| /* Perform instruction reorganizations for delay slot filling. |
| Copyright (C) 1992-2017 Free Software Foundation, Inc. |
| Contributed by Richard Kenner (kenner@vlsi1.ultra.nyu.edu). |
| Hacked by Michael Tiemann (tiemann@cygnus.com). |
| |
| 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/>. */ |
| |
| /* Instruction reorganization pass. |
| |
| This pass runs after register allocation and final jump |
| optimization. It should be the last pass to run before peephole. |
| It serves primarily to fill delay slots of insns, typically branch |
| and call insns. Other insns typically involve more complicated |
| interactions of data dependencies and resource constraints, and |
| are better handled by scheduling before register allocation (by the |
| function `schedule_insns'). |
| |
| The Branch Penalty is the number of extra cycles that are needed to |
| execute a branch insn. On an ideal machine, branches take a single |
| cycle, and the Branch Penalty is 0. Several RISC machines approach |
| branch delays differently: |
| |
| The MIPS has a single branch delay slot. Most insns |
| (except other branches) can be used to fill this slot. When the |
| slot is filled, two insns execute in two cycles, reducing the |
| branch penalty to zero. |
| |
| The SPARC always has a branch delay slot, but its effects can be |
| annulled when the branch is not taken. This means that failing to |
| find other sources of insns, we can hoist an insn from the branch |
| target that would only be safe to execute knowing that the branch |
| is taken. |
| |
| The HP-PA always has a branch delay slot. For unconditional branches |
| its effects can be annulled when the branch is taken. The effects |
| of the delay slot in a conditional branch can be nullified for forward |
| taken branches, or for untaken backward branches. This means |
| we can hoist insns from the fall-through path for forward branches or |
| steal insns from the target of backward branches. |
| |
| The TMS320C3x and C4x have three branch delay slots. When the three |
| slots are filled, the branch penalty is zero. Most insns can fill the |
| delay slots except jump insns. |
| |
| Three techniques for filling delay slots have been implemented so far: |
| |
| (1) `fill_simple_delay_slots' is the simplest, most efficient way |
| to fill delay slots. This pass first looks for insns which come |
| from before the branch and which are safe to execute after the |
| branch. Then it searches after the insn requiring delay slots or, |
| in the case of a branch, for insns that are after the point at |
| which the branch merges into the fallthrough code, if such a point |
| exists. When such insns are found, the branch penalty decreases |
| and no code expansion takes place. |
| |
| (2) `fill_eager_delay_slots' is more complicated: it is used for |
| scheduling conditional jumps, or for scheduling jumps which cannot |
| be filled using (1). A machine need not have annulled jumps to use |
| this strategy, but it helps (by keeping more options open). |
| `fill_eager_delay_slots' tries to guess the direction the branch |
| will go; if it guesses right 100% of the time, it can reduce the |
| branch penalty as much as `fill_simple_delay_slots' does. If it |
| guesses wrong 100% of the time, it might as well schedule nops. When |
| `fill_eager_delay_slots' takes insns from the fall-through path of |
| the jump, usually there is no code expansion; when it takes insns |
| from the branch target, there is code expansion if it is not the |
| only way to reach that target. |
| |
| (3) `relax_delay_slots' uses a set of rules to simplify code that |
| has been reorganized by (1) and (2). It finds cases where |
| conditional test can be eliminated, jumps can be threaded, extra |
| insns can be eliminated, etc. It is the job of (1) and (2) to do a |
| good job of scheduling locally; `relax_delay_slots' takes care of |
| making the various individual schedules work well together. It is |
| especially tuned to handle the control flow interactions of branch |
| insns. It does nothing for insns with delay slots that do not |
| branch. |
| |
| On machines that use CC0, we are very conservative. We will not make |
| a copy of an insn involving CC0 since we want to maintain a 1-1 |
| correspondence between the insn that sets and uses CC0. The insns are |
| allowed to be separated by placing an insn that sets CC0 (but not an insn |
| that uses CC0; we could do this, but it doesn't seem worthwhile) in a |
| delay slot. In that case, we point each insn at the other with REG_CC_USER |
| and REG_CC_SETTER notes. Note that these restrictions affect very few |
| machines because most RISC machines with delay slots will not use CC0 |
| (the RT is the only known exception at this point). */ |
| |
| #include "config.h" |
| #include "system.h" |
| #include "coretypes.h" |
| #include "backend.h" |
| #include "target.h" |
| #include "rtl.h" |
| #include "tree.h" |
| #include "predict.h" |
| #include "memmodel.h" |
| #include "tm_p.h" |
| #include "expmed.h" |
| #include "insn-config.h" |
| #include "emit-rtl.h" |
| #include "recog.h" |
| #include "insn-attr.h" |
| #include "resource.h" |
| #include "params.h" |
| #include "tree-pass.h" |
| |
| |
| /* First, some functions that were used before GCC got a control flow graph. |
| These functions are now only used here in reorg.c, and have therefore |
| been moved here to avoid inadvertent misuse elsewhere in the compiler. */ |
| |
| /* Return the last label to mark the same position as LABEL. Return LABEL |
| itself if it is null or any return rtx. */ |
| |
| static rtx |
| skip_consecutive_labels (rtx label_or_return) |
| { |
| rtx_insn *insn; |
| |
| if (label_or_return && ANY_RETURN_P (label_or_return)) |
| return label_or_return; |
| |
| rtx_insn *label = as_a <rtx_insn *> (label_or_return); |
| |
| for (insn = label; insn != 0 && !INSN_P (insn); insn = NEXT_INSN (insn)) |
| if (LABEL_P (insn)) |
| label = insn; |
| |
| return label; |
| } |
| |
| /* INSN uses CC0 and is being moved into a delay slot. Set up REG_CC_SETTER |
| and REG_CC_USER notes so we can find it. */ |
| |
| static void |
| link_cc0_insns (rtx_insn *insn) |
| { |
| rtx user = next_nonnote_insn (insn); |
| |
| if (NONJUMP_INSN_P (user) && GET_CODE (PATTERN (user)) == SEQUENCE) |
| user = XVECEXP (PATTERN (user), 0, 0); |
| |
| add_reg_note (user, REG_CC_SETTER, insn); |
| add_reg_note (insn, REG_CC_USER, user); |
| } |
| |
| /* Insns which have delay slots that have not yet been filled. */ |
| |
| static struct obstack unfilled_slots_obstack; |
| static rtx *unfilled_firstobj; |
| |
| /* Define macros to refer to the first and last slot containing unfilled |
| insns. These are used because the list may move and its address |
| should be recomputed at each use. */ |
| |
| #define unfilled_slots_base \ |
| ((rtx_insn **) obstack_base (&unfilled_slots_obstack)) |
| |
| #define unfilled_slots_next \ |
| ((rtx_insn **) obstack_next_free (&unfilled_slots_obstack)) |
| |
| /* Points to the label before the end of the function, or before a |
| return insn. */ |
| static rtx_code_label *function_return_label; |
| /* Likewise for a simple_return. */ |
| static rtx_code_label *function_simple_return_label; |
| |
| /* Mapping between INSN_UID's and position in the code since INSN_UID's do |
| not always monotonically increase. */ |
| static int *uid_to_ruid; |
| |
| /* Highest valid index in `uid_to_ruid'. */ |
| static int max_uid; |
| |
| static int stop_search_p (rtx_insn *, int); |
| static int resource_conflicts_p (struct resources *, struct resources *); |
| static int insn_references_resource_p (rtx, struct resources *, bool); |
| static int insn_sets_resource_p (rtx, struct resources *, bool); |
| static rtx_code_label *find_end_label (rtx); |
| static rtx_insn *emit_delay_sequence (rtx_insn *, const vec<rtx_insn *> &, |
| int); |
| static void add_to_delay_list (rtx_insn *, vec<rtx_insn *> *); |
| static rtx_insn *delete_from_delay_slot (rtx_insn *); |
| static void delete_scheduled_jump (rtx_insn *); |
| static void note_delay_statistics (int, int); |
| static int get_jump_flags (const rtx_insn *, rtx); |
| static int mostly_true_jump (rtx); |
| static rtx get_branch_condition (const rtx_insn *, rtx); |
| static int condition_dominates_p (rtx, const rtx_insn *); |
| static int redirect_with_delay_slots_safe_p (rtx_insn *, rtx, rtx); |
| static int redirect_with_delay_list_safe_p (rtx_insn *, rtx, |
| const vec<rtx_insn *> &); |
| static int check_annul_list_true_false (int, const vec<rtx_insn *> &); |
| static void steal_delay_list_from_target (rtx_insn *, rtx, rtx_sequence *, |
| vec<rtx_insn *> *, |
| struct resources *, |
| struct resources *, |
| struct resources *, |
| int, int *, int *, |
| rtx *); |
| static void steal_delay_list_from_fallthrough (rtx_insn *, rtx, rtx_sequence *, |
| vec<rtx_insn *> *, |
| struct resources *, |
| struct resources *, |
| struct resources *, |
| int, int *, int *); |
| static void try_merge_delay_insns (rtx_insn *, rtx_insn *); |
| static rtx_insn *redundant_insn (rtx, rtx_insn *, const vec<rtx_insn *> &); |
| static int own_thread_p (rtx, rtx, int); |
| static void update_block (rtx_insn *, rtx_insn *); |
| static int reorg_redirect_jump (rtx_jump_insn *, rtx); |
| static void update_reg_dead_notes (rtx_insn *, rtx_insn *); |
| static void fix_reg_dead_note (rtx_insn *, rtx); |
| static void update_reg_unused_notes (rtx_insn *, rtx); |
| static void fill_simple_delay_slots (int); |
| static void fill_slots_from_thread (rtx_jump_insn *, rtx, rtx, rtx, |
| int, int, int, int, |
| int *, vec<rtx_insn *> *); |
| static void fill_eager_delay_slots (void); |
| static void relax_delay_slots (rtx_insn *); |
| static void make_return_insns (rtx_insn *); |
| |
| /* A wrapper around next_active_insn which takes care to return ret_rtx |
| unchanged. */ |
| |
| static rtx |
| first_active_target_insn (rtx insn) |
| { |
| if (ANY_RETURN_P (insn)) |
| return insn; |
| return next_active_insn (as_a <rtx_insn *> (insn)); |
| } |
| |
| /* Return true iff INSN is a simplejump, or any kind of return insn. */ |
| |
| static bool |
| simplejump_or_return_p (rtx insn) |
| { |
| return (JUMP_P (insn) |
| && (simplejump_p (as_a <rtx_insn *> (insn)) |
| || ANY_RETURN_P (PATTERN (insn)))); |
| } |
| |
| /* Return TRUE if this insn should stop the search for insn to fill delay |
| slots. LABELS_P indicates that labels should terminate the search. |
| In all cases, jumps terminate the search. */ |
| |
| static int |
| stop_search_p (rtx_insn *insn, int labels_p) |
| { |
| if (insn == 0) |
| return 1; |
| |
| /* If the insn can throw an exception that is caught within the function, |
| it may effectively perform a jump from the viewpoint of the function. |
| Therefore act like for a jump. */ |
| if (can_throw_internal (insn)) |
| return 1; |
| |
| switch (GET_CODE (insn)) |
| { |
| case NOTE: |
| case CALL_INSN: |
| return 0; |
| |
| case CODE_LABEL: |
| return labels_p; |
| |
| case JUMP_INSN: |
| case BARRIER: |
| return 1; |
| |
| case INSN: |
| /* OK unless it contains a delay slot or is an `asm' insn of some type. |
| We don't know anything about these. */ |
| return (GET_CODE (PATTERN (insn)) == SEQUENCE |
| || GET_CODE (PATTERN (insn)) == ASM_INPUT |
| || asm_noperands (PATTERN (insn)) >= 0); |
| |
| default: |
| gcc_unreachable (); |
| } |
| } |
| |
| /* Return TRUE if any resources are marked in both RES1 and RES2 or if either |
| resource set contains a volatile memory reference. Otherwise, return FALSE. */ |
| |
| static int |
| resource_conflicts_p (struct resources *res1, struct resources *res2) |
| { |
| if ((res1->cc && res2->cc) || (res1->memory && res2->memory) |
| || res1->volatil || res2->volatil) |
| return 1; |
| |
| return hard_reg_set_intersect_p (res1->regs, res2->regs); |
| } |
| |
| /* Return TRUE if any resource marked in RES, a `struct resources', is |
| referenced by INSN. If INCLUDE_DELAYED_EFFECTS is set, return if the called |
| routine is using those resources. |
| |
| We compute this by computing all the resources referenced by INSN and |
| seeing if this conflicts with RES. It might be faster to directly check |
| ourselves, and this is the way it used to work, but it means duplicating |
| a large block of complex code. */ |
| |
| static int |
| insn_references_resource_p (rtx insn, struct resources *res, |
| bool include_delayed_effects) |
| { |
| struct resources insn_res; |
| |
| CLEAR_RESOURCE (&insn_res); |
| mark_referenced_resources (insn, &insn_res, include_delayed_effects); |
| return resource_conflicts_p (&insn_res, res); |
| } |
| |
| /* Return TRUE if INSN modifies resources that are marked in RES. |
| INCLUDE_DELAYED_EFFECTS is set if the actions of that routine should be |
| included. CC0 is only modified if it is explicitly set; see comments |
| in front of mark_set_resources for details. */ |
| |
| static int |
| insn_sets_resource_p (rtx insn, struct resources *res, |
| bool include_delayed_effects) |
| { |
| struct resources insn_sets; |
| |
| CLEAR_RESOURCE (&insn_sets); |
| mark_set_resources (insn, &insn_sets, 0, |
| (include_delayed_effects |
| ? MARK_SRC_DEST_CALL |
| : MARK_SRC_DEST)); |
| return resource_conflicts_p (&insn_sets, res); |
| } |
| |
| /* Find a label at the end of the function or before a RETURN. If there |
| is none, try to make one. If that fails, returns 0. |
| |
| The property of such a label is that it is placed just before the |
| epilogue or a bare RETURN insn, so that another bare RETURN can be |
| turned into a jump to the label unconditionally. In particular, the |
| label cannot be placed before a RETURN insn with a filled delay slot. |
| |
| ??? There may be a problem with the current implementation. Suppose |
| we start with a bare RETURN insn and call find_end_label. It may set |
| function_return_label just before the RETURN. Suppose the machinery |
| is able to fill the delay slot of the RETURN insn afterwards. Then |
| function_return_label is no longer valid according to the property |
| described above and find_end_label will still return it unmodified. |
| Note that this is probably mitigated by the following observation: |
| once function_return_label is made, it is very likely the target of |
| a jump, so filling the delay slot of the RETURN will be much more |
| difficult. |
| KIND is either simple_return_rtx or ret_rtx, indicating which type of |
| return we're looking for. */ |
| |
| static rtx_code_label * |
| find_end_label (rtx kind) |
| { |
| rtx_insn *insn; |
| rtx_code_label **plabel; |
| |
| if (kind == ret_rtx) |
| plabel = &function_return_label; |
| else |
| { |
| gcc_assert (kind == simple_return_rtx); |
| plabel = &function_simple_return_label; |
| } |
| |
| /* If we found one previously, return it. */ |
| if (*plabel) |
| return *plabel; |
| |
| /* Otherwise, see if there is a label at the end of the function. If there |
| is, it must be that RETURN insns aren't needed, so that is our return |
| label and we don't have to do anything else. */ |
| |
| insn = get_last_insn (); |
| while (NOTE_P (insn) |
| || (NONJUMP_INSN_P (insn) |
| && (GET_CODE (PATTERN (insn)) == USE |
| || GET_CODE (PATTERN (insn)) == CLOBBER))) |
| insn = PREV_INSN (insn); |
| |
| /* When a target threads its epilogue we might already have a |
| suitable return insn. If so put a label before it for the |
| function_return_label. */ |
| if (BARRIER_P (insn) |
| && JUMP_P (PREV_INSN (insn)) |
| && PATTERN (PREV_INSN (insn)) == kind) |
| { |
| rtx_insn *temp = PREV_INSN (PREV_INSN (insn)); |
| rtx_code_label *label = gen_label_rtx (); |
| LABEL_NUSES (label) = 0; |
| |
| /* Put the label before any USE insns that may precede the RETURN |
| insn. */ |
| while (GET_CODE (temp) == USE) |
| temp = PREV_INSN (temp); |
| |
| emit_label_after (label, temp); |
| *plabel = label; |
| } |
| |
| else if (LABEL_P (insn)) |
| *plabel = as_a <rtx_code_label *> (insn); |
| else |
| { |
| rtx_code_label *label = gen_label_rtx (); |
| LABEL_NUSES (label) = 0; |
| /* If the basic block reorder pass moves the return insn to |
| some other place try to locate it again and put our |
| function_return_label there. */ |
| while (insn && ! (JUMP_P (insn) && (PATTERN (insn) == kind))) |
| insn = PREV_INSN (insn); |
| if (insn) |
| { |
| insn = PREV_INSN (insn); |
| |
| /* Put the label before any USE insns that may precede the |
| RETURN insn. */ |
| while (GET_CODE (insn) == USE) |
| insn = PREV_INSN (insn); |
| |
| emit_label_after (label, insn); |
| } |
| else |
| { |
| if (targetm.have_epilogue () && ! targetm.have_return ()) |
| /* The RETURN insn has its delay slot filled so we cannot |
| emit the label just before it. Since we already have |
| an epilogue and cannot emit a new RETURN, we cannot |
| emit the label at all. */ |
| return NULL; |
| |
| /* Otherwise, make a new label and emit a RETURN and BARRIER, |
| if needed. */ |
| emit_label (label); |
| if (targetm.have_return ()) |
| { |
| /* The return we make may have delay slots too. */ |
| rtx_insn *pat = targetm.gen_return (); |
| rtx_insn *insn = emit_jump_insn (pat); |
| set_return_jump_label (insn); |
| emit_barrier (); |
| if (num_delay_slots (insn) > 0) |
| obstack_ptr_grow (&unfilled_slots_obstack, insn); |
| } |
| } |
| *plabel = label; |
| } |
| |
| /* Show one additional use for this label so it won't go away until |
| we are done. */ |
| ++LABEL_NUSES (*plabel); |
| |
| return *plabel; |
| } |
| |
| /* Put INSN and LIST together in a SEQUENCE rtx of LENGTH, and replace |
| the pattern of INSN with the SEQUENCE. |
| |
| Returns the insn containing the SEQUENCE that replaces INSN. */ |
| |
| static rtx_insn * |
| emit_delay_sequence (rtx_insn *insn, const vec<rtx_insn *> &list, int length) |
| { |
| /* Allocate the rtvec to hold the insns and the SEQUENCE. */ |
| rtvec seqv = rtvec_alloc (length + 1); |
| rtx seq = gen_rtx_SEQUENCE (VOIDmode, seqv); |
| rtx_insn *seq_insn = make_insn_raw (seq); |
| |
| /* If DELAY_INSN has a location, use it for SEQ_INSN. If DELAY_INSN does |
| not have a location, but one of the delayed insns does, we pick up a |
| location from there later. */ |
| INSN_LOCATION (seq_insn) = INSN_LOCATION (insn); |
| |
| /* Unlink INSN from the insn chain, so that we can put it into |
| the SEQUENCE. Remember where we want to emit SEQUENCE in AFTER. */ |
| rtx_insn *after = PREV_INSN (insn); |
| remove_insn (insn); |
| SET_NEXT_INSN (insn) = SET_PREV_INSN (insn) = NULL; |
| |
| /* Build our SEQUENCE and rebuild the insn chain. */ |
| start_sequence (); |
| XVECEXP (seq, 0, 0) = emit_insn (insn); |
| |
| unsigned int delay_insns = list.length (); |
| gcc_assert (delay_insns == (unsigned int) length); |
| for (unsigned int i = 0; i < delay_insns; i++) |
| { |
| rtx_insn *tem = list[i]; |
| rtx note, next; |
| |
| /* Show that this copy of the insn isn't deleted. */ |
| tem->set_undeleted (); |
| |
| /* Unlink insn from its original place, and re-emit it into |
| the sequence. */ |
| SET_NEXT_INSN (tem) = SET_PREV_INSN (tem) = NULL; |
| XVECEXP (seq, 0, i + 1) = emit_insn (tem); |
| |
| /* SPARC assembler, for instance, emit warning when debug info is output |
| into the delay slot. */ |
| if (INSN_LOCATION (tem) && !INSN_LOCATION (seq_insn)) |
| INSN_LOCATION (seq_insn) = INSN_LOCATION (tem); |
| INSN_LOCATION (tem) = 0; |
| |
| for (note = REG_NOTES (tem); note; note = next) |
| { |
| next = XEXP (note, 1); |
| switch (REG_NOTE_KIND (note)) |
| { |
| case REG_DEAD: |
| /* Remove any REG_DEAD notes because we can't rely on them now |
| that the insn has been moved. */ |
| remove_note (tem, note); |
| break; |
| |
| case REG_LABEL_OPERAND: |
| case REG_LABEL_TARGET: |
| /* Keep the label reference count up to date. */ |
| if (LABEL_P (XEXP (note, 0))) |
| LABEL_NUSES (XEXP (note, 0)) ++; |
| break; |
| |
| default: |
| break; |
| } |
| } |
| } |
| end_sequence (); |
| |
| /* Splice our SEQUENCE into the insn stream where INSN used to be. */ |
| add_insn_after (seq_insn, after, NULL); |
| |
| return seq_insn; |
| } |
| |
| /* Add INSN to DELAY_LIST and return the head of the new list. The list must |
| be in the order in which the insns are to be executed. */ |
| |
| static void |
| add_to_delay_list (rtx_insn *insn, vec<rtx_insn *> *delay_list) |
| { |
| /* If INSN has its block number recorded, clear it since we may |
| be moving the insn to a new block. */ |
| clear_hashed_info_for_insn (insn); |
| delay_list->safe_push (insn); |
| } |
| |
| /* Delete INSN from the delay slot of the insn that it is in, which may |
| produce an insn with no delay slots. Return the new insn. */ |
| |
| static rtx_insn * |
| delete_from_delay_slot (rtx_insn *insn) |
| { |
| rtx_insn *trial, *seq_insn, *prev; |
| rtx_sequence *seq; |
| int i; |
| int had_barrier = 0; |
| |
| /* We first must find the insn containing the SEQUENCE with INSN in its |
| delay slot. Do this by finding an insn, TRIAL, where |
| PREV_INSN (NEXT_INSN (TRIAL)) != TRIAL. */ |
| |
| for (trial = insn; |
| PREV_INSN (NEXT_INSN (trial)) == trial; |
| trial = NEXT_INSN (trial)) |
| ; |
| |
| seq_insn = PREV_INSN (NEXT_INSN (trial)); |
| seq = as_a <rtx_sequence *> (PATTERN (seq_insn)); |
| |
| if (NEXT_INSN (seq_insn) && BARRIER_P (NEXT_INSN (seq_insn))) |
| had_barrier = 1; |
| |
| /* Create a delay list consisting of all the insns other than the one |
| we are deleting (unless we were the only one). */ |
| auto_vec<rtx_insn *, 5> delay_list; |
| if (seq->len () > 2) |
| for (i = 1; i < seq->len (); i++) |
| if (seq->insn (i) != insn) |
| add_to_delay_list (seq->insn (i), &delay_list); |
| |
| /* Delete the old SEQUENCE, re-emit the insn that used to have the delay |
| list, and rebuild the delay list if non-empty. */ |
| prev = PREV_INSN (seq_insn); |
| trial = seq->insn (0); |
| delete_related_insns (seq_insn); |
| add_insn_after (trial, prev, NULL); |
| |
| /* If there was a barrier after the old SEQUENCE, remit it. */ |
| if (had_barrier) |
| emit_barrier_after (trial); |
| |
| /* If there are any delay insns, remit them. Otherwise clear the |
| annul flag. */ |
| if (!delay_list.is_empty ()) |
| trial = emit_delay_sequence (trial, delay_list, XVECLEN (seq, 0) - 2); |
| else if (JUMP_P (trial)) |
| INSN_ANNULLED_BRANCH_P (trial) = 0; |
| |
| INSN_FROM_TARGET_P (insn) = 0; |
| |
| /* Show we need to fill this insn again. */ |
| obstack_ptr_grow (&unfilled_slots_obstack, trial); |
| |
| return trial; |
| } |
| |
| /* Delete INSN, a JUMP_INSN. If it is a conditional jump, we must track down |
| the insn that sets CC0 for it and delete it too. */ |
| |
| static void |
| delete_scheduled_jump (rtx_insn *insn) |
| { |
| /* Delete the insn that sets cc0 for us. On machines without cc0, we could |
| delete the insn that sets the condition code, but it is hard to find it. |
| Since this case is rare anyway, don't bother trying; there would likely |
| be other insns that became dead anyway, which we wouldn't know to |
| delete. */ |
| |
| if (HAVE_cc0 && reg_mentioned_p (cc0_rtx, insn)) |
| { |
| rtx note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX); |
| |
| /* If a reg-note was found, it points to an insn to set CC0. This |
| insn is in the delay list of some other insn. So delete it from |
| the delay list it was in. */ |
| if (note) |
| { |
| if (! FIND_REG_INC_NOTE (XEXP (note, 0), NULL_RTX) |
| && sets_cc0_p (PATTERN (XEXP (note, 0))) == 1) |
| delete_from_delay_slot (as_a <rtx_insn *> (XEXP (note, 0))); |
| } |
| else |
| { |
| /* The insn setting CC0 is our previous insn, but it may be in |
| a delay slot. It will be the last insn in the delay slot, if |
| it is. */ |
| rtx_insn *trial = previous_insn (insn); |
| if (NOTE_P (trial)) |
| trial = prev_nonnote_insn (trial); |
| if (sets_cc0_p (PATTERN (trial)) != 1 |
| || FIND_REG_INC_NOTE (trial, NULL_RTX)) |
| return; |
| if (PREV_INSN (NEXT_INSN (trial)) == trial) |
| delete_related_insns (trial); |
| else |
| delete_from_delay_slot (trial); |
| } |
| } |
| |
| delete_related_insns (insn); |
| } |
| |
| /* Counters for delay-slot filling. */ |
| |
| #define NUM_REORG_FUNCTIONS 2 |
| #define MAX_DELAY_HISTOGRAM 3 |
| #define MAX_REORG_PASSES 2 |
| |
| static int num_insns_needing_delays[NUM_REORG_FUNCTIONS][MAX_REORG_PASSES]; |
| |
| static int num_filled_delays[NUM_REORG_FUNCTIONS][MAX_DELAY_HISTOGRAM+1][MAX_REORG_PASSES]; |
| |
| static int reorg_pass_number; |
| |
| static void |
| note_delay_statistics (int slots_filled, int index) |
| { |
| num_insns_needing_delays[index][reorg_pass_number]++; |
| if (slots_filled > MAX_DELAY_HISTOGRAM) |
| slots_filled = MAX_DELAY_HISTOGRAM; |
| num_filled_delays[index][slots_filled][reorg_pass_number]++; |
| } |
| |
| /* Optimize the following cases: |
| |
| 1. When a conditional branch skips over only one instruction, |
| use an annulling branch and put that insn in the delay slot. |
| Use either a branch that annuls when the condition if true or |
| invert the test with a branch that annuls when the condition is |
| false. This saves insns, since otherwise we must copy an insn |
| from the L1 target. |
| |
| (orig) (skip) (otherwise) |
| Bcc.n L1 Bcc',a L1 Bcc,a L1' |
| insn insn insn2 |
| L1: L1: L1: |
| insn2 insn2 insn2 |
| insn3 insn3 L1': |
| insn3 |
| |
| 2. When a conditional branch skips over only one instruction, |
| and after that, it unconditionally branches somewhere else, |
| perform the similar optimization. This saves executing the |
| second branch in the case where the inverted condition is true. |
| |
| Bcc.n L1 Bcc',a L2 |
| insn insn |
| L1: L1: |
| Bra L2 Bra L2 |
| |
| INSN is a JUMP_INSN. |
| |
| This should be expanded to skip over N insns, where N is the number |
| of delay slots required. */ |
| |
| static void |
| optimize_skip (rtx_jump_insn *insn, vec<rtx_insn *> *delay_list) |
| { |
| rtx_insn *trial = next_nonnote_insn (insn); |
| rtx_insn *next_trial = next_active_insn (trial); |
| int flags; |
| |
| flags = get_jump_flags (insn, JUMP_LABEL (insn)); |
| |
| if (trial == 0 |
| || !NONJUMP_INSN_P (trial) |
| || GET_CODE (PATTERN (trial)) == SEQUENCE |
| || recog_memoized (trial) < 0 |
| || (! eligible_for_annul_false (insn, 0, trial, flags) |
| && ! eligible_for_annul_true (insn, 0, trial, flags)) |
| || RTX_FRAME_RELATED_P (trial) |
| || can_throw_internal (trial)) |
| return; |
| |
| /* There are two cases where we are just executing one insn (we assume |
| here that a branch requires only one insn; this should be generalized |
| at some point): Where the branch goes around a single insn or where |
| we have one insn followed by a branch to the same label we branch to. |
| In both of these cases, inverting the jump and annulling the delay |
| slot give the same effect in fewer insns. */ |
| if (next_trial == next_active_insn (JUMP_LABEL_AS_INSN (insn)) |
| || (next_trial != 0 |
| && simplejump_or_return_p (next_trial) |
| && JUMP_LABEL (insn) == JUMP_LABEL (next_trial))) |
| { |
| if (eligible_for_annul_false (insn, 0, trial, flags)) |
| { |
| if (invert_jump (insn, JUMP_LABEL (insn), 1)) |
| INSN_FROM_TARGET_P (trial) = 1; |
| else if (! eligible_for_annul_true (insn, 0, trial, flags)) |
| return; |
| } |
| |
| add_to_delay_list (trial, delay_list); |
| next_trial = next_active_insn (trial); |
| update_block (trial, trial); |
| delete_related_insns (trial); |
| |
| /* Also, if we are targeting an unconditional |
| branch, thread our jump to the target of that branch. Don't |
| change this into a RETURN here, because it may not accept what |
| we have in the delay slot. We'll fix this up later. */ |
| if (next_trial && simplejump_or_return_p (next_trial)) |
| { |
| rtx target_label = JUMP_LABEL (next_trial); |
| if (ANY_RETURN_P (target_label)) |
| target_label = find_end_label (target_label); |
| |
| if (target_label) |
| { |
| /* Recompute the flags based on TARGET_LABEL since threading |
| the jump to TARGET_LABEL may change the direction of the |
| jump (which may change the circumstances in which the |
| delay slot is nullified). */ |
| flags = get_jump_flags (insn, target_label); |
| if (eligible_for_annul_true (insn, 0, trial, flags)) |
| reorg_redirect_jump (insn, target_label); |
| } |
| } |
| |
| INSN_ANNULLED_BRANCH_P (insn) = 1; |
| } |
| } |
| |
| /* Encode and return branch direction and prediction information for |
| INSN assuming it will jump to LABEL. |
| |
| Non conditional branches return no direction information and |
| are predicted as very likely taken. */ |
| |
| static int |
| get_jump_flags (const rtx_insn *insn, rtx label) |
| { |
| int flags; |
| |
| /* get_jump_flags can be passed any insn with delay slots, these may |
| be INSNs, CALL_INSNs, or JUMP_INSNs. Only JUMP_INSNs have branch |
| direction information, and only if they are conditional jumps. |
| |
| If LABEL is a return, then there is no way to determine the branch |
| direction. */ |
| if (JUMP_P (insn) |
| && (condjump_p (insn) || condjump_in_parallel_p (insn)) |
| && !ANY_RETURN_P (label) |
| && INSN_UID (insn) <= max_uid |
| && INSN_UID (label) <= max_uid) |
| flags |
| = (uid_to_ruid[INSN_UID (label)] > uid_to_ruid[INSN_UID (insn)]) |
| ? ATTR_FLAG_forward : ATTR_FLAG_backward; |
| /* No valid direction information. */ |
| else |
| flags = 0; |
| |
| return flags; |
| } |
| |
| /* Return truth value of the statement that this branch |
| is mostly taken. If we think that the branch is extremely likely |
| to be taken, we return 2. If the branch is slightly more likely to be |
| taken, return 1. If the branch is slightly less likely to be taken, |
| return 0 and if the branch is highly unlikely to be taken, return -1. */ |
| |
| static int |
| mostly_true_jump (rtx jump_insn) |
| { |
| /* If branch probabilities are available, then use that number since it |
| always gives a correct answer. */ |
| rtx note = find_reg_note (jump_insn, REG_BR_PROB, 0); |
| if (note) |
| { |
| int prob = profile_probability::from_reg_br_prob_note (XINT (note, 0)) |
| .to_reg_br_prob_base (); |
| |
| if (prob >= REG_BR_PROB_BASE * 9 / 10) |
| return 2; |
| else if (prob >= REG_BR_PROB_BASE / 2) |
| return 1; |
| else if (prob >= REG_BR_PROB_BASE / 10) |
| return 0; |
| else |
| return -1; |
| } |
| |
| /* If there is no note, assume branches are not taken. |
| This should be rare. */ |
| return 0; |
| } |
| |
| /* Return the condition under which INSN will branch to TARGET. If TARGET |
| is zero, return the condition under which INSN will return. If INSN is |
| an unconditional branch, return const_true_rtx. If INSN isn't a simple |
| type of jump, or it doesn't go to TARGET, return 0. */ |
| |
| static rtx |
| get_branch_condition (const rtx_insn *insn, rtx target) |
| { |
| rtx pat = PATTERN (insn); |
| rtx src; |
| |
| if (condjump_in_parallel_p (insn)) |
| pat = XVECEXP (pat, 0, 0); |
| |
| if (ANY_RETURN_P (pat) && pat == target) |
| return const_true_rtx; |
| |
| if (GET_CODE (pat) != SET || SET_DEST (pat) != pc_rtx) |
| return 0; |
| |
| src = SET_SRC (pat); |
| if (GET_CODE (src) == LABEL_REF && label_ref_label (src) == target) |
| return const_true_rtx; |
| |
| else if (GET_CODE (src) == IF_THEN_ELSE |
| && XEXP (src, 2) == pc_rtx |
| && ((GET_CODE (XEXP (src, 1)) == LABEL_REF |
| && label_ref_label (XEXP (src, 1)) == target) |
| || (ANY_RETURN_P (XEXP (src, 1)) && XEXP (src, 1) == target))) |
| return XEXP (src, 0); |
| |
| else if (GET_CODE (src) == IF_THEN_ELSE |
| && XEXP (src, 1) == pc_rtx |
| && ((GET_CODE (XEXP (src, 2)) == LABEL_REF |
| && label_ref_label (XEXP (src, 2)) == target) |
| || (ANY_RETURN_P (XEXP (src, 2)) && XEXP (src, 2) == target))) |
| { |
| enum rtx_code rev; |
| rev = reversed_comparison_code (XEXP (src, 0), insn); |
| if (rev != UNKNOWN) |
| return gen_rtx_fmt_ee (rev, GET_MODE (XEXP (src, 0)), |
| XEXP (XEXP (src, 0), 0), |
| XEXP (XEXP (src, 0), 1)); |
| } |
| |
| return 0; |
| } |
| |
| /* Return nonzero if CONDITION is more strict than the condition of |
| INSN, i.e., if INSN will always branch if CONDITION is true. */ |
| |
| static int |
| condition_dominates_p (rtx condition, const rtx_insn *insn) |
| { |
| rtx other_condition = get_branch_condition (insn, JUMP_LABEL (insn)); |
| enum rtx_code code = GET_CODE (condition); |
| enum rtx_code other_code; |
| |
| if (rtx_equal_p (condition, other_condition) |
| || other_condition == const_true_rtx) |
| return 1; |
| |
| else if (condition == const_true_rtx || other_condition == 0) |
| return 0; |
| |
| other_code = GET_CODE (other_condition); |
| if (GET_RTX_LENGTH (code) != 2 || GET_RTX_LENGTH (other_code) != 2 |
| || ! rtx_equal_p (XEXP (condition, 0), XEXP (other_condition, 0)) |
| || ! rtx_equal_p (XEXP (condition, 1), XEXP (other_condition, 1))) |
| return 0; |
| |
| return comparison_dominates_p (code, other_code); |
| } |
| |
| /* Return nonzero if redirecting JUMP to NEWLABEL does not invalidate |
| any insns already in the delay slot of JUMP. */ |
| |
| static int |
| redirect_with_delay_slots_safe_p (rtx_insn *jump, rtx newlabel, rtx seq) |
| { |
| int flags, i; |
| rtx_sequence *pat = as_a <rtx_sequence *> (PATTERN (seq)); |
| |
| /* Make sure all the delay slots of this jump would still |
| be valid after threading the jump. If they are still |
| valid, then return nonzero. */ |
| |
| flags = get_jump_flags (jump, newlabel); |
| for (i = 1; i < pat->len (); i++) |
| if (! ( |
| #if ANNUL_IFFALSE_SLOTS |
| (INSN_ANNULLED_BRANCH_P (jump) |
| && INSN_FROM_TARGET_P (pat->insn (i))) |
| ? eligible_for_annul_false (jump, i - 1, pat->insn (i), flags) : |
| #endif |
| #if ANNUL_IFTRUE_SLOTS |
| (INSN_ANNULLED_BRANCH_P (jump) |
| && ! INSN_FROM_TARGET_P (XVECEXP (pat, 0, i))) |
| ? eligible_for_annul_true (jump, i - 1, pat->insn (i), flags) : |
| #endif |
| eligible_for_delay (jump, i - 1, pat->insn (i), flags))) |
| break; |
| |
| return (i == pat->len ()); |
| } |
| |
| /* Return nonzero if redirecting JUMP to NEWLABEL does not invalidate |
| any insns we wish to place in the delay slot of JUMP. */ |
| |
| static int |
| redirect_with_delay_list_safe_p (rtx_insn *jump, rtx newlabel, |
| const vec<rtx_insn *> &delay_list) |
| { |
| /* Make sure all the insns in DELAY_LIST would still be |
| valid after threading the jump. If they are still |
| valid, then return nonzero. */ |
| |
| int flags = get_jump_flags (jump, newlabel); |
| unsigned int delay_insns = delay_list.length (); |
| unsigned int i = 0; |
| for (; i < delay_insns; i++) |
| if (! ( |
| #if ANNUL_IFFALSE_SLOTS |
| (INSN_ANNULLED_BRANCH_P (jump) |
| && INSN_FROM_TARGET_P (delay_list[i])) |
| ? eligible_for_annul_false (jump, i, delay_list[i], flags) : |
| #endif |
| #if ANNUL_IFTRUE_SLOTS |
| (INSN_ANNULLED_BRANCH_P (jump) |
| && ! INSN_FROM_TARGET_P (delay_list[i])) |
| ? eligible_for_annul_true (jump, i, delay_list[i], flags) : |
| #endif |
| eligible_for_delay (jump, i, delay_list[i], flags))) |
| break; |
| |
| return i == delay_insns; |
| } |
| |
| /* DELAY_LIST is a list of insns that have already been placed into delay |
| slots. See if all of them have the same annulling status as ANNUL_TRUE_P. |
| If not, return 0; otherwise return 1. */ |
| |
| static int |
| check_annul_list_true_false (int annul_true_p, |
| const vec<rtx_insn *> &delay_list) |
| { |
| rtx_insn *trial; |
| unsigned int i; |
| FOR_EACH_VEC_ELT (delay_list, i, trial) |
| if ((annul_true_p && INSN_FROM_TARGET_P (trial)) |
| || (!annul_true_p && !INSN_FROM_TARGET_P (trial))) |
| return 0; |
| |
| return 1; |
| } |
| |
| /* INSN branches to an insn whose pattern SEQ is a SEQUENCE. Given that |
| the condition tested by INSN is CONDITION and the resources shown in |
| OTHER_NEEDED are needed after INSN, see whether INSN can take all the insns |
| from SEQ's delay list, in addition to whatever insns it may execute |
| (in DELAY_LIST). SETS and NEEDED are denote resources already set and |
| needed while searching for delay slot insns. Return the concatenated |
| delay list if possible, otherwise, return 0. |
| |
| SLOTS_TO_FILL is the total number of slots required by INSN, and |
| PSLOTS_FILLED points to the number filled so far (also the number of |
| insns in DELAY_LIST). It is updated with the number that have been |
| filled from the SEQUENCE, if any. |
| |
| PANNUL_P points to a nonzero value if we already know that we need |
| to annul INSN. If this routine determines that annulling is needed, |
| it may set that value nonzero. |
| |
| PNEW_THREAD points to a location that is to receive the place at which |
| execution should continue. */ |
| |
| static void |
| steal_delay_list_from_target (rtx_insn *insn, rtx condition, rtx_sequence *seq, |
| vec<rtx_insn *> *delay_list, resources *sets, |
| struct resources *needed, |
| struct resources *other_needed, |
| int slots_to_fill, int *pslots_filled, |
| int *pannul_p, rtx *pnew_thread) |
| { |
| int slots_remaining = slots_to_fill - *pslots_filled; |
| int total_slots_filled = *pslots_filled; |
| auto_vec<rtx_insn *, 5> new_delay_list; |
| int must_annul = *pannul_p; |
| int used_annul = 0; |
| int i; |
| struct resources cc_set; |
| bool *redundant; |
| |
| /* We can't do anything if there are more delay slots in SEQ than we |
| can handle, or if we don't know that it will be a taken branch. |
| We know that it will be a taken branch if it is either an unconditional |
| branch or a conditional branch with a stricter branch condition. |
| |
| Also, exit if the branch has more than one set, since then it is computing |
| other results that can't be ignored, e.g. the HPPA mov&branch instruction. |
| ??? It may be possible to move other sets into INSN in addition to |
| moving the instructions in the delay slots. |
| |
| We can not steal the delay list if one of the instructions in the |
| current delay_list modifies the condition codes and the jump in the |
| sequence is a conditional jump. We can not do this because we can |
| not change the direction of the jump because the condition codes |
| will effect the direction of the jump in the sequence. */ |
| |
| CLEAR_RESOURCE (&cc_set); |
| |
| rtx_insn *trial; |
| FOR_EACH_VEC_ELT (*delay_list, i, trial) |
| { |
| mark_set_resources (trial, &cc_set, 0, MARK_SRC_DEST_CALL); |
| if (insn_references_resource_p (seq->insn (0), &cc_set, false)) |
| return; |
| } |
| |
| if (XVECLEN (seq, 0) - 1 > slots_remaining |
| || ! condition_dominates_p (condition, seq->insn (0)) |
| || ! single_set (seq->insn (0))) |
| return; |
| |
| /* On some targets, branches with delay slots can have a limited |
| displacement. Give the back end a chance to tell us we can't do |
| this. */ |
| if (! targetm.can_follow_jump (insn, seq->insn (0))) |
| return; |
| |
| redundant = XALLOCAVEC (bool, XVECLEN (seq, 0)); |
| for (i = 1; i < seq->len (); i++) |
| { |
| rtx_insn *trial = seq->insn (i); |
| int flags; |
| |
| if (insn_references_resource_p (trial, sets, false) |
| || insn_sets_resource_p (trial, needed, false) |
| || insn_sets_resource_p (trial, sets, false) |
| /* If TRIAL sets CC0, we can't copy it, so we can't steal this |
| delay list. */ |
| || (HAVE_cc0 && find_reg_note (trial, REG_CC_USER, NULL_RTX)) |
| /* If TRIAL is from the fallthrough code of an annulled branch insn |
| in SEQ, we cannot use it. */ |
| || (INSN_ANNULLED_BRANCH_P (seq->insn (0)) |
| && ! INSN_FROM_TARGET_P (trial))) |
| return; |
| |
| /* If this insn was already done (usually in a previous delay slot), |
| pretend we put it in our delay slot. */ |
| redundant[i] = redundant_insn (trial, insn, new_delay_list); |
| if (redundant[i]) |
| continue; |
| |
| /* We will end up re-vectoring this branch, so compute flags |
| based on jumping to the new label. */ |
| flags = get_jump_flags (insn, JUMP_LABEL (seq->insn (0))); |
| |
| if (! must_annul |
| && ((condition == const_true_rtx |
| || (! insn_sets_resource_p (trial, other_needed, false) |
| && ! may_trap_or_fault_p (PATTERN (trial))))) |
| ? eligible_for_delay (insn, total_slots_filled, trial, flags) |
| : (must_annul || (delay_list->is_empty () && new_delay_list.is_empty ())) |
| && (must_annul = 1, |
| check_annul_list_true_false (0, *delay_list) |
| && check_annul_list_true_false (0, new_delay_list) |
| && eligible_for_annul_false (insn, total_slots_filled, |
| trial, flags))) |
| { |
| if (must_annul) |
| { |
| /* Frame related instructions cannot go into annulled delay |
| slots, it messes up the dwarf info. */ |
| if (RTX_FRAME_RELATED_P (trial)) |
| return; |
| used_annul = 1; |
| } |
| rtx_insn *temp = copy_delay_slot_insn (trial); |
| INSN_FROM_TARGET_P (temp) = 1; |
| add_to_delay_list (temp, &new_delay_list); |
| total_slots_filled++; |
| |
| if (--slots_remaining == 0) |
| break; |
| } |
| else |
| return; |
| } |
| |
| /* Record the effect of the instructions that were redundant and which |
| we therefore decided not to copy. */ |
| for (i = 1; i < seq->len (); i++) |
| if (redundant[i]) |
| update_block (seq->insn (i), insn); |
| |
| /* Show the place to which we will be branching. */ |
| *pnew_thread = first_active_target_insn (JUMP_LABEL (seq->insn (0))); |
| |
| /* Add any new insns to the delay list and update the count of the |
| number of slots filled. */ |
| *pslots_filled = total_slots_filled; |
| if (used_annul) |
| *pannul_p = 1; |
| |
| rtx_insn *temp; |
| FOR_EACH_VEC_ELT (new_delay_list, i, temp) |
| add_to_delay_list (temp, delay_list); |
| } |
| |
| /* Similar to steal_delay_list_from_target except that SEQ is on the |
| fallthrough path of INSN. Here we only do something if the delay insn |
| of SEQ is an unconditional branch. In that case we steal its delay slot |
| for INSN since unconditional branches are much easier to fill. */ |
| |
| static void |
| steal_delay_list_from_fallthrough (rtx_insn *insn, rtx condition, |
| rtx_sequence *seq, |
| vec<rtx_insn *> *delay_list, |
| struct resources *sets, |
| struct resources *needed, |
| struct resources *other_needed, |
| int slots_to_fill, int *pslots_filled, |
| int *pannul_p) |
| { |
| int i; |
| int flags; |
| int must_annul = *pannul_p; |
| int used_annul = 0; |
| |
| flags = get_jump_flags (insn, JUMP_LABEL (insn)); |
| |
| /* We can't do anything if SEQ's delay insn isn't an |
| unconditional branch. */ |
| |
| if (! simplejump_or_return_p (seq->insn (0))) |
| return; |
| |
| for (i = 1; i < seq->len (); i++) |
| { |
| rtx_insn *trial = seq->insn (i); |
| |
| /* If TRIAL sets CC0, stealing it will move it too far from the use |
| of CC0. */ |
| if (insn_references_resource_p (trial, sets, false) |
| || insn_sets_resource_p (trial, needed, false) |
| || insn_sets_resource_p (trial, sets, false) |
| || (HAVE_cc0 && sets_cc0_p (PATTERN (trial)))) |
| |
| break; |
| |
| /* If this insn was already done, we don't need it. */ |
| if (redundant_insn (trial, insn, *delay_list)) |
| { |
| update_block (trial, insn); |
| delete_from_delay_slot (trial); |
| continue; |
| } |
| |
| if (! must_annul |
| && ((condition == const_true_rtx |
| || (! insn_sets_resource_p (trial, other_needed, false) |
| && ! may_trap_or_fault_p (PATTERN (trial))))) |
| ? eligible_for_delay (insn, *pslots_filled, trial, flags) |
| : (must_annul || delay_list->is_empty ()) && (must_annul = 1, |
| check_annul_list_true_false (1, *delay_list) |
| && eligible_for_annul_true (insn, *pslots_filled, trial, flags))) |
| { |
| if (must_annul) |
| used_annul = 1; |
| delete_from_delay_slot (trial); |
| add_to_delay_list (trial, delay_list); |
| |
| if (++(*pslots_filled) == slots_to_fill) |
| break; |
| } |
| else |
| break; |
| } |
| |
| if (used_annul) |
| *pannul_p = 1; |
| } |
| |
| /* Try merging insns starting at THREAD which match exactly the insns in |
| INSN's delay list. |
| |
| If all insns were matched and the insn was previously annulling, the |
| annul bit will be cleared. |
| |
| For each insn that is merged, if the branch is or will be non-annulling, |
| we delete the merged insn. */ |
| |
| static void |
| try_merge_delay_insns (rtx_insn *insn, rtx_insn *thread) |
| { |
| rtx_insn *trial, *next_trial; |
| rtx_insn *delay_insn = as_a <rtx_insn *> (XVECEXP (PATTERN (insn), 0, 0)); |
| int annul_p = JUMP_P (delay_insn) && INSN_ANNULLED_BRANCH_P (delay_insn); |
| int slot_number = 1; |
| int num_slots = XVECLEN (PATTERN (insn), 0); |
| rtx next_to_match = XVECEXP (PATTERN (insn), 0, slot_number); |
| struct resources set, needed, modified; |
| auto_vec<std::pair<rtx_insn *, bool>, 10> merged_insns; |
| int flags; |
| |
| flags = get_jump_flags (delay_insn, JUMP_LABEL (delay_insn)); |
| |
| CLEAR_RESOURCE (&needed); |
| CLEAR_RESOURCE (&set); |
| |
| /* If this is not an annulling branch, take into account anything needed in |
| INSN's delay slot. This prevents two increments from being incorrectly |
| folded into one. If we are annulling, this would be the correct |
| thing to do. (The alternative, looking at things set in NEXT_TO_MATCH |
| will essentially disable this optimization. This method is somewhat of |
| a kludge, but I don't see a better way.) */ |
| if (! annul_p) |
| for (int i = 1; i < num_slots; i++) |
| if (XVECEXP (PATTERN (insn), 0, i)) |
| mark_referenced_resources (XVECEXP (PATTERN (insn), 0, i), &needed, |
| true); |
| |
| for (trial = thread; !stop_search_p (trial, 1); trial = next_trial) |
| { |
| rtx pat = PATTERN (trial); |
| rtx oldtrial = trial; |
| |
| next_trial = next_nonnote_insn (trial); |
| |
| /* TRIAL must be a CALL_INSN or INSN. Skip USE and CLOBBER. */ |
| if (NONJUMP_INSN_P (trial) |
| && (GET_CODE (pat) == USE || GET_CODE (pat) == CLOBBER)) |
| continue; |
| |
| if (GET_CODE (next_to_match) == GET_CODE (trial) |
| /* We can't share an insn that sets cc0. */ |
| && (!HAVE_cc0 || ! sets_cc0_p (pat)) |
| && ! insn_references_resource_p (trial, &set, true) |
| && ! insn_sets_resource_p (trial, &set, true) |
| && ! insn_sets_resource_p (trial, &needed, true) |
| && (trial = try_split (pat, trial, 0)) != 0 |
| /* Update next_trial, in case try_split succeeded. */ |
| && (next_trial = next_nonnote_insn (trial)) |
| /* Likewise THREAD. */ |
| && (thread = oldtrial == thread ? trial : thread) |
| && rtx_equal_p (PATTERN (next_to_match), PATTERN (trial)) |
| /* Have to test this condition if annul condition is different |
| from (and less restrictive than) non-annulling one. */ |
| && eligible_for_delay (delay_insn, slot_number - 1, trial, flags)) |
| { |
| |
| if (! annul_p) |
| { |
| update_block (trial, thread); |
| if (trial == thread) |
| thread = next_active_insn (thread); |
| |
| delete_related_insns (trial); |
| INSN_FROM_TARGET_P (next_to_match) = 0; |
| } |
| else |
| merged_insns.safe_push (std::pair<rtx_insn *, bool> (trial, false)); |
| |
| if (++slot_number == num_slots) |
| break; |
| |
| next_to_match = XVECEXP (PATTERN (insn), 0, slot_number); |
| } |
| |
| mark_set_resources (trial, &set, 0, MARK_SRC_DEST_CALL); |
| mark_referenced_resources (trial, &needed, true); |
| } |
| |
| /* See if we stopped on a filled insn. If we did, try to see if its |
| delay slots match. */ |
| if (slot_number != num_slots |
| && trial && NONJUMP_INSN_P (trial) |
| && GET_CODE (PATTERN (trial)) == SEQUENCE |
| && !(JUMP_P (XVECEXP (PATTERN (trial), 0, 0)) |
| && INSN_ANNULLED_BRANCH_P (XVECEXP (PATTERN (trial), 0, 0)))) |
| { |
| rtx_sequence *pat = as_a <rtx_sequence *> (PATTERN (trial)); |
| rtx filled_insn = XVECEXP (pat, 0, 0); |
| |
| /* Account for resources set/needed by the filled insn. */ |
| mark_set_resources (filled_insn, &set, 0, MARK_SRC_DEST_CALL); |
| mark_referenced_resources (filled_insn, &needed, true); |
| |
| for (int i = 1; i < pat->len (); i++) |
| { |
| rtx_insn *dtrial = pat->insn (i); |
| |
| CLEAR_RESOURCE (&modified); |
| /* Account for resources set by the insn following NEXT_TO_MATCH |
| inside INSN's delay list. */ |
| for (int j = 1; slot_number + j < num_slots; j++) |
| mark_set_resources (XVECEXP (PATTERN (insn), 0, slot_number + j), |
| &modified, 0, MARK_SRC_DEST_CALL); |
| /* Account for resources set by the insn before DTRIAL and inside |
| TRIAL's delay list. */ |
| for (int j = 1; j < i; j++) |
| mark_set_resources (XVECEXP (pat, 0, j), |
| &modified, 0, MARK_SRC_DEST_CALL); |
| if (! insn_references_resource_p (dtrial, &set, true) |
| && ! insn_sets_resource_p (dtrial, &set, true) |
| && ! insn_sets_resource_p (dtrial, &needed, true) |
| && (!HAVE_cc0 || ! sets_cc0_p (PATTERN (dtrial))) |
| && rtx_equal_p (PATTERN (next_to_match), PATTERN (dtrial)) |
| /* Check that DTRIAL and NEXT_TO_MATCH does not reference a |
| resource modified between them (only dtrial is checked because |
| next_to_match and dtrial shall to be equal in order to hit |
| this line) */ |
| && ! insn_references_resource_p (dtrial, &modified, true) |
| && eligible_for_delay (delay_insn, slot_number - 1, dtrial, flags)) |
| { |
| if (! annul_p) |
| { |
| rtx_insn *new_rtx; |
| |
| update_block (dtrial, thread); |
| new_rtx = delete_from_delay_slot (dtrial); |
| if (thread->deleted ()) |
| thread = new_rtx; |
| INSN_FROM_TARGET_P (next_to_match) = 0; |
| } |
| else |
| merged_insns.safe_push (std::pair<rtx_insn *, bool> (dtrial, |
| true)); |
| |
| if (++slot_number == num_slots) |
| break; |
| |
| next_to_match = XVECEXP (PATTERN (insn), 0, slot_number); |
| } |
| else |
| { |
| /* Keep track of the set/referenced resources for the delay |
| slots of any trial insns we encounter. */ |
| mark_set_resources (dtrial, &set, 0, MARK_SRC_DEST_CALL); |
| mark_referenced_resources (dtrial, &needed, true); |
| } |
| } |
| } |
| |
| /* If all insns in the delay slot have been matched and we were previously |
| annulling the branch, we need not any more. In that case delete all the |
| merged insns. Also clear the INSN_FROM_TARGET_P bit of each insn in |
| the delay list so that we know that it isn't only being used at the |
| target. */ |
| if (slot_number == num_slots && annul_p) |
| { |
| unsigned int len = merged_insns.length (); |
| for (unsigned int i = len - 1; i < len; i--) |
| if (merged_insns[i].second) |
| { |
| update_block (merged_insns[i].first, thread); |
| rtx_insn *new_rtx = delete_from_delay_slot (merged_insns[i].first); |
| if (thread->deleted ()) |
| thread = new_rtx; |
| } |
| else |
| { |
| update_block (merged_insns[i].first, thread); |
| delete_related_insns (merged_insns[i].first); |
| } |
| |
| INSN_ANNULLED_BRANCH_P (delay_insn) = 0; |
| |
| for (int i = 0; i < XVECLEN (PATTERN (insn), 0); i++) |
| INSN_FROM_TARGET_P (XVECEXP (PATTERN (insn), 0, i)) = 0; |
| } |
| } |
| |
| /* See if INSN is redundant with an insn in front of TARGET. Often this |
| is called when INSN is a candidate for a delay slot of TARGET. |
| DELAY_LIST are insns that will be placed in delay slots of TARGET in front |
| of INSN. Often INSN will be redundant with an insn in a delay slot of |
| some previous insn. This happens when we have a series of branches to the |
| same label; in that case the first insn at the target might want to go |
| into each of the delay slots. |
| |
| If we are not careful, this routine can take up a significant fraction |
| of the total compilation time (4%), but only wins rarely. Hence we |
| speed this routine up by making two passes. The first pass goes back |
| until it hits a label and sees if it finds an insn with an identical |
| pattern. Only in this (relatively rare) event does it check for |
| data conflicts. |
| |
| We do not split insns we encounter. This could cause us not to find a |
| redundant insn, but the cost of splitting seems greater than the possible |
| gain in rare cases. */ |
| |
| static rtx_insn * |
| redundant_insn (rtx insn, rtx_insn *target, const vec<rtx_insn *> &delay_list) |
| { |
| rtx target_main = target; |
| rtx ipat = PATTERN (insn); |
| rtx_insn *trial; |
| rtx pat; |
| struct resources needed, set; |
| int i; |
| unsigned insns_to_search; |
| |
| /* If INSN has any REG_UNUSED notes, it can't match anything since we |
| are allowed to not actually assign to such a register. */ |
| if (find_reg_note (insn, REG_UNUSED, NULL_RTX) != 0) |
| return 0; |
| |
| /* Scan backwards looking for a match. */ |
| for (trial = PREV_INSN (target), |
| insns_to_search = MAX_DELAY_SLOT_INSN_SEARCH; |
| trial && insns_to_search > 0; |
| trial = PREV_INSN (trial)) |
| { |
| /* (use (insn))s can come immediately after a barrier if the |
| label that used to precede them has been deleted as dead. |
| See delete_related_insns. */ |
| if (LABEL_P (trial) || BARRIER_P (trial)) |
| return 0; |
| |
| if (!INSN_P (trial)) |
| continue; |
| --insns_to_search; |
| |
| pat = PATTERN (trial); |
| if (GET_CODE (pat) == USE || GET_CODE (pat) == CLOBBER) |
| continue; |
| |
| if (rtx_sequence *seq = dyn_cast <rtx_sequence *> (pat)) |
| { |
| /* Stop for a CALL and its delay slots because it is difficult to |
| track its resource needs correctly. */ |
| if (CALL_P (seq->element (0))) |
| return 0; |
| |
| /* Stop for an INSN or JUMP_INSN with delayed effects and its delay |
| slots because it is difficult to track its resource needs |
| correctly. */ |
| |
| if (INSN_SETS_ARE_DELAYED (seq->insn (0))) |
| return 0; |
| |
| if (INSN_REFERENCES_ARE_DELAYED (seq->insn (0))) |
| return 0; |
| |
| /* See if any of the insns in the delay slot match, updating |
| resource requirements as we go. */ |
| for (i = seq->len () - 1; i > 0; i--) |
| if (GET_CODE (seq->element (i)) == GET_CODE (insn) |
| && rtx_equal_p (PATTERN (seq->element (i)), ipat) |
| && ! find_reg_note (seq->element (i), REG_UNUSED, NULL_RTX)) |
| break; |
| |
| /* If found a match, exit this loop early. */ |
| if (i > 0) |
| break; |
| } |
| |
| else if (GET_CODE (trial) == GET_CODE (insn) && rtx_equal_p (pat, ipat) |
| && ! find_reg_note (trial, REG_UNUSED, NULL_RTX)) |
| break; |
| } |
| |
| /* If we didn't find an insn that matches, return 0. */ |
| if (trial == 0) |
| return 0; |
| |
| /* See what resources this insn sets and needs. If they overlap, or |
| if this insn references CC0, it can't be redundant. */ |
| |
| CLEAR_RESOURCE (&needed); |
| CLEAR_RESOURCE (&set); |
| mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL); |
| mark_referenced_resources (insn, &needed, true); |
| |
| /* If TARGET is a SEQUENCE, get the main insn. */ |
| if (NONJUMP_INSN_P (target) && GET_CODE (PATTERN (target)) == SEQUENCE) |
| target_main = XVECEXP (PATTERN (target), 0, 0); |
| |
| if (resource_conflicts_p (&needed, &set) |
| || (HAVE_cc0 && reg_mentioned_p (cc0_rtx, ipat)) |
| /* The insn requiring the delay may not set anything needed or set by |
| INSN. */ |
| || insn_sets_resource_p (target_main, &needed, true) |
| || insn_sets_resource_p (target_main, &set, true)) |
| return 0; |
| |
| /* Insns we pass may not set either NEEDED or SET, so merge them for |
| simpler tests. */ |
| needed.memory |= set.memory; |
| IOR_HARD_REG_SET (needed.regs, set.regs); |
| |
| /* This insn isn't redundant if it conflicts with an insn that either is |
| or will be in a delay slot of TARGET. */ |
| |
| unsigned int j; |
| rtx_insn *temp; |
| FOR_EACH_VEC_ELT (delay_list, j, temp) |
| if (insn_sets_resource_p (temp, &needed, true)) |
| return 0; |
| |
| if (NONJUMP_INSN_P (target) && GET_CODE (PATTERN (target)) == SEQUENCE) |
| for (i = 1; i < XVECLEN (PATTERN (target), 0); i++) |
| if (insn_sets_resource_p (XVECEXP (PATTERN (target), 0, i), &needed, |
| true)) |
| return 0; |
| |
| /* Scan backwards until we reach a label or an insn that uses something |
| INSN sets or sets something insn uses or sets. */ |
| |
| for (trial = PREV_INSN (target), |
| insns_to_search = MAX_DELAY_SLOT_INSN_SEARCH; |
| trial && !LABEL_P (trial) && insns_to_search > 0; |
| trial = PREV_INSN (trial)) |
| { |
| if (!INSN_P (trial)) |
| continue; |
| --insns_to_search; |
| |
| pat = PATTERN (trial); |
| if (GET_CODE (pat) == USE || GET_CODE (pat) == CLOBBER) |
| continue; |
| |
| if (rtx_sequence *seq = dyn_cast <rtx_sequence *> (pat)) |
| { |
| bool annul_p = false; |
| rtx_insn *control = seq->insn (0); |
| |
| /* If this is a CALL_INSN and its delay slots, it is hard to track |
| the resource needs properly, so give up. */ |
| if (CALL_P (control)) |
| return 0; |
| |
| /* If this is an INSN or JUMP_INSN with delayed effects, it |
| is hard to track the resource needs properly, so give up. */ |
| |
| if (INSN_SETS_ARE_DELAYED (control)) |
| return 0; |
| |
| if (INSN_REFERENCES_ARE_DELAYED (control)) |
| return 0; |
| |
| if (JUMP_P (control)) |
| annul_p = INSN_ANNULLED_BRANCH_P (control); |
| |
| /* See if any of the insns in the delay slot match, updating |
| resource requirements as we go. */ |
| for (i = seq->len () - 1; i > 0; i--) |
| { |
| rtx_insn *candidate = seq->insn (i); |
| |
| /* If an insn will be annulled if the branch is false, it isn't |
| considered as a possible duplicate insn. */ |
| if (rtx_equal_p (PATTERN (candidate), ipat) |
| && ! (annul_p && INSN_FROM_TARGET_P (candidate))) |
| { |
| /* Show that this insn will be used in the sequel. */ |
| INSN_FROM_TARGET_P (candidate) = 0; |
| return candidate; |
| } |
| |
| /* Unless this is an annulled insn from the target of a branch, |
| we must stop if it sets anything needed or set by INSN. */ |
| if ((!annul_p || !INSN_FROM_TARGET_P (candidate)) |
| && insn_sets_resource_p (candidate, &needed, true)) |
| return 0; |
| } |
| |
| /* If the insn requiring the delay slot conflicts with INSN, we |
| must stop. */ |
| if (insn_sets_resource_p (control, &needed, true)) |
| return 0; |
| } |
| else |
| { |
| /* See if TRIAL is the same as INSN. */ |
| pat = PATTERN (trial); |
| if (rtx_equal_p (pat, ipat)) |
| return trial; |
| |
| /* Can't go any further if TRIAL conflicts with INSN. */ |
| if (insn_sets_resource_p (trial, &needed, true)) |
| return 0; |
| } |
| } |
| |
| return 0; |
| } |
| |
| /* Return 1 if THREAD can only be executed in one way. If LABEL is nonzero, |
| it is the target of the branch insn being scanned. If ALLOW_FALLTHROUGH |
| is nonzero, we are allowed to fall into this thread; otherwise, we are |
| not. |
| |
| If LABEL is used more than one or we pass a label other than LABEL before |
| finding an active insn, we do not own this thread. */ |
| |
| static int |
| own_thread_p (rtx thread, rtx label, int allow_fallthrough) |
| { |
| rtx_insn *active_insn; |
| rtx_insn *insn; |
| |
| /* We don't own the function end. */ |
| if (thread == 0 || ANY_RETURN_P (thread)) |
| return 0; |
| |
| /* We have a non-NULL insn. */ |
| rtx_insn *thread_insn = as_a <rtx_insn *> (thread); |
| |
| /* Get the first active insn, or THREAD_INSN, if it is an active insn. */ |
| active_insn = next_active_insn (PREV_INSN (thread_insn)); |
| |
| for (insn = thread_insn; insn != active_insn; insn = NEXT_INSN (insn)) |
| if (LABEL_P (insn) |
| && (insn != label || LABEL_NUSES (insn) != 1)) |
| return 0; |
| |
| if (allow_fallthrough) |
| return 1; |
| |
| /* Ensure that we reach a BARRIER before any insn or label. */ |
| for (insn = prev_nonnote_insn (thread_insn); |
| insn == 0 || !BARRIER_P (insn); |
| insn = prev_nonnote_insn (insn)) |
| if (insn == 0 |
| || LABEL_P (insn) |
| || (NONJUMP_INSN_P (insn) |
| && GET_CODE (PATTERN (insn)) != USE |
| && GET_CODE (PATTERN (insn)) != CLOBBER)) |
| return 0; |
| |
| return 1; |
| } |
| |
| /* Called when INSN is being moved from a location near the target of a jump. |
| We leave a marker of the form (use (INSN)) immediately in front of WHERE |
| for mark_target_live_regs. These markers will be deleted at the end. |
| |
| We used to try to update the live status of registers if WHERE is at |
| the start of a basic block, but that can't work since we may remove a |
| BARRIER in relax_delay_slots. */ |
| |
| static void |
| update_block (rtx_insn *insn, rtx_insn *where) |
| { |
| emit_insn_before (gen_rtx_USE (VOIDmode, insn), where); |
| |
| /* INSN might be making a value live in a block where it didn't use to |
| be. So recompute liveness information for this block. */ |
| incr_ticks_for_insn (insn); |
| } |
| |
| /* Similar to REDIRECT_JUMP except that we update the BB_TICKS entry for |
| the basic block containing the jump. */ |
| |
| static int |
| reorg_redirect_jump (rtx_jump_insn *jump, rtx nlabel) |
| { |
| incr_ticks_for_insn (jump); |
| return redirect_jump (jump, nlabel, 1); |
| } |
| |
| /* Called when INSN is being moved forward into a delay slot of DELAYED_INSN. |
| We check every instruction between INSN and DELAYED_INSN for REG_DEAD notes |
| that reference values used in INSN. If we find one, then we move the |
| REG_DEAD note to INSN. |
| |
| This is needed to handle the case where a later insn (after INSN) has a |
| REG_DEAD note for a register used by INSN, and this later insn subsequently |
| gets moved before a CODE_LABEL because it is a redundant insn. In this |
| case, mark_target_live_regs may be confused into thinking the register |
| is dead because it sees a REG_DEAD note immediately before a CODE_LABEL. */ |
| |
| static void |
| update_reg_dead_notes (rtx_insn *insn, rtx_insn *delayed_insn) |
| { |
| rtx link, next; |
| rtx_insn *p; |
| |
| for (p = next_nonnote_insn (insn); p != delayed_insn; |
| p = next_nonnote_insn (p)) |
| for (link = REG_NOTES (p); link; link = next) |
| { |
| next = XEXP (link, 1); |
| |
| if (REG_NOTE_KIND (link) != REG_DEAD |
| || !REG_P (XEXP (link, 0))) |
| continue; |
| |
| if (reg_referenced_p (XEXP (link, 0), PATTERN (insn))) |
| { |
| /* Move the REG_DEAD note from P to INSN. */ |
| remove_note (p, link); |
| XEXP (link, 1) = REG_NOTES (insn); |
| REG_NOTES (insn) = link; |
| } |
| } |
| } |
| |
| /* Called when an insn redundant with start_insn is deleted. If there |
| is a REG_DEAD note for the target of start_insn between start_insn |
| and stop_insn, then the REG_DEAD note needs to be deleted since the |
| value no longer dies there. |
| |
| If the REG_DEAD note isn't deleted, then mark_target_live_regs may be |
| confused into thinking the register is dead. */ |
| |
| static void |
| fix_reg_dead_note (rtx_insn *start_insn, rtx stop_insn) |
| { |
| rtx link, next; |
| rtx_insn *p; |
| |
| for (p = next_nonnote_insn (start_insn); p != stop_insn; |
| p = next_nonnote_insn (p)) |
| for (link = REG_NOTES (p); link; link = next) |
| { |
| next = XEXP (link, 1); |
| |
| if (REG_NOTE_KIND (link) != REG_DEAD |
| || !REG_P (XEXP (link, 0))) |
| continue; |
| |
| if (reg_set_p (XEXP (link, 0), PATTERN (start_insn))) |
| { |
| remove_note (p, link); |
| return; |
| } |
| } |
| } |
| |
| /* Delete any REG_UNUSED notes that exist on INSN but not on REDUNDANT_INSN. |
| |
| This handles the case of udivmodXi4 instructions which optimize their |
| output depending on whether any REG_UNUSED notes are present. |
| we must make sure that INSN calculates as many results as REDUNDANT_INSN |
| does. */ |
| |
| static void |
| update_reg_unused_notes (rtx_insn *insn, rtx redundant_insn) |
| { |
| rtx link, next; |
| |
| for (link = REG_NOTES (insn); link; link = next) |
| { |
| next = XEXP (link, 1); |
| |
| if (REG_NOTE_KIND (link) != REG_UNUSED |
| || !REG_P (XEXP (link, 0))) |
| continue; |
| |
| if (! find_regno_note (redundant_insn, REG_UNUSED, |
| REGNO (XEXP (link, 0)))) |
| remove_note (insn, link); |
| } |
| } |
| |
| static vec <rtx> sibling_labels; |
| |
| /* Return the label before INSN, or put a new label there. If SIBLING is |
| non-zero, it is another label associated with the new label (if any), |
| typically the former target of the jump that will be redirected to |
| the new label. */ |
| |
| static rtx_insn * |
| get_label_before (rtx_insn *insn, rtx sibling) |
| { |
| rtx_insn *label; |
| |
| /* Find an existing label at this point |
| or make a new one if there is none. */ |
| label = prev_nonnote_insn (insn); |
| |
| if (label == 0 || !LABEL_P (label)) |
| { |
| rtx_insn *prev = PREV_INSN (insn); |
| |
| label = gen_label_rtx (); |
| emit_label_after (label, prev); |
| LABEL_NUSES (label) = 0; |
| if (sibling) |
| { |
| sibling_labels.safe_push (label); |
| sibling_labels.safe_push (sibling); |
| } |
| } |
| return label; |
| } |
| |
| /* Scan a function looking for insns that need a delay slot and find insns to |
| put into the delay slot. |
| |
| NON_JUMPS_P is nonzero if we are to only try to fill non-jump insns (such |
| as calls). We do these first since we don't want jump insns (that are |
| easier to fill) to get the only insns that could be used for non-jump insns. |
| When it is zero, only try to fill JUMP_INSNs. |
| |
| When slots are filled in this manner, the insns (including the |
| delay_insn) are put together in a SEQUENCE rtx. In this fashion, |
| it is possible to tell whether a delay slot has really been filled |
| or not. `final' knows how to deal with this, by communicating |
| through FINAL_SEQUENCE. */ |
| |
| static void |
| fill_simple_delay_slots (int non_jumps_p) |
| { |
| rtx_insn *insn, *trial, *next_trial; |
| rtx pat; |
| int i; |
| int num_unfilled_slots = unfilled_slots_next - unfilled_slots_base; |
| struct resources needed, set; |
| int slots_to_fill, slots_filled; |
| auto_vec<rtx_insn *, 5> delay_list; |
| |
| for (i = 0; i < num_unfilled_slots; i++) |
| { |
| int flags; |
| /* Get the next insn to fill. If it has already had any slots assigned, |
| we can't do anything with it. Maybe we'll improve this later. */ |
| |
| insn = unfilled_slots_base[i]; |
| if (insn == 0 |
| || insn->deleted () |
| || (NONJUMP_INSN_P (insn) |
| && GET_CODE (PATTERN (insn)) == SEQUENCE) |
| || (JUMP_P (insn) && non_jumps_p) |
| || (!JUMP_P (insn) && ! non_jumps_p)) |
| continue; |
| |
| /* It may have been that this insn used to need delay slots, but |
| now doesn't; ignore in that case. This can happen, for example, |
| on the HP PA RISC, where the number of delay slots depends on |
| what insns are nearby. */ |
| slots_to_fill = num_delay_slots (insn); |
| |
| /* Some machine description have defined instructions to have |
| delay slots only in certain circumstances which may depend on |
| nearby insns (which change due to reorg's actions). |
| |
| For example, the PA port normally has delay slots for unconditional |
| jumps. |
| |
| However, the PA port claims such jumps do not have a delay slot |
| if they are immediate successors of certain CALL_INSNs. This |
| allows the port to favor filling the delay slot of the call with |
| the unconditional jump. */ |
| if (slots_to_fill == 0) |
| continue; |
| |
| /* This insn needs, or can use, some delay slots. SLOTS_TO_FILL |
| says how many. After initialization, first try optimizing |
| |
| call _foo call _foo |
| nop add %o7,.-L1,%o7 |
| b,a L1 |
| nop |
| |
| If this case applies, the delay slot of the call is filled with |
| the unconditional jump. This is done first to avoid having the |
| delay slot of the call filled in the backward scan. Also, since |
| the unconditional jump is likely to also have a delay slot, that |
| insn must exist when it is subsequently scanned. |
| |
| This is tried on each insn with delay slots as some machines |
| have insns which perform calls, but are not represented as |
| CALL_INSNs. */ |
| |
| slots_filled = 0; |
| delay_list.truncate (0); |
| |
| if (JUMP_P (insn)) |
| flags = get_jump_flags (insn, JUMP_LABEL (insn)); |
| else |
| flags = get_jump_flags (insn, NULL_RTX); |
| |
| if ((trial = next_active_insn (insn)) |
| && JUMP_P (trial) |
| && simplejump_p (trial) |
| && eligible_for_delay (insn, slots_filled, trial, flags) |
| && no_labels_between_p (insn, trial) |
| && ! can_throw_internal (trial)) |
| { |
| rtx_insn **tmp; |
| slots_filled++; |
| add_to_delay_list (trial, &delay_list); |
| |
| /* TRIAL may have had its delay slot filled, then unfilled. When |
| the delay slot is unfilled, TRIAL is placed back on the unfilled |
| slots obstack. Unfortunately, it is placed on the end of the |
| obstack, not in its original location. Therefore, we must search |
| from entry i + 1 to the end of the unfilled slots obstack to |
| try and find TRIAL. */ |
| tmp = &unfilled_slots_base[i + 1]; |
| while (*tmp != trial && tmp != unfilled_slots_next) |
| tmp++; |
| |
| /* Remove the unconditional jump from consideration for delay slot |
| filling and unthread it. */ |
| if (*tmp == trial) |
| *tmp = 0; |
| { |
| rtx_insn *next = NEXT_INSN (trial); |
| rtx_insn *prev = PREV_INSN (trial); |
| if (prev) |
| SET_NEXT_INSN (prev) = next; |
| if (next) |
| SET_PREV_INSN (next) = prev; |
| } |
| } |
| |
| /* Now, scan backwards from the insn to search for a potential |
| delay-slot candidate. Stop searching when a label or jump is hit. |
| |
| For each candidate, if it is to go into the delay slot (moved |
| forward in execution sequence), it must not need or set any resources |
| that were set by later insns and must not set any resources that |
| are needed for those insns. |
| |
| The delay slot insn itself sets resources unless it is a call |
| (in which case the called routine, not the insn itself, is doing |
| the setting). */ |
| |
| if (slots_filled < slots_to_fill) |
| { |
| /* If the flags register is dead after the insn, then we want to be |
| able to accept a candidate that clobbers it. For this purpose, |
| we need to filter the flags register during life analysis, so |
| that it doesn't create RAW and WAW dependencies, while still |
| creating the necessary WAR dependencies. */ |
| bool filter_flags |
| = (slots_to_fill == 1 |
| && targetm.flags_regnum != INVALID_REGNUM |
| && find_regno_note (insn, REG_DEAD, targetm.flags_regnum)); |
| struct resources fset; |
| CLEAR_RESOURCE (&needed); |
| CLEAR_RESOURCE (&set); |
| mark_set_resources (insn, &set, 0, MARK_SRC_DEST); |
| if (filter_flags) |
| { |
| CLEAR_RESOURCE (&fset); |
| mark_set_resources (insn, &fset, 0, MARK_SRC_DEST); |
| } |
| mark_referenced_resources (insn, &needed, false); |
| |
| for (trial = prev_nonnote_insn (insn); ! stop_search_p (trial, 1); |
| trial = next_trial) |
| { |
| next_trial = prev_nonnote_insn (trial); |
| |
| /* This must be an INSN or CALL_INSN. */ |
| pat = PATTERN (trial); |
| |
| /* Stand-alone USE and CLOBBER are just for flow. */ |
| if (GET_CODE (pat) == USE || GET_CODE (pat) == CLOBBER) |
| continue; |
| |
| /* Check for resource conflict first, to avoid unnecessary |
| splitting. */ |
| if (! insn_references_resource_p (trial, &set, true) |
| && ! insn_sets_resource_p (trial, |
| filter_flags ? &fset : &set, |
| true) |
| && ! insn_sets_resource_p (trial, &needed, true) |
| /* Can't separate set of cc0 from its use. */ |
| && (!HAVE_cc0 || ! (reg_mentioned_p (cc0_rtx, pat) && ! sets_cc0_p (pat))) |
| && ! can_throw_internal (trial)) |
| { |
| trial = try_split (pat, trial, 1); |
| next_trial = prev_nonnote_insn (trial); |
| if (eligible_for_delay (insn, slots_filled, trial, flags)) |
| { |
| /* In this case, we are searching backward, so if we |
| find insns to put on the delay list, we want |
| to put them at the head, rather than the |
| tail, of the list. */ |
| |
| update_reg_dead_notes (trial, insn); |
| delay_list.safe_insert (0, trial); |
| update_block (trial, trial); |
| delete_related_insns (trial); |
| if (slots_to_fill == ++slots_filled) |
| break; |
| continue; |
| } |
| } |
| |
| mark_set_resources (trial, &set, 0, MARK_SRC_DEST_CALL); |
| if (filter_flags) |
| { |
| mark_set_resources (trial, &fset, 0, MARK_SRC_DEST_CALL); |
| /* If the flags register is set, then it doesn't create RAW |
| dependencies any longer and it also doesn't create WAW |
| dependencies since it's dead after the original insn. */ |
| if (TEST_HARD_REG_BIT (fset.regs, targetm.flags_regnum)) |
| { |
| CLEAR_HARD_REG_BIT (needed.regs, targetm.flags_regnum); |
| CLEAR_HARD_REG_BIT (fset.regs, targetm.flags_regnum); |
| } |
| } |
| mark_referenced_resources (trial, &needed, true); |
| } |
| } |
| |
| /* If all needed slots haven't been filled, we come here. */ |
| |
| /* Try to optimize case of jumping around a single insn. */ |
| if ((ANNUL_IFTRUE_SLOTS || ANNUL_IFFALSE_SLOTS) |
| && slots_filled != slots_to_fill |
| && delay_list.is_empty () |
| && JUMP_P (insn) |
| && (condjump_p (insn) || condjump_in_parallel_p (insn)) |
| && !ANY_RETURN_P (JUMP_LABEL (insn))) |
| { |
| optimize_skip (as_a <rtx_jump_insn *> (insn), &delay_list); |
| if (!delay_list.is_empty ()) |
| slots_filled += 1; |
| } |
| |
| /* Try to get insns from beyond the insn needing the delay slot. |
| These insns can neither set or reference resources set in insns being |
| skipped, cannot set resources in the insn being skipped, and, if this |
| is a CALL_INSN (or a CALL_INSN is passed), cannot trap (because the |
| call might not return). |
| |
| There used to be code which continued past the target label if |
| we saw all uses of the target label. This code did not work, |
| because it failed to account for some instructions which were |
| both annulled and marked as from the target. This can happen as a |
| result of optimize_skip. Since this code was redundant with |
| fill_eager_delay_slots anyways, it was just deleted. */ |
| |
| if (slots_filled != slots_to_fill |
| /* If this instruction could throw an exception which is |
| caught in the same function, then it's not safe to fill |
| the delay slot with an instruction from beyond this |
| point. For example, consider: |
| |
| int i = 2; |
| |
| try { |
| f(); |
| i = 3; |
| } catch (...) {} |
| |
| return i; |
| |
| Even though `i' is a local variable, we must be sure not |
| to put `i = 3' in the delay slot if `f' might throw an |
| exception. |
| |
| Presumably, we should also check to see if we could get |
| back to this function via `setjmp'. */ |
| && ! can_throw_internal (insn) |
| && !JUMP_P (insn)) |
| { |
| int maybe_never = 0; |
| rtx pat, trial_delay; |
| |
| CLEAR_RESOURCE (&needed); |
| CLEAR_RESOURCE (&set); |
| mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL); |
| mark_referenced_resources (insn, &needed, true); |
| |
| if (CALL_P (insn)) |
| maybe_never = 1; |
| |
| for (trial = next_nonnote_insn (insn); !stop_search_p (trial, 1); |
| trial = next_trial) |
| { |
| next_trial = next_nonnote_insn (trial); |
| |
| /* This must be an INSN or CALL_INSN. */ |
| pat = PATTERN (trial); |
| |
| /* Stand-alone USE and CLOBBER are just for flow. */ |
| if (GET_CODE (pat) == USE || GET_CODE (pat) == CLOBBER) |
| continue; |
| |
| /* If this already has filled delay slots, get the insn needing |
| the delay slots. */ |
| if (GET_CODE (pat) == SEQUENCE) |
| trial_delay = XVECEXP (pat, 0, 0); |
| else |
| trial_delay = trial; |
| |
| /* Stop our search when seeing a jump. */ |
| if (JUMP_P (trial_delay)) |
| break; |
| |
| /* See if we have a resource problem before we try to split. */ |
| if (GET_CODE (pat) != SEQUENCE |
| && ! insn_references_resource_p (trial, &set, true) |
| && ! insn_sets_resource_p (trial, &set, true) |
| && ! insn_sets_resource_p (trial, &needed, true) |
| && (!HAVE_cc0 && ! (reg_mentioned_p (cc0_rtx, pat) && ! sets_cc0_p (pat))) |
| && ! (maybe_never && may_trap_or_fault_p (pat)) |
| && (trial = try_split (pat, trial, 0)) |
| && eligible_for_delay (insn, slots_filled, trial, flags) |
| && ! can_throw_internal (trial)) |
| { |
| next_trial = next_nonnote_insn (trial); |
| add_to_delay_list (trial, &delay_list); |
| if (HAVE_cc0 && reg_mentioned_p (cc0_rtx, pat)) |
| link_cc0_insns (trial); |
| |
| delete_related_insns (trial); |
| if (slots_to_fill == ++slots_filled) |
| break; |
| continue; |
| } |
| |
| mark_set_resources (trial, &set, 0, MARK_SRC_DEST_CALL); |
| mark_referenced_resources (trial, &needed, true); |
| |
| /* Ensure we don't put insns between the setting of cc and the |
| comparison by moving a setting of cc into an earlier delay |
| slot since these insns could clobber the condition code. */ |
| set.cc = 1; |
| |
| /* If this is a call, we might not get here. */ |
| if (CALL_P (trial_delay)) |
| maybe_never = 1; |
| } |
| |
| /* If there are slots left to fill and our search was stopped by an |
| unconditional branch, try the insn at the branch target. We can |
| redirect the branch if it works. |
| |
| Don't do this if the insn at the branch target is a branch. */ |
| if (slots_to_fill != slots_filled |
| && trial |
| && jump_to_label_p (trial) |
| && simplejump_p (trial) |
| && (next_trial = next_active_insn (JUMP_LABEL_AS_INSN (trial))) != 0 |
| && ! (NONJUMP_INSN_P (next_trial) |
| && GET_CODE (PATTERN (next_trial)) == SEQUENCE) |
| && !JUMP_P (next_trial) |
| && ! insn_references_resource_p (next_trial, &set, true) |
| && ! insn_sets_resource_p (next_trial, &set, true) |
| && ! insn_sets_resource_p (next_trial, &needed, true) |
| && (!HAVE_cc0 || ! reg_mentioned_p (cc0_rtx, PATTERN (next_trial))) |
| && ! (maybe_never && may_trap_or_fault_p (PATTERN (next_trial))) |
| && (next_trial = try_split (PATTERN (next_trial), next_trial, 0)) |
| && eligible_for_delay (insn, slots_filled, next_trial, flags) |
| && ! can_throw_internal (trial)) |
| { |
| /* See comment in relax_delay_slots about necessity of using |
| next_real_insn here. */ |
| rtx_insn *new_label = next_real_insn (next_trial); |
| |
| if (new_label != 0) |
| new_label = get_label_before (new_label, JUMP_LABEL (trial)); |
| else |
| new_label = find_end_label (simple_return_rtx); |
| |
| if (new_label) |
| { |
| add_to_delay_list (copy_delay_slot_insn (next_trial), |
| &delay_list); |
| slots_filled++; |
| reorg_redirect_jump (as_a <rtx_jump_insn *> (trial), |
| new_label); |
| } |
| } |
| } |
| |
| /* If this is an unconditional jump, then try to get insns from the |
| target of the jump. */ |
| rtx_jump_insn *jump_insn; |
| if ((jump_insn = dyn_cast <rtx_jump_insn *> (insn)) |
| && simplejump_p (jump_insn) |
| && slots_filled != slots_to_fill) |
| fill_slots_from_thread (jump_insn, const_true_rtx, |
| next_active_insn (JUMP_LABEL_AS_INSN (insn)), |
| NULL, 1, 1, own_thread_p (JUMP_LABEL (insn), |
| JUMP_LABEL (insn), 0), |
| slots_to_fill, &slots_filled, &delay_list); |
| |
| if (!delay_list.is_empty ()) |
| unfilled_slots_base[i] |
| = emit_delay_sequence (insn, delay_list, slots_filled); |
| |
| if (slots_to_fill == slots_filled) |
| unfilled_slots_base[i] = 0; |
| |
| note_delay_statistics (slots_filled, 0); |
| } |
| } |
| |
| /* Follow any unconditional jump at LABEL, for the purpose of redirecting JUMP; |
| return the ultimate label reached by any such chain of jumps. |
| Return a suitable return rtx if the chain ultimately leads to a |
| return instruction. |
| If LABEL is not followed by a jump, return LABEL. |
| If the chain loops or we can't find end, return LABEL, |
| since that tells caller to avoid changing the insn. |
| If the returned label is obtained by following a crossing jump, |
| set *CROSSING to true, otherwise set it to false. */ |
| |
| static rtx |
| follow_jumps (rtx label, rtx_insn *jump, bool *crossing) |
| { |
| rtx_insn *insn; |
| rtx_insn *next; |
| int depth; |
| |
| *crossing = false; |
| if (ANY_RETURN_P (label)) |
| return label; |
| |
| rtx_insn *value = as_a <rtx_insn *> (label); |
| |
| for (depth = 0; |
| (depth < 10 |
| && (insn = next_active_insn (value)) != 0 |
| && JUMP_P (insn) |
| && JUMP_LABEL (insn) != NULL_RTX |
| && ((any_uncondjump_p (insn) && onlyjump_p (insn)) |
| || ANY_RETURN_P (PATTERN (insn))) |
| && (next = NEXT_INSN (insn)) |
| && BARRIER_P (next)); |
| depth++) |
| { |
| rtx this_label_or_return = JUMP_LABEL (insn); |
| |
| /* If we have found a cycle, make the insn jump to itself. */ |
| if (this_label_or_return == label) |
| return label; |
| |
| /* Cannot follow returns and cannot look through tablejumps. */ |
| if (ANY_RETURN_P (this_label_or_return)) |
| return this_label_or_return; |
| |
| rtx_insn *this_label = as_a <rtx_insn *> (this_label_or_return); |
| if (NEXT_INSN (this_label) |
| && JUMP_TABLE_DATA_P (NEXT_INSN (this_label))) |
| break; |
| |
| if (!targetm.can_follow_jump (jump, insn)) |
| break; |
| if (!*crossing) |
| *crossing = CROSSING_JUMP_P (jump); |
| value = this_label; |
| } |
| if (depth == 10) |
| return label; |
| return value; |
| } |
| |
| /* Try to find insns to place in delay slots. |
| |
| INSN is the jump needing SLOTS_TO_FILL delay slots. It tests CONDITION |
| or is an unconditional branch if CONDITION is const_true_rtx. |
| *PSLOTS_FILLED is updated with the number of slots that we have filled. |
| |
| THREAD is a flow-of-control, either the insns to be executed if the |
| branch is true or if the branch is false, THREAD_IF_TRUE says which. |
| |
| OPPOSITE_THREAD is the thread in the opposite direction. It is used |
| to see if any potential delay slot insns set things needed there. |
| |
| LIKELY is nonzero if it is extremely likely that the branch will be |
| taken and THREAD_IF_TRUE is set. This is used for the branch at the |
| end of a loop back up to the top. |
| |
| OWN_THREAD and OWN_OPPOSITE_THREAD are true if we are the only user of the |
| thread. I.e., it is the fallthrough code of our jump or the target of the |
| jump when we are the only jump going there. |
| |
| If OWN_THREAD is false, it must be the "true" thread of a jump. In that |
| case, we can only take insns from the head of the thread for our delay |
| slot. We then adjust the jump to point after the insns we have taken. */ |
| |
| static void |
| fill_slots_from_thread (rtx_jump_insn *insn, rtx condition, |
| rtx thread_or_return, rtx opposite_thread, int likely, |
| int thread_if_true, int own_thread, int slots_to_fill, |
| int *pslots_filled, vec<rtx_insn *> *delay_list) |
| { |
| rtx new_thread; |
| struct resources opposite_needed, set, needed; |
| rtx_insn *trial; |
| int lose = 0; |
| int must_annul = 0; |
| int flags; |
| |
| /* Validate our arguments. */ |
| gcc_assert (condition != const_true_rtx || thread_if_true); |
| gcc_assert (own_thread || thread_if_true); |
| |
| flags = get_jump_flags (insn, JUMP_LABEL (insn)); |
| |
| /* If our thread is the end of subroutine, we can't get any delay |
| insns from that. */ |
| if (thread_or_return == NULL_RTX || ANY_RETURN_P (thread_or_return)) |
| return; |
| |
| rtx_insn *thread = as_a <rtx_insn *> (thread_or_return); |
| |
| /* If this is an unconditional branch, nothing is needed at the |
| opposite thread. Otherwise, compute what is needed there. */ |
| if (condition == const_true_rtx) |
| CLEAR_RESOURCE (&opposite_needed); |
| else |
| mark_target_live_regs (get_insns (), opposite_thread, &opposite_needed); |
| |
| /* If the insn at THREAD can be split, do it here to avoid having to |
| update THREAD and NEW_THREAD if it is done in the loop below. Also |
| initialize NEW_THREAD. */ |
| |
| new_thread = thread = try_split (PATTERN (thread), thread, 0); |
| |
| /* Scan insns at THREAD. We are looking for an insn that can be removed |
| from THREAD (it neither sets nor references resources that were set |
| ahead of it and it doesn't set anything needs by the insns ahead of |
| it) and that either can be placed in an annulling insn or aren't |
| needed at OPPOSITE_THREAD. */ |
| |
| CLEAR_RESOURCE (&needed); |
| CLEAR_RESOURCE (&set); |
| |
| /* If we do not own this thread, we must stop as soon as we find |
| something that we can't put in a delay slot, since all we can do |
| is branch into THREAD at a later point. Therefore, labels stop |
| the search if this is not the `true' thread. */ |
| |
| for (trial = thread; |
| ! stop_search_p (trial, ! thread_if_true) && (! lose || own_thread); |
| trial = next_nonnote_insn (trial)) |
| { |
| rtx pat, old_trial; |
| |
| /* If we have passed a label, we no longer own this thread. */ |
| if (LABEL_P (trial)) |
| { |
| own_thread = 0; |
| continue; |
| } |
| |
| pat = PATTERN (trial); |
| if (GET_CODE (pat) == USE || GET_CODE (pat) == CLOBBER) |
| continue; |
| |
| /* If TRIAL conflicts with the insns ahead of it, we lose. Also, |
| don't separate or copy insns that set and use CC0. */ |
| if (! insn_references_resource_p (trial, &set, true) |
| && ! insn_sets_resource_p (trial, &set, true) |
| && ! insn_sets_resource_p (trial, &needed, true) |
| && (!HAVE_cc0 || (! (reg_mentioned_p (cc0_rtx, pat) |
| && (! own_thread || ! sets_cc0_p (pat))))) |
| && ! can_throw_internal (trial)) |
| { |
| rtx_insn *prior_insn; |
| |
| /* If TRIAL is redundant with some insn before INSN, we don't |
| actually need to add it to the delay list; we can merely pretend |
| we did. */ |
| if ((prior_insn = redundant_insn (trial, insn, *delay_list))) |
| { |
| fix_reg_dead_note (prior_insn, insn); |
| if (own_thread) |
| { |
| update_block (trial, thread); |
| if (trial == thread) |
| { |
| thread = next_active_insn (thread); |
| if (new_thread == trial) |
| new_thread = thread; |
| } |
| |
| delete_related_insns (trial); |
| } |
| else |
| { |
| update_reg_unused_notes (prior_insn, trial); |
| new_thread = next_active_insn (trial); |
| } |
| |
| continue; |
| } |
| |
| /* There are two ways we can win: If TRIAL doesn't set anything |
| needed at the opposite thread and can't trap, or if it can |
| go into an annulled delay slot. But we want neither to copy |
| nor to speculate frame-related insns. */ |
| if (!must_annul |
| && ((condition == const_true_rtx |
| && (own_thread || !RTX_FRAME_RELATED_P (trial))) |
| || (! insn_sets_resource_p (trial, &opposite_needed, true) |
| && ! may_trap_or_fault_p (pat) |
| && ! RTX_FRAME_RELATED_P (trial)))) |
| { |
| old_trial = trial; |
| trial = try_split (pat, trial, 0); |
| if (new_thread == old_trial) |
| new_thread = trial; |
| if (thread == old_trial) |
| thread = trial; |
| pat = PATTERN (trial); |
| if (eligible_for_delay (insn, *pslots_filled, trial, flags)) |
| goto winner; |
| } |
| else if (!RTX_FRAME_RELATED_P (trial) |
| && ((ANNUL_IFTRUE_SLOTS && ! thread_if_true) |
| || (ANNUL_IFFALSE_SLOTS && thread_if_true))) |
| { |
| old_trial = trial; |
| trial = try_split (pat, trial, 0); |
| if (new_thread == old_trial) |
| new_thread = trial; |
| if (thread == old_trial) |
| thread = trial; |
| pat = PATTERN (trial); |
| if ((must_annul || delay_list->is_empty ()) && (thread_if_true |
| ? check_annul_list_true_false (0, *delay_list) |
| && eligible_for_annul_false (insn, *pslots_filled, trial, flags) |
| : check_annul_list_true_false (1, *delay_list) |
| && eligible_for_annul_true (insn, *pslots_filled, trial, flags))) |
| { |
| rtx_insn *temp; |
| |
| must_annul = 1; |
| winner: |
| |
| if (HAVE_cc0 && reg_mentioned_p (cc0_rtx, pat)) |
| link_cc0_insns (trial); |
| |
| /* If we own this thread, delete the insn. If this is the |
| destination of a branch, show that a basic block status |
| may have been updated. In any case, mark the new |
| starting point of this thread. */ |
| if (own_thread) |
| { |
| rtx note; |
| |
| update_block (trial, thread); |
| if (trial == thread) |
| { |
| thread = next_active_insn (thread); |
| if (new_thread == trial) |
| new_thread = thread; |
| } |
| |
| /* We are moving this insn, not deleting it. We must |
| temporarily increment the use count on any referenced |
| label lest it be deleted by delete_related_insns. */ |
| for (note = REG_NOTES (trial); |
| note != NULL_RTX; |
| note = XEXP (note, 1)) |
| if (REG_NOTE_KIND (note) == REG_LABEL_OPERAND |
| || REG_NOTE_KIND (note) == REG_LABEL_TARGET) |
| { |
| /* REG_LABEL_OPERAND could be |
| NOTE_INSN_DELETED_LABEL too. */ |
| if (LABEL_P (XEXP (note, 0))) |
| LABEL_NUSES (XEXP (note, 0))++; |
| else |
| gcc_assert (REG_NOTE_KIND (note) |
| == REG_LABEL_OPERAND); |
| } |
| if (jump_to_label_p (trial)) |
| LABEL_NUSES (JUMP_LABEL (trial))++; |
| |
| delete_related_insns (trial); |
| |
| for (note = REG_NOTES (trial); |
| note != NULL_RTX; |
| note = XEXP (note, 1)) |
| if (REG_NOTE_KIND (note) == REG_LABEL_OPERAND |
| || REG_NOTE_KIND (note) == REG_LABEL_TARGET) |
| { |
| /* REG_LABEL_OPERAND could be |
| NOTE_INSN_DELETED_LABEL too. */ |
| if (LABEL_P (XEXP (note, 0))) |
| LABEL_NUSES (XEXP (note, 0))--; |
| else |
| gcc_assert (REG_NOTE_KIND (note) |
| == REG_LABEL_OPERAND); |
| } |
| if (jump_to_label_p (trial)) |
| LABEL_NUSES (JUMP_LABEL (trial))--; |
| } |
| else |
| new_thread = next_active_insn (trial); |
| |
| temp = own_thread ? trial : copy_delay_slot_insn (trial); |
| if (thread_if_true) |
| INSN_FROM_TARGET_P (temp) = 1; |
| |
| add_to_delay_list (temp, delay_list); |
| |
| if (slots_to_fill == ++(*pslots_filled)) |
| { |
| /* Even though we have filled all the slots, we |
| may be branching to a location that has a |
| redundant insn. Skip any if so. */ |
| while (new_thread && ! own_thread |
| && ! insn_sets_resource_p (new_thread, &set, true) |
| && ! insn_sets_resource_p (new_thread, &needed, |
| true) |
| && ! insn_references_resource_p (new_thread, |
| &set, true) |
| && (prior_insn |
| = redundant_insn (new_thread, insn, |
| *delay_list))) |
| { |
| /* We know we do not own the thread, so no need |
| to call update_block and delete_insn. */ |
| fix_reg_dead_note (prior_insn, insn); |
| update_reg_unused_notes (prior_insn, new_thread); |
| new_thread |
| = next_active_insn (as_a<rtx_insn *> (new_thread)); |
| } |
| break; |
| } |
| |
| continue; |
| } |
| } |
| } |
| |
| /* This insn can't go into a delay slot. */ |
| lose = 1; |
| mark_set_resources (trial, &set, 0, MARK_SRC_DEST_CALL); |
| mark_referenced_resources (trial, &needed, true); |
| |
| /* Ensure we don't put insns between the setting of cc and the comparison |
| by moving a setting of cc into an earlier delay slot since these insns |
| could clobber the condition code. */ |
| set.cc = 1; |
| |
| /* If this insn is a register-register copy and the next insn has |
| a use of our destination, change it to use our source. That way, |
| it will become a candidate for our delay slot the next time |
| through this loop. This case occurs commonly in loops that |
| scan a list. |
| |
| We could check for more complex cases than those tested below, |
| but it doesn't seem worth it. It might also be a good idea to try |
| to swap the two insns. That might do better. |
| |
| We can't do this if the next insn modifies our destination, because |
| that would make the replacement into the insn invalid. We also can't |
| do this if it modifies our source, because it might be an earlyclobber |
| operand. This latter test also prevents updating the contents of |
| a PRE_INC. We also can't do this if there's overlap of source and |
| destination. Overlap may happen for larger-than-register-size modes. */ |
| |
| if (NONJUMP_INSN_P (trial) && GET_CODE (pat) == SET |
| && REG_P (SET_SRC (pat)) |
| && REG_P (SET_DEST (pat)) |
| && !reg_overlap_mentioned_p (SET_DEST (pat), SET_SRC (pat))) |
| { |
| rtx_insn *next = next_nonnote_insn (trial); |
| |
| if (next && NONJUMP_INSN_P (next) |
| && GET_CODE (PATTERN (next)) != USE |
| && ! reg_set_p (SET_DEST (pat), next) |
| && ! reg_set_p (SET_SRC (pat), next) |
| && reg_referenced_p (SET_DEST (pat), PATTERN (next)) |
| && ! modified_in_p (SET_DEST (pat), next)) |
| validate_replace_rtx (SET_DEST (pat), SET_SRC (pat), next); |
| } |
| } |
| |
| /* If we stopped on a branch insn that has delay slots, see if we can |
| steal some of the insns in those slots. */ |
| if (trial && NONJUMP_INSN_P (trial) |
| && GET_CODE (PATTERN (trial)) == SEQUENCE |
| && JUMP_P (XVECEXP (PATTERN (trial), 0, 0))) |
| { |
| rtx_sequence *sequence = as_a <rtx_sequence *> (PATTERN (trial)); |
| /* If this is the `true' thread, we will want to follow the jump, |
| so we can only do this if we have taken everything up to here. */ |
| if (thread_if_true && trial == new_thread) |
| { |
| steal_delay_list_from_target (insn, condition, sequence, |
| delay_list, &set, &needed, |
| &opposite_needed, slots_to_fill, |
| pslots_filled, &must_annul, |
| &new_thread); |
| /* If we owned the thread and are told that it branched |
| elsewhere, make sure we own the thread at the new location. */ |
| if (own_thread && trial != new_thread) |
| own_thread = own_thread_p (new_thread, new_thread, 0); |
| } |
| else if (! thread_if_true) |
| steal_delay_list_from_fallthrough (insn, condition, sequence, |
| delay_list, &set, &needed, |
| &opposite_needed, slots_to_fill, |
| pslots_filled, &must_annul); |
| } |
| |
| /* If we haven't found anything for this delay slot and it is very |
| likely that the branch will be taken, see if the insn at our target |
| increments or decrements a register with an increment that does not |
| depend on the destination register. If so, try to place the opposite |
| arithmetic insn after the jump insn and put the arithmetic insn in the |
| delay slot. If we can't do this, return. */ |
| if (delay_list->is_empty () && likely |
| && new_thread && !ANY_RETURN_P (new_thread) |
| && NONJUMP_INSN_P (new_thread) |
| && !RTX_FRAME_RELATED_P (new_thread) |
| && GET_CODE (PATTERN (new_thread)) != ASM_INPUT |
| && asm_noperands (PATTERN (new_thread)) < 0) |
| { |
| rtx pat = PATTERN (new_thread); |
| rtx dest; |
| rtx src; |
| |
| /* We know "new_thread" is an insn due to NONJUMP_INSN_P (new_thread) |
| above. */ |
| trial = as_a <rtx_insn *> (new_thread); |
| pat = PATTERN (trial); |
| |
| if (!NONJUMP_INSN_P (trial) |
| || GET_CODE (pat) != SET |
| || ! eligible_for_delay (insn, 0, trial, flags) |
| || can_throw_internal (trial)) |
| return; |
| |
| dest = SET_DEST (pat), src = SET_SRC (pat); |
| if ((GET_CODE (src) == PLUS || GET_CODE (src) == MINUS) |
| && rtx_equal_p (XEXP (src, 0), dest) |
| && (!FLOAT_MODE_P (GET_MODE (src)) |
| || flag_unsafe_math_optimizations) |
| && ! reg_overlap_mentioned_p (dest, XEXP (src, 1)) |
| && ! side_effects_p (pat)) |
| { |
| rtx other = XEXP (src, 1); |
| rtx new_arith; |
| rtx_insn *ninsn; |
| |
| /* If this is a constant adjustment, use the same code with |
| the negated constant. Otherwise, reverse the sense of the |
| arithmetic. */ |
| if (CONST_INT_P (other)) |
| new_arith = gen_rtx_fmt_ee (GET_CODE (src), GET_MODE (src), dest, |
| negate_rtx (GET_MODE (src), other)); |
| else |
| new_arith = gen_rtx_fmt_ee (GET_CODE (src) == PLUS ? MINUS : PLUS, |
| GET_MODE (src), dest, other); |
| |
| ninsn = emit_insn_after (gen_rtx_SET (dest, new_arith), insn); |
| |
| if (recog_memoized (ninsn) < 0 |
| || (extract_insn (ninsn), |
| !constrain_operands (1, get_preferred_alternatives (ninsn)))) |
| { |
| delete_related_insns (ninsn); |
| return; |
| } |
| |
| if (own_thread) |
| { |
| update_block (trial, thread); |
| if (trial == thread) |
| { |
| thread = next_active_insn (thread); |
| if (new_thread == trial) |
| new_thread = thread; |
| } |
| delete_related_insns (trial); |
| } |
| else |
| new_thread = next_active_insn (trial); |
| |
| ninsn = own_thread ? trial : copy_delay_slot_insn (trial); |
| if (thread_if_true) |
| INSN_FROM_TARGET_P (ninsn) = 1; |
| |
| add_to_delay_list (ninsn, delay_list); |
| (*pslots_filled)++; |
| } |
| } |
| |
| if (!delay_list->is_empty () && must_annul) |
| INSN_ANNULLED_BRANCH_P (insn) = 1; |
| |
| /* If we are to branch into the middle of this thread, find an appropriate |
| label or make a new one if none, and redirect INSN to it. If we hit the |
| end of the function, use the end-of-function label. */ |
| if (new_thread != thread) |
| { |
| rtx label; |
| bool crossing = false; |
| |
| gcc_assert (thread_if_true); |
| |
| if (new_thread && simplejump_or_return_p (new_thread) |
| && redirect_with_delay_list_safe_p (insn, |
| JUMP_LABEL (new_thread), |
| *delay_list)) |
| new_thread = follow_jumps (JUMP_LABEL (new_thread), insn, |
| &crossing); |
| |
| if (ANY_RETURN_P (new_thread)) |
| label = find_end_label (new_thread); |
| else if (LABEL_P (new_thread)) |
| label = new_thread; |
| else |
| label = get_label_before (as_a <rtx_insn *> (new_thread), |
| JUMP_LABEL (insn)); |
| |
| if (label) |
| { |
| reorg_redirect_jump (insn, label); |
| if (crossing) |
| CROSSING_JUMP_P (insn) = 1; |
| } |
| } |
| } |
| |
| /* Make another attempt to find insns to place in delay slots. |
| |
| We previously looked for insns located in front of the delay insn |
| and, for non-jump delay insns, located behind the delay insn. |
| |
| Here only try to schedule jump insns and try to move insns from either |
| the target or the following insns into the delay slot. If annulling is |
| supported, we will be likely to do this. Otherwise, we can do this only |
| if safe. */ |
| |
| static void |
| fill_eager_delay_slots (void) |
| { |
| rtx_insn *insn; |
| int i; |
| int num_unfilled_slots = unfilled_slots_next - unfilled_slots_base; |
| |
| for (i = 0; i < num_unfilled_slots; i++) |
| { |
| rtx condition; |
| rtx target_label, insn_at_target; |
| rtx_insn *fallthrough_insn; |
| auto_vec<rtx_insn *, 5> delay_list; |
| rtx_jump_insn *jump_insn; |
| int own_target; |
| int own_fallthrough; |
| int prediction, slots_to_fill, slots_filled; |
| |
| insn = unfilled_slots_base[i]; |
| if (insn == 0 |
| || insn->deleted () |
| || ! (jump_insn = dyn_cast <rtx_jump_insn *> (insn)) |
| || ! (condjump_p (jump_insn) || condjump_in_parallel_p (jump_insn))) |
| continue; |
| |
| slots_to_fill = num_delay_slots (jump_insn); |
| /* Some machine description have defined instructions to have |
| delay slots only in certain circumstances which may depend on |
| nearby insns (which change due to reorg's actions). |
| |
| For example, the PA port normally has delay slots for unconditional |
| jumps. |
| |
| However, the PA port claims such jumps do not have a delay slot |
| if they are immediate successors of certain CALL_INSNs. This |
| allows the port to favor filling the delay slot of the call with |
| the unconditional jump. */ |
| if (slots_to_fill == 0) |
| continue; |
| |
| slots_filled = 0; |
| target_label = JUMP_LABEL (jump_insn); |
| condition = get_branch_condition (jump_insn, target_label); |
| |
| if (condition == 0) |
| continue; |
| |
| /* Get the next active fallthrough and target insns and see if we own |
| them. Then see whether the branch is likely true. We don't need |
| to do a lot of this for unconditional branches. */ |
| |
| insn_at_target = first_active_target_insn (target_label); |
| own_target = own_thread_p (target_label, target_label, 0); |
| |
| if (condition == const_true_rtx) |
| { |
| own_fallthrough = 0; |
| fallthrough_insn = 0; |
| prediction = 2; |
| } |
| else |
| { |
| fallthrough_insn = next_active_insn (jump_insn); |
| own_fallthrough = own_thread_p (NEXT_INSN (jump_insn), NULL_RTX, 1); |
| prediction = mostly_true_jump (jump_insn); |
| } |
| |
| /* If this insn is expected to branch, first try to get insns from our |
| target, then our fallthrough insns. If it is not expected to branch, |
| try the other order. */ |
| |
| if (prediction > 0) |
| { |
| fill_slots_from_thread (jump_insn, condition, insn_at_target, |
| fallthrough_insn, prediction == 2, 1, |
| own_target, |
| slots_to_fill, &slots_filled, &delay_list); |
| |
| if (delay_list.is_empty () && own_fallthrough) |
| { |
| /* Even though we didn't find anything for delay slots, |
| we might have found a redundant insn which we deleted |
| from the thread that was filled. So we have to recompute |
| the next insn at the target. */ |
| target_label = JUMP_LABEL (jump_insn); |
| insn_at_target = first_active_target_insn (target_label); |
| |
| fill_slots_from_thread (jump_insn, condition, fallthrough_insn, |
| insn_at_target, 0, 0, own_fallthrough, |
| slots_to_fill, &slots_filled, |
| &delay_list); |
| } |
| } |
| else |
| { |
| if (own_fallthrough) |
| fill_slots_from_thread (jump_insn, condition, fallthrough_insn, |
| insn_at_target, 0, 0, own_fallthrough, |
| slots_to_fill, &slots_filled, &delay_list); |
| |
| if (delay_list.is_empty ()) |
| fill_slots_from_thread (jump_insn, condition, insn_at_target, |
| next_active_insn (insn), 0, 1, own_target, |
| slots_to_fill, &slots_filled, &delay_list); |
| } |
| |
| if (!delay_list.is_empty ()) |
| unfilled_slots_base[i] |
| = emit_delay_sequence (jump_insn, delay_list, slots_filled); |
| |
| if (slots_to_fill == slots_filled) |
| unfilled_slots_base[i] = 0; |
| |
| note_delay_statistics (slots_filled, 1); |
| } |
| } |
| |
| static void delete_computation (rtx_insn *insn); |
| |
| /* Recursively delete prior insns that compute the value (used only by INSN |
| which the caller is deleting) stored in the register mentioned by NOTE |
| which is a REG_DEAD note associated with INSN. */ |
| |
| static void |
| delete_prior_computation (rtx note, rtx_insn *insn) |
| { |
| rtx_insn *our_prev; |
| rtx reg = XEXP (note, 0); |
| |
| for (our_prev = prev_nonnote_insn (insn); |
| our_prev && (NONJUMP_INSN_P (our_prev) |
| || CALL_P (our_prev)); |
| our_prev = prev_nonnote_insn (our_prev)) |
| { |
| rtx pat = PATTERN (our_prev); |
| |
| /* If we reach a CALL which is not calling a const function |
| or the callee pops the arguments, then give up. */ |
| if (CALL_P (our_prev) |
| && (! RTL_CONST_CALL_P (our_prev) |
| || GET_CODE (pat) != SET || GET_CODE (SET_SRC (pat)) != CALL)) |
| break; |
| |
| /* If we reach a SEQUENCE, it is too complex to try to |
| do anything with it, so give up. We can be run during |
| and after reorg, so SEQUENCE rtl can legitimately show |
| up here. */ |
| if (GET_CODE (pat) == SEQUENCE) |
| break; |
| |
| if (GET_CODE (pat) == USE |
| && NONJUMP_INSN_P (XEXP (pat, 0))) |
| /* reorg creates USEs that look like this. We leave them |
| alone because reorg needs them for its own purposes. */ |
| break; |
| |
| if (reg_set_p (reg, pat)) |
| { |
| if (side_effects_p (pat) && !CALL_P (our_prev)) |
| break; |
| |
| if (GET_CODE (pat) == PARALLEL) |
| { |
| /* If we find a SET of something else, we can't |
| delete the insn. */ |
| |
| int i; |
| |
| for (i = 0; i < XVECLEN (pat, 0); i++) |
| { |
| rtx part = XVECEXP (pat, 0, i); |
| |
| if (GET_CODE (part) == SET |
| && SET_DEST (part) != reg) |
| break; |
| } |
| |
| if (i == XVECLEN (pat, 0)) |
| delete_computation (our_prev); |
| } |
| else if (GET_CODE (pat) == SET |
| && REG_P (SET_DEST (pat))) |
| { |
| int dest_regno = REGNO (SET_DEST (pat)); |
| int dest_endregno = END_REGNO (SET_DEST (pat)); |
| int regno = REGNO (reg); |
| int endregno = END_REGNO (reg); |
| |
| if (dest_regno >= regno |
| && dest_endregno <= endregno) |
| delete_computation (our_prev); |
| |
| /* We may have a multi-word hard register and some, but not |
| all, of the words of the register are needed in subsequent |
| insns. Write REG_UNUSED notes for those parts that were not |
| needed. */ |
| else if (dest_regno <= regno |
| && dest_endregno >= endregno) |
| { |
| int i; |
| |
| add_reg_note (our_prev, REG_UNUSED, reg); |
| |
| for (i = dest_regno; i < dest_endregno; i++) |
| if (! find_regno_note (our_prev, REG_UNUSED, i)) |
| break; |
| |
| if (i == dest_endregno) |
| delete_computation (our_prev); |
| } |
| } |
| |
| break; |
| } |
| |
| /* If PAT references the register that dies here, it is an |
| additional use. Hence any prior SET isn't dead. However, this |
| insn becomes the new place for the REG_DEAD note. */ |
| if (reg_overlap_mentioned_p (reg, pat)) |
| { |
| XEXP (note, 1) = REG_NOTES (our_prev); |
| REG_NOTES (our_prev) = note; |
| break; |
| } |
| } |
| } |
| |
| /* Delete INSN and recursively delete insns that compute values used only |
| by INSN. This uses the REG_DEAD notes computed during flow analysis. |
| |
| Look at all our REG_DEAD notes. If a previous insn does nothing other |
| than set a register that dies in this insn, we can delete that insn |
| as well. |
| |
| On machines with CC0, if CC0 is used in this insn, we may be able to |
| delete the insn that set it. */ |
| |
| static void |
| delete_computation (rtx_insn *insn) |
| { |
| rtx note, next; |
| |
| if (HAVE_cc0 && reg_referenced_p (cc0_rtx, PATTERN (insn))) |
| { |
| rtx_insn *prev = prev_nonnote_insn (insn); |
| /* We assume that at this stage |
| CC's are always set explicitly |
| and always immediately before the jump that |
| will use them. So if the previous insn |
| exists to set the CC's, delete it |
| (unless it performs auto-increments, etc.). */ |
| if (prev && NONJUMP_INSN_P (prev) |
| && sets_cc0_p (PATTERN (prev))) |
| { |
| if (sets_cc0_p (PATTERN (prev)) > 0 |
| && ! side_effects_p (PATTERN (prev))) |
| delete_computation (prev); |
| else |
| /* Otherwise, show that cc0 won't be used. */ |
| add_reg_note (prev, REG_UNUSED, cc0_rtx); |
| } |
| } |
| |
| for (note = REG_NOTES (insn); note; note = next) |
| { |
| next = XEXP (note, 1); |
| |
| if (REG_NOTE_KIND (note) != REG_DEAD |
| /* Verify that the REG_NOTE is legitimate. */ |
| || !REG_P (XEXP (note, 0))) |
| continue; |
| |
| delete_prior_computation (note, insn); |
| } |
| |
| delete_related_insns (insn); |
| } |
| |
| /* If all INSN does is set the pc, delete it, |
| and delete the insn that set the condition codes for it |
| if that's what the previous thing was. */ |
| |
| static void |
| delete_jump (rtx_insn *insn) |
| { |
| rtx set = single_set (insn); |
| |
| if (set && GET_CODE (SET_DEST (set)) == PC) |
| delete_computation (insn); |
| } |
| |
| static rtx_insn * |
| label_before_next_insn (rtx_insn *x, rtx scan_limit) |
| { |
| rtx_insn *insn = next_active_insn (x); |
| while (insn) |
| { |
| insn = PREV_INSN (insn); |
| if (insn == scan_limit || insn == NULL_RTX) |
| return NULL; |
| if (LABEL_P (insn)) |
| break; |
| } |
| return insn; |
| } |
| |
| /* Return TRUE if there is a NOTE_INSN_SWITCH_TEXT_SECTIONS note in between |
| BEG and END. */ |
| |
| static bool |
| switch_text_sections_between_p (const rtx_insn *beg, const rtx_insn *end) |
| { |
| const rtx_insn *p; |
| for (p = beg; p != end; p = NEXT_INSN (p)) |
| if (NOTE_P (p) && NOTE_KIND (p) == NOTE_INSN_SWITCH_TEXT_SECTIONS) |
| return true; |
| return false; |
| } |
| |
| |
| /* Once we have tried two ways to fill a delay slot, make a pass over the |
| code to try to improve the results and to do such things as more jump |
| threading. */ |
| |
| static void |
| relax_delay_slots (rtx_insn *first) |
| { |
| rtx_insn *insn, *next; |
| rtx_sequence *pat; |
| rtx_insn *delay_insn; |
| rtx target_label; |
| |
| /* Look at every JUMP_INSN and see if we can improve it. */ |
| for (insn = first; insn; insn = next) |
| { |
| rtx_insn *other; |
| bool crossing; |
| |
| next = next_active_insn (insn); |
| |
| /* If this is a jump insn, see if it now jumps to a jump, jumps to |
| the next insn, or jumps to a label that is not the last of a |
| group of consecutive labels. */ |
| if (is_a <rtx_jump_insn *> (insn) |
| && (condjump_p (insn) || condjump_in_parallel_p (insn)) |
| |