| /* RTL dead store elimination. |
| Copyright (C) 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc. |
| |
| Contributed by Richard Sandiford <rsandifor@codesourcery.com> |
| and Kenneth Zadeck <zadeck@naturalbridge.com> |
| |
| This file is part of GCC. |
| |
| GCC is free software; you can redistribute it and/or modify it under |
| the terms of the GNU General Public License as published by the Free |
| Software Foundation; either version 3, or (at your option) any later |
| version. |
| |
| GCC is distributed in the hope that it will be useful, but WITHOUT ANY |
| WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GCC; see the file COPYING3. If not see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #undef BASELINE |
| |
| #include "config.h" |
| #include "system.h" |
| #include "coretypes.h" |
| #include "hashtab.h" |
| #include "tm.h" |
| #include "rtl.h" |
| #include "tree.h" |
| #include "tm_p.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 "optabs.h" |
| #include "dbgcnt.h" |
| #include "target.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) Delete insns that store the same value as preceeding store |
| where the earlier store couldn't be eliminated. |
| |
| 7) 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 accommodate 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 information 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 |
| required 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; |
| |
| /* False if a single HOST_WIDE_INT bitmap is used for positions_needed. */ |
| bool is_large; |
| |
| /* 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; |
| |
| /* Canonized MEM address for use by canon_true_dependence. */ |
| rtx mem_addr; |
| |
| /* If this is non-zero, it is the alias set of a spill location. */ |
| alias_set_type alias_set; |
| |
| /* The offset of the first and byte before the last byte associated |
| with the operation. */ |
| HOST_WIDE_INT begin, end; |
| |
| union |
| { |
| /* A 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. This is used if IS_LARGE is false. */ |
| unsigned HOST_WIDE_INT small_bitmask; |
| |
| struct |
| { |
| /* A bitmap with one bit per byte. Cleared bit means the position |
| is needed. Used if IS_LARGE is false. */ |
| bitmap bitmap; |
| |
| /* Number of set bits (i.e. unneeded bytes) in BITMAP. If it is |
| equal to END - BEGIN, the whole store is unused. */ |
| int count; |
| } large; |
| } 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; |
| |
| /* If rhs is or holds a constant, this contains that constant, |
| otherwise NULL. */ |
| rtx const_rhs; |
| |
| /* Set if this store stores the same constant value as REDUNDANT_REASON |
| insn stored. These aren't eliminated early, because doing that |
| might prevent the earlier larger store to be eliminated. */ |
| struct insn_info *redundant_reason; |
| }; |
| |
| /* Return a bitmask with the first N low bits set. */ |
| |
| static unsigned HOST_WIDE_INT |
| lowpart_bitmask (int n) |
| { |
| unsigned HOST_WIDE_INT mask = ~(unsigned HOST_WIDE_INT) 0; |
| return mask >> (HOST_BITS_PER_WIDE_INT - n); |
| } |
| |
| 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. */ |
| alias_set_type 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 only used for the processing of const functions. |
| These functions cannot read memory, but they can read the stack |
| because that is where they may get their parms. We need to be |
| this conservative because, like the store motion pass, we don't |
| consider CALL_INSN_FUNCTION_USAGE when processing call insns. |
| Moreover, we need to distinguish two cases: |
| 1. Before reload (register elimination), the stores related to |
| outgoing arguments are stack pointer based and thus deemed |
| of non-constant base in this pass. This requires special |
| handling but also means that the frame pointer based stores |
| need not be killed upon encountering a const function call. |
| 2. After reload, the stores related to outgoing arguments can be |
| either stack pointer or hard frame pointer based. This means |
| that we have no other choice than also killing all the frame |
| pointer based stores upon encountering a const function call. |
| This field is set after reload for const function calls. Having |
| this set is less severe than a wild read, it just means that all |
| the frame related stores are killed rather than all the stores. */ |
| bool frame_read; |
| |
| /* This field is only used for the processing of const functions. |
| It is set if the insn may contain a stack pointer based store. */ |
| bool stack_pointer_based; |
| |
| /* 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 provide 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 traversal 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 following 4 bitvectors hold information about which positions |
| of which stores are live or dead. They are indexed by |
| get_bitmap_index. */ |
| |
| /* 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; |
| |
| /* The following bitvector is indexed by the reg number. It |
| contains the set of regs that are live at the current instruction |
| being processed. While it contains info for all of the |
| registers, only the pseudos are actually examined. It is used to |
| assure that shift sequences that are inserted do not accidently |
| clobber live hard regs. */ |
| bitmap regs_live; |
| }; |
| |
| 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; |
| |
| /* 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; |
| |
| /* A mem wrapped around the base pointer for the group in order to |
| do read dependency. */ |
| rtx base_mem; |
| |
| /* Canonized version of base_mem's address. */ |
| rtx canon_base_addr; |
| |
| /* These two sets of two bitmaps are used to keep track of how many |
| stores are actually referencing that position from this base. We |
| only do this for rtx bases as this will be used to assign |
| positions 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 positions in this bitmap have the same assignments as the in, |
| out, gen and kill bitmaps. This bitmap is all zeros except for |
| the positions that are occupied by stores for this group. */ |
| bitmap group_kill; |
| |
| /* The offset_map is used to map the offsets from this base into |
| positions 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; |
| typedef const struct group_info *const_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 |
| { |
| alias_set_type alias_set; |
| enum machine_mode mode; |
| }; |
| |
| static alloc_pool clear_alias_mode_pool; |
| |
| /* This is true except if cfun->stdarg -- i.e. we cannot do |
| this for vararg functions because they play games with the frame. */ |
| 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); |
| static bool gate_dse1 (void); |
| static bool gate_dse2 (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 (alias_set_type 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 (struct clear_alias_mode_holder *) *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 = |
| (group_info_t) 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 = (group_info_t) 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_addr = canon_rtx (base); |
| 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 = !cfun->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 accommodate 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->is_large) |
| BITMAP_FREE (store_info->positions_needed.large.bitmap); |
| 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); |
| emit_insn_before (gen_rtx_SET (Pmode, r1, |
| gen_rtx_PLUS (Pmode, r1, c)), |
| data->insn); |
| return -1; |
| } |
| |
| case PRE_DEC: |
| case POST_DEC: |
| { |
| rtx r1 = XEXP (x, 0); |
| rtx c = gen_int_mode (Pmode, -data->size); |
| emit_insn_before (gen_rtx_SET (Pmode, r1, |
| gen_rtx_PLUS (Pmode, r1, c)), |
| data->insn); |
| return -1; |
| } |
| |
| case PRE_MODIFY: |
| case POST_MODIFY: |
| { |
| /* We can reuse the add because we are about to delete the |
| insn that contained it. */ |
| rtx add = XEXP (x, 0); |
| rtx r1 = XEXP (add, 0); |
| emit_insn_before (gen_rtx_SET (Pmode, r1, add), data->insn); |
| 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 (x != NULL_RTX && MEM_P (x)) |
| { |
| 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 + width < MAX_OFFSET) |
| for (i=offset; i<offset+width; i++) |
| { |
| bitmap store1; |
| bitmap store2; |
| int ai; |
| if (i < 0) |
| { |
| store1 = group->store1_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 behave |
| as a constant over the life of a function. This is equivalent to |
| !rtx_varies_p for memory addresses. */ |
| |
| 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, |
| alias_set_type *alias_set_out, |
| int *group_id, |
| HOST_WIDE_INT *offset, |
| cselib_val **base) |
| { |
| rtx mem_address = XEXP (mem, 0); |
| rtx expanded_address, address; |
| int expanded; |
| |
| /* 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. */ |
| alias_set_type 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"); |
| } |
| |
| /* First see if just canon_rtx (mem_address) is const or frame, |
| if not, try cselib_expand_value_rtx and call canon_rtx on that. */ |
| address = NULL_RTX; |
| for (expanded = 0; expanded < 2; expanded++) |
| { |
| if (expanded) |
| { |
| /* 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 address from first |
| iteration. */ |
| if (!expanded_address) |
| break; |
| } |
| else |
| expanded_address = mem_address; |
| |
| /* Split the address into canonical BASE + OFFSET terms. */ |
| address = canon_rtx (expanded_address); |
| |
| *offset = 0; |
| |
| if (dump_file) |
| { |
| if (expanded) |
| { |
| 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; |
| return true; |
| } |
| } |
| |
| *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; |
| store_info->const_rhs = NULL; |
| |
| ptr = ptr->next_local_store; |
| } |
| } |
| |
| |
| /* Mark byte POS bytes from the beginning of store S_INFO as unneeded. */ |
| |
| static inline void |
| set_position_unneeded (store_info_t s_info, int pos) |
| { |
| if (__builtin_expect (s_info->is_large, false)) |
| { |
| if (!bitmap_bit_p (s_info->positions_needed.large.bitmap, pos)) |
| { |
| s_info->positions_needed.large.count++; |
| bitmap_set_bit (s_info->positions_needed.large.bitmap, pos); |
| } |
| } |
| else |
| s_info->positions_needed.small_bitmask |
| &= ~(((unsigned HOST_WIDE_INT) 1) << pos); |
| } |
| |
| /* Mark the whole store S_INFO as unneeded. */ |
| |
| static inline void |
| set_all_positions_unneeded (store_info_t s_info) |
| { |
| if (__builtin_expect (s_info->is_large, false)) |
| { |
| int pos, end = s_info->end - s_info->begin; |
| for (pos = 0; pos < end; pos++) |
| bitmap_set_bit (s_info->positions_needed.large.bitmap, pos); |
| s_info->positions_needed.large.count = end; |
| } |
| else |
| s_info->positions_needed.small_bitmask = (unsigned HOST_WIDE_INT) 0; |
| } |
| |
| /* Return TRUE if any bytes from S_INFO store are needed. */ |
| |
| static inline bool |
| any_positions_needed_p (store_info_t s_info) |
| { |
| if (__builtin_expect (s_info->is_large, false)) |
| return (s_info->positions_needed.large.count |
| < s_info->end - s_info->begin); |
| else |
| return (s_info->positions_needed.small_bitmask |
| != (unsigned HOST_WIDE_INT) 0); |
| } |
| |
| /* Return TRUE if all bytes START through START+WIDTH-1 from S_INFO |
| store are needed. */ |
| |
| static inline bool |
| all_positions_needed_p (store_info_t s_info, int start, int width) |
| { |
| if (__builtin_expect (s_info->is_large, false)) |
| { |
| int end = start + width; |
| while (start < end) |
| if (bitmap_bit_p (s_info->positions_needed.large.bitmap, start++)) |
| return false; |
| return true; |
| } |
| else |
| { |
| unsigned HOST_WIDE_INT mask = lowpart_bitmask (width) << start; |
| return (s_info->positions_needed.small_bitmask & mask) == mask; |
| } |
| } |
| |
| |
| static rtx get_stored_val (store_info_t, enum machine_mode, HOST_WIDE_INT, |
| HOST_WIDE_INT, basic_block, bool); |
| |
| |
| /* 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, rhs, const_rhs, mem_addr; |
| HOST_WIDE_INT offset = 0; |
| HOST_WIDE_INT width = 0; |
| alias_set_type 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, redundant_reason; |
| bool store_is_unused; |
| |
| if (GET_CODE (body) != SET && GET_CODE (body) != CLOBBER) |
| return 0; |
| |
| mem = SET_DEST (body); |
| |
| /* 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, mem) != NULL); |
| |
| /* Check whether that value is a suitable memory location. */ |
| 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; |
| return 0; |
| } |
| /* Handle (set (mem:BLK (addr) [... S36 ...]) (const_int 0)) |
| as memset (addr, 0, 36); */ |
| else if (!MEM_SIZE (mem) |
| || !CONST_INT_P (MEM_SIZE (mem)) |
| || GET_CODE (body) != SET |
| || INTVAL (MEM_SIZE (mem)) <= 0 |
| || INTVAL (MEM_SIZE (mem)) > MAX_OFFSET |
| || !CONST_INT_P (SET_SRC (body))) |
| { |
| 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; |
| } |
| |
| if (GET_MODE (mem) == BLKmode) |
| width = INTVAL (MEM_SIZE (mem)); |
| else |
| { |
| width = GET_MODE_SIZE (GET_MODE (mem)); |
| gcc_assert ((unsigned) width <= HOST_BITS_PER_WIDE_INT); |
| } |
| |
| if (spill_alias_set) |
| { |
| bitmap store1 = clear_alias_group->store1_p; |
| bitmap store2 = clear_alias_group->store2_p; |
| |
| gcc_assert (GET_MODE (mem) != BLKmode); |
| |
| 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 = (store_info_t) 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 = (store_info_t) 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 |
| { |
| rtx base_term = find_base_term (XEXP (mem, 0)); |
| if (!base_term |
| || (GET_CODE (base_term) == ADDRESS |
| && GET_MODE (base_term) == Pmode |
| && XEXP (base_term, 0) == stack_pointer_rtx)) |
| insn_info->stack_pointer_based = true; |
| insn_info->contains_cselib_groups = true; |
| |
| store_info = (store_info_t) pool_alloc (cse_store_info_pool); |
| group_id = -1; |
| |
| if (dump_file) |
| fprintf (dump_file, " processing cselib store [%d..%d)\n", |
| (int)offset, (int)(offset+width)); |
| } |
| |
| const_rhs = rhs = NULL_RTX; |
| if (GET_CODE (body) == SET |
| /* No place to keep the value after ra. */ |
| && !reload_completed |
| && (REG_P (SET_SRC (body)) |
| || GET_CODE (SET_SRC (body)) == SUBREG |
| || CONSTANT_P (SET_SRC (body))) |
| && !MEM_VOLATILE_P (mem) |
| /* Sometimes the store and reload is used for truncation and |
| rounding. */ |
| && !(FLOAT_MODE_P (GET_MODE (mem)) && (flag_float_store))) |
| { |
| rhs = SET_SRC (body); |
| if (CONSTANT_P (rhs)) |
| const_rhs = rhs; |
| else if (body == PATTERN (insn_info->insn)) |
| { |
| rtx tem = find_reg_note (insn_info->insn, REG_EQUAL, NULL_RTX); |
| if (tem && CONSTANT_P (XEXP (tem, 0))) |
| const_rhs = XEXP (tem, 0); |
| } |
| if (const_rhs == NULL_RTX && REG_P (rhs)) |
| { |
| rtx tem = cselib_expand_value_rtx (rhs, scratch, 5); |
| |
| if (tem && CONSTANT_P (tem)) |
| const_rhs = tem; |
| } |
| } |
| |
| /* Check to see if this stores causes some other stores to be |
| dead. */ |
| ptr = active_local_stores; |
| last = NULL; |
| redundant_reason = NULL; |
| mem = canon_rtx (mem); |
| /* For alias_set != 0 canon_true_dependence should be never called. */ |
| if (spill_alias_set) |
| mem_addr = NULL_RTX; |
| else |
| { |
| if (group_id < 0) |
| mem_addr = base->val_rtx; |
| else |
| { |
| group_info_t group |
| = VEC_index (group_info_t, rtx_group_vec, group_id); |
| mem_addr = group->canon_base_addr; |
| } |
| if (offset) |
| mem_addr = plus_constant (mem_addr, offset); |
| } |
| |
| while (ptr) |
| { |
| insn_info_t next = ptr->next_local_store; |
| store_info_t s_info = ptr->store_rec; |
| bool del = true; |
| |
| /* Skip the clobbers. We delete the active insn if this insn |
| shadows 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) |
| del = 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)) |
| { |
| del = true; |
| set_all_positions_unneeded (s_info); |
| } |
| 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); |
| |
| /* Even if PTR won't be eliminated as unneeded, if both |
| PTR and this insn store the same constant value, we might |
| eliminate this insn instead. */ |
| if (s_info->const_rhs |
| && const_rhs |
| && offset >= s_info->begin |
| && offset + width <= s_info->end |
| && all_positions_needed_p (s_info, offset - s_info->begin, |
| width)) |
| { |
| if (GET_MODE (mem) == BLKmode) |
| { |
| if (GET_MODE (s_info->mem) == BLKmode |
| && s_info->const_rhs == const_rhs) |
| redundant_reason = ptr; |
| } |
| else if (s_info->const_rhs == const0_rtx |
| && const_rhs == const0_rtx) |
| redundant_reason = ptr; |
| else |
| { |
| rtx val; |
| start_sequence (); |
| val = get_stored_val (s_info, GET_MODE (mem), |
| offset, offset + width, |
| BLOCK_FOR_INSN (insn_info->insn), |
| true); |
| if (get_insns () != NULL) |
| val = NULL_RTX; |
| end_sequence (); |
| if (val && rtx_equal_p (val, const_rhs)) |
| redundant_reason = ptr; |
| } |
| } |
| |
| for (i = MAX (offset, s_info->begin); |
| i < offset + width && i < s_info->end; |
| i++) |
| set_position_unneeded (s_info, 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, mem_addr, rtx_varies_p)) |
| { |
| s_info->rhs = NULL; |
| s_info->const_rhs = NULL; |
| } |
| } |
| |
| /* An insn can be deleted if every position of every one of |
| its s_infos is zero. */ |
| if (any_positions_needed_p (s_info) |
| || ptr->cannot_delete) |
| del = false; |
| |
| if (del) |
| { |
| 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; |
| } |
| |
| /* Finish filling in the store_info. */ |
| store_info->next = insn_info->store_rec; |
| insn_info->store_rec = store_info; |
| store_info->mem = mem; |
| store_info->alias_set = spill_alias_set; |
| store_info->mem_addr = mem_addr; |
| store_info->cse_base = base; |
| if (width > HOST_BITS_PER_WIDE_INT) |
| { |
| store_info->is_large = true; |
| store_info->positions_needed.large.count = 0; |
| store_info->positions_needed.large.bitmap = BITMAP_ALLOC (NULL); |
| } |
| else |
| { |
| store_info->is_large = false; |
| store_info->positions_needed.small_bitmask = lowpart_bitmask (width); |
| } |
| store_info->group_id = group_id; |
| store_info->begin = offset; |
| store_info->end = offset + width; |
| store_info->is_set = GET_CODE (body) == SET; |
| store_info->rhs = rhs; |
| store_info->const_rhs = const_rhs; |
| store_info->redundant_reason = redundant_reason; |
| |
| /* 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"); |
| } |
| |
| |
| /* If the modes are different and the value's source and target do not |
| line up, we need to extract the value from lower part of the rhs of |
| the store, shift it, and then put it into a form that can be shoved |
| into the read_insn. This function generates a right SHIFT of a |
| value that is at least ACCESS_SIZE bytes wide of READ_MODE. The |
| shift sequence is returned or NULL if we failed to find a |
| shift. */ |
| |
| static rtx |
| find_shift_sequence (int access_size, |
| store_info_t store_info, |
| enum machine_mode read_mode, |
| int shift, bool speed, bool require_cst) |
| { |
| enum machine_mode store_mode = GET_MODE (store_info->mem); |
| enum machine_mode new_mode; |
| rtx read_reg = NULL; |
| |
| /* Some machines like the x86 have shift insns for each size of |
| operand. Other machines like the ppc or the ia-64 may only have |
| shift insns that shift values within 32 or 64 bit registers. |
| This loop tries to find the smallest shift insn that will right |
| justify the value we want to read but is available in one insn on |
| the machine. */ |
| |
| for (new_mode = smallest_mode_for_size (access_size * BITS_PER_UNIT, |
| MODE_INT); |
| GET_MODE_BITSIZE (new_mode) <= BITS_PER_WORD; |
| new_mode = GET_MODE_WIDER_MODE (new_mode)) |
| { |
| rtx target, new_reg, shift_seq, insn, new_lhs; |
| int cost; |
| |
| /* If a constant was stored into memory, try to simplify it here, |
| otherwise the cost of the shift might preclude this optimization |
| e.g. at -Os, even when no actual shift will be needed. */ |
| if (store_info->const_rhs) |
| { |
| unsigned int byte = subreg_lowpart_offset (new_mode, store_mode); |
| rtx ret = simplify_subreg (new_mode, store_info->const_rhs, |
| store_mode, byte); |
| if (ret && CONSTANT_P (ret)) |
| { |
| ret = simplify_const_binary_operation (LSHIFTRT, new_mode, |
| ret, GEN_INT (shift)); |
| if (ret && CONSTANT_P (ret)) |
| { |
| byte = subreg_lowpart_offset (read_mode, new_mode); |
| ret = simplify_subreg (read_mode, ret, new_mode, byte); |
| if (ret && CONSTANT_P (ret) |
| && rtx_cost (ret, SET, speed) <= COSTS_N_INSNS (1)) |
| return ret; |
| } |
| } |
| } |
| |
| if (require_cst) |
| return NULL_RTX; |
| |
| /* Try a wider mode if truncating the store mode to NEW_MODE |
| requires a real instruction. */ |
| if (GET_MODE_BITSIZE (new_mode) < GET_MODE_BITSIZE (store_mode) |
| && !TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (new_mode), |
| GET_MODE_BITSIZE (store_mode))) |
| continue; |
| |
| /* Also try a wider mode if the necessary punning is either not |
| desirable or not possible. */ |
| if (!CONSTANT_P (store_info->rhs) |
| && !MODES_TIEABLE_P (new_mode, store_mode)) |
| continue; |
| |
| new_reg = gen_reg_rtx (new_mode); |
| |
| start_sequence (); |
| |
| /* In theory we could also check for an ashr. Ian Taylor knows |
| of one dsp where the cost of these two was not the same. But |
| this really is a rare case anyway. */ |
| target = expand_binop (new_mode, lshr_optab, new_reg, |
| GEN_INT (shift), new_reg, 1, OPTAB_DIRECT); |
| |
| shift_seq = get_insns (); |
| end_sequence (); |
| |
| if (target != new_reg || shift_seq == NULL) |
| continue; |
| |
| cost = 0; |
| for (insn = shift_seq; insn != NULL_RTX; insn = NEXT_INSN (insn)) |
| if (INSN_P (insn)) |
| cost += insn_rtx_cost (PATTERN (insn), speed); |
| |
| /* The computation up to here is essentially independent |
| of the arguments and could be precomputed. It may |
| not be worth doing so. We could precompute if |
| worthwhile or at least cache the results. The result |
| technically depends on both SHIFT and ACCESS_SIZE, |
| but in practice the answer will depend only on ACCESS_SIZE. */ |
| |
| if (cost > COSTS_N_INSNS (1)) |
| continue; |
| |
| new_lhs = extract_low_bits (new_mode, store_mode, |
| copy_rtx (store_info->rhs)); |
| if (new_lhs == NULL_RTX) |
| continue; |
| |
| /* We found an acceptable shift. Generate a move to |
| take the value from the store and put it into the |
| shift pseudo, then shift it, then generate another |
| move to put in into the target of the read. */ |
| emit_move_insn (new_reg, new_lhs); |
| emit_insn (shift_seq); |
| read_reg = extract_low_bits (read_mode, new_mode, new_reg); |
| break; |
| } |
| |
| return read_reg; |
| } |
| |
| |
| /* Call back for note_stores to find the hard regs set or clobbered by |
| insn. Data is a bitmap of the hardregs set so far. */ |
| |
| static void |
| look_for_hardregs (rtx x, const_rtx pat ATTRIBUTE_UNUSED, void *data) |
| { |
| bitmap regs_set = (bitmap) data; |
| |
| if (REG_P (x) |
| && REGNO (x) < FIRST_PSEUDO_REGISTER) |
| { |
| int regno = REGNO (x); |
| int n = hard_regno_nregs[regno][GET_MODE (x)]; |
| while (--n >= 0) |
| bitmap_set_bit (regs_set, regno + n); |
| } |
| } |
| |
| /* Helper function for replace_read and record_store. |
| Attempt to return a value stored in STORE_INFO, from READ_BEGIN |
| to one before READ_END bytes read in READ_MODE. Return NULL |
| if not successful. If REQUIRE_CST is true, return always constant. */ |
| |
| static rtx |
| get_stored_val (store_info_t store_info, enum machine_mode read_mode, |
| HOST_WIDE_INT read_begin, HOST_WIDE_INT read_end, |
| basic_block bb, bool require_cst) |
| { |
| enum machine_mode store_mode = GET_MODE (store_info->mem); |
| int shift; |
| int access_size; /* In bytes. */ |
| rtx read_reg; |
| |
| /* To get here the read is within the boundaries of the write so |
| shift will never be negative. Start out with the shift being in |
| bytes. */ |
| if (store_mode == BLKmode) |
| shift = 0; |
| else if (BYTES_BIG_ENDIAN) |
| shift = store_info->end - read_end; |
| else |
| shift = read_begin - store_info->begin; |
| |
| access_size = shift + GET_MODE_SIZE (read_mode); |
| |
| /* From now on it is bits. */ |
| shift *= BITS_PER_UNIT; |
| |
| if (shift) |
| read_reg = find_shift_sequence (access_size, store_info, read_mode, shift, |
| optimize_bb_for_speed_p (bb), |
| require_cst); |
| else if (store_mode == BLKmode) |
| { |
| /* The store is a memset (addr, const_val, const_size). */ |
| gcc_assert (CONST_INT_P (store_info->rhs)); |
| store_mode = int_mode_for_mode (read_mode); |
| if (store_mode == BLKmode) |
| read_reg = NULL_RTX; |
| else if (store_info->rhs == const0_rtx) |
| read_reg = extract_low_bits (read_mode, store_mode, const0_rtx); |
| else if (GET_MODE_BITSIZE (store_mode) > HOST_BITS_PER_WIDE_INT |
| || BITS_PER_UNIT >= HOST_BITS_PER_WIDE_INT) |
| read_reg = NULL_RTX; |
| else |
| { |
| unsigned HOST_WIDE_INT c |
| = INTVAL (store_info->rhs) |
| & (((HOST_WIDE_INT) 1 << BITS_PER_UNIT) - 1); |
| int shift = BITS_PER_UNIT; |
| while (shift < HOST_BITS_PER_WIDE_INT) |
| { |
| c |= (c << shift); |
| shift <<= 1; |
| } |
| read_reg = GEN_INT (trunc_int_for_mode (c, store_mode)); |
| read_reg = extract_low_bits (read_mode, store_mode, read_reg); |
| } |
| } |
| else if (store_info->const_rhs |
| && (require_cst |
| || GET_MODE_CLASS (read_mode) != GET_MODE_CLASS (store_mode))) |
| read_reg = extract_low_bits (read_mode, store_mode, |
| copy_rtx (store_info->const_rhs)); |
| else |
| read_reg = extract_low_bits (read_mode, store_mode, |
| copy_rtx (store_info->rhs)); |
| if (require_cst && read_reg && !CONSTANT_P (read_reg)) |
| read_reg = NULL_RTX; |
| return read_reg; |
| } |
| |
| /* Take a sequence of: |
| A <- r1 |
| ... |
| ... <- A |
| |
| and change it into |
| r2 <- r1 |
| A <- r1 |
| ... |
| ... <- r2 |
| |
| or |
| |
| r3 <- extract (r1) |
| r3 <- r3 >> shift |
| r2 <- extract (r3) |
| ... <- r2 |
| |
| or |
| |
| r2 <- extract (r1) |
| ... <- r2 |
| |
| Depending on the alignment and the mode of the store and |
| subsequent load. |
| |
| |
| The STORE_INFO and STORE_INSN are for the store and 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, |
| bitmap regs_live) |
| { |
| enum machine_mode store_mode = GET_MODE (store_info->mem); |
| enum machine_mode read_mode = GET_MODE (read_info->mem); |
| rtx insns, this_insn, read_reg; |
| basic_block bb; |
| |
| if (!dbg_cnt (dse)) |
| return false; |
| |
| /* Create a sequence of instructions to set up the read register. |
| This sequence goes immediately before the store and its result |
| is read by the load. |
| |
| We need to keep this in perspective. We are replacing a read |
| with a sequence of insns, but the read will almost certainly be |
| in cache, so it is not going to be an expensive one. Thus, we |
| are not willing to do a multi insn shift or worse a subroutine |
| call to get rid of the read. */ |
| if (dump_file) |
| fprintf (dump_file, "trying to replace %smode load in insn %d" |
| " from %smode store in insn %d\n", |
| GET_MODE_NAME (read_mode), INSN_UID (read_insn->insn), |
| GET_MODE_NAME (store_mode), INSN_UID (store_insn->insn)); |
| start_sequence (); |
| bb = BLOCK_FOR_INSN (read_insn->insn); |
| read_reg = get_stored_val (store_info, |
| read_mode, read_info->begin, read_info->end, |
| bb, false); |
| if (read_reg == NULL_RTX) |
| { |
| end_sequence (); |
| if (dump_file) |
| fprintf (dump_file, " -- could not extract bits of stored value\n"); |
| return false; |
| } |
| /* Force the value into a new register so that it won't be clobbered |
| between the store and the load. */ |
| read_reg = copy_to_mode_reg (read_mode, read_reg); |
| insns = get_insns (); |
| end_sequence (); |
| |
| if (insns != NULL_RTX) |
| { |
| /* Now we have to scan the set of new instructions to see if the |
| sequence contains and sets of hardregs that happened to be |
| live at this point. For instance, this can happen if one of |
| the insns sets the CC and the CC happened to be live at that |
| point. This does occasionally happen, see PR 37922. */ |
| bitmap regs_set = BITMAP_ALLOC (NULL); |
| |
| for (this_insn = insns; this_insn != NULL_RTX; this_insn = NEXT_INSN (this_insn)) |
| note_stores (PATTERN (this_insn), look_for_hardregs, regs_set); |
| |
| bitmap_and_into (regs_set, regs_live); |
| if (!bitmap_empty_p (regs_set)) |
| { |
| if (dump_file) |
| { |
| fprintf (dump_file, |
| "abandoning replacement because sequence clobbers live hardregs:"); |
| df_print_regset (dump_file, regs_set); |
| } |
| |
| BITMAP_FREE (regs_set); |
| return false; |
| } |
| BITMAP_FREE (regs_set); |
| } |
| |
| if (validate_change (read_insn->insn, loc, read_reg, 0)) |
| { |
| deferred_change_t deferred_change = |
| (deferred_change_t) pool_alloc (deferred_change_pool); |
| |
| /* Insert this right before the store insn where it will be safe |
| from later insns that might change it before the read. */ |
| emit_insn_before (insns, store_insn->insn); |
| |
| /* And now for the kludge 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 ones 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". |
| |
| Problem (1) is fixable with a certain amount of engineering. |
| Problem (2) is requires starting the bb from scratch. This |
| could be expensive. |
| |
| So we are just going to have to lie. The move/extraction |
| insns are not really an issue, cselib did not see them. But |
| the use of the new pseudo read_insn is a real problem because |
| cselib has not scanned this insn. The way that we solve this |
| problem is that we are just going to put the mem back for now |
| and when we are finished with the block, we undo this. We |
| keep a table of mems to get rid of. At the end of the basic |
| block we can put them back. */ |
| |
| *loc = read_info->mem; |
| deferred_change->next = deferred_change_list; |
| deferred_change_list = deferred_change; |
| deferred_change->loc = loc; |
| deferred_change->reg = read_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); |
| if (dump_file) |
| { |
| fprintf (dump_file, " -- replaced the loaded MEM with "); |
| print_simple_rtl (dump_file, read_reg); |
| fprintf (dump_file, "\n"); |
| } |
| return true; |
| } |
| else |
| { |
| if (dump_file) |
| { |
| fprintf (dump_file, " -- replacing the loaded MEM with "); |
| print_simple_rtl (dump_file, read_reg); |
| fprintf (dump_file, " led to an invalid instruction\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, mem_addr; |
| bb_info_t bb_info; |
| insn_info_t insn_info; |
| HOST_WIDE_INT offset = 0; |
| HOST_WIDE_INT width = 0; |
| alias_set_type 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 = (read_info_t) 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; |
| /* For alias_set != 0 canon_true_dependence should be never called. */ |
| if (spill_alias_set) |
| mem_addr = NULL_RTX; |
| else |
| { |
| if (group_id < 0) |
| mem_addr = base->val_rtx; |
| else |
| { |
| group_info_t group |
| = VEC_index (group_info_t, rtx_group_vec, group_id); |
| mem_addr = group->canon_base_addr; |
| } |
| if (offset) |
| mem_addr = plus_constant (mem_addr, offset); |
| } |
| |
| /* We ignore the clobbers in store_info. The is mildly aggressive, |
| 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, mem_addr, 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, mem_addr, 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 |
| && all_positions_needed_p (store_info, |
| offset - store_info->begin, |
| width) |
| && replace_read (store_info, i_ptr, read_info, |
| insn_info, loc, bb_info->regs_live)) |
| 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 |
| && width != -1 |
| && offset >= store_info->begin |
| && offset + width <= store_info->end |
| && all_positions_needed_p (store_info, |
| offset - store_info->begin, width) |
| && replace_read (store_info, i_ptr, read_info, insn_info, loc, |
| bb_info->regs_live)) |
| return 0; |
| |
| if (!store_info->alias_set) |
| remove = canon_true_dependence (store_info->mem, |
| GET_MODE (store_info->mem), |
| store_info->mem_addr, |
| mem, mem_addr, 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); |
| } |
| |
| |
| /* Get arguments passed to CALL_INSN. Return TRUE if successful. |
| So far it only handles arguments passed in registers. */ |
| |
| static bool |
| get_call_args (rtx call_insn, tree fn, rtx *args, int nargs) |
| { |
| CUMULATIVE_ARGS args_so_far; |
| tree arg; |
| int idx; |
| |
| INIT_CUMULATIVE_ARGS (args_so_far, TREE_TYPE (fn), NULL_RTX, 0, 3); |
| |
| arg = TYPE_ARG_TYPES (TREE_TYPE (fn)); |
| for (idx = 0; |
| arg != void_list_node && idx < nargs; |
| arg = TREE_CHAIN (arg), idx++) |
| { |
| enum machine_mode mode = TYPE_MODE (TREE_VALUE (arg)); |
| rtx reg = FUNCTION_ARG (args_so_far, mode, NULL_TREE, 1), link, tmp; |
| if (!reg || !REG_P (reg) || GET_MODE (reg) != mode |
| || GET_MODE_CLASS (mode) != MODE_INT) |
| return false; |
| |
| for (link = CALL_INSN_FUNCTION_USAGE (call_insn); |
| link; |
| link = XEXP (link, 1)) |
| if (GET_CODE (XEXP (link, 0)) == USE) |
| { |
| args[idx] = XEXP (XEXP (link, 0), 0); |
| if (REG_P (args[idx]) |
| && REGNO (args[idx]) == REGNO (reg) |
| && (GET_MODE (args[idx]) == mode |
| || (GET_MODE_CLASS (GET_MODE (args[idx])) == MODE_INT |
| && (GET_MODE_SIZE (GET_MODE (args[idx])) |
| <= UNITS_PER_WORD) |
| && (GET_MODE_SIZE (GET_MODE (args[idx])) |
| > GET_MODE_SIZE (mode))))) |
| break; |
| } |
| if (!link) |
| return false; |
| |
| tmp = cselib_expand_value_rtx (args[idx], scratch, 5); |
| if (GET_MODE (args[idx]) != mode) |
| { |
| if (!tmp || !CONST_INT_P (tmp)) |
| return false; |
| tmp = GEN_INT (trunc_int_for_mode (INTVAL (tmp), mode)); |
| } |
| if (tmp) |
| args[idx] = tmp; |
| |
| FUNCTION_ARG_ADVANCE (args_so_far, mode, NULL_TREE, 1); |
| } |
| if (arg != void_list_node || idx != nargs) |
| return false; |
| return true; |
| } |
| |
| |
| /* 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 = (insn_info_t) 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 essentially |
| 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)) |
| { |
| bool const_call; |
| tree memset_call = NULL_TREE; |
| |
| 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. |
| memset and bzero don't read memory either. */ |
| const_call = RTL_CONST_CALL_P (insn); |
| if (!const_call) |
| { |
| rtx call = PATTERN (insn); |
| if (GET_CODE (call) == PARALLEL) |
| call = XVECEXP (call, 0, 0); |
| if (GET_CODE (call) == SET) |
| call = SET_SRC (call); |
| if (GET_CODE (call) == CALL |
| && MEM_P (XEXP (call, 0)) |
| && GET_CODE (XEXP (XEXP (call, 0), 0)) == SYMBOL_REF) |
| { |
| rtx symbol = XEXP (XEXP (call, 0), 0); |
| if (SYMBOL_REF_DECL (symbol) |
| && TREE_CODE (SYMBOL_REF_DECL (symbol)) == FUNCTION_DECL) |
| { |
| if ((DECL_BUILT_IN_CLASS (SYMBOL_REF_DECL (symbol)) |
| == BUILT_IN_NORMAL |
| && (DECL_FUNCTION_CODE (SYMBOL_REF_DECL (symbol)) |
| == BUILT_IN_MEMSET)) |
| || SYMBOL_REF_DECL (symbol) == block_clear_fn) |
| memset_call = SYMBOL_REF_DECL (symbol); |
| } |
| } |
| } |
| if (const_call || memset_call) |
| { |
| insn_info_t i_ptr = active_local_stores; |
| insn_info_t last = NULL; |
| |
| if (dump_file) |
| fprintf (dump_file, "%s call %d\n", |
| const_call ? "const" : "memset", INSN_UID (insn)); |
| |
| /* See the head comment of the frame_read field. */ |
| if (reload_completed) |
| insn_info->frame_read = true; |
| |
| /* Loop over the active stores and remove those which are |
| killed by the const function call. */ |
| while (i_ptr) |
| { |
| bool remove_store = false; |
| |
| /* The stack pointer based stores are always killed. */ |
| if (i_ptr->stack_pointer_based) |
| remove_store = true; |
| |
| /* If the frame is read, the frame related stores are killed. */ |
| else if (insn_info->frame_read) |
| { |
| 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->group_id >= 0 |
| && VEC_index (group_info_t, rtx_group_vec, |
| store_info->group_id)->frame_related) |
| remove_store = true; |
| } |
| |
| if (remove_store) |
| { |
| 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; |
| } |
| |
| if (memset_call) |
| { |
| rtx args[3]; |
| if (get_call_args (insn, memset_call, args, 3) |
| && CONST_INT_P (args[1]) |
| && CONST_INT_P (args[2]) |
| && INTVAL (args[2]) > 0) |
| { |
| rtx mem = gen_rtx_MEM (BLKmode, args[0]); |
| set_mem_size (mem, args[2]); |
| body = gen_rtx_SET (VOIDmode, mem, args[1]); |
| mems_found += record_store (body, bb_info); |
| if (dump_file) |
| fprintf (dump_file, "handling memset as BLKmode store\n"); |
| if (mems_found == 1) |
| { |
| insn_info->next_local_store = active_local_stores; |
| active_local_stores = insn_info; |
| } |
| } |
| } |
| } |
| |
| else |
| /* 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_refs_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, add it into the active_local_stores so |
| that it can be locally deleted if found dead or used for |
| replace_read and redundant constant store elimination. Otherwise mark |
| it as cannot delete. This simplifies the processing later. */ |
| if (mems_found == 1) |
| { |
| 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 del = 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)) |
| { |
| del = true; |
| break; |
| } |
| store_info = store_info->next; |
| } |
| |
| if (del) |
| { |
| 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; |
| bitmap regs_live = BITMAP_ALLOC (NULL); |
| |
| 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 = (bb_info_t) pool_alloc (bb_info_pool); |
| |
| memset (bb_info, 0, sizeof (struct bb_info)); |
| bitmap_set_bit (all_blocks, bb->index); |
| bb_info->regs_live = regs_live; |
| |
| bitmap_copy (regs_live, DF_LR_IN (bb)); |
| df_simulate_initialize_forwards (bb, regs_live); |
| |
| 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); |
| if (INSN_P (insn)) |
| df_simulate_one_insn_forwards (bb, insn, regs_live); |
| } |
| |
| /* 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 |
| overlapping 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 |
| && ! crtl->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 && !i_ptr->cannot_delete) |
| 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 && !i_ptr->cannot_delete) |
| 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) |
| { |
| store_info_t s_info = ptr->store_rec; |
| while (s_info && !s_info->is_set) |
| s_info = s_info->next; |
| if (s_info |
| && s_info->redundant_reason |
| && s_info->redundant_reason->insn |
| && !ptr->cannot_delete) |
| { |
| if (dump_file) |
| fprintf (dump_file, "Locally deleting insn %d " |
| "because insn %d stores the " |
| "same value and couldn't be " |
| "eliminated\n", |
| INSN_UID (ptr->insn), |
| INSN_UID (s_info->redundant_reason->insn)); |
| delete_dead_store_insn (ptr); |
| } |
| if (s_info) |
| s_info->redundant_reason = NULL; |
| free_store_info (ptr); |
| } |
| else |
| { |
| store_info_t s_info; |
| |
| /* Free at least positions_needed bitmaps. */ |
| for (s_info = ptr->store_rec; s_info; s_info = s_info->next) |
| if (s_info->is_large) |
| { |
| BITMAP_FREE (s_info->positions_needed.large.bitmap); |
| s_info->is_large = false; |
| } |
| } |
| ptr = ptr->prev_insn; |
| } |
| |
| free_alloc_pool (cse_store_info_pool); |
| } |
| bb_info->regs_live = NULL; |
| } |
| |
| BITMAP_FREE (regs_live); |
| 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 positions 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 (alias_set_type 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 = |
| (struct clear_alias_mode_holder *) 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 (alias_set_type 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; |
| |
| /* If this insn reads the frame, kill all the frame related stores. */ |
| if (insn_info->frame_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_addr, |
| read_info->mem, NULL_RTX, |
| 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 (
|