/* Generic SSA value propagation engine.
- Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
+ Copyright (C) 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
Contributed by Diego Novillo <dnovillo@redhat.com>
This file is part of GCC.
#include "tree-pass.h"
#include "tree-ssa-propagate.h"
#include "langhooks.h"
-#include "varray.h"
#include "vec.h"
#include "value-prof.h"
#include "gimple.h"
/* Add a basic block to the worklist. The block must not be already
in the worklist, and it must not be the ENTRY or EXIT block. */
-static void
+static void
cfg_blocks_add (basic_block bb)
{
bool head = false;
simulate_stmt (stmt);
}
- /* We can not predict when abnormal edges will be executed, so
+ /* We can not predict when abnormal and EH edges will be executed, so
once a block is considered executable, we consider any
outgoing abnormal edges as executable.
+ TODO: This is not exactly true. Simplifying statement might
+ prove it non-throwing and also computed goto can be handled
+ when destination is known.
+
At the same time, if this block has only one successor that is
reached by non-abnormal edges, then add that successor to the
worklist. */
normal_edge = NULL;
FOR_EACH_EDGE (e, ei, block->succs)
{
- if (e->flags & EDGE_ABNORMAL)
+ if (e->flags & (EDGE_ABNORMAL | EDGE_EH))
add_control_edge (e);
else
{
edge e;
edge_iterator ei;
basic_block bb;
- size_t i;
/* Worklists of SSA edges. */
interesting_ssa_edges = VEC_alloc (gimple, gc, 20);
cfg_blocks = VEC_alloc (basic_block, heap, 20);
VEC_safe_grow (basic_block, heap, cfg_blocks, 20);
- /* Initialize the values for every SSA_NAME. */
- for (i = 1; i < num_ssa_names; i++)
- if (ssa_name (i))
- SSA_NAME_VALUE (ssa_name (i)) = NULL_TREE;
-
/* Initially assume that every edge in the CFG is not executable.
(including the edges coming out of ENTRY_BLOCK_PTR). */
FOR_ALL_BB (bb)
for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
gimple_set_plf (gsi_stmt (si), STMT_IN_SSA_EDGE_WORKLIST, false);
-
+
for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si))
gimple_set_plf (gsi_stmt (si), STMT_IN_SSA_EDGE_WORKLIST, false);
return false;
break;
- case EXC_PTR_EXPR:
- case FILTER_EXPR:
- break;
-
default:
return false;
}
{
args = VEC_alloc (tree, heap, nargs);
VEC_safe_grow (tree, heap, args, nargs);
-
+
for (i = 0; i < nargs; i++)
VEC_replace (tree, args, i, CALL_EXPR_ARG (expr, i));
}
new_stmt = gimple_build_call_vec (fn, args);
gimple_call_set_lhs (new_stmt, lhs);
- copy_virtual_operands (new_stmt, stmt);
move_ssa_defining_stmt_for_defs (new_stmt, stmt);
+ gimple_set_vuse (new_stmt, gimple_vuse (stmt));
+ gimple_set_vdef (new_stmt, gimple_vdef (stmt));
gimple_set_location (new_stmt, gimple_location (stmt));
gsi_replace (si_p, new_stmt, false);
VEC_free (tree, heap, args);
Introduce a new GIMPLE_ASSIGN statement. */
STRIP_USELESS_TYPE_CONVERSION (expr);
new_stmt = gimple_build_assign (lhs, expr);
- copy_virtual_operands (new_stmt, stmt);
move_ssa_defining_stmt_for_defs (new_stmt, stmt);
+ gimple_set_vuse (new_stmt, gimple_vuse (stmt));
+ gimple_set_vdef (new_stmt, gimple_vdef (stmt));
}
else if (!TREE_SIDE_EFFECTS (expr))
{
/* No value is expected, and EXPR has no effect.
Replace it with an empty statement. */
new_stmt = gimple_build_nop ();
+ unlink_stmt_vdef (stmt);
+ release_defs (stmt);
}
else
{
add_referenced_var (lhs);
lhs = make_ssa_name (lhs, new_stmt);
gimple_assign_set_lhs (new_stmt, lhs);
- copy_virtual_operands (new_stmt, stmt);
+ gimple_set_vuse (new_stmt, gimple_vuse (stmt));
+ gimple_set_vdef (new_stmt, gimple_vdef (stmt));
move_ssa_defining_stmt_for_defs (new_stmt, stmt);
}
gimple_set_location (new_stmt, gimple_location (stmt));
ssa_prop_init ();
/* Iterate until the worklists are empty. */
- while (!cfg_blocks_empty_p ()
+ while (!cfg_blocks_empty_p ()
|| VEC_length (gimple, interesting_ssa_edges) > 0
|| VEC_length (gimple, varying_ssa_edges) > 0)
{
}
-/* Return true if STMT is of the form 'LHS = mem_ref', where 'mem_ref'
- is a non-volatile pointer dereference, a structure reference or a
- reference to a single _DECL. Ignore volatile memory references
- because they are not interesting for the optimizers. */
-
-bool
-stmt_makes_single_load (gimple stmt)
-{
- tree rhs;
-
- if (gimple_code (stmt) != GIMPLE_ASSIGN)
- return false;
-
- /* Only a GIMPLE_SINGLE_RHS assignment may have a
- declaration or reference as its RHS. */
- if (get_gimple_rhs_class (gimple_assign_rhs_code (stmt))
- != GIMPLE_SINGLE_RHS)
- return false;
-
- if (ZERO_SSA_OPERANDS (stmt, SSA_OP_VDEF|SSA_OP_VUSE))
- return false;
-
- rhs = gimple_assign_rhs1 (stmt);
-
- return (!TREE_THIS_VOLATILE (rhs)
- && (DECL_P (rhs)
- || REFERENCE_CLASS_P (rhs)));
-}
-
-
/* Return true if STMT is of the form 'mem_ref = RHS', where 'mem_ref'
is a non-volatile pointer dereference, a structure reference or a
reference to a single _DECL. Ignore volatile memory references
&& gimple_code (stmt) != GIMPLE_CALL)
return false;
- if (ZERO_SSA_OPERANDS (stmt, SSA_OP_VDEF))
+ if (!gimple_vdef (stmt))
return false;
lhs = gimple_get_lhs (stmt);
{
long num_const_prop;
long num_copy_prop;
- long num_pred_folded;
+ long num_stmts_folded;
long num_dce;
};
}
}
}
-
+
if (dump_file && (dump_flags & TDF_DETAILS))
{
if (!replaced)
}
-/* If the statement pointed by SI has a predicate whose value can be
- computed using the value range information computed by VRP, compute
- its value and return true. Otherwise, return false. */
-
-static bool
-fold_predicate_in (gimple_stmt_iterator *si)
-{
- bool assignment_p = false;
- tree val;
- gimple stmt = gsi_stmt (*si);
-
- if (is_gimple_assign (stmt)
- && TREE_CODE_CLASS (gimple_assign_rhs_code (stmt)) == tcc_comparison)
- {
- assignment_p = true;
- val = vrp_evaluate_conditional (gimple_assign_rhs_code (stmt),
- gimple_assign_rhs1 (stmt),
- gimple_assign_rhs2 (stmt),
- stmt);
- }
- else if (gimple_code (stmt) == GIMPLE_COND)
- val = vrp_evaluate_conditional (gimple_cond_code (stmt),
- gimple_cond_lhs (stmt),
- gimple_cond_rhs (stmt),
- stmt);
- else
- return false;
-
-
- if (val)
- {
- if (assignment_p)
- val = fold_convert (gimple_expr_type (stmt), val);
-
- if (dump_file)
- {
- fprintf (dump_file, "Folding predicate ");
- print_gimple_expr (dump_file, stmt, 0, 0);
- fprintf (dump_file, " to ");
- print_generic_expr (dump_file, val, 0);
- fprintf (dump_file, "\n");
- }
-
- prop_stats.num_pred_folded++;
-
- if (is_gimple_assign (stmt))
- gimple_assign_set_rhs_from_tree (si, val);
- else
- {
- gcc_assert (gimple_code (stmt) == GIMPLE_COND);
- if (integer_zerop (val))
- gimple_cond_make_false (stmt);
- else if (integer_onep (val))
- gimple_cond_make_true (stmt);
- else
- gcc_unreachable ();
- }
-
- return true;
- }
-
- return false;
-}
-
-
/* Perform final substitution and folding of propagated values.
PROP_VALUE[I] contains the single value that should be substituted
at every use of SSA name N_I. If PROP_VALUE is NULL, no values are
substituted.
- If USE_RANGES_P is true, statements that contain predicate
- expressions are evaluated with a call to vrp_evaluate_conditional.
- This will only give meaningful results when called from tree-vrp.c
- (the information used by vrp_evaluate_conditional is built by the
- VRP pass).
+ If FOLD_FN is non-NULL the function will be invoked on all statements
+ before propagating values for pass specific simplification.
Return TRUE when something changed. */
bool
-substitute_and_fold (prop_value_t *prop_value, bool use_ranges_p)
+substitute_and_fold (prop_value_t *prop_value, ssa_prop_fold_stmt_fn fold_fn)
{
basic_block bb;
bool something_changed = false;
- if (prop_value == NULL && !use_ranges_p)
+ if (prop_value == NULL && !fold_fn)
return false;
if (dump_file && (dump_flags & TDF_DETAILS))
{
bool did_replace;
gimple stmt = gsi_stmt (i);
+ gimple old_stmt;
enum gimple_code code = gimple_code (stmt);
+ gimple_stmt_iterator oldi;
+
+ oldi = i;
+ gsi_prev (&i);
/* Ignore ASSERT_EXPRs. They are used by VRP to generate
range information for names and they are discarded
if (code == GIMPLE_ASSIGN
&& TREE_CODE (gimple_assign_rhs1 (stmt)) == ASSERT_EXPR)
- {
- gsi_prev (&i);
- continue;
- }
+ continue;
/* No point propagating into a stmt whose result is not used,
but instead we might be able to remove a trivially dead stmt. */
fprintf (dump_file, "\n");
}
prop_stats.num_dce++;
- gsi_prev (&i);
i2 = gsi_for_stmt (stmt);
gsi_remove (&i2, true);
release_defs (stmt);
continue;
}
- /* Record the state of the statement before replacements. */
- push_stmt_changes (gsi_stmt_ptr (&i));
-
/* Replace the statement with its folded version and mark it
folded. */
did_replace = false;
print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
}
- /* If we have range information, see if we can fold
- predicate expressions. */
- if (use_ranges_p)
+ old_stmt = stmt;
+
+ /* Some statements may be simplified using propagator
+ specific information. Do this before propagating
+ into the stmt to not disturb pass specific information. */
+ if (fold_fn
+ && (*fold_fn)(&oldi))
{
- did_replace = fold_predicate_in (&i);
- /* fold_predicate_in should not have reallocated STMT. */
- gcc_assert (gsi_stmt (i) == stmt);
+ did_replace = true;
+ prop_stats.num_stmts_folded++;
}
/* Only replace real uses if we couldn't fold the
&& !did_replace)
did_replace |= replace_uses_in (stmt, prop_value);
- /* If we made a replacement, fold and cleanup the statement. */
+ /* If we made a replacement, fold the statement. */
if (did_replace)
- {
- gimple old_stmt = stmt;
+ fold_stmt (&oldi);
- fold_stmt (&i);
- stmt = gsi_stmt (i);
+ /* Now cleanup. */
+ if (did_replace)
+ {
+ stmt = gsi_stmt (oldi);
/* If we cleaned up EH information from the statement,
remove EH edges. */
== GIMPLE_SINGLE_RHS))
{
tree rhs = gimple_assign_rhs1 (stmt);
-
+
if (TREE_CODE (rhs) == ADDR_EXPR)
recompute_tree_invariant_for_addr_expr (rhs);
}
/* Determine what needs to be done to update the SSA form. */
- pop_stmt_changes (gsi_stmt_ptr (&i));
- something_changed = true;
- }
- else
- {
- /* The statement was not modified, discard the change buffer. */
- discard_stmt_changes (gsi_stmt_ptr (&i));
+ update_stmt (stmt);
+ if (!is_gimple_debug (stmt))
+ something_changed = true;
}
if (dump_file && (dump_flags & TDF_DETAILS))
else
fprintf (dump_file, "Not folded\n");
}
-
- /* Some statements may be simplified using ranges. For
- example, division may be replaced by shifts, modulo
- replaced with bitwise and, etc. Do this after
- substituting constants, folding, etc so that we're
- presented with a fully propagated, canonicalized
- statement. */
- if (use_ranges_p)
- simplify_stmt_using_ranges (stmt);
-
- gsi_prev (&i);
}
}
prop_stats.num_const_prop);
statistics_counter_event (cfun, "Copies propagated",
prop_stats.num_copy_prop);
- statistics_counter_event (cfun, "Predicates folded",
- prop_stats.num_pred_folded);
+ statistics_counter_event (cfun, "Statements folded",
+ prop_stats.num_stmts_folded);
statistics_counter_event (cfun, "Statements deleted",
prop_stats.num_dce);
return something_changed;
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