* Author:
* Created:
* CVS-ID: $Id$
- * Copyright: (c) 1998-2004 Universität Karlsruhe
+ * Copyright: (c) 1998-2004 Universit\81ät Karlsruhe
* Licence: This file protected by GPL - GNU GENERAL PUBLIC LICENSE.
*/
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#ifdef HAVE_ALLOCA_H
+#include <alloca.h>
+#endif
+#ifdef HAVE_MALLOC_H
+#include <malloc.h>
+#endif
+#ifdef HAVE_STRING_H
+# include <string.h>
+#endif
+
# include "irnode_t.h"
# include "irgraph_t.h"
# include "irmode_t.h"
# include "dbginfo_t.h"
# include "iropt_dbg.h"
# include "irflag_t.h"
-# include "firmstat.h"
+# include "array.h"
+# include "irhooks.h"
+# include "irtools.h"
+# include "opt_polymorphy.h"
+
+#ifdef DO_CACHEOPT
+#include "cacheopt/cachesim.h"
+#endif
#undef IMAX
#define IMAX(a,b) ((a) > (b) ? (a) : (b))
#define MAX_PROJ IMAX(pn_Load_max, pn_Store_max)
+enum changes_t {
+ DF_CHANGED = 1, /**< data flow changed */
+ CF_CHANGED = 2, /**< control flow changed */
+};
+
/**
* walker environment
*/
typedef struct _walk_env_t {
struct obstack obst; /**< list of all stores */
- int changes;
+ unsigned changes; /**< a bitmask of graph changes */
} walk_env_t;
+/**
+ * flags for Load/Store
+ */
+enum ldst_flags_t {
+ LDST_VISITED = 1 /**< if set, this Load/Store is already visited */
+};
+
/**
* a Load/Store info
*/
typedef struct _ldst_info_t {
- ir_node *projs[MAX_PROJ]; /**< list of Proj's of this node */
+ ir_node *projs[MAX_PROJ]; /**< list of Proj's of this node */
+ ir_node *exc_block; /**< the exception block if available */
+ int exc_idx; /**< predecessor index in the exception block */
+ unsigned flags; /**< flags */
+ unsigned visited; /**< visited counter for breaking loops */
} ldst_info_t;
/**
- * walker, clears all links first
+ * flags for control flow
*/
-static void init_links(ir_node *n, void *env)
-{
- set_irn_link(n, NULL);
-}
+enum block_flags_t {
+ BLOCK_HAS_COND = 1, /**< Block has conditional control flow */
+ BLOCK_HAS_EXC = 2 /**< Block has exceptional control flow */
+};
+
+/**
+ * a Block info
+ */
+typedef struct _block_info_t {
+ unsigned flags; /**< flags for the block */
+} block_info_t;
+
+/** the master visited flag for loop detection. */
+static unsigned master_visited = 0;
+
+#define INC_MASTER() ++master_visited
+#define MARK_NODE(info) (info)->visited = master_visited
+#define NODE_VISITED(info) (info)->visited >= master_visited
/**
* get the Load/Store info of a node
*/
-static ldst_info_t *get_info(ir_node *node, walk_env_t *env)
+static ldst_info_t *get_ldst_info(ir_node *node, walk_env_t *env)
{
ldst_info_t *info = get_irn_link(node);
}
/**
- * update the info for a Load/Store
+ * get the Block info of a node
+ */
+static block_info_t *get_block_info(ir_node *node, walk_env_t *env)
+{
+ block_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 projection info for a Load/Store
*/
-static void update_projs(ldst_info_t *info, ir_node *proj)
+static unsigned update_projs(ldst_info_t *info, ir_node *proj)
{
long nr = get_Proj_proj(proj);
if (info->projs[nr]) {
/* there is already one, do CSE */
exchange(proj, info->projs[nr]);
+ return DF_CHANGED;
}
- else
+ else {
info->projs[nr] = proj;
+ return 0;
+ }
}
+/**
+ * update the exception block info for a Load/Store node.
+ *
+ * @param info the load/store info struct
+ * @param block the exception handler block for this load/store
+ * @param pos the control flow input of the block
+ */
+static unsigned update_exc(ldst_info_t *info, ir_node *block, int pos)
+{
+ assert(info->exc_block == NULL && "more than one exception block found");
+
+ info->exc_block = block;
+ info->exc_idx = pos;
+ return 0;
+}
+
+#define get_irn_out_n(node) (unsigned)PTR_TO_INT(get_irn_link(node))
+#define set_irn_out_n(node, n) set_irn_link(adr, INT_TO_PTR(n))
+
/**
* walker, collects all Load/Store/Proj nodes
+ *
+ * walks from Start -> End
*/
-static void collect_nodes(ir_node *n, void *env)
+static void collect_nodes(ir_node *node, void *env)
{
- ir_node *pred;
- ldst_info_t *info;
+ ir_op *op = get_irn_op(node);
+ ir_node *pred, *blk, *pred_blk;
+ ldst_info_t *ldst_info;
walk_env_t *wenv = env;
- if (get_irn_op(n) == op_Proj) {
- pred = get_Proj_pred(n);
+ if (op == op_Proj) {
+ ir_node *adr;
+ ir_op *op;
+
+ pred = get_Proj_pred(node);
+ op = get_irn_op(pred);
- if (get_irn_op(pred) == op_Load || get_irn_op(pred) == op_Store) {
- info = get_info(pred, wenv);
+ if (op == op_Load) {
+ ldst_info = get_ldst_info(pred, wenv);
- update_projs(info, n);
+ wenv->changes |= update_projs(ldst_info, node);
+
+ if ((ldst_info->flags & LDST_VISITED) == 0) {
+ adr = get_Load_ptr(pred);
+ set_irn_out_n(adr, get_irn_out_n(adr) + 1);
+
+ ldst_info->flags |= LDST_VISITED;
+ }
+
+ /*
+ * Place the Proj's to the same block as the
+ * predecessor Load. This is always ok and prevents
+ * "non-SSA" form after optimizations if the Proj
+ * is in a wrong block.
+ */
+ blk = get_nodes_block(node);
+ pred_blk = get_nodes_block(pred);
+ if (blk != pred_blk) {
+ wenv->changes |= DF_CHANGED;
+ set_nodes_block(node, pred_blk);
+ }
+ }
+ else if (op == op_Store) {
+ ldst_info = get_ldst_info(pred, wenv);
+
+ wenv->changes |= update_projs(ldst_info, node);
+
+ if ((ldst_info->flags & LDST_VISITED) == 0) {
+ adr = get_Store_ptr(pred);
+ set_irn_out_n(adr, get_irn_out_n(adr) + 1);
+
+ ldst_info->flags |= LDST_VISITED;
+ }
+
+ /*
+ * Place the Proj's to the same block as the
+ * predecessor Store. This is always ok and prevents
+ * "non-SSA" form after optimizations if the Proj
+ * is in a wrong block.
+ */
+ blk = get_nodes_block(node);
+ pred_blk = get_nodes_block(pred);
+ if (blk != pred_blk) {
+ wenv->changes |= DF_CHANGED;
+ set_nodes_block(node, pred_blk);
+ }
+ }
+ }
+ else if (op == op_Block) { /* check, if it's an exception block */
+ int i;
+
+ for (i = get_Block_n_cfgpreds(node) - 1; i >= 0; --i) {
+ ir_node *pred_block;
+ block_info_t *bl_info;
+
+ pred = skip_Proj(get_Block_cfgpred(node, i));
+
+ /* ignore Bad predecessors, they will be removed later */
+ if (is_Bad(pred))
+ continue;
+
+ pred_block = get_nodes_block(pred);
+ bl_info = get_block_info(pred_block, wenv);
+
+ if (is_fragile_op(pred))
+ bl_info->flags |= BLOCK_HAS_EXC;
+ else if (is_irn_forking(pred))
+ bl_info->flags |= BLOCK_HAS_COND;
+
+ if (get_irn_op(pred) == op_Load || get_irn_op(pred) == op_Store) {
+ ldst_info = get_ldst_info(pred, wenv);
+
+ wenv->changes |= update_exc(ldst_info, node, i);
+ }
}
}
}
+/**
+ * Returns an entity if the address ptr points to a constant one.
+ */
+static entity *find_constant_entity(ir_node *ptr)
+{
+ for (;;) {
+ ir_op *op = get_irn_op(ptr);
+
+ if (op == op_SymConst && (get_SymConst_kind(ptr) == symconst_addr_ent)) {
+ return get_SymConst_entity(ptr);
+ }
+ else if (op == op_Sel) {
+ entity *ent = get_Sel_entity(ptr);
+ ir_type *tp = get_entity_owner(ent);
+
+ /* Do not fiddle with polymorphism. */
+ if (is_Class_type(get_entity_owner(ent)) &&
+ ((get_entity_n_overwrites(ent) != 0) ||
+ (get_entity_n_overwrittenby(ent) != 0) ) )
+ return NULL;
+
+ if (variability_constant == get_entity_variability(ent))
+ return ent;
+
+ if (is_Array_type(tp)) {
+ /* check bounds */
+ int i, n;
+
+ for (i = 0, n = get_Sel_n_indexs(ptr); i < n; ++i) {
+ ir_node *bound;
+ tarval *tlower, *tupper;
+ ir_node *index = get_Sel_index(ptr, i);
+ tarval *tv = computed_value(index);
+
+ /* check if the index is constant */
+ if (tv == tarval_bad)
+ return NULL;
+
+ bound = get_array_lower_bound(tp, i);
+ tlower = computed_value(bound);
+ bound = get_array_upper_bound(tp, i);
+ tupper = computed_value(bound);
+
+ if (tlower == tarval_bad || tupper == tarval_bad)
+ return NULL;
+
+ if (tarval_cmp(tv, tlower) & pn_Cmp_Lt)
+ return NULL;
+ if (tarval_cmp(tupper, tv) & pn_Cmp_Lt)
+ return NULL;
+
+ /* ok, bounds check finished */
+ }
+ }
+
+ /* try next */
+ ptr = get_Sel_ptr(ptr);
+ }
+ else
+ return NULL;
+ }
+}
+
+/**
+ * Return the Selection index of a Sel node from dimension n
+ */
+static long get_Sel_array_index_long(ir_node *n, int dim) {
+ ir_node *index = get_Sel_index(n, dim);
+ assert(get_irn_op(index) == op_Const);
+ return get_tarval_long(get_Const_tarval(index));
+}
+
+/**
+ * Returns the accessed component graph path for an
+ * node computing an address.
+ *
+ * @param ptr the node computing the address
+ * @param depth current depth in steps upward from the root
+ * of the address
+ */
+static compound_graph_path *rec_get_accessed_path(ir_node *ptr, int depth) {
+ compound_graph_path *res = NULL;
+ entity *root, *field;
+ int path_len, pos;
+
+ if (get_irn_op(ptr) == op_SymConst) {
+ /* a SymConst. If the depth is 0, this is an access to a global
+ * entity and we don't need a component path, else we know
+ * at least it's length.
+ */
+ assert(get_SymConst_kind(ptr) == symconst_addr_ent);
+ root = get_SymConst_entity(ptr);
+ res = (depth == 0) ? NULL : new_compound_graph_path(get_entity_type(root), depth);
+ }
+ else {
+ assert(get_irn_op(ptr) == op_Sel);
+ /* it's a Sel, go up until we find the root */
+ res = rec_get_accessed_path(get_Sel_ptr(ptr), depth+1);
+
+ /* fill up the step in the path at the current position */
+ field = get_Sel_entity(ptr);
+ path_len = get_compound_graph_path_length(res);
+ pos = path_len - depth - 1;
+ set_compound_graph_path_node(res, pos, field);
+
+ if (is_Array_type(get_entity_owner(field))) {
+ assert(get_Sel_n_indexs(ptr) == 1 && "multi dim arrays not implemented");
+ set_compound_graph_path_array_index(res, pos, get_Sel_array_index_long(ptr, 0));
+ }
+ }
+ return res;
+}
+
+/** Returns an access path or NULL. The access path is only
+ * valid, if the graph is in phase_high and _no_ address computation is used.
+ */
+static compound_graph_path *get_accessed_path(ir_node *ptr) {
+ return rec_get_accessed_path(ptr, 0);
+}
+
/**
* optimize a Load
*/
-static int optimize_load(ir_node *load)
+static unsigned 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;
+ ir_node *pred, *mem, *ptr, *new_node;
+ entity *ent;
+ unsigned res = 0;
+ /* do NOT touch volatile loads for now */
if (get_Load_volatility(load) == volatility_is_volatile)
return 0;
+ /* the address of the load to be optimized */
+ ptr = get_Load_ptr(load);
+
/*
- * 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 ...
+ * Check if we can remove the exception from a Load:
+ * This can be done, if the address is from an Sel(Alloc) and
+ * the Sel type is a subtype of the allocated type.
+ *
+ * This optimizes some often used OO constructs,
+ * like x = new O; x->t;
*/
+ if (info->projs[pn_Load_X_except]) {
+ if (is_Sel(ptr)) {
+ ir_node *mem = get_Sel_mem(ptr);
+
+ if (get_irn_op(skip_Proj(mem)) == op_Alloc) {
+ /* ok, check the types */
+ entity *ent = get_Sel_entity(ptr);
+ ir_type *s_type = get_entity_type(ent);
+ ir_type *a_type = get_Alloc_type(mem);
+
+ if (is_SubClass_of(s_type, a_type)) {
+ /* ok, condition met: there can't be an exception because
+ * Alloc guarantees that enough memory was allocated */
+
+ exchange(info->projs[pn_Load_X_except], new_Bad());
+ info->projs[pn_Load_X_except] = NULL;
+ res |= CF_CHANGED;
+ }
+ }
+ }
+ else if ((get_irn_op(skip_Proj(ptr)) == op_Alloc) ||
+ ((get_irn_op(ptr) == op_Cast) && (get_irn_op(skip_Proj(get_Cast_op(ptr))) == op_Alloc))) {
+ /* simple case: a direct load after an Alloc. Firm Alloc throw
+ * an exception in case of out-of-memory. So, there is no way for an
+ * exception in this load.
+ * This code is constructed by the "exception lowering" in the Jack compiler.
+ */
+ exchange(info->projs[pn_Load_X_except], new_Bad());
+ info->projs[pn_Load_X_except] = NULL;
+ res |= CF_CHANGED;
+ }
+ }
- ptr = get_Load_ptr(load);
+ /* the mem of the Load. Must still be returned after optimization */
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;
+
+ return res | DF_CHANGED;
}
- 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;
+
+ /* Load from a constant polymorphic field, where we can resolve
+ polymorphism. */
+ new_node = transform_node_Load(load);
+ if (new_node != load) {
+ if (info->projs[pn_Load_M]) {
+ exchange(info->projs[pn_Load_M], mem);
+ info->projs[pn_Load_M] = NULL;
+ }
+ if (info->projs[pn_Load_X_except]) {
+ exchange(info->projs[pn_Load_X_except], new_Bad());
+ info->projs[pn_Load_X_except] = NULL;
}
+ if (info->projs[pn_Load_res])
+ exchange(info->projs[pn_Load_res], new_node);
+ return res | DF_CHANGED;
}
- else if (get_irn_op(pred) == op_Load && get_Load_ptr(pred) == ptr &&
- get_Load_mode(pred) == load_mode) {
+
+ /* check if we can determine the entity that will be loaded */
+ ent = find_constant_entity(ptr);
+ if (ent) {
+ if ((allocation_static == get_entity_allocation(ent)) &&
+ (visibility_external_allocated != get_entity_visibility(ent))) {
+ /* a static allocation that is not external: there should be NO exception
+ * when loading. */
+
+ /* no exception, clear the info field as it might be checked later again */
+ if (info->projs[pn_Load_X_except]) {
+ exchange(info->projs[pn_Load_X_except], new_Bad());
+ info->projs[pn_Load_X_except] = NULL;
+ res |= CF_CHANGED;
+ }
+
+ if (variability_constant == get_entity_variability(ent)
+ && is_atomic_entity(ent)) {
+ /* Might not be atomic after
+ lowering of Sels. In this
+ case we could also load, but
+ it's more complicated. */
+ /* more simpler case: we load the content of a constant value:
+ * replace it by the constant itself
+ */
+
+ /* no memory */
+ if (info->projs[pn_Load_M]) {
+ exchange(info->projs[pn_Load_M], mem);
+ res |= DF_CHANGED;
+ }
+
+ /* no result :-) */
+ if (info->projs[pn_Load_res]) {
+ if (is_atomic_entity(ent)) {
+ ir_node *c = copy_const_value(get_irn_dbg_info(load), get_atomic_ent_value(ent));
+
+ DBG_OPT_RC(load, c);
+ exchange(info->projs[pn_Load_res], c);
+ return DF_CHANGED | res;
+ }
+ }
+ }
+ else if (variability_constant == get_entity_variability(ent)) {
+ compound_graph_path *path = get_accessed_path(ptr);
+
+ if (path) {
+ ir_node *c;
+
+ assert(is_proper_compound_graph_path(path, get_compound_graph_path_length(path)-1));
+ /*
+ {
+ int j;
+ for (j = 0; j < get_compound_graph_path_length(path); ++j) {
+ entity *node = get_compound_graph_path_node(path, j);
+ fprintf(stdout, ".%s", get_entity_name(node));
+ if (is_Array_type(get_entity_owner(node)))
+ fprintf(stdout, "[%d]", get_compound_graph_path_array_index(path, j));
+ }
+ printf("\n");
+ }
+ */
+
+ c = get_compound_ent_value_by_path(ent, path);
+ free_compound_graph_path(path);
+
+ /* printf(" cons: "); DDMN(c); */
+
+ if (info->projs[pn_Load_M]) {
+ exchange(info->projs[pn_Load_M], mem);
+ res |= DF_CHANGED;
+ }
+ if (info->projs[pn_Load_res]) {
+ exchange(info->projs[pn_Load_res], copy_const_value(get_irn_dbg_info(load), c));
+ return res | DF_CHANGED;
+ }
+ }
+ else {
+ /* We can not determine a correct access path. E.g., in jack, we load
+ a byte from an object to generate an exception. Happens in test program
+ Reflectiontest.
+ printf(">>>>>>>>>>>>> Found access to constant entity %s in function %s\n", get_entity_name(ent),
+ get_entity_name(get_irg_entity(current_ir_graph)));
+ printf(" load: "); DDMN(load);
+ printf(" ptr: "); DDMN(ptr);
+ */
+ }
+ }
+ }
+ }
+
+ /* Check, if the address of this load is used more than once.
+ * If not, this load cannot be removed in any case. */
+ if (get_irn_out_n(ptr) <= 1)
+ return res;
+
+ /*
+ * follow the memory chain as long as there are only Loads
+ * and try to replace current Load or Store by a previous one.
+ * Note that in unreachable loops it might happen that we reach
+ * load again, as well as we can fall into a cycle.
+ * We break such cycles using a special visited flag.
+ */
+ INC_MASTER();
+ for (pred = skip_Proj(mem); load != pred; pred = skip_Proj(get_Load_mem(pred))) {
+ ldst_info_t *pred_info = get_irn_link(pred);
+
/*
- * 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.
+ * 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 in C were the following
+ * is possible a = *(ir_type1 *)p; b = *(ir_type2 *)p ...
*/
- 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 );
+ 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 both Load & Store 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.
+ *
+ * Why we need to check for Store Exception? If the Store cannot
+ * be executed (ROM) the exception handler might simply jump into
+ * the load block :-(
+ * We could make it a little bit better if we would know that the exception
+ * handler of the Store jumps directly to the end...
+ */
+ if ((!pred_info->projs[pn_Store_X_except] && !info->projs[pn_Load_X_except]) ||
+ get_nodes_block(load) == get_nodes_block(pred)) {
+ ir_node *value = get_Store_value(pred);
+
+ DBG_OPT_RAW(load, value);
+ if (info->projs[pn_Load_M])
+ 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 |= CF_CHANGED;
+ }
+
+ if (info->projs[pn_Load_res])
+ exchange(info->projs[pn_Load_res], value);
+
+ return res | DF_CHANGED;
}
- 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 );
+ }
+ else if (get_irn_op(pred) == op_Load && get_Load_ptr(pred) == ptr &&
+ get_Load_mode(pred) == load_mode) {
+ /*
+ * a Load 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 later case the Load cannot
+ * throw an exception when the previous Load was quiet.
+ *
+ * Here, there is no need to check if the previous Load has an exception
+ * hander because they would have exact the same exception...
+ */
+ if (! info->projs[pn_Load_X_except] || get_nodes_block(load) == get_nodes_block(pred)) {
+ DBG_OPT_RAR(load, pred);
+
+ if (pred_info->projs[pn_Load_res]) {
+ /* we need a data proj from the previous load for this optimization */
+ if (info->projs[pn_Load_res])
+ exchange(info->projs[pn_Load_res], pred_info->projs[pn_Load_res]);
+
+ if (info->projs[pn_Load_M])
+ exchange(info->projs[pn_Load_M], mem);
+ }
+ else {
+ if (info->projs[pn_Load_res]) {
+ set_Proj_pred(info->projs[pn_Load_res], pred);
+ set_nodes_block(info->projs[pn_Load_res], get_nodes_block(pred));
+ pred_info->projs[pn_Load_res] = info->projs[pn_Load_res];
+ }
+ if (info->projs[pn_Load_M]) {
+ /* Actually, this if should not be necessary. Construct the Loads
+ properly!!! */
+ 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 |= CF_CHANGED;
+ }
+
+ return res |= DF_CHANGED;
}
+ }
- /* no exception */
- if (info->projs[pn_Load_X_except])
- exchange( info->projs[pn_Load_X_except], new_Bad());
+ /* follow only Load chains */
+ if (get_irn_op(pred) != op_Load)
+ break;
- res = 1;
- }
+ /* check for cycles */
+ if (NODE_VISITED(pred_info))
+ break;
+ MARK_NODE(pred_info);
}
return res;
}
/**
* optimize a Store
*/
-static int optimize_store(ir_node *store)
+static unsigned 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;
+ unsigned 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 ...
+ * is possible *(ir_type1 *)p = a; *(ir_type2 *)p = b ...
*/
- block = get_nodes_block(store);
ptr = get_Store_ptr(store);
+
+ /* Check, if the address of this load is used more than once.
+ * If not, this load cannot be removed in any case. */
+ if (get_irn_out_n(ptr) <= 1)
+ return 0;
+
+ block = get_nodes_block(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;
+ /* follow the memory chain as long as there are only Loads */
+ INC_MASTER();
+ for (pred = skip_Proj(mem); pred != store; pred = skip_Proj(get_Load_mem(pred))) {
+ ldst_info_t *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 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]) {
+ DBG_OPT_WAW(pred, store);
+ exchange( pred_info->projs[pn_Store_M], get_Store_mem(pred) );
+ return DF_CHANGED;
+ }
}
- }
- 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;
+ else if (get_irn_op(pred) == op_Load && get_Load_ptr(pred) == ptr &&
+ value == pred_info->projs[pn_Load_res]) {
+ /*
+ * a Store of a value 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]) {
+ DBG_OPT_WAR(store, pred);
+ exchange( info->projs[pn_Store_M], mem );
+ return DF_CHANGED;
+ }
}
+
+ /* follow only Load chains */
+ if (get_irn_op(pred) != op_Load)
+ break;
+
+ /* check for cycles */
+ if (NODE_VISITED(pred_info))
+ break;
+ MARK_NODE(pred_info);
}
return res;
}
/**
- * walker, collects all Load/Store/Proj nodes
+ * walker, optimizes Phi after Stores to identical places:
+ * Does the following optimization:
+ * @verbatim
+ *
+ * val1 val2 val3 val1 val2 val3
+ * | | | \ | /
+ * Str Str Str \ | /
+ * \ | / PhiData
+ * \ | / |
+ * \ | / Str
+ * PhiM
+ *
+ * @endverbatim
+ * This reduces the number of stores and allows for predicated execution.
+ * Moves Stores back to the end of a function which may be bad.
+ *
+ * This is only possible if the predecessor blocks have only one successor.
+ */
+static unsigned optimize_phi(ir_node *phi, void *env)
+{
+ walk_env_t *wenv = env;
+ int i, n;
+ ir_node *store, *old_store, *ptr, *block, *phiM, *phiD, *exc, *projM;
+ ir_mode *mode;
+ ir_node **inM, **inD;
+ int *idx;
+ dbg_info *db = NULL;
+ ldst_info_t *info;
+ block_info_t *bl_info;
+ unsigned res = 0;
+
+ /* Must be a memory Phi */
+ if (get_irn_mode(phi) != mode_M)
+ return 0;
+
+ n = get_Phi_n_preds(phi);
+ if (n <= 0)
+ return 0;
+
+ store = skip_Proj(get_Phi_pred(phi, 0));
+ old_store = store;
+ if (get_irn_op(store) != op_Store)
+ return 0;
+
+ /* abort on dead blocks */
+ if (is_Block_dead(get_nodes_block(store)))
+ return 0;
+
+ /* check if the block has only one successor */
+ bl_info = get_irn_link(get_nodes_block(store));
+ if (bl_info->flags)
+ return 0;
+
+ /* this is the address of the store */
+ ptr = get_Store_ptr(store);
+ mode = get_irn_mode(get_Store_value(store));
+ info = get_irn_link(store);
+ exc = info->exc_block;
+
+ for (i = 1; i < n; ++i) {
+ ir_node *pred = skip_Proj(get_Phi_pred(phi, i));
+
+ if (get_irn_op(pred) != op_Store)
+ return 0;
+
+ if (ptr != get_Store_ptr(pred) || mode != get_irn_mode(get_Store_value(pred)))
+ return 0;
+
+ info = get_irn_link(pred);
+
+ /* check, if all stores have the same exception flow */
+ if (exc != info->exc_block)
+ return 0;
+
+ /* abort on dead blocks */
+ if (is_Block_dead(get_nodes_block(store)))
+ return 0;
+
+ /* check if the block has only one successor */
+ bl_info = get_irn_link(get_nodes_block(store));
+ if (bl_info->flags)
+ return 0;
+ }
+
+ /*
+ * ok, when we are here, we found all predecessors of a Phi that
+ * are Stores to the same address and size. That means whatever
+ * we do before we enter the block of the Phi, we do a Store.
+ * So, we can move the Store to the current block:
+ *
+ * val1 val2 val3 val1 val2 val3
+ * | | | \ | /
+ * | Str | | Str | | Str | \ | /
+ * \ | / PhiData
+ * \ | / |
+ * \ | / Str
+ * PhiM
+ *
+ * Is only allowed if the predecessor blocks have only one successor.
+ */
+
+ /* first step: collect all inputs */
+ NEW_ARR_A(ir_node *, inM, n);
+ NEW_ARR_A(ir_node *, inD, n);
+ NEW_ARR_A(int, idx, n);
+
+ for (i = 0; i < n; ++i) {
+ ir_node *pred = skip_Proj(get_Phi_pred(phi, i));
+ info = get_irn_link(pred);
+
+ inM[i] = get_Store_mem(pred);
+ inD[i] = get_Store_value(pred);
+ idx[i] = info->exc_idx;
+ }
+ block = get_nodes_block(phi);
+
+ /* second step: create a new memory Phi */
+ phiM = new_rd_Phi(get_irn_dbg_info(phi), current_ir_graph, block, n, inM, mode_M);
+
+ /* third step: create a new data Phi */
+ phiD = new_rd_Phi(get_irn_dbg_info(phi), current_ir_graph, block, n, inD, mode);
+
+ /* fourth step: create the Store */
+ store = new_rd_Store(db, current_ir_graph, block, phiM, ptr, phiD);
+#ifdef DO_CACHEOPT
+ co_set_irn_name(store, co_get_irn_ident(old_store));
+#endif
+
+ projM = new_rd_Proj(NULL, current_ir_graph, block, store, mode_M, pn_Store_M);
+
+ info = get_ldst_info(store, wenv);
+ info->projs[pn_Store_M] = projM;
+
+ /* fifths step: repair exception flow */
+ if (exc) {
+ ir_node *projX = new_rd_Proj(NULL, current_ir_graph, block, store, mode_X, pn_Store_X_except);
+
+ info->projs[pn_Store_X_except] = projX;
+ info->exc_block = exc;
+ info->exc_idx = idx[0];
+
+ for (i = 0; i < n; ++i) {
+ set_Block_cfgpred(exc, idx[i], projX);
+ }
+
+ if (n > 1) {
+ /* the exception block should be optimized as some inputs are identical now */
+ }
+
+ res |= CF_CHANGED;
+ }
+
+ /* sixth step: replace old Phi */
+ exchange(phi, projM);
+
+ return res | DF_CHANGED;
+}
+
+/**
+ * walker, do the optimizations
*/
static void do_load_store_optimize(ir_node *n, void *env)
{
wenv->changes |= optimize_store(n);
break;
+ case iro_Phi:
+ wenv->changes |= optimize_phi(n, env);
+
default:
;
}
walk_env_t env;
assert(get_irg_phase_state(irg) != phase_building);
+ assert(get_irg_pinned(irg) != op_pin_state_floats &&
+ "LoadStore optimization needs pinned graph");
- if (!get_opt_redundant_LoadStore())
+ 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);
+ master_visited = 0;
+ irg_walk_graph(irg, firm_clear_link, collect_nodes, &env);
/* now we have collected enough information, optimize */
irg_walk_graph(irg, NULL, do_load_store_optimize, &env);
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);
+ if (env.changes & CF_CHANGED) {
+ /* is this really needed: Yes, control flow changed, block might get Bad. */
+ set_irg_doms_inconsistent(current_ir_graph);
}
}
projects / libfirm / blobdiff