NULL, ENTRY_BLOCK_PTR); /* Change the existing edge's source to be the new block, and add a new edge from the entry block to the new block. */ e->src = bb; for (ei = ei_start (ENTRY_BLOCK_PTR->succs); (tmp = ei_safe_edge (ei)); ) { if (tmp == e) { VEC_unordered_remove (edge, ENTRY_BLOCK_PTR->succs, ei.index); found = true; break; } else ei_next (&ei); } gcc_assert (found); VEC_safe_push (edge, gc, bb->succs, e); make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU); } } if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags) { /* Create the new structures. */ /* If the old block ended with a tablejump, skip its table by searching forward from there. Otherwise start searching forward from the last instruction of the old block. */ if (!tablejump_p (BB_END (e->src), NULL, ¬e)) note = BB_END (e->src); note = NEXT_INSN (note); jump_block = create_basic_block (note, NULL, e->src); jump_block->count = e->count; jump_block->frequency = EDGE_FREQUENCY (e); jump_block->loop_depth = target->loop_depth; /* Make sure new block ends up in correct hot/cold section. */ BB_COPY_PARTITION (jump_block, e->src); if (flag_reorder_blocks_and_partition && targetm.have_named_sections && JUMP_P (BB_END (jump_block)) && !any_condjump_p (BB_END (jump_block)) && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING)) add_reg_note (BB_END (jump_block), REG_CROSSING_JUMP, NULL_RTX); /* Wire edge in. */ new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU); new_edge->probability = e->probability; new_edge->count = e->count; /* Redirect old edge. */ redirect_edge_pred (e, jump_block); e->probability = REG_BR_PROB_BASE; new_bb = jump_block; } else jump_block = e->src; if (e->goto_locus && e->goto_block == NULL) loc = e->goto_locus; else loc = 0; e->flags &= ~EDGE_FALLTHRU; if (target == EXIT_BLOCK_PTR) { #ifdef HAVE_return emit_jump_insn_after_setloc (gen_return (), BB_END (jump_block), loc); #else gcc_unreachable (); #endif } else { rtx label = block_label (target); emit_jump_insn_after_setloc (gen_jump (label), BB_END (jump_block), loc); JUMP_LABEL (BB_END (jump_block)) = label; LABEL_NUSES (label)++; } emit_barrier_after (BB_END (jump_block)); redirect_edge_succ_nodup (e, target); if (abnormal_edge_flags) make_edge (src, target, abnormal_edge_flags); df_mark_solutions_dirty (); return new_bb; } /* Edge E is assumed to be fallthru edge. Emit needed jump instruction (and possibly create new basic block) to make edge non-fallthru. Return newly created BB or NULL if none. */ basic_block force_nonfallthru (edge e) { return force_nonfallthru_and_redirect (e, e->dest); } /* Redirect edge even at the expense of creating new jump insn or basic block. Return new basic block if created, NULL otherwise. Conversion must be possible. */ static basic_block rtl_redirect_edge_and_branch_force (edge e, basic_block target) { if (redirect_edge_and_branch (e, target) || e->dest == target) return NULL; /* In case the edge redirection failed, try to force it to be non-fallthru and redirect newly created simplejump. */ df_set_bb_dirty (e->src); return force_nonfallthru_and_redirect (e, target); } /* The given edge should potentially be a fallthru edge. If that is in fact true, delete the jump and barriers that are in the way. */ static void rtl_tidy_fallthru_edge (edge e) { rtx q; basic_block b = e->src, c = b->next_bb; /* ??? In a late-running flow pass, other folks may have deleted basic blocks by nopping out blocks, leaving multiple BARRIERs between here and the target label. They ought to be chastised and fixed. We can also wind up with a sequence of undeletable labels between one block and the next. So search through a sequence of barriers, labels, and notes for the head of block C and assert that we really do fall through. */ for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q)) if (INSN_P (q)) return; /* Remove what will soon cease being the jump insn from the source block. If block B consisted only of this single jump, turn it into a deleted note. */ q = BB_END (b); if (JUMP_P (q) && onlyjump_p (q) && (any_uncondjump_p (q) || single_succ_p (b))) { #ifdef HAVE_cc0 /* If this was a conditional jump, we need to also delete the insn that set cc0. */ if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q))) q = PREV_INSN (q); #endif q = PREV_INSN (q); } /* Selectively unlink the sequence. */ if (q != PREV_INSN (BB_HEAD (c))) delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)), false); e->flags |= EDGE_FALLTHRU; } /* Should move basic block BB after basic block AFTER. NIY. */ static bool rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED, basic_block after ATTRIBUTE_UNUSED) { return false; } /* Split a (typically critical) edge. Return the new block. The edge must not be abnormal. ??? The code generally expects to be called on critical edges. The case of a block ending in an unconditional jump to a block with multiple predecessors is not handled optimally. */ static basic_block rtl_split_edge (edge edge_in) { basic_block bb; rtx before; /* Abnormal edges cannot be split. */ gcc_assert (!(edge_in->flags & EDGE_ABNORMAL)); /* We are going to place the new block in front of edge destination. Avoid existence of fallthru predecessors. */ if ((edge_in->flags & EDGE_FALLTHRU) == 0) { edge e; edge_iterator ei; FOR_EACH_EDGE (e, ei, edge_in->dest->preds) if (e->flags & EDGE_FALLTHRU) break; if (e) force_nonfallthru (e); } /* Create the basic block note. */ if (edge_in->dest != EXIT_BLOCK_PTR) before = BB_HEAD (edge_in->dest); else before = NULL_RTX; /* If this is a fall through edge to the exit block, the blocks might be not adjacent, and the right place is the after the source. */ if (edge_in->flags & EDGE_FALLTHRU && edge_in->dest == EXIT_BLOCK_PTR) { before = NEXT_INSN (BB_END (edge_in->src)); bb = create_basic_block (before, NULL, edge_in->src); BB_COPY_PARTITION (bb, edge_in->src); } else { bb = create_basic_block (before, NULL, edge_in->dest->prev_bb); /* ??? Why not edge_in->dest->prev_bb here? */ BB_COPY_PARTITION (bb, edge_in->dest); } make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU); /* For non-fallthru edges, we must adjust the predecessor's jump instruction to target our new block. */ if ((edge_in->flags & EDGE_FALLTHRU) == 0) { edge redirected = redirect_edge_and_branch (edge_in, bb); gcc_assert (redirected); } else { if (edge_in->src != ENTRY_BLOCK_PTR) { /* For asm goto even splitting of fallthru edge might need insn patching, as other labels might point to the old label. */ rtx last = BB_END (edge_in->src); if (last && JUMP_P (last) && edge_in->dest != EXIT_BLOCK_PTR && extract_asm_operands (PATTERN (last)) != NULL_RTX && patch_jump_insn (last, before, bb)) df_set_bb_dirty (edge_in->src); } redirect_edge_succ (edge_in, bb); } return bb; } /* Queue instructions for insertion on an edge between two basic blocks. The new instructions and basic blocks (if any) will not appear in the CFG until commit_edge_insertions is called. */ void insert_insn_on_edge (rtx pattern, edge e) { /* We cannot insert instructions on an abnormal critical edge. It will be easier to find the culprit if we die now. */ gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e))); if (e->insns.r == NULL_RTX) start_sequence (); else push_to_sequence (e->insns.r); emit_insn (pattern); e->insns.r = get_insns (); end_sequence (); } /* Update the CFG for the instructions queued on edge E. */ void commit_one_edge_insertion (edge e) { rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last; basic_block bb = NULL; /* Pull the insns off the edge now since the edge might go away. */ insns = e->insns.r; e->insns.r = NULL_RTX; if (!before && !after) { /* Figure out where to put these things. If the destination has one predecessor, insert there. Except for the exit block. */ if (single_pred_p (e->dest) && e->dest != EXIT_BLOCK_PTR) { bb = e->dest; /* Get the location correct wrt a code label, and "nice" wrt a basic block note, and before everything else. */ tmp = BB_HEAD (bb); if (LABEL_P (tmp)) tmp = NEXT_INSN (tmp); if (NOTE_INSN_BASIC_BLOCK_P (tmp)) tmp = NEXT_INSN (tmp); if (tmp == BB_HEAD (bb)) before = tmp; else if (tmp) after = PREV_INSN (tmp); else after = get_last_insn (); } /* If the source has one successor and the edge is not abnormal, insert there. Except for the entry block. */ else if ((e->flags & EDGE_ABNORMAL) == 0 && single_succ_p (e->src) && e->src != ENTRY_BLOCK_PTR) { bb = e->src; /* It is possible to have a non-simple jump here. Consider a target where some forms of unconditional jumps clobber a register. This happens on the fr30 for example. We know this block has a single successor, so we can just emit the queued insns before the jump. */ if (JUMP_P (BB_END (bb))) before = BB_END (bb); else { /* We'd better be fallthru, or we've lost track of what's what. */ gcc_assert (e->flags & EDGE_FALLTHRU); after = BB_END (bb); } } /* Otherwise we must split the edge. */ else { bb = split_edge (e); after = BB_END (bb); if (flag_reorder_blocks_and_partition && targetm.have_named_sections && e->src != ENTRY_BLOCK_PTR && BB_PARTITION (e->src) == BB_COLD_PARTITION && !(e->flags & EDGE_CROSSING) && JUMP_P (after) && !any_condjump_p (after) && (single_succ_edge (bb)->flags & EDGE_CROSSING)) add_reg_note (after, REG_CROSSING_JUMP, NULL_RTX); } } /* Now that we've found the spot, do the insertion. */ if (before) { emit_insn_before_noloc (insns, before, bb); last = prev_nonnote_insn (before); } else last = emit_insn_after_noloc (insns, after, bb); if (returnjump_p (last)) { /* ??? Remove all outgoing edges from BB and add one for EXIT. This is not currently a problem because this only happens for the (single) epilogue, which already has a fallthru edge to EXIT. */ e = single_succ_edge (bb); gcc_assert (e->dest == EXIT_BLOCK_PTR && single_succ_p (bb) && (e->flags & EDGE_FALLTHRU)); e->flags &= ~EDGE_FALLTHRU; emit_barrier_after (last); if (before) delete_insn (before); } else gcc_assert (!JUMP_P (last)); /* Mark the basic block for find_many_sub_basic_blocks. */ if (current_ir_type () != IR_RTL_CFGLAYOUT) bb->aux = &bb->aux; } /* Update the CFG for all queued instructions. */ void commit_edge_insertions (void) { basic_block bb; sbitmap blocks; bool changed = false; #ifdef ENABLE_CHECKING verify_flow_info (); #endif FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb) { edge e; edge_iterator ei; FOR_EACH_EDGE (e, ei, bb->succs) if (e->insns.r) { changed = true; commit_one_edge_insertion (e); } } if (!changed) return; /* In the old rtl CFG API, it was OK to insert control flow on an edge, apparently? In cfglayout mode, this will *not* work, and the caller is responsible for making sure that control flow is valid at all times. */ if (current_ir_type () == IR_RTL_CFGLAYOUT) return; blocks = sbitmap_alloc (last_basic_block); sbitmap_zero (blocks); FOR_EACH_BB (bb) if (bb->aux) { SET_BIT (blocks, bb->index); /* Check for forgotten bb->aux values before commit_edge_insertions call. */ gcc_assert (bb->aux == &bb->aux); bb->aux = NULL; } find_many_sub_basic_blocks (blocks); sbitmap_free (blocks); } /* Print out RTL-specific basic block information (live information at start and end). */ static void rtl_dump_bb (basic_block bb, FILE *outf, int indent, int flags ATTRIBUTE_UNUSED) { rtx insn; rtx last; char *s_indent; s_indent = (char *) alloca ((size_t) indent + 1); memset (s_indent, ' ', (size_t) indent); s_indent[indent] = '\0'; if (df) { df_dump_top (bb, outf); putc ('\n', outf); } for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last; insn = NEXT_INSN (insn)) print_rtl_single (outf, insn); if (df) { df_dump_bottom (bb, outf); putc ('\n', outf); } } /* Like print_rtl, but also print out live information for the start of each basic block. */ void print_rtl_with_bb (FILE *outf, const_rtx rtx_first) { const_rtx tmp_rtx; if (rtx_first == 0) fprintf (outf, "(nil)\n"); else { enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB }; int max_uid = get_max_uid (); basic_block *start = XCNEWVEC (basic_block, max_uid); basic_block *end = XCNEWVEC (basic_block, max_uid); enum bb_state *in_bb_p = XCNEWVEC (enum bb_state, max_uid); basic_block bb; if (df) df_dump_start (outf); FOR_EACH_BB_REVERSE (bb) { rtx x; start[INSN_UID (BB_HEAD (bb))] = bb; end[INSN_UID (BB_END (bb))] = bb; for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x)) { enum bb_state state = IN_MULTIPLE_BB; if (in_bb_p[INSN_UID (x)] == NOT_IN_BB) state = IN_ONE_BB; in_bb_p[INSN_UID (x)] = state; if (x == BB_END (bb)) break; } } for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx)) { int did_output; if ((bb = start[INSN_UID (tmp_rtx)]) != NULL) { edge e; edge_iterator ei; fprintf (outf, ";; Start of basic block ("); FOR_EACH_EDGE (e, ei, bb->preds) fprintf (outf, " %d", e->src->index); fprintf (outf, ") -> %d\n", bb->index); if (df) { df_dump_top (bb, outf); putc ('\n', outf); } FOR_EACH_EDGE (e, ei, bb->preds) { fputs (";; Pred edge ", outf); dump_edge_info (outf, e, 0); fputc ('\n', outf); } } if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB && !NOTE_P (tmp_rtx) && !BARRIER_P (tmp_rtx)) fprintf (outf, ";; Insn is not within a basic block\n"); else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB) fprintf (outf, ";; Insn is in multiple basic blocks\n"); did_output = print_rtl_single (outf, tmp_rtx); if ((bb = end[INSN_UID (tmp_rtx)]) != NULL) { edge e; edge_iterator ei; fprintf (outf, ";; End of basic block %d -> (", bb->index); FOR_EACH_EDGE (e, ei, bb->succs) fprintf (outf, " %d", e->dest->index); fprintf (outf, ")\n"); if (df) { df_dump_bottom (bb, outf); putc ('\n', outf); } putc ('\n', outf); FOR_EACH_EDGE (e, ei, bb->succs) { fputs (";; Succ edge ", outf); dump_edge_info (outf, e, 1); fputc ('\n', outf); } } if (did_output) putc ('\n', outf); } free (start); free (end); free (in_bb_p); } if (crtl->epilogue_delay_list != 0) { fprintf (outf, "\n;; Insns in epilogue delay list:\n\n"); for (tmp_rtx = crtl->epilogue_delay_list; tmp_rtx != 0; tmp_rtx = XEXP (tmp_rtx, 1)) print_rtl_single (outf, XEXP (tmp_rtx, 0)); } } void update_br_prob_note (basic_block bb) { rtx note; if (!JUMP_P (BB_END (bb))) return; note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX); if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability) return; XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability); } /* Get the last insn associated with block BB (that includes barriers and tablejumps after BB). */ rtx get_last_bb_insn (basic_block bb) { rtx tmp; rtx end = BB_END (bb); /* Include any jump table following the basic block. */ if (tablejump_p (end, NULL, &tmp)) end = tmp; /* Include any barriers that may follow the basic block. */ tmp = next_nonnote_insn_bb (end); while (tmp && BARRIER_P (tmp)) { end = tmp; tmp = next_nonnote_insn_bb (end); } return end; } /* Verify the CFG and RTL consistency common for both underlying RTL and cfglayout RTL. Currently it does following checks: - overlapping of basic blocks - insns with wrong BLOCK_FOR_INSN pointers - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note) - tails of basic blocks (ensure that boundary is necessary) - scans body of the basic block for JUMP_INSN, CODE_LABEL and NOTE_INSN_BASIC_BLOCK - verify that no fall_thru edge crosses hot/cold partition boundaries - verify that there are no pending RTL branch predictions In future it can be extended check a lot of other stuff as well (reachability of basic blocks, life information, etc. etc.). */ static int rtl_verify_flow_info_1 (void) { rtx x; int err = 0; basic_block bb; /* Check the general integrity of the basic blocks. */ FOR_EACH_BB_REVERSE (bb) { rtx insn; if (!(bb->flags & BB_RTL)) { error ("BB_RTL flag not set for block %d", bb->index); err = 1; } FOR_BB_INSNS (bb, insn) if (BLOCK_FOR_INSN (insn) != bb) { error ("insn %d basic block pointer is %d, should be %d", INSN_UID (insn), BLOCK_FOR_INSN (insn) ? BLOCK_FOR_INSN (insn)->index : 0, bb->index); err = 1; } for (insn = bb->il.rtl->header; insn; insn = NEXT_INSN (insn)) if (!BARRIER_P (insn) && BLOCK_FOR_INSN (insn) != NULL) { error ("insn %d in header of bb %d has non-NULL basic block", INSN_UID (insn), bb->index); err = 1; } for (insn = bb->il.rtl->footer; insn; insn = NEXT_INSN (insn)) if (!BARRIER_P (insn) && BLOCK_FOR_INSN (insn) != NULL) { error ("insn %d in footer of bb %d has non-NULL basic block", INSN_UID (insn), bb->index); err = 1; } } /* Now check the basic blocks (boundaries etc.) */ FOR_EACH_BB_REVERSE (bb) { int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0; edge e, fallthru = NULL; rtx note; edge_iterator ei; if (JUMP_P (BB_END (bb)) && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX)) && EDGE_COUNT (bb->succs) >= 2 && any_condjump_p (BB_END (bb))) { if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability && profile_status != PROFILE_ABSENT) { error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i", INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability); err = 1; } } FOR_EACH_EDGE (e, ei, bb->succs) { if (e->flags & EDGE_FALLTHRU) { n_fallthru++, fallthru = e; if ((e->flags & EDGE_CROSSING) || (BB_PARTITION (e->src) != BB_PARTITION (e->dest) && e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR)) { error ("fallthru edge crosses section boundary (bb %i)", e->src->index); err = 1; } } if ((e->flags & ~(EDGE_DFS_BACK | EDGE_CAN_FALLTHRU | EDGE_IRREDUCIBLE_LOOP | EDGE_LOOP_EXIT | EDGE_CROSSING)) == 0) n_branch++; if (e->flags & EDGE_ABNORMAL_CALL) n_call++; if (e->flags & EDGE_EH) n_eh++; else if (e->flags & EDGE_ABNORMAL) n_abnormal++; } if (n_eh && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX)) { error ("missing REG_EH_REGION note in the end of bb %i", bb->index); err = 1; } if (n_eh > 1) { error ("too many eh edges %i", bb->index); err = 1; } if (n_branch && (!JUMP_P (BB_END (bb)) || (n_branch > 1 && (any_uncondjump_p (BB_END (bb)) || any_condjump_p (BB_END (bb)))))) { error ("too many outgoing branch edges from bb %i", bb->index); err = 1; } if (n_fallthru && any_uncondjump_p (BB_END (bb))) { error ("fallthru edge after unconditional jump %i", bb->index); err = 1; } if (n_branch != 1 && any_uncondjump_p (BB_END (bb))) { error ("wrong number of branch edges after unconditional jump %i", bb->index); err = 1; } if (n_branch != 1 && any_condjump_p (BB_END (bb)) && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest)) { error ("wrong amount of branch edges after conditional jump %i", bb->index); err = 1; } if (n_call && !CALL_P (BB_END (bb))) { error ("call edges for non-call insn in bb %i", bb->index); err = 1; } if (n_abnormal && (!CALL_P (BB_END (bb)) && n_call != n_abnormal) && (!JUMP_P (BB_END (bb)) || any_condjump_p (BB_END (bb)) || any_uncondjump_p (BB_END (bb)))) { error ("abnormal edges for no purpose in bb %i", bb->index); err = 1; } for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x)) /* We may have a barrier inside a basic block before dead code elimination. There is no BLOCK_FOR_INSN field in a barrier. */ if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb) { debug_rtx (x); if (! BLOCK_FOR_INSN (x)) error ("insn %d inside basic block %d but block_for_insn is NULL", INSN_UID (x), bb->index); else error ("insn %d inside basic block %d but block_for_insn is %i", INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index); err = 1; } /* OK pointers are correct. Now check the header of basic block. It ought to contain optional CODE_LABEL followed by NOTE_BASIC_BLOCK. */ x = BB_HEAD (bb); if (LABEL_P (x)) { if (BB_END (bb) == x) { error ("NOTE_INSN_BASIC_BLOCK is missing for block %d", bb->index); err = 1; } x = NEXT_INSN (x); } if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb) { error ("NOTE_INSN_BASIC_BLOCK is missing for block %d", bb->index); err = 1; } if (BB_END (bb) == x) /* Do checks for empty blocks here. */ ; else for (x = NEXT_INSN (x); x; x = NEXT_INSN (x)) { if (NOTE_INSN_BASIC_BLOCK_P (x)) { error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d", INSN_UID (x), bb->index); err = 1; } if (x == BB_END (bb)) break; if (control_flow_insn_p (x)) { error ("in basic block %d:", bb->index); fatal_insn ("flow control insn inside a basic block", x); } } } /* Clean up. */ return err; } /* Verify the CFG and RTL consistency common for both underlying RTL and cfglayout RTL. Currently it does following checks: - all checks of rtl_verify_flow_info_1 - test head/end pointers - check that all insns are in the basic blocks (except the switch handling code, barriers and notes) - check that all returns are followed by barriers - check that all fallthru edge points to the adjacent blocks. */ static int rtl_verify_flow_info (void) { basic_block bb; int err = rtl_verify_flow_info_1 (); rtx x; rtx last_head = get_last_insn (); basic_block *bb_info; int num_bb_notes; const rtx rtx_first = get_insns (); basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL; const int max_uid = get_max_uid (); bb_info = XCNEWVEC (basic_block, max_uid); FOR_EACH_BB_REVERSE (bb) { edge e; edge_iterator ei; rtx head = BB_HEAD (bb); rtx end = BB_END (bb); for (x = last_head; x != NULL_RTX; x = PREV_INSN (x)) { /* Verify the end of the basic block is in the INSN chain. */ if (x == end) break; /* And that the code outside of basic blocks has NULL bb field. */ if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != NULL) { error ("insn %d outside of basic blocks has non-NULL bb field", INSN_UID (x)); err = 1; } } if (!x) { error ("end insn %d for block %d not found in the insn stream", INSN_UID (end), bb->index); err = 1; } /* Work backwards from the end to the head of the basic block to verify the head is in the RTL chain. */ for (; x != NULL_RTX; x = PREV_INSN (x)) { /* While walking over the insn chain, verify insns appear in only one basic block. */ if (bb_info[INSN_UID (x)] != NULL) { error ("insn %d is in multiple basic blocks (%d and %d)", INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index); err = 1; } bb_info[INSN_UID (x)] = bb; if (x == head) break; } if (!x) { error ("head insn %d for block %d not found in the insn stream", INSN_UID (head), bb->index); err = 1; } last_head = PREV_INSN (x); FOR_EACH_EDGE (e, ei, bb->succs) if (e->flags & EDGE_FALLTHRU) break; if (!e) { rtx insn; /* Ensure existence of barrier in BB with no fallthru edges. */ for (insn = NEXT_INSN (BB_END (bb)); ; insn = NEXT_INSN (insn)) { if (!insn || NOTE_INSN_BASIC_BLOCK_P (insn)) { error ("missing barrier after block %i", bb->index); err = 1; break; } if (BARRIER_P (insn)) break; } } else if (e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR) { rtx insn; if (e->src->next_bb != e->dest) { error ("verify_flow_info: Incorrect blocks for fallthru %i->%i", e->src->index, e->dest->index); err = 1; } else for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest); insn = NEXT_INSN (insn)) if (BARRIER_P (insn) || INSN_P (insn)) { error ("verify_flow_info: Incorrect fallthru %i->%i", e->src->index, e->dest->index); fatal_insn ("wrong insn in the fallthru edge", insn); err = 1; } } } for (x = last_head; x != NULL_RTX; x = PREV_INSN (x)) { /* Check that the code before the first basic block has NULL bb field. */ if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != NULL) { error ("insn %d outside of basic blocks has non-NULL bb field", INSN_UID (x)); err = 1; } } free (bb_info); num_bb_notes = 0; last_bb_seen = ENTRY_BLOCK_PTR; for (x = rtx_first; x; x = NEXT_INSN (x)) { if (NOTE_INSN_BASIC_BLOCK_P (x)) { bb = NOTE_BASIC_BLOCK (x); num_bb_notes++; if (bb != last_bb_seen->next_bb) internal_error ("basic blocks not laid down consecutively"); curr_bb = last_bb_seen = bb; } if (!curr_bb) { switch (GET_CODE (x)) { case BARRIER: case NOTE: break; case CODE_LABEL: /* An addr_vec is placed outside any basic block. */ if (NEXT_INSN (x) && JUMP_TABLE_DATA_P (NEXT_INSN (x))) x = NEXT_INSN (x); /* But in any case, non-deletable labels can appear anywhere. */ break; default: fatal_insn ("insn outside basic block", x); } } if (JUMP_P (x) && returnjump_p (x) && ! condjump_p (x) && ! (next_nonnote_insn (x) && BARRIER_P (next_nonnote_insn (x)))) fatal_insn ("return not followed by barrier", x); if (curr_bb && x == BB_END (curr_bb)) curr_bb = NULL; } if (num_bb_notes != n_basic_blocks - NUM_FIXED_BLOCKS) internal_error ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)", num_bb_notes, n_basic_blocks); return err; } /* Assume that the preceding pass has possibly eliminated jump instructions or converted the unconditional jumps. Eliminate the edges from CFG. Return true if any edges are eliminated. */ bool purge_dead_edges (basic_block bb) { edge e; rtx insn = BB_END (bb), note; bool purged = false; bool found; edge_iterator ei; if (DEBUG_INSN_P (insn) && insn != BB_HEAD (bb)) do insn = PREV_INSN (insn); while ((DEBUG_INSN_P (insn) || NOTE_P (insn)) && insn != BB_HEAD (bb)); /* If this instruction cannot trap, remove REG_EH_REGION notes. */ if (NONJUMP_INSN_P (insn) && (note = find_reg_note (insn, REG_EH_REGION, NULL))) { rtx eqnote; if (! may_trap_p (PATTERN (insn)) || ((eqnote = find_reg_equal_equiv_note (insn)) && ! may_trap_p (XEXP (eqnote, 0)))) remove_note (insn, note); } /* Cleanup abnormal edges caused by exceptions or non-local gotos. */ for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) { bool remove = false; /* There are three types of edges we need to handle correctly here: EH edges, abnormal call EH edges, and abnormal call non-EH edges. The latter can appear when nonlocal gotos are used. */ if (e->flags & EDGE_ABNORMAL_CALL) { if (!CALL_P (insn)) remove = true; else if (can_nonlocal_goto (insn)) ; else if ((e->flags & EDGE_EH) && can_throw_internal (insn)) ; else remove = true; } else if (e->flags & EDGE_EH) remove = !can_throw_internal (insn); if (remove) { remove_edge (e); df_set_bb_dirty (bb); purged = true; } else ei_next (&ei); } if (JUMP_P (insn)) { rtx note; edge b,f; edge_iterator ei; /* We do care only about conditional jumps and simplejumps. */ if (!any_condjump_p (insn) && !returnjump_p (insn) && !simplejump_p (insn)) return purged; /* Branch probability/prediction notes are defined only for condjumps. We've possibly turned condjump into simplejump. */ if (simplejump_p (insn)) { note = find_reg_note (insn, REG_BR_PROB, NULL); if (note) remove_note (insn, note); while ((note = find_reg_note (insn, REG_BR_PRED, NULL))) remove_note (insn, note); } for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) { /* Avoid abnormal flags to leak from computed jumps turned into simplejumps. */ e->flags &= ~EDGE_ABNORMAL; /* See if this edge is one we should keep. */ if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn)) /* A conditional jump can fall through into the next block, so we should keep the edge. */ { ei_next (&ei); continue; } else if (e->dest != EXIT_BLOCK_PTR && BB_HEAD (e->dest) == JUMP_LABEL (insn)) /* If the destination block is the target of the jump, keep the edge. */ { ei_next (&ei); continue; } else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn)) /* If the destination block is the exit block, and this instruction is a return, then keep the edge. */ { ei_next (&ei); continue; } else if ((e->flags & EDGE_EH) && can_throw_internal (insn)) /* Keep the edges that correspond to exceptions thrown by this instruction and rematerialize the EDGE_ABNORMAL flag we just cleared above. */ { e->flags |= EDGE_ABNORMAL; ei_next (&ei); continue; } /* We do not need this edge. */ df_set_bb_dirty (bb); purged = true; remove_edge (e); } if (EDGE_COUNT (bb->succs) == 0 || !purged) return purged; if (dump_file) fprintf (dump_file, "Purged edges from bb %i\n", bb->index); if (!optimize) return purged; /* Redistribute probabilities. */ if (single_succ_p (bb)) { single_succ_edge (bb)->probability = REG_BR_PROB_BASE; single_succ_edge (bb)->count = bb->count; } else { note = find_reg_note (insn, REG_BR_PROB, NULL); if (!note) return purged; b = BRANCH_EDGE (bb); f = FALLTHRU_EDGE (bb); b->probability = INTVAL (XEXP (note, 0)); f->probability = REG_BR_PROB_BASE - b->probability; b->count = bb->count * b->probability / REG_BR_PROB_BASE; f->count = bb->count * f->probability / REG_BR_PROB_BASE; } return purged; } else if (CALL_P (insn) && SIBLING_CALL_P (insn)) { /* First, there should not be any EH or ABCALL edges resulting from non-local gotos and the like. If there were, we shouldn't have created the sibcall in the first place. Second, there should of course never have been a fallthru edge. */ gcc_assert (single_succ_p (bb)); gcc_assert (single_succ_edge (bb)->flags == (EDGE_SIBCALL | EDGE_ABNORMAL)); return 0; } /* If we don't see a jump insn, we don't know exactly why the block would have been broken at this point. Look for a simple, non-fallthru edge, as these are only created by conditional branches. If we find such an edge we know that there used to be a jump here and can then safely remove all non-fallthru edges. */ found = false; FOR_EACH_EDGE (e, ei, bb->succs) if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))) { found = true; break; } if (!found) return purged; /* Remove all but the fake and fallthru edges. The fake edge may be the only successor for this block in the case of noreturn calls. */ for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) { if (!(e->flags & (EDGE_FALLTHRU | EDGE_FAKE))) { df_set_bb_dirty (bb); remove_edge (e); purged = true; } else ei_next (&ei); } gcc_assert (single_succ_p (bb)); single_succ_edge (bb)->probability = REG_BR_PROB_BASE; single_succ_edge (bb)->count = bb->count; if (dump_file) fprintf (dump_file, "Purged non-fallthru edges from bb %i\n", bb->index); return purged; } /* Search all basic blocks for potentially dead edges and purge them. Return true if some edge has been eliminated. */ bool purge_all_dead_edges (void) { int purged = false; basic_block bb; FOR_EACH_BB (bb) { bool purged_here = purge_dead_edges (bb); purged |= purged_here; } return purged; } /* Same as split_block but update cfg_layout structures. */ static basic_block cfg_layout_split_block (basic_block bb, void *insnp) { rtx insn = (rtx) insnp; basic_block new_bb = rtl_split_block (bb, insn); new_bb->il.rtl->footer = bb->il.rtl->footer; bb->il.rtl->footer = NULL; return new_bb; } /* Redirect Edge to DEST. */ static edge cfg_layout_redirect_edge_and_branch (edge e, basic_block dest) { basic_block src = e->src; edge ret; if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH)) return NULL; if (e->dest == dest) return e; if (e->src != ENTRY_BLOCK_PTR && (ret = try_redirect_by_replacing_jump (e, dest, true))) { df_set_bb_dirty (src); return ret; } if (e->src == ENTRY_BLOCK_PTR && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX)) { if (dump_file) fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n", e->src->index, dest->index); df_set_bb_dirty (e->src); redirect_edge_succ (e, dest); return e; } /* Redirect_edge_and_branch may decide to turn branch into fallthru edge in the case the basic block appears to be in sequence. Avoid this transformation. */ if (e->flags & EDGE_FALLTHRU) { /* Redirect any branch edges unified with the fallthru one. */ if (JUMP_P (BB_END (src)) && label_is_jump_target_p (BB_HEAD (e->dest), BB_END (src))) { edge redirected; if (dump_file) fprintf (dump_file, "Fallthru edge unified with branch " "%i->%i redirected to %i\n", e->src->index, e->dest->index, dest->index); e->flags &= ~EDGE_FALLTHRU; redirected = redirect_branch_edge (e, dest); gcc_assert (redirected); e->flags |= EDGE_FALLTHRU; df_set_bb_dirty (e->src); return e; } /* In case we are redirecting fallthru edge to the branch edge of conditional jump, remove it. */ if (EDGE_COUNT (src->succs) == 2) { /* Find the edge that is different from E. */ edge s = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e); if (s->dest == dest && any_condjump_p (BB_END (src)) && onlyjump_p (BB_END (src))) delete_insn (BB_END (src)); } ret = redirect_edge_succ_nodup (e, dest); if (dump_file) fprintf (dump_file, "Fallthru edge %i->%i redirected to %i\n", e->src->index, e->dest->index, dest->index); } else ret = redirect_branch_edge (e, dest); /* We don't want simplejumps in the insn stream during cfglayout. */ gcc_assert (!simplejump_p (BB_END (src))); df_set_bb_dirty (src); return ret; } /* Simple wrapper as we always can redirect fallthru edges. */ static basic_block cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest) { edge redirected = cfg_layout_redirect_edge_and_branch (e, dest); gcc_assert (redirected); return NULL; } /* Same as delete_basic_block but update cfg_layout structures. */ static void cfg_layout_delete_block (basic_block bb) { rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints; if (bb->il.rtl->header) { next = BB_HEAD (bb); if (prev) NEXT_INSN (prev) = bb->il.rtl->header; else set_first_insn (bb->il.rtl->header); PREV_INSN (bb->il.rtl->header) = prev; insn = bb->il.rtl->header; while (NEXT_INSN (insn)) insn = NEXT_INSN (insn); NEXT_INSN (insn) = next; PREV_INSN (next) = insn; } next = NEXT_INSN (BB_END (bb)); if (bb->il.rtl->footer) { insn = bb->il.rtl->footer; while (insn) { if (BARRIER_P (insn)) { if (PREV_INSN (insn)) NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn); else bb->il.rtl->footer = NEXT_INSN (insn); if (NEXT_INSN (insn)) PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn); } if (LABEL_P (insn)) break; insn = NEXT_INSN (insn); } if (bb->il.rtl->footer) { insn = BB_END (bb); NEXT_INSN (insn) = bb->il.rtl->footer; PREV_INSN (bb->il.rtl->footer) = insn; while (NEXT_INSN (insn)) insn = NEXT_INSN (insn); NEXT_INSN (insn) = next; if (next) PREV_INSN (next) = insn; else set_last_insn (insn); } } if (bb->next_bb != EXIT_BLOCK_PTR) to = &bb->next_bb->il.rtl->header; else to = &cfg_layout_function_footer; rtl_delete_block (bb); if (prev) prev = NEXT_INSN (prev); else prev = get_insns (); if (next) next = PREV_INSN (next); else next = get_last_insn (); if (next && NEXT_INSN (next) != prev) { remaints = unlink_insn_chain (prev, next); insn = remaints; while (NEXT_INSN (insn)) insn = NEXT_INSN (insn); NEXT_INSN (insn) = *to; if (*to) PREV_INSN (*to) = insn; *to = remaints; } } /* Return true when blocks A and B can be safely merged. */ static bool cfg_layout_can_merge_blocks_p (basic_block a, basic_block b) { /* If we are partitioning hot/cold basic blocks, we don't want to mess up unconditional or indirect jumps that cross between hot and cold sections. Basic block partitioning may result in some jumps that appear to be optimizable (or blocks that appear to be mergeable), but which really must be left untouched (they are required to make it safely across partition boundaries). See the comments at the top of bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ if (BB_PARTITION (a) != BB_PARTITION (b)) return false; /* There must be exactly one edge in between the blocks. */ return (single_succ_p (a) && single_succ (a) == b && single_pred_p (b) == 1 && a != b /* Must be simple edge. */ && !(single_succ_edge (a)->flags & EDGE_COMPLEX) && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR /* If the jump insn has side effects, we can't kill the edge. When not optimizing, try_redirect_by_replacing_jump will not allow us to redirect an edge by replacing a table jump. */ && (!JUMP_P (BB_END (a)) || ((!optimize || reload_completed) ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a))))); } /* Merge block A and B. The blocks must be mergeable. */ static void cfg_layout_merge_blocks (basic_block a, basic_block b) { #ifdef ENABLE_CHECKING gcc_assert (cfg_layout_can_merge_blocks_p (a, b)); #endif if (dump_file) fprintf (dump_file, "merging block %d into block %d\n", b->index, a->index); /* If there was a CODE_LABEL beginning B, delete it. */ if (LABEL_P (BB_HEAD (b))) { delete_insn (BB_HEAD (b)); } /* We should have fallthru edge in a, or we can do dummy redirection to get it cleaned up. */ if (JUMP_P (BB_END (a))) try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true); gcc_assert (!JUMP_P (BB_END (a))); /* When not optimizing and the edge is the only place in RTL which holds some unique locus, emit a nop with that locus in between. */ if (!optimize && EDGE_SUCC (a, 0)->goto_locus) { rtx insn = BB_END (a), end = PREV_INSN (BB_HEAD (a)); int goto_locus = EDGE_SUCC (a, 0)->goto_locus; while (insn != end && (!INSN_P (insn) || INSN_LOCATOR (insn) == 0)) insn = PREV_INSN (insn); if (insn != end && locator_eq (INSN_LOCATOR (insn), goto_locus)) goto_locus = 0; else { insn = BB_HEAD (b); end = NEXT_INSN (BB_END (b)); while (insn != end && !INSN_P (insn)) insn = NEXT_INSN (insn); if (insn != end && INSN_LOCATOR (insn) != 0 && locator_eq (INSN_LOCATOR (insn), goto_locus)) goto_locus = 0; } if (goto_locus) { BB_END (a) = emit_insn_after_noloc (gen_nop (), BB_END (a), a); INSN_LOCATOR (BB_END (a)) = goto_locus; } } /* Possible line number notes should appear in between. */ if (b->il.rtl->header) { rtx first = BB_END (a), last; last = emit_insn_after_noloc (b->il.rtl->header, BB_END (a), a); delete_insn_chain (NEXT_INSN (first), last, false); b->il.rtl->header = NULL; } /* In the case basic blocks are not adjacent, move them around. */ if (NEXT_INSN (BB_END (a)) != BB_HEAD (b)) { rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b)); emit_insn_after_noloc (first, BB_END (a), a); /* Skip possible DELETED_LABEL insn. */ if (!NOTE_INSN_BASIC_BLOCK_P (first)) first = NEXT_INSN (first); gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first)); BB_HEAD (b) = NULL; /* emit_insn_after_noloc doesn't call df_insn_change_bb. We need to explicitly call. */ update_bb_for_insn_chain (NEXT_INSN (first), BB_END (b), a); delete_insn (first); } /* Otherwise just re-associate the instructions. */ else { rtx insn; update_bb_for_insn_chain (BB_HEAD (b), BB_END (b), a); insn = BB_HEAD (b); /* Skip possible DELETED_LABEL insn. */ if (!NOTE_INSN_BASIC_BLOCK_P (insn)) insn = NEXT_INSN (insn); gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn)); BB_HEAD (b) = NULL; BB_END (a) = BB_END (b); delete_insn (insn); } df_bb_delete (b->index); /* Possible tablejumps and barriers should appear after the block. */ if (b->il.rtl->footer) { if (!a->il.rtl->footer) a->il.rtl->footer = b->il.rtl->footer; else { rtx last = a->il.rtl->footer; while (NEXT_INSN (last)) last = NEXT_INSN (last); NEXT_INSN (last) = b->il.rtl->footer; PREV_INSN (b->il.rtl->footer) = last; } b->il.rtl->footer = NULL; } if (dump_file) fprintf (dump_file, "Merged blocks %d and %d.\n", a->index, b->index); } /* Split edge E. */ static basic_block cfg_layout_split_edge (edge e) { basic_block new_bb = create_basic_block (e->src != ENTRY_BLOCK_PTR ? NEXT_INSN (BB_END (e->src)) : get_insns (), NULL_RTX, e->src); if (e->dest == EXIT_BLOCK_PTR) BB_COPY_PARTITION (new_bb, e->src); else BB_COPY_PARTITION (new_bb, e->dest); make_edge (new_bb, e->dest, EDGE_FALLTHRU); redirect_edge_and_branch_force (e, new_bb); return new_bb; } /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */ static void rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED) { } /* Return 1 if BB ends with a call, possibly followed by some instructions that must stay with the call, 0 otherwise. */ static bool rtl_block_ends_with_call_p (basic_block bb) { rtx insn = BB_END (bb); while (!CALL_P (insn) && insn != BB_HEAD (bb) && (keep_with_call_p (insn) || NOTE_P (insn) || DEBUG_INSN_P (insn))) insn = PREV_INSN (insn); return (CALL_P (insn)); } /* Return 1 if BB ends with a conditional branch, 0 otherwise. */ static bool rtl_block_ends_with_condjump_p (const_basic_block bb) { return any_condjump_p (BB_END (bb)); } /* Return true if we need to add fake edge to exit. Helper function for rtl_flow_call_edges_add. */ static bool need_fake_edge_p (const_rtx insn) { if (!INSN_P (insn)) return false; if ((CALL_P (insn) && !SIBLING_CALL_P (insn) && !find_reg_note (insn, REG_NORETURN, NULL) && !(RTL_CONST_OR_PURE_CALL_P (insn)))) return true; return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS && MEM_VOLATILE_P (PATTERN (insn))) || (GET_CODE (PATTERN (insn)) == PARALLEL && asm_noperands (insn) != -1 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0))) || GET_CODE (PATTERN (insn)) == ASM_INPUT); } /* Add fake edges to the function exit for any non constant and non noreturn calls, volatile inline assembly in the bitmap of blocks specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks that were split. The goal is to expose cases in which entering a basic block does not imply that all subsequent instructions must be executed. */ static int rtl_flow_call_edges_add (sbitmap blocks) { int i; int blocks_split = 0; int last_bb = last_basic_block; bool check_last_block = false; if (n_basic_blocks == NUM_FIXED_BLOCKS) return 0; if (! blocks) check_last_block = true; else check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index); /* In the last basic block, before epilogue generation, there will be a fallthru edge to EXIT. Special care is required if the last insn of the last basic block is a call because make_edge folds duplicate edges, which would result in the fallthru edge also being marked fake, which would result in the fallthru edge being removed by remove_fake_edges, which would result in an invalid CFG. Moreover, we can't elide the outgoing fake edge, since the block profiler needs to take this into account in order to solve the minimal spanning tree in the case that the call doesn't return. Handle this by adding a dummy instruction in a new last basic block. */ if (check_last_block) { basic_block bb = EXIT_BLOCK_PTR->prev_bb; rtx insn = BB_END (bb); /* Back up past insns that must be kept in the same block as a call. */ while (insn != BB_HEAD (bb) && keep_with_call_p (insn)) insn = PREV_INSN (insn); if (need_fake_edge_p (insn)) { edge e; e = find_edge (bb, EXIT_BLOCK_PTR); if (e) { insert_insn_on_edge (gen_use (const0_rtx), e); commit_edge_insertions (); } } } /* Now add fake edges to the function exit for any non constant calls since there is no way that we can determine if they will return or not... */ for (i = NUM_FIXED_BLOCKS; i < last_bb; i++) { basic_block bb = BASIC_BLOCK (i); rtx insn; rtx prev_insn; if (!bb) continue; if (blocks && !TEST_BIT (blocks, i)) continue; for (insn = BB_END (bb); ; insn = prev_insn) { prev_insn = PREV_INSN (insn); if (need_fake_edge_p (insn)) { edge e; rtx split_at_insn = insn; /* Don't split the block between a call and an insn that should remain in the same block as the call. */ if (CALL_P (insn)) while (split_at_insn != BB_END (bb) && keep_with_call_p (NEXT_INSN (split_at_insn))) split_at_insn = NEXT_INSN (split_at_insn); /* The handling above of the final block before the epilogue should be enough to verify that there is no edge to the exit block in CFG already. Calling make_edge in such case would cause us to mark that edge as fake and remove it later. */ #ifdef ENABLE_CHECKING if (split_at_insn == BB_END (bb)) { e = find_edge (bb, EXIT_BLOCK_PTR); gcc_assert (e == NULL); } #endif /* Note that the following may create a new basic block and renumber the existing basic blocks. */ if (split_at_insn != BB_END (bb)) { e = split_block (bb, split_at_insn); if (e) blocks_split++; } make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE); } if (insn == BB_HEAD (bb)) break; } } if (blocks_split) verify_flow_info (); return blocks_split; } /* Add COMP_RTX as a condition at end of COND_BB. FIRST_HEAD is the conditional branch target, SECOND_HEAD should be the fall-thru there is no need to handle this here the loop versioning code handles this. the reason for SECON_HEAD is that it is needed for condition in trees, and this should be of the same type since it is a hook. */ static void rtl_lv_add_condition_to_bb (basic_block first_head , basic_block second_head ATTRIBUTE_UNUSED, basic_block cond_bb, void *comp_rtx) { rtx label, seq, jump; rtx op0 = XEXP ((rtx)comp_rtx, 0); rtx op1 = XEXP ((rtx)comp_rtx, 1); enum rtx_code comp = GET_CODE ((rtx)comp_rtx); enum machine_mode mode; label = block_label (first_head); mode = GET_MODE (op0); if (mode == VOIDmode) mode = GET_MODE (op1); start_sequence (); op0 = force_operand (op0, NULL_RTX); op1 = force_operand (op1, NULL_RTX); do_compare_rtx_and_jump (op0, op1, comp, 0, mode, NULL_RTX, NULL_RTX, label, -1); jump = get_last_insn (); JUMP_LABEL (jump) = label; LABEL_NUSES (label)++; seq = get_insns (); end_sequence (); /* Add the new cond , in the new head. */ emit_insn_after(seq, BB_END(cond_bb)); } /* Given a block B with unconditional branch at its end, get the store the return the branch edge and the fall-thru edge in BRANCH_EDGE and FALLTHRU_EDGE respectively. */ static void rtl_extract_cond_bb_edges (basic_block b, edge *branch_edge, edge *fallthru_edge) { edge e = EDGE_SUCC (b, 0); if (e->flags & EDGE_FALLTHRU) { *fallthru_edge = e; *branch_edge = EDGE_SUCC (b, 1); } else { *branch_edge = e; *fallthru_edge = EDGE_SUCC (b, 1); } } void init_rtl_bb_info (basic_block bb) { gcc_assert (!bb->il.rtl); bb->il.rtl = GGC_CNEW (struct rtl_bb_info); } /* Add EXPR to the end of basic block BB. */ rtx insert_insn_end_bb_new (rtx pat, basic_block bb) { rtx insn = BB_END (bb); rtx new_insn; rtx pat_end = pat; while (NEXT_INSN (pat_end) != NULL_RTX) pat_end = NEXT_INSN (pat_end); /* If the last insn is a jump, insert EXPR in front [taking care to handle cc0, etc. properly]. Similarly we need to care trapping instructions in presence of non-call exceptions. */ if (JUMP_P (insn) || (NONJUMP_INSN_P (insn) && (!single_succ_p (bb) || single_succ_edge (bb)->flags & EDGE_ABNORMAL))) { #ifdef HAVE_cc0 rtx note; #endif /* If this is a jump table, then we can't insert stuff here. Since we know the previous real insn must be the tablejump, we insert the new instruction just before the tablejump. */ if (GET_CODE (PATTERN (insn)) == ADDR_VEC || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC) insn = prev_real_insn (insn); #ifdef HAVE_cc0 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts if cc0 isn't set. */ note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX); if (note) insn = XEXP (note, 0); else { rtx maybe_cc0_setter = prev_nonnote_insn (insn); if (maybe_cc0_setter && INSN_P (maybe_cc0_setter) && sets_cc0_p (PATTERN (maybe_cc0_setter))) insn = maybe_cc0_setter; } #endif /* FIXME: What if something in cc0/jump uses value set in new insn? */ new_insn = emit_insn_before_noloc (pat, insn, bb); } /* Likewise if the last insn is a call, as will happen in the presence of exception handling. */ else if (CALL_P (insn) && (!single_succ_p (bb) || single_succ_edge (bb)->flags & EDGE_ABNORMAL)) { /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers, we search backward and place the instructions before the first parameter is loaded. Do this for everyone for consistency and a presumption that we'll get better code elsewhere as well. */ /* Since different machines initialize their parameter registers in different orders, assume nothing. Collect the set of all parameter registers. */ insn = find_first_parameter_load (insn, BB_HEAD (bb)); /* If we found all the parameter loads, then we want to insert before the first parameter load. If we did not find all the parameter loads, then we might have stopped on the head of the block, which could be a CODE_LABEL. If we inserted before the CODE_LABEL, then we would be putting the insn in the wrong basic block. In that case, put the insn after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */ while (LABEL_P (insn) || NOTE_INSN_BASIC_BLOCK_P (insn)) insn = NEXT_INSN (insn); new_insn = emit_insn_before_noloc (pat, insn, bb); } else new_insn = emit_insn_after_noloc (pat, insn, bb); return new_insn; } /* Returns true if it is possible to remove edge E by redirecting it to the destination of the other edge from E->src. */ static bool rtl_can_remove_branch_p (const_edge e) { const_basic_block src = e->src; const_basic_block target = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest; const_rtx insn = BB_END (src), set; /* The conditions are taken from try_redirect_by_replacing_jump. */ if (target == EXIT_BLOCK_PTR) return false; if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH)) return false; if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX) || BB_PARTITION (src) != BB_PARTITION (target)) return false; if (!onlyjump_p (insn) || tablejump_p (insn, NULL, NULL)) return false; set = single_set (insn); if (!set || side_effects_p (set)) return false; return true; } /* Implementation of CFG manipulation for linearized RTL. */ struct cfg_hooks rtl_cfg_hooks = { "rtl", rtl_verify_flow_info, rtl_dump_bb, rtl_create_basic_block, rtl_redirect_edge_and_branch, rtl_redirect_edge_and_branch_force, rtl_can_remove_branch_p, rtl_delete_block, rtl_split_block, rtl_move_block_after, rtl_can_merge_blocks, /* can_merge_blocks_p */ rtl_merge_blocks, rtl_predict_edge, rtl_predicted_by_p, NULL, /* can_duplicate_block_p */ NULL, /* duplicate_block */ rtl_split_edge, rtl_make_forwarder_block, rtl_tidy_fallthru_edge, rtl_block_ends_with_call_p, rtl_block_ends_with_condjump_p, rtl_flow_call_edges_add, NULL, /* execute_on_growing_pred */ NULL, /* execute_on_shrinking_pred */ NULL, /* duplicate loop for trees */ NULL, /* lv_add_condition_to_bb */ NULL, /* lv_adjust_loop_header_phi*/ NULL, /* extract_cond_bb_edges */ NULL /* flush_pending_stmts */ }; /* Implementation of CFG manipulation for cfg layout RTL, where basic block connected via fallthru edges does not have to be adjacent. This representation will hopefully become the default one in future version of the compiler. */ /* We do not want to declare these functions in a header file, since they should only be used through the cfghooks interface, and we do not want to move them here since it would require also moving quite a lot of related code. They are in cfglayout.c. */ extern bool cfg_layout_can_duplicate_bb_p (const_basic_block); extern basic_block cfg_layout_duplicate_bb (basic_block); struct cfg_hooks cfg_layout_rtl_cfg_hooks = { "cfglayout mode", rtl_verify_flow_info_1, rtl_dump_bb, cfg_layout_create_basic_block, cfg_layout_redirect_edge_and_branch, cfg_layout_redirect_edge_and_branch_force, rtl_can_remove_branch_p, cfg_layout_delete_block, cfg_layout_split_block, rtl_move_block_after, cfg_layout_can_merge_blocks_p, cfg_layout_merge_blocks, rtl_predict_edge, rtl_predicted_by_p, cfg_layout_can_duplicate_bb_p, cfg_layout_duplicate_bb, cfg_layout_split_edge, rtl_make_forwarder_block, NULL, rtl_block_ends_with_call_p, rtl_block_ends_with_condjump_p, rtl_flow_call_edges_add, NULL, /* execute_on_growing_pred */ NULL, /* execute_on_shrinking_pred */ duplicate_loop_to_header_edge, /* duplicate loop for trees */ rtl_lv_add_condition_to_bb, /* lv_add_condition_to_bb */ NULL, /* lv_adjust_loop_header_phi*/ rtl_extract_cond_bb_edges, /* extract_cond_bb_edges */ NULL /* flush_pending_stmts */ };