tree-ssa-copy.cc File Reference

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "backend.h"
#include "tree.h"
#include "gimple.h"
#include "tree-pass.h"
#include "ssa.h"
#include "gimple-pretty-print.h"
#include "fold-const.h"
#include "gimple-iterator.h"
#include "tree-cfg.h"
#include "tree-ssa-propagate.h"
#include "cfgloop.h"
#include "tree-scalar-evolution.h"
#include "tree-ssa-loop-niter.h"
#include "gimple-fold.h"

Include dependency graph for tree-ssa-copy.cc:

Data Structures
struct	prop_value_t
class	copy_prop
class	copy_folder

Functions
static bool	stmt_may_generate_copy (gimple *stmt)
static prop_value_t *	get_copy_of_val (tree var)
static tree	valueize_val (tree var)
static bool	set_copy_of_val (tree var, tree val)
static void	dump_copy_of (FILE *file, tree var)
static enum ssa_prop_result	copy_prop_visit_assignment (gimple *stmt, tree *result_p)
static enum ssa_prop_result	copy_prop_visit_cond_stmt (gimple *stmt, edge *taken_edge_p)
static void	init_copy_prop (void)
static bool	fini_copy_prop (void)
static unsigned int	execute_copy_prop (void)
gimple_opt_pass *	make_pass_copy_prop (gcc::context *ctxt)

Variables
static prop_value_t *	copy_of
static unsigned	n_copy_of

Function Documentation

copy_prop_visit_assignment()

static enum ssa_prop_result copy_prop_visit_assignment ( gimple * stmt, tree * result_p )

static

Evaluate the RHS of STMT.  If it produces a valid copy, set the LHS
value and store the LHS into *RESULT_P.   

References gimple_assign_lhs(), gimple_fold_stmt_to_constant_1(), is_gimple_min_invariant(), may_propagate_copy(), set_copy_of_val(), SSA_PROP_INTERESTING, SSA_PROP_NOT_INTERESTING, SSA_PROP_VARYING, TREE_CODE, and valueize_val().

Referenced by copy_prop::visit_stmt().

copy_prop_visit_cond_stmt()

static enum ssa_prop_result copy_prop_visit_cond_stmt ( gimple * stmt, edge * taken_edge_p )

static

Visit the GIMPLE_COND STMT.  Return SSA_PROP_INTERESTING
if it can determine which edge will be taken.  Otherwise, return
SSA_PROP_VARYING.   

References boolean_type_node, dump_file, dump_flags, find_taken_edge(), fold_binary_loc(), gimple_bb(), gimple_cond_code(), gimple_cond_lhs(), gimple_cond_rhs(), gimple_location(), print_gimple_stmt(), SSA_PROP_INTERESTING, SSA_PROP_VARYING, TDF_DETAILS, and valueize_val().

Referenced by copy_prop::visit_stmt().

dump_copy_of()

static void dump_copy_of ( FILE * file, tree var )

static

Dump the copy-of value for variable VAR to FILE.   

References copy_of, dump_flags, print_generic_expr(), SSA_NAME_VERSION, and TREE_CODE.

Referenced by copy_prop::visit_phi().

execute_copy_prop()

static unsigned int execute_copy_prop ( void )

static

Main entry point to the copy propagator.

PHIS_ONLY is true if we should only consider PHI nodes as generating
copy propagation opportunities.

The algorithm propagates the value COPY-OF using ssa_propagate.  For
every variable X_i, COPY-OF(X_i) indicates which variable is X_i created
from.  The following example shows how the algorithm proceeds at a
high level:

         1      a_24 = x_1
         2      a_2 = PHI <a_24, x_1>
         3      a_5 = PHI <a_2>
         4      x_1 = PHI <x_298, a_5, a_2>

The end result should be that a_2, a_5, a_24 and x_1 are a copy of
x_298.  Propagation proceeds as follows.

Visit #1: a_24 is copy-of x_1.  Value changed.
Visit #2: a_2 is copy-of x_1.  Value changed.
Visit #3: a_5 is copy-of x_1.  Value changed.
Visit #4: x_1 is copy-of x_298.  Value changed.
Visit #1: a_24 is copy-of x_298.  Value changed.
Visit #2: a_2 is copy-of x_298.  Value changed.
Visit #3: a_5 is copy-of x_298.  Value changed.
Visit #4: x_1 is copy-of x_298.  Stable state reached.

When visiting PHI nodes, we only consider arguments that flow
through edges marked executable by the propagation engine.  So,
when visiting statement #2 for the first time, we will only look at
the first argument (a_24) and optimistically assume that its value
is the copy of a_24 (x_1).   

References fini_copy_prop(), init_copy_prop(), ssa_propagation_engine::ssa_propagate(), and TODO_cleanup_cfg.

fini_copy_prop()

static bool fini_copy_prop ( void )

static

Deallocate memory used in copy propagation and do final
substitution.   

References cfun, changed, copy_of, FOR_EACH_SSA_NAME, free(), free_numbers_of_iterations_estimates(), i, maybe_duplicate_ssa_info_at_copy(), scev_initialized_p(), scev_reset(), substitute_and_fold_engine::substitute_and_fold(), and TREE_CODE.

Referenced by execute_copy_prop().

get_copy_of_val()

static prop_value_t * get_copy_of_val ( tree var )

inlinestatic

Return the copy-of value for VAR.   

References copy_of, NULL_TREE, SSA_NAME_DEF_STMT, SSA_NAME_VERSION, stmt_may_generate_copy(), and prop_value_t::value.

Referenced by valueize_val(), and copy_prop::visit_phi().

init_copy_prop()

static void init_copy_prop ( void )

static

Initialize structures used for copy propagation.   

References cfun, copy_of, FOR_EACH_BB_FN, FOR_EACH_SSA_TREE_OPERAND, gimple_phi_result(), gsi_end_p(), gsi_next(), gsi_start_bb(), gsi_start_phis(), gsi_stmt(), n_copy_of, num_ssa_names, prop_set_simulate_again(), prop_simulate_again_p(), set_copy_of_val(), si, SSA_OP_ALL_DEFS, stmt_ends_bb_p(), stmt_may_generate_copy(), and virtual_operand_p().

Referenced by execute_copy_prop().

make_pass_copy_prop()

gimple_opt_pass * make_pass_copy_prop

(

gcc::context *

ctxt

)

set_copy_of_val()

static bool set_copy_of_val ( tree var, tree val )

inlinestatic

Set VAL to be the copy of VAR.  If that changed return true.   

References copy_of, operand_equal_p(), and SSA_NAME_VERSION.

Referenced by copy_prop_visit_assignment(), init_copy_prop(), copy_prop::visit_phi(), and copy_prop::visit_stmt().

stmt_may_generate_copy()

static bool stmt_may_generate_copy ( gimple * stmt )

static

Return true if this statement may generate a useful copy.   

References gimple_assign_rhs1(), gimple_assign_single_p(), gimple_has_volatile_ops(), gimple_phi_result(), gimple_vuse(), is_gimple_min_invariant(), single_ssa_tree_operand(), SSA_NAME_OCCURS_IN_ABNORMAL_PHI, and SSA_OP_USE.

valueize_val()

static tree valueize_val ( tree var )

inlinestatic

Return the variable VAR is a copy of or VAR if VAR isn't the result
of a copy.   

References get_copy_of_val(), TREE_CODE, and prop_value_t::value.

Referenced by copy_prop_visit_assignment(), copy_prop_visit_cond_stmt(), and copy_prop::visit_phi().

Variable Documentation

copy_of

prop_value_t* copy_of

static

Referenced by dump_copy_of(), fini_copy_prop(), get_copy_of_val(), init_copy_prop(), set_copy_of_val(), and copy_folder::value_of_expr().

n_copy_of

unsigned n_copy_of

static

Referenced by init_copy_prop(), and copy_folder::value_of_expr().