/mingw-w64-v2.0.999/gcc/src/gcc/df-core.c
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- /* Allocation for dataflow support routines.
- Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
- 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
- Originally contributed by Michael P. Hayes
- (m.hayes@elec.canterbury.ac.nz, mhayes@redhat.com)
- Major rewrite contributed by Danny Berlin (dberlin@dberlin.org)
- 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/>. */
- /*
- OVERVIEW:
- The files in this collection (df*.c,df.h) provide a general framework
- for solving dataflow problems. The global dataflow is performed using
- a good implementation of iterative dataflow analysis.
- The file df-problems.c provides problem instance for the most common
- dataflow problems: reaching defs, upward exposed uses, live variables,
- uninitialized variables, def-use chains, and use-def chains. However,
- the interface allows other dataflow problems to be defined as well.
- Dataflow analysis is available in most of the rtl backend (the parts
- between pass_df_initialize and pass_df_finish). It is quite likely
- that these boundaries will be expanded in the future. The only
- requirement is that there be a correct control flow graph.
- There are three variations of the live variable problem that are
- available whenever dataflow is available. The LR problem finds the
- areas that can reach a use of a variable, the UR problems finds the
- areas that can be reached from a definition of a variable. The LIVE
- problem finds the intersection of these two areas.
- There are several optional problems. These can be enabled when they
- are needed and disabled when they are not needed.
- Dataflow problems are generally solved in three layers. The bottom
- layer is called scanning where a data structure is built for each rtl
- insn that describes the set of defs and uses of that insn. Scanning
- is generally kept up to date, i.e. as the insns changes, the scanned
- version of that insn changes also. There are various mechanisms for
- making this happen and are described in the INCREMENTAL SCANNING
- section.
- In the middle layer, basic blocks are scanned to produce transfer
- functions which describe the effects of that block on the global
- dataflow solution. The transfer functions are only rebuilt if the
- some instruction within the block has changed.
- The top layer is the dataflow solution itself. The dataflow solution
- is computed by using an efficient iterative solver and the transfer
- functions. The dataflow solution must be recomputed whenever the
- control changes or if one of the transfer function changes.
- USAGE:
- Here is an example of using the dataflow routines.
- df_[chain,live,note,rd]_add_problem (flags);
- df_set_blocks (blocks);
- df_analyze ();
- df_dump (stderr);
- df_finish_pass (false);
- DF_[chain,live,note,rd]_ADD_PROBLEM adds a problem, defined by an
- instance to struct df_problem, to the set of problems solved in this
- instance of df. All calls to add a problem for a given instance of df
- must occur before the first call to DF_ANALYZE.
- Problems can be dependent on other problems. For instance, solving
- def-use or use-def chains is dependent on solving reaching
- definitions. As long as these dependencies are listed in the problem
- definition, the order of adding the problems is not material.
- Otherwise, the problems will be solved in the order of calls to
- df_add_problem. Note that it is not necessary to have a problem. In
- that case, df will just be used to do the scanning.
- DF_SET_BLOCKS is an optional call used to define a region of the
- function on which the analysis will be performed. The normal case is
- to analyze the entire function and no call to df_set_blocks is made.
- DF_SET_BLOCKS only effects the blocks that are effected when computing
- the transfer functions and final solution. The insn level information
- is always kept up to date.
- When a subset is given, the analysis behaves as if the function only
- contains those blocks and any edges that occur directly between the
- blocks in the set. Care should be taken to call df_set_blocks right
- before the call to analyze in order to eliminate the possibility that
- optimizations that reorder blocks invalidate the bitvector.
- DF_ANALYZE causes all of the defined problems to be (re)solved. When
- DF_ANALYZE is completes, the IN and OUT sets for each basic block
- contain the computer information. The DF_*_BB_INFO macros can be used
- to access these bitvectors. All deferred rescannings are down before
- the transfer functions are recomputed.
- DF_DUMP can then be called to dump the information produce to some
- file. This calls DF_DUMP_START, to print the information that is not
- basic block specific, and then calls DF_DUMP_TOP and DF_DUMP_BOTTOM
- for each block to print the basic specific information. These parts
- can all be called separately as part of a larger dump function.
- DF_FINISH_PASS causes df_remove_problem to be called on all of the
- optional problems. It also causes any insns whose scanning has been
- deferred to be rescanned as well as clears all of the changeable flags.
- Setting the pass manager TODO_df_finish flag causes this function to
- be run. However, the pass manager will call df_finish_pass AFTER the
- pass dumping has been done, so if you want to see the results of the
- optional problems in the pass dumps, use the TODO flag rather than
- calling the function yourself.
- INCREMENTAL SCANNING
- There are four ways of doing the incremental scanning:
- 1) Immediate rescanning - Calls to df_insn_rescan, df_notes_rescan,
- df_bb_delete, df_insn_change_bb have been added to most of
- the low level service functions that maintain the cfg and change
- rtl. Calling and of these routines many cause some number of insns
- to be rescanned.
- For most modern rtl passes, this is certainly the easiest way to
- manage rescanning the insns. This technique also has the advantage
- that the scanning information is always correct and can be relied
- upon even after changes have been made to the instructions. This
- technique is contra indicated in several cases:
- a) If def-use chains OR use-def chains (but not both) are built,
- using this is SIMPLY WRONG. The problem is that when a ref is
- deleted that is the target of an edge, there is not enough
- information to efficiently find the source of the edge and
- delete the edge. This leaves a dangling reference that may
- cause problems.
- b) If def-use chains AND use-def chains are built, this may
- produce unexpected results. The problem is that the incremental
- scanning of an insn does not know how to repair the chains that
- point into an insn when the insn changes. So the incremental
- scanning just deletes the chains that enter and exit the insn
- being changed. The dangling reference issue in (a) is not a
- problem here, but if the pass is depending on the chains being
- maintained after insns have been modified, this technique will
- not do the correct thing.
- c) If the pass modifies insns several times, this incremental
- updating may be expensive.
- d) If the pass modifies all of the insns, as does register
- allocation, it is simply better to rescan the entire function.
- 2) Deferred rescanning - Calls to df_insn_rescan, df_notes_rescan, and
- df_insn_delete do not immediately change the insn but instead make
- a note that the insn needs to be rescanned. The next call to
- df_analyze, df_finish_pass, or df_process_deferred_rescans will
- cause all of the pending rescans to be processed.
- This is the technique of choice if either 1a, 1b, or 1c are issues
- in the pass. In the case of 1a or 1b, a call to df_finish_pass
- (either manually or via TODO_df_finish) should be made before the
- next call to df_analyze or df_process_deferred_rescans.
- This mode is also used by a few passes that still rely on note_uses,
- note_stores and for_each_rtx instead of using the DF data. This
- can be said to fall under case 1c.
- To enable this mode, call df_set_flags (DF_DEFER_INSN_RESCAN).
- (This mode can be cleared by calling df_clear_flags
- (DF_DEFER_INSN_RESCAN) but this does not cause the deferred insns to
- be rescanned.
- 3) Total rescanning - In this mode the rescanning is disabled.
- Only when insns are deleted is the df information associated with
- it also deleted. At the end of the pass, a call must be made to
- df_insn_rescan_all. This method is used by the register allocator
- since it generally changes each insn multiple times (once for each ref)
- and does not need to make use of the updated scanning information.
- 4) Do it yourself - In this mechanism, the pass updates the insns
- itself using the low level df primitives. Currently no pass does
- this, but it has the advantage that it is quite efficient given
- that the pass generally has exact knowledge of what it is changing.
- DATA STRUCTURES
- Scanning produces a `struct df_ref' data structure (ref) is allocated
- for every register reference (def or use) and this records the insn
- and bb the ref is found within. The refs are linked together in
- chains of uses and defs for each insn and for each register. Each ref
- also has a chain field that links all the use refs for a def or all
- the def refs for a use. This is used to create use-def or def-use
- chains.
- Different optimizations have different needs. Ultimately, only
- register allocation and schedulers should be using the bitmaps
- produced for the live register and uninitialized register problems.
- The rest of the backend should be upgraded to using and maintaining
- the linked information such as def use or use def chains.
- PHILOSOPHY:
- While incremental bitmaps are not worthwhile to maintain, incremental
- chains may be perfectly reasonable. The fastest way to build chains
- from scratch or after significant modifications is to build reaching
- definitions (RD) and build the chains from this.
- However, general algorithms for maintaining use-def or def-use chains
- are not practical. The amount of work to recompute the chain any
- chain after an arbitrary change is large. However, with a modest
- amount of work it is generally possible to have the application that
- uses the chains keep them up to date. The high level knowledge of
- what is really happening is essential to crafting efficient
- incremental algorithms.
- As for the bit vector problems, there is no interface to give a set of
- blocks over with to resolve the iteration. In general, restarting a
- dataflow iteration is difficult and expensive. Again, the best way to
- keep the dataflow information up to data (if this is really what is
- needed) it to formulate a problem specific solution.
- There are fine grained calls for creating and deleting references from
- instructions in df-scan.c. However, these are not currently connected
- to the engine that resolves the dataflow equations.
- DATA STRUCTURES:
- The basic object is a DF_REF (reference) and this may either be a
- DEF (definition) or a USE of a register.
- These are linked into a variety of lists; namely reg-def, reg-use,
- insn-def, insn-use, def-use, and use-def lists. For example, the
- reg-def lists contain all the locations that define a given register
- while the insn-use lists contain all the locations that use a
- register.
- Note that the reg-def and reg-use chains are generally short for
- pseudos and long for the hard registers.
- ACCESSING INSNS:
- 1) The df insn information is kept in an array of DF_INSN_INFO objects.
- The array is indexed by insn uid, and every DF_REF points to the
- DF_INSN_INFO object of the insn that contains the reference.
- 2) Each insn has three sets of refs, which are linked into one of three
- lists: The insn's defs list (accessed by the DF_INSN_INFO_DEFS,
- DF_INSN_DEFS, or DF_INSN_UID_DEFS macros), the insn's uses list
- (accessed by the DF_INSN_INFO_USES, DF_INSN_USES, or
- DF_INSN_UID_USES macros) or the insn's eq_uses list (accessed by the
- DF_INSN_INFO_EQ_USES, DF_INSN_EQ_USES or DF_INSN_UID_EQ_USES macros).
- The latter list are the list of references in REG_EQUAL or REG_EQUIV
- notes. These macros produce a ref (or NULL), the rest of the list
- can be obtained by traversal of the NEXT_REF field (accessed by the
- DF_REF_NEXT_REF macro.) There is no significance to the ordering of
- the uses or refs in an instruction.
- 3) Each insn has a logical uid field (LUID) which is stored in the
- DF_INSN_INFO object for the insn. The LUID field is accessed by
- the DF_INSN_INFO_LUID, DF_INSN_LUID, and DF_INSN_UID_LUID macros.
- When properly set, the LUID is an integer that numbers each insn in
- the basic block, in order from the start of the block.
- The numbers are only correct after a call to df_analyze. They will
- rot after insns are added deleted or moved round.
- ACCESSING REFS:
- There are 4 ways to obtain access to refs:
- 1) References are divided into two categories, REAL and ARTIFICIAL.
- REAL refs are associated with instructions.
- ARTIFICIAL refs are associated with basic blocks. The heads of
- these lists can be accessed by calling df_get_artificial_defs or
- df_get_artificial_uses for the particular basic block.
- Artificial defs and uses occur both at the beginning and ends of blocks.
- For blocks that area at the destination of eh edges, the
- artificial uses and defs occur at the beginning. The defs relate
- to the registers specified in EH_RETURN_DATA_REGNO and the uses
- relate to the registers specified in ED_USES. Logically these
- defs and uses should really occur along the eh edge, but there is
- no convenient way to do this. Artificial edges that occur at the
- beginning of the block have the DF_REF_AT_TOP flag set.
- Artificial uses occur at the end of all blocks. These arise from
- the hard registers that are always live, such as the stack
- register and are put there to keep the code from forgetting about
- them.
- Artificial defs occur at the end of the entry block. These arise
- from registers that are live at entry to the function.
- 2) There are three types of refs: defs, uses and eq_uses. (Eq_uses are
- uses that appear inside a REG_EQUAL or REG_EQUIV note.)
- All of the eq_uses, uses and defs associated with each pseudo or
- hard register may be linked in a bidirectional chain. These are
- called reg-use or reg_def chains. If the changeable flag
- DF_EQ_NOTES is set when the chains are built, the eq_uses will be
- treated like uses. If it is not set they are ignored.
- The first use, eq_use or def for a register can be obtained using
- the DF_REG_USE_CHAIN, DF_REG_EQ_USE_CHAIN or DF_REG_DEF_CHAIN
- macros. Subsequent uses for the same regno can be obtained by
- following the next_reg field of the ref. The number of elements in
- each of the chains can be found by using the DF_REG_USE_COUNT,
- DF_REG_EQ_USE_COUNT or DF_REG_DEF_COUNT macros.
- In previous versions of this code, these chains were ordered. It
- has not been practical to continue this practice.
- 3) If def-use or use-def chains are built, these can be traversed to
- get to other refs. If the flag DF_EQ_NOTES has been set, the chains
- include the eq_uses. Otherwise these are ignored when building the
- chains.
- 4) An array of all of the uses (and an array of all of the defs) can
- be built. These arrays are indexed by the value in the id
- structure. These arrays are only lazily kept up to date, and that
- process can be expensive. To have these arrays built, call
- df_reorganize_defs or df_reorganize_uses. If the flag DF_EQ_NOTES
- has been set the array will contain the eq_uses. Otherwise these
- are ignored when building the array and assigning the ids. Note
- that the values in the id field of a ref may change across calls to
- df_analyze or df_reorganize_defs or df_reorganize_uses.
- If the only use of this array is to find all of the refs, it is
- better to traverse all of the registers and then traverse all of
- reg-use or reg-def chains.
- NOTES:
- Embedded addressing side-effects, such as POST_INC or PRE_INC, generate
- both a use and a def. These are both marked read/write to show that they
- are dependent. For example, (set (reg 40) (mem (post_inc (reg 42))))
- will generate a use of reg 42 followed by a def of reg 42 (both marked
- read/write). Similarly, (set (reg 40) (mem (pre_dec (reg 41))))
- generates a use of reg 41 then a def of reg 41 (both marked read/write),
- even though reg 41 is decremented before it is used for the memory
- address in this second example.
- A set to a REG inside a ZERO_EXTRACT, or a set to a non-paradoxical SUBREG
- for which the number of word_mode units covered by the outer mode is
- smaller than that covered by the inner mode, invokes a read-modify-write
- operation. We generate both a use and a def and again mark them
- read/write.
- Paradoxical subreg writes do not leave a trace of the old content, so they
- are write-only operations.
- */
- #include "config.h"
- #include "system.h"
- #include "coretypes.h"
- #include "tm.h"
- #include "rtl.h"
- #include "tm_p.h"
- #include "insn-config.h"
- #include "recog.h"
- #include "function.h"
- #include "regs.h"
- #include "alloc-pool.h"
- #include "flags.h"
- #include "hard-reg-set.h"
- #include "basic-block.h"
- #include "sbitmap.h"
- #include "bitmap.h"
- #include "df.h"
- #include "tree-pass.h"
- #include "params.h"
- static void *df_get_bb_info (struct dataflow *, unsigned int);
- static void df_set_bb_info (struct dataflow *, unsigned int, void *);
- static void df_clear_bb_info (struct dataflow *, unsigned int);
- #ifdef DF_DEBUG_CFG
- static void df_set_clean_cfg (void);
- #endif
- /* The obstack on which regsets are allocated. */
- struct bitmap_obstack reg_obstack;
- /* An obstack for bitmap not related to specific dataflow problems.
- This obstack should e.g. be used for bitmaps with a short life time
- such as temporary bitmaps. */
- bitmap_obstack df_bitmap_obstack;
- /*----------------------------------------------------------------------------
- Functions to create, destroy and manipulate an instance of df.
- ----------------------------------------------------------------------------*/
- struct df_d *df;
- /* Add PROBLEM (and any dependent problems) to the DF instance. */
- void
- df_add_problem (struct df_problem *problem)
- {
- struct dataflow *dflow;
- int i;
- /* First try to add the dependent problem. */
- if (problem->dependent_problem)
- df_add_problem (problem->dependent_problem);
- /* Check to see if this problem has already been defined. If it
- has, just return that instance, if not, add it to the end of the
- vector. */
- dflow = df->problems_by_index[problem->id];
- if (dflow)
- return;
- /* Make a new one and add it to the end. */
- dflow = XCNEW (struct dataflow);
- dflow->problem = problem;
- dflow->computed = false;
- dflow->solutions_dirty = true;
- df->problems_by_index[dflow->problem->id] = dflow;
- /* Keep the defined problems ordered by index. This solves the
- problem that RI will use the information from UREC if UREC has
- been defined, or from LIVE if LIVE is defined and otherwise LR.
- However for this to work, the computation of RI must be pushed
- after which ever of those problems is defined, but we do not
- require any of those except for LR to have actually been
- defined. */
- df->num_problems_defined++;
- for (i = df->num_problems_defined - 2; i >= 0; i--)
- {
- if (problem->id < df->problems_in_order[i]->problem->id)
- df->problems_in_order[i+1] = df->problems_in_order[i];
- else
- {
- df->problems_in_order[i+1] = dflow;
- return;
- }
- }
- df->problems_in_order[0] = dflow;
- }
- /* Set the MASK flags in the DFLOW problem. The old flags are
- returned. If a flag is not allowed to be changed this will fail if
- checking is enabled. */
- int
- df_set_flags (int changeable_flags)
- {
- int old_flags = df->changeable_flags;
- df->changeable_flags |= changeable_flags;
- return old_flags;
- }
- /* Clear the MASK flags in the DFLOW problem. The old flags are
- returned. If a flag is not allowed to be changed this will fail if
- checking is enabled. */
- int
- df_clear_flags (int changeable_flags)
- {
- int old_flags = df->changeable_flags;
- df->changeable_flags &= ~changeable_flags;
- return old_flags;
- }
- /* Set the blocks that are to be considered for analysis. If this is
- not called or is called with null, the entire function in
- analyzed. */
- void
- df_set_blocks (bitmap blocks)
- {
- if (blocks)
- {
- if (dump_file)
- bitmap_print (dump_file, blocks, "setting blocks to analyze ", "\n");
- if (df->blocks_to_analyze)
- {
- /* This block is called to change the focus from one subset
- to another. */
- int p;
- bitmap_head diff;
- bitmap_initialize (&diff, &df_bitmap_obstack);
- bitmap_and_compl (&diff, df->blocks_to_analyze, blocks);
- for (p = 0; p < df->num_problems_defined; p++)
- {
- struct dataflow *dflow = df->problems_in_order[p];
- if (dflow->optional_p && dflow->problem->reset_fun)
- dflow->problem->reset_fun (df->blocks_to_analyze);
- else if (dflow->problem->free_blocks_on_set_blocks)
- {
- bitmap_iterator bi;
- unsigned int bb_index;
- EXECUTE_IF_SET_IN_BITMAP (&diff, 0, bb_index, bi)
- {
- basic_block bb = BASIC_BLOCK (bb_index);
- if (bb)
- {
- void *bb_info = df_get_bb_info (dflow, bb_index);
- dflow->problem->free_bb_fun (bb, bb_info);
- df_clear_bb_info (dflow, bb_index);
- }
- }
- }
- }
- bitmap_clear (&diff);
- }
- else
- {
- /* This block of code is executed to change the focus from
- the entire function to a subset. */
- bitmap_head blocks_to_reset;
- bool initialized = false;
- int p;
- for (p = 0; p < df->num_problems_defined; p++)
- {
- struct dataflow *dflow = df->problems_in_order[p];
- if (dflow->optional_p && dflow->problem->reset_fun)
- {
- if (!initialized)
- {
- basic_block bb;
- bitmap_initialize (&blocks_to_reset, &df_bitmap_obstack);
- FOR_ALL_BB(bb)
- {
- bitmap_set_bit (&blocks_to_reset, bb->index);
- }
- }
- dflow->problem->reset_fun (&blocks_to_reset);
- }
- }
- if (initialized)
- bitmap_clear (&blocks_to_reset);
- df->blocks_to_analyze = BITMAP_ALLOC (&df_bitmap_obstack);
- }
- bitmap_copy (df->blocks_to_analyze, blocks);
- df->analyze_subset = true;
- }
- else
- {
- /* This block is executed to reset the focus to the entire
- function. */
- if (dump_file)
- fprintf (dump_file, "clearing blocks_to_analyze\n");
- if (df->blocks_to_analyze)
- {
- BITMAP_FREE (df->blocks_to_analyze);
- df->blocks_to_analyze = NULL;
- }
- df->analyze_subset = false;
- }
- /* Setting the blocks causes the refs to be unorganized since only
- the refs in the blocks are seen. */
- df_maybe_reorganize_def_refs (DF_REF_ORDER_NO_TABLE);
- df_maybe_reorganize_use_refs (DF_REF_ORDER_NO_TABLE);
- df_mark_solutions_dirty ();
- }
- /* Delete a DFLOW problem (and any problems that depend on this
- problem). */
- void
- df_remove_problem (struct dataflow *dflow)
- {
- struct df_problem *problem;
- int i;
- if (!dflow)
- return;
- problem = dflow->problem;
- gcc_assert (problem->remove_problem_fun);
- /* Delete any problems that depended on this problem first. */
- for (i = 0; i < df->num_problems_defined; i++)
- if (df->problems_in_order[i]->problem->dependent_problem == problem)
- df_remove_problem (df->problems_in_order[i]);
- /* Now remove this problem. */
- for (i = 0; i < df->num_problems_defined; i++)
- if (df->problems_in_order[i] == dflow)
- {
- int j;
- for (j = i + 1; j < df->num_problems_defined; j++)
- df->problems_in_order[j-1] = df->problems_in_order[j];
- df->problems_in_order[j-1] = NULL;
- df->num_problems_defined--;
- break;
- }
- (problem->remove_problem_fun) ();
- df->problems_by_index[problem->id] = NULL;
- }
- /* Remove all of the problems that are not permanent. Scanning, LR
- and (at -O2 or higher) LIVE are permanent, the rest are removable.
- Also clear all of the changeable_flags. */
- void
- df_finish_pass (bool verify ATTRIBUTE_UNUSED)
- {
- int i;
- int removed = 0;
- #ifdef ENABLE_DF_CHECKING
- int saved_flags;
- #endif
- if (!df)
- return;
- df_maybe_reorganize_def_refs (DF_REF_ORDER_NO_TABLE);
- df_maybe_reorganize_use_refs (DF_REF_ORDER_NO_TABLE);
- #ifdef ENABLE_DF_CHECKING
- saved_flags = df->changeable_flags;
- #endif
- for (i = 0; i < df->num_problems_defined; i++)
- {
- struct dataflow *dflow = df->problems_in_order[i];
- struct df_problem *problem = dflow->problem;
- if (dflow->optional_p)
- {
- gcc_assert (problem->remove_problem_fun);
- (problem->remove_problem_fun) ();
- df->problems_in_order[i] = NULL;
- df->problems_by_index[problem->id] = NULL;
- removed++;
- }
- }
- df->num_problems_defined -= removed;
- /* Clear all of the flags. */
- df->changeable_flags = 0;
- df_process_deferred_rescans ();
- /* Set the focus back to the whole function. */
- if (df->blocks_to_analyze)
- {
- BITMAP_FREE (df->blocks_to_analyze);
- df->blocks_to_analyze = NULL;
- df_mark_solutions_dirty ();
- df->analyze_subset = false;
- }
- #ifdef ENABLE_DF_CHECKING
- /* Verification will fail in DF_NO_INSN_RESCAN. */
- if (!(saved_flags & DF_NO_INSN_RESCAN))
- {
- df_lr_verify_transfer_functions ();
- if (df_live)
- df_live_verify_transfer_functions ();
- }
- #ifdef DF_DEBUG_CFG
- df_set_clean_cfg ();
- #endif
- #endif
- #ifdef ENABLE_CHECKING
- if (verify)
- df->changeable_flags |= DF_VERIFY_SCHEDULED;
- #endif
- }
- /* Set up the dataflow instance for the entire back end. */
- static unsigned int
- rest_of_handle_df_initialize (void)
- {
- gcc_assert (!df);
- df = XCNEW (struct df_d);
- df->changeable_flags = 0;
- bitmap_obstack_initialize (&df_bitmap_obstack);
- /* Set this to a conservative value. Stack_ptr_mod will compute it
- correctly later. */
- crtl->sp_is_unchanging = 0;
- df_scan_add_problem ();
- df_scan_alloc (NULL);
- /* These three problems are permanent. */
- df_lr_add_problem ();
- if (optimize > 1)
- df_live_add_problem ();
- df->postorder = XNEWVEC (int, last_basic_block);
- df->postorder_inverted = XNEWVEC (int, last_basic_block);
- df->n_blocks = post_order_compute (df->postorder, true, true);
- df->n_blocks_inverted = inverted_post_order_compute (df->postorder_inverted);
- gcc_assert (df->n_blocks == df->n_blocks_inverted);
- df->hard_regs_live_count = XNEWVEC (unsigned int, FIRST_PSEUDO_REGISTER);
- memset (df->hard_regs_live_count, 0,
- sizeof (unsigned int) * FIRST_PSEUDO_REGISTER);
- df_hard_reg_init ();
- /* After reload, some ports add certain bits to regs_ever_live so
- this cannot be reset. */
- df_compute_regs_ever_live (true);
- df_scan_blocks ();
- df_compute_regs_ever_live (false);
- return 0;
- }
- static bool
- gate_opt (void)
- {
- return optimize > 0;
- }
- struct rtl_opt_pass pass_df_initialize_opt =
- {
- {
- RTL_PASS,
- "dfinit", /* name */
- gate_opt, /* gate */
- rest_of_handle_df_initialize, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- TV_DF_SCAN, /* tv_id */
- 0, /* properties_required */
- 0, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- 0 /* todo_flags_finish */
- }
- };
- static bool
- gate_no_opt (void)
- {
- return optimize == 0;
- }
- struct rtl_opt_pass pass_df_initialize_no_opt =
- {
- {
- RTL_PASS,
- "no-opt dfinit", /* name */
- gate_no_opt, /* gate */
- rest_of_handle_df_initialize, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- TV_DF_SCAN, /* tv_id */
- 0, /* properties_required */
- 0, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- 0 /* todo_flags_finish */
- }
- };
- /* Free all the dataflow info and the DF structure. This should be
- called from the df_finish macro which also NULLs the parm. */
- static unsigned int
- rest_of_handle_df_finish (void)
- {
- int i;
- gcc_assert (df);
- for (i = 0; i < df->num_problems_defined; i++)
- {
- struct dataflow *dflow = df->problems_in_order[i];
- dflow->problem->free_fun ();
- }
- free (df->postorder);
- free (df->postorder_inverted);
- free (df->hard_regs_live_count);
- free (df);
- df = NULL;
- bitmap_obstack_release (&df_bitmap_obstack);
- return 0;
- }
- struct rtl_opt_pass pass_df_finish =
- {
- {
- RTL_PASS,
- "dfinish", /* name */
- NULL, /* gate */
- rest_of_handle_df_finish, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- TV_NONE, /* tv_id */
- 0, /* properties_required */
- 0, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- 0 /* todo_flags_finish */
- }
- };
- /*----------------------------------------------------------------------------
- The general data flow analysis engine.
- ----------------------------------------------------------------------------*/
- /* Return time BB when it was visited for last time. */
- #define BB_LAST_CHANGE_AGE(bb) ((ptrdiff_t)(bb)->aux)
- /* Helper function for df_worklist_dataflow.
- Propagate the dataflow forward.
- Given a BB_INDEX, do the dataflow propagation
- and set bits on for successors in PENDING
- if the out set of the dataflow has changed.
- AGE specify time when BB was visited last time.
- AGE of 0 means we are visiting for first time and need to
- compute transfer function to initialize datastructures.
- Otherwise we re-do transfer function only if something change
- while computing confluence functions.
- We need to compute confluence only of basic block that are younger
- then last visit of the BB.
- Return true if BB info has changed. This is always the case
- in the first visit. */
- static bool
- df_worklist_propagate_forward (struct dataflow *dataflow,
- unsigned bb_index,
- unsigned *bbindex_to_postorder,
- bitmap pending,
- sbitmap considered,
- ptrdiff_t age)
- {
- edge e;
- edge_iterator ei;
- basic_block bb = BASIC_BLOCK (bb_index);
- bool changed = !age;
- /* Calculate <conf_op> of incoming edges. */
- if (EDGE_COUNT (bb->preds) > 0)
- FOR_EACH_EDGE (e, ei, bb->preds)
- {
- if (age <= BB_LAST_CHANGE_AGE (e->src)
- && TEST_BIT (considered, e->src->index))
- changed |= dataflow->problem->con_fun_n (e);
- }
- else if (dataflow->problem->con_fun_0)
- dataflow->problem->con_fun_0 (bb);
- if (changed
- && dataflow->problem->trans_fun (bb_index))
- {
- /* The out set of this block has changed.
- Propagate to the outgoing blocks. */
- FOR_EACH_EDGE (e, ei, bb->succs)
- {
- unsigned ob_index = e->dest->index;
- if (TEST_BIT (considered, ob_index))
- bitmap_set_bit (pending, bbindex_to_postorder[ob_index]);
- }
- return true;
- }
- return false;
- }
- /* Helper function for df_worklist_dataflow.
- Propagate the dataflow backward. */
- static bool
- df_worklist_propagate_backward (struct dataflow *dataflow,
- unsigned bb_index,
- unsigned *bbindex_to_postorder,
- bitmap pending,
- sbitmap considered,
- ptrdiff_t age)
- {
- edge e;
- edge_iterator ei;
- basic_block bb = BASIC_BLOCK (bb_index);
- bool changed = !age;
- /* Calculate <conf_op> of incoming edges. */
- if (EDGE_COUNT (bb->succs) > 0)
- FOR_EACH_EDGE (e, ei, bb->succs)
- {
- if (age <= BB_LAST_CHANGE_AGE (e->dest)
- && TEST_BIT (considered, e->dest->index))
- changed |= dataflow->problem->con_fun_n (e);
- }
- else if (dataflow->problem->con_fun_0)
- dataflow->problem->con_fun_0 (bb);
- if (changed
- && dataflow->problem->trans_fun (bb_index))
- {
- /* The out set of this block has changed.
- Propagate to the outgoing blocks. */
- FOR_EACH_EDGE (e, ei, bb->preds)
- {
- unsigned ob_index = e->src->index;
- if (TEST_BIT (considered, ob_index))
- bitmap_set_bit (pending, bbindex_to_postorder[ob_index]);
- }
- return true;
- }
- return false;
- }
- /* Main dataflow solver loop.
- DATAFLOW is problem we are solving, PENDING is worklist of basic blocks we
- need to visit.
- BLOCK_IN_POSTORDER is array of size N_BLOCKS specifying postorder in BBs and
- BBINDEX_TO_POSTORDER is array mapping back BB->index to postorder possition.
- PENDING will be freed.
- The worklists are bitmaps indexed by postorder positions.
- The function implements standard algorithm for dataflow solving with two
- worklists (we are processing WORKLIST and storing new BBs to visit in
- PENDING).
- As an optimization we maintain ages when BB was changed (stored in bb->aux)
- and when it was last visited (stored in last_visit_age). This avoids need
- to re-do confluence function for edges to basic blocks whose source
- did not change since destination was visited last time. */
- static void
- df_worklist_dataflow_doublequeue (struct dataflow *dataflow,
- bitmap pending,
- sbitmap considered,
- int *blocks_in_postorder,
- unsigned *bbindex_to_postorder,
- int n_blocks)
- {
- enum df_flow_dir dir = dataflow->problem->dir;
- int dcount = 0;
- bitmap worklist = BITMAP_ALLOC (&df_bitmap_obstack);
- int age = 0;
- bool changed;
- VEC(int, heap) *last_visit_age = NULL;
- int prev_age;
- basic_block bb;
- int i;
- VEC_safe_grow_cleared (int, heap, last_visit_age, n_blocks);
- /* Double-queueing. Worklist is for the current iteration,
- and pending is for the next. */
- while (!bitmap_empty_p (pending))
- {
- bitmap_iterator bi;
- unsigned int index;
- /* Swap pending and worklist. */
- bitmap temp = worklist;
- worklist = pending;
- pending = temp;
- EXECUTE_IF_SET_IN_BITMAP (worklist, 0, index, bi)
- {
- unsigned bb_index;
- dcount++;
- bitmap_clear_bit (pending, index);
- bb_index = blocks_in_postorder[index];
- bb = BASIC_BLOCK (bb_index);
- prev_age = VEC_index (int, last_visit_age, index);
- if (dir == DF_FORWARD)
- changed = df_worklist_propagate_forward (dataflow, bb_index,
- bbindex_to_postorder,
- pending, considered,
- prev_age);
- else
- changed = df_worklist_propagate_backward (dataflow, bb_index,
- bbindex_to_postorder,
- pending, considered,
- prev_age);
- VEC_replace (int, last_visit_age, index, ++age);
- if (changed)
- bb->aux = (void *)(ptrdiff_t)age;
- }
- bitmap_clear (worklist);
- }
- for (i = 0; i < n_blocks; i++)
- BASIC_BLOCK (blocks_in_postorder[i])->aux = NULL;
- BITMAP_FREE (worklist);
- BITMAP_FREE (pending);
- VEC_free (int, heap, last_visit_age);
- /* Dump statistics. */
- if (dump_file)
- fprintf (dump_file, "df_worklist_dataflow_doublequeue:"
- "n_basic_blocks %d n_edges %d"
- " count %d (%5.2g)\n",
- n_basic_blocks, n_edges,
- dcount, dcount / (float)n_basic_blocks);
- }
- /* Worklist-based dataflow solver. It uses sbitmap as a worklist,
- with "n"-th bit representing the n-th block in the reverse-postorder order.
- The solver is a double-queue algorithm similar to the "double stack" solver
- from Cooper, Harvey and Kennedy, "Iterative data-flow analysis, Revisited".
- The only significant difference is that the worklist in this implementation
- is always sorted in RPO of the CFG visiting direction. */
- void
- df_worklist_dataflow (struct dataflow *dataflow,
- bitmap blocks_to_consider,
- int *blocks_in_postorder,
- int n_blocks)
- {
- bitmap pending = BITMAP_ALLOC (&df_bitmap_obstack);
- sbitmap considered = sbitmap_alloc (last_basic_block);
- bitmap_iterator bi;
- unsigned int *bbindex_to_postorder;
- int i;
- unsigned int index;
- enum df_flow_dir dir = dataflow->problem->dir;
- gcc_assert (dir != DF_NONE);
- /* BBINDEX_TO_POSTORDER maps the bb->index to the reverse postorder. */
- bbindex_to_postorder =
- (unsigned int *)xmalloc (last_basic_block * sizeof (unsigned int));
- /* Initialize the array to an out-of-bound value. */
- for (i = 0; i < last_basic_block; i++)
- bbindex_to_postorder[i] = last_basic_block;
- /* Initialize the considered map. */
- sbitmap_zero (considered);
- EXECUTE_IF_SET_IN_BITMAP (blocks_to_consider, 0, index, bi)
- {
- SET_BIT (considered, index);
- }
- /* Initialize the mapping of block index to postorder. */
- for (i = 0; i < n_blocks; i++)
- {
- bbindex_to_postorder[blocks_in_postorder[i]] = i;
- /* Add all blocks to the worklist. */
- bitmap_set_bit (pending, i);
- }
- /* Initialize the problem. */
- if (dataflow->problem->init_fun)
- dataflow->problem->init_fun (blocks_to_consider);
- /* Solve it. */
- df_worklist_dataflow_doublequeue (dataflow, pending, considered,
- blocks_in_postorder,
- bbindex_to_postorder,
- n_blocks);
- sbitmap_free (considered);
- free (bbindex_to_postorder);
- }
- /* Remove the entries not in BLOCKS from the LIST of length LEN, preserving
- the order of the remaining entries. Returns the length of the resulting
- list. */
- static unsigned
- df_prune_to_subcfg (int list[], unsigned len, bitmap blocks)
- {
- unsigned act, last;
- for (act = 0, last = 0; act < len; act++)
- if (bitmap_bit_p (blocks, list[act]))
- list[last++] = list[act];
- return last;
- }
- /* Execute dataflow analysis on a single dataflow problem.
- BLOCKS_TO_CONSIDER are the blocks whose solution can either be
- examined or will be computed. For calls from DF_ANALYZE, this is
- the set of blocks that has been passed to DF_SET_BLOCKS.
- */
- void
- df_analyze_problem (struct dataflow *dflow,
- bitmap blocks_to_consider,
- int *postorder, int n_blocks)
- {
- timevar_push (dflow->problem->tv_id);
- /* (Re)Allocate the datastructures necessary to solve the problem. */
- if (dflow->problem->alloc_fun)
- dflow->problem->alloc_fun (blocks_to_consider);
- #ifdef ENABLE_DF_CHECKING
- if (dflow->problem->verify_start_fun)
- dflow->problem->verify_start_fun ();
- #endif
- /* Set up the problem and compute the local information. */
- if (dflow->problem->local_compute_fun)
- dflow->problem->local_compute_fun (blocks_to_consider);
- /* Solve the equations. */
- if (dflow->problem->dataflow_fun)
- dflow->problem->dataflow_fun (dflow, blocks_to_consider,
- postorder, n_blocks);
- /* Massage the solution. */
- if (dflow->problem->finalize_fun)
- dflow->problem->finalize_fun (blocks_to_consider);
- #ifdef ENABLE_DF_CHECKING
- if (dflow->problem->verify_end_fun)
- dflow->problem->verify_end_fun ();
- #endif
- timevar_pop (dflow->problem->tv_id);
- dflow->computed = true;
- }
- /* Analyze dataflow info for the basic blocks specified by the bitmap
- BLOCKS, or for the whole CFG if BLOCKS is zero. */
- void
- df_analyze (void)
- {
- bitmap current_all_blocks = BITMAP_ALLOC (&df_bitmap_obstack);
- bool everything;
- int i;
- free (df->postorder);
- free (df->postorder_inverted);
- df->postorder = XNEWVEC (int, last_basic_block);
- df->postorder_inverted = XNEWVEC (int, last_basic_block);
- df->n_blocks = post_order_compute (df->postorder, true, true);
- df->n_blocks_inverted = inverted_post_order_compute (df->postorder_inverted);
- /* These should be the same. */
- gcc_assert (df->n_blocks == df->n_blocks_inverted);
- /* We need to do this before the df_verify_all because this is
- not kept incrementally up to date. */
- df_compute_regs_ever_live (false);
- df_process_deferred_rescans ();
- if (dump_file)
- fprintf (dump_file, "df_analyze called\n");
- #ifndef ENABLE_DF_CHECKING
- if (df->changeable_flags & DF_VERIFY_SCHEDULED)
- #endif
- df_verify ();
- for (i = 0; i < df->n_blocks; i++)
- bitmap_set_bit (current_all_blocks, df->postorder[i]);
- #ifdef ENABLE_CHECKING
- /* Verify that POSTORDER_INVERTED only contains blocks reachable from
- the ENTRY block. */
- for (i = 0; i < df->n_blocks_inverted; i++)
- gcc_assert (bitmap_bit_p (current_all_blocks, df->postorder_inverted[i]));
- #endif
- /* Make sure that we have pruned any unreachable blocks from these
- sets. */
- if (df->analyze_subset)
- {
- everything = false;
- bitmap_and_into (df->blocks_to_analyze, current_all_blocks);
- df->n_blocks = df_prune_to_subcfg (df->postorder,
- df->n_blocks, df->blocks_to_analyze);
- df->n_blocks_inverted = df_prune_to_subcfg (df->postorder_inverted,
- df->n_blocks_inverted,
- df->blocks_to_analyze);
- BITMAP_FREE (current_all_blocks);
- }
- else
- {
- everything = true;
- df->blocks_to_analyze = current_all_blocks;
- current_all_blocks = NULL;
- }
- /* Skip over the DF_SCAN problem. */
- for (i = 1; i < df->num_problems_defined; i++)
- {
- struct dataflow *dflow = df->problems_in_order[i];
- if (dflow->solutions_dirty)
- {
- if (dflow->problem->dir == DF_FORWARD)
- df_analyze_problem (dflow,
- df->blocks_to_analyze,
- df->postorder_inverted,
- df->n_blocks_inverted);
- else
- df_analyze_problem (dflow,
- df->blocks_to_analyze,
- df->postorder,
- df->n_blocks);
- }
- }
- if (everything)
- {
- BITMAP_FREE (df->blocks_to_analyze);
- df->blocks_to_analyze = NULL;
- }
- #ifdef DF_DEBUG_CFG
- df_set_clean_cfg ();
- #endif
- }
- /* Return the number of basic blocks from the last call to df_analyze. */
- int
- df_get_n_blocks (enum df_flow_dir dir)
- {
- gcc_assert (dir != DF_NONE);
- if (dir == DF_FORWARD)
- {
- gcc_assert (df->postorder_inverted);
- return df->n_blocks_inverted;
- }
- gcc_assert (df->postorder);
- return df->n_blocks;
- }
- /* Return a pointer to the array of basic blocks in the reverse postorder.
- Depending on the direction of the dataflow problem,
- it returns either the usual reverse postorder array
- or the reverse postorder of inverted traversal. */
- int *
- df_get_postorder (enum df_flow_dir dir)
- {
- gcc_assert (dir != DF_NONE);
- if (dir == DF_FORWARD)
- {
- gcc_assert (df->postorder_inverted);
- return df->postorder_inverted;
- }
- gcc_assert (df->postorder);
- return df->postorder;
- }
- static struct df_problem user_problem;
- static struct dataflow user_dflow;
- /* Interface for calling iterative dataflow with user defined
- confluence and transfer functions. All that is necessary is to
- supply DIR, a direction, CONF_FUN_0, a confluence function for
- blocks with no logical preds (or NULL), CONF_FUN_N, the normal
- confluence function, TRANS_FUN, the basic block transfer function,
- and BLOCKS, the set of blocks to examine, POSTORDER the blocks in
- postorder, and N_BLOCKS, the number of blocks in POSTORDER. */
- void
- df_simple_dataflow (enum df_flow_dir dir,
- df_init_function init_fun,
- df_confluence_function_0 con_fun_0,
- df_confluence_function_n con_fun_n,
- df_transfer_function trans_fun,
- bitmap blocks, int * postorder, int n_blocks)
- {
- memset (&user_problem, 0, sizeof (struct df_problem));
- user_problem.dir = dir;
- user_problem.init_fun = init_fun;
- user_problem.con_fun_0 = con_fun_0;
- user_problem.con_fun_n = con_fun_n;
- user_problem.trans_fun = trans_fun;
- user_dflow.problem = &user_problem;
- df_worklist_dataflow (&user_dflow, blocks, postorder, n_blocks);
- }
- /*----------------------------------------------------------------------------
- Functions to support limited incremental change.
- ----------------------------------------------------------------------------*/
- /* Get basic block info. */
- static void *
- df_get_bb_info (struct dataflow *dflow, unsigned int index)
- {
- if (dflow->block_info == NULL)
- return NULL;
- if (index >= dflow->block_info_size)
- return NULL;
- return (void *)((char *)dflow->block_info
- + index * dflow->problem->block_info_elt_size);
- }
- /* Set basic block info. */
- static void
- df_set_bb_info (struct dataflow *dflow, unsigned int index,
- void *bb_info)
- {
- gcc_assert (dflow->block_info);
- memcpy ((char *)dflow->block_info
- + index * dflow->problem->block_info_elt_size,
- bb_info, dflow->problem->block_info_elt_size);
- }
- /* Clear basic block info. */
- static void
- df_clear_bb_info (struct dataflow *dflow, unsigned int index)
- {
- gcc_assert (dflow->block_info);
- gcc_assert (dflow->block_info_size > index);
- memset ((char *)dflow->block_info
- + index * dflow->problem->block_info_elt_size,
- 0, dflow->problem->block_info_elt_size);
- }
- /* Mark the solutions as being out of date. */
- void
- df_mark_solutions_dirty (void)
- {
- if (df)
- {
- int p;
- for (p = 1; p < df->num_problems_defined; p++)
- df->problems_in_order[p]->solutions_dirty = true;
- }
- }
- /* Return true if BB needs it's transfer functions recomputed. */
- bool
- df_get_bb_dirty (basic_block bb)
- {
- return bitmap_bit_p ((df_live
- ? df_live : df_lr)->out_of_date_transfer_functions,
- bb->index);
- }
- /* Mark BB as needing it's transfer functions as being out of
- date. */
- void
- df_set_bb_dirty (basic_block bb)
- {
- bb->flags |= BB_MODIFIED;
- if (df)
- {
- int p;
- for (p = 1; p < df->num_problems_defined; p++)
- {
- struct dataflow *dflow = df->problems_in_order[p];
- if (dflow->out_of_date_transfer_functions)
- bitmap_set_bit (dflow->out_of_date_transfer_functions, bb->index);
- }
- df_mark_solutions_dirty ();
- }
- }
- /* Grow the bb_info array. */
- void
- df_grow_bb_info (struct dataflow *dflow)
- {
- unsigned int new_size = last_basic_block + 1;
- if (dflow->block_info_size < new_size)
- {
- new_size += new_size / 4;
- dflow->block_info
- = (void *)XRESIZEVEC (char, (char *)dflow->block_info,
- new_size
- * dflow->problem->block_info_elt_size);
- memset ((char *)dflow->block_info
- + dflow->block_info_size
- * dflow->problem->block_info_elt_size,
- 0,
- (new_size - dflow->block_info_size)
- * dflow->problem->block_info_elt_size);
- dflow->block_info_size = new_size;
- }
- }
- /* Clear the dirty bits. This is called from places that delete
- blocks. */
- static void
- df_clear_bb_dirty (basic_block bb)
- {
- int p;
- for (p = 1; p < df->num_problems_defined; p++)
- {
- struct dataflow *dflow = df->problems_in_order[p];
- if (dflow->out_of_date_transfer_functions)
- bitmap_clear_bit (dflow->out_of_date_transfer_functions, bb->index);
- }
- }
- /* Called from the rtl_compact_blocks to reorganize the problems basic
- block info. */
- void
- df_compact_blocks (void)
- {
- int i, p;
- basic_block bb;
- void *problem_temps;
- bitmap_head tmp;
- bitmap_initialize (&tmp, &df_bitmap_obstack);
- for (p = 0; p < df->num_problems_defined; p++)
- {
- struct dataflow *dflow = df->problems_in_order[p];
- /* Need to reorganize the out_of_date_transfer_functions for the
- dflow problem. */
- if (dflow->out_of_date_transfer_functions)
- {
- bitmap_copy (&tmp, dflow->out_of_date_transfer_functions);
- bitmap_clear (dflow->out_of_date_transfer_functions);
- if (bitmap_bit_p (&tmp, ENTRY_BLOCK))
- bitmap_set_bit (dflow->out_of_date_transfer_functions, ENTRY_BLOCK);
- if (bitmap_bit_p (&tmp, EXIT_BLOCK))
- bitmap_set_bit (dflow->out_of_date_transfer_functions, EXIT_BLOCK);
- i = NUM_FIXED_BLOCKS;
- FOR_EACH_BB (bb)
- {
- if (bitmap_bit_p (&tmp, bb->index))
- bitmap_set_bit (dflow->out_of_date_transfer_functions, i);
- i++;
- }
- }
- /* Now shuffle the block info for the problem. */
- if (dflow->problem->free_bb_fun)
- {
- int size = last_basic_block * dflow->problem->block_info_elt_size;
- problem_temps = XNEWVAR (char, size);
- df_grow_bb_info (dflow);
- memcpy (problem_temps, dflow->block_info, size);
- /* Copy the bb info from the problem tmps to the proper
- place in the block_info vector. Null out the copied
- item. The entry and exit blocks never move. */
- i = NUM_FIXED_BLOCKS;
- FOR_EACH_BB (bb)
- {
- df_set_bb_info (dflow, i,
- (char *)problem_temps
- + bb->index …
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