2688 lines
80 KiB
C
2688 lines
80 KiB
C
/* Straight-line strength reduction.
|
||
Copyright (C) 2012 Free Software Foundation, Inc.
|
||
Contributed by Bill Schmidt, IBM <wschmidt@linux.ibm.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/>. */
|
||
|
||
/* There are many algorithms for performing strength reduction on
|
||
loops. This is not one of them. IVOPTS handles strength reduction
|
||
of induction variables just fine. This pass is intended to pick
|
||
up the crumbs it leaves behind, by considering opportunities for
|
||
strength reduction along dominator paths.
|
||
|
||
Strength reduction will be implemented in four stages, gradually
|
||
adding more complex candidates:
|
||
|
||
1) Explicit multiplies, known constant multipliers, no
|
||
conditional increments. (complete)
|
||
2) Explicit multiplies, unknown constant multipliers,
|
||
no conditional increments. (complete)
|
||
3) Implicit multiplies in addressing expressions. (complete)
|
||
4) Explicit multiplies, conditional increments. (pending)
|
||
|
||
It would also be possible to apply strength reduction to divisions
|
||
and modulos, but such opportunities are relatively uncommon.
|
||
|
||
Strength reduction is also currently restricted to integer operations.
|
||
If desired, it could be extended to floating-point operations under
|
||
control of something like -funsafe-math-optimizations. */
|
||
|
||
#include "config.h"
|
||
#include "system.h"
|
||
#include "coretypes.h"
|
||
#include "tree.h"
|
||
#include "gimple.h"
|
||
#include "basic-block.h"
|
||
#include "tree-pass.h"
|
||
#include "cfgloop.h"
|
||
#include "gimple-pretty-print.h"
|
||
#include "tree-flow.h"
|
||
#include "domwalk.h"
|
||
#include "pointer-set.h"
|
||
#include "expmed.h"
|
||
|
||
/* Information about a strength reduction candidate. Each statement
|
||
in the candidate table represents an expression of one of the
|
||
following forms (the special case of CAND_REF will be described
|
||
later):
|
||
|
||
(CAND_MULT) S1: X = (B + i) * S
|
||
(CAND_ADD) S1: X = B + (i * S)
|
||
|
||
Here X and B are SSA names, i is an integer constant, and S is
|
||
either an SSA name or a constant. We call B the "base," i the
|
||
"index", and S the "stride."
|
||
|
||
Any statement S0 that dominates S1 and is of the form:
|
||
|
||
(CAND_MULT) S0: Y = (B + i') * S
|
||
(CAND_ADD) S0: Y = B + (i' * S)
|
||
|
||
is called a "basis" for S1. In both cases, S1 may be replaced by
|
||
|
||
S1': X = Y + (i - i') * S,
|
||
|
||
where (i - i') * S is folded to the extent possible.
|
||
|
||
All gimple statements are visited in dominator order, and each
|
||
statement that may contribute to one of the forms of S1 above is
|
||
given at least one entry in the candidate table. Such statements
|
||
include addition, pointer addition, subtraction, multiplication,
|
||
negation, copies, and nontrivial type casts. If a statement may
|
||
represent more than one expression of the forms of S1 above,
|
||
multiple "interpretations" are stored in the table and chained
|
||
together. Examples:
|
||
|
||
* An add of two SSA names may treat either operand as the base.
|
||
* A multiply of two SSA names, likewise.
|
||
* A copy or cast may be thought of as either a CAND_MULT with
|
||
i = 0 and S = 1, or as a CAND_ADD with i = 0 or S = 0.
|
||
|
||
Candidate records are allocated from an obstack. They are addressed
|
||
both from a hash table keyed on S1, and from a vector of candidate
|
||
pointers arranged in predominator order.
|
||
|
||
Opportunity note
|
||
----------------
|
||
Currently we don't recognize:
|
||
|
||
S0: Y = (S * i') - B
|
||
S1: X = (S * i) - B
|
||
|
||
as a strength reduction opportunity, even though this S1 would
|
||
also be replaceable by the S1' above. This can be added if it
|
||
comes up in practice.
|
||
|
||
Strength reduction in addressing
|
||
--------------------------------
|
||
There is another kind of candidate known as CAND_REF. A CAND_REF
|
||
describes a statement containing a memory reference having
|
||
complex addressing that might benefit from strength reduction.
|
||
Specifically, we are interested in references for which
|
||
get_inner_reference returns a base address, offset, and bitpos as
|
||
follows:
|
||
|
||
base: MEM_REF (T1, C1)
|
||
offset: MULT_EXPR (PLUS_EXPR (T2, C2), C3)
|
||
bitpos: C4 * BITS_PER_UNIT
|
||
|
||
Here T1 and T2 are arbitrary trees, and C1, C2, C3, C4 are
|
||
arbitrary integer constants. Note that C2 may be zero, in which
|
||
case the offset will be MULT_EXPR (T2, C3).
|
||
|
||
When this pattern is recognized, the original memory reference
|
||
can be replaced with:
|
||
|
||
MEM_REF (POINTER_PLUS_EXPR (T1, MULT_EXPR (T2, C3)),
|
||
C1 + (C2 * C3) + C4)
|
||
|
||
which distributes the multiply to allow constant folding. When
|
||
two or more addressing expressions can be represented by MEM_REFs
|
||
of this form, differing only in the constants C1, C2, and C4,
|
||
making this substitution produces more efficient addressing during
|
||
the RTL phases. When there are not at least two expressions with
|
||
the same values of T1, T2, and C3, there is nothing to be gained
|
||
by the replacement.
|
||
|
||
Strength reduction of CAND_REFs uses the same infrastructure as
|
||
that used by CAND_MULTs and CAND_ADDs. We record T1 in the base (B)
|
||
field, MULT_EXPR (T2, C3) in the stride (S) field, and
|
||
C1 + (C2 * C3) + C4 in the index (i) field. A basis for a CAND_REF
|
||
is thus another CAND_REF with the same B and S values. When at
|
||
least two CAND_REFs are chained together using the basis relation,
|
||
each of them is replaced as above, resulting in improved code
|
||
generation for addressing. */
|
||
|
||
|
||
/* Index into the candidate vector, offset by 1. VECs are zero-based,
|
||
while cand_idx's are one-based, with zero indicating null. */
|
||
typedef unsigned cand_idx;
|
||
|
||
/* The kind of candidate. */
|
||
enum cand_kind
|
||
{
|
||
CAND_MULT,
|
||
CAND_ADD,
|
||
CAND_REF
|
||
};
|
||
|
||
struct slsr_cand_d
|
||
{
|
||
/* The candidate statement S1. */
|
||
gimple cand_stmt;
|
||
|
||
/* The base expression B: often an SSA name, but not always. */
|
||
tree base_expr;
|
||
|
||
/* The stride S. */
|
||
tree stride;
|
||
|
||
/* The index constant i. */
|
||
double_int index;
|
||
|
||
/* The type of the candidate. This is normally the type of base_expr,
|
||
but casts may have occurred when combining feeding instructions.
|
||
A candidate can only be a basis for candidates of the same final type.
|
||
(For CAND_REFs, this is the type to be used for operand 1 of the
|
||
replacement MEM_REF.) */
|
||
tree cand_type;
|
||
|
||
/* The kind of candidate (CAND_MULT, etc.). */
|
||
enum cand_kind kind;
|
||
|
||
/* Index of this candidate in the candidate vector. */
|
||
cand_idx cand_num;
|
||
|
||
/* Index of the next candidate record for the same statement.
|
||
A statement may be useful in more than one way (e.g., due to
|
||
commutativity). So we can have multiple "interpretations"
|
||
of a statement. */
|
||
cand_idx next_interp;
|
||
|
||
/* Index of the basis statement S0, if any, in the candidate vector. */
|
||
cand_idx basis;
|
||
|
||
/* First candidate for which this candidate is a basis, if one exists. */
|
||
cand_idx dependent;
|
||
|
||
/* Next candidate having the same basis as this one. */
|
||
cand_idx sibling;
|
||
|
||
/* If this is a conditional candidate, the defining PHI statement
|
||
for the base SSA name B. For future use; always NULL for now. */
|
||
gimple def_phi;
|
||
|
||
/* Savings that can be expected from eliminating dead code if this
|
||
candidate is replaced. */
|
||
int dead_savings;
|
||
};
|
||
|
||
typedef struct slsr_cand_d slsr_cand, *slsr_cand_t;
|
||
typedef const struct slsr_cand_d *const_slsr_cand_t;
|
||
|
||
/* Pointers to candidates are chained together as part of a mapping
|
||
from base expressions to the candidates that use them. */
|
||
|
||
struct cand_chain_d
|
||
{
|
||
/* Base expression for the chain of candidates: often, but not
|
||
always, an SSA name. */
|
||
tree base_expr;
|
||
|
||
/* Pointer to a candidate. */
|
||
slsr_cand_t cand;
|
||
|
||
/* Chain pointer. */
|
||
struct cand_chain_d *next;
|
||
|
||
};
|
||
|
||
typedef struct cand_chain_d cand_chain, *cand_chain_t;
|
||
typedef const struct cand_chain_d *const_cand_chain_t;
|
||
|
||
/* Information about a unique "increment" associated with candidates
|
||
having an SSA name for a stride. An increment is the difference
|
||
between the index of the candidate and the index of its basis,
|
||
i.e., (i - i') as discussed in the module commentary.
|
||
|
||
When we are not going to generate address arithmetic we treat
|
||
increments that differ only in sign as the same, allowing sharing
|
||
of the cost of initializers. The absolute value of the increment
|
||
is stored in the incr_info. */
|
||
|
||
struct incr_info_d
|
||
{
|
||
/* The increment that relates a candidate to its basis. */
|
||
double_int incr;
|
||
|
||
/* How many times the increment occurs in the candidate tree. */
|
||
unsigned count;
|
||
|
||
/* Cost of replacing candidates using this increment. Negative and
|
||
zero costs indicate replacement should be performed. */
|
||
int cost;
|
||
|
||
/* If this increment is profitable but is not -1, 0, or 1, it requires
|
||
an initializer T_0 = stride * incr to be found or introduced in the
|
||
nearest common dominator of all candidates. This field holds T_0
|
||
for subsequent use. */
|
||
tree initializer;
|
||
|
||
/* If the initializer was found to already exist, this is the block
|
||
where it was found. */
|
||
basic_block init_bb;
|
||
};
|
||
|
||
typedef struct incr_info_d incr_info, *incr_info_t;
|
||
|
||
/* Candidates are maintained in a vector. If candidate X dominates
|
||
candidate Y, then X appears before Y in the vector; but the
|
||
converse does not necessarily hold. */
|
||
DEF_VEC_P (slsr_cand_t);
|
||
DEF_VEC_ALLOC_P (slsr_cand_t, heap);
|
||
static VEC (slsr_cand_t, heap) *cand_vec;
|
||
|
||
enum cost_consts
|
||
{
|
||
COST_NEUTRAL = 0,
|
||
COST_INFINITE = 1000
|
||
};
|
||
|
||
/* Pointer map embodying a mapping from statements to candidates. */
|
||
static struct pointer_map_t *stmt_cand_map;
|
||
|
||
/* Obstack for candidates. */
|
||
static struct obstack cand_obstack;
|
||
|
||
/* Hash table embodying a mapping from base exprs to chains of candidates. */
|
||
static htab_t base_cand_map;
|
||
|
||
/* Obstack for candidate chains. */
|
||
static struct obstack chain_obstack;
|
||
|
||
/* An array INCR_VEC of incr_infos is used during analysis of related
|
||
candidates having an SSA name for a stride. INCR_VEC_LEN describes
|
||
its current length. */
|
||
static incr_info_t incr_vec;
|
||
static unsigned incr_vec_len;
|
||
|
||
/* For a chain of candidates with unknown stride, indicates whether or not
|
||
we must generate pointer arithmetic when replacing statements. */
|
||
static bool address_arithmetic_p;
|
||
|
||
/* Produce a pointer to the IDX'th candidate in the candidate vector. */
|
||
|
||
static slsr_cand_t
|
||
lookup_cand (cand_idx idx)
|
||
{
|
||
return VEC_index (slsr_cand_t, cand_vec, idx - 1);
|
||
}
|
||
|
||
/* Callback to produce a hash value for a candidate chain header. */
|
||
|
||
static hashval_t
|
||
base_cand_hash (const void *p)
|
||
{
|
||
tree base_expr = ((const_cand_chain_t) p)->base_expr;
|
||
return iterative_hash_expr (base_expr, 0);
|
||
}
|
||
|
||
/* Callback when an element is removed from the hash table.
|
||
We never remove entries until the entire table is released. */
|
||
|
||
static void
|
||
base_cand_free (void *p ATTRIBUTE_UNUSED)
|
||
{
|
||
}
|
||
|
||
/* Callback to return true if two candidate chain headers are equal. */
|
||
|
||
static int
|
||
base_cand_eq (const void *p1, const void *p2)
|
||
{
|
||
const_cand_chain_t const chain1 = (const_cand_chain_t) p1;
|
||
const_cand_chain_t const chain2 = (const_cand_chain_t) p2;
|
||
return operand_equal_p (chain1->base_expr, chain2->base_expr, 0);
|
||
}
|
||
|
||
/* Use the base expr from candidate C to look for possible candidates
|
||
that can serve as a basis for C. Each potential basis must also
|
||
appear in a block that dominates the candidate statement and have
|
||
the same stride and type. If more than one possible basis exists,
|
||
the one with highest index in the vector is chosen; this will be
|
||
the most immediately dominating basis. */
|
||
|
||
static int
|
||
find_basis_for_candidate (slsr_cand_t c)
|
||
{
|
||
cand_chain mapping_key;
|
||
cand_chain_t chain;
|
||
slsr_cand_t basis = NULL;
|
||
|
||
mapping_key.base_expr = c->base_expr;
|
||
chain = (cand_chain_t) htab_find (base_cand_map, &mapping_key);
|
||
|
||
for (; chain; chain = chain->next)
|
||
{
|
||
slsr_cand_t one_basis = chain->cand;
|
||
|
||
if (one_basis->kind != c->kind
|
||
|| !operand_equal_p (one_basis->stride, c->stride, 0)
|
||
|| !types_compatible_p (one_basis->cand_type, c->cand_type)
|
||
|| !dominated_by_p (CDI_DOMINATORS,
|
||
gimple_bb (c->cand_stmt),
|
||
gimple_bb (one_basis->cand_stmt)))
|
||
continue;
|
||
|
||
if (!basis || basis->cand_num < one_basis->cand_num)
|
||
basis = one_basis;
|
||
}
|
||
|
||
if (basis)
|
||
{
|
||
c->sibling = basis->dependent;
|
||
basis->dependent = c->cand_num;
|
||
return basis->cand_num;
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
/* Record a mapping from the base expression of C to C itself, indicating that
|
||
C may potentially serve as a basis using that base expression. */
|
||
|
||
static void
|
||
record_potential_basis (slsr_cand_t c)
|
||
{
|
||
cand_chain_t node;
|
||
void **slot;
|
||
|
||
node = (cand_chain_t) obstack_alloc (&chain_obstack, sizeof (cand_chain));
|
||
node->base_expr = c->base_expr;
|
||
node->cand = c;
|
||
node->next = NULL;
|
||
slot = htab_find_slot (base_cand_map, node, INSERT);
|
||
|
||
if (*slot)
|
||
{
|
||
cand_chain_t head = (cand_chain_t) (*slot);
|
||
node->next = head->next;
|
||
head->next = node;
|
||
}
|
||
else
|
||
*slot = node;
|
||
}
|
||
|
||
/* Allocate storage for a new candidate and initialize its fields.
|
||
Attempt to find a basis for the candidate. */
|
||
|
||
static slsr_cand_t
|
||
alloc_cand_and_find_basis (enum cand_kind kind, gimple gs, tree base,
|
||
double_int index, tree stride, tree ctype,
|
||
unsigned savings)
|
||
{
|
||
slsr_cand_t c = (slsr_cand_t) obstack_alloc (&cand_obstack,
|
||
sizeof (slsr_cand));
|
||
c->cand_stmt = gs;
|
||
c->base_expr = base;
|
||
c->stride = stride;
|
||
c->index = index;
|
||
c->cand_type = ctype;
|
||
c->kind = kind;
|
||
c->cand_num = VEC_length (slsr_cand_t, cand_vec) + 1;
|
||
c->next_interp = 0;
|
||
c->dependent = 0;
|
||
c->sibling = 0;
|
||
c->def_phi = NULL;
|
||
c->dead_savings = savings;
|
||
|
||
VEC_safe_push (slsr_cand_t, heap, cand_vec, c);
|
||
c->basis = find_basis_for_candidate (c);
|
||
record_potential_basis (c);
|
||
|
||
return c;
|
||
}
|
||
|
||
/* Determine the target cost of statement GS when compiling according
|
||
to SPEED. */
|
||
|
||
static int
|
||
stmt_cost (gimple gs, bool speed)
|
||
{
|
||
tree lhs, rhs1, rhs2;
|
||
enum machine_mode lhs_mode;
|
||
|
||
gcc_assert (is_gimple_assign (gs));
|
||
lhs = gimple_assign_lhs (gs);
|
||
rhs1 = gimple_assign_rhs1 (gs);
|
||
lhs_mode = TYPE_MODE (TREE_TYPE (lhs));
|
||
|
||
switch (gimple_assign_rhs_code (gs))
|
||
{
|
||
case MULT_EXPR:
|
||
rhs2 = gimple_assign_rhs2 (gs);
|
||
|
||
if (host_integerp (rhs2, 0))
|
||
return mult_by_coeff_cost (TREE_INT_CST_LOW (rhs2), lhs_mode, speed);
|
||
|
||
gcc_assert (TREE_CODE (rhs1) != INTEGER_CST);
|
||
return mul_cost (speed, lhs_mode);
|
||
|
||
case PLUS_EXPR:
|
||
case POINTER_PLUS_EXPR:
|
||
case MINUS_EXPR:
|
||
return add_cost (speed, lhs_mode);
|
||
|
||
case NEGATE_EXPR:
|
||
return neg_cost (speed, lhs_mode);
|
||
|
||
case NOP_EXPR:
|
||
return convert_cost (lhs_mode, TYPE_MODE (TREE_TYPE (rhs1)), speed);
|
||
|
||
/* Note that we don't assign costs to copies that in most cases
|
||
will go away. */
|
||
default:
|
||
;
|
||
}
|
||
|
||
gcc_unreachable ();
|
||
return 0;
|
||
}
|
||
|
||
/* Look up the defining statement for BASE_IN and return a pointer
|
||
to its candidate in the candidate table, if any; otherwise NULL.
|
||
Only CAND_ADD and CAND_MULT candidates are returned. */
|
||
|
||
static slsr_cand_t
|
||
base_cand_from_table (tree base_in)
|
||
{
|
||
slsr_cand_t *result;
|
||
|
||
gimple def = SSA_NAME_DEF_STMT (base_in);
|
||
if (!def)
|
||
return (slsr_cand_t) NULL;
|
||
|
||
result = (slsr_cand_t *) pointer_map_contains (stmt_cand_map, def);
|
||
|
||
if (result && (*result)->kind != CAND_REF)
|
||
return *result;
|
||
|
||
return (slsr_cand_t) NULL;
|
||
}
|
||
|
||
/* Add an entry to the statement-to-candidate mapping. */
|
||
|
||
static void
|
||
add_cand_for_stmt (gimple gs, slsr_cand_t c)
|
||
{
|
||
void **slot = pointer_map_insert (stmt_cand_map, gs);
|
||
gcc_assert (!*slot);
|
||
*slot = c;
|
||
}
|
||
|
||
/* Look for the following pattern:
|
||
|
||
*PBASE: MEM_REF (T1, C1)
|
||
|
||
*POFFSET: MULT_EXPR (T2, C3) [C2 is zero]
|
||
or
|
||
MULT_EXPR (PLUS_EXPR (T2, C2), C3)
|
||
or
|
||
MULT_EXPR (MINUS_EXPR (T2, -C2), C3)
|
||
|
||
*PINDEX: C4 * BITS_PER_UNIT
|
||
|
||
If not present, leave the input values unchanged and return FALSE.
|
||
Otherwise, modify the input values as follows and return TRUE:
|
||
|
||
*PBASE: T1
|
||
*POFFSET: MULT_EXPR (T2, C3)
|
||
*PINDEX: C1 + (C2 * C3) + C4 */
|
||
|
||
static bool
|
||
restructure_reference (tree *pbase, tree *poffset, double_int *pindex,
|
||
tree *ptype)
|
||
{
|
||
tree base = *pbase, offset = *poffset;
|
||
double_int index = *pindex;
|
||
double_int bpu = uhwi_to_double_int (BITS_PER_UNIT);
|
||
tree mult_op0, mult_op1, t1, t2, type;
|
||
double_int c1, c2, c3, c4;
|
||
|
||
if (!base
|
||
|| !offset
|
||
|| TREE_CODE (base) != MEM_REF
|
||
|| TREE_CODE (offset) != MULT_EXPR
|
||
|| TREE_CODE (TREE_OPERAND (offset, 1)) != INTEGER_CST
|
||
|| !double_int_zero_p (double_int_umod (index, bpu, FLOOR_MOD_EXPR)))
|
||
return false;
|
||
|
||
t1 = TREE_OPERAND (base, 0);
|
||
c1 = mem_ref_offset (base);
|
||
type = TREE_TYPE (TREE_OPERAND (base, 1));
|
||
|
||
mult_op0 = TREE_OPERAND (offset, 0);
|
||
mult_op1 = TREE_OPERAND (offset, 1);
|
||
|
||
c3 = tree_to_double_int (mult_op1);
|
||
|
||
if (TREE_CODE (mult_op0) == PLUS_EXPR)
|
||
|
||
if (TREE_CODE (TREE_OPERAND (mult_op0, 1)) == INTEGER_CST)
|
||
{
|
||
t2 = TREE_OPERAND (mult_op0, 0);
|
||
c2 = tree_to_double_int (TREE_OPERAND (mult_op0, 1));
|
||
}
|
||
else
|
||
return false;
|
||
|
||
else if (TREE_CODE (mult_op0) == MINUS_EXPR)
|
||
|
||
if (TREE_CODE (TREE_OPERAND (mult_op0, 1)) == INTEGER_CST)
|
||
{
|
||
t2 = TREE_OPERAND (mult_op0, 0);
|
||
c2 = double_int_neg (tree_to_double_int (TREE_OPERAND (mult_op0, 1)));
|
||
}
|
||
else
|
||
return false;
|
||
|
||
else
|
||
{
|
||
t2 = mult_op0;
|
||
c2 = double_int_zero;
|
||
}
|
||
|
||
c4 = double_int_udiv (index, bpu, FLOOR_DIV_EXPR);
|
||
|
||
*pbase = t1;
|
||
*poffset = fold_build2 (MULT_EXPR, sizetype, t2,
|
||
double_int_to_tree (sizetype, c3));
|
||
*pindex = double_int_add (double_int_add (c1, double_int_mul (c2, c3)), c4);
|
||
*ptype = type;
|
||
|
||
return true;
|
||
}
|
||
|
||
/* Given GS which contains a data reference, create a CAND_REF entry in
|
||
the candidate table and attempt to find a basis. */
|
||
|
||
static void
|
||
slsr_process_ref (gimple gs)
|
||
{
|
||
tree ref_expr, base, offset, type;
|
||
HOST_WIDE_INT bitsize, bitpos;
|
||
enum machine_mode mode;
|
||
int unsignedp, volatilep;
|
||
double_int index;
|
||
slsr_cand_t c;
|
||
|
||
if (gimple_vdef (gs))
|
||
ref_expr = gimple_assign_lhs (gs);
|
||
else
|
||
ref_expr = gimple_assign_rhs1 (gs);
|
||
|
||
if (!handled_component_p (ref_expr)
|
||
|| TREE_CODE (ref_expr) == BIT_FIELD_REF
|
||
|| (TREE_CODE (ref_expr) == COMPONENT_REF
|
||
&& DECL_BIT_FIELD (TREE_OPERAND (ref_expr, 1))))
|
||
return;
|
||
|
||
base = get_inner_reference (ref_expr, &bitsize, &bitpos, &offset, &mode,
|
||
&unsignedp, &volatilep, false);
|
||
index = uhwi_to_double_int (bitpos);
|
||
|
||
if (!restructure_reference (&base, &offset, &index, &type))
|
||
return;
|
||
|
||
c = alloc_cand_and_find_basis (CAND_REF, gs, base, index, offset,
|
||
type, 0);
|
||
|
||
/* Add the candidate to the statement-candidate mapping. */
|
||
add_cand_for_stmt (gs, c);
|
||
}
|
||
|
||
/* Create a candidate entry for a statement GS, where GS multiplies
|
||
two SSA names BASE_IN and STRIDE_IN. Propagate any known information
|
||
about the two SSA names into the new candidate. Return the new
|
||
candidate. */
|
||
|
||
static slsr_cand_t
|
||
create_mul_ssa_cand (gimple gs, tree base_in, tree stride_in, bool speed)
|
||
{
|
||
tree base = NULL_TREE, stride = NULL_TREE, ctype = NULL_TREE;
|
||
double_int index;
|
||
unsigned savings = 0;
|
||
slsr_cand_t c;
|
||
slsr_cand_t base_cand = base_cand_from_table (base_in);
|
||
|
||
/* Look at all interpretations of the base candidate, if necessary,
|
||
to find information to propagate into this candidate. */
|
||
while (base_cand && !base)
|
||
{
|
||
|
||
if (base_cand->kind == CAND_MULT
|
||
&& operand_equal_p (base_cand->stride, integer_one_node, 0))
|
||
{
|
||
/* Y = (B + i') * 1
|
||
X = Y * Z
|
||
================
|
||
X = (B + i') * Z */
|
||
base = base_cand->base_expr;
|
||
index = base_cand->index;
|
||
stride = stride_in;
|
||
ctype = base_cand->cand_type;
|
||
if (has_single_use (base_in))
|
||
savings = (base_cand->dead_savings
|
||
+ stmt_cost (base_cand->cand_stmt, speed));
|
||
}
|
||
else if (base_cand->kind == CAND_ADD
|
||
&& TREE_CODE (base_cand->stride) == INTEGER_CST)
|
||
{
|
||
/* Y = B + (i' * S), S constant
|
||
X = Y * Z
|
||
============================
|
||
X = B + ((i' * S) * Z) */
|
||
base = base_cand->base_expr;
|
||
index = double_int_mul (base_cand->index,
|
||
tree_to_double_int (base_cand->stride));
|
||
stride = stride_in;
|
||
ctype = base_cand->cand_type;
|
||
if (has_single_use (base_in))
|
||
savings = (base_cand->dead_savings
|
||
+ stmt_cost (base_cand->cand_stmt, speed));
|
||
}
|
||
|
||
if (base_cand->next_interp)
|
||
base_cand = lookup_cand (base_cand->next_interp);
|
||
else
|
||
base_cand = NULL;
|
||
}
|
||
|
||
if (!base)
|
||
{
|
||
/* No interpretations had anything useful to propagate, so
|
||
produce X = (Y + 0) * Z. */
|
||
base = base_in;
|
||
index = double_int_zero;
|
||
stride = stride_in;
|
||
ctype = TREE_TYPE (base_in);
|
||
}
|
||
|
||
c = alloc_cand_and_find_basis (CAND_MULT, gs, base, index, stride,
|
||
ctype, savings);
|
||
return c;
|
||
}
|
||
|
||
/* Create a candidate entry for a statement GS, where GS multiplies
|
||
SSA name BASE_IN by constant STRIDE_IN. Propagate any known
|
||
information about BASE_IN into the new candidate. Return the new
|
||
candidate. */
|
||
|
||
static slsr_cand_t
|
||
create_mul_imm_cand (gimple gs, tree base_in, tree stride_in, bool speed)
|
||
{
|
||
tree base = NULL_TREE, stride = NULL_TREE, ctype = NULL_TREE;
|
||
double_int index, temp;
|
||
unsigned savings = 0;
|
||
slsr_cand_t c;
|
||
slsr_cand_t base_cand = base_cand_from_table (base_in);
|
||
|
||
/* Look at all interpretations of the base candidate, if necessary,
|
||
to find information to propagate into this candidate. */
|
||
while (base_cand && !base)
|
||
{
|
||
if (base_cand->kind == CAND_MULT
|
||
&& TREE_CODE (base_cand->stride) == INTEGER_CST)
|
||
{
|
||
/* Y = (B + i') * S, S constant
|
||
X = Y * c
|
||
============================
|
||
X = (B + i') * (S * c) */
|
||
base = base_cand->base_expr;
|
||
index = base_cand->index;
|
||
temp = double_int_mul (tree_to_double_int (base_cand->stride),
|
||
tree_to_double_int (stride_in));
|
||
stride = double_int_to_tree (TREE_TYPE (stride_in), temp);
|
||
ctype = base_cand->cand_type;
|
||
if (has_single_use (base_in))
|
||
savings = (base_cand->dead_savings
|
||
+ stmt_cost (base_cand->cand_stmt, speed));
|
||
}
|
||
else if (base_cand->kind == CAND_ADD
|
||
&& operand_equal_p (base_cand->stride, integer_one_node, 0))
|
||
{
|
||
/* Y = B + (i' * 1)
|
||
X = Y * c
|
||
===========================
|
||
X = (B + i') * c */
|
||
base = base_cand->base_expr;
|
||
index = base_cand->index;
|
||
stride = stride_in;
|
||
ctype = base_cand->cand_type;
|
||
if (has_single_use (base_in))
|
||
savings = (base_cand->dead_savings
|
||
+ stmt_cost (base_cand->cand_stmt, speed));
|
||
}
|
||
else if (base_cand->kind == CAND_ADD
|
||
&& double_int_one_p (base_cand->index)
|
||
&& TREE_CODE (base_cand->stride) == INTEGER_CST)
|
||
{
|
||
/* Y = B + (1 * S), S constant
|
||
X = Y * c
|
||
===========================
|
||
X = (B + S) * c */
|
||
base = base_cand->base_expr;
|
||
index = tree_to_double_int (base_cand->stride);
|
||
stride = stride_in;
|
||
ctype = base_cand->cand_type;
|
||
if (has_single_use (base_in))
|
||
savings = (base_cand->dead_savings
|
||
+ stmt_cost (base_cand->cand_stmt, speed));
|
||
}
|
||
|
||
if (base_cand->next_interp)
|
||
base_cand = lookup_cand (base_cand->next_interp);
|
||
else
|
||
base_cand = NULL;
|
||
}
|
||
|
||
if (!base)
|
||
{
|
||
/* No interpretations had anything useful to propagate, so
|
||
produce X = (Y + 0) * c. */
|
||
base = base_in;
|
||
index = double_int_zero;
|
||
stride = stride_in;
|
||
ctype = TREE_TYPE (base_in);
|
||
}
|
||
|
||
c = alloc_cand_and_find_basis (CAND_MULT, gs, base, index, stride,
|
||
ctype, savings);
|
||
return c;
|
||
}
|
||
|
||
/* Given GS which is a multiply of scalar integers, make an appropriate
|
||
entry in the candidate table. If this is a multiply of two SSA names,
|
||
create two CAND_MULT interpretations and attempt to find a basis for
|
||
each of them. Otherwise, create a single CAND_MULT and attempt to
|
||
find a basis. */
|
||
|
||
static void
|
||
slsr_process_mul (gimple gs, tree rhs1, tree rhs2, bool speed)
|
||
{
|
||
slsr_cand_t c, c2;
|
||
|
||
/* If this is a multiply of an SSA name with itself, it is highly
|
||
unlikely that we will get a strength reduction opportunity, so
|
||
don't record it as a candidate. This simplifies the logic for
|
||
finding a basis, so if this is removed that must be considered. */
|
||
if (rhs1 == rhs2)
|
||
return;
|
||
|
||
if (TREE_CODE (rhs2) == SSA_NAME)
|
||
{
|
||
/* Record an interpretation of this statement in the candidate table
|
||
assuming RHS1 is the base expression and RHS2 is the stride. */
|
||
c = create_mul_ssa_cand (gs, rhs1, rhs2, speed);
|
||
|
||
/* Add the first interpretation to the statement-candidate mapping. */
|
||
add_cand_for_stmt (gs, c);
|
||
|
||
/* Record another interpretation of this statement assuming RHS1
|
||
is the stride and RHS2 is the base expression. */
|
||
c2 = create_mul_ssa_cand (gs, rhs2, rhs1, speed);
|
||
c->next_interp = c2->cand_num;
|
||
}
|
||
else
|
||
{
|
||
/* Record an interpretation for the multiply-immediate. */
|
||
c = create_mul_imm_cand (gs, rhs1, rhs2, speed);
|
||
|
||
/* Add the interpretation to the statement-candidate mapping. */
|
||
add_cand_for_stmt (gs, c);
|
||
}
|
||
}
|
||
|
||
/* Create a candidate entry for a statement GS, where GS adds two
|
||
SSA names BASE_IN and ADDEND_IN if SUBTRACT_P is false, and
|
||
subtracts ADDEND_IN from BASE_IN otherwise. Propagate any known
|
||
information about the two SSA names into the new candidate.
|
||
Return the new candidate. */
|
||
|
||
static slsr_cand_t
|
||
create_add_ssa_cand (gimple gs, tree base_in, tree addend_in,
|
||
bool subtract_p, bool speed)
|
||
{
|
||
tree base = NULL_TREE, stride = NULL_TREE, ctype = NULL;
|
||
double_int index;
|
||
unsigned savings = 0;
|
||
slsr_cand_t c;
|
||
slsr_cand_t base_cand = base_cand_from_table (base_in);
|
||
slsr_cand_t addend_cand = base_cand_from_table (addend_in);
|
||
|
||
/* The most useful transformation is a multiply-immediate feeding
|
||
an add or subtract. Look for that first. */
|
||
while (addend_cand && !base)
|
||
{
|
||
if (addend_cand->kind == CAND_MULT
|
||
&& double_int_zero_p (addend_cand->index)
|
||
&& TREE_CODE (addend_cand->stride) == INTEGER_CST)
|
||
{
|
||
/* Z = (B + 0) * S, S constant
|
||
X = Y +/- Z
|
||
===========================
|
||
X = Y + ((+/-1 * S) * B) */
|
||
base = base_in;
|
||
index = tree_to_double_int (addend_cand->stride);
|
||
if (subtract_p)
|
||
index = double_int_neg (index);
|
||
stride = addend_cand->base_expr;
|
||
ctype = TREE_TYPE (base_in);
|
||
if (has_single_use (addend_in))
|
||
savings = (addend_cand->dead_savings
|
||
+ stmt_cost (addend_cand->cand_stmt, speed));
|
||
}
|
||
|
||
if (addend_cand->next_interp)
|
||
addend_cand = lookup_cand (addend_cand->next_interp);
|
||
else
|
||
addend_cand = NULL;
|
||
}
|
||
|
||
while (base_cand && !base)
|
||
{
|
||
if (base_cand->kind == CAND_ADD
|
||
&& (double_int_zero_p (base_cand->index)
|
||
|| operand_equal_p (base_cand->stride,
|
||
integer_zero_node, 0)))
|
||
{
|
||
/* Y = B + (i' * S), i' * S = 0
|
||
X = Y +/- Z
|
||
============================
|
||
X = B + (+/-1 * Z) */
|
||
base = base_cand->base_expr;
|
||
index = subtract_p ? double_int_minus_one : double_int_one;
|
||
stride = addend_in;
|
||
ctype = base_cand->cand_type;
|
||
if (has_single_use (base_in))
|
||
savings = (base_cand->dead_savings
|
||
+ stmt_cost (base_cand->cand_stmt, speed));
|
||
}
|
||
else if (subtract_p)
|
||
{
|
||
slsr_cand_t subtrahend_cand = base_cand_from_table (addend_in);
|
||
|
||
while (subtrahend_cand && !base)
|
||
{
|
||
if (subtrahend_cand->kind == CAND_MULT
|
||
&& double_int_zero_p (subtrahend_cand->index)
|
||
&& TREE_CODE (subtrahend_cand->stride) == INTEGER_CST)
|
||
{
|
||
/* Z = (B + 0) * S, S constant
|
||
X = Y - Z
|
||
===========================
|
||
Value: X = Y + ((-1 * S) * B) */
|
||
base = base_in;
|
||
index = tree_to_double_int (subtrahend_cand->stride);
|
||
index = double_int_neg (index);
|
||
stride = subtrahend_cand->base_expr;
|
||
ctype = TREE_TYPE (base_in);
|
||
if (has_single_use (addend_in))
|
||
savings = (subtrahend_cand->dead_savings
|
||
+ stmt_cost (subtrahend_cand->cand_stmt, speed));
|
||
}
|
||
|
||
if (subtrahend_cand->next_interp)
|
||
subtrahend_cand = lookup_cand (subtrahend_cand->next_interp);
|
||
else
|
||
subtrahend_cand = NULL;
|
||
}
|
||
}
|
||
|
||
if (base_cand->next_interp)
|
||
base_cand = lookup_cand (base_cand->next_interp);
|
||
else
|
||
base_cand = NULL;
|
||
}
|
||
|
||
if (!base)
|
||
{
|
||
/* No interpretations had anything useful to propagate, so
|
||
produce X = Y + (1 * Z). */
|
||
base = base_in;
|
||
index = subtract_p ? double_int_minus_one : double_int_one;
|
||
stride = addend_in;
|
||
ctype = TREE_TYPE (base_in);
|
||
}
|
||
|
||
c = alloc_cand_and_find_basis (CAND_ADD, gs, base, index, stride,
|
||
ctype, savings);
|
||
return c;
|
||
}
|
||
|
||
/* Create a candidate entry for a statement GS, where GS adds SSA
|
||
name BASE_IN to constant INDEX_IN. Propagate any known information
|
||
about BASE_IN into the new candidate. Return the new candidate. */
|
||
|
||
static slsr_cand_t
|
||
create_add_imm_cand (gimple gs, tree base_in, double_int index_in, bool speed)
|
||
{
|
||
enum cand_kind kind = CAND_ADD;
|
||
tree base = NULL_TREE, stride = NULL_TREE, ctype = NULL_TREE;
|
||
double_int index, multiple;
|
||
unsigned savings = 0;
|
||
slsr_cand_t c;
|
||
slsr_cand_t base_cand = base_cand_from_table (base_in);
|
||
|
||
while (base_cand && !base)
|
||
{
|
||
bool unsigned_p = TYPE_UNSIGNED (TREE_TYPE (base_cand->stride));
|
||
|
||
if (TREE_CODE (base_cand->stride) == INTEGER_CST
|
||
&& double_int_multiple_of (index_in,
|
||
tree_to_double_int (base_cand->stride),
|
||
unsigned_p,
|
||
&multiple))
|
||
{
|
||
/* Y = (B + i') * S, S constant, c = kS for some integer k
|
||
X = Y + c
|
||
============================
|
||
X = (B + (i'+ k)) * S
|
||
OR
|
||
Y = B + (i' * S), S constant, c = kS for some integer k
|
||
X = Y + c
|
||
============================
|
||
X = (B + (i'+ k)) * S */
|
||
kind = base_cand->kind;
|
||
base = base_cand->base_expr;
|
||
index = double_int_add (base_cand->index, multiple);
|
||
stride = base_cand->stride;
|
||
ctype = base_cand->cand_type;
|
||
if (has_single_use (base_in))
|
||
savings = (base_cand->dead_savings
|
||
+ stmt_cost (base_cand->cand_stmt, speed));
|
||
}
|
||
|
||
if (base_cand->next_interp)
|
||
base_cand = lookup_cand (base_cand->next_interp);
|
||
else
|
||
base_cand = NULL;
|
||
}
|
||
|
||
if (!base)
|
||
{
|
||
/* No interpretations had anything useful to propagate, so
|
||
produce X = Y + (c * 1). */
|
||
kind = CAND_ADD;
|
||
base = base_in;
|
||
index = index_in;
|
||
stride = integer_one_node;
|
||
ctype = TREE_TYPE (base_in);
|
||
}
|
||
|
||
c = alloc_cand_and_find_basis (kind, gs, base, index, stride,
|
||
ctype, savings);
|
||
return c;
|
||
}
|
||
|
||
/* Given GS which is an add or subtract of scalar integers or pointers,
|
||
make at least one appropriate entry in the candidate table. */
|
||
|
||
static void
|
||
slsr_process_add (gimple gs, tree rhs1, tree rhs2, bool speed)
|
||
{
|
||
bool subtract_p = gimple_assign_rhs_code (gs) == MINUS_EXPR;
|
||
slsr_cand_t c = NULL, c2;
|
||
|
||
if (TREE_CODE (rhs2) == SSA_NAME)
|
||
{
|
||
/* First record an interpretation assuming RHS1 is the base expression
|
||
and RHS2 is the stride. But it doesn't make sense for the
|
||
stride to be a pointer, so don't record a candidate in that case. */
|
||
if (!POINTER_TYPE_P (TREE_TYPE (rhs2)))
|
||
{
|
||
c = create_add_ssa_cand (gs, rhs1, rhs2, subtract_p, speed);
|
||
|
||
/* Add the first interpretation to the statement-candidate
|
||
mapping. */
|
||
add_cand_for_stmt (gs, c);
|
||
}
|
||
|
||
/* If the two RHS operands are identical, or this is a subtract,
|
||
we're done. */
|
||
if (operand_equal_p (rhs1, rhs2, 0) || subtract_p)
|
||
return;
|
||
|
||
/* Otherwise, record another interpretation assuming RHS2 is the
|
||
base expression and RHS1 is the stride, again provided that the
|
||
stride is not a pointer. */
|
||
if (!POINTER_TYPE_P (TREE_TYPE (rhs1)))
|
||
{
|
||
c2 = create_add_ssa_cand (gs, rhs2, rhs1, false, speed);
|
||
if (c)
|
||
c->next_interp = c2->cand_num;
|
||
else
|
||
add_cand_for_stmt (gs, c2);
|
||
}
|
||
}
|
||
else
|
||
{
|
||
double_int index;
|
||
|
||
/* Record an interpretation for the add-immediate. */
|
||
index = tree_to_double_int (rhs2);
|
||
if (subtract_p)
|
||
index = double_int_neg (index);
|
||
|
||
c = create_add_imm_cand (gs, rhs1, index, speed);
|
||
|
||
/* Add the interpretation to the statement-candidate mapping. */
|
||
add_cand_for_stmt (gs, c);
|
||
}
|
||
}
|
||
|
||
/* Given GS which is a negate of a scalar integer, make an appropriate
|
||
entry in the candidate table. A negate is equivalent to a multiply
|
||
by -1. */
|
||
|
||
static void
|
||
slsr_process_neg (gimple gs, tree rhs1, bool speed)
|
||
{
|
||
/* Record a CAND_MULT interpretation for the multiply by -1. */
|
||
slsr_cand_t c = create_mul_imm_cand (gs, rhs1, integer_minus_one_node, speed);
|
||
|
||
/* Add the interpretation to the statement-candidate mapping. */
|
||
add_cand_for_stmt (gs, c);
|
||
}
|
||
|
||
/* Help function for legal_cast_p, operating on two trees. Checks
|
||
whether it's allowable to cast from RHS to LHS. See legal_cast_p
|
||
for more details. */
|
||
|
||
static bool
|
||
legal_cast_p_1 (tree lhs, tree rhs)
|
||
{
|
||
tree lhs_type, rhs_type;
|
||
unsigned lhs_size, rhs_size;
|
||
bool lhs_wraps, rhs_wraps;
|
||
|
||
lhs_type = TREE_TYPE (lhs);
|
||
rhs_type = TREE_TYPE (rhs);
|
||
lhs_size = TYPE_PRECISION (lhs_type);
|
||
rhs_size = TYPE_PRECISION (rhs_type);
|
||
lhs_wraps = TYPE_OVERFLOW_WRAPS (lhs_type);
|
||
rhs_wraps = TYPE_OVERFLOW_WRAPS (rhs_type);
|
||
|
||
if (lhs_size < rhs_size
|
||
|| (rhs_wraps && !lhs_wraps)
|
||
|| (rhs_wraps && lhs_wraps && rhs_size != lhs_size))
|
||
return false;
|
||
|
||
return true;
|
||
}
|
||
|
||
/* Return TRUE if GS is a statement that defines an SSA name from
|
||
a conversion and is legal for us to combine with an add and multiply
|
||
in the candidate table. For example, suppose we have:
|
||
|
||
A = B + i;
|
||
C = (type) A;
|
||
D = C * S;
|
||
|
||
Without the type-cast, we would create a CAND_MULT for D with base B,
|
||
index i, and stride S. We want to record this candidate only if it
|
||
is equivalent to apply the type cast following the multiply:
|
||
|
||
A = B + i;
|
||
E = A * S;
|
||
D = (type) E;
|
||
|
||
We will record the type with the candidate for D. This allows us
|
||
to use a similar previous candidate as a basis. If we have earlier seen
|
||
|
||
A' = B + i';
|
||
C' = (type) A';
|
||
D' = C' * S;
|
||
|
||
we can replace D with
|
||
|
||
D = D' + (i - i') * S;
|
||
|
||
But if moving the type-cast would change semantics, we mustn't do this.
|
||
|
||
This is legitimate for casts from a non-wrapping integral type to
|
||
any integral type of the same or larger size. It is not legitimate
|
||
to convert a wrapping type to a non-wrapping type, or to a wrapping
|
||
type of a different size. I.e., with a wrapping type, we must
|
||
assume that the addition B + i could wrap, in which case performing
|
||
the multiply before or after one of the "illegal" type casts will
|
||
have different semantics. */
|
||
|
||
static bool
|
||
legal_cast_p (gimple gs, tree rhs)
|
||
{
|
||
if (!is_gimple_assign (gs)
|
||
|| !CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (gs)))
|
||
return false;
|
||
|
||
return legal_cast_p_1 (gimple_assign_lhs (gs), rhs);
|
||
}
|
||
|
||
/* Given GS which is a cast to a scalar integer type, determine whether
|
||
the cast is legal for strength reduction. If so, make at least one
|
||
appropriate entry in the candidate table. */
|
||
|
||
static void
|
||
slsr_process_cast (gimple gs, tree rhs1, bool speed)
|
||
{
|
||
tree lhs, ctype;
|
||
slsr_cand_t base_cand, c, c2;
|
||
unsigned savings = 0;
|
||
|
||
if (!legal_cast_p (gs, rhs1))
|
||
return;
|
||
|
||
lhs = gimple_assign_lhs (gs);
|
||
base_cand = base_cand_from_table (rhs1);
|
||
ctype = TREE_TYPE (lhs);
|
||
|
||
if (base_cand)
|
||
{
|
||
while (base_cand)
|
||
{
|
||
/* Propagate all data from the base candidate except the type,
|
||
which comes from the cast, and the base candidate's cast,
|
||
which is no longer applicable. */
|
||
if (has_single_use (rhs1))
|
||
savings = (base_cand->dead_savings
|
||
+ stmt_cost (base_cand->cand_stmt, speed));
|
||
|
||
c = alloc_cand_and_find_basis (base_cand->kind, gs,
|
||
base_cand->base_expr,
|
||
base_cand->index, base_cand->stride,
|
||
ctype, savings);
|
||
if (base_cand->next_interp)
|
||
base_cand = lookup_cand (base_cand->next_interp);
|
||
else
|
||
base_cand = NULL;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
/* If nothing is known about the RHS, create fresh CAND_ADD and
|
||
CAND_MULT interpretations:
|
||
|
||
X = Y + (0 * 1)
|
||
X = (Y + 0) * 1
|
||
|
||
The first of these is somewhat arbitrary, but the choice of
|
||
1 for the stride simplifies the logic for propagating casts
|
||
into their uses. */
|
||
c = alloc_cand_and_find_basis (CAND_ADD, gs, rhs1, double_int_zero,
|
||
integer_one_node, ctype, 0);
|
||
c2 = alloc_cand_and_find_basis (CAND_MULT, gs, rhs1, double_int_zero,
|
||
integer_one_node, ctype, 0);
|
||
c->next_interp = c2->cand_num;
|
||
}
|
||
|
||
/* Add the first (or only) interpretation to the statement-candidate
|
||
mapping. */
|
||
add_cand_for_stmt (gs, c);
|
||
}
|
||
|
||
/* Given GS which is a copy of a scalar integer type, make at least one
|
||
appropriate entry in the candidate table.
|
||
|
||
This interface is included for completeness, but is unnecessary
|
||
if this pass immediately follows a pass that performs copy
|
||
propagation, such as DOM. */
|
||
|
||
static void
|
||
slsr_process_copy (gimple gs, tree rhs1, bool speed)
|
||
{
|
||
slsr_cand_t base_cand, c, c2;
|
||
unsigned savings = 0;
|
||
|
||
base_cand = base_cand_from_table (rhs1);
|
||
|
||
if (base_cand)
|
||
{
|
||
while (base_cand)
|
||
{
|
||
/* Propagate all data from the base candidate. */
|
||
if (has_single_use (rhs1))
|
||
savings = (base_cand->dead_savings
|
||
+ stmt_cost (base_cand->cand_stmt, speed));
|
||
|
||
c = alloc_cand_and_find_basis (base_cand->kind, gs,
|
||
base_cand->base_expr,
|
||
base_cand->index, base_cand->stride,
|
||
base_cand->cand_type, savings);
|
||
if (base_cand->next_interp)
|
||
base_cand = lookup_cand (base_cand->next_interp);
|
||
else
|
||
base_cand = NULL;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
/* If nothing is known about the RHS, create fresh CAND_ADD and
|
||
CAND_MULT interpretations:
|
||
|
||
X = Y + (0 * 1)
|
||
X = (Y + 0) * 1
|
||
|
||
The first of these is somewhat arbitrary, but the choice of
|
||
1 for the stride simplifies the logic for propagating casts
|
||
into their uses. */
|
||
c = alloc_cand_and_find_basis (CAND_ADD, gs, rhs1, double_int_zero,
|
||
integer_one_node, TREE_TYPE (rhs1), 0);
|
||
c2 = alloc_cand_and_find_basis (CAND_MULT, gs, rhs1, double_int_zero,
|
||
integer_one_node, TREE_TYPE (rhs1), 0);
|
||
c->next_interp = c2->cand_num;
|
||
}
|
||
|
||
/* Add the first (or only) interpretation to the statement-candidate
|
||
mapping. */
|
||
add_cand_for_stmt (gs, c);
|
||
}
|
||
|
||
/* Find strength-reduction candidates in block BB. */
|
||
|
||
static void
|
||
find_candidates_in_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
|
||
basic_block bb)
|
||
{
|
||
bool speed = optimize_bb_for_speed_p (bb);
|
||
gimple_stmt_iterator gsi;
|
||
|
||
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
|
||
{
|
||
gimple gs = gsi_stmt (gsi);
|
||
|
||
if (gimple_vuse (gs) && gimple_assign_single_p (gs))
|
||
slsr_process_ref (gs);
|
||
|
||
else if (is_gimple_assign (gs)
|
||
&& SCALAR_INT_MODE_P
|
||
(TYPE_MODE (TREE_TYPE (gimple_assign_lhs (gs)))))
|
||
{
|
||
tree rhs1 = NULL_TREE, rhs2 = NULL_TREE;
|
||
|
||
switch (gimple_assign_rhs_code (gs))
|
||
{
|
||
case MULT_EXPR:
|
||
case PLUS_EXPR:
|
||
rhs1 = gimple_assign_rhs1 (gs);
|
||
rhs2 = gimple_assign_rhs2 (gs);
|
||
/* Should never happen, but currently some buggy situations
|
||
in earlier phases put constants in rhs1. */
|
||
if (TREE_CODE (rhs1) != SSA_NAME)
|
||
continue;
|
||
break;
|
||
|
||
/* Possible future opportunity: rhs1 of a ptr+ can be
|
||
an ADDR_EXPR. */
|
||
case POINTER_PLUS_EXPR:
|
||
case MINUS_EXPR:
|
||
rhs2 = gimple_assign_rhs2 (gs);
|
||
/* Fall-through. */
|
||
|
||
case NOP_EXPR:
|
||
case MODIFY_EXPR:
|
||
case NEGATE_EXPR:
|
||
rhs1 = gimple_assign_rhs1 (gs);
|
||
if (TREE_CODE (rhs1) != SSA_NAME)
|
||
continue;
|
||
break;
|
||
|
||
default:
|
||
;
|
||
}
|
||
|
||
switch (gimple_assign_rhs_code (gs))
|
||
{
|
||
case MULT_EXPR:
|
||
slsr_process_mul (gs, rhs1, rhs2, speed);
|
||
break;
|
||
|
||
case PLUS_EXPR:
|
||
case POINTER_PLUS_EXPR:
|
||
case MINUS_EXPR:
|
||
slsr_process_add (gs, rhs1, rhs2, speed);
|
||
break;
|
||
|
||
case NEGATE_EXPR:
|
||
slsr_process_neg (gs, rhs1, speed);
|
||
break;
|
||
|
||
case NOP_EXPR:
|
||
slsr_process_cast (gs, rhs1, speed);
|
||
break;
|
||
|
||
case MODIFY_EXPR:
|
||
slsr_process_copy (gs, rhs1, speed);
|
||
break;
|
||
|
||
default:
|
||
;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Dump a candidate for debug. */
|
||
|
||
static void
|
||
dump_candidate (slsr_cand_t c)
|
||
{
|
||
fprintf (dump_file, "%3d [%d] ", c->cand_num,
|
||
gimple_bb (c->cand_stmt)->index);
|
||
print_gimple_stmt (dump_file, c->cand_stmt, 0, 0);
|
||
switch (c->kind)
|
||
{
|
||
case CAND_MULT:
|
||
fputs (" MULT : (", dump_file);
|
||
print_generic_expr (dump_file, c->base_expr, 0);
|
||
fputs (" + ", dump_file);
|
||
dump_double_int (dump_file, c->index, false);
|
||
fputs (") * ", dump_file);
|
||
print_generic_expr (dump_file, c->stride, 0);
|
||
fputs (" : ", dump_file);
|
||
break;
|
||
case CAND_ADD:
|
||
fputs (" ADD : ", dump_file);
|
||
print_generic_expr (dump_file, c->base_expr, 0);
|
||
fputs (" + (", dump_file);
|
||
dump_double_int (dump_file, c->index, false);
|
||
fputs (" * ", dump_file);
|
||
print_generic_expr (dump_file, c->stride, 0);
|
||
fputs (") : ", dump_file);
|
||
break;
|
||
case CAND_REF:
|
||
fputs (" REF : ", dump_file);
|
||
print_generic_expr (dump_file, c->base_expr, 0);
|
||
fputs (" + (", dump_file);
|
||
print_generic_expr (dump_file, c->stride, 0);
|
||
fputs (") + ", dump_file);
|
||
dump_double_int (dump_file, c->index, false);
|
||
fputs (" : ", dump_file);
|
||
break;
|
||
default:
|
||
gcc_unreachable ();
|
||
}
|
||
print_generic_expr (dump_file, c->cand_type, 0);
|
||
fprintf (dump_file, "\n basis: %d dependent: %d sibling: %d\n",
|
||
c->basis, c->dependent, c->sibling);
|
||
fprintf (dump_file, " next-interp: %d dead-savings: %d\n",
|
||
c->next_interp, c->dead_savings);
|
||
if (c->def_phi)
|
||
{
|
||
fputs (" phi: ", dump_file);
|
||
print_gimple_stmt (dump_file, c->def_phi, 0, 0);
|
||
}
|
||
fputs ("\n", dump_file);
|
||
}
|
||
|
||
/* Dump the candidate vector for debug. */
|
||
|
||
static void
|
||
dump_cand_vec (void)
|
||
{
|
||
unsigned i;
|
||
slsr_cand_t c;
|
||
|
||
fprintf (dump_file, "\nStrength reduction candidate vector:\n\n");
|
||
|
||
FOR_EACH_VEC_ELT (slsr_cand_t, cand_vec, i, c)
|
||
dump_candidate (c);
|
||
}
|
||
|
||
/* Callback used to dump the candidate chains hash table. */
|
||
|
||
static int
|
||
base_cand_dump_callback (void **slot, void *ignored ATTRIBUTE_UNUSED)
|
||
{
|
||
const_cand_chain_t chain = *((const_cand_chain_t *) slot);
|
||
cand_chain_t p;
|
||
|
||
print_generic_expr (dump_file, chain->base_expr, 0);
|
||
fprintf (dump_file, " -> %d", chain->cand->cand_num);
|
||
|
||
for (p = chain->next; p; p = p->next)
|
||
fprintf (dump_file, " -> %d", p->cand->cand_num);
|
||
|
||
fputs ("\n", dump_file);
|
||
return 1;
|
||
}
|
||
|
||
/* Dump the candidate chains. */
|
||
|
||
static void
|
||
dump_cand_chains (void)
|
||
{
|
||
fprintf (dump_file, "\nStrength reduction candidate chains:\n\n");
|
||
htab_traverse_noresize (base_cand_map, base_cand_dump_callback, NULL);
|
||
fputs ("\n", dump_file);
|
||
}
|
||
|
||
/* Dump the increment vector for debug. */
|
||
|
||
static void
|
||
dump_incr_vec (void)
|
||
{
|
||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||
{
|
||
unsigned i;
|
||
|
||
fprintf (dump_file, "\nIncrement vector:\n\n");
|
||
|
||
for (i = 0; i < incr_vec_len; i++)
|
||
{
|
||
fprintf (dump_file, "%3d increment: ", i);
|
||
dump_double_int (dump_file, incr_vec[i].incr, false);
|
||
fprintf (dump_file, "\n count: %d", incr_vec[i].count);
|
||
fprintf (dump_file, "\n cost: %d", incr_vec[i].cost);
|
||
fputs ("\n initializer: ", dump_file);
|
||
print_generic_expr (dump_file, incr_vec[i].initializer, 0);
|
||
fputs ("\n\n", dump_file);
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Recursive helper for unconditional_cands_with_known_stride_p.
|
||
Returns TRUE iff C, its siblings, and its dependents are all
|
||
unconditional candidates. */
|
||
|
||
static bool
|
||
unconditional_cands (slsr_cand_t c)
|
||
{
|
||
if (c->def_phi)
|
||
return false;
|
||
|
||
if (c->sibling && !unconditional_cands (lookup_cand (c->sibling)))
|
||
return false;
|
||
|
||
if (c->dependent && !unconditional_cands (lookup_cand (c->dependent)))
|
||
return false;
|
||
|
||
return true;
|
||
}
|
||
|
||
/* Determine whether or not the tree of candidates rooted at
|
||
ROOT consists entirely of unconditional increments with
|
||
an INTEGER_CST stride. */
|
||
|
||
static bool
|
||
unconditional_cands_with_known_stride_p (slsr_cand_t root)
|
||
{
|
||
/* The stride is identical for all related candidates, so
|
||
check it once. */
|
||
if (TREE_CODE (root->stride) != INTEGER_CST)
|
||
return false;
|
||
|
||
return unconditional_cands (lookup_cand (root->dependent));
|
||
}
|
||
|
||
/* Replace *EXPR in candidate C with an equivalent strength-reduced
|
||
data reference. */
|
||
|
||
static void
|
||
replace_ref (tree *expr, slsr_cand_t c)
|
||
{
|
||
tree add_expr = fold_build2 (POINTER_PLUS_EXPR, TREE_TYPE (c->base_expr),
|
||
c->base_expr, c->stride);
|
||
tree mem_ref = fold_build2 (MEM_REF, TREE_TYPE (*expr), add_expr,
|
||
double_int_to_tree (c->cand_type, c->index));
|
||
|
||
/* Gimplify the base addressing expression for the new MEM_REF tree. */
|
||
gimple_stmt_iterator gsi = gsi_for_stmt (c->cand_stmt);
|
||
TREE_OPERAND (mem_ref, 0)
|
||
= force_gimple_operand_gsi (&gsi, TREE_OPERAND (mem_ref, 0),
|
||
/*simple_p=*/true, NULL,
|
||
/*before=*/true, GSI_SAME_STMT);
|
||
copy_ref_info (mem_ref, *expr);
|
||
*expr = mem_ref;
|
||
update_stmt (c->cand_stmt);
|
||
}
|
||
|
||
/* Replace CAND_REF candidate C, each sibling of candidate C, and each
|
||
dependent of candidate C with an equivalent strength-reduced data
|
||
reference. */
|
||
|
||
static void
|
||
replace_refs (slsr_cand_t c)
|
||
{
|
||
if (gimple_vdef (c->cand_stmt))
|
||
{
|
||
tree *lhs = gimple_assign_lhs_ptr (c->cand_stmt);
|
||
replace_ref (lhs, c);
|
||
}
|
||
else
|
||
{
|
||
tree *rhs = gimple_assign_rhs1_ptr (c->cand_stmt);
|
||
replace_ref (rhs, c);
|
||
}
|
||
|
||
if (c->sibling)
|
||
replace_refs (lookup_cand (c->sibling));
|
||
|
||
if (c->dependent)
|
||
replace_refs (lookup_cand (c->dependent));
|
||
}
|
||
|
||
/* Calculate the increment required for candidate C relative to
|
||
its basis. */
|
||
|
||
static double_int
|
||
cand_increment (slsr_cand_t c)
|
||
{
|
||
slsr_cand_t basis;
|
||
|
||
/* If the candidate doesn't have a basis, just return its own
|
||
index. This is useful in record_increments to help us find
|
||
an existing initializer. */
|
||
if (!c->basis)
|
||
return c->index;
|
||
|
||
basis = lookup_cand (c->basis);
|
||
gcc_assert (operand_equal_p (c->base_expr, basis->base_expr, 0));
|
||
return double_int_sub (c->index, basis->index);
|
||
}
|
||
|
||
/* Calculate the increment required for candidate C relative to
|
||
its basis. If we aren't going to generate pointer arithmetic
|
||
for this candidate, return the absolute value of that increment
|
||
instead. */
|
||
|
||
static inline double_int
|
||
cand_abs_increment (slsr_cand_t c)
|
||
{
|
||
double_int increment = cand_increment (c);
|
||
|
||
if (!address_arithmetic_p && double_int_negative_p (increment))
|
||
increment = double_int_neg (increment);
|
||
|
||
return increment;
|
||
}
|
||
|
||
/* If *VAR is NULL or is not of a compatible type with TYPE, create a
|
||
new temporary reg of type TYPE and store it in *VAR. */
|
||
|
||
static inline void
|
||
lazy_create_slsr_reg (tree *var, tree type)
|
||
{
|
||
if (!*var || !types_compatible_p (TREE_TYPE (*var), type))
|
||
*var = create_tmp_reg (type, "slsr");
|
||
}
|
||
|
||
/* Return TRUE iff candidate C has already been replaced under
|
||
another interpretation. */
|
||
|
||
static inline bool
|
||
cand_already_replaced (slsr_cand_t c)
|
||
{
|
||
return (gimple_bb (c->cand_stmt) == 0);
|
||
}
|
||
|
||
/* Helper routine for replace_dependents, doing the work for a
|
||
single candidate C. */
|
||
|
||
static void
|
||
replace_dependent (slsr_cand_t c, enum tree_code cand_code)
|
||
{
|
||
double_int stride = tree_to_double_int (c->stride);
|
||
double_int bump = double_int_mul (cand_increment (c), stride);
|
||
gimple stmt_to_print = NULL;
|
||
slsr_cand_t basis;
|
||
tree basis_name, incr_type, bump_tree;
|
||
enum tree_code code;
|
||
|
||
/* It is highly unlikely, but possible, that the resulting
|
||
bump doesn't fit in a HWI. Abandon the replacement
|
||
in this case. Restriction to signed HWI is conservative
|
||
for unsigned types but allows for safe negation without
|
||
twisted logic. */
|
||
if (!double_int_fits_in_shwi_p (bump))
|
||
return;
|
||
|
||
basis = lookup_cand (c->basis);
|
||
basis_name = gimple_assign_lhs (basis->cand_stmt);
|
||
incr_type = TREE_TYPE (gimple_assign_rhs1 (c->cand_stmt));
|
||
code = PLUS_EXPR;
|
||
|
||
if (double_int_negative_p (bump))
|
||
{
|
||
code = MINUS_EXPR;
|
||
bump = double_int_neg (bump);
|
||
}
|
||
|
||
bump_tree = double_int_to_tree (incr_type, bump);
|
||
|
||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||
{
|
||
fputs ("Replacing: ", dump_file);
|
||
print_gimple_stmt (dump_file, c->cand_stmt, 0, 0);
|
||
}
|
||
|
||
if (double_int_zero_p (bump))
|
||
{
|
||
tree lhs = gimple_assign_lhs (c->cand_stmt);
|
||
gimple copy_stmt = gimple_build_assign (lhs, basis_name);
|
||
gimple_stmt_iterator gsi = gsi_for_stmt (c->cand_stmt);
|
||
gimple_set_location (copy_stmt, gimple_location (c->cand_stmt));
|
||
gsi_replace (&gsi, copy_stmt, false);
|
||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||
stmt_to_print = copy_stmt;
|
||
}
|
||
else
|
||
{
|
||
tree rhs1 = gimple_assign_rhs1 (c->cand_stmt);
|
||
tree rhs2 = gimple_assign_rhs2 (c->cand_stmt);
|
||
if (cand_code != NEGATE_EXPR
|
||
&& ((operand_equal_p (rhs1, basis_name, 0)
|
||
&& operand_equal_p (rhs2, bump_tree, 0))
|
||
|| (operand_equal_p (rhs1, bump_tree, 0)
|
||
&& operand_equal_p (rhs2, basis_name, 0))))
|
||
{
|
||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||
{
|
||
fputs ("(duplicate, not actually replacing)", dump_file);
|
||
stmt_to_print = c->cand_stmt;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
gimple_stmt_iterator gsi = gsi_for_stmt (c->cand_stmt);
|
||
gimple_assign_set_rhs_with_ops (&gsi, code, basis_name, bump_tree);
|
||
update_stmt (gsi_stmt (gsi));
|
||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||
stmt_to_print = gsi_stmt (gsi);
|
||
}
|
||
}
|
||
|
||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||
{
|
||
fputs ("With: ", dump_file);
|
||
print_gimple_stmt (dump_file, stmt_to_print, 0, 0);
|
||
fputs ("\n", dump_file);
|
||
}
|
||
}
|
||
|
||
/* Replace candidate C, each sibling of candidate C, and each
|
||
dependent of candidate C with an add or subtract. Note that we
|
||
only operate on CAND_MULTs with known strides, so we will never
|
||
generate a POINTER_PLUS_EXPR. Each candidate X = (B + i) * S is
|
||
replaced by X = Y + ((i - i') * S), as described in the module
|
||
commentary. The folded value ((i - i') * S) is referred to here
|
||
as the "bump." */
|
||
|
||
static void
|
||
replace_dependents (slsr_cand_t c)
|
||
{
|
||
enum tree_code cand_code = gimple_assign_rhs_code (c->cand_stmt);
|
||
|
||
/* It is not useful to replace casts, copies, or adds of an SSA name
|
||
and a constant. Also skip candidates that have already been
|
||
replaced under another interpretation. */
|
||
if (cand_code != MODIFY_EXPR
|
||
&& cand_code != NOP_EXPR
|
||
&& c->kind == CAND_MULT
|
||
&& !cand_already_replaced (c))
|
||
replace_dependent (c, cand_code);
|
||
|
||
if (c->sibling)
|
||
replace_dependents (lookup_cand (c->sibling));
|
||
|
||
if (c->dependent)
|
||
replace_dependents (lookup_cand (c->dependent));
|
||
}
|
||
|
||
/* Return the index in the increment vector of the given INCREMENT. */
|
||
|
||
static inline unsigned
|
||
incr_vec_index (double_int increment)
|
||
{
|
||
unsigned i;
|
||
|
||
for (i = 0;
|
||
i < incr_vec_len && !double_int_equal_p (increment, incr_vec[i].incr);
|
||
i++)
|
||
;
|
||
|
||
gcc_assert (i < incr_vec_len);
|
||
return i;
|
||
}
|
||
|
||
/* Count the number of candidates in the tree rooted at C that have
|
||
not already been replaced under other interpretations. */
|
||
|
||
static unsigned
|
||
count_candidates (slsr_cand_t c)
|
||
{
|
||
unsigned count = cand_already_replaced (c) ? 0 : 1;
|
||
|
||
if (c->sibling)
|
||
count += count_candidates (lookup_cand (c->sibling));
|
||
|
||
if (c->dependent)
|
||
count += count_candidates (lookup_cand (c->dependent));
|
||
|
||
return count;
|
||
}
|
||
|
||
/* Increase the count of INCREMENT by one in the increment vector.
|
||
INCREMENT is associated with candidate C. If an initializer
|
||
T_0 = stride * I is provided by a candidate that dominates all
|
||
candidates with the same increment, also record T_0 for subsequent use. */
|
||
|
||
static void
|
||
record_increment (slsr_cand_t c, double_int increment)
|
||
{
|
||
bool found = false;
|
||
unsigned i;
|
||
|
||
/* Treat increments that differ only in sign as identical so as to
|
||
share initializers, unless we are generating pointer arithmetic. */
|
||
if (!address_arithmetic_p && double_int_negative_p (increment))
|
||
increment = double_int_neg (increment);
|
||
|
||
for (i = 0; i < incr_vec_len; i++)
|
||
{
|
||
if (double_int_equal_p (incr_vec[i].incr, increment))
|
||
{
|
||
incr_vec[i].count++;
|
||
found = true;
|
||
|
||
/* If we previously recorded an initializer that doesn't
|
||
dominate this candidate, it's not going to be useful to
|
||
us after all. */
|
||
if (incr_vec[i].initializer
|
||
&& !dominated_by_p (CDI_DOMINATORS,
|
||
gimple_bb (c->cand_stmt),
|
||
incr_vec[i].init_bb))
|
||
{
|
||
incr_vec[i].initializer = NULL_TREE;
|
||
incr_vec[i].init_bb = NULL;
|
||
}
|
||
|
||
break;
|
||
}
|
||
}
|
||
|
||
if (!found)
|
||
{
|
||
/* The first time we see an increment, create the entry for it.
|
||
If this is the root candidate which doesn't have a basis, set
|
||
the count to zero. We're only processing it so it can possibly
|
||
provide an initializer for other candidates. */
|
||
incr_vec[incr_vec_len].incr = increment;
|
||
incr_vec[incr_vec_len].count = c->basis ? 1 : 0;
|
||
incr_vec[incr_vec_len].cost = COST_INFINITE;
|
||
|
||
/* Optimistically record the first occurrence of this increment
|
||
as providing an initializer (if it does); we will revise this
|
||
opinion later if it doesn't dominate all other occurrences.
|
||
Exception: increments of -1, 0, 1 never need initializers. */
|
||
if (c->kind == CAND_ADD
|
||
&& double_int_equal_p (c->index, increment)
|
||
&& (double_int_scmp (increment, double_int_one) > 0
|
||
|| double_int_scmp (increment, double_int_minus_one) < 0))
|
||
{
|
||
tree t0;
|
||
tree rhs1 = gimple_assign_rhs1 (c->cand_stmt);
|
||
tree rhs2 = gimple_assign_rhs2 (c->cand_stmt);
|
||
if (operand_equal_p (rhs1, c->base_expr, 0))
|
||
t0 = rhs2;
|
||
else
|
||
t0 = rhs1;
|
||
if (SSA_NAME_DEF_STMT (t0) && gimple_bb (SSA_NAME_DEF_STMT (t0)))
|
||
{
|
||
incr_vec[incr_vec_len].initializer = t0;
|
||
incr_vec[incr_vec_len++].init_bb
|
||
= gimple_bb (SSA_NAME_DEF_STMT (t0));
|
||
}
|
||
else
|
||
{
|
||
incr_vec[incr_vec_len].initializer = NULL_TREE;
|
||
incr_vec[incr_vec_len++].init_bb = NULL;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
incr_vec[incr_vec_len].initializer = NULL_TREE;
|
||
incr_vec[incr_vec_len++].init_bb = NULL;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Determine how many times each unique increment occurs in the set
|
||
of candidates rooted at C's parent, recording the data in the
|
||
increment vector. For each unique increment I, if an initializer
|
||
T_0 = stride * I is provided by a candidate that dominates all
|
||
candidates with the same increment, also record T_0 for subsequent
|
||
use. */
|
||
|
||
static void
|
||
record_increments (slsr_cand_t c)
|
||
{
|
||
if (!cand_already_replaced (c))
|
||
record_increment (c, cand_increment (c));
|
||
|
||
if (c->sibling)
|
||
record_increments (lookup_cand (c->sibling));
|
||
|
||
if (c->dependent)
|
||
record_increments (lookup_cand (c->dependent));
|
||
}
|
||
|
||
/* Return the first candidate in the tree rooted at C that has not
|
||
already been replaced, favoring siblings over dependents. */
|
||
|
||
static slsr_cand_t
|
||
unreplaced_cand_in_tree (slsr_cand_t c)
|
||
{
|
||
if (!cand_already_replaced (c))
|
||
return c;
|
||
|
||
if (c->sibling)
|
||
{
|
||
slsr_cand_t sib = unreplaced_cand_in_tree (lookup_cand (c->sibling));
|
||
if (sib)
|
||
return sib;
|
||
}
|
||
|
||
if (c->dependent)
|
||
{
|
||
slsr_cand_t dep = unreplaced_cand_in_tree (lookup_cand (c->dependent));
|
||
if (dep)
|
||
return dep;
|
||
}
|
||
|
||
return NULL;
|
||
}
|
||
|
||
/* Return TRUE if the candidates in the tree rooted at C should be
|
||
optimized for speed, else FALSE. We estimate this based on the block
|
||
containing the most dominant candidate in the tree that has not yet
|
||
been replaced. */
|
||
|
||
static bool
|
||
optimize_cands_for_speed_p (slsr_cand_t c)
|
||
{
|
||
slsr_cand_t c2 = unreplaced_cand_in_tree (c);
|
||
gcc_assert (c2);
|
||
return optimize_bb_for_speed_p (gimple_bb (c2->cand_stmt));
|
||
}
|
||
|
||
/* Add COST_IN to the lowest cost of any dependent path starting at
|
||
candidate C or any of its siblings, counting only candidates along
|
||
such paths with increment INCR. Assume that replacing a candidate
|
||
reduces cost by REPL_SAVINGS. Also account for savings from any
|
||
statements that would go dead. */
|
||
|
||
static int
|
||
lowest_cost_path (int cost_in, int repl_savings, slsr_cand_t c, double_int incr)
|
||
{
|
||
int local_cost, sib_cost;
|
||
double_int cand_incr = cand_abs_increment (c);
|
||
|
||
if (cand_already_replaced (c))
|
||
local_cost = cost_in;
|
||
else if (double_int_equal_p (incr, cand_incr))
|
||
local_cost = cost_in - repl_savings - c->dead_savings;
|
||
else
|
||
local_cost = cost_in - c->dead_savings;
|
||
|
||
if (c->dependent)
|
||
local_cost = lowest_cost_path (local_cost, repl_savings,
|
||
lookup_cand (c->dependent), incr);
|
||
|
||
if (c->sibling)
|
||
{
|
||
sib_cost = lowest_cost_path (cost_in, repl_savings,
|
||
lookup_cand (c->sibling), incr);
|
||
local_cost = MIN (local_cost, sib_cost);
|
||
}
|
||
|
||
return local_cost;
|
||
}
|
||
|
||
/* Compute the total savings that would accrue from all replacements
|
||
in the candidate tree rooted at C, counting only candidates with
|
||
increment INCR. Assume that replacing a candidate reduces cost
|
||
by REPL_SAVINGS. Also account for savings from statements that
|
||
would go dead. */
|
||
|
||
static int
|
||
total_savings (int repl_savings, slsr_cand_t c, double_int incr)
|
||
{
|
||
int savings = 0;
|
||
double_int cand_incr = cand_abs_increment (c);
|
||
|
||
if (double_int_equal_p (incr, cand_incr)
|
||
&& !cand_already_replaced (c))
|
||
savings += repl_savings + c->dead_savings;
|
||
|
||
if (c->dependent)
|
||
savings += total_savings (repl_savings, lookup_cand (c->dependent), incr);
|
||
|
||
if (c->sibling)
|
||
savings += total_savings (repl_savings, lookup_cand (c->sibling), incr);
|
||
|
||
return savings;
|
||
}
|
||
|
||
/* Use target-specific costs to determine and record which increments
|
||
in the current candidate tree are profitable to replace, assuming
|
||
MODE and SPEED. FIRST_DEP is the first dependent of the root of
|
||
the candidate tree.
|
||
|
||
One slight limitation here is that we don't account for the possible
|
||
introduction of casts in some cases. See replace_one_candidate for
|
||
the cases where these are introduced. This should probably be cleaned
|
||
up sometime. */
|
||
|
||
static void
|
||
analyze_increments (slsr_cand_t first_dep, enum machine_mode mode, bool speed)
|
||
{
|
||
unsigned i;
|
||
|
||
for (i = 0; i < incr_vec_len; i++)
|
||
{
|
||
HOST_WIDE_INT incr = double_int_to_shwi (incr_vec[i].incr);
|
||
|
||
/* If somehow this increment is bigger than a HWI, we won't
|
||
be optimizing candidates that use it. And if the increment
|
||
has a count of zero, nothing will be done with it. */
|
||
if (!double_int_fits_in_shwi_p (incr_vec[i].incr)
|
||
|| !incr_vec[i].count)
|
||
incr_vec[i].cost = COST_INFINITE;
|
||
|
||
/* Increments of 0, 1, and -1 are always profitable to replace,
|
||
because they always replace a multiply or add with an add or
|
||
copy, and may cause one or more existing instructions to go
|
||
dead. Exception: -1 can't be assumed to be profitable for
|
||
pointer addition. */
|
||
else if (incr == 0
|
||
|| incr == 1
|
||
|| (incr == -1
|
||
&& (gimple_assign_rhs_code (first_dep->cand_stmt)
|
||
!= POINTER_PLUS_EXPR)))
|
||
incr_vec[i].cost = COST_NEUTRAL;
|
||
|
||
/* FORNOW: If we need to add an initializer, give up if a cast from
|
||
the candidate's type to its stride's type can lose precision.
|
||
This could eventually be handled better by expressly retaining the
|
||
result of a cast to a wider type in the stride. Example:
|
||
|
||
short int _1;
|
||
_2 = (int) _1;
|
||
_3 = _2 * 10;
|
||
_4 = x + _3; ADD: x + (10 * _1) : int
|
||
_5 = _2 * 15;
|
||
_6 = x + _3; ADD: x + (15 * _1) : int
|
||
|
||
Right now replacing _6 would cause insertion of an initializer
|
||
of the form "short int T = _1 * 5;" followed by a cast to
|
||
int, which could overflow incorrectly. Had we recorded _2 or
|
||
(int)_1 as the stride, this wouldn't happen. However, doing
|
||
this breaks other opportunities, so this will require some
|
||
care. */
|
||
else if (!incr_vec[i].initializer
|
||
&& TREE_CODE (first_dep->stride) != INTEGER_CST
|
||
&& !legal_cast_p_1 (first_dep->stride,
|
||
gimple_assign_lhs (first_dep->cand_stmt)))
|
||
|
||
incr_vec[i].cost = COST_INFINITE;
|
||
|
||
/* For any other increment, if this is a multiply candidate, we
|
||
must introduce a temporary T and initialize it with
|
||
T_0 = stride * increment. When optimizing for speed, walk the
|
||
candidate tree to calculate the best cost reduction along any
|
||
path; if it offsets the fixed cost of inserting the initializer,
|
||
replacing the increment is profitable. When optimizing for
|
||
size, instead calculate the total cost reduction from replacing
|
||
all candidates with this increment. */
|
||
else if (first_dep->kind == CAND_MULT)
|
||
{
|
||
int cost = mult_by_coeff_cost (incr, mode, speed);
|
||
int repl_savings = mul_cost (speed, mode) - add_cost (speed, mode);
|
||
if (speed)
|
||
cost = lowest_cost_path (cost, repl_savings, first_dep,
|
||
incr_vec[i].incr);
|
||
else
|
||
cost -= total_savings (repl_savings, first_dep, incr_vec[i].incr);
|
||
|
||
incr_vec[i].cost = cost;
|
||
}
|
||
|
||
/* If this is an add candidate, the initializer may already
|
||
exist, so only calculate the cost of the initializer if it
|
||
doesn't. We are replacing one add with another here, so the
|
||
known replacement savings is zero. We will account for removal
|
||
of dead instructions in lowest_cost_path or total_savings. */
|
||
else
|
||
{
|
||
int cost = 0;
|
||
if (!incr_vec[i].initializer)
|
||
cost = mult_by_coeff_cost (incr, mode, speed);
|
||
|
||
if (speed)
|
||
cost = lowest_cost_path (cost, 0, first_dep, incr_vec[i].incr);
|
||
else
|
||
cost -= total_savings (0, first_dep, incr_vec[i].incr);
|
||
|
||
incr_vec[i].cost = cost;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Return the nearest common dominator of BB1 and BB2. If the blocks
|
||
are identical, return the earlier of C1 and C2 in *WHERE. Otherwise,
|
||
if the NCD matches BB1, return C1 in *WHERE; if the NCD matches BB2,
|
||
return C2 in *WHERE; and if the NCD matches neither, return NULL in
|
||
*WHERE. Note: It is possible for one of C1 and C2 to be NULL. */
|
||
|
||
static basic_block
|
||
ncd_for_two_cands (basic_block bb1, basic_block bb2,
|
||
slsr_cand_t c1, slsr_cand_t c2, slsr_cand_t *where)
|
||
{
|
||
basic_block ncd;
|
||
|
||
if (!bb1)
|
||
{
|
||
*where = c2;
|
||
return bb2;
|
||
}
|
||
|
||
if (!bb2)
|
||
{
|
||
*where = c1;
|
||
return bb1;
|
||
}
|
||
|
||
ncd = nearest_common_dominator (CDI_DOMINATORS, bb1, bb2);
|
||
|
||
/* If both candidates are in the same block, the earlier
|
||
candidate wins. */
|
||
if (bb1 == ncd && bb2 == ncd)
|
||
{
|
||
if (!c1 || (c2 && c2->cand_num < c1->cand_num))
|
||
*where = c2;
|
||
else
|
||
*where = c1;
|
||
}
|
||
|
||
/* Otherwise, if one of them produced a candidate in the
|
||
dominator, that one wins. */
|
||
else if (bb1 == ncd)
|
||
*where = c1;
|
||
|
||
else if (bb2 == ncd)
|
||
*where = c2;
|
||
|
||
/* If neither matches the dominator, neither wins. */
|
||
else
|
||
*where = NULL;
|
||
|
||
return ncd;
|
||
}
|
||
|
||
/* Consider all candidates in the tree rooted at C for which INCR
|
||
represents the required increment of C relative to its basis.
|
||
Find and return the basic block that most nearly dominates all
|
||
such candidates. If the returned block contains one or more of
|
||
the candidates, return the earliest candidate in the block in
|
||
*WHERE. */
|
||
|
||
static basic_block
|
||
nearest_common_dominator_for_cands (slsr_cand_t c, double_int incr,
|
||
slsr_cand_t *where)
|
||
{
|
||
basic_block sib_ncd = NULL, dep_ncd = NULL, this_ncd = NULL, ncd;
|
||
slsr_cand_t sib_where = NULL, dep_where = NULL, this_where = NULL, new_where;
|
||
double_int cand_incr;
|
||
|
||
/* First find the NCD of all siblings and dependents. */
|
||
if (c->sibling)
|
||
sib_ncd = nearest_common_dominator_for_cands (lookup_cand (c->sibling),
|
||
incr, &sib_where);
|
||
if (c->dependent)
|
||
dep_ncd = nearest_common_dominator_for_cands (lookup_cand (c->dependent),
|
||
incr, &dep_where);
|
||
if (!sib_ncd && !dep_ncd)
|
||
{
|
||
new_where = NULL;
|
||
ncd = NULL;
|
||
}
|
||
else if (sib_ncd && !dep_ncd)
|
||
{
|
||
new_where = sib_where;
|
||
ncd = sib_ncd;
|
||
}
|
||
else if (dep_ncd && !sib_ncd)
|
||
{
|
||
new_where = dep_where;
|
||
ncd = dep_ncd;
|
||
}
|
||
else
|
||
ncd = ncd_for_two_cands (sib_ncd, dep_ncd, sib_where,
|
||
dep_where, &new_where);
|
||
|
||
/* If the candidate's increment doesn't match the one we're interested
|
||
in, then the result depends only on siblings and dependents. */
|
||
cand_incr = cand_abs_increment (c);
|
||
|
||
if (!double_int_equal_p (cand_incr, incr) || cand_already_replaced (c))
|
||
{
|
||
*where = new_where;
|
||
return ncd;
|
||
}
|
||
|
||
/* Otherwise, compare this candidate with the result from all siblings
|
||
and dependents. */
|
||
this_where = c;
|
||
this_ncd = gimple_bb (c->cand_stmt);
|
||
ncd = ncd_for_two_cands (ncd, this_ncd, new_where, this_where, where);
|
||
|
||
return ncd;
|
||
}
|
||
|
||
/* Return TRUE if the increment indexed by INDEX is profitable to replace. */
|
||
|
||
static inline bool
|
||
profitable_increment_p (unsigned index)
|
||
{
|
||
return (incr_vec[index].cost <= COST_NEUTRAL);
|
||
}
|
||
|
||
/* For each profitable increment in the increment vector not equal to
|
||
0 or 1 (or -1, for non-pointer arithmetic), find the nearest common
|
||
dominator of all statements in the candidate chain rooted at C
|
||
that require that increment, and insert an initializer
|
||
T_0 = stride * increment at that location. Record T_0 with the
|
||
increment record. */
|
||
|
||
static void
|
||
insert_initializers (slsr_cand_t c)
|
||
{
|
||
unsigned i;
|
||
tree new_var = NULL_TREE;
|
||
|
||
for (i = 0; i < incr_vec_len; i++)
|
||
{
|
||
basic_block bb;
|
||
slsr_cand_t where = NULL;
|
||
gimple init_stmt;
|
||
tree stride_type, new_name, incr_tree;
|
||
double_int incr = incr_vec[i].incr;
|
||
|
||
if (!profitable_increment_p (i)
|
||
|| double_int_one_p (incr)
|
||
|| (double_int_minus_one_p (incr)
|
||
&& gimple_assign_rhs_code (c->cand_stmt) != POINTER_PLUS_EXPR)
|
||
|| double_int_zero_p (incr))
|
||
continue;
|
||
|
||
/* We may have already identified an existing initializer that
|
||
will suffice. */
|
||
if (incr_vec[i].initializer)
|
||
{
|
||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||
{
|
||
fputs ("Using existing initializer: ", dump_file);
|
||
print_gimple_stmt (dump_file,
|
||
SSA_NAME_DEF_STMT (incr_vec[i].initializer),
|
||
0, 0);
|
||
}
|
||
continue;
|
||
}
|
||
|
||
/* Find the block that most closely dominates all candidates
|
||
with this increment. If there is at least one candidate in
|
||
that block, the earliest one will be returned in WHERE. */
|
||
bb = nearest_common_dominator_for_cands (c, incr, &where);
|
||
|
||
/* Create a new SSA name to hold the initializer's value. */
|
||
stride_type = TREE_TYPE (c->stride);
|
||
lazy_create_slsr_reg (&new_var, stride_type);
|
||
new_name = make_ssa_name (new_var, NULL);
|
||
incr_vec[i].initializer = new_name;
|
||
|
||
/* Create the initializer and insert it in the latest possible
|
||
dominating position. */
|
||
incr_tree = double_int_to_tree (stride_type, incr);
|
||
init_stmt = gimple_build_assign_with_ops (MULT_EXPR, new_name,
|
||
c->stride, incr_tree);
|
||
if (where)
|
||
{
|
||
gimple_stmt_iterator gsi = gsi_for_stmt (where->cand_stmt);
|
||
gsi_insert_before (&gsi, init_stmt, GSI_SAME_STMT);
|
||
gimple_set_location (init_stmt, gimple_location (where->cand_stmt));
|
||
}
|
||
else
|
||
{
|
||
gimple_stmt_iterator gsi = gsi_last_bb (bb);
|
||
gimple basis_stmt = lookup_cand (c->basis)->cand_stmt;
|
||
|
||
if (!gsi_end_p (gsi) && is_ctrl_stmt (gsi_stmt (gsi)))
|
||
gsi_insert_before (&gsi, init_stmt, GSI_SAME_STMT);
|
||
else
|
||
gsi_insert_after (&gsi, init_stmt, GSI_SAME_STMT);
|
||
|
||
gimple_set_location (init_stmt, gimple_location (basis_stmt));
|
||
}
|
||
|
||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||
{
|
||
fputs ("Inserting initializer: ", dump_file);
|
||
print_gimple_stmt (dump_file, init_stmt, 0, 0);
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Create a NOP_EXPR that copies FROM_EXPR into a new SSA name of
|
||
type TO_TYPE, and insert it in front of the statement represented
|
||
by candidate C. Use *NEW_VAR to create the new SSA name. Return
|
||
the new SSA name. */
|
||
|
||
static tree
|
||
introduce_cast_before_cand (slsr_cand_t c, tree to_type,
|
||
tree from_expr, tree *new_var)
|
||
{
|
||
tree cast_lhs;
|
||
gimple cast_stmt;
|
||
gimple_stmt_iterator gsi = gsi_for_stmt (c->cand_stmt);
|
||
|
||
lazy_create_slsr_reg (new_var, to_type);
|
||
cast_lhs = make_ssa_name (*new_var, NULL);
|
||
cast_stmt = gimple_build_assign_with_ops (NOP_EXPR, cast_lhs,
|
||
from_expr, NULL_TREE);
|
||
gimple_set_location (cast_stmt, gimple_location (c->cand_stmt));
|
||
gsi_insert_before (&gsi, cast_stmt, GSI_SAME_STMT);
|
||
|
||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||
{
|
||
fputs (" Inserting: ", dump_file);
|
||
print_gimple_stmt (dump_file, cast_stmt, 0, 0);
|
||
}
|
||
|
||
return cast_lhs;
|
||
}
|
||
|
||
/* Replace the RHS of the statement represented by candidate C with
|
||
NEW_CODE, NEW_RHS1, and NEW_RHS2, provided that to do so doesn't
|
||
leave C unchanged or just interchange its operands. The original
|
||
operation and operands are in OLD_CODE, OLD_RHS1, and OLD_RHS2.
|
||
If the replacement was made and we are doing a details dump,
|
||
return the revised statement, else NULL. */
|
||
|
||
static gimple
|
||
replace_rhs_if_not_dup (enum tree_code new_code, tree new_rhs1, tree new_rhs2,
|
||
enum tree_code old_code, tree old_rhs1, tree old_rhs2,
|
||
slsr_cand_t c)
|
||
{
|
||
if (new_code != old_code
|
||
|| ((!operand_equal_p (new_rhs1, old_rhs1, 0)
|
||
|| !operand_equal_p (new_rhs2, old_rhs2, 0))
|
||
&& (!operand_equal_p (new_rhs1, old_rhs2, 0)
|
||
|| !operand_equal_p (new_rhs2, old_rhs1, 0))))
|
||
{
|
||
gimple_stmt_iterator gsi = gsi_for_stmt (c->cand_stmt);
|
||
gimple_assign_set_rhs_with_ops (&gsi, new_code, new_rhs1, new_rhs2);
|
||
update_stmt (gsi_stmt (gsi));
|
||
|
||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||
return gsi_stmt (gsi);
|
||
}
|
||
|
||
else if (dump_file && (dump_flags & TDF_DETAILS))
|
||
fputs (" (duplicate, not actually replacing)\n", dump_file);
|
||
|
||
return NULL;
|
||
}
|
||
|
||
/* Strength-reduce the statement represented by candidate C by replacing
|
||
it with an equivalent addition or subtraction. I is the index into
|
||
the increment vector identifying C's increment. NEW_VAR is used to
|
||
create a new SSA name if a cast needs to be introduced. BASIS_NAME
|
||
is the rhs1 to use in creating the add/subtract. */
|
||
|
||
static void
|
||
replace_one_candidate (slsr_cand_t c, unsigned i, tree *new_var,
|
||
tree basis_name)
|
||
{
|
||
gimple stmt_to_print = NULL;
|
||
tree orig_rhs1, orig_rhs2;
|
||
tree rhs2;
|
||
enum tree_code orig_code, repl_code;
|
||
double_int cand_incr;
|
||
|
||
orig_code = gimple_assign_rhs_code (c->cand_stmt);
|
||
orig_rhs1 = gimple_assign_rhs1 (c->cand_stmt);
|
||
orig_rhs2 = gimple_assign_rhs2 (c->cand_stmt);
|
||
cand_incr = cand_increment (c);
|
||
|
||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||
{
|
||
fputs ("Replacing: ", dump_file);
|
||
print_gimple_stmt (dump_file, c->cand_stmt, 0, 0);
|
||
stmt_to_print = c->cand_stmt;
|
||
}
|
||
|
||
if (address_arithmetic_p)
|
||
repl_code = POINTER_PLUS_EXPR;
|
||
else
|
||
repl_code = PLUS_EXPR;
|
||
|
||
/* If the increment has an initializer T_0, replace the candidate
|
||
statement with an add of the basis name and the initializer. */
|
||
if (incr_vec[i].initializer)
|
||
{
|
||
tree init_type = TREE_TYPE (incr_vec[i].initializer);
|
||
tree orig_type = TREE_TYPE (orig_rhs2);
|
||
|
||
if (types_compatible_p (orig_type, init_type))
|
||
rhs2 = incr_vec[i].initializer;
|
||
else
|
||
rhs2 = introduce_cast_before_cand (c, orig_type,
|
||
incr_vec[i].initializer,
|
||
new_var);
|
||
|
||
if (!double_int_equal_p (incr_vec[i].incr, cand_incr))
|
||
{
|
||
gcc_assert (repl_code == PLUS_EXPR);
|
||
repl_code = MINUS_EXPR;
|
||
}
|
||
|
||
stmt_to_print = replace_rhs_if_not_dup (repl_code, basis_name, rhs2,
|
||
orig_code, orig_rhs1, orig_rhs2,
|
||
c);
|
||
}
|
||
|
||
/* Otherwise, the increment is one of -1, 0, and 1. Replace
|
||
with a subtract of the stride from the basis name, a copy
|
||
from the basis name, or an add of the stride to the basis
|
||
name, respectively. It may be necessary to introduce a
|
||
cast (or reuse an existing cast). */
|
||
else if (double_int_one_p (cand_incr))
|
||
{
|
||
tree stride_type = TREE_TYPE (c->stride);
|
||
tree orig_type = TREE_TYPE (orig_rhs2);
|
||
|
||
if (types_compatible_p (orig_type, stride_type))
|
||
rhs2 = c->stride;
|
||
else
|
||
rhs2 = introduce_cast_before_cand (c, orig_type, c->stride, new_var);
|
||
|
||
stmt_to_print = replace_rhs_if_not_dup (repl_code, basis_name, rhs2,
|
||
orig_code, orig_rhs1, orig_rhs2,
|
||
c);
|
||
}
|
||
|
||
else if (double_int_minus_one_p (cand_incr))
|
||
{
|
||
tree stride_type = TREE_TYPE (c->stride);
|
||
tree orig_type = TREE_TYPE (orig_rhs2);
|
||
gcc_assert (repl_code != POINTER_PLUS_EXPR);
|
||
|
||
if (types_compatible_p (orig_type, stride_type))
|
||
rhs2 = c->stride;
|
||
else
|
||
rhs2 = introduce_cast_before_cand (c, orig_type, c->stride, new_var);
|
||
|
||
if (orig_code != MINUS_EXPR
|
||
|| !operand_equal_p (basis_name, orig_rhs1, 0)
|
||
|| !operand_equal_p (rhs2, orig_rhs2, 0))
|
||
{
|
||
gimple_stmt_iterator gsi = gsi_for_stmt (c->cand_stmt);
|
||
gimple_assign_set_rhs_with_ops (&gsi, MINUS_EXPR, basis_name, rhs2);
|
||
update_stmt (gsi_stmt (gsi));
|
||
|
||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||
stmt_to_print = gsi_stmt (gsi);
|
||
}
|
||
else if (dump_file && (dump_flags & TDF_DETAILS))
|
||
fputs (" (duplicate, not actually replacing)\n", dump_file);
|
||
}
|
||
|
||
else if (double_int_zero_p (cand_incr))
|
||
{
|
||
tree lhs = gimple_assign_lhs (c->cand_stmt);
|
||
tree lhs_type = TREE_TYPE (lhs);
|
||
tree basis_type = TREE_TYPE (basis_name);
|
||
|
||
if (types_compatible_p (lhs_type, basis_type))
|
||
{
|
||
gimple copy_stmt = gimple_build_assign (lhs, basis_name);
|
||
gimple_stmt_iterator gsi = gsi_for_stmt (c->cand_stmt);
|
||
gimple_set_location (copy_stmt, gimple_location (c->cand_stmt));
|
||
gsi_replace (&gsi, copy_stmt, false);
|
||
|
||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||
stmt_to_print = copy_stmt;
|
||
}
|
||
else
|
||
{
|
||
gimple_stmt_iterator gsi = gsi_for_stmt (c->cand_stmt);
|
||
gimple cast_stmt = gimple_build_assign_with_ops (NOP_EXPR, lhs,
|
||
basis_name,
|
||
NULL_TREE);
|
||
gimple_set_location (cast_stmt, gimple_location (c->cand_stmt));
|
||
gsi_replace (&gsi, cast_stmt, false);
|
||
|
||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||
stmt_to_print = cast_stmt;
|
||
}
|
||
}
|
||
else
|
||
gcc_unreachable ();
|
||
|
||
if (dump_file && (dump_flags & TDF_DETAILS) && stmt_to_print)
|
||
{
|
||
fputs ("With: ", dump_file);
|
||
print_gimple_stmt (dump_file, stmt_to_print, 0, 0);
|
||
fputs ("\n", dump_file);
|
||
}
|
||
}
|
||
|
||
/* For each candidate in the tree rooted at C, replace it with
|
||
an increment if such has been shown to be profitable. */
|
||
|
||
static void
|
||
replace_profitable_candidates (slsr_cand_t c)
|
||
{
|
||
if (!cand_already_replaced (c))
|
||
{
|
||
double_int increment = cand_abs_increment (c);
|
||
tree new_var = NULL;
|
||
enum tree_code orig_code = gimple_assign_rhs_code (c->cand_stmt);
|
||
unsigned i;
|
||
|
||
i = incr_vec_index (increment);
|
||
|
||
/* Only process profitable increments. Nothing useful can be done
|
||
to a cast or copy. */
|
||
if (profitable_increment_p (i)
|
||
&& orig_code != MODIFY_EXPR
|
||
&& orig_code != NOP_EXPR)
|
||
{
|
||
slsr_cand_t basis = lookup_cand (c->basis);
|
||
tree basis_name = gimple_assign_lhs (basis->cand_stmt);
|
||
replace_one_candidate (c, i, &new_var, basis_name);
|
||
}
|
||
}
|
||
|
||
if (c->sibling)
|
||
replace_profitable_candidates (lookup_cand (c->sibling));
|
||
|
||
if (c->dependent)
|
||
replace_profitable_candidates (lookup_cand (c->dependent));
|
||
}
|
||
|
||
/* Analyze costs of related candidates in the candidate vector,
|
||
and make beneficial replacements. */
|
||
|
||
static void
|
||
analyze_candidates_and_replace (void)
|
||
{
|
||
unsigned i;
|
||
slsr_cand_t c;
|
||
|
||
/* Each candidate that has a null basis and a non-null
|
||
dependent is the root of a tree of related statements.
|
||
Analyze each tree to determine a subset of those
|
||
statements that can be replaced with maximum benefit. */
|
||
FOR_EACH_VEC_ELT (slsr_cand_t, cand_vec, i, c)
|
||
{
|
||
slsr_cand_t first_dep;
|
||
|
||
if (c->basis != 0 || c->dependent == 0)
|
||
continue;
|
||
|
||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||
fprintf (dump_file, "\nProcessing dependency tree rooted at %d.\n",
|
||
c->cand_num);
|
||
|
||
first_dep = lookup_cand (c->dependent);
|
||
|
||
/* If this is a chain of CAND_REFs, unconditionally replace
|
||
each of them with a strength-reduced data reference. */
|
||
if (c->kind == CAND_REF)
|
||
replace_refs (c);
|
||
|
||
/* If the common stride of all related candidates is a
|
||
known constant, and none of these has a phi-dependence,
|
||
then all replacements are considered profitable.
|
||
Each replaces a multiply by a single add, with the
|
||
possibility that a feeding add also goes dead as a
|
||
result. */
|
||
else if (unconditional_cands_with_known_stride_p (c))
|
||
replace_dependents (first_dep);
|
||
|
||
/* When the stride is an SSA name, it may still be profitable
|
||
to replace some or all of the dependent candidates, depending
|
||
on whether the introduced increments can be reused, or are
|
||
less expensive to calculate than the replaced statements. */
|
||
else
|
||
{
|
||
unsigned length;
|
||
enum machine_mode mode;
|
||
bool speed;
|
||
|
||
/* Determine whether we'll be generating pointer arithmetic
|
||
when replacing candidates. */
|
||
address_arithmetic_p = (c->kind == CAND_ADD
|
||
&& POINTER_TYPE_P (c->cand_type));
|
||
|
||
/* If all candidates have already been replaced under other
|
||
interpretations, nothing remains to be done. */
|
||
length = count_candidates (c);
|
||
if (!length)
|
||
continue;
|
||
|
||
/* Construct an array of increments for this candidate chain. */
|
||
incr_vec = XNEWVEC (incr_info, length);
|
||
incr_vec_len = 0;
|
||
record_increments (c);
|
||
|
||
/* Determine which increments are profitable to replace. */
|
||
mode = TYPE_MODE (TREE_TYPE (gimple_assign_lhs (c->cand_stmt)));
|
||
speed = optimize_cands_for_speed_p (c);
|
||
analyze_increments (first_dep, mode, speed);
|
||
|
||
/* Insert initializers of the form T_0 = stride * increment
|
||
for use in profitable replacements. */
|
||
insert_initializers (first_dep);
|
||
dump_incr_vec ();
|
||
|
||
/* Perform the replacements. */
|
||
replace_profitable_candidates (first_dep);
|
||
free (incr_vec);
|
||
}
|
||
|
||
/* TODO: When conditional increments occur so that a
|
||
candidate is dependent upon a phi-basis, the cost of
|
||
introducing a temporary must be accounted for. */
|
||
}
|
||
}
|
||
|
||
static unsigned
|
||
execute_strength_reduction (void)
|
||
{
|
||
struct dom_walk_data walk_data;
|
||
|
||
/* Create the obstack where candidates will reside. */
|
||
gcc_obstack_init (&cand_obstack);
|
||
|
||
/* Allocate the candidate vector. */
|
||
cand_vec = VEC_alloc (slsr_cand_t, heap, 128);
|
||
|
||
/* Allocate the mapping from statements to candidate indices. */
|
||
stmt_cand_map = pointer_map_create ();
|
||
|
||
/* Create the obstack where candidate chains will reside. */
|
||
gcc_obstack_init (&chain_obstack);
|
||
|
||
/* Allocate the mapping from base expressions to candidate chains. */
|
||
base_cand_map = htab_create (500, base_cand_hash,
|
||
base_cand_eq, base_cand_free);
|
||
|
||
/* Initialize the loop optimizer. We need to detect flow across
|
||
back edges, and this gives us dominator information as well. */
|
||
loop_optimizer_init (AVOID_CFG_MODIFICATIONS);
|
||
|
||
/* Set up callbacks for the generic dominator tree walker. */
|
||
walk_data.dom_direction = CDI_DOMINATORS;
|
||
walk_data.initialize_block_local_data = NULL;
|
||
walk_data.before_dom_children = find_candidates_in_block;
|
||
walk_data.after_dom_children = NULL;
|
||
walk_data.global_data = NULL;
|
||
walk_data.block_local_data_size = 0;
|
||
init_walk_dominator_tree (&walk_data);
|
||
|
||
/* Walk the CFG in predominator order looking for strength reduction
|
||
candidates. */
|
||
walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR);
|
||
|
||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||
{
|
||
dump_cand_vec ();
|
||
dump_cand_chains ();
|
||
}
|
||
|
||
/* Analyze costs and make appropriate replacements. */
|
||
analyze_candidates_and_replace ();
|
||
|
||
/* Free resources. */
|
||
fini_walk_dominator_tree (&walk_data);
|
||
loop_optimizer_finalize ();
|
||
htab_delete (base_cand_map);
|
||
obstack_free (&chain_obstack, NULL);
|
||
pointer_map_destroy (stmt_cand_map);
|
||
VEC_free (slsr_cand_t, heap, cand_vec);
|
||
obstack_free (&cand_obstack, NULL);
|
||
|
||
return 0;
|
||
}
|
||
|
||
static bool
|
||
gate_strength_reduction (void)
|
||
{
|
||
return flag_tree_slsr;
|
||
}
|
||
|
||
struct gimple_opt_pass pass_strength_reduction =
|
||
{
|
||
{
|
||
GIMPLE_PASS,
|
||
"slsr", /* name */
|
||
gate_strength_reduction, /* gate */
|
||
execute_strength_reduction, /* execute */
|
||
NULL, /* sub */
|
||
NULL, /* next */
|
||
0, /* static_pass_number */
|
||
TV_GIMPLE_SLSR, /* tv_id */
|
||
PROP_cfg | PROP_ssa, /* properties_required */
|
||
0, /* properties_provided */
|
||
0, /* properties_destroyed */
|
||
0, /* todo_flags_start */
|
||
TODO_verify_ssa /* todo_flags_finish */
|
||
}
|
||
};
|