From 6fb5fa3cbc0d78cf9f4ff7cac5e1d8af1e65c5bb Mon Sep 17 00:00:00 2001 From: Daniel Berlin Date: Mon, 11 Jun 2007 18:02:15 +0000 Subject: Merge dataflow branch into mainline From-SVN: r125624 --- gcc/dse.c | 3108 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 3108 insertions(+) create mode 100644 gcc/dse.c (limited to 'gcc/dse.c') diff --git a/gcc/dse.c b/gcc/dse.c new file mode 100644 index 0000000..e846f3f --- /dev/null +++ b/gcc/dse.c @@ -0,0 +1,3108 @@ +/* RTL dead store elimination. + Copyright (C) 2005, 2006, 2007 Free Software Foundation, Inc. + + Contributed by Richard Sandiford + and Kenneth Zadeck + +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, 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301, USA. */ + +#undef BASELINE + +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "hashtab.h" +#include "tm.h" +#include "rtl.h" +#include "tree.h" +#include "regs.h" +#include "hard-reg-set.h" +#include "flags.h" +#include "df.h" +#include "cselib.h" +#include "timevar.h" +#include "tree-pass.h" +#include "alloc-pool.h" +#include "alias.h" +#include "insn-config.h" +#include "expr.h" +#include "recog.h" +#include "dse.h" +#include "dbgcnt.h" + +/* This file contains three techniques for performing Dead Store + Elimination (dse). + + * The first technique performs dse locally on any base address. It + is based on the cselib which is a local value numbering technique. + This technique is local to a basic block but deals with a fairly + general addresses. + + * The second technique performs dse globally but is restricted to + base addresses that are either constant or are relative to the + frame_pointer. + + * The third technique, (which is only done after register allocation) + processes the spill spill slots. This differs from the second + technique because it takes advantage of the fact that spilling is + completely free from the effects of aliasing. + + Logically, dse is a backwards dataflow problem. A store can be + deleted if it if cannot be reached in the backward direction by any + use of the value being stored. However, the local technique uses a + forwards scan of the basic block because cselib requires that the + block be processed in that order. + + The pass is logically broken into 7 steps: + + 0) Initialization. + + 1) The local algorithm, as well as scanning the insns for the two + global algorithms. + + 2) Analysis to see if the global algs are necessary. In the case + of stores base on a constant address, there must be at least two + stores to that address, to make it possible to delete some of the + stores. In the case of stores off of the frame or spill related + stores, only one store to an address is necessary because those + stores die at the end of the function. + + 3) Set up the global dataflow equations based on processing the + info parsed in the first step. + + 4) Solve the dataflow equations. + + 5) Delete the insns that the global analysis has indicated are + unnecessary. + + 6) Cleanup. + + This step uses cselib and canon_rtx to build the largest expression + possible for each address. This pass is a forwards pass through + each basic block. From the point of view of the global technique, + the first pass could examine a block in either direction. The + forwards ordering is to accomodate cselib. + + We a simplifying assumption: addresses fall into four broad + categories: + + 1) base has rtx_varies_p == false, offset is constant. + 2) base has rtx_varies_p == false, offset variable. + 3) base has rtx_varies_p == true, offset constant. + 4) base has rtx_varies_p == true, offset variable. + + The local passes are able to process all 4 kinds of addresses. The + global pass only handles (1). + + The global problem is formulated as follows: + + A store, S1, to address A, where A is not relative to the stack + frame, can be eliminated if all paths from S1 to the end of the + of the function contain another store to A before a read to A. + + If the address A is relative to the stack frame, a store S2 to A + can be eliminated if there are no paths from S1 that reach the + end of the function that read A before another store to A. In + this case S2 can be deleted if there are paths to from S2 to the + end of the function that have no reads or writes to A. This + second case allows stores to the stack frame to be deleted that + would otherwise die when the function returns. This cannot be + done if stores_off_frame_dead_at_return is not true. See the doc + for that variable for when this variable is false. + + The global problem is formulated as a backwards set union + dataflow problem where the stores are the gens and reads are the + kills. Set union problems are rare and require some special + handling given our representation of bitmaps. A straightforward + implementation of requires a lot of bitmaps filled with 1s. + These are expensive and cumbersome in our bitmap formulation so + care has been taken to avoid large vectors filled with 1s. See + the comments in bb_info and in the dataflow confluence functions + for details. + + There are two places for further enhancements to this algorithm: + + 1) The original dse which was embedded in a pass called flow also + did local address forwarding. For example in + + A <- r100 + ... <- A + + flow would replace the right hand side of the second insn with a + reference to r100. Most of the infomation is available to add this + to this pass. It has not done it because it is a lot of work in + the case that either r100 is assigned to between the first and + second insn and/or the second insn is a load of part of the value + stored by the first insn. + + insn 5 in gcc.c-torture/compile/990203-1.c simple case. + insn 15 in gcc.c-torture/execute/20001017-2.c simple case. + insn 25 in gcc.c-torture/execute/20001026-1.c simple case. + insn 44 in gcc.c-torture/execute/20010910-1.c simple case. + + 2) The cleaning up of spill code is quite profitable. It currently + depends on reading tea leaves and chicken entrails left by reload. + This pass depends on reload creating a singleton alias set for each + spill slot and telling the next dse pass which of these alias sets + are the singletons. Rather than analyze the addresses of the + spills, dse's spill processing just does analysis of the loads and + stores that use those alias sets. There are three cases where this + falls short: + + a) Reload sometimes creates the slot for one mode of access, and + then inserts loads and/or stores for a smaller mode. In this + case, the current code just punts on the slot. The proper thing + to do is to back out and use one bit vector position for each + byte of the entity associated with the slot. This depends on + KNOWING that reload always generates the accesses for each of the + bytes in some canonical (read that easy to understand several + passes after reload happens) way. + + b) Reload sometimes decides that spill slot it allocated was not + large enough for the mode and goes back and allocates more slots + with the same mode and alias set. The backout in this case is a + little more graceful than (a). In this case the slot is unmarked + as being a spill slot and if final address comes out to be based + off the frame pointer, the global algorithm handles this slot. + + c) For any pass that may prespill, there is currently no + mechanism to tell the dse pass that the slot being used has the + special properties that reload uses. It may be that all that is + requirred is to have those passes make the same calls that reload + does, assuming that the alias sets can be manipulated in the same + way. */ + +/* There are limits to the size of constant offsets we model for the + global problem. There are certainly test cases, that exceed this + limit, however, it is unlikely that there are important programs + that really have constant offsets this size. */ +#define MAX_OFFSET (64 * 1024) + + +static bitmap scratch = NULL; +struct insn_info; + +/* This structure holds information about a candidate store. */ +struct store_info +{ + + /* False means this is a clobber. */ + bool is_set; + + /* The id of the mem group of the base address. If rtx_varies_p is + true, this is -1. Otherwise, it is the index into the group + table. */ + int group_id; + + /* This is the cselib value. */ + cselib_val *cse_base; + + /* This canonized mem. */ + rtx mem; + + /* The result of get_addr on mem. */ + rtx mem_addr; + + /* If this is non-zero, it is the alias set of a spill location. */ + HOST_WIDE_INT alias_set; + + /* The offset of the first and byte before the last byte associated + with the operation. */ + int begin, end; + + /* An bitmask as wide as the number of bytes in the word that + contains a 1 if the byte may be needed. The store is unused if + all of the bits are 0. */ + long positions_needed; + + /* The next store info for this insn. */ + struct store_info *next; + + /* The right hand side of the store. This is used if there is a + subsequent reload of the mems address somewhere later in the + basic block. */ + rtx rhs; +}; + +typedef struct store_info *store_info_t; +static alloc_pool cse_store_info_pool; +static alloc_pool rtx_store_info_pool; + +/* This structure holds information about a load. These are only + built for rtx bases. */ +struct read_info +{ + /* The id of the mem group of the base address. */ + int group_id; + + /* If this is non-zero, it is the alias set of a spill location. */ + HOST_WIDE_INT alias_set; + + /* The offset of the first and byte after the last byte associated + with the operation. If begin == end == 0, the read did not have + a constant offset. */ + int begin, end; + + /* The mem being read. */ + rtx mem; + + /* The next read_info for this insn. */ + struct read_info *next; +}; +typedef struct read_info *read_info_t; +static alloc_pool read_info_pool; + + +/* One of these records is created for each insn. */ + +struct insn_info +{ + /* Set true if the insn contains a store but the insn itself cannot + be deleted. This is set if the insn is a parallel and there is + more than one non dead output or if the insn is in some way + volatile. */ + bool cannot_delete; + + /* This field is only used by the global algorithm. It is set true + if the insn contains any read of mem except for a (1). This is + also set if the insn is a call or has a clobber mem. If the insn + contains a wild read, the use_rec will be null. */ + bool wild_read; + + /* This field is set for const function calls. Const functions + cannot read memory, but they can read the stack because that is + where they may get their parms. So having this set is less + severe than a wild read, it just means that all of the stores to + the stack are killed rather than all stores. */ + bool stack_read; + + /* This is true if any of the sets within the store contains a + cselib base. Such stores can only be deleted by the local + algorithm. */ + bool contains_cselib_groups; + + /* The insn. */ + rtx insn; + + /* The list of mem sets or mem clobbers that are contained in this + insn. If the insn is deletable, it contains only one mem set. + But it could also contain clobbers. Insns that contain more than + one mem set are not deletable, but each of those mems are here in + order to provied info to delete other insns. */ + store_info_t store_rec; + + /* The linked list of mem uses in this insn. Only the reads from + rtx bases are listed here. The reads to cselib bases are + completely processed during the first scan and so are never + created. */ + read_info_t read_rec; + + /* The prev insn in the basic block. */ + struct insn_info * prev_insn; + + /* The linked list of insns that are in consideration for removal in + the forwards pass thru the basic block. This pointer may be + trash as it is not cleared when a wild read occurs. The only + time it is guaranteed to be correct is when the traveral starts + at active_local_stores. */ + struct insn_info * next_local_store; +}; + +typedef struct insn_info *insn_info_t; +static alloc_pool insn_info_pool; + +/* The linked list of stores that are under consideration in this + basic block. */ +static insn_info_t active_local_stores; + +struct bb_info +{ + + /* Pointer to the insn info for the last insn in the block. These + are linked so this is how all of the insns are reached. During + scanning this is the current insn being scanned. */ + insn_info_t last_insn; + + /* The info for the global dataflow problem. */ + + + /* This is set if the transfer function should and in the wild_read + bitmap before applying the kill and gen sets. That vector knocks + out most of the bits in the bitmap and thus speeds up the + operations. */ + bool apply_wild_read; + + /* The set of store positions that exist in this block before a wild read. */ + bitmap gen; + + /* The set of load positions that exist in this block above the + same position of a store. */ + bitmap kill; + + /* The set of stores that reach the top of the block without being + killed by a read. + + Do not represent the in if it is all ones. Note that this is + what the bitvector should logically be initialized to for a set + intersection problem. However, like the kill set, this is too + expensive. So initially, the in set will only be created for the + exit block and any block that contains a wild read. */ + bitmap in; + + /* The set of stores that reach the bottom of the block from it's + successors. + + Do not represent the in if it is all ones. Note that this is + what the bitvector should logically be initialized to for a set + intersection problem. However, like the kill and in set, this is + too expensive. So what is done is that the confluence operator + just initializes the vector from one of the out sets of the + successors of the block. */ + bitmap out; +}; + +typedef struct bb_info *bb_info_t; +static alloc_pool bb_info_pool; + +/* Table to hold all bb_infos. */ +static bb_info_t *bb_table; + +/* There is a group_info for each rtx base that is used to reference + memory. There are also not many of the rtx bases because they are + very limited in scope. */ + +struct group_info +{ + /* The actual base of the address. */ + rtx rtx_base; + + /* The sequential id of the base. This allows us to have a + canonical ordering of these that is not based on addresses. */ + int id; + + /* A mem wrapped around the base pointer for the group in order to + do read dependency. */ + rtx base_mem; + + /* Canonized version of base_mem, most likely the same thing. */ + rtx canon_base_mem; + + /* These two sets of two bitmaps are used to keep track of how many + stores are actually referencing that postion from this base. We + only do this for rtx bases as this will be used to assign + postions in the bitmaps for the global problem. Bit N is set in + store1 on the first store for offset N. Bit N is set in store2 + for the second store to offset N. This is all we need since we + only care about offsets that have two or more stores for them. + + The "_n" suffix is for offsets less than 0 and the "_p" suffix is + for 0 and greater offsets. + + There is one special case here, for stores into the stack frame, + we will or store1 into store2 before deciding which stores look + at globally. This is because stores to the stack frame that have + no other reads before the end of the function can also be + deleted. */ + bitmap store1_n, store1_p, store2_n, store2_p; + + /* The postions in this bitmap have the same assignments as the in, + out, gen and kill bitmaps. This bitmap is all zeros except for + the postions that are occupied by stores for this group. */ + bitmap group_kill; + + /* True if there are any positions that are to be processed + globally. */ + bool process_globally; + + /* True if the base of this group is either the frame_pointer or + hard_frame_pointer. */ + bool frame_related; + + /* The offset_map is used to map the offsets from this base into + postions in the global bitmaps. It is only created after all of + the all of stores have been scanned and we know which ones we + care about. */ + int *offset_map_n, *offset_map_p; + int offset_map_size_n, offset_map_size_p; +}; +typedef struct group_info *group_info_t; +static alloc_pool rtx_group_info_pool; + +/* Tables of group_info structures, hashed by base value. */ +static htab_t rtx_group_table; + +/* Index into the rtx_group_vec. */ +static int rtx_group_next_id; + +DEF_VEC_P(group_info_t); +DEF_VEC_ALLOC_P(group_info_t,heap); + +static VEC(group_info_t,heap) *rtx_group_vec; + + +/* This structure holds the set of changes that are being deferred + when removing read operation. See replace_read. */ +struct deferred_change +{ + + /* The mem that is being replaced. */ + rtx *loc; + + /* The reg it is being replaced with. */ + rtx reg; + + struct deferred_change *next; +}; + +typedef struct deferred_change *deferred_change_t; +static alloc_pool deferred_change_pool; + +static deferred_change_t deferred_change_list = NULL; + +/* This are used to hold the alias sets of spill variables. Since + these are never aliased and there may be a lot of them, it makes + sense to treat them specially. This bitvector is only allocated in + calls from dse_record_singleton_alias_set which currently is only + made during reload1. So when dse is called before reload this + mechanism does nothing. */ + +static bitmap clear_alias_sets = NULL; + +/* The set of clear_alias_sets that have been disqualified because + there are loads or stores using a different mode than the alias set + was registered with. */ +static bitmap disqualified_clear_alias_sets = NULL; + +/* The group that holds all of the clear_alias_sets. */ +static group_info_t clear_alias_group; + +/* The modes of the clear_alias_sets. */ +static htab_t clear_alias_mode_table; + +/* Hash table element to look up the mode for an alias set. */ +struct clear_alias_mode_holder +{ + HOST_WIDE_INT alias_set; + enum machine_mode mode; +}; + +static alloc_pool clear_alias_mode_pool; + +/* This is true except for two cases: + (1) current_function_stdarg -- i.e. we cannot do this + for vararg functions because they play games with the frame. + (2) In ada, it is sometimes not safe to do assume that any stores + based off the stack frame go dead at the exit to a function. */ +static bool stores_off_frame_dead_at_return; + +/* Counter for stats. */ +static int globally_deleted; +static int locally_deleted; +static int spill_deleted; + +static bitmap all_blocks; + +/* The number of bits used in the global bitmaps. */ +static unsigned int current_position; + + +static bool gate_dse (void); + + +/*---------------------------------------------------------------------------- + Zeroth step. + + Initialization. +----------------------------------------------------------------------------*/ + +/* Hashtable callbacks for maintaining the "bases" field of + store_group_info, given that the addresses are function invariants. */ + +static int +clear_alias_mode_eq (const void *p1, const void *p2) +{ + const struct clear_alias_mode_holder * h1 + = (const struct clear_alias_mode_holder *) p1; + const struct clear_alias_mode_holder * h2 + = (const struct clear_alias_mode_holder *) p2; + return h1->alias_set == h2->alias_set; +} + + +static hashval_t +clear_alias_mode_hash (const void *p) +{ + const struct clear_alias_mode_holder *holder + = (const struct clear_alias_mode_holder *) p; + return holder->alias_set; +} + + +/* Find the entry associated with ALIAS_SET. */ + +static struct clear_alias_mode_holder * +clear_alias_set_lookup (HOST_WIDE_INT alias_set) +{ + struct clear_alias_mode_holder tmp_holder; + void **slot; + + tmp_holder.alias_set = alias_set; + slot = htab_find_slot (clear_alias_mode_table, &tmp_holder, NO_INSERT); + gcc_assert (*slot); + + return *slot; +} + + +/* Hashtable callbacks for maintaining the "bases" field of + store_group_info, given that the addresses are function invariants. */ + +static int +invariant_group_base_eq (const void *p1, const void *p2) +{ + const group_info_t gi1 = (const group_info_t) p1; + const group_info_t gi2 = (const group_info_t) p2; + return rtx_equal_p (gi1->rtx_base, gi2->rtx_base); +} + + +static hashval_t +invariant_group_base_hash (const void *p) +{ + const group_info_t gi = (const group_info_t) p; + int do_not_record; + return hash_rtx (gi->rtx_base, Pmode, &do_not_record, NULL, false); +} + + +/* Get the GROUP for BASE. Add a new group if it is not there. */ + +static group_info_t +get_group_info (rtx base) +{ + struct group_info tmp_gi; + group_info_t gi; + void **slot; + + if (base) + { + /* Find the store_base_info structure for BASE, creating a new one + if necessary. */ + tmp_gi.rtx_base = base; + slot = htab_find_slot (rtx_group_table, &tmp_gi, INSERT); + gi = (group_info_t) *slot; + } + else + { + if (!clear_alias_group) + { + clear_alias_group = gi = pool_alloc (rtx_group_info_pool); + memset (gi, 0, sizeof (struct group_info)); + gi->id = rtx_group_next_id++; + gi->store1_n = BITMAP_ALLOC (NULL); + gi->store1_p = BITMAP_ALLOC (NULL); + gi->store2_n = BITMAP_ALLOC (NULL); + gi->store2_p = BITMAP_ALLOC (NULL); + gi->group_kill = BITMAP_ALLOC (NULL); + gi->process_globally = false; + gi->offset_map_size_n = 0; + gi->offset_map_size_p = 0; + gi->offset_map_n = NULL; + gi->offset_map_p = NULL; + VEC_safe_push (group_info_t, heap, rtx_group_vec, gi); + } + return clear_alias_group; + } + + if (gi == NULL) + { + *slot = gi = pool_alloc (rtx_group_info_pool); + gi->rtx_base = base; + gi->id = rtx_group_next_id++; + gi->base_mem = gen_rtx_MEM (QImode, base); + gi->canon_base_mem = canon_rtx (gi->base_mem); + gi->store1_n = BITMAP_ALLOC (NULL); + gi->store1_p = BITMAP_ALLOC (NULL); + gi->store2_n = BITMAP_ALLOC (NULL); + gi->store2_p = BITMAP_ALLOC (NULL); + gi->group_kill = BITMAP_ALLOC (NULL); + gi->process_globally = false; + gi->frame_related = + (base == frame_pointer_rtx) || (base == hard_frame_pointer_rtx); + gi->offset_map_size_n = 0; + gi->offset_map_size_p = 0; + gi->offset_map_n = NULL; + gi->offset_map_p = NULL; + VEC_safe_push (group_info_t, heap, rtx_group_vec, gi); + } + + return gi; +} + + +/* Initialization of data structures. */ + +static void +dse_step0 (void) +{ + locally_deleted = 0; + globally_deleted = 0; + spill_deleted = 0; + + scratch = BITMAP_ALLOC (NULL); + + rtx_store_info_pool + = create_alloc_pool ("rtx_store_info_pool", + sizeof (struct store_info), 100); + read_info_pool + = create_alloc_pool ("read_info_pool", + sizeof (struct read_info), 100); + insn_info_pool + = create_alloc_pool ("insn_info_pool", + sizeof (struct insn_info), 100); + bb_info_pool + = create_alloc_pool ("bb_info_pool", + sizeof (struct bb_info), 100); + rtx_group_info_pool + = create_alloc_pool ("rtx_group_info_pool", + sizeof (struct group_info), 100); + deferred_change_pool + = create_alloc_pool ("deferred_change_pool", + sizeof (struct deferred_change), 10); + + rtx_group_table = htab_create (11, invariant_group_base_hash, + invariant_group_base_eq, NULL); + + bb_table = XCNEWVEC (bb_info_t, last_basic_block); + rtx_group_next_id = 0; + + stores_off_frame_dead_at_return = + (!(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE + && (TYPE_RETURNS_STACK_DEPRESSED (TREE_TYPE (current_function_decl))))) + && (!current_function_stdarg); + + init_alias_analysis (); + + if (clear_alias_sets) + clear_alias_group = get_group_info (NULL); + else + clear_alias_group = NULL; +} + + + +/*---------------------------------------------------------------------------- + First step. + + Scan all of the insns. Any random ordering of the blocks is fine. + Each block is scanned in forward order to accomodate cselib which + is used to remove stores with non-constant bases. +----------------------------------------------------------------------------*/ + +/* Delete all of the store_info recs from INSN_INFO. */ + +static void +free_store_info (insn_info_t insn_info) +{ + store_info_t store_info = insn_info->store_rec; + while (store_info) + { + store_info_t next = store_info->next; + if (store_info->cse_base) + pool_free (cse_store_info_pool, store_info); + else + pool_free (rtx_store_info_pool, store_info); + store_info = next; + } + + insn_info->cannot_delete = true; + insn_info->contains_cselib_groups = false; + insn_info->store_rec = NULL; +} + + +struct insn_size { + int size; + rtx insn; +}; + + +/* Add an insn to do the add inside a x if it is a + PRE/POST-INC/DEC/MODIFY. D is an structure containing the insn and + the size of the mode of the MEM that this is inside of. */ + +static int +replace_inc_dec (rtx *r, void *d) +{ + rtx x = *r; + struct insn_size *data = (struct insn_size *)d; + switch (GET_CODE (x)) + { + case PRE_INC: + case POST_INC: + { + rtx r1 = XEXP (x, 0); + rtx c = gen_int_mode (Pmode, data->size); + add_insn_before (data->insn, + gen_rtx_SET (Pmode, r1, + gen_rtx_PLUS (Pmode, r1, c)), + NULL); + return -1; + } + + case PRE_DEC: + case POST_DEC: + { + rtx r1 = XEXP (x, 0); + rtx c = gen_int_mode (Pmode, -data->size); + add_insn_before (data->insn, + gen_rtx_SET (Pmode, r1, + gen_rtx_PLUS (Pmode, r1, c)), + NULL); + return -1; + } + + case PRE_MODIFY: + case POST_MODIFY: + { + /* We can resuse the add because we are about to delete the + insn that contained it. */ + rtx add = XEXP (x, 0); + rtx r1 = XEXP (add, 0); + add_insn_before (data->insn, + gen_rtx_SET (Pmode, r1, add), NULL); + return -1; + } + + default: + return 0; + } +} + + +/* If X is a MEM, check the address to see if it is PRE/POST-INC/DEC/MODIFY + and generate an add to replace that. */ + +static int +replace_inc_dec_mem (rtx *r, void *d) +{ + rtx x = *r; + if (GET_CODE (x) == MEM) + { + struct insn_size data; + + data.size = GET_MODE_SIZE (GET_MODE (x)); + data.insn = (rtx)d; + + for_each_rtx (&XEXP (x, 0), replace_inc_dec, &data); + + return -1; + } + return 0; +} + +/* Before we delete INSN, make sure that the auto inc/dec, if it is + there, is split into a separate insn. */ + +static void +check_for_inc_dec (rtx insn) +{ + rtx note = find_reg_note (insn, REG_INC, NULL_RTX); + if (note) + for_each_rtx (&insn, replace_inc_dec_mem, insn); +} + + +/* Delete the insn and free all of the fields inside INSN_INFO. */ + +static void +delete_dead_store_insn (insn_info_t insn_info) +{ + read_info_t read_info; + + if (!dbg_cnt (dse)) + return; + + check_for_inc_dec (insn_info->insn); + if (dump_file) + { + fprintf (dump_file, "Locally deleting insn %d ", + INSN_UID (insn_info->insn)); + if (insn_info->store_rec->alias_set) + fprintf (dump_file, "alias set %d\n", + (int)insn_info->store_rec->alias_set); + else + fprintf (dump_file, "\n"); + } + + free_store_info (insn_info); + read_info = insn_info->read_rec; + + while (read_info) + { + read_info_t next = read_info->next; + pool_free (read_info_pool, read_info); + read_info = next; + } + insn_info->read_rec = NULL; + + delete_insn (insn_info->insn); + locally_deleted++; + insn_info->insn = NULL; + + insn_info->wild_read = false; +} + + +/* Set the store* bitmaps offset_map_size* fields in GROUP based on + OFFSET and WIDTH. */ + +static void +set_usage_bits (group_info_t group, HOST_WIDE_INT offset, HOST_WIDE_INT width) +{ + HOST_WIDE_INT i; + + if ((offset > -MAX_OFFSET) && (offset < MAX_OFFSET)) + for (i=offset; istore1_n; + store2 = group->store2_n; + ai = -i; + } + else + { + store1 = group->store1_p; + store2 = group->store2_p; + ai = i; + } + + if (bitmap_bit_p (store1, ai)) + bitmap_set_bit (store2, ai); + else + { + bitmap_set_bit (store1, ai); + if (i < 0) + { + if (group->offset_map_size_n < ai) + group->offset_map_size_n = ai; + } + else + { + if (group->offset_map_size_p < ai) + group->offset_map_size_p = ai; + } + } + } +} + + +/* Set the BB_INFO so that the last insn is marked as a wild read. */ + +static void +add_wild_read (bb_info_t bb_info) +{ + insn_info_t insn_info = bb_info->last_insn; + read_info_t *ptr = &insn_info->read_rec; + + while (*ptr) + { + read_info_t next = (*ptr)->next; + if ( (*ptr)->alias_set == 0 ) + { + pool_free (read_info_pool, *ptr); + *ptr = next; + } + else + ptr = &(*ptr)->next; + } + insn_info->wild_read = true; + active_local_stores = NULL; +} + + +/* Return true if X is a constant or one of the registers that behaves + as a constant over the life of a function. */ + +static bool +const_or_frame_p (rtx x) +{ + switch (GET_CODE (x)) + { + case MEM: + return MEM_READONLY_P (x); + + case CONST: + case CONST_INT: + case CONST_DOUBLE: + case CONST_VECTOR: + case SYMBOL_REF: + case LABEL_REF: + return true; + + case REG: + /* Note that we have to test for the actual rtx used for the frame + and arg pointers and not just the register number in case we have + eliminated the frame and/or arg pointer and are using it + for pseudos. */ + if (x == frame_pointer_rtx || x == hard_frame_pointer_rtx + /* The arg pointer varies if it is not a fixed register. */ + || (x == arg_pointer_rtx && fixed_regs[ARG_POINTER_REGNUM]) + || x == pic_offset_table_rtx) + return true; + return false; + + default: + return false; + } +} + +/* Take all reasonable action to put the address of MEM into the form + that we can do analysis on. + + The gold standard is to get the address into the form: address + + OFFSET where address is something that rtx_varies_p considers a + constant. When we can get the address in this form, we can do + global analysis on it. Note that for constant bases, address is + not actually returned, only the group_id. The address can be + obtained from that. + + If that fails, we try cselib to get a value we can at least use + locally. If that fails we return false. + + The GROUP_ID is set to -1 for cselib bases and the index of the + group for non_varying bases. + + FOR_READ is true if this is a mem read and false if not. */ + +static bool +canon_address (rtx mem, + HOST_WIDE_INT *alias_set_out, + int *group_id, + HOST_WIDE_INT *offset, + cselib_val **base) +{ + rtx mem_address = XEXP (mem, 0); + rtx expanded_address, address; + /* Make sure that cselib is has initialized all of the operands of + the address before asking it to do the subst. */ + + if (clear_alias_sets) + { + /* If this is a spill, do not do any further processing. */ + HOST_WIDE_INT alias_set = MEM_ALIAS_SET (mem); + if (dump_file) + fprintf (dump_file, "found alias set %d\n", (int)alias_set); + if (bitmap_bit_p (clear_alias_sets, alias_set)) + { + struct clear_alias_mode_holder *entry + = clear_alias_set_lookup (alias_set); + + /* If the modes do not match, we cannot process this set. */ + if (entry->mode != GET_MODE (mem)) + { + if (dump_file) + fprintf (dump_file, + "disqualifying alias set %d, (%s) != (%s)\n", + (int)alias_set, GET_MODE_NAME (entry->mode), + GET_MODE_NAME (GET_MODE (mem))); + + bitmap_set_bit (disqualified_clear_alias_sets, alias_set); + return false; + } + + *alias_set_out = alias_set; + *group_id = clear_alias_group->id; + return true; + } + } + + *alias_set_out = 0; + + cselib_lookup (mem_address, Pmode, 1); + + if (dump_file) + { + fprintf (dump_file, " mem: "); + print_inline_rtx (dump_file, mem_address, 0); + fprintf (dump_file, "\n"); + } + + /* Use cselib to replace all of the reg references with the full + expression. This will take care of the case where we have + + r_x = base + offset; + val = *r_x; + + by making it into + + val = *(base + offset); + */ + + expanded_address = cselib_expand_value_rtx (mem_address, scratch, 5); + + /* If this fails, just go with the mem_address. */ + if (!expanded_address) + expanded_address = mem_address; + + /* Split the address into canonical BASE + OFFSET terms. */ + address = canon_rtx (expanded_address); + + *offset = 0; + + if (dump_file) + { + fprintf (dump_file, "\n after cselib_expand address: "); + print_inline_rtx (dump_file, expanded_address, 0); + fprintf (dump_file, "\n"); + + fprintf (dump_file, "\n after canon_rtx address: "); + print_inline_rtx (dump_file, address, 0); + fprintf (dump_file, "\n"); + } + + if (GET_CODE (address) == CONST) + address = XEXP (address, 0); + + if (GET_CODE (address) == PLUS && GET_CODE (XEXP (address, 1)) == CONST_INT) + { + *offset = INTVAL (XEXP (address, 1)); + address = XEXP (address, 0); + } + + if (const_or_frame_p (address)) + { + group_info_t group = get_group_info (address); + + if (dump_file) + fprintf (dump_file, " gid=%d offset=%d \n", group->id, (int)*offset); + *base = NULL; + *group_id = group->id; + } + else + { + *base = cselib_lookup (address, Pmode, true); + *group_id = -1; + + if (*base == NULL) + { + if (dump_file) + fprintf (dump_file, " no cselib val - should be a wild read.\n"); + return false; + } + if (dump_file) + fprintf (dump_file, " varying cselib base=%d offset = %d\n", + (*base)->value, (int)*offset); + } + return true; +} + + +/* Clear the rhs field from the active_local_stores array. */ + +static void +clear_rhs_from_active_local_stores (void) +{ + insn_info_t ptr = active_local_stores; + + while (ptr) + { + store_info_t store_info = ptr->store_rec; + /* Skip the clobbers. */ + while (!store_info->is_set) + store_info = store_info->next; + + store_info->rhs = NULL; + + ptr = ptr->next_local_store; + } +} + + +/* BODY is an instruction pattern that belongs to INSN. Return 1 if + there is a candidate store, after adding it to the appropriate + local store group if so. */ + +static int +record_store (rtx body, bb_info_t bb_info) +{ + rtx mem; + HOST_WIDE_INT offset = 0; + HOST_WIDE_INT width = 0; + HOST_WIDE_INT spill_alias_set; + insn_info_t insn_info = bb_info->last_insn; + store_info_t store_info = NULL; + int group_id; + cselib_val *base = NULL; + insn_info_t ptr, last; + bool store_is_unused; + + if (GET_CODE (body) != SET && GET_CODE (body) != CLOBBER) + return 0; + + /* If this is not used, then this cannot be used to keep the insn + from being deleted. On the other hand, it does provide something + that can be used to prove that another store is dead. */ + store_is_unused + = (find_reg_note (insn_info->insn, REG_UNUSED, body) != NULL); + + /* Check whether that value is a suitable memory location. */ + mem = SET_DEST (body); + if (!MEM_P (mem)) + { + /* If the set or clobber is unused, then it does not effect our + ability to get rid of the entire insn. */ + if (!store_is_unused) + insn_info->cannot_delete = true; + return 0; + } + + /* At this point we know mem is a mem. */ + if (GET_MODE (mem) == BLKmode) + { + if (GET_CODE (XEXP (mem, 0)) == SCRATCH) + { + if (dump_file) + fprintf (dump_file, " adding wild read for (clobber (mem:BLK (scratch))\n"); + add_wild_read (bb_info); + insn_info->cannot_delete = true; + } + else if (!store_is_unused) + { + /* If the set or clobber is unused, then it does not effect our + ability to get rid of the entire insn. */ + insn_info->cannot_delete = true; + clear_rhs_from_active_local_stores (); + } + return 0; + } + + /* We can still process a volatile mem, we just cannot delete it. */ + if (MEM_VOLATILE_P (mem)) + insn_info->cannot_delete = true; + + if (!canon_address (mem, &spill_alias_set, &group_id, &offset, &base)) + { + clear_rhs_from_active_local_stores (); + return 0; + } + + width = GET_MODE_SIZE (GET_MODE (mem)); + + if (spill_alias_set) + { + bitmap store1 = clear_alias_group->store1_p; + bitmap store2 = clear_alias_group->store2_p; + + if (bitmap_bit_p (store1, spill_alias_set)) + bitmap_set_bit (store2, spill_alias_set); + else + bitmap_set_bit (store1, spill_alias_set); + + if (clear_alias_group->offset_map_size_p < spill_alias_set) + clear_alias_group->offset_map_size_p = spill_alias_set; + + store_info = pool_alloc (rtx_store_info_pool); + + if (dump_file) + fprintf (dump_file, " processing spill store %d(%s)\n", + (int)spill_alias_set, GET_MODE_NAME (GET_MODE (mem))); + } + else if (group_id >= 0) + { + /* In the restrictive case where the base is a constant or the + frame pointer we can do global analysis. */ + + group_info_t group + = VEC_index (group_info_t, rtx_group_vec, group_id); + + store_info = pool_alloc (rtx_store_info_pool); + set_usage_bits (group, offset, width); + + if (dump_file) + fprintf (dump_file, " processing const base store gid=%d[%d..%d)\n", + group_id, (int)offset, (int)(offset+width)); + } + else + { + store_info = pool_alloc (cse_store_info_pool); + insn_info->contains_cselib_groups = true; + group_id = -1; + + if (dump_file) + fprintf (dump_file, " processing cselib store [%d..%d)\n", + (int)offset, (int)(offset+width)); + } + + /* Check to see if this stores causes some other stores to be + dead. */ + ptr = active_local_stores; + last = NULL; + + while (ptr) + { + insn_info_t next = ptr->next_local_store; + store_info_t s_info = ptr->store_rec; + bool delete = true; + + /* Skip the clobbers. We delete the active insn if this insn + shaddows the set. To have been put on the active list, it + has exactly on set. */ + while (!s_info->is_set) + s_info = s_info->next; + + if (s_info->alias_set != spill_alias_set) + delete = false; + else if (s_info->alias_set) + { + struct clear_alias_mode_holder *entry + = clear_alias_set_lookup (s_info->alias_set); + /* Generally, spills cannot be processed if and of the + references to the slot have a different mode. But if + we are in the same block and mode is exactly the same + between this store and one before in the same block, + we can still delete it. */ + if ((GET_MODE (mem) == GET_MODE (s_info->mem)) + && (GET_MODE (mem) == entry->mode)) + { + delete = true; + s_info->positions_needed = 0; + } + if (dump_file) + fprintf (dump_file, " trying spill store in insn=%d alias_set=%d\n", + INSN_UID (ptr->insn), (int)s_info->alias_set); + } + else if ((s_info->group_id == group_id) + && (s_info->cse_base == base)) + { + HOST_WIDE_INT i; + if (dump_file) + fprintf (dump_file, " trying store in insn=%d gid=%d[%d..%d)\n", + INSN_UID (ptr->insn), s_info->group_id, + (int)s_info->begin, (int)s_info->end); + for (i = offset; i < offset+width; i++) + if (i >= s_info->begin && i < s_info->end) + s_info->positions_needed &= ~(1L << (i - s_info->begin)); + } + else if (s_info->rhs) + /* Need to see if it is possible for this store to overwrite + the value of store_info. If it is, set the rhs to NULL to + keep it from being used to remove a load. */ + { + if (canon_true_dependence (s_info->mem, + GET_MODE (s_info->mem), + s_info->mem_addr, + mem, rtx_varies_p)) + s_info->rhs = NULL; + } + + /* An insn can be deleted if every position of every one of + its s_infos is zero. */ + if (s_info->positions_needed != 0) + delete = false; + + if (delete) + { + insn_info_t insn_to_delete = ptr; + + if (last) + last->next_local_store = ptr->next_local_store; + else + active_local_stores = ptr->next_local_store; + + delete_dead_store_insn (insn_to_delete); + } + else + last = ptr; + + ptr = next; + } + + gcc_assert ((unsigned) width < sizeof (store_info->positions_needed) * CHAR_BIT); + + /* Finish filling in the store_info. */ + store_info->next = insn_info->store_rec; + insn_info->store_rec = store_info; + store_info->mem = canon_rtx (mem); + store_info->alias_set = spill_alias_set; + store_info->mem_addr = get_addr (XEXP (mem, 0)); + store_info->cse_base = base; + store_info->positions_needed = (1L << width) - 1; + store_info->group_id = group_id; + store_info->begin = offset; + store_info->end = offset + width; + store_info->is_set = GET_CODE (body) == SET; + + if (store_info->is_set + /* No place to keep the value after ra. */ + && !reload_completed + /* The careful reviewer may wish to comment my checking that the + rhs of a store is always a reg. */ + && REG_P (SET_SRC (body)) + /* Sometimes the store and reload is used for truncation and + rounding. */ + && !(FLOAT_MODE_P (GET_MODE (mem)) && (flag_float_store))) + store_info->rhs = SET_SRC (body); + else + store_info->rhs = NULL; + + /* If this is a clobber, we return 0. We will only be able to + delete this insn if there is only one store USED store, but we + can use the clobber to delete other stores earlier. */ + return store_info->is_set ? 1 : 0; +} + + +static void +dump_insn_info (const char * start, insn_info_t insn_info) +{ + fprintf (dump_file, "%s insn=%d %s\n", start, + INSN_UID (insn_info->insn), + insn_info->store_rec ? "has store" : "naked"); +} + + +/* Take a sequence of: + A <- r1 + ... + ... <- A + + and change it into + r2 <- r1 + A <- r1 + ... + ... <- r2 + + The STORE_INFO and STORE_INFO are for the store and the READ_INFO + and READ_INSN are for the read. Return true if the replacement + went ok. */ + +static bool +replace_read (store_info_t store_info, insn_info_t store_insn, + read_info_t read_info, insn_info_t read_insn, rtx *loc) +{ + if (!dbg_cnt (dse)) + return false; + + if (dump_file) + fprintf (dump_file, "generating move to replace load at %d from store at %d\n", + INSN_UID (read_insn->insn), INSN_UID (store_insn->insn)); + if (GET_MODE (store_info->mem) == GET_MODE (read_info->mem)) + { + rtx new_reg = gen_reg_rtx (GET_MODE (store_info->mem)); + if (validate_change (read_insn->insn, loc, new_reg, 0)) + { + rtx insns; + deferred_change_t deferred_change = pool_alloc (deferred_change_pool); + + start_sequence (); + emit_move_insn (new_reg, store_info->rhs); + insns = get_insns (); + end_sequence (); + emit_insn_before (insns, store_insn->insn); + + if (dump_file) + fprintf (dump_file, " -- adding move insn %d: r%d = r%d\n", + INSN_UID (insns), REGNO (new_reg), REGNO (store_info->rhs)); + + /* And now for the cludge part: cselib croaks if you just + return at this point. There are two reasons for this: + + 1) Cselib has an idea of how many pseudos there are and + that does not include the new one we just added. + + 2) Cselib does not know about the move insn we added + above the store_info, and there is no way to tell it + about it, because it has "moved on". + + So we are just going to have to lie. The move insn is + not really an issue, cselib did not see it. But the use + of the new pseudo read_insn is a real problem. The way + that we solve this problem is that we are just going to + put the mem back keep a table of mems to get rid of. At + the end of the basic block we can put it back. */ + + *loc = read_info->mem; + deferred_change->next = deferred_change_list; + deferred_change_list = deferred_change; + deferred_change->loc = loc; + deferred_change->reg = new_reg; + + /* Get rid of the read_info, from the point of view of the + rest of dse, play like this read never happened. */ + read_insn->read_rec = read_info->next; + pool_free (read_info_pool, read_info); + return true; + } + else + { + if (dump_file) + fprintf (dump_file, " -- validation failure\n"); + return false; + } + } + else + { + /* Someone with excellent rtl skills needs to fill this in. You + are guaranteed that the read is of the same size or smaller + than the store, and that the read does not hang off one of + the ends of the store. But the offsets of each must be + checked because the read does not have to line up on either + end of the store so the begin fields need to be examined in + both the store_info and read_info. */ + if (dump_file) + fprintf (dump_file, " -- complex load, currently unsupported.\n"); + return false; + } +} + + +/* A for_each_rtx callback in which DATA is the bb_info. Check to see + if LOC is a mem and if it is look at the address and kill any + appropriate stores that may be active. */ + +static int +check_mem_read_rtx (rtx *loc, void *data) +{ + rtx mem = *loc; + bb_info_t bb_info; + insn_info_t insn_info; + HOST_WIDE_INT offset = 0; + HOST_WIDE_INT width = 0; + HOST_WIDE_INT spill_alias_set = 0; + cselib_val *base = NULL; + int group_id; + read_info_t read_info; + + if (!mem || !MEM_P (mem)) + return 0; + + bb_info = (bb_info_t) data; + insn_info = bb_info->last_insn; + + if ((MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER) + || (MEM_VOLATILE_P (mem))) + { + if (dump_file) + fprintf (dump_file, " adding wild read, volatile or barrier.\n"); + add_wild_read (bb_info); + insn_info->cannot_delete = true; + return 0; + } + + /* If it is reading readonly mem, then there can be no conflict with + another write. */ + if (MEM_READONLY_P (mem)) + return 0; + + if (!canon_address (mem, &spill_alias_set, &group_id, &offset, &base)) + { + if (dump_file) + fprintf (dump_file, " adding wild read, canon_address failure.\n"); + add_wild_read (bb_info); + return 0; + } + + if (GET_MODE (mem) == BLKmode) + width = -1; + else + width = GET_MODE_SIZE (GET_MODE (mem)); + + read_info = pool_alloc (read_info_pool); + read_info->group_id = group_id; + read_info->mem = mem; + read_info->alias_set = spill_alias_set; + read_info->begin = offset; + read_info->end = offset + width; + read_info->next = insn_info->read_rec; + insn_info->read_rec = read_info; + + /* We ignore the clobbers in store_info. The is mildly agressive, + but there really should not be a clobber followed by a read. */ + + if (spill_alias_set) + { + insn_info_t i_ptr = active_local_stores; + insn_info_t last = NULL; + + if (dump_file) + fprintf (dump_file, " processing spill load %d\n", + (int)spill_alias_set); + + while (i_ptr) + { + store_info_t store_info = i_ptr->store_rec; + + /* Skip the clobbers. */ + while (!store_info->is_set) + store_info = store_info->next; + + if (store_info->alias_set == spill_alias_set) + { + if (dump_file) + dump_insn_info ("removing from active", i_ptr); + + if (last) + last->next_local_store = i_ptr->next_local_store; + else + active_local_stores = i_ptr->next_local_store; + } + else + last = i_ptr; + i_ptr = i_ptr->next_local_store; + } + } + else if (group_id >= 0) + { + /* This is the restricted case where the base is a constant or + the frame pointer and offset is a constant. */ + insn_info_t i_ptr = active_local_stores; + insn_info_t last = NULL; + + if (dump_file) + { + if (width == -1) + fprintf (dump_file, " processing const load gid=%d[BLK]\n", + group_id); + else + fprintf (dump_file, " processing const load gid=%d[%d..%d)\n", + group_id, (int)offset, (int)(offset+width)); + } + + while (i_ptr) + { + bool remove = false; + store_info_t store_info = i_ptr->store_rec; + + /* Skip the clobbers. */ + while (!store_info->is_set) + store_info = store_info->next; + + /* There are three cases here. */ + if (store_info->group_id < 0) + /* We have a cselib store followed by a read from a + const base. */ + remove + = canon_true_dependence (store_info->mem, + GET_MODE (store_info->mem), + store_info->mem_addr, + mem, rtx_varies_p); + + else if (group_id == store_info->group_id) + { + /* This is a block mode load. We may get lucky and + canon_true_dependence may save the day. */ + if (width == -1) + remove + = canon_true_dependence (store_info->mem, + GET_MODE (store_info->mem), + store_info->mem_addr, + mem, rtx_varies_p); + + /* If this read is just reading back something that we just + stored, rewrite the read. */ + else + { + if (store_info->rhs + && (offset >= store_info->begin) + && (offset + width <= store_info->end)) + { + int mask = ((1L << width) - 1) << (offset - store_info->begin); + + if ((store_info->positions_needed & mask) == mask + && replace_read (store_info, i_ptr, + read_info, insn_info, loc)) + return 0; + } + /* The bases are the same, just see if the offsets + overlap. */ + if ((offset < store_info->end) + && (offset + width > store_info->begin)) + remove = true; + } + } + + /* else + The else case that is missing here is that the + bases are constant but different. There is nothing + to do here because there is no overlap. */ + + if (remove) + { + if (dump_file) + dump_insn_info ("removing from active", i_ptr); + + if (last) + last->next_local_store = i_ptr->next_local_store; + else + active_local_stores = i_ptr->next_local_store; + } + else + last = i_ptr; + i_ptr = i_ptr->next_local_store; + } + } + else + { + insn_info_t i_ptr = active_local_stores; + insn_info_t last = NULL; + if (dump_file) + { + fprintf (dump_file, " processing cselib load mem:"); + print_inline_rtx (dump_file, mem, 0); + fprintf (dump_file, "\n"); + } + + while (i_ptr) + { + bool remove = false; + store_info_t store_info = i_ptr->store_rec; + + if (dump_file) + fprintf (dump_file, " processing cselib load against insn %d\n", + INSN_UID (i_ptr->insn)); + + /* Skip the clobbers. */ + while (!store_info->is_set) + store_info = store_info->next; + + /* If this read is just reading back something that we just + stored, rewrite the read. */ + if (store_info->rhs + && store_info->group_id == -1 + && store_info->cse_base == base + && (offset >= store_info->begin) + && (offset + width <= store_info->end)) + { + int mask = ((1L << width) - 1) << (offset - store_info->begin); + + if ((store_info->positions_needed & mask) == mask + && replace_read (store_info, i_ptr, + read_info, insn_info, loc)) + return 0; + } + + if (!store_info->alias_set) + remove = canon_true_dependence (store_info->mem, + GET_MODE (store_info->mem), + store_info->mem_addr, + mem, rtx_varies_p); + + if (remove) + { + if (dump_file) + dump_insn_info ("removing from active", i_ptr); + + if (last) + last->next_local_store = i_ptr->next_local_store; + else + active_local_stores = i_ptr->next_local_store; + } + else + last = i_ptr; + i_ptr = i_ptr->next_local_store; + } + } + return 0; +} + +/* A for_each_rtx callback in which DATA points the INSN_INFO for + as check_mem_read_rtx. Nullify the pointer if i_m_r_m_r returns + true for any part of *LOC. */ + +static void +check_mem_read_use (rtx *loc, void *data) +{ + for_each_rtx (loc, check_mem_read_rtx, data); +} + +/* Apply record_store to all candidate stores in INSN. Mark INSN + if some part of it is not a candidate store and assigns to a + non-register target. */ + +static void +scan_insn (bb_info_t bb_info, rtx insn) +{ + rtx body; + insn_info_t insn_info = pool_alloc (insn_info_pool); + int mems_found = 0; + memset (insn_info, 0, sizeof (struct insn_info)); + + if (dump_file) + fprintf (dump_file, "\n**scanning insn=%d\n", + INSN_UID (insn)); + + insn_info->prev_insn = bb_info->last_insn; + insn_info->insn = insn; + bb_info->last_insn = insn_info; + + + /* Cselib clears the table for this case, so we have to essentually + do the same. */ + if (NONJUMP_INSN_P (insn) + && GET_CODE (PATTERN (insn)) == ASM_OPERANDS + && MEM_VOLATILE_P (PATTERN (insn))) + { + add_wild_read (bb_info); + insn_info->cannot_delete = true; + return; + } + + /* Look at all of the uses in the insn. */ + note_uses (&PATTERN (insn), check_mem_read_use, bb_info); + + if (CALL_P (insn)) + { + insn_info->cannot_delete = true; + /* Const functions cannot do anything bad i.e. read memory, + however, they can read their parameters which may have been + pushed onto the stack. */ + if (CONST_OR_PURE_CALL_P (insn) && !pure_call_p (insn)) + { + insn_info_t i_ptr = active_local_stores; + insn_info_t last = NULL; + + if (dump_file) + fprintf (dump_file, "const call %d\n", INSN_UID (insn)); + + while (i_ptr) + { + store_info_t store_info = i_ptr->store_rec; + + /* Skip the clobbers. */ + while (!store_info->is_set) + store_info = store_info->next; + + /* Remove the frame related stores. */ + if (store_info->group_id >= 0 + && VEC_index (group_info_t, rtx_group_vec, store_info->group_id)->frame_related) + { + if (dump_file) + dump_insn_info ("removing from active", i_ptr); + + if (last) + last->next_local_store = i_ptr->next_local_store; + else + active_local_stores = i_ptr->next_local_store; + } + else + last = i_ptr; + i_ptr = i_ptr->next_local_store; + } + + insn_info->stack_read = true; + + return; + } + + /* Every other call, including pure functions may read memory. */ + add_wild_read (bb_info); + return; + } + + /* Assuming that there are sets in these insns, we cannot delete + them. */ + if ((GET_CODE (PATTERN (insn)) == CLOBBER) + || volatile_insn_p (PATTERN (insn)) + || (flag_non_call_exceptions && may_trap_p (PATTERN (insn))) + || (RTX_FRAME_RELATED_P (insn)) + || find_reg_note (insn, REG_FRAME_RELATED_EXPR, NULL_RTX)) + insn_info->cannot_delete = true; + + body = PATTERN (insn); + if (GET_CODE (body) == PARALLEL) + { + int i; + for (i = 0; i < XVECLEN (body, 0); i++) + mems_found += record_store (XVECEXP (body, 0, i), bb_info); + } + else + mems_found += record_store (body, bb_info); + + if (dump_file) + fprintf (dump_file, "mems_found = %d, cannot_delete = %s\n", + mems_found, insn_info->cannot_delete ? "true" : "false"); + + /* If we found some sets of mems, and the insn has not been marked + cannot delete, add it into the active_local_stores so that it can + be locally deleted if found dead. Otherwise mark it as cannot + delete. This simplifies the processing later. */ + if (mems_found == 1 && !insn_info->cannot_delete) + { + insn_info->next_local_store = active_local_stores; + active_local_stores = insn_info; + } + else + insn_info->cannot_delete = true; +} + + +/* Remove BASE from the set of active_local_stores. This is a + callback from cselib that is used to get rid of the stores in + active_local_stores. */ + +static void +remove_useless_values (cselib_val *base) +{ + insn_info_t insn_info = active_local_stores; + insn_info_t last = NULL; + + while (insn_info) + { + store_info_t store_info = insn_info->store_rec; + bool delete = false; + + /* If ANY of the store_infos match the cselib group that is + being deleted, then the insn can not be deleted. */ + while (store_info) + { + if ((store_info->group_id == -1) + && (store_info->cse_base == base)) + { + delete = true; + break; + } + store_info = store_info->next; + } + + if (delete) + { + if (last) + last->next_local_store = insn_info->next_local_store; + else + active_local_stores = insn_info->next_local_store; + free_store_info (insn_info); + } + else + last = insn_info; + + insn_info = insn_info->next_local_store; + } +} + + +/* Do all of step 1. */ + +static void +dse_step1 (void) +{ + basic_block bb; + + cselib_init (false); + all_blocks = BITMAP_ALLOC (NULL); + bitmap_set_bit (all_blocks, ENTRY_BLOCK); + bitmap_set_bit (all_blocks, EXIT_BLOCK); + + FOR_ALL_BB (bb) + { + insn_info_t ptr; + bb_info_t bb_info = pool_alloc (bb_info_pool); + + memset (bb_info, 0, sizeof (struct bb_info)); + bitmap_set_bit (all_blocks, bb->index); + + bb_table[bb->index] = bb_info; + cselib_discard_hook = remove_useless_values; + + if (bb->index >= NUM_FIXED_BLOCKS) + { + rtx insn; + + cse_store_info_pool + = create_alloc_pool ("cse_store_info_pool", + sizeof (struct store_info), 100); + active_local_stores = NULL; + cselib_clear_table (); + + /* Scan the insns. */ + FOR_BB_INSNS (bb, insn) + { + if (INSN_P (insn)) + scan_insn (bb_info, insn); + cselib_process_insn (insn); + } + + /* This is something of a hack, because the global algorithm + is supposed to take care of the case where stores go dead + at the end of the function. However, the global + algorithm must take a more conservative view of block + mode reads than the local alg does. So to get the case + where you have a store to the frame followed by a non + overlaping block more read, we look at the active local + stores at the end of the function and delete all of the + frame and spill based ones. */ + if (stores_off_frame_dead_at_return + && (EDGE_COUNT (bb->succs) == 0 + || (single_succ_p (bb) + && single_succ (bb) == EXIT_BLOCK_PTR + && ! current_function_calls_eh_return))) + { + insn_info_t i_ptr = active_local_stores; + while (i_ptr) + { + store_info_t store_info = i_ptr->store_rec; + + /* Skip the clobbers. */ + while (!store_info->is_set) + store_info = store_info->next; + if (store_info->alias_set) + delete_dead_store_insn (i_ptr); + else + if (store_info->group_id >= 0) + { + group_info_t group + = VEC_index (group_info_t, rtx_group_vec, store_info->group_id); + if (group->frame_related) + delete_dead_store_insn (i_ptr); + } + + i_ptr = i_ptr->next_local_store; + } + } + + /* Get rid of the loads that were discovered in + replace_read. Cselib is finished with this block. */ + while (deferred_change_list) + { + deferred_change_t next = deferred_change_list->next; + + /* There is no reason to validate this change. That was + done earlier. */ + *deferred_change_list->loc = deferred_change_list->reg; + pool_free (deferred_change_pool, deferred_change_list); + deferred_change_list = next; + } + + /* Get rid of all of the cselib based store_infos in this + block and mark the containing insns as not being + deletable. */ + ptr = bb_info->last_insn; + while (ptr) + { + if (ptr->contains_cselib_groups) + free_store_info (ptr); + ptr = ptr->prev_insn; + } + + free_alloc_pool (cse_store_info_pool); + } + } + + cselib_finish (); + htab_empty (rtx_group_table); +} + + +/*---------------------------------------------------------------------------- + Second step. + + Assign each byte position in the stores that we are going to + analyze globally to a position in the bitmaps. Returns true if + there are any bit postions assigned. +----------------------------------------------------------------------------*/ + +static void +dse_step2_init (void) +{ + unsigned int i; + group_info_t group; + + for (i = 0; VEC_iterate (group_info_t, rtx_group_vec, i, group); i++) + { + /* For all non stack related bases, we only consider a store to + be deletable if there are two or more stores for that + position. This is because it takes one store to make the + other store redundant. However, for the stores that are + stack related, we consider them if there is only one store + for the position. We do this because the stack related + stores can be deleted if their is no read between them and + the end of the function. + + To make this work in the current framework, we take the stack + related bases add all of the bits from store1 into store2. + This has the effect of making the eligible even if there is + only one store. */ + + if (stores_off_frame_dead_at_return && group->frame_related) + { + bitmap_ior_into (group->store2_n, group->store1_n); + bitmap_ior_into (group->store2_p, group->store1_p); + if (dump_file) + fprintf (dump_file, "group %d is frame related ", i); + } + + group->offset_map_size_n++; + group->offset_map_n = XNEWVEC (int, group->offset_map_size_n); + group->offset_map_size_p++; + group->offset_map_p = XNEWVEC (int, group->offset_map_size_p); + group->process_globally = false; + if (dump_file) + { + fprintf (dump_file, "group %d(%d+%d): ", i, + (int)bitmap_count_bits (group->store2_n), + (int)bitmap_count_bits (group->store2_p)); + bitmap_print (dump_file, group->store2_n, "n ", " "); + bitmap_print (dump_file, group->store2_p, "p ", "\n"); + } + } +} + + +/* Init the offset tables for the normal case. */ + +static bool +dse_step2_nospill (void) +{ + unsigned int i; + group_info_t group; + /* Position 0 is unused because 0 is used in the maps to mean + unused. */ + current_position = 1; + + for (i = 0; VEC_iterate (group_info_t, rtx_group_vec, i, group); i++) + { + bitmap_iterator bi; + unsigned int j; + + if (group == clear_alias_group) + continue; + + memset (group->offset_map_n, 0, sizeof(int) * group->offset_map_size_n); + memset (group->offset_map_p, 0, sizeof(int) * group->offset_map_size_p); + bitmap_clear (group->group_kill); + + EXECUTE_IF_SET_IN_BITMAP (group->store2_n, 0, j, bi) + { + bitmap_set_bit (group->group_kill, current_position); + group->offset_map_n[j] = current_position++; + group->process_globally = true; + } + EXECUTE_IF_SET_IN_BITMAP (group->store2_p, 0, j, bi) + { + bitmap_set_bit (group->group_kill, current_position); + group->offset_map_p[j] = current_position++; + group->process_globally = true; + } + } + return current_position != 1; +} + + +/* Init the offset tables for the spill case. */ + +static bool +dse_step2_spill (void) +{ + unsigned int j; + group_info_t group = clear_alias_group; + bitmap_iterator bi; + + /* Position 0 is unused because 0 is used in the maps to mean + unused. */ + current_position = 1; + + if (dump_file) + { + bitmap_print (dump_file, clear_alias_sets, + "clear alias sets ", "\n"); + bitmap_print (dump_file, disqualified_clear_alias_sets, + "disqualified clear alias sets ", "\n"); + } + + memset (group->offset_map_n, 0, sizeof(int) * group->offset_map_size_n); + memset (group->offset_map_p, 0, sizeof(int) * group->offset_map_size_p); + bitmap_clear (group->group_kill); + + /* Remove the disqualified positions from the store2_p set. */ + bitmap_and_compl_into (group->store2_p, disqualified_clear_alias_sets); + + /* We do not need to process the store2_n set because + alias_sets are always positive. */ + EXECUTE_IF_SET_IN_BITMAP (group->store2_p, 0, j, bi) + { + bitmap_set_bit (group->group_kill, current_position); + group->offset_map_p[j] = current_position++; + group->process_globally = true; + } + + return current_position != 1; +} + + + +/*---------------------------------------------------------------------------- + Third step. + + Build the bit vectors for the transfer functions. +----------------------------------------------------------------------------*/ + + +/* Note that this is NOT a general purpose function. Any mem that has + an alias set registered here expected to be COMPLETELY unaliased: + i.e it's addresses are not and need not be examined. + + It is known that all references to this address will have this + alias set and there are NO other references to this address in the + function. + + Currently the only place that is known to be clean enough to use + this interface is the code that assigns the spill locations. + + All of the mems that have alias_sets registered are subjected to a + very powerful form of dse where function calls, volatile reads and + writes, and reads from random location are not taken into account. + + It is also assumed that these locations go dead when the function + returns. This assumption could be relaxed if there were found to + be places that this assumption was not correct. + + The MODE is passed in and saved. The mode of each load or store to + a mem with ALIAS_SET is checked against MEM. If the size of that + load or store is different from MODE, processing is halted on this + alias set. For the vast majority of aliases sets, all of the loads + and stores will use the same mode. But vectors are treated + differently: the alias set is established for the entire vector, + but reload will insert loads and stores for individual elements and + we do not necessarily have the information to track those separate + elements. So when we see a mode mismatch, we just bail. */ + + +void +dse_record_singleton_alias_set (HOST_WIDE_INT alias_set, + enum machine_mode mode) +{ + struct clear_alias_mode_holder tmp_holder; + struct clear_alias_mode_holder *entry; + void **slot; + + /* If we are not going to run dse, we need to return now or there + will be problems with allocating the bitmaps. */ + if ((!gate_dse()) || !alias_set) + return; + + if (!clear_alias_sets) + { + clear_alias_sets = BITMAP_ALLOC (NULL); + disqualified_clear_alias_sets = BITMAP_ALLOC (NULL); + clear_alias_mode_table = htab_create (11, clear_alias_mode_hash, + clear_alias_mode_eq, NULL); + clear_alias_mode_pool = create_alloc_pool ("clear_alias_mode_pool", + sizeof (struct clear_alias_mode_holder), 100); + } + + bitmap_set_bit (clear_alias_sets, alias_set); + + tmp_holder.alias_set = alias_set; + + slot = htab_find_slot (clear_alias_mode_table, &tmp_holder, INSERT); + gcc_assert (*slot == NULL); + + *slot = entry = pool_alloc (clear_alias_mode_pool); + entry->alias_set = alias_set; + entry->mode = mode; +} + + +/* Remove ALIAS_SET from the sets of stack slots being considered. */ + +void +dse_invalidate_singleton_alias_set (HOST_WIDE_INT alias_set) +{ + if ((!gate_dse()) || !alias_set) + return; + + bitmap_clear_bit (clear_alias_sets, alias_set); +} + + +/* Look up the bitmap index for OFFSET in GROUP_INFO. If it is not + there, return 0. */ + +static int +get_bitmap_index (group_info_t group_info, HOST_WIDE_INT offset) +{ + if (offset < 0) + { + HOST_WIDE_INT offset_p = -offset; + if (offset_p >= group_info->offset_map_size_n) + return 0; + return group_info->offset_map_n[offset_p]; + } + else + { + if (offset >= group_info->offset_map_size_p) + return 0; + return group_info->offset_map_p[offset]; + } +} + + +/* Process the STORE_INFOs into the bitmaps into GEN and KILL. KILL + may be NULL. */ + +static void +scan_stores_nospill (store_info_t store_info, bitmap gen, bitmap kill) +{ + while (store_info) + { + HOST_WIDE_INT i; + group_info_t group_info + = VEC_index (group_info_t, rtx_group_vec, store_info->group_id); + if (group_info->process_globally) + for (i = store_info->begin; i < store_info->end; i++) + { + int index = get_bitmap_index (group_info, i); + if (index != 0) + { + bitmap_set_bit (gen, index); + if (kill) + bitmap_clear_bit (kill, index); + } + } + store_info = store_info->next; + } +} + + +/* Process the STORE_INFOs into the bitmaps into GEN and KILL. KILL + may be NULL. */ + +static void +scan_stores_spill (store_info_t store_info, bitmap gen, bitmap kill) +{ + while (store_info) + { + if (store_info->alias_set) + { + int index = get_bitmap_index (clear_alias_group, + store_info->alias_set); + if (index != 0) + { + bitmap_set_bit (gen, index); + if (kill) + bitmap_clear_bit (kill, index); + } + } + store_info = store_info->next; + } +} + + +/* Process the READ_INFOs into the bitmaps into GEN and KILL. KILL + may be NULL. */ + +static void +scan_reads_nospill (insn_info_t insn_info, bitmap gen, bitmap kill) +{ + read_info_t read_info = insn_info->read_rec; + int i; + group_info_t group; + + /* For const function calls kill the stack related stores. */ + if (insn_info->stack_read) + { + for (i = 0; VEC_iterate (group_info_t, rtx_group_vec, i, group); i++) + if (group->process_globally && group->frame_related) + { + if (kill) + bitmap_ior_into (kill, group->group_kill); + bitmap_and_compl_into (gen, group->group_kill); + } + } + + while (read_info) + { + for (i = 0; VEC_iterate (group_info_t, rtx_group_vec, i, group); i++) + { + if (group->process_globally) + { + if (i == read_info->group_id) + { + if (read_info->begin > read_info->end) + { + /* Begin > end for block mode reads. */ + if (kill) + bitmap_ior_into (kill, group->group_kill); + bitmap_and_compl_into (gen, group->group_kill); + } + else + { + /* The groups are the same, just process the + offsets. */ + HOST_WIDE_INT j; + for (j = read_info->begin; j < read_info->end; j++) + { + int index = get_bitmap_index (group, j); + if (index != 0) + { + if (kill) + bitmap_set_bit (kill, index); + bitmap_clear_bit (gen, index); + } + } + } + } + else + { + /* The groups are different, if the alias sets + conflict, clear the entire group. We only need + to apply this test if the read_info is a cselib + read. Anything with a constant base cannot alias + something else with a different constant + base. */ + if ((read_info->group_id < 0) + && canon_true_dependence (group->base_mem, + QImode, + group->canon_base_mem, + read_info->mem, rtx_varies_p)) + { + if (kill) + bitmap_ior_into (kill, group->group_kill); + bitmap_and_compl_into (gen, group->group_kill); + } + } + } + } + + read_info = read_info->next; + } +} + +/* Process the READ_INFOs into the bitmaps into GEN and KILL. KILL + may be NULL. */ + +static void +scan_reads_spill (read_info_t read_info, bitmap gen, bitmap kill) +{ + while (read_info) + { + if (read_info->alias_set) + { + int index = get_bitmap_index (clear_alias_group, + read_info->alias_set); + if (index != 0) + { + if (kill) + bitmap_set_bit (kill, index); + bitmap_clear_bit (gen, index); + } + } + + read_info = read_info->next; + } +} + + +/* Return the insn in BB_INFO before the first wild read or if there + are no wild reads in the block, return the last insn. */ + +static insn_info_t +find_insn_before_first_wild_read (bb_info_t bb_info) +{ + insn_info_t insn_info = bb_info->last_insn; + insn_info_t last_wild_read = NULL; + + while (insn_info) + { + if (insn_info->wild_read) + { + last_wild_read = insn_info->prev_insn; + /* Block starts with wild read. */ + if (!last_wild_read) + return NULL; + } + + insn_info = insn_info->prev_insn; + } + + if (last_wild_read) + return last_wild_read; + else + return bb_info->last_insn; +} + + +/* Scan the insns in BB_INFO starting at PTR and going to the top of + the block in order to build the gen and kill sets for the block. + We start at ptr which may be the last insn in the block or may be + the first insn with a wild read. In the latter case we are able to + skip the rest of the block because it just does not matter: + anything that happens is hidden by the wild read. */ + +static void +dse_step3_scan (bool for_spills, basic_block bb) +{ + bb_info_t bb_info = bb_table[bb->index]; + insn_info_t insn_info; + + if (for_spills) + /* There are no wild reads in the spill case. */ + insn_info = bb_info->last_insn; + else + insn_info = find_insn_before_first_wild_read (bb_info); + + /* In the spill case or in the no_spill case if there is no wild + read in the block, we will need a kill set. */ + if (insn_info == bb_info->last_insn) + { + if (bb_info->kill) + bitmap_clear (bb_info->kill); + else + bb_info->kill = BITMAP_ALLOC (NULL); + } + else + if (bb_info->kill) + BITMAP_FREE (bb_info->kill); + + while (insn_info) + { + /* There may have been code deleted by the dce pass run before + this phase. */ + if (insn_info->insn && INSN_P (insn_info->insn)) + { + /* Process the read(s) last. */ + if (for_spills) + { + scan_stores_spill (insn_info->store_rec, bb_info->gen, bb_info->kill); + scan_reads_spill (insn_info->read_rec, bb_info->gen, bb_info->kill); + } + else + { + scan_stores_nospill (insn_info->store_rec, bb_info->gen, bb_info->kill); + scan_reads_nospill (insn_info, bb_info->gen, bb_info->kill); + } + } + + insn_info = insn_info->prev_insn; + } +} + + +/* Set the gen set of the exit block, and also any block with no + successors that does not have a wild read. */ + +static void +dse_step3_exit_block_scan (bb_info_t bb_info) +{ + /* The gen set is all 0's for the exit block except for the + frame_pointer_group. */ + + if (stores_off_frame_dead_at_return) + { + unsigned int i; + group_info_t group; + + for (i = 0; VEC_iterate (group_info_t, rtx_group_vec, i, group); i++) + { + if (group->process_globally && group->frame_related) + bitmap_ior_into (bb_info->gen, group->group_kill); + } + } +} + + +/* Find all of the blocks that are not backwards reachable from the + exit block or any block with no successors (BB). These are the + infinite loops or infinite self loops. These blocks will still + have their bits set in UNREACHABLE_BLOCKS. */ + +static void +mark_reachable_blocks (sbitmap unreachable_blocks, basic_block bb) +{ + edge e; + edge_iterator ei; + + if (TEST_BIT (unreachable_blocks, bb->index)) + { + RESET_BIT (unreachable_blocks, bb->index); + FOR_EACH_EDGE (e, ei, bb->preds) + { + mark_reachable_blocks (unreachable_blocks, e->src); + } + } +} + +/* Build the transfer functions for the function. */ + +static void +dse_step3 (bool for_spills) +{ + basic_block bb; + sbitmap unreachable_blocks = sbitmap_alloc (last_basic_block); + sbitmap_iterator sbi; + bitmap all_ones = NULL; + unsigned int i; + + sbitmap_ones (unreachable_blocks); + + FOR_ALL_BB (bb) + { + bb_info_t bb_info = bb_table[bb->index]; + if (bb_info->gen) + bitmap_clear (bb_info->gen); + else + bb_info->gen = BITMAP_ALLOC (NULL); + + if (bb->index == ENTRY_BLOCK) + ; + else if (bb->index == EXIT_BLOCK) + dse_step3_exit_block_scan (bb_info); + else + dse_step3_scan (for_spills, bb); + if (EDGE_COUNT (bb->succs) == 0) + mark_reachable_blocks (unreachable_blocks, bb); + + /* If this is the second time dataflow is run, delete the old + sets. */ + if (bb_info->in) + BITMAP_FREE (bb_info->in); + if (bb_info->out) + BITMAP_FREE (bb_info->out); + } + + /* For any block in an infinite loop, we must initialize the out set + to all ones. This could be expensive, but almost never occurs in + practice. However, it is common in regression tests. */ + EXECUTE_IF_SET_IN_SBITMAP (unreachable_blocks, 0, i, sbi) + { + if (bitmap_bit_p (all_blocks, i)) + { + bb_info_t bb_info = bb_table[i]; + if (!all_ones) + { + unsigned int j; + group_info_t group; + + all_ones = BITMAP_ALLOC (NULL); + for (j = 0; VEC_iterate (group_info_t, rtx_group_vec, j, group); j++) + bitmap_ior_into (all_ones, group->group_kill); + } + if (!bb_info->out) + { + bb_info->out = BITMAP_ALLOC (NULL); + bitmap_copy (bb_info->out, all_ones); + } + } + } + + if (all_ones) + BITMAP_FREE (all_ones); + sbitmap_free (unreachable_blocks); +} + + + +/*---------------------------------------------------------------------------- + Fourth step. + + Solve the bitvector equations. +----------------------------------------------------------------------------*/ + + +/* Confluence function for blocks with no successors. Create an out + set from the gen set of the exit block. This block logically has + the exit block as a successor. */ + + + +static void +dse_confluence_0 (basic_block bb) +{ + bb_info_t bb_info = bb_table[bb->index]; + + if (bb->index == EXIT_BLOCK) + return; + + if (!bb_info->out) + { + bb_info->out = BITMAP_ALLOC (NULL); + bitmap_copy (bb_info->out, bb_table[EXIT_BLOCK]->gen); + } +} + +/* Propagate the information from the in set of the dest of E to the + out set of the src of E. If the various in or out sets are not + there, that means they are all ones. */ + +static void +dse_confluence_n (edge e) +{ + bb_info_t src_info = bb_table[e->src->index]; + bb_info_t dest_info = bb_table[e->dest->index]; + + if (dest_info->in) + { + if (src_info->out) + bitmap_and_into (src_info->out, dest_info->in); + else + { + src_info->out = BITMAP_ALLOC (NULL); + bitmap_copy (src_info->out, dest_info->in); + } + } +} + + +/* Propagate the info from the out to the in set of BB_INDEX's basic + block. There are three cases: + + 1) The block has no kill set. In this case the kill set is all + ones. It does not matter what the out set of the block is, none of + the info can reach the top. The only thing that reaches the top is + the gen set and we just copy the set. + + 2) There is a kill set but no out set and bb has successors. In + this case we just return. Eventually an out set will be created and + it is better to wait than to create a set of ones. + + 3) There is both a kill and out set. We apply the obvious transfer + function. +*/ + +static bool +dse_transfer_function (int bb_index) +{ + bb_info_t bb_info = bb_table[bb_index]; + + if (bb_info->kill) + { + if (bb_info->out) + { + /* Case 3 above. */ + if (bb_info->in) + return bitmap_ior_and_compl (bb_info->in, bb_info->gen, + bb_info->out, bb_info->kill); + else + { + bb_info->in = BITMAP_ALLOC (NULL); + bitmap_ior_and_compl (bb_info->in, bb_info->gen, + bb_info->out, bb_info->kill); + return true; + } + } + else + /* Case 2 above. */ + return false; + } + else + { + /* Case 1 above. If there is already an in set, nothing + happens. */ + if (bb_info->in) + return false; + else + { + bb_info->in = BITMAP_ALLOC (NULL); + bitmap_copy (bb_info->in, bb_info->gen); + return true; + } + } +} + +/* Solve the dataflow equations. */ + +static void +dse_step4 (void) +{ + df_simple_dataflow (DF_BACKWARD, NULL, dse_confluence_0, + dse_confluence_n, dse_transfer_function, + all_blocks, df_get_postorder (DF_BACKWARD), + df_get_n_blocks (DF_BACKWARD)); + if (dump_file) + { + basic_block bb; + + fprintf (dump_file, "\n\n*** Global dataflow info after analysis.\n"); + FOR_ALL_BB (bb) + { + bb_info_t bb_info = bb_table[bb->index]; + + df_print_bb_index (bb, dump_file); + if (bb_info->in) + bitmap_print (dump_file, bb_info->in, " in: ", "\n"); + else + fprintf (dump_file, " in: *MISSING*\n"); + if (bb_info->gen) + bitmap_print (dump_file, bb_info->gen, " gen: ", "\n"); + else + fprintf (dump_file, " gen: *MISSING*\n"); + if (bb_info->kill) + bitmap_print (dump_file, bb_info->kill, " kill: ", "\n"); + else + fprintf (dump_file, " kill: *MISSING*\n"); + if (bb_info->out) + bitmap_print (dump_file, bb_info->out, " out: ", "\n"); + else + fprintf (dump_file, " out: *MISSING*\n\n"); + } + } +} + + + +/*---------------------------------------------------------------------------- + Fifth step. + + Delete the stores that can only be deleted using the global informantion. +----------------------------------------------------------------------------*/ + + +static void +dse_step5_nospill (void) +{ + basic_block bb; + FOR_EACH_BB (bb) + { + bb_info_t bb_info = bb_table[bb->index]; + insn_info_t insn_info = bb_info->last_insn; + bitmap v = bb_info->out; + + while (insn_info) + { + bool deleted = false; + if (dump_file && insn_info->insn) + { + fprintf (dump_file, "starting to process insn %d\n", + INSN_UID (insn_info->insn)); + bitmap_print (dump_file, v, " v: ", "\n"); + } + + /* There may have been code deleted by the dce pass run before + this phase. */ + if (insn_info->insn + && INSN_P (insn_info->insn) + && (!insn_info->cannot_delete) + && (!bitmap_empty_p (v))) + { + store_info_t store_info = insn_info->store_rec; + + /* Try to delete the current insn. */ + deleted = true; + + /* Skip the clobbers. */ + while (!store_info->is_set) + store_info = store_info->next; + + if (store_info->alias_set) + deleted = false; + else + { + HOST_WIDE_INT i; + group_info_t group_info + = VEC_index (group_info_t, rtx_group_vec, store_info->group_id); + + for (i = store_info->begin; i < store_info->end; i++) + { + int index = get_bitmap_index (group_info, i); + + if (dump_file) + fprintf (dump_file, "i = %d, index = %d\n", (int)i, index); + if (index == 0 || !bitmap_bit_p (v, index)) + { + if (dump_file) + fprintf (dump_file, "failing at i = %d\n", (int)i); + deleted = false; + break; + } + } + } + if (deleted) + { + if (dbg_cnt (dse)) + { + check_for_inc_dec (insn_info->insn); + delete_insn (insn_info->insn); + insn_info->insn = NULL; + globally_deleted++; + } + } + } + /* We do want to process the local info if the insn was + deleted. For insntance, if the insn did a wild read, we + no longer need to trash the info. */ + if (insn_info->insn + && INSN_P (insn_info->insn) + && (!deleted)) + { + scan_stores_nospill (insn_info->store_rec, v, NULL); + if (insn_info->wild_read) + { + if (dump_file) + fprintf (dump_file, "wild read\n"); + bitmap_clear (v); + } + else if (insn_info->read_rec) + { + if (dump_file) + fprintf (dump_file, "regular read\n"); + scan_reads_nospill (insn_info, v, NULL); + } + } + + insn_info = insn_info->prev_insn; + } + } +} + + +static void +dse_step5_spill (void) +{ + basic_block bb; + FOR_EACH_BB (bb) + { + bb_info_t bb_info = bb_table[bb->index]; + insn_info_t insn_info = bb_info->last_insn; + bitmap v = bb_info->out; + + while (insn_info) + { + bool deleted = false; + /* There may have been code deleted by the dce pass run before + this phase. */ + if (insn_info->insn + && INSN_P (insn_info->insn) + && (!insn_info->cannot_delete) + && (!bitmap_empty_p (v))) + { + /* Try to delete the current insn. */ + store_info_t store_info = insn_info->store_rec; + deleted = true; + + while (store_info) + { + if (store_info->alias_set) + { + int index = get_bitmap_index (clear_alias_group, + store_info->alias_set); + if (index == 0 || !bitmap_bit_p (v, index)) + { + deleted = false; + break; + } + } + else + deleted = false; + store_info = store_info->next; + } + if (deleted && dbg_cnt (dse)) + { + if (dump_file) + fprintf (dump_file, "Spill deleting insn %d\n", + INSN_UID (insn_info->insn)); + check_for_inc_dec (insn_info->insn); + delete_insn (insn_info->insn); + spill_deleted++; + insn_info->insn = NULL; + } + } + + if (insn_info->insn + && INSN_P (insn_info->insn) + && (!deleted)) + { + scan_stores_spill (insn_info->store_rec, v, NULL); + scan_reads_spill (insn_info->read_rec, v, NULL); + } + + insn_info = insn_info->prev_insn; + } + } +} + + + +/*---------------------------------------------------------------------------- + Sixth step. + + Destroy everything left standing. +----------------------------------------------------------------------------*/ + +static void +dse_step6 (bool global_done) +{ + unsigned int i; + group_info_t group; + basic_block bb; + + if (global_done) + { + for (i = 0; VEC_iterate (group_info_t, rtx_group_vec, i, group); i++) + { + free (group->offset_map_n); + free (group->offset_map_p); + BITMAP_FREE (group->store1_n); + BITMAP_FREE (group->store1_p); + BITMAP_FREE (group->store2_n); + BITMAP_FREE (group->store2_p); + BITMAP_FREE (group->group_kill); + } + + FOR_ALL_BB (bb) + { + bb_info_t bb_info = bb_table[bb->index]; + BITMAP_FREE (bb_info->gen); + if (bb_info->kill) + BITMAP_FREE (bb_info->kill); + if (bb_info->in) + BITMAP_FREE (bb_info->in); + if (bb_info->out) + BITMAP_FREE (bb_info->out); + } + } + else + { + for (i = 0; VEC_iterate (group_info_t, rtx_group_vec, i, group); i++) + { + BITMAP_FREE (group->store1_n); + BITMAP_FREE (group->store1_p); + BITMAP_FREE (group->store2_n); + BITMAP_FREE (group->store2_p); + BITMAP_FREE (group->group_kill); + } + } + + if (clear_alias_sets) + { + BITMAP_FREE (clear_alias_sets); + BITMAP_FREE (disqualified_clear_alias_sets); + free_alloc_pool (clear_alias_mode_pool); + htab_delete (clear_alias_mode_table); + } + + end_alias_analysis (); + free (bb_table); + htab_delete (rtx_group_table); + VEC_free (group_info_t, heap, rtx_group_vec); + BITMAP_FREE (all_blocks); + BITMAP_FREE (scratch); + + free_alloc_pool (rtx_store_info_pool); + free_alloc_pool (read_info_pool); + free_alloc_pool (insn_info_pool); + free_alloc_pool (bb_info_pool); + free_alloc_pool (rtx_group_info_pool); + free_alloc_pool (deferred_change_pool); +} + + + +/* ------------------------------------------------------------------------- + DSE + ------------------------------------------------------------------------- */ + +/* Callback for running pass_rtl_dse. */ + +static unsigned int +rest_of_handle_dse (void) +{ + bool did_global = false; + + df_set_flags (DF_DEFER_INSN_RESCAN); + + dse_step0 (); + dse_step1 (); + dse_step2_init (); + if (dse_step2_nospill ()) + { + df_set_flags (DF_LR_RUN_DCE); + df_analyze (); + did_global = true; + if (dump_file) + fprintf (dump_file, "doing global processing\n"); + dse_step3 (false); + dse_step4 (); + dse_step5_nospill (); + } + + /* For the instance of dse that runs after reload, we make a special + pass to process the spills. These are special in that they are + totally transparent, i.e, there is no aliasing issues that need + to be considered. This means that the wild reads that kill + everything else do not apply here. */ + if (clear_alias_sets && dse_step2_spill ()) + { + if (!did_global) + { + df_set_flags (DF_LR_RUN_DCE); + df_analyze (); + } + did_global = true; + if (dump_file) + fprintf (dump_file, "doing global spill processing\n"); + dse_step3 (true); + dse_step4 (); + dse_step5_spill (); + } + + dse_step6 (did_global); + + if (dump_file) + fprintf (dump_file, "dse: local deletions = %d, global deletions = %d, spill deletions = %d\n", + locally_deleted, globally_deleted, spill_deleted); + return 0; +} + +static bool +gate_dse (void) +{ + return optimize > 0 && flag_dse; +} + +struct tree_opt_pass pass_rtl_dse1 = +{ + "dse1", /* name */ + gate_dse, /* gate */ + rest_of_handle_dse, /* execute */ + NULL, /* sub */ + NULL, /* next */ + 0, /* static_pass_number */ + TV_DSE1, /* tv_id */ + 0, /* properties_required */ + 0, /* properties_provided */ + 0, /* properties_destroyed */ + 0, /* todo_flags_start */ + TODO_dump_func | + TODO_df_finish | + TODO_ggc_collect, /* todo_flags_finish */ + 'w' /* letter */ +}; + +struct tree_opt_pass pass_rtl_dse2 = +{ + "dse2", /* name */ + gate_dse, /* gate */ + rest_of_handle_dse, /* execute */ + NULL, /* sub */ + NULL, /* next */ + 0, /* static_pass_number */ + TV_DSE2, /* tv_id */ + 0, /* properties_required */ + 0, /* properties_provided */ + 0, /* properties_destroyed */ + 0, /* todo_flags_start */ + TODO_dump_func | + TODO_df_finish | + TODO_ggc_collect, /* todo_flags_finish */ + 'w' /* letter */ +}; + -- cgit v1.1