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/* Common subexpression elimination for GNU compiler.
Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998
1999, 2000, 2001, 2002, 2004 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING. If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA. */
#include "config.h"
/* stdio.h must precede rtl.h for FFS. */
#include "system.h"
#include "rtl.h"
#include "tm_p.h"
#include "regs.h"
#include "hard-reg-set.h"
#include "basic-block.h"
#include "flags.h"
#include "real.h"
#include "insn-config.h"
#include "recog.h"
#include "function.h"
#include "expr.h"
#include "toplev.h"
#include "output.h"
#include "ggc.h"
#include "timevar.h"
#include "target.h"
/* The basic idea of common subexpression elimination is to go
through the code, keeping a record of expressions that would
have the same value at the current scan point, and replacing
expressions encountered with the cheapest equivalent expression.
It is too complicated to keep track of the different possibilities
when control paths merge in this code; so, at each label, we forget all
that is known and start fresh. This can be described as processing each
extended basic block separately. We have a separate pass to perform
global CSE.
Note CSE can turn a conditional or computed jump into a nop or
an unconditional jump. When this occurs we arrange to run the jump
optimizer after CSE to delete the unreachable code.
We use two data structures to record the equivalent expressions:
a hash table for most expressions, and a vector of "quantity
numbers" to record equivalent (pseudo) registers.
The use of the special data structure for registers is desirable
because it is faster. It is possible because registers references
contain a fairly small number, the register number, taken from
a contiguously allocated series, and two register references are
identical if they have the same number. General expressions
do not have any such thing, so the only way to retrieve the
information recorded on an expression other than a register
is to keep it in a hash table.
Registers and "quantity numbers":
At the start of each basic block, all of the (hardware and pseudo)
registers used in the function are given distinct quantity
numbers to indicate their contents. During scan, when the code
copies one register into another, we copy the quantity number.
When a register is loaded in any other way, we allocate a new
quantity number to describe the value generated by this operation.
`reg_qty' records what quantity a register is currently thought
of as containing.
All real quantity numbers are greater than or equal to `max_reg'.
If register N has not been assigned a quantity, reg_qty[N] will equal N.
Quantity numbers below `max_reg' do not exist and none of the `qty_table'
entries should be referenced with an index below `max_reg'.
We also maintain a bidirectional chain of registers for each
quantity number. The `qty_table` members `first_reg' and `last_reg',
and `reg_eqv_table' members `next' and `prev' hold these chains.
The first register in a chain is the one whose lifespan is least local.
Among equals, it is the one that was seen first.
We replace any equivalent register with that one.
If two registers have the same quantity number, it must be true that
REG expressions with qty_table `mode' must be in the hash table for both
registers and must be in the same class.
The converse is not true. Since hard registers may be referenced in
any mode, two REG expressions might be equivalent in the hash table
but not have the same quantity number if the quantity number of one
of the registers is not the same mode as those expressions.
Constants and quantity numbers
When a quantity has a known constant value, that value is stored
in the appropriate qty_table `const_rtx'. This is in addition to
putting the constant in the hash table as is usual for non-regs.
Whether a reg or a constant is preferred is determined by the configuration
macro CONST_COSTS and will often depend on the constant value. In any
event, expressions containing constants can be simplified, by fold_rtx.
When a quantity has a known nearly constant value (such as an address
of a stack slot), that value is stored in the appropriate qty_table
`const_rtx'.
Integer constants don't have a machine mode. However, cse
determines the intended machine mode from the destination
of the instruction that moves the constant. The machine mode
is recorded in the hash table along with the actual RTL
constant expression so that different modes are kept separate.
Other expressions:
To record known equivalences among expressions in general
we use a hash table called `table'. It has a fixed number of buckets
that contain chains of `struct table_elt' elements for expressions.
These chains connect the elements whose expressions have the same
hash codes.
Other chains through the same elements connect the elements which
currently have equivalent values.
Register references in an expression are canonicalized before hashing
the expression. This is done using `reg_qty' and qty_table `first_reg'.
The hash code of a register reference is computed using the quantity
number, not the register number.
When the value of an expression changes, it is necessary to remove from the
hash table not just that expression but all expressions whose values
could be different as a result.
1. If the value changing is in memory, except in special cases
ANYTHING referring to memory could be changed. That is because
nobody knows where a pointer does not point.
The function `invalidate_memory' removes what is necessary.
The special cases are when the address is constant or is
a constant plus a fixed register such as the frame pointer
or a static chain pointer. When such addresses are stored in,
we can tell exactly which other such addresses must be invalidated
due to overlap. `invalidate' does this.
All expressions that refer to non-constant
memory addresses are also invalidated. `invalidate_memory' does this.
2. If the value changing is a register, all expressions
containing references to that register, and only those,
must be removed.
Because searching the entire hash table for expressions that contain
a register is very slow, we try to figure out when it isn't necessary.
Precisely, this is necessary only when expressions have been
entered in the hash table using this register, and then the value has
changed, and then another expression wants to be added to refer to
the register's new value. This sequence of circumstances is rare
within any one basic block.
The vectors `reg_tick' and `reg_in_table' are used to detect this case.
reg_tick[i] is incremented whenever a value is stored in register i.
reg_in_table[i] holds -1 if no references to register i have been
entered in the table; otherwise, it contains the value reg_tick[i] had
when the references were entered. If we want to enter a reference
and reg_in_table[i] != reg_tick[i], we must scan and remove old references.
Until we want to enter a new entry, the mere fact that the two vectors
don't match makes the entries be ignored if anyone tries to match them.
Registers themselves are entered in the hash table as well as in
the equivalent-register chains. However, the vectors `reg_tick'
and `reg_in_table' do not apply to expressions which are simple
register references. These expressions are removed from the table
immediately when they become invalid, and this can be done even if
we do not immediately search for all the expressions that refer to
the register.
A CLOBBER rtx in an instruction invalidates its operand for further
reuse. A CLOBBER or SET rtx whose operand is a MEM:BLK
invalidates everything that resides in memory.
Related expressions:
Constant expressions that differ only by an additive integer
are called related. When a constant expression is put in
the table, the related expression with no constant term
is also entered. These are made to point at each other
so that it is possible to find out if there exists any
register equivalent to an expression related to a given expression. */
/* One plus largest register number used in this function. */
static int max_reg;
/* One plus largest instruction UID used in this function at time of
cse_main call. */
static int max_insn_uid;
/* Length of qty_table vector. We know in advance we will not need
a quantity number this big. */
static int max_qty;
/* Next quantity number to be allocated.
This is 1 + the largest number needed so far. */
static int next_qty;
/* Per-qty information tracking.
`first_reg' and `last_reg' track the head and tail of the
chain of registers which currently contain this quantity.
`mode' contains the machine mode of this quantity.
`const_rtx' holds the rtx of the constant value of this
quantity, if known. A summations of the frame/arg pointer
and a constant can also be entered here. When this holds
a known value, `const_insn' is the insn which stored the
constant value.
`comparison_{code,const,qty}' are used to track when a
comparison between a quantity and some constant or register has
been passed. In such a case, we know the results of the comparison
in case we see it again. These members record a comparison that
is known to be true. `comparison_code' holds the rtx code of such
a comparison, else it is set to UNKNOWN and the other two
comparison members are undefined. `comparison_const' holds
the constant being compared against, or zero if the comparison
is not against a constant. `comparison_qty' holds the quantity
being compared against when the result is known. If the comparison
is not with a register, `comparison_qty' is -1. */
struct qty_table_elem
{
rtx const_rtx;
rtx const_insn;
rtx comparison_const;
int comparison_qty;
unsigned int first_reg, last_reg;
enum machine_mode mode;
enum rtx_code comparison_code;
};
/* The table of all qtys, indexed by qty number. */
static struct qty_table_elem *qty_table;
#ifdef HAVE_cc0
/* For machines that have a CC0, we do not record its value in the hash
table since its use is guaranteed to be the insn immediately following
its definition and any other insn is presumed to invalidate it.
Instead, we store below the value last assigned to CC0. If it should
happen to be a constant, it is stored in preference to the actual
assigned value. In case it is a constant, we store the mode in which
the constant should be interpreted. */
static rtx prev_insn_cc0;
static enum machine_mode prev_insn_cc0_mode;
#endif
/* Previous actual insn. 0 if at first insn of basic block. */
static rtx prev_insn;
/* Insn being scanned. */
static rtx this_insn;
/* Index by register number, gives the number of the next (or
previous) register in the chain of registers sharing the same
value.
Or -1 if this register is at the end of the chain.
If reg_qty[N] == N, reg_eqv_table[N].next is undefined. */
/* Per-register equivalence chain. */
struct reg_eqv_elem
{
int next, prev;
};
/* The table of all register equivalence chains. */
static struct reg_eqv_elem *reg_eqv_table;
struct cse_reg_info
{
/* Next in hash chain. */
struct cse_reg_info *hash_next;
/* The next cse_reg_info structure in the free or used list. */
struct cse_reg_info *next;
/* Search key */
unsigned int regno;
/* The quantity number of the register's current contents. */
int reg_qty;
/* The number of times the register has been altered in the current
basic block. */
int reg_tick;
/* The REG_TICK value at which rtx's containing this register are
valid in the hash table. If this does not equal the current
reg_tick value, such expressions existing in the hash table are
invalid. */
int reg_in_table;
/* The SUBREG that was set when REG_TICK was last incremented. Set
to -1 if the last store was to the whole register, not a subreg. */
unsigned int subreg_ticked;
};
/* A free list of cse_reg_info entries. */
static struct cse_reg_info *cse_reg_info_free_list;
/* A used list of cse_reg_info entries. */
static struct cse_reg_info *cse_reg_info_used_list;
static struct cse_reg_info *cse_reg_info_used_list_end;
/* A mapping from registers to cse_reg_info data structures. */
#define REGHASH_SHIFT 7
#define REGHASH_SIZE (1 << REGHASH_SHIFT)
#define REGHASH_MASK (REGHASH_SIZE - 1)
static struct cse_reg_info *reg_hash[REGHASH_SIZE];
#define REGHASH_FN(REGNO) \
(((REGNO) ^ ((REGNO) >> REGHASH_SHIFT)) & REGHASH_MASK)
/* The last lookup we did into the cse_reg_info_tree. This allows us
to cache repeated lookups. */
static unsigned int cached_regno;
static struct cse_reg_info *cached_cse_reg_info;
/* A HARD_REG_SET containing all the hard registers for which there is
currently a REG expression in the hash table. Note the difference
from the above variables, which indicate if the REG is mentioned in some
expression in the table. */
static HARD_REG_SET hard_regs_in_table;
/* CUID of insn that starts the basic block currently being cse-processed. */
static int cse_basic_block_start;
/* CUID of insn that ends the basic block currently being cse-processed. */
static int cse_basic_block_end;
/* Vector mapping INSN_UIDs to cuids.
The cuids are like uids but increase monotonically always.
We use them to see whether a reg is used outside a given basic block. */
static int *uid_cuid;
/* Highest UID in UID_CUID. */
static int max_uid;
/* Get the cuid of an insn. */
#define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
/* Nonzero if this pass has made changes, and therefore it's
worthwhile to run the garbage collector. */
static int cse_altered;
/* Nonzero if cse has altered conditional jump insns
in such a way that jump optimization should be redone. */
static int cse_jumps_altered;
/* Nonzero if we put a LABEL_REF into the hash table for an INSN without a
REG_LABEL, we have to rerun jump after CSE to put in the note. */
static int recorded_label_ref;
/* canon_hash stores 1 in do_not_record
if it notices a reference to CC0, PC, or some other volatile
subexpression. */
static int do_not_record;
#ifdef LOAD_EXTEND_OP
/* Scratch rtl used when looking for load-extended copy of a MEM. */
static rtx memory_extend_rtx;
#endif
/* canon_hash stores 1 in hash_arg_in_memory
if it notices a reference to memory within the expression being hashed. */
static int hash_arg_in_memory;
/* The hash table contains buckets which are chains of `struct table_elt's,
each recording one expression's information.
That expression is in the `exp' field.
The canon_exp field contains a canonical (from the point of view of
alias analysis) version of the `exp' field.
Those elements with the same hash code are chained in both directions
through the `next_same_hash' and `prev_same_hash' fields.
Each set of expressions with equivalent values
are on a two-way chain through the `next_same_value'
and `prev_same_value' fields, and all point with
the `first_same_value' field at the first element in
that chain. The chain is in order of increasing cost.
Each element's cost value is in its `cost' field.
The `in_memory' field is nonzero for elements that
involve any reference to memory. These elements are removed
whenever a write is done to an unidentified location in memory.
To be safe, we assume that a memory address is unidentified unless
the address is either a symbol constant or a constant plus
the frame pointer or argument pointer.
The `related_value' field is used to connect related expressions
(that differ by adding an integer).
The related expressions are chained in a circular fashion.
`related_value' is zero for expressions for which this
chain is not useful.
The `cost' field stores the cost of this element's expression.
The `regcost' field stores the value returned by approx_reg_cost for
this element's expression.
The `is_const' flag is set if the element is a constant (including
a fixed address).
The `flag' field is used as a temporary during some search routines.
The `mode' field is usually the same as GET_MODE (`exp'), but
if `exp' is a CONST_INT and has no machine mode then the `mode'
field is the mode it was being used as. Each constant is
recorded separately for each mode it is used with. */
struct table_elt
{
rtx exp;
rtx canon_exp;
struct table_elt *next_same_hash;
struct table_elt *prev_same_hash;
struct table_elt *next_same_value;
struct table_elt *prev_same_value;
struct table_elt *first_same_value;
struct table_elt *related_value;
int cost;
int regcost;
enum machine_mode mode;
char in_memory;
char is_const;
char flag;
};
/* We don't want a lot of buckets, because we rarely have very many
things stored in the hash table, and a lot of buckets slows
down a lot of loops that happen frequently. */
#define HASH_SHIFT 5
#define HASH_SIZE (1 << HASH_SHIFT)
#define HASH_MASK (HASH_SIZE - 1)
/* Compute hash code of X in mode M. Special-case case where X is a pseudo
register (hard registers may require `do_not_record' to be set). */
#define HASH(X, M) \
((GET_CODE (X) == REG && REGNO (X) >= FIRST_PSEUDO_REGISTER \
? (((unsigned) REG << 7) + (unsigned) REG_QTY (REGNO (X))) \
: canon_hash (X, M)) & HASH_MASK)
/* Determine whether register number N is considered a fixed register for the
purpose of approximating register costs.
It is desirable to replace other regs with fixed regs, to reduce need for
non-fixed hard regs.
A reg wins if it is either the frame pointer or designated as fixed. */
#define FIXED_REGNO_P(N) \
((N) == FRAME_POINTER_REGNUM || (N) == HARD_FRAME_POINTER_REGNUM \
|| fixed_regs[N] || global_regs[N])
/* Compute cost of X, as stored in the `cost' field of a table_elt. Fixed
hard registers and pointers into the frame are the cheapest with a cost
of 0. Next come pseudos with a cost of one and other hard registers with
a cost of 2. Aside from these special cases, call `rtx_cost'. */
#define CHEAP_REGNO(N) \
((N) == FRAME_POINTER_REGNUM || (N) == HARD_FRAME_POINTER_REGNUM \
|| (N) == STACK_POINTER_REGNUM || (N) == ARG_POINTER_REGNUM \
|| ((N) >= FIRST_VIRTUAL_REGISTER && (N) <= LAST_VIRTUAL_REGISTER) \
|| ((N) < FIRST_PSEUDO_REGISTER \
&& FIXED_REGNO_P (N) && REGNO_REG_CLASS (N) != NO_REGS))
#define COST(X) (GET_CODE (X) == REG ? 0 : notreg_cost (X, SET))
#define COST_IN(X,OUTER) (GET_CODE (X) == REG ? 0 : notreg_cost (X, OUTER))
/* Get the info associated with register N. */
#define GET_CSE_REG_INFO(N) \
(((N) == cached_regno && cached_cse_reg_info) \
? cached_cse_reg_info : get_cse_reg_info ((N)))
/* Get the number of times this register has been updated in this
basic block. */
#define REG_TICK(N) ((GET_CSE_REG_INFO (N))->reg_tick)
/* Get the point at which REG was recorded in the table. */
#define REG_IN_TABLE(N) ((GET_CSE_REG_INFO (N))->reg_in_table)
/* Get the SUBREG set at the last increment to REG_TICK (-1 if not a
SUBREG). */
#define SUBREG_TICKED(N) ((GET_CSE_REG_INFO (N))->subreg_ticked)
/* Get the quantity number for REG. */
#define REG_QTY(N) ((GET_CSE_REG_INFO (N))->reg_qty)
/* Determine if the quantity number for register X represents a valid index
into the qty_table. */
#define REGNO_QTY_VALID_P(N) (REG_QTY (N) != (int) (N))
static struct table_elt *table[HASH_SIZE];
/* Chain of `struct table_elt's made so far for this function
but currently removed from the table. */
static struct table_elt *free_element_chain;
/* Number of `struct table_elt' structures made so far for this function. */
static int n_elements_made;
/* Maximum value `n_elements_made' has had so far in this compilation
for functions previously processed. */
static int max_elements_made;
/* Surviving equivalence class when two equivalence classes are merged
by recording the effects of a jump in the last insn. Zero if the
last insn was not a conditional jump. */
static struct table_elt *last_jump_equiv_class;
/* Set to the cost of a constant pool reference if one was found for a
symbolic constant. If this was found, it means we should try to
convert constants into constant pool entries if they don't fit in
the insn. */
static int constant_pool_entries_cost;
/* Define maximum length of a branch path. */
#define PATHLENGTH 10
/* This data describes a block that will be processed by cse_basic_block. */
struct cse_basic_block_data
{
/* Lowest CUID value of insns in block. */
int low_cuid;
/* Highest CUID value of insns in block. */
int high_cuid;
/* Total number of SETs in block. */
int nsets;
/* Last insn in the block. */
rtx last;
/* Size of current branch path, if any. */
int path_size;
/* Current branch path, indicating which branches will be taken. */
struct branch_path
{
/* The branch insn. */
rtx branch;
/* Whether it should be taken or not. AROUND is the same as taken
except that it is used when the destination label is not preceded
by a BARRIER. */
enum taken {TAKEN, NOT_TAKEN, AROUND} status;
} path[PATHLENGTH];
};
/* Nonzero if X has the form (PLUS frame-pointer integer). We check for
virtual regs here because the simplify_*_operation routines are called
by integrate.c, which is called before virtual register instantiation.
?!? FIXED_BASE_PLUS_P and NONZERO_BASE_PLUS_P need to move into
a header file so that their definitions can be shared with the
simplification routines in simplify-rtx.c. Until then, do not
change these macros without also changing the copy in simplify-rtx.c. */
#define FIXED_BASE_PLUS_P(X) \
((X) == frame_pointer_rtx || (X) == hard_frame_pointer_rtx \
|| ((X) == arg_pointer_rtx && fixed_regs[ARG_POINTER_REGNUM])\
|| (X) == virtual_stack_vars_rtx \
|| (X) == virtual_incoming_args_rtx \
|| (GET_CODE (X) == PLUS && GET_CODE (XEXP (X, 1)) == CONST_INT \
&& (XEXP (X, 0) == frame_pointer_rtx \
|| XEXP (X, 0) == hard_frame_pointer_rtx \
|| ((X) == arg_pointer_rtx \
&& fixed_regs[ARG_POINTER_REGNUM]) \
|| XEXP (X, 0) == virtual_stack_vars_rtx \
|| XEXP (X, 0) == virtual_incoming_args_rtx)) \
|| GET_CODE (X) == ADDRESSOF)
/* Similar, but also allows reference to the stack pointer.
This used to include FIXED_BASE_PLUS_P, however, we can't assume that
arg_pointer_rtx by itself is nonzero, because on at least one machine,
the i960, the arg pointer is zero when it is unused. */
#define NONZERO_BASE_PLUS_P(X) \
((X) == frame_pointer_rtx || (X) == hard_frame_pointer_rtx \
|| (X) == virtual_stack_vars_rtx \
|| (X) == virtual_incoming_args_rtx \
|| (GET_CODE (X) == PLUS && GET_CODE (XEXP (X, 1)) == CONST_INT \
&& (XEXP (X, 0) == frame_pointer_rtx \
|| XEXP (X, 0) == hard_frame_pointer_rtx \
|| ((X) == arg_pointer_rtx \
&& fixed_regs[ARG_POINTER_REGNUM]) \
|| XEXP (X, 0) == virtual_stack_vars_rtx \
|| XEXP (X, 0) == virtual_incoming_args_rtx)) \
|| (X) == stack_pointer_rtx \
|| (X) == virtual_stack_dynamic_rtx \
|| (X) == virtual_outgoing_args_rtx \
|| (GET_CODE (X) == PLUS && GET_CODE (XEXP (X, 1)) == CONST_INT \
&& (XEXP (X, 0) == stack_pointer_rtx \
|| XEXP (X, 0) == virtual_stack_dynamic_rtx \
|| XEXP (X, 0) == virtual_outgoing_args_rtx)) \
|| GET_CODE (X) == ADDRESSOF)
static int notreg_cost PARAMS ((rtx, enum rtx_code));
static int approx_reg_cost_1 PARAMS ((rtx *, void *));
static int approx_reg_cost PARAMS ((rtx));
static int preferrable PARAMS ((int, int, int, int));
static void new_basic_block PARAMS ((void));
static void make_new_qty PARAMS ((unsigned int, enum machine_mode));
static void make_regs_eqv PARAMS ((unsigned int, unsigned int));
static void delete_reg_equiv PARAMS ((unsigned int));
static int mention_regs PARAMS ((rtx));
static int insert_regs PARAMS ((rtx, struct table_elt *, int));
static void remove_from_table PARAMS ((struct table_elt *, unsigned));
static struct table_elt *lookup PARAMS ((rtx, unsigned, enum machine_mode)),
*lookup_for_remove PARAMS ((rtx, unsigned, enum machine_mode));
static rtx lookup_as_function PARAMS ((rtx, enum rtx_code));
static struct table_elt *insert PARAMS ((rtx, struct table_elt *, unsigned,
enum machine_mode));
static void merge_equiv_classes PARAMS ((struct table_elt *,
struct table_elt *));
static void invalidate PARAMS ((rtx, enum machine_mode));
static int cse_rtx_varies_p PARAMS ((rtx, int));
static void remove_invalid_refs PARAMS ((unsigned int));
static void remove_invalid_subreg_refs PARAMS ((unsigned int, unsigned int,
enum machine_mode));
static void rehash_using_reg PARAMS ((rtx));
static void invalidate_memory PARAMS ((void));
static void invalidate_for_call PARAMS ((void));
static rtx use_related_value PARAMS ((rtx, struct table_elt *));
static unsigned canon_hash PARAMS ((rtx, enum machine_mode));
static unsigned canon_hash_string PARAMS ((const char *));
static unsigned safe_hash PARAMS ((rtx, enum machine_mode));
static int exp_equiv_p PARAMS ((rtx, rtx, int, int));
static rtx canon_reg PARAMS ((rtx, rtx));
static void find_best_addr PARAMS ((rtx, rtx *, enum machine_mode));
static enum rtx_code find_comparison_args PARAMS ((enum rtx_code, rtx *, rtx *,
enum machine_mode *,
enum machine_mode *));
static rtx fold_rtx PARAMS ((rtx, rtx));
static rtx equiv_constant PARAMS ((rtx));
static void record_jump_equiv PARAMS ((rtx, int));
static void record_jump_cond PARAMS ((enum rtx_code, enum machine_mode,
rtx, rtx, int));
static void cse_insn PARAMS ((rtx, rtx));
static int addr_affects_sp_p PARAMS ((rtx));
static void invalidate_from_clobbers PARAMS ((rtx));
static rtx cse_process_notes PARAMS ((rtx, rtx));
static void cse_around_loop PARAMS ((rtx));
static void invalidate_skipped_set PARAMS ((rtx, rtx, void *));
static void invalidate_skipped_block PARAMS ((rtx));
static void cse_check_loop_start PARAMS ((rtx, rtx, void *));
static void cse_set_around_loop PARAMS ((rtx, rtx, rtx));
static rtx cse_basic_block PARAMS ((rtx, rtx, struct branch_path *, int));
static void count_reg_usage PARAMS ((rtx, int *, rtx, int));
static int check_for_label_ref PARAMS ((rtx *, void *));
extern void dump_class PARAMS ((struct table_elt*));
static struct cse_reg_info * get_cse_reg_info PARAMS ((unsigned int));
static int check_dependence PARAMS ((rtx *, void *));
static void flush_hash_table PARAMS ((void));
static bool insn_live_p PARAMS ((rtx, int *));
static bool set_live_p PARAMS ((rtx, rtx, int *));
static bool dead_libcall_p PARAMS ((rtx, int *));
static int cse_change_cc_mode PARAMS ((rtx *, void *));
static void cse_change_cc_mode_insns PARAMS ((rtx, rtx, rtx));
static enum machine_mode cse_cc_succs PARAMS ((basic_block, rtx, rtx, int));
/* Dump the expressions in the equivalence class indicated by CLASSP.
This function is used only for debugging. */
void
dump_class (classp)
struct table_elt *classp;
{
struct table_elt *elt;
fprintf (stderr, "Equivalence chain for ");
print_rtl (stderr, classp->exp);
fprintf (stderr, ": \n");
for (elt = classp->first_same_value; elt; elt = elt->next_same_value)
{
print_rtl (stderr, elt->exp);
fprintf (stderr, "\n");
}
}
/* Subroutine of approx_reg_cost; called through for_each_rtx. */
static int
approx_reg_cost_1 (xp, data)
rtx *xp;
void *data;
{
rtx x = *xp;
int *cost_p = data;
if (x && GET_CODE (x) == REG)
{
unsigned int regno = REGNO (x);
if (! CHEAP_REGNO (regno))
{
if (regno < FIRST_PSEUDO_REGISTER)
{
if (SMALL_REGISTER_CLASSES)
return 1;
*cost_p += 2;
}
else
*cost_p += 1;
}
}
return 0;
}
/* Return an estimate of the cost of the registers used in an rtx.
This is mostly the number of different REG expressions in the rtx;
however for some exceptions like fixed registers we use a cost of
0. If any other hard register reference occurs, return MAX_COST. */
static int
approx_reg_cost (x)
rtx x;
{
int cost = 0;
if (for_each_rtx (&x, approx_reg_cost_1, (void *) &cost))
return MAX_COST;
return cost;
}
/* Return a negative value if an rtx A, whose costs are given by COST_A
and REGCOST_A, is more desirable than an rtx B.
Return a positive value if A is less desirable, or 0 if the two are
equally good. */
static int
preferrable (cost_a, regcost_a, cost_b, regcost_b)
int cost_a, regcost_a, cost_b, regcost_b;
{
/* First, get rid of cases involving expressions that are entirely
unwanted. */
if (cost_a != cost_b)
{
if (cost_a == MAX_COST)
return 1;
if (cost_b == MAX_COST)
return -1;
}
/* Avoid extending lifetimes of hardregs. */
if (regcost_a != regcost_b)
{
if (regcost_a == MAX_COST)
return 1;
if (regcost_b == MAX_COST)
return -1;
}
/* Normal operation costs take precedence. */
if (cost_a != cost_b)
return cost_a - cost_b;
/* Only if these are identical consider effects on register pressure. */
if (regcost_a != regcost_b)
return regcost_a - regcost_b;
return 0;
}
/* Internal function, to compute cost when X is not a register; called
from COST macro to keep it simple. */
static int
notreg_cost (x, outer)
rtx x;
enum rtx_code outer;
{
return ((GET_CODE (x) == SUBREG
&& GET_CODE (SUBREG_REG (x)) == REG
&& GET_MODE_CLASS (GET_MODE (x)) == MODE_INT
&& GET_MODE_CLASS (GET_MODE (SUBREG_REG (x))) == MODE_INT
&& (GET_MODE_SIZE (GET_MODE (x))
< GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
&& subreg_lowpart_p (x)
&& TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (GET_MODE (x)),
GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x)))))
? 0
: rtx_cost (x, outer) * 2);
}
/* Return an estimate of the cost of computing rtx X.
One use is in cse, to decide which expression to keep in the hash table.
Another is in rtl generation, to pick the cheapest way to multiply.
Other uses like the latter are expected in the future. */
int
rtx_cost (x, outer_code)
rtx x;
enum rtx_code outer_code ATTRIBUTE_UNUSED;
{
int i, j;
enum rtx_code code;
const char *fmt;
int total;
if (x == 0)
return 0;
/* Compute the default costs of certain things.
Note that RTX_COSTS can override the defaults. */
code = GET_CODE (x);
switch (code)
{
case MULT:
total = COSTS_N_INSNS (5);
break;
case DIV:
case UDIV:
case MOD:
case UMOD:
total = COSTS_N_INSNS (7);
break;
case USE:
/* Used in loop.c and combine.c as a marker. */
total = 0;
break;
default:
total = COSTS_N_INSNS (1);
}
switch (code)
{
case REG:
return 0;
case SUBREG:
/* If we can't tie these modes, make this expensive. The larger
the mode, the more expensive it is. */
if (! MODES_TIEABLE_P (GET_MODE (x), GET_MODE (SUBREG_REG (x))))
return COSTS_N_INSNS (2
+ GET_MODE_SIZE (GET_MODE (x)) / UNITS_PER_WORD);
break;
#ifdef RTX_COSTS
RTX_COSTS (x, code, outer_code);
#endif
#ifdef CONST_COSTS
CONST_COSTS (x, code, outer_code);
#endif
default:
#ifdef DEFAULT_RTX_COSTS
DEFAULT_RTX_COSTS (x, code, outer_code);
#endif
break;
}
/* Sum the costs of the sub-rtx's, plus cost of this operation,
which is already in total. */
fmt = GET_RTX_FORMAT (code);
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
if (fmt[i] == 'e')
total += rtx_cost (XEXP (x, i), code);
else if (fmt[i] == 'E')
for (j = 0; j < XVECLEN (x, i); j++)
total += rtx_cost (XVECEXP (x, i, j), code);
return total;
}
/* Return cost of address expression X.
Expect that X is properly formed address reference. */
int
address_cost (x, mode)
rtx x;
enum machine_mode mode;
{
/* The ADDRESS_COST macro does not deal with ADDRESSOF nodes. But,
during CSE, such nodes are present. Using an ADDRESSOF node which
refers to the address of a REG is a good thing because we can then
turn (MEM (ADDRESSSOF (REG))) into just plain REG. */
if (GET_CODE (x) == ADDRESSOF && REG_P (XEXP ((x), 0)))
return -1;
/* We may be asked for cost of various unusual addresses, such as operands
of push instruction. It is not worthwhile to complicate writing
of ADDRESS_COST macro by such cases. */
if (!memory_address_p (mode, x))
return 1000;
#ifdef ADDRESS_COST
return ADDRESS_COST (x);
#else
return rtx_cost (x, MEM);
#endif
}
static struct cse_reg_info *
get_cse_reg_info (regno)
unsigned int regno;
{
struct cse_reg_info **hash_head = &reg_hash[REGHASH_FN (regno)];
struct cse_reg_info *p;
for (p = *hash_head; p != NULL; p = p->hash_next)
if (p->regno == regno)
break;
if (p == NULL)
{
/* Get a new cse_reg_info structure. */
if (cse_reg_info_free_list)
{
p = cse_reg_info_free_list;
cse_reg_info_free_list = p->next;
}
else
p = (struct cse_reg_info *) xmalloc (sizeof (struct cse_reg_info));
/* Insert into hash table. */
p->hash_next = *hash_head;
*hash_head = p;
/* Initialize it. */
p->reg_tick = 1;
p->reg_in_table = -1;
p->subreg_ticked = -1;
p->reg_qty = regno;
p->regno = regno;
p->next = cse_reg_info_used_list;
cse_reg_info_used_list = p;
if (!cse_reg_info_used_list_end)
cse_reg_info_used_list_end = p;
}
/* Cache this lookup; we tend to be looking up information about the
same register several times in a row. */
cached_regno = regno;
cached_cse_reg_info = p;
return p;
}
/* Clear the hash table and initialize each register with its own quantity,
for a new basic block. */
static void
new_basic_block ()
{
int i;
next_qty = max_reg;
/* Clear out hash table state for this pass. */
memset ((char *) reg_hash, 0, sizeof reg_hash);
if (cse_reg_info_used_list)
{
cse_reg_info_used_list_end->next = cse_reg_info_free_list;
cse_reg_info_free_list = cse_reg_info_used_list;
cse_reg_info_used_list = cse_reg_info_used_list_end = 0;
}
cached_cse_reg_info = 0;
CLEAR_HARD_REG_SET (hard_regs_in_table);
/* The per-quantity values used to be initialized here, but it is
much faster to initialize each as it is made in `make_new_qty'. */
for (i = 0; i < HASH_SIZE; i++)
{
struct table_elt *first;
first = table[i];
if (first != NULL)
{
struct table_elt *last = first;
table[i] = NULL;
while (last->next_same_hash != NULL)
last = last->next_same_hash;
/* Now relink this hash entire chain into
the free element list. */
last->next_same_hash = free_element_chain;
free_element_chain = first;
}
}
prev_insn = 0;
#ifdef HAVE_cc0
prev_insn_cc0 = 0;
#endif
}
/* Say that register REG contains a quantity in mode MODE not in any
register before and initialize that quantity. */
static void
make_new_qty (reg, mode)
unsigned int reg;
enum machine_mode mode;
{
int q;
struct qty_table_elem *ent;
struct reg_eqv_elem *eqv;
if (next_qty >= max_qty)
abort ();
q = REG_QTY (reg) = next_qty++;
ent = &qty_table[q];
ent->first_reg = reg;
ent->last_reg = reg;
ent->mode = mode;
ent->const_rtx = ent->const_insn = NULL_RTX;
ent->comparison_code = UNKNOWN;
eqv = &reg_eqv_table[reg];
eqv->next = eqv->prev = -1;
}
/* Make reg NEW equivalent to reg OLD.
OLD is not changing; NEW is. */
static void
make_regs_eqv (new, old)
unsigned int new, old;
{
unsigned int lastr, firstr;
int q = REG_QTY (old);
struct qty_table_elem *ent;
ent = &qty_table[q];
/* Nothing should become eqv until it has a "non-invalid" qty number. */
if (! REGNO_QTY_VALID_P (old))
abort ();
REG_QTY (new) = q;
firstr = ent->first_reg;
lastr = ent->last_reg;
/* Prefer fixed hard registers to anything. Prefer pseudo regs to other
hard regs. Among pseudos, if NEW will live longer than any other reg
of the same qty, and that is beyond the current basic block,
make it the new canonical replacement for this qty. */
if (! (firstr < FIRST_PSEUDO_REGISTER && FIXED_REGNO_P (firstr))
/* Certain fixed registers might be of the class NO_REGS. This means
that not only can they not be allocated by the compiler, but
they cannot be used in substitutions or canonicalizations
either. */
&& (new >= FIRST_PSEUDO_REGISTER || REGNO_REG_CLASS (new) != NO_REGS)
&& ((new < FIRST_PSEUDO_REGISTER && FIXED_REGNO_P (new))
|| (new >= FIRST_PSEUDO_REGISTER
&& (firstr < FIRST_PSEUDO_REGISTER
|| ((uid_cuid[REGNO_LAST_UID (new)] > cse_basic_block_end
|| (uid_cuid[REGNO_FIRST_UID (new)]
< cse_basic_block_start))
&& (uid_cuid[REGNO_LAST_UID (new)]
> uid_cuid[REGNO_LAST_UID (firstr)]))))))
{
reg_eqv_table[firstr].prev = new;
reg_eqv_table[new].next = firstr;
reg_eqv_table[new].prev = -1;
ent->first_reg = new;
}
else
{
/* If NEW is a hard reg (known to be non-fixed), insert at end.
Otherwise, insert before any non-fixed hard regs that are at the
end. Registers of class NO_REGS cannot be used as an
equivalent for anything. */
while (lastr < FIRST_PSEUDO_REGISTER && reg_eqv_table[lastr].prev >= 0
&& (REGNO_REG_CLASS (lastr) == NO_REGS || ! FIXED_REGNO_P (lastr))
&& new >= FIRST_PSEUDO_REGISTER)
lastr = reg_eqv_table[lastr].prev;
reg_eqv_table[new].next = reg_eqv_table[lastr].next;
if (reg_eqv_table[lastr].next >= 0)
reg_eqv_table[reg_eqv_table[lastr].next].prev = new;
else
qty_table[q].last_reg = new;
reg_eqv_table[lastr].next = new;
reg_eqv_table[new].prev = lastr;
}
}
/* Remove REG from its equivalence class. */
static void
delete_reg_equiv (reg)
unsigned int reg;
{
struct qty_table_elem *ent;
int q = REG_QTY (reg);
int p, n;
/* If invalid, do nothing. */
if (q == (int) reg)
return;
ent = &qty_table[q];
p = reg_eqv_table[reg].prev;
n = reg_eqv_table[reg].next;
if (n != -1)
reg_eqv_table[n].prev = p;
else
ent->last_reg = p;
if (p != -1)
reg_eqv_table[p].next = n;
else
ent->first_reg = n;
REG_QTY (reg) = reg;
}
/* Remove any invalid expressions from the hash table
that refer to any of the registers contained in expression X.
Make sure that newly inserted references to those registers
as subexpressions will be considered valid.
mention_regs is not called when a register itself
is being stored in the table.
Return 1 if we have done something that may have changed the hash code
of X. */
static int
mention_regs (x)
rtx x;
{
enum rtx_code code;
int i, j;
const char *fmt;
int changed = 0;
if (x == 0)
return 0;
code = GET_CODE (x);
if (code == REG)
{
unsigned int regno = REGNO (x);
unsigned int endregno
= regno + (regno >= FIRST_PSEUDO_REGISTER ? 1
: HARD_REGNO_NREGS (regno, GET_MODE (x)));
unsigned int i;
for (i = regno; i < endregno; i++)
{
if (REG_IN_TABLE (i) >= 0 && REG_IN_TABLE (i) != REG_TICK (i))
remove_invalid_refs (i);
REG_IN_TABLE (i) = REG_TICK (i);
SUBREG_TICKED (i) = -1;
}
return 0;
}
/* If this is a SUBREG, we don't want to discard other SUBREGs of the same
pseudo if they don't use overlapping words. We handle only pseudos
here for simplicity. */
if (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG
&& REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER)
{
unsigned int i = REGNO (SUBREG_REG (x));
if (REG_IN_TABLE (i) >= 0 && REG_IN_TABLE (i) != REG_TICK (i))
{
/* If REG_IN_TABLE (i) differs from REG_TICK (i) by one, and
the last store to this register really stored into this
subreg, then remove the memory of this subreg.
Otherwise, remove any memory of the entire register and
all its subregs from the table. */
if (REG_TICK (i) - REG_IN_TABLE (i) > 1
|| SUBREG_TICKED (i) != REGNO (SUBREG_REG (x)))
remove_invalid_refs (i);
else
remove_invalid_subreg_refs (i, SUBREG_BYTE (x), GET_MODE (x));
}
REG_IN_TABLE (i) = REG_TICK (i);
SUBREG_TICKED (i) = REGNO (SUBREG_REG (x));
return 0;
}
/* If X is a comparison or a COMPARE and either operand is a register
that does not have a quantity, give it one. This is so that a later
call to record_jump_equiv won't cause X to be assigned a different
hash code and not found in the table after that call.
It is not necessary to do this here, since rehash_using_reg can
fix up the table later, but doing this here eliminates the need to
call that expensive function in the most common case where the only
use of the register is in the comparison. */
if (code == COMPARE || GET_RTX_CLASS (code) == '<')
{
if (GET_CODE (XEXP (x, 0)) == REG
&& ! REGNO_QTY_VALID_P (REGNO (XEXP (x, 0))))
if (insert_regs (XEXP (x, 0), NULL, 0))
{
rehash_using_reg (XEXP (x, 0));
changed = 1;
}
if (GET_CODE (XEXP (x, 1)) == REG
&& ! REGNO_QTY_VALID_P (REGNO (XEXP (x, 1))))
if (insert_regs (XEXP (x, 1), NULL, 0))
{
rehash_using_reg (XEXP (x, 1));
changed = 1;
}
}
fmt = GET_RTX_FORMAT (code);
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
if (fmt[i] == 'e')
changed |= mention_regs (XEXP (x, i));
else if (fmt[i] == 'E')
for (j = 0; j < XVECLEN (x, i); j++)
changed |= mention_regs (XVECEXP (x, i, j));
return changed;
}
/* Update the register quantities for inserting X into the hash table
with a value equivalent to CLASSP.
(If the class does not contain a REG, it is irrelevant.)
If MODIFIED is nonzero, X is a destination; it is being modified.
Note that delete_reg_equiv should be called on a register
before insert_regs is done on that register with MODIFIED != 0.
Nonzero value means that elements of reg_qty have changed
so X's hash code may be different. */
static int
insert_regs (x, classp, modified)
rtx x;
struct table_elt *classp;
int modified;
{
if (GET_CODE (x) == REG)
{
unsigned int regno = REGNO (x);
int qty_valid;
/* If REGNO is in the equivalence table already but is of the
wrong mode for that equivalence, don't do anything here. */
qty_valid = REGNO_QTY_VALID_P (regno);
if (qty_valid)
{
struct qty_table_elem *ent = &qty_table[REG_QTY (regno)];
if (ent->mode != GET_MODE (x))
return 0;
}
if (modified || ! qty_valid)
{
if (classp)
for (classp = classp->first_same_value;
classp != 0;
classp = classp->next_same_value)
if (GET_CODE (classp->exp) == REG
&& GET_MODE (classp->exp) == GET_MODE (x))
{
make_regs_eqv (regno, REGNO (classp->exp));
return 1;
}
/* Mention_regs for a SUBREG checks if REG_TICK is exactly one larger
than REG_IN_TABLE to find out if there was only a single preceding
invalidation - for the SUBREG - or another one, which would be
for the full register. However, if we find here that REG_TICK
indicates that the register is invalid, it means that it has
been invalidated in a separate operation. The SUBREG might be used
now (then this is a recursive call), or we might use the full REG
now and a SUBREG of it later. So bump up REG_TICK so that
mention_regs will do the right thing. */
if (! modified
&& REG_IN_TABLE (regno) >= 0
&& REG_TICK (regno) == REG_IN_TABLE (regno) + 1)
REG_TICK (regno)++;
make_new_qty (regno, GET_MODE (x));
return 1;
}
return 0;
}
/* If X is a SUBREG, we will likely be inserting the inner register in the
table. If that register doesn't have an assigned quantity number at
this point but does later, the insertion that we will be doing now will
not be accessible because its hash code will have changed. So assign
a quantity number now. */
else if (GET_CODE (x) == SUBREG && GET_CODE (SUBREG_REG (x)) == REG
&& ! REGNO_QTY_VALID_P (REGNO (SUBREG_REG (x))))
{
insert_regs (SUBREG_REG (x), NULL, 0);
mention_regs (x);
return 1;
}
else
return mention_regs (x);
}
/* Look in or update the hash table. */
/* Remove table element ELT from use in the table.
HASH is its hash code, made using the HASH macro.
It's an argument because often that is known in advance
and we save much time not recomputing it. */
static void
remove_from_table (elt, hash)
struct table_elt *elt;
unsigned hash;
{
if (elt == 0)
return;
/* Mark this element as removed. See cse_insn. */
elt->first_same_value = 0;
/* Remove the table element from its equivalence class. */
{
struct table_elt *prev = elt->prev_same_value;
struct table_elt *next = elt->next_same_value;
if (next)
next->prev_same_value = prev;
if (prev)
prev->next_same_value = next;
else
{
struct table_elt *newfirst = next;
while (next)
{
next->first_same_value = newfirst;
next = next->next_same_value;
}
}
}
/* Remove the table element from its hash bucket. */
{
struct table_elt *prev = elt->prev_same_hash;
struct table_elt *next = elt->next_same_hash;
if (next)
next->prev_same_hash = prev;
if (prev)
prev->next_same_hash = next;
else if (table[hash] == elt)
table[hash] = next;
else
{
/* This entry is not in the proper hash bucket. This can happen
when two classes were merged by `merge_equiv_classes'. Search
for the hash bucket that it heads. This happens only very
rarely, so the cost is acceptable. */
for (hash = 0; hash < HASH_SIZE; hash++)
if (table[hash] == elt)
table[hash] = next;
}
}
/* Remove the table element from its related-value circular chain. */
if (elt->related_value != 0 && elt->related_value != elt)
{
struct table_elt *p = elt->related_value;
while (p->related_value != elt)
p = p->related_value;
p->related_value = elt->related_value;
if (p->related_value == p)
p->related_value = 0;
}
/* Now add it to the free element chain. */
elt->next_same_hash = free_element_chain;
free_element_chain = elt;
}
/* Look up X in the hash table and return its table element,
or 0 if X is not in the table.
MODE is the machine-mode of X, or if X is an integer constant
with VOIDmode then MODE is the mode with which X will be used.
Here we are satisfied to find an expression whose tree structure
looks like X. */
static struct table_elt *
lookup (x, hash, mode)
rtx x;
unsigned hash;
enum machine_mode mode;
{
struct table_elt *p;
for (p = table[hash]; p; p = p->next_same_hash)
if (mode == p->mode && ((x == p->exp && GET_CODE (x) == REG)
|| exp_equiv_p (x, p->exp, GET_CODE (x) != REG, 0)))
return p;
return 0;
}
/* Like `lookup' but don't care whether the table element uses invalid regs.
Also ignore discrepancies in the machine mode of a register. */
static struct table_elt *
lookup_for_remove (x, hash, mode)
rtx x;
unsigned hash;
enum machine_mode mode;
{
struct table_elt *p;
if (GET_CODE (x) == REG)
{
unsigned int regno = REGNO (x);
/* Don't check the machine mode when comparing registers;
invalidating (REG:SI 0) also invalidates (REG:DF 0). */
for (p = table[hash]; p; p = p->next_same_hash)
if (GET_CODE (p->exp) == REG
&& REGNO (p->exp) == regno)
return p;
}
else
{
for (p = table[hash]; p; p = p->next_same_hash)
if (mode == p->mode && (x == p->exp || exp_equiv_p (x, p->exp, 0, 0)))
return p;
}
return 0;
}
/* Look for an expression equivalent to X and with code CODE.
If one is found, return that expression. */
static rtx
lookup_as_function (x, code)
rtx x;
enum rtx_code code;
{
struct table_elt *p
= lookup (x, safe_hash (x, VOIDmode) & HASH_MASK, GET_MODE (x));
/* If we are looking for a CONST_INT, the mode doesn't really matter, as
long as we are narrowing. So if we looked in vain for a mode narrower
than word_mode before, look for word_mode now. */
if (p == 0 && code == CONST_INT
&& GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (word_mode))
{
x = copy_rtx (x);
PUT_MODE (x, word_mode);
p = lookup (x, safe_hash (x, VOIDmode) & HASH_MASK, word_mode);
}
if (p == 0)
return 0;
for (p = p->first_same_value; p; p = p->next_same_value)
if (GET_CODE (p->exp) == code
/* Make sure this is a valid entry in the table. */
&& exp_equiv_p (p->exp, p->exp, 1, 0))
return p->exp;
return 0;
}
/* Insert X in the hash table, assuming HASH is its hash code
and CLASSP is an element of the class it should go in
(or 0 if a new class should be made).
It is inserted at the proper position to keep the class in
the order cheapest first.
MODE is the machine-mode of X, or if X is an integer constant
with VOIDmode then MODE is the mode with which X will be used.
For elements of equal cheapness, the most recent one
goes in front, except that the first element in the list
remains first unless a cheaper element is added. The order of
pseudo-registers does not matter, as canon_reg will be called to
find the cheapest when a register is retrieved from the table.
The in_memory field in the hash table element is set to 0.
The caller must set it nonzero if appropriate.
You should call insert_regs (X, CLASSP, MODIFY) before calling here,
and if insert_regs returns a nonzero value
you must then recompute its hash code before calling here.
If necessary, update table showing constant values of quantities. */
#define CHEAPER(X, Y) \
(preferrable ((X)->cost, (X)->regcost, (Y)->cost, (Y)->regcost) < 0)
static struct table_elt *
insert (x, classp, hash, mode)
rtx x;
struct table_elt *classp;
unsigned hash;
enum machine_mode mode;
{
struct table_elt *elt;
/* If X is a register and we haven't made a quantity for it,
something is wrong. */
if (GET_CODE (x) == REG && ! REGNO_QTY_VALID_P (REGNO (x)))
abort ();
/* If X is a hard register, show it is being put in the table. */
if (GET_CODE (x) == REG && REGNO (x) < FIRST_PSEUDO_REGISTER)
{
unsigned int regno = REGNO (x);
unsigned int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (x));
unsigned int i;
for (i = regno; i < endregno; i++)
SET_HARD_REG_BIT (hard_regs_in_table, i);
}
/* Put an element for X into the right hash bucket. */
elt = free_element_chain;
if (elt)
free_element_chain = elt->next_same_hash;
else
{
n_elements_made++;
elt = (struct table_elt *) xmalloc (sizeof (struct table_elt));
}
elt->exp = x;
elt->canon_exp = NULL_RTX;
elt->cost = COST (x);
elt->regcost = approx_reg_cost (x);
elt->next_same_value = 0;
elt->prev_same_value = 0;
elt->next_same_hash = table[hash];
elt->prev_same_hash = 0;
elt->related_value = 0;
elt->in_memory = 0;
elt->mode = mode;
elt->is_const = (CONSTANT_P (x)
/* GNU C++ takes advantage of this for `this'
(and other const values). */
|| (GET_CODE (x) == REG
&& RTX_UNCHANGING_P (x)
&& REGNO (x) >= FIRST_PSEUDO_REGISTER)
|| FIXED_BASE_PLUS_P (x));
if (table[hash])
table[hash]->prev_same_hash = elt;
table[hash] = elt;
/* Put it into the proper value-class. */
if (classp)
{
classp = classp->first_same_value;
if (CHEAPER (elt, classp))
/* Insert at the head of the class */
{
struct table_elt *p;
elt->next_same_value = classp;
classp->prev_same_value = elt;
elt->first_same_value = elt;
for (p = classp; p; p = p->next_same_value)
p->first_same_value = elt;
}
else
{
/* Insert not at head of the class. */
/* Put it after the last element cheaper than X. */
struct table_elt *p, *next;
for (p = classp; (next = p->next_same_value) && CHEAPER (next, elt);
p = next);
/* Put it after P and before NEXT. */
elt->next_same_value = next;
if (next)
next->prev_same_value = elt;
elt->prev_same_value = p;
p->next_same_value = elt;
elt->first_same_value = classp;
}
}
else
elt->first_same_value = elt;
/* If this is a constant being set equivalent to a register or a register
being set equivalent to a constant, note the constant equivalence.
If this is a constant, it cannot be equivalent to a different constant,
and a constant is the only thing that can be cheaper than a register. So
we know the register is the head of the class (before the constant was
inserted).
If this is a register that is not already known equivalent to a
constant, we must check the entire class.
If this is a register that is already known equivalent to an insn,
update the qtys `const_insn' to show that `this_insn' is the latest
insn making that quantity equivalent to the constant. */
if (elt->is_const && classp && GET_CODE (classp->exp) == REG
&& GET_CODE (x) != REG)
{
int exp_q = REG_QTY (REGNO (classp->exp));
struct qty_table_elem *exp_ent = &qty_table[exp_q];
exp_ent->const_rtx = gen_lowpart_if_possible (exp_ent->mode, x);
exp_ent->const_insn = this_insn;
}
else if (GET_CODE (x) == REG
&& classp
&& ! qty_table[REG_QTY (REGNO (x))].const_rtx
&& ! elt->is_const)
{
struct table_elt *p;
for (p = classp; p != 0; p = p->next_same_value)
{
if (p->is_const && GET_CODE (p->exp) != REG)
{
int x_q = REG_QTY (REGNO (x));
struct qty_table_elem *x_ent = &qty_table[x_q];
x_ent->const_rtx
= gen_lowpart_if_possible (GET_MODE (x), p->exp);
x_ent->const_insn = this_insn;
break;
}
}
}
else if (GET_CODE (x) == REG
&& qty_table[REG_QTY (REGNO (x))].const_rtx
&& GET_MODE (x) == qty_table[REG_QTY (REGNO (x))].mode)
qty_table[REG_QTY (REGNO (x))].const_insn = this_insn;
/* If this is a constant with symbolic value,
and it has a term with an explicit integer value,
link it up with related expressions. */
if (GET_CODE (x) == CONST)
{
rtx subexp = get_related_value (x);
unsigned subhash;
struct table_elt *subelt, *subelt_prev;
if (subexp != 0)
{
/* Get the integer-free subexpression in the hash table. */
subhash = safe_hash (subexp, mode) & HASH_MASK;
subelt = lookup (subexp, subhash, mode);
if (subelt == 0)
subelt = insert (subexp, NULL, subhash, mode);
/* Initialize SUBELT's circular chain if it has none. */
if (subelt->related_value == 0)
subelt->related_value = subelt;
/* Find the element in the circular chain that precedes SUBELT. */
subelt_prev = subelt;
while (subelt_prev->related_value != subelt)
subelt_prev = subelt_prev->related_value;
/* Put new ELT into SUBELT's circular chain just before SUBELT.
This way the element that follows SUBELT is the oldest one. */
elt->related_value = subelt_prev->related_value;
subelt_prev->related_value = elt;
}
}
return elt;
}
/* Given two equivalence classes, CLASS1 and CLASS2, put all the entries from
CLASS2 into CLASS1. This is done when we have reached an insn which makes
the two classes equivalent.
CLASS1 will be the surviving class; CLASS2 should not be used after this
call.
Any invalid entries in CLASS2 will not be copied. */
static void
merge_equiv_classes (class1, class2)
struct table_elt *class1, *class2;
{
struct table_elt *elt, *next, *new;
/* Ensure we start with the head of the classes. */
class1 = class1->first_same_value;
class2 = class2->first_same_value;
/* If they were already equal, forget it. */
if (class1 == class2)
return;
for (elt = class2; elt; elt = next)
{
unsigned int hash;
rtx exp = elt->exp;
enum machine_mode mode = elt->mode;
next = elt->next_same_value;
/* Remove old entry, make a new one in CLASS1's class.
Don't do this for invalid entries as we cannot find their
hash code (it also isn't necessary). */
if (GET_CODE (exp) == REG || exp_equiv_p (exp, exp, 1, 0))
{
hash_arg_in_memory = 0;
hash = HASH (exp, mode);
if (GET_CODE (exp) == REG)
delete_reg_equiv (REGNO (exp));
remove_from_table (elt, hash);
if (insert_regs (exp, class1, 0))
{
rehash_using_reg (exp);
hash = HASH (exp, mode);
}
new = insert (exp, class1, hash, mode);
new->in_memory = hash_arg_in_memory;
}
}
}
/* Flush the entire hash table. */
static void
flush_hash_table ()
{
int i;
struct table_elt *p;
for (i = 0; i < HASH_SIZE; i++)
for (p = table[i]; p; p = table[i])
{
/* Note that invalidate can remove elements
after P in the current hash chain. */
if (GET_CODE (p->exp) == REG)
invalidate (p->exp, p->mode);
else
remove_from_table (p, i);
}
}
/* Function called for each rtx to check whether true dependence exist. */
struct check_dependence_data
{
enum machine_mode mode;
rtx exp;
};
static int
check_dependence (x, data)
rtx *x;
void *data;
{
struct check_dependence_data *d = (struct check_dependence_data *) data;
if (*x && GET_CODE (*x) == MEM)
return true_dependence (d->exp, d->mode, *x, cse_rtx_varies_p);
else
return 0;
}
/* Remove from the hash table, or mark as invalid, all expressions whose
values could be altered by storing in X. X is a register, a subreg, or
a memory reference with nonvarying address (because, when a memory
reference with a varying address is stored in, all memory references are
removed by invalidate_memory so specific invalidation is superfluous).
FULL_MODE, if not VOIDmode, indicates that this much should be
invalidated instead of just the amount indicated by the mode of X. This
is only used for bitfield stores into memory.
A nonvarying address may be just a register or just a symbol reference,
or it may be either of those plus a numeric offset. */
static void
invalidate (x, full_mode)
rtx x;
enum machine_mode full_mode;
{
int i;
struct table_elt *p;
switch (GET_CODE (x))
{
case REG:
{
/* If X is a register, dependencies on its contents are recorded
through the qty number mechanism. Just change the qty number of
the register, mark it as invalid for expressions that refer to it,
and remove it itself. */
unsigned int regno = REGNO (x);
unsigned int hash = HASH (x, GET_MODE (x));
/* Remove REGNO from any quantity list it might be on and indicate
that its value might have changed. If it is a pseudo, remove its
entry from the hash table.
For a hard register, we do the first two actions above for any
additional hard registers corresponding to X. Then, if any of these
registers are in the table, we must remove any REG entries that
overlap these registers. */
delete_reg_equiv (regno);
REG_TICK (regno)++;
SUBREG_TICKED (regno) = -1;
if (regno >= FIRST_PSEUDO_REGISTER)
{
/* Because a register can be referenced in more than one mode,
we might have to remove more than one table entry. */
struct table_elt *elt;
while ((elt = lookup_for_remove (x, hash, GET_MODE (x))))
remove_from_table (elt, hash);
}
else
{
HOST_WIDE_INT in_table
= TEST_HARD_REG_BIT (hard_regs_in_table, regno);
unsigned int endregno
= regno + HARD_REGNO_NREGS (regno, GET_MODE (x));
unsigned int tregno, tendregno, rn;
struct table_elt *p, *next;
CLEAR_HARD_REG_BIT (hard_regs_in_table, regno);
for (rn = regno + 1; rn < endregno; rn++)
{
in_table |= TEST_HARD_REG_BIT (hard_regs_in_table, rn);
CLEAR_HARD_REG_BIT (hard_regs_in_table, rn);
delete_reg_equiv (rn);
REG_TICK (rn)++;
SUBREG_TICKED (rn) = -1;
}
if (in_table)
for (hash = 0; hash < HASH_SIZE; hash++)
for (p = table[hash]; p; p = next)
{
next = p->next_same_hash;
if (GET_CODE (p->exp) != REG
|| REGNO (p->exp) >= FIRST_PSEUDO_REGISTER)
continue;
tregno = REGNO (p->exp);
tendregno
= tregno + HARD_REGNO_NREGS (tregno, GET_MODE (p->exp));
if (tendregno > regno && tregno < endregno)
remove_from_table (p, hash);
}
}
}
return;
case SUBREG:
invalidate (SUBREG_REG (x), VOIDmode);
return;
case PARALLEL:
for (i = XVECLEN (x, 0) - 1; i >= 0; --i)
invalidate (XVECEXP (x, 0, i), VOIDmode);
return;
case EXPR_LIST:
/* This is part of a disjoint return value; extract the location in
question ignoring the offset. */
invalidate (XEXP (x, 0), VOIDmode);
return;
case MEM:
/* Calculate the canonical version of X here so that
true_dependence doesn't generate new RTL for X on each call. */
x = canon_rtx (x);
/* Remove all hash table elements that refer to overlapping pieces of
memory. */
if (full_mode == VOIDmode)
full_mode = GET_MODE (x);
for (i = 0; i < HASH_SIZE; i++)
{
struct table_elt *next;
for (p = table[i]; p; p = next)
{
next = p->next_same_hash;
if (p->in_memory)
{
struct check_dependence_data d;
/* Just canonicalize the expression once;
otherwise each time we call invalidate
true_dependence will canonicalize the
expression again. */
if (!p->canon_exp)
p->canon_exp = canon_rtx (p->exp);
d.exp = x;
d.mode = full_mode;
if (for_each_rtx (&p->canon_exp, check_dependence, &d))
remove_from_table (p, i);
}
}
}
return;
default:
abort ();
}
}
/* Remove all expressions that refer to register REGNO,
since they are already invalid, and we are about to
mark that register valid again and don't want the old
expressions to reappear as valid. */
static void
remove_invalid_refs (regno)
unsigned int regno;
{
unsigned int i;
struct table_elt *p, *next;
for (i = 0; i < HASH_SIZE; i++)
for (p = table[i]; p; p = next)
{
next = p->next_same_hash;
if (GET_CODE (p->exp) != REG
&& refers_to_regno_p (regno, regno + 1, p->exp, (rtx *) 0))
remove_from_table (p, i);
}
}
/* Likewise for a subreg with subreg_reg REGNO, subreg_byte OFFSET,
and mode MODE. */
static void
remove_invalid_subreg_refs (regno, offset, mode)
unsigned int regno;
unsigned int offset;
enum machine_mode mode;
{
unsigned int i;
struct table_elt *p, *next;
unsigned int end = offset + (GET_MODE_SIZE (mode) - 1);
for (i = 0; i < HASH_SIZE; i++)
for (p = table[i]; p; p = next)
{
rtx exp = p->exp;
next = p->next_same_hash;
if (GET_CODE (exp) != REG
&& (GET_CODE (exp) != SUBREG
|| GET_CODE (SUBREG_REG (exp)) != REG
|| REGNO (SUBREG_REG (exp)) != regno
|| (((SUBREG_BYTE (exp)
+ (GET_MODE_SIZE (GET_MODE (exp)) - 1)) >= offset)
&& SUBREG_BYTE (exp) <= end))
&& refers_to_regno_p (regno, regno + 1, p->exp, (rtx *) 0))
remove_from_table (p, i);
}
}
/* Recompute the hash codes of any valid entries in the hash table that
reference X, if X is a register, or SUBREG_REG (X) if X is a SUBREG.
This is called when we make a jump equivalence. */
static void
rehash_using_reg (x)
rtx x;
{
unsigned int i;
struct table_elt *p, *next;
unsigned hash;
if (GET_CODE (x) == SUBREG)
x = SUBREG_REG (x);
/* If X is not a register or if the register is known not to be in any
valid entries in the table, we have no work to do. */
if (GET_CODE (x) != REG
|| REG_IN_TABLE (REGNO (x)) < 0
|| REG_IN_TABLE (REGNO (x)) != REG_TICK (REGNO (x)))
return;
/* Scan all hash chains looking for valid entries that mention X.
If we find one and it is in the wrong hash chain, move it. We can skip
objects that are registers, since they are handled specially. */
for (i = 0; i < HASH_SIZE; i++)
for (p = table[i]; p; p = next)
{
next = p->next_same_hash;
if (GET_CODE (p->exp) != REG && reg_mentioned_p (x, p->exp)
&& exp_equiv_p (p->exp, p->exp, 1, 0)
&& i != (hash = safe_hash (p->exp, p->mode) & HASH_MASK))
{
if (p->next_same_hash)
p->next_same_hash->prev_same_hash = p->prev_same_hash;
if (p->prev_same_hash)
p->prev_same_hash->next_same_hash = p->next_same_hash;
else
table[i] = p->next_same_hash;
p->next_same_hash = table[hash];
p->prev_same_hash = 0;
if (table[hash])
table[hash]->prev_same_hash = p;
table[hash] = p;
}
}
}
/* Remove from the hash table any expression that is a call-clobbered
register. Also update their TICK values. */
static void
invalidate_for_call ()
{
unsigned int regno, endregno;
unsigned int i;
unsigned hash;
struct table_elt *p, *next;
int in_table = 0;
/* Go through all the hard registers. For each that is clobbered in
a CALL_INSN, remove the register from quantity chains and update
reg_tick if defined. Also see if any of these registers is currently
in the table. */
for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
{
delete_reg_equiv (regno);
if (REG_TICK (regno) >= 0)
{
REG_TICK (regno)++;
SUBREG_TICKED (regno) = -1;
}
in_table |= (TEST_HARD_REG_BIT (hard_regs_in_table, regno) != 0);
}
/* In the case where we have no call-clobbered hard registers in the
table, we are done. Otherwise, scan the table and remove any
entry that overlaps a call-clobbered register. */
if (in_table)
for (hash = 0; hash < HASH_SIZE; hash++)
for (p = table[hash]; p; p = next)
{
next = p->next_same_hash;
if (GET_CODE (p->exp) != REG
|| REGNO (p->exp) >= FIRST_PSEUDO_REGISTER)
continue;
regno = REGNO (p->exp);
endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (p->exp));
for (i = regno; i < endregno; i++)
if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
{
remove_from_table (p, hash);
break;
}
}
}
/* Given an expression X of type CONST,
and ELT which is its table entry (or 0 if it
is not in the hash table),
return an alternate expression for X as a register plus integer.
If none can be found, return 0. */
static rtx
use_related_value (x, elt)
rtx x;
struct table_elt *elt;
{
struct table_elt *relt = 0;
struct table_elt *p, *q;
HOST_WIDE_INT offset;
/* First, is there anything related known?
If we have a table element, we can tell from that.
Otherwise, must look it up. */
if (elt != 0 && elt->related_value != 0)
relt = elt;
else if (elt == 0 && GET_CODE (x) == CONST)
{
rtx subexp = get_related_value (x);
if (subexp != 0)
relt = lookup (subexp,
safe_hash (subexp, GET_MODE (subexp)) & HASH_MASK,
GET_MODE (subexp));
}
if (relt == 0)
return 0;
/* Search all related table entries for one that has an
equivalent register. */
p = relt;
while (1)
{
/* This loop is strange in that it is executed in two different cases.
The first is when X is already in the table. Then it is searching
the RELATED_VALUE list of X's class (RELT). The second case is when
X is not in the table. Then RELT points to a class for the related
value.
Ensure that, whatever case we are in, that we ignore classes that have
the same value as X. */
if (rtx_equal_p (x, p->exp))
q = 0;
else
for (q = p->first_same_value; q; q = q->next_same_value)
if (GET_CODE (q->exp) == REG)
break;
if (q)
break;
p = p->related_value;
/* We went all the way around, so there is nothing to be found.
Alternatively, perhaps RELT was in the table for some other reason
and it has no related values recorded. */
if (p == relt || p == 0)
break;
}
if (q == 0)
return 0;
offset = (get_integer_term (x) - get_integer_term (p->exp));
/* Note: OFFSET may be 0 if P->xexp and X are related by commutativity. */
return plus_constant (q->exp, offset);
}
/* Hash a string. Just add its bytes up. */
static inline unsigned
canon_hash_string (ps)
const char *ps;
{
unsigned hash = 0;
const unsigned char *p = (const unsigned char *) ps;
if (p)
while (*p)
hash += *p++;
return hash;
}
/* Hash an rtx. We are careful to make sure the value is never negative.
Equivalent registers hash identically.
MODE is used in hashing for CONST_INTs only;
otherwise the mode of X is used.
Store 1 in do_not_record if any subexpression is volatile.
Store 1 in hash_arg_in_memory if X contains a MEM rtx
which does not have the RTX_UNCHANGING_P bit set.
Note that cse_insn knows that the hash code of a MEM expression
is just (int) MEM plus the hash code of the address. */
static unsigned
canon_hash (x, mode)
rtx x;
enum machine_mode mode;
{
int i, j;
unsigned hash = 0;
enum rtx_code code;
const char *fmt;
/* repeat is used to turn tail-recursion into iteration. */
repeat:
if (x == 0)
return hash;
code = GET_CODE (x);
switch (code)
{
case REG:
{
unsigned int regno = REGNO (x);
bool record;
/* On some machines, we can't record any non-fixed hard register,
because extending its life will cause reload problems. We
consider ap, fp, sp, gp to be fixed for this purpose.
We also consider CCmode registers to be fixed for this purpose;
failure to do so leads to failure to simplify 0<100 type of
conditionals.
On all machines, we can't record any global registers.
Nor should we record any register that is in a small
class, as defined by CLASS_LIKELY_SPILLED_P. */
if (regno >= FIRST_PSEUDO_REGISTER)
record = true;
else if (x == frame_pointer_rtx
|| x == hard_frame_pointer_rtx
|| x == arg_pointer_rtx
|| x == stack_pointer_rtx
|| x == pic_offset_table_rtx)
record = true;
else if (global_regs[regno])
record = false;
else if (fixed_regs[regno])
record = true;
else if (GET_MODE_CLASS (GET_MODE (x)) == MODE_CC)
record = true;
else if (SMALL_REGISTER_CLASSES)
record = false;
else if (CLASS_LIKELY_SPILLED_P (REGNO_REG_CLASS (regno)))
record = false;
else
record = true;
if (!record)
{
do_not_record = 1;
return 0;
}
hash += ((unsigned) REG << 7) + (unsigned) REG_QTY (regno);
return hash;
}
/* We handle SUBREG of a REG specially because the underlying
reg changes its hash value with every value change; we don't
want to have to forget unrelated subregs when one subreg changes. */
case SUBREG:
{
if (GET_CODE (SUBREG_REG (x)) == REG)
{
hash += (((unsigned) SUBREG << 7)
+ REGNO (SUBREG_REG (x))
+ (SUBREG_BYTE (x) / UNITS_PER_WORD));
return hash;
}
break;
}
case CONST_INT:
{
unsigned HOST_WIDE_INT tem = INTVAL (x);
hash += ((unsigned) CONST_INT << 7) + (unsigned) mode + tem;
return hash;
}
case CONST_DOUBLE:
/* This is like the general case, except that it only counts
the integers representing the constant. */
hash += (unsigned) code + (unsigned) GET_MODE (x);
if (GET_MODE (x) != VOIDmode)
hash += real_hash (CONST_DOUBLE_REAL_VALUE (x));
else
hash += ((unsigned) CONST_DOUBLE_LOW (x)
+ (unsigned) CONST_DOUBLE_HIGH (x));
return hash;
case CONST_VECTOR:
{
int units;
rtx elt;
units = CONST_VECTOR_NUNITS (x);
for (i = 0; i < units; ++i)
{
elt = CONST_VECTOR_ELT (x, i);
hash += canon_hash (elt, GET_MODE (elt));
}
return hash;
}
/* Assume there is only one rtx object for any given label. */
case LABEL_REF:
hash += ((unsigned) LABEL_REF << 7) + (unsigned long) XEXP (x, 0);
return hash;
case SYMBOL_REF:
hash += ((unsigned) SYMBOL_REF << 7) + (unsigned long) XSTR (x, 0);
return hash;
case MEM:
/* We don't record if marked volatile or if BLKmode since we don't
know the size of the move. */
if (MEM_VOLATILE_P (x) || GET_MODE (x) == BLKmode)
{
do_not_record = 1;
return 0;
}
if (! RTX_UNCHANGING_P (x) || FIXED_BASE_PLUS_P (XEXP (x, 0)))
{
hash_arg_in_memory = 1;
}
/* Now that we have already found this special case,
might as well speed it up as much as possible. */
hash += (unsigned) MEM;
x = XEXP (x, 0);
goto repeat;
case USE:
/* A USE that mentions non-volatile memory needs special
handling since the MEM may be BLKmode which normally
prevents an entry from being made. Pure calls are
marked by a USE which mentions BLKmode memory. */
if (GET_CODE (XEXP (x, 0)) == MEM
&& ! MEM_VOLATILE_P (XEXP (x, 0)))
{
hash += (unsigned) USE;
x = XEXP (x, 0);
if (! RTX_UNCHANGING_P (x) || FIXED_BASE_PLUS_P (XEXP (x, 0)))
hash_arg_in_memory = 1;
/* Now that we have already found this special case,
might as well speed it up as much as possible. */
hash += (unsigned) MEM;
x = XEXP (x, 0);
goto repeat;
}
break;
case PRE_DEC:
case PRE_INC:
case POST_DEC:
case POST_INC:
case PRE_MODIFY:
case POST_MODIFY:
case PC:
case CC0:
case CALL:
case UNSPEC_VOLATILE:
do_not_record = 1;
return 0;
case ASM_OPERANDS:
if (MEM_VOLATILE_P (x))
{
do_not_record = 1;
return 0;
}
else
{
/* We don't want to take the filename and line into account. */
hash += (unsigned) code + (unsigned) GET_MODE (x)
+ canon_hash_string (ASM_OPERANDS_TEMPLATE (x))
+ canon_hash_string (ASM_OPERANDS_OUTPUT_CONSTRAINT (x))
+ (unsigned) ASM_OPERANDS_OUTPUT_IDX (x);
if (ASM_OPERANDS_INPUT_LENGTH (x))
{
for (i = 1; i < ASM_OPERANDS_INPUT_LENGTH (x); i++)
{
hash += (canon_hash (ASM_OPERANDS_INPUT (x, i),
GET_MODE (ASM_OPERANDS_INPUT (x, i)))
+ canon_hash_string (ASM_OPERANDS_INPUT_CONSTRAINT
(x, i)));
}
hash += canon_hash_string (ASM_OPERANDS_INPUT_CONSTRAINT (x, 0));
x = ASM_OPERANDS_INPUT (x, 0);
mode = GET_MODE (x);
goto repeat;
}
return hash;
}
break;
default:
break;
}
i = GET_RTX_LENGTH (code) - 1;
hash += (unsigned) code + (unsigned) GET_MODE (x);
fmt = GET_RTX_FORMAT (code);
for (; i >= 0; i--)
{
if (fmt[i] == 'e')
{
rtx tem = XEXP (x, i);
/* If we are about to do the last recursive call
needed at this level, change it into iteration.
This function is called enough to be worth it. */
if (i == 0)
{
x = tem;
goto repeat;
}
hash += canon_hash (tem, 0);
}
else if (fmt[i] == 'E')
for (j = 0; j < XVECLEN (x, i); j++)
hash += canon_hash (XVECEXP (x, i, j), 0);
else if (fmt[i] == 's')
hash += canon_hash_string (XSTR (x, i));
else if (fmt[i] == 'i')
{
unsigned tem = XINT (x, i);
hash += tem;
}
else if (fmt[i] == '0' || fmt[i] == 't')
/* Unused. */
;
else
abort ();
}
return hash;
}
/* Like canon_hash but with no side effects. */
static unsigned
safe_hash (x, mode)
rtx x;
enum machine_mode mode;
{
int save_do_not_record = do_not_record;
int save_hash_arg_in_memory = hash_arg_in_memory;
unsigned hash = canon_hash (x, mode);
hash_arg_in_memory = save_hash_arg_in_memory;
do_not_record = save_do_not_record;
return hash;
}
/* Return 1 iff X and Y would canonicalize into the same thing,
without actually constructing the canonicalization of either one.
If VALIDATE is nonzero,
we assume X is an expression being processed from the rtl
and Y was found in the hash table. We check register refs
in Y for being marked as valid.
If EQUAL_VALUES is nonzero, we allow a register to match a constant value
that is known to be in the register. Ordinarily, we don't allow them
to match, because letting them match would cause unpredictable results
in all the places that search a hash table chain for an equivalent
for a given value. A possible equivalent that has different structure
has its hash code computed from different data. Whether the hash code
is the same as that of the given value is pure luck. */
static int
exp_equiv_p (x, y, validate, equal_values)
rtx x, y;
int validate;
int equal_values;
{
int i, j;
enum rtx_code code;
const char *fmt;
/* Note: it is incorrect to assume an expression is equivalent to itself
if VALIDATE is nonzero. */
if (x == y && !validate)
return 1;
if (x == 0 || y == 0)
return x == y;
code = GET_CODE (x);
if (code != GET_CODE (y))
{
if (!equal_values)
return 0;
/* If X is a constant and Y is a register or vice versa, they may be
equivalent. We only have to validate if Y is a register. */
if (CONSTANT_P (x) && GET_CODE (y) == REG
&& REGNO_QTY_VALID_P (REGNO (y)))
{
int y_q = REG_QTY (REGNO (y));
struct qty_table_elem *y_ent = &qty_table[y_q];
if (GET_MODE (y) == y_ent->mode
&& rtx_equal_p (x, y_ent->const_rtx)
&& (! validate || REG_IN_TABLE (REGNO (y)) == REG_TICK (REGNO (y))))
return 1;
}
if (CONSTANT_P (y) && code == REG
&& REGNO_QTY_VALID_P (REGNO (x)))
{
int x_q = REG_QTY (REGNO (x));
struct qty_table_elem *x_ent = &qty_table[x_q];
if (GET_MODE (x) == x_ent->mode
&& rtx_equal_p (y, x_ent->const_rtx))
return 1;
}
return 0;
}
/* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
if (GET_MODE (x) != GET_MODE (y))
return 0;
switch (code)
{
case PC:
case CC0:
case CONST_INT:
return x == y;
case LABEL_REF:
return XEXP (x, 0) == XEXP (y, 0);
case SYMBOL_REF:
return XSTR (x, 0) == XSTR (y, 0);
case REG:
{
unsigned int regno = REGNO (y);
unsigned int endregno
= regno + (regno >= FIRST_PSEUDO_REGISTER ? 1
: HARD_REGNO_NREGS (regno, GET_MODE (y)));
unsigned int i;
/* If the quantities are not the same, the expressions are not
equivalent. If there are and we are not to validate, they
are equivalent. Otherwise, ensure all regs are up-to-date. */
if (REG_QTY (REGNO (x)) != REG_QTY (regno))
return 0;
if (! validate)
return 1;
for (i = regno; i < endregno; i++)
if (REG_IN_TABLE (i) != REG_TICK (i))
return 0;
return 1;
}
/* For commutative operations, check both orders. */
case PLUS:
case MULT:
case AND:
case IOR:
case XOR:
case NE:
case EQ:
return ((exp_equiv_p (XEXP (x, 0), XEXP (y, 0), validate, equal_values)
&& exp_equiv_p (XEXP (x, 1), XEXP (y, 1),
validate, equal_values))
|| (exp_equiv_p (XEXP (x, 0), XEXP (y, 1),
validate, equal_values)
&& exp_equiv_p (XEXP (x, 1), XEXP (y, 0),
validate, equal_values)));
case ASM_OPERANDS:
/* We don't use the generic code below because we want to
disregard filename and line numbers. */
/* A volatile asm isn't equivalent to any other. */
if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
return 0;
if (GET_MODE (x) != GET_MODE (y)
|| strcmp (ASM_OPERANDS_TEMPLATE (x), ASM_OPERANDS_TEMPLATE (y))
|| strcmp (ASM_OPERANDS_OUTPUT_CONSTRAINT (x),
ASM_OPERANDS_OUTPUT_CONSTRAINT (y))
|| ASM_OPERANDS_OUTPUT_IDX (x) != ASM_OPERANDS_OUTPUT_IDX (y)
|| ASM_OPERANDS_INPUT_LENGTH (x) != ASM_OPERANDS_INPUT_LENGTH (y))
return 0;
if (ASM_OPERANDS_INPUT_LENGTH (x))
{
for (i = ASM_OPERANDS_INPUT_LENGTH (x) - 1; i >= 0; i--)
if (! exp_equiv_p (ASM_OPERANDS_INPUT (x, i),
ASM_OPERANDS_INPUT (y, i),
validate, equal_values)
|| strcmp (ASM_OPERANDS_INPUT_CONSTRAINT (x, i),
ASM_OPERANDS_INPUT_CONSTRAINT (y, i)))
return 0;
}
return 1;
default:
break;
}
/* Compare the elements. If any pair of corresponding elements
fail to match, return 0 for the whole things. */
fmt = GET_RTX_FORMAT (code);
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
{
switch (fmt[i])
{
case 'e':
if (! exp_equiv_p (XEXP (x, i), XEXP (y, i), validate, equal_values))
return 0;
break;
case 'E':
if (XVECLEN (x, i) != XVECLEN (y, i))
return 0;
for (j = 0; j < XVECLEN (x, i); j++)
if (! exp_equiv_p (XVECEXP (x, i, j), XVECEXP (y, i, j),
validate, equal_values))
return 0;
break;
case 's':
if (strcmp (XSTR (x, i), XSTR (y, i)))
return 0;
break;
case 'i':
if (XINT (x, i) != XINT (y, i))
return 0;
break;
case 'w':
if (XWINT (x, i) != XWINT (y, i))
return 0;
break;
case '0':
case 't':
break;
default:
abort ();
}
}
return 1;
}
/* Return 1 if X has a value that can vary even between two
executions of the program. 0 means X can be compared reliably
against certain constants or near-constants. */
static int
cse_rtx_varies_p (x, from_alias)
rtx x;
int from_alias;
{
/* We need not check for X and the equivalence class being of the same
mode because if X is equivalent to a constant in some mode, it
doesn't vary in any mode. */
if (GET_CODE (x) == REG
&& REGNO_QTY_VALID_P (REGNO (x)))
{
int x_q = REG_QTY (REGNO (x));
struct qty_table_elem *x_ent = &qty_table[x_q];
if (GET_MODE (x) == x_ent->mode
&& x_ent->const_rtx != NULL_RTX)
return 0;
}
if (GET_CODE (x) == PLUS
&& GET_CODE (XEXP (x, 1)) == CONST_INT
&& GET_CODE (XEXP (x, 0)) == REG
&& REGNO_QTY_VALID_P (REGNO (XEXP (x, 0))))
{
int x0_q = REG_QTY (REGNO (XEXP (x, 0)));
struct qty_table_elem *x0_ent = &qty_table[x0_q];
if ((GET_MODE (XEXP (x, 0)) == x0_ent->mode)
&& x0_ent->const_rtx != NULL_RTX)
return 0;
}
/* This can happen as the result of virtual register instantiation, if
the initial constant is too large to be a valid address. This gives
us a three instruction sequence, load large offset into a register,
load fp minus a constant into a register, then a MEM which is the
sum of the two `constant' registers. */
if (GET_CODE (x) == PLUS
&& GET_CODE (XEXP (x, 0)) == REG
&& GET_CODE (XEXP (x, 1)) == REG
&& REGNO_QTY_VALID_P (REGNO (XEXP (x, 0)))
&& REGNO_QTY_VALID_P (REGNO (XEXP (x, 1))))
{
int x0_q = REG_QTY (REGNO (XEXP (x, 0)));
int x1_q = REG_QTY (REGNO (XEXP (x, 1)));
struct qty_table_elem *x0_ent = &qty_table[x0_q];
struct qty_table_elem *x1_ent = &qty_table[x1_q];
if ((GET_MODE (XEXP (x, 0)) == x0_ent->mode)
&& x0_ent->const_rtx != NULL_RTX
&& (GET_MODE (XEXP (x, 1)) == x1_ent->mode)
&& x1_ent->const_rtx != NULL_RTX)
return 0;
}
return rtx_varies_p (x, from_alias);
}
/* Canonicalize an expression:
replace each register reference inside it
with the "oldest" equivalent register.
If INSN is nonzero and we are replacing a pseudo with a hard register
or vice versa, validate_change is used to ensure that INSN remains valid
after we make our substitution. The calls are made with IN_GROUP nonzero
so apply_change_group must be called upon the outermost return from this
function (unless INSN is zero). The result of apply_change_group can
generally be discarded since the changes we are making are optional. */
static rtx
canon_reg (x, insn)
rtx x;
rtx insn;
{
int i;
enum rtx_code code;
const char *fmt;
if (x == 0)
return x;
code = GET_CODE (x);
switch (code)
{
case PC:
case CC0:
case CONST:
case CONST_INT:
case CONST_DOUBLE:
case CONST_VECTOR:
case SYMBOL_REF:
case LABEL_REF:
case ADDR_VEC:
case ADDR_DIFF_VEC:
return x;
case REG:
{
int first;
int q;
struct qty_table_elem *ent;
/* Never replace a hard reg, because hard regs can appear
in more than one machine mode, and we must preserve the mode
of each occurrence. Also, some hard regs appear in
MEMs that are shared and mustn't be altered. Don't try to
replace any reg that maps to a reg of class NO_REGS. */
if (REGNO (x) < FIRST_PSEUDO_REGISTER
|| ! REGNO_QTY_VALID_P (REGNO (x)))
return x;
q = REG_QTY (REGNO (x));
ent = &qty_table[q];
first = ent->first_reg;
return (first >= FIRST_PSEUDO_REGISTER ? regno_reg_rtx[first]
: REGNO_REG_CLASS (first) == NO_REGS ? x
: gen_rtx_REG (ent->mode, first));
}
default:
break;
}
fmt = GET_RTX_FORMAT (code);
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
{
int j;
if (fmt[i] == 'e')
{
rtx new = canon_reg (XEXP (x, i), insn);
int insn_code;
/* If replacing pseudo with hard reg or vice versa, ensure the
insn remains valid. Likewise if the insn has MATCH_DUPs. */
if (insn != 0 && new != 0
&& GET_CODE (new) == REG && GET_CODE (XEXP (x, i)) == REG
&& (((REGNO (new) < FIRST_PSEUDO_REGISTER)
!= (REGNO (XEXP (x, i)) < FIRST_PSEUDO_REGISTER))
|| (insn_code = recog_memoized (insn)) < 0
|| insn_data[insn_code].n_dups > 0))
validate_change (insn, &XEXP (x, i), new, 1);
else
XEXP (x, i) = new;
}
else if (fmt[i] == 'E')
for (j = 0; j < XVECLEN (x, i); j++)
XVECEXP (x, i, j) = canon_reg (XVECEXP (x, i, j), insn);
}
return x;
}
/* LOC is a location within INSN that is an operand address (the contents of
a MEM). Find the best equivalent address to use that is valid for this
insn.
On most CISC machines, complicated address modes are costly, and rtx_cost
is a good approximation for that cost. However, most RISC machines have
only a few (usually only one) memory reference formats. If an address is
valid at all, it is often just as cheap as any other address. Hence, for
RISC machines, we use the configuration macro `ADDRESS_COST' to compare the
costs of various addresses. For two addresses of equal cost, choose the one
with the highest `rtx_cost' value as that has the potential of eliminating
the most insns. For equal costs, we choose the first in the equivalence
class. Note that we ignore the fact that pseudo registers are cheaper
than hard registers here because we would also prefer the pseudo registers.
*/
static void
find_best_addr (insn, loc, mode)
rtx insn;
rtx *loc;
enum machine_mode mode;
{
struct table_elt *elt;
rtx addr = *loc;
#ifdef ADDRESS_COST
struct table_elt *p;
int found_better = 1;
#endif
int save_do_not_record = do_not_record;
int save_hash_arg_in_memory = hash_arg_in_memory;
int addr_volatile;
int regno;
unsigned hash;
/* Do not try to replace constant addresses or addresses of local and
argument slots. These MEM expressions are made only once and inserted
in many instructions, as well as being used to control symbol table
output. It is not safe to clobber them.
There are some uncommon cases where the address is already in a register
for some reason, but we cannot take advantage of that because we have
no easy way to unshare the MEM. In addition, looking up all stack
addresses is costly. */
if ((GET_CODE (addr) == PLUS
&& GET_CODE (XEXP (addr, 0)) == REG
&& GET_CODE (XEXP (addr, 1)) == CONST_INT
&& (regno = REGNO (XEXP (addr, 0)),
regno == FRAME_POINTER_REGNUM || regno == HARD_FRAME_POINTER_REGNUM
|| regno == ARG_POINTER_REGNUM))
|| (GET_CODE (addr) == REG
&& (regno = REGNO (addr), regno == FRAME_POINTER_REGNUM
|| regno == HARD_FRAME_POINTER_REGNUM
|| regno == ARG_POINTER_REGNUM))
|| GET_CODE (addr) == ADDRESSOF
|| CONSTANT_ADDRESS_P (addr))
return;
/* If this address is not simply a register, try to fold it. This will
sometimes simplify the expression. Many simplifications
will not be valid, but some, usually applying the associative rule, will
be valid and produce better code. */
if (GET_CODE (addr) != REG)
{
rtx folded = fold_rtx (copy_rtx (addr), NULL_RTX);
int addr_folded_cost = address_cost (folded, mode);
int addr_cost = address_cost (addr, mode);
if ((addr_folded_cost < addr_cost
|| (addr_folded_cost == addr_cost
/* ??? The rtx_cost comparison is left over from an older
version of this code. It is probably no longer helpful. */
&& (rtx_cost (folded, MEM) > rtx_cost (addr, MEM)
|| approx_reg_cost (folded) < approx_reg_cost (addr))))
&& validate_change (insn, loc, folded, 0))
addr = folded;
}
/* If this address is not in the hash table, we can't look for equivalences
of the whole address. Also, ignore if volatile. */
do_not_record = 0;
hash = HASH (addr, Pmode);
addr_volatile = do_not_record;
do_not_record = save_do_not_record;
hash_arg_in_memory = save_hash_arg_in_memory;
if (addr_volatile)
return;
elt = lookup (addr, hash, Pmode);
#ifndef ADDRESS_COST
if (elt)
{
int our_cost = elt->cost;
/* Find the lowest cost below ours that works. */
for (elt = elt->first_same_value; elt; elt = elt->next_same_value)
if (elt->cost < our_cost
&& (GET_CODE (elt->exp) == REG
|| exp_equiv_p (elt->exp, elt->exp, 1, 0))
&& validate_change (insn, loc,
canon_reg (copy_rtx (elt->exp), NULL_RTX), 0))
return;
}
#else
if (elt)
{
/* We need to find the best (under the criteria documented above) entry
in the class that is valid. We use the `flag' field to indicate
choices that were invalid and iterate until we can't find a better
one that hasn't already been tried. */
for (p = elt->first_same_value; p; p = p->next_same_value)
p->flag = 0;
while (found_better)
{
int best_addr_cost = address_cost (*loc, mode);
int best_rtx_cost = (elt->cost + 1) >> 1;
int exp_cost;
struct table_elt *best_elt = elt;
found_better = 0;
for (p = elt->first_same_value; p; p = p->next_same_value)
if (! p->flag)
{
if ((GET_CODE (p->exp) == REG
|| exp_equiv_p (p->exp, p->exp, 1, 0))
&& ((exp_cost = address_cost (p->exp, mode)) < best_addr_cost
|| (exp_cost == best_addr_cost
&& ((p->cost + 1) >> 1) > best_rtx_cost)))
{
found_better = 1;
best_addr_cost = exp_cost;
best_rtx_cost = (p->cost + 1) >> 1;
best_elt = p;
}
}
if (found_better)
{
if (validate_change (insn, loc,
canon_reg (copy_rtx (best_elt->exp),
NULL_RTX), 0))
return;
else
best_elt->flag = 1;
}
}
}
/* If the address is a binary operation with the first operand a register
and the second a constant, do the same as above, but looking for
equivalences of the register. Then try to simplify before checking for
the best address to use. This catches a few cases: First is when we
have REG+const and the register is another REG+const. We can often merge
the constants and eliminate one insn and one register. It may also be
that a machine has a cheap REG+REG+const. Finally, this improves the
code on the Alpha for unaligned byte stores. */
if (flag_expensive_optimizations
&& (GET_RTX_CLASS (GET_CODE (*loc)) == '2'
|| GET_RTX_CLASS (GET_CODE (*loc)) == 'c')
&& GET_CODE (XEXP (*loc, 0)) == REG
&& GET_CODE (XEXP (*loc, 1)) == CONST_INT)
{
rtx c = XEXP (*loc, 1);
do_not_record = 0;
hash = HASH (XEXP (*loc, 0), Pmode);
do_not_record = save_do_not_record;
hash_arg_in_memory = save_hash_arg_in_memory;
elt = lookup (XEXP (*loc, 0), hash, Pmode);
if (elt == 0)
return;
/* We need to find the best (under the criteria documented above) entry
in the class that is valid. We use the `flag' field to indicate
choices that were invalid and iterate until we can't find a better
one that hasn't already been tried. */
for (p = elt->first_same_value; p; p = p->next_same_value)
p->flag = 0;
while (found_better)
{
int best_addr_cost = address_cost (*loc, mode);
int best_rtx_cost = (COST (*loc) + 1) >> 1;
struct table_elt *best_elt = elt;
rtx best_rtx = *loc;
int count;
/* This is at worst case an O(n^2) algorithm, so limit our search
to the first 32 elements on the list. This avoids trouble
compiling code with very long basic blocks that can easily
call simplify_gen_binary so many times that we run out of
memory. */
found_better = 0;
for (p = elt->first_same_value, count = 0;
p && count < 32;
p = p->next_same_value, count++)
if (! p->flag
&& (GET_CODE (p->exp) == REG
|| exp_equiv_p (p->exp, p->exp, 1, 0)))
{
rtx new = simplify_gen_binary (GET_CODE (*loc), Pmode,
p->exp, c);
int new_cost;
new_cost = address_cost (new, mode);
if (new_cost < best_addr_cost
|| (new_cost == best_addr_cost
&& (COST (new) + 1) >> 1 > best_rtx_cost))
{
found_better = 1;
best_addr_cost = new_cost;
best_rtx_cost = (COST (new) + 1) >> 1;
best_elt = p;
best_rtx = new;
}
}
if (found_better)
{
if (validate_change (insn, loc,
canon_reg (copy_rtx (best_rtx),
NULL_RTX), 0))
return;
else
best_elt->flag = 1;
}
}
}
#endif
}
/* Given an operation (CODE, *PARG1, *PARG2), where code is a comparison
operation (EQ, NE, GT, etc.), follow it back through the hash table and
what values are being compared.
*PARG1 and *PARG2 are updated to contain the rtx representing the values
actually being compared. For example, if *PARG1 was (cc0) and *PARG2
was (const_int 0), *PARG1 and *PARG2 will be set to the objects that were
compared to produce cc0.
The return value is the comparison operator and is either the code of
A or the code corresponding to the inverse of the comparison. */
static enum rtx_code
find_comparison_args (code, parg1, parg2, pmode1, pmode2)
enum rtx_code code;
rtx *parg1, *parg2;
enum machine_mode *pmode1, *pmode2;
{
rtx arg1, arg2;
arg1 = *parg1, arg2 = *parg2;
/* If ARG2 is const0_rtx, see what ARG1 is equivalent to. */
while (arg2 == CONST0_RTX (GET_MODE (arg1)))
{
/* Set nonzero when we find something of interest. */
rtx x = 0;
int reverse_code = 0;
struct table_elt *p = 0;
/* If arg1 is a COMPARE, extract the comparison arguments from it.
On machines with CC0, this is the only case that can occur, since
fold_rtx will return the COMPARE or item being compared with zero
when given CC0. */
if (GET_CODE (arg1) == COMPARE && arg2 == const0_rtx)
x = arg1;
/* If ARG1 is a comparison operator and CODE is testing for
STORE_FLAG_VALUE, get the inner arguments. */
else if (GET_RTX_CLASS (GET_CODE (arg1)) == '<')
{
#ifdef FLOAT_STORE_FLAG_VALUE
REAL_VALUE_TYPE fsfv;
#endif
if (code == NE
|| (GET_MODE_CLASS (GET_MODE (arg1)) == MODE_INT
&& code == LT && STORE_FLAG_VALUE == -1)
#ifdef FLOAT_STORE_FLAG_VALUE
|| (GET_MODE_CLASS (GET_MODE (arg1)) == MODE_FLOAT
&& (fsfv = FLOAT_STORE_FLAG_VALUE (GET_MODE (arg1)),
REAL_VALUE_NEGATIVE (fsfv)))
#endif
)
x =