--- /dev/null
+/*
+ * Project: libFIRM
+ * File name: ir/opt/ldstopt.c
+ * Purpose: load store optimizations
+ * Author:
+ * Created:
+ * CVS-ID: $Id$
+ * Copyright: (c) 1998-2004 Universität Karlsruhe
+ * Licence: This file protected by GPL - GNU GENERAL PUBLIC LICENSE.
+ */
+# include "irnode_t.h"
+# include "irgraph_t.h"
+# include "irmode_t.h"
+# include "iropt_t.h"
+# include "ircons_t.h"
+# include "irgmod.h"
+# include "irgwalk.h"
+# include "irvrfy.h"
+# include "tv_t.h"
+# include "dbginfo_t.h"
+# include "iropt_dbg.h"
+# include "irflag_t.h"
+# include "firmstat.h"
+
+#undef IMAX
+#define IMAX(a,b) ((a) > (b) ? (a) : (b))
+
+#define MAX_PROJ IMAX(pn_Load_max, pn_Store_max)
+
+/**
+ * walker environment
+ */
+typedef struct _walk_env_t {
+ struct obstack obst; /**< list of all stores */
+ int changes;
+} walk_env_t;
+
+/**
+ * a Load/Store info
+ */
+typedef struct _ldst_info_t {
+ ir_node *projs[MAX_PROJ]; /**< list of Proj's of this node */
+} ldst_info_t;
+
+/**
+ * walker, clears all links first
+ */
+static void init_links(ir_node *n, void *env)
+{
+ set_irn_link(n, NULL);
+}
+
+/**
+ * get the Load/Store info of a node
+ */
+static ldst_info_t *get_info(ir_node *node, walk_env_t *env)
+{
+ ldst_info_t *info = get_irn_link(node);
+
+ if (! info) {
+ info = obstack_alloc(&env->obst, sizeof(*info));
+
+ memset(info, 0, sizeof(*info));
+
+ set_irn_link(node, info);
+ }
+ return info;
+}
+
+/**
+ * update the info for a Load/Store
+ */
+static void update_projs(ldst_info_t *info, ir_node *proj)
+{
+ long nr = get_Proj_proj(proj);
+
+ assert(0 <= nr && nr <= MAX_PROJ && "Wrong proj from LoadStore");
+
+ if (info->projs[nr]) {
+ /* there is already one, do CSE */
+ exchange(proj, info->projs[nr]);
+ }
+ else
+ info->projs[nr] = proj;
+}
+
+/**
+ * walker, collects all Load/Store/Proj nodes
+ */
+static void collect_nodes(ir_node *n, void *env)
+{
+ ir_node *pred;
+ ldst_info_t *info;
+ walk_env_t *wenv = env;
+
+ if (get_irn_op(n) == op_Proj) {
+ pred = get_Proj_pred(n);
+
+ if (get_irn_op(pred) == op_Load || get_irn_op(pred) == op_Store) {
+ info = get_info(pred, wenv);
+
+ update_projs(info, n);
+ }
+ }
+}
+
+/**
+ * optimize a Load
+ */
+static int optimize_load(ir_node *load)
+{
+ ldst_info_t *info = get_irn_link(load);
+ ir_mode *load_mode = get_Load_mode(load);
+ ir_node *pred, *mem, *ptr;
+ int res = 1;
+
+ if (get_Load_volatility(load) == volatility_is_volatile)
+ return 0;
+
+ /*
+ * BEWARE: one might think that checking the modes is useless, because
+ * if the pointers are identical, they refer to the same object.
+ * This is only true in strong typed languages, not is C were the following
+ * is possible a = *(type1 *)p; b = *(type2 *)p ...
+ */
+
+ ptr = get_Load_ptr(load);
+ mem = get_Load_mem(load);
+ pred = skip_Proj(mem);
+
+ if (! info->projs[pn_Load_res] && ! info->projs[pn_Load_X_except]) {
+ /* a Load which value is neither used nor exception checked, remove it */
+ exchange(info->projs[pn_Load_M], mem);
+ res = 1;
+ }
+ else if (get_irn_op(pred) == op_Store && get_Store_ptr(pred) == ptr &&
+ get_irn_mode(get_Store_value(pred)) == load_mode) {
+ /*
+ * a load immediately after a store -- a read after write.
+ * We may remove the Load, if it does not have an exception handler
+ * OR they are in the same block. In the latter case the Load cannot
+ * throw an exception when the previous Store was quiet.
+ */
+ if (! info->projs[pn_Load_X_except] || get_nodes_block(load) == get_nodes_block(pred)) {
+ exchange( info->projs[pn_Load_res], get_Store_value(pred) );
+ exchange( info->projs[pn_Load_M], mem );
+
+ /* no exception */
+ if (info->projs[pn_Load_X_except])
+ exchange( info->projs[pn_Load_X_except], new_Bad());
+ res = 1;
+ }
+ }
+ else if (get_irn_op(pred) == op_Load && get_Load_ptr(pred) == ptr &&
+ get_Load_mode(pred) == load_mode) {
+ /*
+ * a load immediately after a load -- a read after read.
+ * We may remove the second Load, if it does not have an exception handler
+ * OR they are in the same block. In the latter case the Load cannot
+ * throw an exception when the previous Load was quiet.
+ */
+ if (! info->projs[pn_Load_X_except] || get_nodes_block(load) == get_nodes_block(pred)) {
+ ldst_info_t *pred_info = get_irn_link(pred);
+
+ if (pred_info->projs[pn_Load_res]) {
+ /* we need a data proj from the previous load for this optimization */
+ exchange( info->projs[pn_Load_res], pred_info->projs[pn_Load_res] );
+ exchange( info->projs[pn_Load_M], mem );
+ }
+ else {
+ set_Proj_pred(info->projs[pn_Load_res], pred);
+ set_nodes_block(info->projs[pn_Load_res], get_nodes_block(pred));
+ exchange( info->projs[pn_Load_M], mem );
+ }
+
+ /* no exception */
+ if (info->projs[pn_Load_X_except])
+ exchange( info->projs[pn_Load_X_except], new_Bad());
+
+ res = 1;
+ }
+ }
+ return res;
+}
+
+/**
+ * optimize a Store
+ */
+static int optimize_store(ir_node *store)
+{
+ ldst_info_t *info = get_irn_link(store);
+ ir_node *pred, *mem, *ptr, *value, *block;
+ ir_mode *mode;
+ ldst_info_t *pred_info;
+ int res = 0;
+
+ if (get_Store_volatility(store) == volatility_is_volatile)
+ return 0;
+
+ /*
+ * BEWARE: one might think that checking the modes is useless, because
+ * if the pointers are identical, they refer to the same object.
+ * This is only true in strong typed languages, not is C were the following
+ * is possible *(type1 *)p = a; *(type2 *)p = b ...
+ */
+
+ block = get_nodes_block(store);
+ ptr = get_Store_ptr(store);
+ mem = get_Store_mem(store);
+ value = get_Store_value(store);
+ pred = skip_Proj(mem);
+ mode = get_irn_mode(value);
+
+ pred_info = get_irn_link(pred);
+
+ if (get_irn_op(pred) == op_Store && get_Store_ptr(pred) == ptr &&
+ get_nodes_block(pred) == block && get_irn_mode(get_Store_value(pred)) == mode) {
+ /*
+ * a store immediately after a store in the same block -- a write after write.
+ * We may remove the first Store, if it does not have an exception handler.
+ *
+ * TODO: What, if both have the same exception handler ???
+ */
+ if (get_Store_volatility(pred) != volatility_is_volatile && !pred_info->projs[pn_Store_X_except]) {
+ exchange( pred_info->projs[pn_Store_M], get_Store_mem(pred) );
+ res = 1;
+ }
+ }
+ else if (get_irn_op(pred) == op_Load && get_Load_ptr(pred) == ptr &&
+ value == pred_info->projs[pn_Load_res]) {
+ /*
+ * a store a value immediately after a load -- a write after read.
+ * We may remove the second Store, if it does not have an exception handler.
+ */
+ if (! info->projs[pn_Store_X_except]) {
+ exchange( info->projs[pn_Store_M], mem );
+ res = 1;
+ }
+ }
+ return res;
+}
+
+/**
+ * walker, collects all Load/Store/Proj nodes
+ */
+static void do_load_store_optimize(ir_node *n, void *env)
+{
+ walk_env_t *wenv = env;
+
+ switch (get_irn_opcode(n)) {
+
+ case iro_Load:
+ wenv->changes |= optimize_load(n);
+ break;
+
+ case iro_Store:
+ wenv->changes |= optimize_store(n);
+ break;
+
+ default:
+ ;
+ }
+}
+
+/*
+ * do the load store optimization
+ */
+void optimize_load_store(ir_graph *irg)
+{
+ walk_env_t env;
+
+ assert(get_irg_phase_state(irg) != phase_building);
+
+ if (!get_opt_redundant_LoadStore())
+ return;
+
+ obstack_init(&env.obst);
+ env.changes = 0;
+
+ /* init the links, then collect Loads/Stores/Proj's in lists */
+ irg_walk_graph(irg, init_links, collect_nodes, &env);
+
+ /* now we have collected enough information, optimize */
+ irg_walk_graph(irg, NULL, do_load_store_optimize, &env);
+
+ obstack_free(&env.obst, NULL);
+
+ /* Handle graph state */
+ if (env.changes) {
+ if (get_irg_outs_state(current_ir_graph) == outs_consistent)
+ set_irg_outs_inconsistent(current_ir_graph);
+
+ /* is this really needed: Yes, as exception block may get bad but this might be tested */
+ if (get_irg_dom_state(current_ir_graph) == dom_consistent)
+ set_irg_dom_inconsistent(current_ir_graph);
+ }
+}
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