/* Liveness for SSA trees.
- Copyright (C) 2003-2019 Free Software Foundation, Inc.
+ Copyright (C) 2003-2020 Free Software Foundation, Inc.
Contributed by Andrew MacLeod <amacleod@redhat.com>
This file is part of GCC.
#include "stringpool.h"
#include "attribs.h"
#include "optinfo.h"
+#include "gimple-walk.h"
+#include "cfganal.h"
static void verify_live_on_entry (tree_live_info_p);
function. */
var_map
-init_var_map (int size, struct loop *loop)
+init_var_map (int size, class loop *loop)
{
var_map map;
{
unsigned i;
tree b;
- gimple *stmt = gsi_stmt (gsi);
+ gimple *stmt;
+ next:
+ stmt = gsi_stmt (gsi);
if (!is_gimple_debug (stmt) && !gimple_clobber_p (stmt))
continue;
b = gimple_block (stmt);
if (b && !TREE_USED (b))
- gimple_set_block (stmt, NULL);
+ {
+ /* Elide debug marker stmts that have an associated BLOCK from an
+ inline instance removed with also the outermost scope BLOCK of
+ said inline instance removed. If the outermost scope BLOCK of
+ said inline instance is preserved use that in place of the
+ removed BLOCK. That keeps the marker associated to the correct
+ inline instance (or no inline instance in case it was not from
+ an inline instance). */
+ if (gimple_debug_nonbind_marker_p (stmt)
+ && BLOCK_ABSTRACT_ORIGIN (b))
+ {
+ while (TREE_CODE (b) == BLOCK
+ && !inlined_function_outer_scope_p (b))
+ b = BLOCK_SUPERCONTEXT (b);
+ if (TREE_CODE (b) == BLOCK)
+ {
+ if (TREE_USED (b))
+ {
+ gimple_set_block (stmt, b);
+ continue;
+ }
+ gsi_remove (&gsi, true);
+ if (gsi_end_p (gsi))
+ break;
+ goto next;
+ }
+ }
+ gimple_set_block (stmt, NULL);
+ }
for (i = 0; i < gimple_num_ops (stmt); i++)
walk_tree (gimple_op_ptr (stmt, i), clear_unused_block_pointer_1,
NULL, NULL);
mark_scope_block_unused (DECL_INITIAL (current_function_decl));
usedvars = BITMAP_ALLOC (NULL);
+ auto_bitmap useddebug;
/* Walk the CFG marking all referenced symbols. */
FOR_EACH_BB_FN (bb, cfun)
do it. If the block is not otherwise used, the stmt will
be cleaned up in clean_unused_block_pointer. */
if (is_gimple_debug (stmt))
- continue;
+ {
+ if (gimple_debug_bind_p (stmt))
+ {
+ tree var = gimple_debug_bind_get_var (stmt);
+ if (VAR_P (var))
+ {
+ if (!gimple_debug_bind_get_value (stmt))
+ /* Run the 2nd phase. */
+ have_local_clobbers = true;
+ else
+ bitmap_set_bit (useddebug, DECL_UID (var));
+ }
+ }
+ continue;
+ }
if (gimple_clobber_p (stmt))
{
if (b)
TREE_USED (b) = true;
}
+ else if (gimple_debug_bind_p (stmt))
+ {
+ tree var = gimple_debug_bind_get_var (stmt);
+ if (VAR_P (var)
+ && !bitmap_bit_p (useddebug, DECL_UID (var))
+ && !is_used_p (var))
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "Dead debug bind reset to %u\n",
+ DECL_UID (var));
+ gsi_remove (&gsi, true);
+ continue;
+ }
+ }
gsi_next (&gsi);
}
}
if (cfun->has_simduid_loops)
{
- struct loop *loop;
+ class loop *loop;
FOR_EACH_LOOP (loop, 0)
if (loop->simduid && !is_used_p (loop->simduid))
loop->simduid = NULL_TREE;
return live;
}
+\f
+/* Data structure for compute_live_vars* functions. */
+
+struct compute_live_vars_data {
+ /* Vector of bitmaps for live vars indices at the end of basic blocks,
+ indexed by bb->index. ACTIVE[ENTRY_BLOCK] must be empty bitmap,
+ ACTIVE[EXIT_BLOCK] is used for STOP_AFTER. */
+ vec<bitmap_head> active;
+ /* Work bitmap of currently live variables. */
+ bitmap work;
+ /* Set of interesting variables. Variables with uids not in this
+ hash_map are not tracked. */
+ live_vars_map *vars;
+};
+
+/* Callback for walk_stmt_load_store_addr_ops. If OP is a VAR_DECL with
+ uid set in DATA->vars, enter its corresponding index into bitmap
+ DATA->work. */
+
+static bool
+compute_live_vars_visit (gimple *, tree op, tree, void *pdata)
+{
+ compute_live_vars_data *data = (compute_live_vars_data *) pdata;
+ op = get_base_address (op);
+ if (op && VAR_P (op))
+ if (unsigned int *v = data->vars->get (DECL_UID (op)))
+ bitmap_set_bit (data->work, *v);
+ return false;
+}
+
+/* Helper routine for compute_live_vars, calculating the sets of live
+ variables at the end of BB, leaving the result in DATA->work.
+ If STOP_AFTER is non-NULL, stop processing after that stmt. */
+
+static void
+compute_live_vars_1 (basic_block bb, compute_live_vars_data *data,
+ gimple *stop_after)
+{
+ edge e;
+ edge_iterator ei;
+ gimple_stmt_iterator gsi;
+ walk_stmt_load_store_addr_fn visit = compute_live_vars_visit;
+
+ bitmap_clear (data->work);
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ bitmap_ior_into (data->work, &data->active[e->src->index]);
+
+ for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ walk_stmt_load_store_addr_ops (gsi_stmt (gsi), data, NULL, NULL, visit);
+ for (gsi = gsi_after_labels (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ {
+ gimple *stmt = gsi_stmt (gsi);
+
+ if (gimple_clobber_p (stmt))
+ {
+ tree lhs = gimple_assign_lhs (stmt);
+ if (VAR_P (lhs))
+ if (unsigned int *v = data->vars->get (DECL_UID (lhs)))
+ bitmap_clear_bit (data->work, *v);
+ }
+ else if (!is_gimple_debug (stmt))
+ walk_stmt_load_store_addr_ops (stmt, data, visit, visit, visit);
+ if (stmt == stop_after)
+ break;
+ }
+}
+/* For function FN and live_vars_map (hash map from DECL_UIDs to a dense set of
+ indexes of automatic variables VARS, compute which of those variables are
+ (might be) live at the end of each basic block. */
+vec<bitmap_head>
+compute_live_vars (struct function *fn, live_vars_map *vars)
+{
+ vec<bitmap_head> active;
+
+ /* We approximate the live range of a stack variable by taking the first
+ mention of its name as starting point(s), and by the end-of-scope
+ death clobber added by gimplify as ending point(s) of the range.
+ This overapproximates in the case we for instance moved an address-taken
+ operation upward, without also moving a dereference to it upwards.
+ But it's conservatively correct as a variable never can hold values
+ before its name is mentioned at least once.
+
+ We then do a mostly classical bitmap liveness algorithm. */
+
+ active.create (last_basic_block_for_fn (fn));
+ active.quick_grow (last_basic_block_for_fn (fn));
+ for (int i = 0; i < last_basic_block_for_fn (fn); i++)
+ bitmap_initialize (&active[i], &bitmap_default_obstack);
+
+ bitmap work = BITMAP_ALLOC (NULL);
+
+ int *rpo = XNEWVEC (int, last_basic_block_for_fn (fn));
+ int n_bbs = pre_and_rev_post_order_compute_fn (fn, NULL, rpo, false);
+
+ bool changed = true;
+ compute_live_vars_data data = { active, work, vars };
+ while (changed)
+ {
+ int i;
+ changed = false;
+ for (i = 0; i < n_bbs; i++)
+ {
+ basic_block bb = BASIC_BLOCK_FOR_FN (fn, rpo[i]);
+ compute_live_vars_1 (bb, &data, NULL);
+ if (bitmap_ior_into (&active[bb->index], work))
+ changed = true;
+ }
+ }
+
+ free (rpo);
+ BITMAP_FREE (work);
+
+ return active;
+}
+
+/* For ACTIVE computed by compute_live_vars, compute a bitmap of variables
+ live after the STOP_AFTER statement and return that bitmap. */
+
+bitmap
+live_vars_at_stmt (vec<bitmap_head> &active, live_vars_map *vars,
+ gimple *stop_after)
+{
+ bitmap work = BITMAP_ALLOC (NULL);
+ compute_live_vars_data data = { active, work, vars };
+ basic_block bb = gimple_bb (stop_after);
+ compute_live_vars_1 (bb, &data, stop_after);
+ return work;
+}
+
+/* Destroy what compute_live_vars has returned when it is no longer needed. */
+
+void
+destroy_live_vars (vec<bitmap_head> &active)
+{
+ unsigned len = active.length ();
+ for (unsigned i = 0; i < len; i++)
+ bitmap_clear (&active[i]);
+
+ active.release ();
+}
+\f
/* Output partition map MAP to file F. */
void
projects / gcc.git / blobdiff