#include "tm_p.h"
#include "basic-block.h"
#include "timevar.h"
-#include "diagnostic.h"
+#include "gimple-pretty-print.h"
#include "tree-flow.h"
#include "tree-pass.h"
#include "tree-dump.h"
the CFG. */
-struct dse_global_data
-{
- /* This is the global bitmap for store statements.
-
- Each statement has a unique ID. When we encounter a store statement
- that we want to record, set the bit corresponding to the statement's
- unique ID in this bitmap. */
- bitmap stores;
-};
-
-/* We allocate a bitmap-per-block for stores which are encountered
- during the scan of that block. This allows us to restore the
- global bitmap of stores when we finish processing a block. */
-struct dse_block_local_data
-{
- bitmap stores;
-};
+/* Bitmap of blocks that have had EH statements cleaned. We should
+ remove their dead edges eventually. */
+static bitmap need_eh_cleanup;
static bool gate_dse (void);
static unsigned int tree_ssa_dse (void);
-static void dse_initialize_block_local_data (struct dom_walk_data *,
- basic_block,
- bool);
static void dse_enter_block (struct dom_walk_data *, basic_block);
-static void dse_leave_block (struct dom_walk_data *, basic_block);
-static void record_voperand_set (bitmap, bitmap *, unsigned int);
-
-/* Returns uid of statement STMT. */
-
-static unsigned
-get_stmt_uid (gimple stmt)
-{
- if (gimple_code (stmt) == GIMPLE_PHI)
- return SSA_NAME_VERSION (gimple_phi_result (stmt))
- + gimple_stmt_max_uid (cfun);
-
- return gimple_uid (stmt);
-}
-
-/* Set bit UID in bitmaps GLOBAL and *LOCAL, creating *LOCAL as needed. */
-
-static void
-record_voperand_set (bitmap global, bitmap *local, unsigned int uid)
-{
- /* Lazily allocate the bitmap. Note that we do not get a notification
- when the block local data structures die, so we allocate the local
- bitmap backed by the GC system. */
- if (*local == NULL)
- *local = BITMAP_GGC_ALLOC ();
-
- /* Set the bit in the local and global bitmaps. */
- bitmap_set_bit (*local, uid);
- bitmap_set_bit (global, uid);
-}
-/* Initialize block local data structures. */
-
-static void
-dse_initialize_block_local_data (struct dom_walk_data *walk_data,
- basic_block bb ATTRIBUTE_UNUSED,
- bool recycled)
-{
- struct dse_block_local_data *bd
- = (struct dse_block_local_data *)
- VEC_last (void_p, walk_data->block_data_stack);
-
- /* If we are given a recycled block local data structure, ensure any
- bitmap associated with the block is cleared. */
- if (recycled)
- {
- if (bd->stores)
- bitmap_clear (bd->stores);
- }
-}
/* A helper of dse_optimize_stmt.
Given a GIMPLE_ASSIGN in STMT, find a candidate statement *USE_STMT that
continue walking until both stores have equal reference trees. */
while (!stmt_may_clobber_ref_p (temp, gimple_assign_lhs (stmt)));
- if (!is_gimple_assign (temp))
- return false;
-
*use_stmt = temp;
return true;
post dominates the first store, then the first store is dead. */
static void
-dse_optimize_stmt (struct dse_global_data *dse_gd,
- struct dse_block_local_data *bd,
- gimple_stmt_iterator gsi)
+dse_optimize_stmt (gimple_stmt_iterator gsi)
{
gimple stmt = gsi_stmt (gsi);
{
gimple use_stmt;
- record_voperand_set (dse_gd->stores, &bd->stores, gimple_uid (stmt));
-
if (!dse_possible_dead_store_p (stmt, &use_stmt))
return;
stores are to the same memory location or there is a chain of
virtual uses from stmt and the stmt which stores to that same
memory location, then we may have found redundant store. */
- if (bitmap_bit_p (dse_gd->stores, get_stmt_uid (use_stmt))
- && operand_equal_p (gimple_assign_lhs (stmt),
- gimple_assign_lhs (use_stmt), 0))
+ if ((gimple_has_lhs (use_stmt)
+ && (operand_equal_p (gimple_assign_lhs (stmt),
+ gimple_get_lhs (use_stmt), 0)))
+ || stmt_kills_ref_p (use_stmt, gimple_assign_lhs (stmt)))
{
/* If use_stmt is or might be a nop assignment, e.g. for
struct { ... } S a, b, *p; ...
acts as a use as well as definition, so store in STMT
is not dead. */
if (stmt != use_stmt
- && !is_gimple_reg (gimple_assign_rhs1 (use_stmt))
- && !is_gimple_min_invariant (gimple_assign_rhs1 (use_stmt))
- /* ??? Should {} be invariant? */
- && gimple_assign_rhs_code (use_stmt) != CONSTRUCTOR
- && refs_may_alias_p (gimple_assign_lhs (use_stmt),
- gimple_assign_rhs1 (use_stmt)))
+ && ref_maybe_used_by_stmt_p (use_stmt, gimple_assign_lhs (stmt)))
return;
if (dump_file && (dump_flags & TDF_DETAILS))
/* Then we need to fix the operand of the consuming stmt. */
unlink_stmt_vdef (stmt);
+ bitmap_set_bit (need_eh_cleanup, gimple_bb (stmt)->index);
+
/* Remove the dead store. */
gsi_remove (&gsi, true);
}
}
-/* Record that we have seen the PHIs at the start of BB which correspond
- to virtual operands. */
-static void
-dse_record_phi (struct dse_global_data *dse_gd,
- struct dse_block_local_data *bd,
- gimple phi)
-{
- if (!is_gimple_reg (gimple_phi_result (phi)))
- record_voperand_set (dse_gd->stores, &bd->stores, get_stmt_uid (phi));
-}
-
static void
-dse_enter_block (struct dom_walk_data *walk_data, basic_block bb)
+dse_enter_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb)
{
- struct dse_block_local_data *bd
- = (struct dse_block_local_data *)
- VEC_last (void_p, walk_data->block_data_stack);
- struct dse_global_data *dse_gd
- = (struct dse_global_data *) walk_data->global_data;
gimple_stmt_iterator gsi;
for (gsi = gsi_last (bb_seq (bb)); !gsi_end_p (gsi); gsi_prev (&gsi))
- dse_optimize_stmt (dse_gd, bd, gsi);
- for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
- dse_record_phi (dse_gd, bd, gsi_stmt (gsi));
-}
-
-static void
-dse_leave_block (struct dom_walk_data *walk_data,
- basic_block bb ATTRIBUTE_UNUSED)
-{
- struct dse_block_local_data *bd
- = (struct dse_block_local_data *)
- VEC_last (void_p, walk_data->block_data_stack);
- struct dse_global_data *dse_gd
- = (struct dse_global_data *) walk_data->global_data;
- bitmap stores = dse_gd->stores;
- unsigned int i;
- bitmap_iterator bi;
-
- /* Unwind the stores noted in this basic block. */
- if (bd->stores)
- EXECUTE_IF_SET_IN_BITMAP (bd->stores, 0, i, bi)
- {
- bitmap_clear_bit (stores, i);
- }
+ dse_optimize_stmt (gsi);
}
/* Main entry point. */
tree_ssa_dse (void)
{
struct dom_walk_data walk_data;
- struct dse_global_data dse_gd;
+
+ need_eh_cleanup = BITMAP_ALLOC (NULL);
renumber_gimple_stmt_uids ();
/* Dead store elimination is fundamentally a walk of the post-dominator
tree and a backwards walk of statements within each block. */
walk_data.dom_direction = CDI_POST_DOMINATORS;
- walk_data.initialize_block_local_data = dse_initialize_block_local_data;
+ walk_data.initialize_block_local_data = NULL;
walk_data.before_dom_children = dse_enter_block;
- walk_data.after_dom_children = dse_leave_block;
+ walk_data.after_dom_children = NULL;
- walk_data.block_local_data_size = sizeof (struct dse_block_local_data);
-
- /* This is the main hash table for the dead store elimination pass. */
- dse_gd.stores = BITMAP_ALLOC (NULL);
- walk_data.global_data = &dse_gd;
+ walk_data.block_local_data_size = 0;
+ walk_data.global_data = NULL;
/* Initialize the dominator walker. */
init_walk_dominator_tree (&walk_data);
/* Finalize the dominator walker. */
fini_walk_dominator_tree (&walk_data);
- /* Release the main bitmap. */
- BITMAP_FREE (dse_gd.stores);
+ /* Removal of stores may make some EH edges dead. Purge such edges from
+ the CFG as needed. */
+ if (!bitmap_empty_p (need_eh_cleanup))
+ {
+ gimple_purge_all_dead_eh_edges (need_eh_cleanup);
+ cleanup_tree_cfg ();
+ }
+ BITMAP_FREE (need_eh_cleanup);
+
/* For now, just wipe the post-dominator information. */
free_dominance_info (CDI_POST_DOMINATORS);
return 0;
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
- TODO_dump_func
- | TODO_ggc_collect
+ TODO_ggc_collect
| TODO_verify_ssa /* todo_flags_finish */
}
};
-
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