| /* Perform instruction reorganizations for delay slot filling. |
| Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, |
| 1999, 2000, 2001, 2002, 2003, 2004 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 2, 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 COPYING. If not, write to the Free |
| Software Foundation, 59 Temple Place - Suite 330, Boston, MA |
| 02111-1307, USA. */ |
| |
| /* 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 and AMD 29000 have 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 Motorola 88000 conditionally exposes its branch delay slot, |
| so code is shorter when it is turned off, but will run faster |
| when useful insns are scheduled there. |
| |
| The IBM ROMP has two forms of branch and call insns, both with and |
| without a delay slot. Much like the 88k, insns not using the delay |
| slot can be shorted (2 bytes vs. 4 bytes), but will run slowed. |
| |
| 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 (or |
| on the m88k, unexpose the branch slot). 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). |
| |
| Not yet implemented: |
| |
| The Acorn Risc Machine can conditionally execute most insns, so |
| it is profitable to move single insns into a position to execute |
| based on the condition code of the previous insn. |
| |
| The HP-PA can conditionally nullify insns, providing a similar |
| effect to the ARM, differing mostly in which insn is "in charge". */ |
| |
| #include "config.h" |
| #include "system.h" |
| #include "coretypes.h" |
| #include "tm.h" |
| #include "toplev.h" |
| #include "rtl.h" |
| #include "tm_p.h" |
| #include "expr.h" |
| #include "function.h" |
| #include "insn-config.h" |
| #include "conditions.h" |
| #include "hard-reg-set.h" |
| #include "basic-block.h" |
| #include "regs.h" |
| #include "recog.h" |
| #include "flags.h" |
| #include "output.h" |
| #include "obstack.h" |
| #include "insn-attr.h" |
| #include "resource.h" |
| #include "except.h" |
| #include "params.h" |
| |
| #ifdef DELAY_SLOTS |
| |
| #ifndef ANNUL_IFTRUE_SLOTS |
| #define eligible_for_annul_true(INSN, SLOTS, TRIAL, FLAGS) 0 |
| #endif |
| #ifndef ANNUL_IFFALSE_SLOTS |
| #define eligible_for_annul_false(INSN, SLOTS, TRIAL, FLAGS) 0 |
| #endif |
| |
| /* 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 *) obstack_base (&unfilled_slots_obstack)) |
| |
| #define unfilled_slots_next \ |
| ((rtx *) obstack_next_free (&unfilled_slots_obstack)) |
| |
| /* Points to the label before the end of the function. */ |
| static rtx end_of_function_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, int); |
| static int resource_conflicts_p (struct resources *, struct resources *); |
| static int insn_references_resource_p (rtx, struct resources *, int); |
| static int insn_sets_resource_p (rtx, struct resources *, int); |
| static rtx find_end_label (void); |
| static rtx emit_delay_sequence (rtx, rtx, int); |
| static rtx add_to_delay_list (rtx, rtx); |
| static rtx delete_from_delay_slot (rtx); |
| static void delete_scheduled_jump (rtx); |
| static void note_delay_statistics (int, int); |
| #if defined(ANNUL_IFFALSE_SLOTS) || defined(ANNUL_IFTRUE_SLOTS) |
| static rtx optimize_skip (rtx); |
| #endif |
| static int get_jump_flags (rtx, rtx); |
| static int rare_destination (rtx); |
| static int mostly_true_jump (rtx, rtx); |
| static rtx get_branch_condition (rtx, rtx); |
| static int condition_dominates_p (rtx, rtx); |
| static int redirect_with_delay_slots_safe_p (rtx, rtx, rtx); |
| static int redirect_with_delay_list_safe_p (rtx, rtx, rtx); |
| static int check_annul_list_true_false (int, rtx); |
| static rtx steal_delay_list_from_target (rtx, rtx, rtx, rtx, |
| struct resources *, |
| struct resources *, |
| struct resources *, |
| int, int *, int *, rtx *); |
| static rtx steal_delay_list_from_fallthrough (rtx, rtx, rtx, rtx, |
| struct resources *, |
| struct resources *, |
| struct resources *, |
| int, int *, int *); |
| static void try_merge_delay_insns (rtx, rtx); |
| static rtx redundant_insn (rtx, rtx, rtx); |
| static int own_thread_p (rtx, rtx, int); |
| static void update_block (rtx, rtx); |
| static int reorg_redirect_jump (rtx, rtx); |
| static void update_reg_dead_notes (rtx, rtx); |
| static void fix_reg_dead_note (rtx, rtx); |
| static void update_reg_unused_notes (rtx, rtx); |
| static void fill_simple_delay_slots (int); |
| static rtx fill_slots_from_thread (rtx, rtx, rtx, rtx, int, int, int, int, |
| int *, rtx); |
| static void fill_eager_delay_slots (void); |
| static void relax_delay_slots (rtx); |
| #ifdef HAVE_return |
| static void make_return_insns (rtx); |
| #endif |
| |
| /* 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, 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: |
| abort (); |
| } |
| } |
| |
| /* 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->unch_memory && res2->unch_memory) |
| || res1->volatil || res2->volatil) |
| return 1; |
| |
| #ifdef HARD_REG_SET |
| return (res1->regs & res2->regs) != HARD_CONST (0); |
| #else |
| { |
| int i; |
| |
| for (i = 0; i < HARD_REG_SET_LONGS; i++) |
| if ((res1->regs[i] & res2->regs[i]) != 0) |
| return 1; |
| return 0; |
| } |
| #endif |
| } |
| |
| /* 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, |
| int 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, |
| int include_delayed_effects) |
| { |
| struct resources insn_sets; |
| |
| CLEAR_RESOURCE (&insn_sets); |
| mark_set_resources (insn, &insn_sets, 0, include_delayed_effects); |
| return resource_conflicts_p (&insn_sets, res); |
| } |
| |
| /* Find a label at the end of the function or before a RETURN. If there is |
| none, make one. */ |
| |
| static rtx |
| find_end_label (void) |
| { |
| rtx insn; |
| |
| /* If we found one previously, return it. */ |
| if (end_of_function_label) |
| return end_of_function_label; |
| |
| /* 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 (GET_CODE (insn) == NOTE |
| || (GET_CODE (insn) == 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 |
| end_of_function_label. */ |
| if (GET_CODE (insn) == BARRIER |
| && GET_CODE (PREV_INSN (insn)) == JUMP_INSN |
| && GET_CODE (PATTERN (PREV_INSN (insn))) == RETURN) |
| { |
| rtx temp = PREV_INSN (PREV_INSN (insn)); |
| end_of_function_label = gen_label_rtx (); |
| LABEL_NUSES (end_of_function_label) = 0; |
| |
| /* Put the label before an USE insns that may proceed the RETURN insn. */ |
| while (GET_CODE (temp) == USE) |
| temp = PREV_INSN (temp); |
| |
| emit_label_after (end_of_function_label, temp); |
| } |
| |
| else if (GET_CODE (insn) == CODE_LABEL) |
| end_of_function_label = insn; |
| else |
| { |
| end_of_function_label = gen_label_rtx (); |
| LABEL_NUSES (end_of_function_label) = 0; |
| /* If the basic block reorder pass moves the return insn to |
| some other place try to locate it again and put our |
| end_of_function_label there. */ |
| while (insn && ! (GET_CODE (insn) == JUMP_INSN |
| && (GET_CODE (PATTERN (insn)) == RETURN))) |
| insn = PREV_INSN (insn); |
| if (insn) |
| { |
| insn = PREV_INSN (insn); |
| |
| /* Put the label before an USE insns that may proceed the |
| RETURN insn. */ |
| while (GET_CODE (insn) == USE) |
| insn = PREV_INSN (insn); |
| |
| emit_label_after (end_of_function_label, insn); |
| } |
| else |
| { |
| /* Otherwise, make a new label and emit a RETURN and BARRIER, |
| if needed. */ |
| emit_label (end_of_function_label); |
| #ifdef HAVE_return |
| if (HAVE_return) |
| { |
| /* The return we make may have delay slots too. */ |
| rtx insn = gen_return (); |
| insn = emit_jump_insn (insn); |
| emit_barrier (); |
| if (num_delay_slots (insn) > 0) |
| obstack_ptr_grow (&unfilled_slots_obstack, insn); |
| } |
| #endif |
| } |
| } |
| |
| /* Show one additional use for this label so it won't go away until |
| we are done. */ |
| ++LABEL_NUSES (end_of_function_label); |
| |
| return end_of_function_label; |
| } |
| |
| /* Put INSN and LIST together in a SEQUENCE rtx of LENGTH, and replace |
| the pattern of INSN with the SEQUENCE. |
| |
| Chain the insns so that NEXT_INSN of each insn in the sequence points to |
| the next and NEXT_INSN of the last insn in the sequence points to |
| the first insn after the sequence. Similarly for PREV_INSN. This makes |
| it easier to scan all insns. |
| |
| Returns the SEQUENCE that replaces INSN. */ |
| |
| static rtx |
| emit_delay_sequence (rtx insn, rtx list, int length) |
| { |
| int i = 1; |
| rtx li; |
| int had_barrier = 0; |
| |
| /* Allocate the rtvec to hold the insns and the SEQUENCE. */ |
| rtvec seqv = rtvec_alloc (length + 1); |
| rtx seq = gen_rtx_SEQUENCE (VOIDmode, seqv); |
| rtx seq_insn = make_insn_raw (seq); |
| rtx first = get_insns (); |
| rtx last = get_last_insn (); |
| |
| /* Make a copy of the insn having delay slots. */ |
| rtx delay_insn = copy_rtx (insn); |
| |
| /* If INSN is followed by a BARRIER, delete the BARRIER since it will only |
| confuse further processing. Update LAST in case it was the last insn. |
| We will put the BARRIER back in later. */ |
| if (NEXT_INSN (insn) && GET_CODE (NEXT_INSN (insn)) == BARRIER) |
| { |
| delete_related_insns (NEXT_INSN (insn)); |
| last = get_last_insn (); |
| had_barrier = 1; |
| } |
| |
| /* Splice our SEQUENCE into the insn stream where INSN used to be. */ |
| NEXT_INSN (seq_insn) = NEXT_INSN (insn); |
| PREV_INSN (seq_insn) = PREV_INSN (insn); |
| |
| if (insn != last) |
| PREV_INSN (NEXT_INSN (seq_insn)) = seq_insn; |
| |
| if (insn != first) |
| NEXT_INSN (PREV_INSN (seq_insn)) = seq_insn; |
| |
| /* Note the calls to set_new_first_and_last_insn must occur after |
| SEQ_INSN has been completely spliced into the insn stream. |
| |
| Otherwise CUR_INSN_UID will get set to an incorrect value because |
| set_new_first_and_last_insn will not find SEQ_INSN in the chain. */ |
| if (insn == last) |
| set_new_first_and_last_insn (first, seq_insn); |
| |
| if (insn == first) |
| set_new_first_and_last_insn (seq_insn, last); |
| |
| /* Build our SEQUENCE and rebuild the insn chain. */ |
| XVECEXP (seq, 0, 0) = delay_insn; |
| INSN_DELETED_P (delay_insn) = 0; |
| PREV_INSN (delay_insn) = PREV_INSN (seq_insn); |
| |
| for (li = list; li; li = XEXP (li, 1), i++) |
| { |
| rtx tem = XEXP (li, 0); |
| rtx note, next; |
| |
| /* Show that this copy of the insn isn't deleted. */ |
| INSN_DELETED_P (tem) = 0; |
| |
| XVECEXP (seq, 0, i) = tem; |
| PREV_INSN (tem) = XVECEXP (seq, 0, i - 1); |
| NEXT_INSN (XVECEXP (seq, 0, i - 1)) = tem; |
| |
| /* SPARC assembler, for instance, emit warning when debug info is output |
| into the delay slot. */ |
| if (INSN_LOCATOR (tem) && !INSN_LOCATOR (seq_insn)) |
| INSN_LOCATOR (seq_insn) = INSN_LOCATOR (tem); |
| INSN_LOCATOR (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: |
| /* Keep the label reference count up to date. */ |
| if (GET_CODE (XEXP (note, 0)) == CODE_LABEL) |
| LABEL_NUSES (XEXP (note, 0)) ++; |
| break; |
| |
| default: |
| break; |
| } |
| } |
| } |
| |
| NEXT_INSN (XVECEXP (seq, 0, length)) = NEXT_INSN (seq_insn); |
| |
| /* If the previous insn is a SEQUENCE, update the NEXT_INSN pointer on the |
| last insn in that SEQUENCE to point to us. Similarly for the first |
| insn in the following insn if it is a SEQUENCE. */ |
| |
| if (PREV_INSN (seq_insn) && GET_CODE (PREV_INSN (seq_insn)) == INSN |
| && GET_CODE (PATTERN (PREV_INSN (seq_insn))) == SEQUENCE) |
| NEXT_INSN (XVECEXP (PATTERN (PREV_INSN (seq_insn)), 0, |
| XVECLEN (PATTERN (PREV_INSN (seq_insn)), 0) - 1)) |
| = seq_insn; |
| |
| if (NEXT_INSN (seq_insn) && GET_CODE (NEXT_INSN (seq_insn)) == INSN |
| && GET_CODE (PATTERN (NEXT_INSN (seq_insn))) == SEQUENCE) |
| PREV_INSN (XVECEXP (PATTERN (NEXT_INSN (seq_insn)), 0, 0)) = seq_insn; |
| |
| /* If there used to be a BARRIER, put it back. */ |
| if (had_barrier) |
| emit_barrier_after (seq_insn); |
| |
| if (i != length + 1) |
| abort (); |
| |
| 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 rtx |
| add_to_delay_list (rtx insn, rtx delay_list) |
| { |
| /* If we have an empty list, just make a new list element. If |
| INSN has its block number recorded, clear it since we may |
| be moving the insn to a new block. */ |
| |
| if (delay_list == 0) |
| { |
| clear_hashed_info_for_insn (insn); |
| return gen_rtx_INSN_LIST (VOIDmode, insn, NULL_RTX); |
| } |
| |
| /* Otherwise this must be an INSN_LIST. Add INSN to the end of the |
| list. */ |
| XEXP (delay_list, 1) = add_to_delay_list (insn, XEXP (delay_list, 1)); |
| |
| return delay_list; |
| } |
| |
| /* 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 |
| delete_from_delay_slot (rtx insn) |
| { |
| rtx trial, seq_insn, seq, prev; |
| rtx delay_list = 0; |
| int i; |
| |
| /* 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 = PATTERN (seq_insn); |
| |
| /* Create a delay list consisting of all the insns other than the one |
| we are deleting (unless we were the only one). */ |
| if (XVECLEN (seq, 0) > 2) |
| for (i = 1; i < XVECLEN (seq, 0); i++) |
| if (XVECEXP (seq, 0, i) != insn) |
| delay_list = add_to_delay_list (XVECEXP (seq, 0, 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 = XVECEXP (seq, 0, 0); |
| delete_related_insns (seq_insn); |
| add_insn_after (trial, prev); |
| |
| if (GET_CODE (trial) == JUMP_INSN |
| && (simplejump_p (trial) || GET_CODE (PATTERN (trial)) == RETURN)) |
| emit_barrier_after (trial); |
| |
| /* If there are any delay insns, remit them. Otherwise clear the |
| annul flag. */ |
| if (delay_list) |
| trial = emit_delay_sequence (trial, delay_list, XVECLEN (seq, 0) - 2); |
| else if (GET_CODE (trial) == JUMP_INSN |
| || GET_CODE (trial) == CALL_INSN |
| || GET_CODE (trial) == INSN) |
| 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) |
| { |
| /* 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. */ |
| |
| #ifdef HAVE_cc0 |
| if (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 (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 trial = previous_insn (insn); |
| if (GET_CODE (trial) == NOTE) |
| 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); |
| } |
| } |
| #endif |
| |
| 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]++; |
| } |
| |
| #if defined(ANNUL_IFFALSE_SLOTS) || defined(ANNUL_IFTRUE_SLOTS) |
| |
| /* 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 rtx |
| optimize_skip (rtx insn) |
| { |
| rtx trial = next_nonnote_insn (insn); |
| rtx next_trial = next_active_insn (trial); |
| rtx delay_list = 0; |
| rtx target_label; |
| int flags; |
| |
| flags = get_jump_flags (insn, JUMP_LABEL (insn)); |
| |
| if (trial == 0 |
| || GET_CODE (trial) != INSN |
| || 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)) |
| || can_throw_internal (trial)) |
| return 0; |
| |
| /* 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 (insn)) |
| && ! (next_trial == 0 && current_function_epilogue_delay_list != 0)) |
| || (next_trial != 0 |
| && GET_CODE (next_trial) == JUMP_INSN |
| && JUMP_LABEL (insn) == JUMP_LABEL (next_trial) |
| && (simplejump_p (next_trial) |
| || GET_CODE (PATTERN (next_trial)) == RETURN))) |
| { |
| 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 0; |
| } |
| |
| delay_list = add_to_delay_list (trial, NULL_RTX); |
| 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 && GET_CODE (next_trial) == JUMP_INSN |
| && (simplejump_p (next_trial) |
| || GET_CODE (PATTERN (next_trial)) == RETURN)) |
| { |
| target_label = JUMP_LABEL (next_trial); |
| if (target_label == 0) |
| target_label = find_end_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; |
| } |
| |
| return delay_list; |
| } |
| #endif |
| |
| /* 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 (rtx 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 zero, then there is no way to determine the branch |
| direction. */ |
| if (GET_CODE (insn) == JUMP_INSN |
| && (condjump_p (insn) || condjump_in_parallel_p (insn)) |
| && INSN_UID (insn) <= max_uid |
| && label != 0 |
| && 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; |
| |
| /* If insn is a conditional branch call mostly_true_jump to get |
| determine the branch prediction. |
| |
| Non conditional branches are predicted as very likely taken. */ |
| if (GET_CODE (insn) == JUMP_INSN |
| && (condjump_p (insn) || condjump_in_parallel_p (insn))) |
| { |
| int prediction; |
| |
| prediction = mostly_true_jump (insn, get_branch_condition (insn, label)); |
| switch (prediction) |
| { |
| case 2: |
| flags |= (ATTR_FLAG_very_likely | ATTR_FLAG_likely); |
| break; |
| case 1: |
| flags |= ATTR_FLAG_likely; |
| break; |
| case 0: |
| flags |= ATTR_FLAG_unlikely; |
| break; |
| case -1: |
| flags |= (ATTR_FLAG_very_unlikely | ATTR_FLAG_unlikely); |
| break; |
| |
| default: |
| abort (); |
| } |
| } |
| else |
| flags |= (ATTR_FLAG_very_likely | ATTR_FLAG_likely); |
| |
| return flags; |
| } |
| |
| /* Return 1 if INSN is a destination that will be branched to rarely (the |
| return point of a function); return 2 if DEST will be branched to very |
| rarely (a call to a function that doesn't return). Otherwise, |
| return 0. */ |
| |
| static int |
| rare_destination (rtx insn) |
| { |
| int jump_count = 0; |
| rtx next; |
| |
| for (; insn; insn = next) |
| { |
| if (GET_CODE (insn) == INSN && GET_CODE (PATTERN (insn)) == SEQUENCE) |
| insn = XVECEXP (PATTERN (insn), 0, 0); |
| |
| next = NEXT_INSN (insn); |
| |
| switch (GET_CODE (insn)) |
| { |
| case CODE_LABEL: |
| return 0; |
| case BARRIER: |
| /* A BARRIER can either be after a JUMP_INSN or a CALL_INSN. We |
| don't scan past JUMP_INSNs, so any barrier we find here must |
| have been after a CALL_INSN and hence mean the call doesn't |
| return. */ |
| return 2; |
| case JUMP_INSN: |
| if (GET_CODE (PATTERN (insn)) == RETURN) |
| return 1; |
| else if (simplejump_p (insn) |
| && jump_count++ < 10) |
| next = JUMP_LABEL (insn); |
| else |
| return 0; |
| |
| default: |
| break; |
| } |
| } |
| |
| /* If we got here it means we hit the end of the function. So this |
| is an unlikely destination. */ |
| |
| return 1; |
| } |
| |
| /* 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. |
| |
| CONDITION, if nonzero, is the condition that JUMP_INSN is testing. */ |
| |
| static int |
| mostly_true_jump (rtx jump_insn, rtx condition) |
| { |
| rtx target_label = JUMP_LABEL (jump_insn); |
| rtx insn, note; |
| int rare_dest = rare_destination (target_label); |
| int rare_fallthrough = rare_destination (NEXT_INSN (jump_insn)); |
| |
| /* If branch probabilities are available, then use that number since it |
| always gives a correct answer. */ |
| note = find_reg_note (jump_insn, REG_BR_PROB, 0); |
| if (note) |
| { |
| int prob = INTVAL (XEXP (note, 0)); |
| |
| 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; |
| } |
| |
| /* ??? Ought to use estimate_probability instead. */ |
| |
| /* If this is a branch outside a loop, it is highly unlikely. */ |
| if (GET_CODE (PATTERN (jump_insn)) == SET |
| && GET_CODE (SET_SRC (PATTERN (jump_insn))) == IF_THEN_ELSE |
| && ((GET_CODE (XEXP (SET_SRC (PATTERN (jump_insn)), 1)) == LABEL_REF |
| && LABEL_OUTSIDE_LOOP_P (XEXP (SET_SRC (PATTERN (jump_insn)), 1))) |
| || (GET_CODE (XEXP (SET_SRC (PATTERN (jump_insn)), 2)) == LABEL_REF |
| && LABEL_OUTSIDE_LOOP_P (XEXP (SET_SRC (PATTERN (jump_insn)), 2))))) |
| return -1; |
| |
| if (target_label) |
| { |
| /* If this is the test of a loop, it is very likely true. We scan |
| backwards from the target label. If we find a NOTE_INSN_LOOP_BEG |
| before the next real insn, we assume the branch is to the top of |
| the loop. */ |
| for (insn = PREV_INSN (target_label); |
| insn && GET_CODE (insn) == NOTE; |
| insn = PREV_INSN (insn)) |
| if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG) |
| return 2; |
| |
| /* If this is a jump to the test of a loop, it is likely true. We scan |
| forwards from the target label. If we find a NOTE_INSN_LOOP_VTOP |
| before the next real insn, we assume the branch is to the loop branch |
| test. */ |
| for (insn = NEXT_INSN (target_label); |
| insn && GET_CODE (insn) == NOTE; |
| insn = PREV_INSN (insn)) |
| if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_VTOP) |
| return 1; |
| } |
| |
| /* Look at the relative rarities of the fallthrough and destination. If |
| they differ, we can predict the branch that way. */ |
| |
| switch (rare_fallthrough - rare_dest) |
| { |
| case -2: |
| return -1; |
| case -1: |
| return 0; |
| case 0: |
| break; |
| case 1: |
| return 1; |
| case 2: |
| return 2; |
| } |
| |
| /* If we couldn't figure out what this jump was, assume it won't be |
| taken. This should be rare. */ |
| if (condition == 0) |
| return 0; |
| |
| /* EQ tests are usually false and NE tests are usually true. Also, |
| most quantities are positive, so we can make the appropriate guesses |
| about signed comparisons against zero. */ |
| switch (GET_CODE (condition)) |
| { |
| case CONST_INT: |
| /* Unconditional branch. */ |
| return 1; |
| case EQ: |
| return 0; |
| case NE: |
| return 1; |
| case LE: |
| case LT: |
| if (XEXP (condition, 1) == const0_rtx) |
| return 0; |
| break; |
| case GE: |
| case GT: |
| if (XEXP (condition, 1) == const0_rtx) |
| return 1; |
| break; |
| |
| default: |
| break; |
| } |
| |
| /* Predict backward branches usually take, forward branches usually not. If |
| we don't know whether this is forward or backward, assume the branch |
| will be taken, since most are. */ |
| return (target_label == 0 || INSN_UID (jump_insn) > max_uid |
| || INSN_UID (target_label) > max_uid |
| || (uid_to_ruid[INSN_UID (jump_insn)] |
| > uid_to_ruid[INSN_UID (target_label)])); |
| } |
| |
| /* 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 (rtx insn, rtx target) |
| { |
| rtx pat = PATTERN (insn); |
| rtx src; |
| |
| if (condjump_in_parallel_p (insn)) |
| pat = XVECEXP (pat, 0, 0); |
| |
| if (GET_CODE (pat) == RETURN) |
| return target == 0 ? const_true_rtx : 0; |
| |
| else if (GET_CODE (pat) != SET || SET_DEST (pat) != pc_rtx) |
| return 0; |
| |
| src = SET_SRC (pat); |
| if (GET_CODE (src) == LABEL_REF && XEXP (src, 0) == target) |
| return const_true_rtx; |
| |
| else if (GET_CODE (src) == IF_THEN_ELSE |
| && ((target == 0 && GET_CODE (XEXP (src, 1)) == RETURN) |
| || (GET_CODE (XEXP (src, 1)) == LABEL_REF |
| && XEXP (XEXP (src, 1), 0) == target)) |
| && XEXP (src, 2) == pc_rtx) |
| return XEXP (src, 0); |
| |
| else if (GET_CODE (src) == IF_THEN_ELSE |
| && ((target == 0 && GET_CODE (XEXP (src, 2)) == RETURN) |
| || (GET_CODE (XEXP (src, 2)) == LABEL_REF |
| && XEXP (XEXP (src, 2), 0) == target)) |
| && XEXP (src, 1) == pc_rtx) |
| { |
| 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, rtx 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 jump, rtx newlabel, rtx seq) |
| { |
| int flags, i; |
| rtx pat = 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 < XVECLEN (pat, 0); i++) |
| if (! ( |
| #ifdef ANNUL_IFFALSE_SLOTS |
| (INSN_ANNULLED_BRANCH_P (jump) |
| && INSN_FROM_TARGET_P (XVECEXP (pat, 0, i))) |
| ? eligible_for_annul_false (jump, i - 1, |
| XVECEXP (pat, 0, i), flags) : |
| #endif |
| #ifdef ANNUL_IFTRUE_SLOTS |
| (INSN_ANNULLED_BRANCH_P (jump) |
| && ! INSN_FROM_TARGET_P (XVECEXP (pat, 0, i))) |
| ? eligible_for_annul_true (jump, i - 1, |
| XVECEXP (pat, 0, i), flags) : |
| #endif |
| eligible_for_delay (jump, i - 1, XVECEXP (pat, 0, i), flags))) |
| break; |
| |
| return (i == XVECLEN (pat, 0)); |
| } |
| |
| /* 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 jump, rtx newlabel, rtx delay_list) |
| { |
| int flags, i; |
| rtx li; |
| |
| /* Make sure all the insns in DELAY_LIST would still be |
| valid after threading the jump. If they are still |
| valid, then return nonzero. */ |
| |
| flags = get_jump_flags (jump, newlabel); |
| for (li = delay_list, i = 0; li; li = XEXP (li, 1), i++) |
| if (! ( |
| #ifdef ANNUL_IFFALSE_SLOTS |
| (INSN_ANNULLED_BRANCH_P (jump) |
| && INSN_FROM_TARGET_P (XEXP (li, 0))) |
| ? eligible_for_annul_false (jump, i, XEXP (li, 0), flags) : |
| #endif |
| #ifdef ANNUL_IFTRUE_SLOTS |
| (INSN_ANNULLED_BRANCH_P (jump) |
| && ! INSN_FROM_TARGET_P (XEXP (li, 0))) |
| ? eligible_for_annul_true (jump, i, XEXP (li, 0), flags) : |
| #endif |
| eligible_for_delay (jump, i, XEXP (li, 0), flags))) |
| break; |
| |
| return (li == NULL); |
| } |
| |
| /* 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, rtx delay_list) |
| { |
| rtx temp; |
| |
| if (delay_list) |
| { |
| for (temp = delay_list; temp; temp = XEXP (temp, 1)) |
| { |
| rtx trial = XEXP (temp, 0); |
| |
| 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 rtx |
| steal_delay_list_from_target (rtx insn, rtx condition, rtx seq, |
| rtx delay_list, struct resources *sets, |
| struct resources *needed, |
| struct resources *other_needed, |
| int slots_to_fill, int *pslots_filled, |
| int *pannul_p, rtx *pnew_thread) |
| { |
| rtx temp; |
| int slots_remaining = slots_to_fill - *pslots_filled; |
| int total_slots_filled = *pslots_filled; |
| rtx new_delay_list = 0; |
| int must_annul = *pannul_p; |
| int used_annul = 0; |
| int i; |
| struct resources cc_set; |
| |
| /* 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); |
| for (temp = delay_list; temp; temp = XEXP (temp, 1)) |
| { |
| rtx trial = XEXP (temp, 0); |
| |
| mark_set_resources (trial, &cc_set, 0, MARK_SRC_DEST_CALL); |
| if (insn_references_resource_p (XVECEXP (seq , 0, 0), &cc_set, 0)) |
| return delay_list; |
| } |
| |
| if (XVECLEN (seq, 0) - 1 > slots_remaining |
| || ! condition_dominates_p (condition, XVECEXP (seq, 0, 0)) |
| || ! single_set (XVECEXP (seq, 0, 0))) |
| return delay_list; |
| |
| #ifdef MD_CAN_REDIRECT_BRANCH |
| /* 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 (! MD_CAN_REDIRECT_BRANCH (insn, XVECEXP (seq, 0, 0))) |
| return delay_list; |
| #endif |
| |
| for (i = 1; i < XVECLEN (seq, 0); i++) |
| { |
| rtx trial = XVECEXP (seq, 0, i); |
| int flags; |
| |
| if (insn_references_resource_p (trial, sets, 0) |
| || insn_sets_resource_p (trial, needed, 0) |
| || insn_sets_resource_p (trial, sets, 0) |
| #ifdef HAVE_cc0 |
| /* If TRIAL sets CC0, we can't copy it, so we can't steal this |
| delay list. */ |
| || find_reg_note (trial, REG_CC_USER, NULL_RTX) |
| #endif |
| /* If TRIAL is from the fallthrough code of an annulled branch insn |
| in SEQ, we cannot use it. */ |
| || (INSN_ANNULLED_BRANCH_P (XVECEXP (seq, 0, 0)) |
| && ! INSN_FROM_TARGET_P (trial))) |
| return delay_list; |
| |
| /* If this insn was already done (usually in a previous delay slot), |
| pretend we put it in our delay slot. */ |
| if (redundant_insn (trial, insn, new_delay_list)) |
| 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 (XVECEXP (seq, 0, 0))); |
| |
| if (! must_annul |
| && ((condition == const_true_rtx |
| || (! insn_sets_resource_p (trial, other_needed, 0) |
| && ! may_trap_p (PATTERN (trial))))) |
| ? eligible_for_delay (insn, total_slots_filled, trial, flags) |
| : (must_annul || (delay_list == NULL && new_delay_list == NULL)) |
| && (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) |
| used_annul = 1; |
| temp = copy_rtx (trial); |
| INSN_FROM_TARGET_P (temp) = 1; |
| new_delay_list = add_to_delay_list (temp, new_delay_list); |
| total_slots_filled++; |
| |
| if (--slots_remaining == 0) |
| break; |
| } |
| else |
| return delay_list; |
| } |
| |
| /* Show the place to which we will be branching. */ |
| *pnew_thread = next_active_insn (JUMP_LABEL (XVECEXP (seq, 0, 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; |
| |
| if (delay_list == 0) |
| return new_delay_list; |
| |
| for (temp = new_delay_list; temp; temp = XEXP (temp, 1)) |
| delay_list = add_to_delay_list (XEXP (temp, 0), delay_list); |
| |
| return 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 rtx |
| steal_delay_list_from_fallthrough (rtx insn, rtx condition, rtx seq, |
| rtx 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_p (XVECEXP (seq, 0, 0)) |
| && GET_CODE (PATTERN (XVECEXP (seq, 0, 0))) != RETURN) |
| return delay_list; |
| |
| for (i = 1; i < XVECLEN (seq, 0); i++) |
| { |
| rtx trial = XVECEXP (seq, 0, i); |
| |
| /* If TRIAL sets CC0, stealing it will move it too far from the use |
| of CC0. */ |
| if (insn_references_resource_p (trial, sets, 0) |
| || insn_sets_resource_p (trial, needed, 0) |
| || insn_sets_resource_p (trial, sets, 0) |
| #ifdef HAVE_cc0 |
| || sets_cc0_p (PATTERN (trial)) |
| #endif |
| ) |
| |
| break; |
| |
| /* If this insn was already done, we don't need it. */ |
| if (redundant_insn (trial, insn, delay_list)) |
| { |
| delete_from_delay_slot (trial); |
| continue; |
| } |
| |
| if (! must_annul |
| && ((condition == const_true_rtx |
| || (! insn_sets_resource_p (trial, other_needed, 0) |
| && ! may_trap_p (PATTERN (trial))))) |
| ? eligible_for_delay (insn, *pslots_filled, trial, flags) |
| : (must_annul || delay_list == NULL) && (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); |
| delay_list = add_to_delay_list (trial, delay_list); |
| |
| if (++(*pslots_filled) == slots_to_fill) |
| break; |
| } |
| else |
| break; |
| } |
| |
| if (used_annul) |
| *pannul_p = 1; |
| return delay_list; |
| } |
| |
| /* 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, rtx thread) |
| { |
| rtx trial, next_trial; |
| rtx delay_insn = XVECEXP (PATTERN (insn), 0, 0); |
| int annul_p = 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; |
| rtx merged_insns = 0; |
| int i; |
| 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 (i = 1 ; i < num_slots; i++) |
| if (XVECEXP (PATTERN (insn), 0, i)) |
| mark_referenced_resources (XVECEXP (PATTERN (insn), 0, i), &needed, 1); |
| |
| 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 (GET_CODE (trial) == INSN |
| && (GET_CODE (pat) == USE || GET_CODE (pat) == CLOBBER)) |
| continue; |
| |
| if (GET_CODE (next_to_match) == GET_CODE (trial) |
| #ifdef HAVE_cc0 |
| /* We can't share an insn that sets cc0. */ |
| && ! sets_cc0_p (pat) |
| #endif |
| && ! insn_references_resource_p (trial, &set, 1) |
| && ! insn_sets_resource_p (trial, &set, 1) |
| && ! insn_sets_resource_p (trial, &needed, 1) |
| && (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 = gen_rtx_INSN_LIST (VOIDmode, trial, merged_insns); |
| |
| 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, 1); |
| } |
| |
| /* 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 && GET_CODE (trial) == INSN |
| && GET_CODE (PATTERN (trial)) == SEQUENCE |
| && ! INSN_ANNULLED_BRANCH_P (XVECEXP (PATTERN (trial), 0, 0))) |
| { |
| rtx pat = 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, 1); |
| |
| for (i = 1; i < XVECLEN (pat, 0); i++) |
| { |
| rtx dtrial = XVECEXP (pat, 0, i); |
| |
| if (! insn_references_resource_p (dtrial, &set, 1) |
| && ! insn_sets_resource_p (dtrial, &set, 1) |
| && ! insn_sets_resource_p (dtrial, &needed, 1) |
| #ifdef HAVE_cc0 |
| && ! sets_cc0_p (PATTERN (dtrial)) |
| #endif |
| && rtx_equal_p (PATTERN (next_to_match), PATTERN (dtrial)) |
| && eligible_for_delay (delay_insn, slot_number - 1, dtrial, flags)) |
| { |
| if (! annul_p) |
| { |
| rtx new; |
| |
| update_block (dtrial, thread); |
| new = delete_from_delay_slot (dtrial); |
| if (INSN_DELETED_P (thread)) |
| thread = new; |
| INSN_FROM_TARGET_P (next_to_match) = 0; |
| } |
| else |
| merged_insns = gen_rtx_INSN_LIST (SImode, dtrial, |
| merged_insns); |
| |
| 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, 1); |
| } |
| } |
| } |
| |
| /* 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) |
| { |
| for (; merged_insns; merged_insns = XEXP (merged_insns, 1)) |
| { |
| if (GET_MODE (merged_insns) == SImode) |
| { |
| rtx new; |
| |
| update_block (XEXP (merged_insns, 0), thread); |
| new = delete_from_delay_slot (XEXP (merged_insns, 0)); |
| if (INSN_DELETED_P (thread)) |
| thread = new; |
| } |
| else |
| { |
| update_block (XEXP (merged_insns, 0), thread); |
| delete_related_insns (XEXP (merged_insns, 0)); |
| } |
| } |
| |
| INSN_ANNULLED_BRANCH_P (delay_insn) = 0; |
| |
| for (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 |
| redundant_insn (rtx insn, rtx target, rtx delay_list) |
| { |
| rtx target_main = target; |
| rtx ipat = PATTERN (insn); |
| rtx trial, 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), --insns_to_search) |
| { |
| if (GET_CODE (trial) == CODE_LABEL) |
| return 0; |
| |
| if (! INSN_P (trial)) |
| continue; |
| |
| pat = PATTERN (trial); |
| if (GET_CODE (pat) == USE || GET_CODE (pat) == CLOBBER) |
| continue; |
| |
| if (GET_CODE (pat) == SEQUENCE) |
| { |
| /* Stop for a CALL and its delay slots because it is difficult to |
| track its resource needs correctly. */ |
| if (GET_CODE (XVECEXP (pat, 0, 0)) == CALL_INSN) |
| 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. */ |
| |
| #ifdef INSN_SETS_ARE_DELAYED |
| if (INSN_SETS_ARE_DELAYED (XVECEXP (pat, 0, 0))) |
| return 0; |
| #endif |
| |
| #ifdef INSN_REFERENCES_ARE_DELAYED |
| if (INSN_REFERENCES_ARE_DELAYED (XVECEXP (pat, 0, 0))) |
| return 0; |
| #endif |
| |
| /* See if any of the insns in the delay slot match, updating |
| resource requirements as we go. */ |
| for (i = XVECLEN (pat, 0) - 1; i > 0; i--) |
| if (GET_CODE (XVECEXP (pat, 0, i)) == GET_CODE (insn) |
| && rtx_equal_p (PATTERN (XVECEXP (pat, 0, i)), ipat) |
| && ! find_reg_note (XVECEXP (pat, 0, 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, 1); |
| |
| /* If TARGET is a SEQUENCE, get the main insn. */ |
| if (GET_CODE (target) == INSN && GET_CODE (PATTERN (target)) == SEQUENCE) |
| target_main = XVECEXP (PATTERN (target), 0, 0); |
| |
| if (resource_conflicts_p (&needed, &set) |
| #ifdef HAVE_cc0 |
| || reg_mentioned_p (cc0_rtx, ipat) |
| #endif |
| /* The insn requiring the delay may not set anything needed or set by |
| INSN. */ |
| || insn_sets_resource_p (target_main, &needed, 1) |
| || insn_sets_resource_p (target_main, &set, 1)) |
| return 0; |
| |
| /* Insns we pass may not set either NEEDED or SET, so merge them for |
| simpler tests. */ |
| needed.memory |= set.memory; |
| needed.unch_memory |= set.unch_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. */ |
| |
| while (delay_list) |
| { |
| if (insn_sets_resource_p (XEXP (delay_list, 0), &needed, 1)) |
| return 0; |
| delay_list = XEXP (delay_list, 1); |
| } |
| |
| if (GET_CODE (target) == INSN && 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, 1)) |
| 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 && GET_CODE (trial) != CODE_LABEL && insns_to_search > 0; |
| trial = PREV_INSN (trial), --insns_to_search) |
| { |
| if (GET_CODE (trial) != INSN && GET_CODE (trial) != CALL_INSN |
| && GET_CODE (trial) != JUMP_INSN) |
| continue; |
| |
| pat = PATTERN (trial); |
| if (GET_CODE (pat) == USE || GET_CODE (pat) == CLOBBER) |
| continue; |
| |
| if (GET_CODE (pat) == SEQUENCE) |
| { |
| /* If this is a CALL_INSN and its delay slots, it is hard to track |
| the resource needs properly, so give up. */ |
| if (GET_CODE (XVECEXP (pat, 0, 0)) == CALL_INSN) |
| 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. */ |
| |
| #ifdef INSN_SETS_ARE_DELAYED |
| if (INSN_SETS_ARE_DELAYED (XVECEXP (pat, 0, 0))) |
| return 0; |
| #endif |
| |
| #ifdef INSN_REFERENCES_ARE_DELAYED |
| if (INSN_REFERENCES_ARE_DELAYED (XVECEXP (pat, 0, 0))) |
| return 0; |
| #endif |
| |
| /* See if any of the insns in the delay slot match, updating |
| resource requirements as we go. */ |
| for (i = XVECLEN (pat, 0) - 1; i > 0; i--) |
| { |
| rtx candidate = XVECEXP (pat, 0, 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) |
| && ! (INSN_ANNULLED_BRANCH_P (XVECEXP (pat, 0, 0)) |
| && 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 ((! INSN_ANNULLED_BRANCH_P (XVECEXP (pat, 0, 0)) |
| || ! INSN_FROM_TARGET_P (candidate)) |
| && insn_sets_resource_p (candidate, &needed, 1)) |
| return 0; |
| } |
| |
| /* If the insn requiring the delay slot conflicts with INSN, we |
| must stop. */ |
| if (insn_sets_resource_p (XVECEXP (pat, 0, 0), &needed, 1)) |
| 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, 1)) |
| 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 active_insn; |
| rtx insn; |
| |
| /* We don't own the function end. */ |
| if (thread == 0) |
| return 0; |
| |
| /* Get the first active insn, or THREAD, if it is an active insn. */ |
| active_insn = next_active_insn (PREV_INSN (thread)); |
| |
| for (insn = thread; insn != active_insn; insn = NEXT_INSN (insn)) |
| if (GET_CODE (insn) == CODE_LABEL |
| && (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 == 0 || GET_CODE (insn) != BARRIER; |
| insn = prev_nonnote_insn (insn)) |
| if (insn == 0 |
| || GET_CODE (insn) == CODE_LABEL |
| || (GET_CODE (insn) == 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 when |
| reorg finishes. |
| |
| 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, rtx where) |
| { |
| /* Ignore if this was in a delay slot and it came from the target of |
| a branch. */ |
| if (INSN_FROM_TARGET_P (insn)) |
| return; |
| |
| 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, 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 an 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, rtx delayed_insn) |
| { |
| rtx p, link, next; |
| |
| 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 |
| || GET_CODE (XEXP (link, 0)) != REG) |
| 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 start_insn, rtx stop_insn) |
| { |
| rtx p, link, next; |
| |
| 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 |
| || GET_CODE (XEXP (link, 0)) != REG) |
| 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, 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 |
| || GET_CODE (XEXP (link, 0)) != REG) |
| continue; |
| |
| if (! find_regno_note (redundant_insn, REG_UNUSED, |
| REGNO (XEXP (link, 0)))) |
| remove_note (insn, link); |
| } |
| } |
| |
| /* 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, pat, trial, next_trial; |
| int i; |
| int num_unfilled_slots = unfilled_slots_next - unfilled_slots_base; |
| struct resources needed, set; |
| int slots_to_fill, slots_filled; |
| rtx 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_P (insn) |
| || (GET_CODE (insn) == INSN |
| && GET_CODE (PATTERN (insn)) == SEQUENCE) |
| || (GET_CODE (insn) == JUMP_INSN && non_jumps_p) |
| || (GET_CODE (insn) != JUMP_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 = 0; |
| |
| if (GET_CODE (insn) == JUMP_INSN) |
| flags = get_jump_flags (insn, JUMP_LABEL (insn)); |
| else |
| flags = get_jump_flags (insn, NULL_RTX); |
| |
| if ((trial = next_active_insn (insn)) |
| && GET_CODE (trial) == JUMP_INSN |
| && simplejump_p (trial) |
| && eligible_for_delay (insn, slots_filled, trial, flags) |
| && no_labels_between_p (insn, trial) |
| && ! can_throw_internal (trial)) |
| { |
| rtx *tmp; |
| slots_filled++; |
| delay_list = 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 next = NEXT_INSN (trial); |
| rtx prev = PREV_INSN (trial); |
| if (prev) |
| NEXT_INSN (prev) = next; |
| if (next) |
| 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) |
| { |
| CLEAR_RESOURCE (&needed); |
| CLEAR_RESOURCE (&set); |
| mark_set_resources (insn, &set, 0, MARK_SRC_DEST); |
| mark_referenced_resources (insn, &needed, 0); |
| |
| 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); |
| |
| /* USE and CLOBBER at this level was just for flow; ignore it. */ |
| 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, 1) |
| && ! insn_sets_resource_p (trial, &set, 1) |
| && ! insn_sets_resource_p (trial, &needed, 1) |
| #ifdef HAVE_cc0 |
| /* Can't separate set of cc0 from its use. */ |
| && ! (reg_mentioned_p (cc0_rtx, pat) && ! sets_cc0_p (pat)) |
| #endif |
| && ! 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 = gen_rtx_INSN_LIST (VOIDmode, |
| trial, delay_list); |
| 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); |
| mark_referenced_resources (trial, &needed, 1); |
| } |
| } |
| |
| /* If all needed slots haven't been filled, we come here. */ |
| |
| /* Try to optimize case of jumping around a single insn. */ |
| #if defined(ANNUL_IFFALSE_SLOTS) || defined(ANNUL_IFTRUE_SLOTS) |
| if (slots_filled != slots_to_fill |
| && delay_list == 0 |
| && GET_CODE (insn) == JUMP_INSN |
| && (condjump_p (insn) || condjump_in_parallel_p (insn))) |
| { |
| delay_list = optimize_skip (insn); |
| if (delay_list) |
| slots_filled += 1; |
| } |
| #endif |
| |
| /* 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) |
| && (GET_CODE (insn) != JUMP_INSN |
| || ((condjump_p (insn) || condjump_in_parallel_p (insn)) |
| && ! simplejump_p (insn) |
| && JUMP_LABEL (insn) != 0))) |
| { |
| /* Invariant: If insn is a JUMP_INSN, the insn's jump |
| label. Otherwise, zero. */ |
| rtx target = 0; |
| int maybe_never = 0; |
| rtx pat, trial_delay; |
| |
| CLEAR_RESOURCE (&needed); |
| CLEAR_RESOURCE (&set); |
| |
| if (GET_CODE (insn) == CALL_INSN) |
| { |
| mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL); |
| mark_referenced_resources (insn, &needed, 1); |
| maybe_never = 1; |
| } |
| else |
| { |
| mark_set_resources (insn, &set, 0, MARK_SRC_DEST_CALL); |
| mark_referenced_resources (insn, &needed, 1); |
| if (GET_CODE (insn) == JUMP_INSN) |
| target = JUMP_LABEL (insn); |
| } |
| |
| if (target == 0) |
| for (trial = next_nonnote_insn (insn); trial; trial = next_trial) |
| { |
| next_trial = next_nonnote_insn (trial); |
| |
| if (GET_CODE (trial) == CODE_LABEL |
| || GET_CODE (trial) == BARRIER) |
| break; |
| |
| /* We must have an INSN, JUMP_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 an unconditional jump. */ |
| if (GET_CODE (trial_delay) == JUMP_INSN) |
| break; |
| |
| /* See if we have a resource problem before we try to |
| split. */ |
| if (GET_CODE (pat) != SEQUENCE |
| && ! insn_references_resource_p (trial, &set, 1) |
| && ! insn_sets_resource_p (trial, &set, 1) |
| && ! insn_sets_resource_p (trial, &needed, 1) |
| #ifdef HAVE_cc0 |
| && ! (reg_mentioned_p (cc0_rtx, pat) && ! sets_cc0_p (pat)) |
| #endif |
| && ! (maybe_never && may_trap_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); |
| delay_list = add_to_delay_list (trial, delay_list); |
| |
| #ifdef HAVE_cc0 |
| if (reg_mentioned_p (cc0_rtx, pat)) |
| link_cc0_insns (trial); |
| #endif |
| |
| 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, 1); |
| |
| /* 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 or jump, we might not get here. */ |
| if (GET_CODE (trial_delay) == CALL_INSN |
| || GET_CODE (trial_delay) == JUMP_INSN) |
| 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 |
| && GET_CODE (trial) == JUMP_INSN |
| && simplejump_p (trial) |
| && (target == 0 || JUMP_LABEL (trial) == target) |
| && (next_trial = next_active_insn (JUMP_LABEL (trial))) != 0 |
| && ! (GET_CODE (next_trial) == INSN |
| && GET_CODE (PATTERN (next_trial)) == SEQUENCE) |
| && GET_CODE (next_trial) != JUMP_INSN |
| && ! insn_references_resource_p (next_trial, &set, 1) |
| && ! insn_sets_resource_p (next_trial, &set, 1) |
| && ! insn_sets_resource_p (next_trial, &needed, 1) |
| #ifdef HAVE_cc0 |
| && ! reg_mentioned_p (cc0_rtx, PATTERN (next_trial)) |
| #endif |
| && ! (maybe_never && may_trap_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 new_label = next_real_insn (next_trial); |
| |
| if (new_label != 0) |
| new_label = get_label_before (new_label); |
| else |
| new_label = find_end_label (); |
| |
| delay_list |
| = add_to_delay_list (copy_rtx (next_trial), delay_list); |
| slots_filled++; |
| reorg_redirect_jump (trial, new_label); |
| |
| /* If we merged because we both jumped to the same place, |
| redirect the original insn also. */ |
| if (target) |
| reorg_redirect_jump (insn, new_label); |
| } |
| } |
| |
| /* If this is an unconditional jump, then try to get insns from the |
| target of the jump. */ |
| if (GET_CODE (insn) == JUMP_INSN |
| && simplejump_p (insn) |
| && slots_filled != slots_to_fill) |
| delay_list |
| = fill_slots_from_thread (insn, const_true_rtx, |
| next_active_insn (JUMP_LABEL (insn)), |
| NULL, 1, 1, |
| own_thread_p (JUMP_LABEL (insn), |
| JUMP_LABEL (insn), 0), |
| slots_to_fill, &slots_filled, |
| delay_list); |
| |
| if (delay_list) |
| 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); |
| } |
| |
| #ifdef DELAY_SLOTS_FOR_EPILOGUE |
| /* See if the epilogue needs any delay slots. Try to fill them if so. |
| The only thing we can do is scan backwards from the end of the |
| function. If we did this in a previous pass, it is incorrect to do it |
| again. */ |
| if (current_function_epilogue_delay_list) |
| return; |
| |
| slots_to_fill = DELAY_SLOTS_FOR_EPILOGUE; |
| if (slots_to_fill == 0) |
| return; |
| |
| slots_filled = 0; |
| CLEAR_RESOURCE (&set); |
| |
| /* The frame pointer and stack pointer are needed at the beginning of |
| the epilogue, so instructions setting them can not be put in the |
| epilogue delay slot. However, everything else needed at function |
| end is safe, so we don't want to use end_of_function_needs here. */ |
| CLEAR_RESOURCE (&needed); |
| if (frame_pointer_needed) |
| { |
| SET_HARD_REG_BIT (needed.regs, FRAME_POINTER_REGNUM); |
| #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM |
| SET_HARD_REG_BIT (needed.regs, HARD_FRAME_POINTER_REGNUM); |
| #endif |
| if (! EXIT_IGNORE_STACK |
| || current_function_sp_is_unchanging) |
| SET_HARD_REG_BIT (needed.regs, STACK_POINTER_REGNUM); |
| } |
| else |
| SET_HARD_REG_BIT (needed.regs, STACK_POINTER_REGNUM); |
| |
| #ifdef EPILOGUE_USES |
| for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) |
| { |
| if (EPILOGUE_USES (i)) |
| SET_HARD_REG_BIT (needed.regs, i); |
| } |
| #endif |
| |
| for (trial = get_last_insn (); ! stop_search_p (trial, 1); |
| trial = PREV_INSN (trial)) |
| { |
| if (GET_CODE (trial) == NOTE) |
| continue; |
| pat = PATTERN (trial); |
| if (GET_CODE (pat) == USE || GET_CODE (pat) == CLOBBER) |
| continue; |
| |
| if (! insn_references_resource_p (trial, &set, 1) |
| && ! insn_sets_resource_p (trial, &needed, 1) |
| && ! insn_sets_resource_p (trial, &set, 1) |
| #ifdef HAVE_cc0 |
| /* Don't want to mess with cc0 here. */ |
| && ! reg_mentioned_p (cc0_rtx, pat) |
| #endif |
| && ! can_throw_internal (trial)) |
| { |
| trial = try_split (pat, trial, 1); |
| if (ELIGIBLE_FOR_EPILOGUE_DELAY (trial, slots_filled)) |
| { |
| /* Here as well we are searching backward, so put the |
| insns we find on the head of the list. */ |
| |
| current_function_epilogue_delay_list |
| = gen_rtx_INSN_LIST (VOIDmode, trial, |
| current_function_epilogue_delay_list); |
| mark_end_of_function_resources (trial, 1); |
| update_block (trial, trial); |
| delete_related_insns (trial); |
| |
| /* Clear deleted bit so final.c will output the insn. */ |
| INSN_DELETED_P (trial) = 0; |
| |
| if (slots_to_fill == ++slots_filled) |
| break; |
| continue; |
| } |
| } |
| |
| mark_set_resources (trial, &set, 0, MARK_SRC_DEST_CALL); |
| mark_referenced_resources (trial, &needed, 1); |
| } |
| |
| note_delay_statistics (slots_filled, 0); |
| #endif |
| } |
| |
| /* 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 rtx |
| fill_slots_from_thread (rtx insn, rtx condition, rtx thread, |
| rtx opposite_thread, int likely, int thread_if_true, |
| int own_thread, int slots_to_fill, |
| int *pslots_filled, rtx delay_list) |
| { |
| rtx new_thread; |
| struct resources opposite_needed, set, needed; |
| rtx trial; |
| int lose = 0; |
| int must_annul = 0; |
| int flags; |
| |
| /* Validate our arguments. */ |
| if ((condition == const_true_rtx && ! thread_if_true) |
| || (! own_thread && ! thread_if_true)) |
| abort (); |
| |
| 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 == 0) |
| return delay_list; |
| |
| /* 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 (GET_CODE (trial) == CODE_LABEL) |
| { |
| 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, 1) |
| && ! insn_sets_resource_p (trial, &set, 1) |
| && ! insn_sets_resource_p (trial, &needed, 1) |
| #ifdef HAVE_cc0 |
| && ! (reg_mentioned_p (cc0_rtx, pat) |
| && (! own_thread || ! sets_cc0_p (pat))) |
| #endif |
| && ! can_throw_internal (trial)) |
| { |
| rtx 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. */ |
| if (!must_annul |
| && (condition == const_true_rtx |
| || (! insn_sets_resource_p (trial, &opposite_needed, 1) |
| && ! may_trap_p (pat)))) |
| { |
| 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 (0 |
| #ifdef ANNUL_IFTRUE_SLOTS |
| || ! thread_if_true |
| #endif |
| #ifdef ANNUL_IFFALSE_SLOTS |
| || thread_if_true |
| #endif |
| ) |
| { |
| 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 == NULL) && (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 temp; |
| |
| must_annul = 1; |
| winner: |
| |
| #ifdef HAVE_cc0 |
| if (reg_mentioned_p (cc0_rtx, pat)) |
| link_cc0_insns (trial); |
| #endif |
| |
| /* 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. */ |
| note = find_reg_note (trial, REG_LABEL, 0); |
| /* REG_LABEL could be NOTE_INSN_DELETED_LABEL too. */ |
| if (note && GET_CODE (XEXP (note, 0)) == CODE_LABEL) |
| LABEL_NUSES (XEXP (note, 0))++; |
| |
| delete_related_insns (trial); |
| |
| if (note && GET_CODE (XEXP (note, 0)) == CODE_LABEL) |
| LABEL_NUSES (XEXP (note, 0))--; |
| } |
| else |
| new_thread = next_active_insn (trial); |
| |
| temp = own_thread ? trial : copy_rtx (trial); |
| if (thread_if_true) |
| INSN_FROM_TARGET_P (temp) = 1; |
| |
| delay_list = 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, 1) |
| && ! insn_sets_resource_p (new_thread, &needed, 1) |
| && ! insn_references_resource_p (new_thread, |
| &set, 1) |
| && (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 (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, 1); |
| |
| /* 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 (GET_CODE (trial) == INSN && GET_CODE (pat) == SET |
| && GET_CODE (SET_SRC (pat)) == REG |
| && GET_CODE (SET_DEST (pat)) == REG |
| && !reg_overlap_mentioned_p (SET_DEST (pat), SET_SRC (pat))) |
| { |
| rtx next = next_nonnote_insn (trial); |
| |
| if (next && GET_CODE (next) == INSN |
| && 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 && GET_CODE (trial) == INSN |
| && GET_CODE (PATTERN (trial)) == SEQUENCE |
| && GET_CODE (XVECEXP (PATTERN (trial), 0, 0)) == JUMP_INSN) |
| { |
| /* 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) |
| { |
| delay_list |
| = steal_delay_list_from_target (insn, condition, PATTERN (trial), |
| 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) |
| delay_list |
| = steal_delay_list_from_fallthrough (insn, condition, |
| PATTERN (trial), |
| 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 == 0 && likely && new_thread |
| && GET_CODE (new_thread) == INSN |
| && GET_CODE (PATTERN (new_thread)) != ASM_INPUT |
| && asm_noperands (PATTERN (new_thread)) < 0) |
| { |
| rtx pat = PATTERN (new_thread); |
| rtx dest; |
| rtx src; |
| |
| trial = new_thread; |
| pat = PATTERN (trial); |
| |
| if (GET_CODE (trial) != INSN |
| || GET_CODE (pat) != SET |
| || ! eligible_for_delay (insn, 0, trial, flags) |
| || can_throw_internal (trial)) |
| return 0; |
| |
| dest = SET_DEST (pat), src = SET_SRC (pat); |
| if ((GET_CODE (src) == PLUS || GET_CODE (src) == MINUS) |
| && rtx_equal_p (XEXP (src, 0), dest) |
| && ! reg_overlap_mentioned_p (dest, XEXP (src, 1)) |
| && ! side_effects_p (pat)) |
| { |
| rtx other = XEXP (src, 1); |
| rtx new_arith; |
| rtx ninsn; |
| |
| /* If this is a constant adjustment, use the same code with |
| the negated constant. Otherwise, reverse the sense of the |
| arithmetic. */ |
| if (GET_CODE (other) == CONST_INT) |
| 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 (VOIDmode, dest, new_arith), |
| insn); |
| |
| if (recog_memoized (ninsn) < 0 |
| || (extract_insn (ninsn), ! constrain_operands (1))) |
| { |
| delete_related_insns (ninsn); |
| return 0; |
| } |
| |
| 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_rtx (trial); |
| if (thread_if_true) |
| INSN_FROM_TARGET_P (ninsn) = 1; |
| |
| delay_list = add_to_delay_list (ninsn, NULL_RTX); |
| (*pslots_filled)++; |
| } |
| } |
| |
| if (delay_list && 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; |
| |
| if (! thread_if_true) |
| abort (); |
| |
| if (new_thread && GET_CODE (new_thread) == JUMP_INSN |
| && (simplejump_p (new_thread) |
| || GET_CODE (PATTERN (new_thread)) == RETURN) |
| && redirect_with_delay_list_safe_p (insn, |
| JUMP_LABEL (new_thread), |
| delay_list)) |
| new_thread = follow_jumps (JUMP_LABEL (new_thread)); |
| |
| if (new_thread == 0) |
| label = find_end_label (); |
| else if (GET_CODE (new_thread) == CODE_LABEL) |
| label = new_thread; |
| else |
| label = get_label_before (new_thread); |
| |
| reorg_redirect_jump (insn, label); |
| } |
| |
| return delay_list; |
| } |
| |
| /* 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; |
| 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, fallthrough_insn; |
| rtx delay_list = 0; |
| int own_target; |
| int own_fallthrough; |
| int prediction, slots_to_fill, slots_filled; |
| |
| insn = unfilled_slots_base[i]; |
| if (insn == 0 |
| || INSN_DELETED_P (insn) |
| || GET_CODE (insn) != JUMP_INSN |
| || ! (condjump_p (insn) || condjump_in_parallel_p (insn))) |
| continue; |
| |
| 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; |
| |
| slots_filled = 0; |
| target_label = JUMP_LABEL (insn); |
| condition = get_branch_condition (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 = next_active_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 (insn); |
| own_fallthrough = own_thread_p (NEXT_INSN (insn), NULL_RTX, 1); |
| prediction = mostly_true_jump (insn, condition); |
| } |
| |
| /* 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) |
| { |
| delay_list |
| = fill_slots_from_thread (insn, condition, insn_at_target, |
| fallthrough_insn, prediction == 2, 1, |
| own_target, |
| slots_to_fill, &slots_filled, delay_list); |
| |
| if (delay_list == 0 && 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 (insn); |
| insn_at_target = next_active_insn (target_label); |
| |
| delay_list |
| = fill_slots_from_thread (insn, condition, fallthrough_insn, |
| insn_at_target, 0, 0, |
| own_fallthrough, |
| slots_to_fill, &slots_filled, |
| delay_list); |
| } |
| } |
| else |
| { |
| if (own_fallthrough) |
| delay_list |
| = fill_slots_from_thread (insn, condition, fallthrough_insn, |
| insn_at_target, 0, 0, |
| own_fallthrough, |
| slots_to_fill, &slots_filled, |
| delay_list); |
| |
| if (delay_list == 0) |
| delay_list |
| = fill_slots_from_thread (insn, condition, insn_at_target, |
| next_active_insn (insn), 0, 1, |
| own_target, |
| slots_to_fill, &slots_filled, |
| delay_list); |
| } |
| |
| if (delay_list) |
| 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, 1); |
| } |
| } |
| |
| /* 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 first) |
| { |
| rtx insn, next, pat; |
| rtx trial, delay_insn, target_label; |
| |
| /* Look at every JUMP_INSN and see if we can improve it. */ |
| for (insn = first; insn; insn = next) |
| { |
| rtx other; |
| |
| 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 (GET_CODE (insn) == JUMP_INSN |
| && (condjump_p (insn) || condjump_in_parallel_p (insn)) |
| && (target_label = JUMP_LABEL (insn)) != 0) |
| { |
| target_label = follow_jumps (target_label); |
| /* See comment further down why we must use next_real_insn here, |
| instead of next_active_insn. */ |
| target_label = prev_label (next_real_insn (target_label)); |
| |
| if (target_label == 0) |
| target_label = find_end_label (); |
| |
| if (next_active_insn (target_label) == next |
| && ! condjump_in_parallel_p (insn)) |
| { |
| delete_jump (insn); |
| continue; |
| } |
| |
| if (target_label != JUMP_LABEL (insn)) |
| reorg_redirect_jump (insn, target_label); |
| |
| /* See if this jump branches around an unconditional jump. |
| If so, invert this jump and point it to the target of the |
| second jump. */ |
| if (next && GET_CODE (next) == JUMP_INSN |
| && (simplejump_p (next) || GET_CODE (PATTERN (next)) == RETURN) |
| && next_active_insn (target_label) == next_active_insn (next) |
| && no_labels_between_p (insn, next)) |
| { |
| rtx label = JUMP_LABEL (next); |
| |
| /* Be careful how we do this to avoid deleting code or |
| labels that are momentarily dead. See similar optimization |
| in jump.c. |
| |
| We also need to ensure we properly handle the case when |
| invert_jump fails. */ |
| |
| ++LABEL_NUSES (target_label); |
| if (label) |
| ++LABEL_NUSES (label); |
| |
| if (invert_jump (insn, label, 1)) |
| { |
| delete_related_insns (next); |
| next = insn; |
| } |
| |
| if (label) |
| --LABEL_NUSES (label); |
| |
| if (--LABEL_NUSES (target_label) == 0) |
| delete_related_insns (target_label); |
| |
| continue; |
| } |
| } |
| |
| /* If this is an unconditional jump and the previous insn is a |
| conditional jump, try reversing the condition of the previous |
| insn and swapping our targets. The next pass might be able to |
| fill the slots. |
| |
|