* Project: libFIRM
* File name: ir/opt/ldstopt.c
* Purpose: load store optimizations
- * Author:
+ * Author: Michael Beck
* Created:
* CVS-ID: $Id$
* Copyright: (c) 1998-2004 Universit\81ät Karlsruhe
# include <string.h>
#endif
-# 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 "array.h"
-# include "firmstat.h"
+#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 "array.h"
+#include "irhooks.h"
+#include "iredges.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;
+ struct obstack obst; /**< list of all stores */
+ unsigned changes; /**< a bitmask of graph changes */
} walk_env_t;
/**
LDST_VISITED = 1 /**< if set, this Load/Store is already visited */
};
-/**
- * a Load/Store info
- */
+/** A Load/Store info. */
typedef struct _ldst_info_t {
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;
/**
- * flags for control flow
+ * flags for control flow.
*/
enum block_flags_t {
BLOCK_HAS_COND = 1, /**< Block has conditional control flow */
- BLOCK_HAS_EXC = 2 /**< Block has exceptionl control flow */
+ BLOCK_HAS_EXC = 2 /**< Block has exceptional control flow */
};
/**
- * a Block info
+ * a Block info.
*/
typedef struct _block_info_t {
unsigned flags; /**< flags for the block */
} block_info_t;
-/**
- * walker, clears all links first
- */
-static void init_links(ir_node *n, void *env)
-{
- set_irn_link(n, NULL);
-}
+/** 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_ldst_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);
if (! info) {
/**
* update the projection info for a Load/Store
*/
-static int 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 1;
+ return DF_CHANGED;
}
else {
info->projs[nr] = proj;
}
/**
- * update the exception block info for a Load/Store
+ * 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 int update_exc(ldst_info_t *info, ir_node *block, int pos)
+static unsigned update_exc(ldst_info_t *info, ir_node *block, int pos)
{
assert(info->exc_block == NULL && "more than one exception block found");
return 0;
}
-#define get_irn_out_n(node) (unsigned)get_irn_link(node)
-#define set_irn_out_n(node, n) set_irn_link(adr, (void *)(n))
+/** Return the number of uses of an address node */
+#define get_irn_n_uses(adr) get_irn_n_edges(adr)
/**
* walker, collects all Load/Store/Proj nodes
*
- * walks form Start -> End
+ * walks from Start -> End
*/
static void collect_nodes(ir_node *node, void *env)
{
ir_op *op = get_irn_op(node);
- ir_node *pred;
+ ir_node *pred, *blk, *pred_blk;
ldst_info_t *ldst_info;
walk_env_t *wenv = env;
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);
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, n;
+ else if (op == op_Block) {
+ int i;
- for (i = 0, n = get_Block_n_cfgpreds(node); i < n; ++i) {
+ for (i = get_Block_n_cfgpreds(node) - 1; i >= 0; --i) {
ir_node *pred_block;
block_info_t *bl_info;
/* ignore Bad predecessors, they will be removed later */
if (is_Bad(pred))
- continue;
+ 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_forking_op(pred))
- bl_info->flags |= BLOCK_HAS_COND;
+ 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);
}
/**
- * returns a entity if the address ptr points to a constant one.
+ * Returns an entity if the address ptr points to a constant one.
*/
-static entity *find_constant_entity(ir_node *ptr)
+static ir_entity *find_constant_entity(ir_node *ptr)
{
for (;;) {
ir_op *op = get_irn_op(ptr);
return get_SymConst_entity(ptr);
}
else if (op == op_Sel) {
- entity *ent = get_Sel_entity(ptr);
- type *tp = get_entity_owner(ent);
+ ir_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 */
if (tlower == tarval_bad || tupper == tarval_bad)
return NULL;
- if (tarval_cmp(tv, tlower) & Lt)
+ if (tarval_cmp(tv, tlower) & pn_Cmp_Lt)
return NULL;
- if (tarval_cmp(tupper, tv) & Lt)
+ if (tarval_cmp(tupper, tv) & pn_Cmp_Lt)
return NULL;
/* ok, bounds check finished */
}
/**
- * optimize a Load
+ * Return the Selection index of a Sel node from dimension n
*/
-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;
- entity *ent;
- int res = 0;
-
- /* the address of the load to be optimized */
- ptr = get_Load_ptr(load);
+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));
+}
- /*
- * Check if we can remove the exception form a Load:
- * this can be done, if the address is from an Sel(Alloc) and
- * the Sel type is a subtype of the alloc type.
- *
- * This optimizes some often used OO constructs,
- * like x = new O; x->t;
- */
- if (info->projs[pn_Load_X_except]) {
- if (get_irn_op(ptr) == op_Sel) {
- ir_node *mem = get_Sel_mem(ptr);
+/**
+ * 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;
+ ir_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;
+}
- if (get_irn_op(mem) == op_Alloc) {
- /* ok, check the types */
- entity *ent = get_Sel_entity(ptr);
- type *s_type = get_entity_type(ent);
- type *a_type = get_Alloc_type(mem);
+/** 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);
+}
- 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 */
+/* forward */
+static void reduce_adr_usage(ir_node *ptr);
- exchange(info->projs[pn_Load_X_except], new_Bad());
- info->projs[pn_Load_X_except] = NULL;
- }
- }
- }
- else if (get_irn_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;
- }
- }
+/**
+ * Update a Load that may lost it's usage.
+ */
+static void handle_load_update(ir_node *load) {
+ ldst_info_t *info = get_irn_link(load);
/* do NOT touch volatile loads for now */
if (get_Load_volatility(load) == volatility_is_volatile)
- return 0;
+ return;
if (! info->projs[pn_Load_res] && ! info->projs[pn_Load_X_except]) {
+ ir_node *ptr = get_Load_ptr(load);
+ ir_node *mem = get_Load_mem(load);
+
/* a Load which value is neither used nor exception checked, remove it */
- mem = get_Load_mem(load);
exchange(info->projs[pn_Load_M], mem);
-
- return 1;
+ exchange(load, new_Bad());
+ reduce_adr_usage(ptr);
}
+}
- /* the mem of the Load. Must still be returned after optimization */
- mem = get_Load_mem(load);
-
- /* 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;
- }
-
- 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);
-
- /* no result :-) */
- if (info->projs[pn_Load_res]) {
- if (is_atomic_entity(ent)) {
- ir_node *c = copy_const_value(get_atomic_ent_value(ent));
-
- DBG_OPT_RC(load, c);
- exchange(info->projs[pn_Load_res], c);
-
- return 1;
- }
- }
- }
- else if (variability_constant == get_entity_variability(ent)) {
- printf(">>>>>>>>>>>>> Found access to constant entity %s in function %s\n", get_entity_name(ent),
- get_entity_name(get_irg_entity(current_ir_graph)));
+/**
+ * A Use of an address node is vanished. Check if this was a Proj
+ * node and update the counters.
+ */
+static void reduce_adr_usage(ir_node *ptr) {
+ if (is_Proj(ptr)) {
+ if (get_irn_n_edges(ptr) <= 0) {
+ /* this Proj is dead now */
+ ir_node *pred = get_Proj_pred(ptr);
+ opcode code = get_irn_opcode(pred);
+
+ if (code == iro_Load) {
+ ldst_info_t *info = get_irn_link(pred);
+ info->projs[get_Proj_proj(ptr)] = NULL;
+
+ /* this node lost it's result proj, handle that */
+ handle_load_update(pred);
}
-
- /* we changed the irg, but try further */
- res = 1;
}
}
+}
- /* 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;
+/**
+ * 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() must be called before dive into
+ */
+static unsigned follow_Load_chain(ir_node *load, ir_node *curr) {
+ unsigned res = 0;
+ ldst_info_t *info = get_irn_link(load);
+ ir_node *pred;
+ ir_node *ptr = get_Load_ptr(load);
+ ir_node *mem = get_Load_mem(load);
+ ir_mode *load_mode = get_Load_mode(load);
- /* follow the memory chain as long as there are only Loads */
- for (pred = skip_Proj(mem); ; pred = skip_Proj(get_Load_mem(pred))) {
+ for (pred = curr; load != pred; pred = skip_Proj(get_Load_mem(pred))) {
+ ldst_info_t *pred_info = get_irn_link(pred);
/*
* 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 ...
+ * 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 (get_irn_op(pred) == op_Store && get_Store_ptr(pred) == ptr &&
get_irn_mode(get_Store_value(pred)) == load_mode) {
- ldst_info_t *pred_info = get_irn_link(pred);
-
/*
* 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 Exc? If the Store cannot be executed (ROM)
- * the exception handler might simply jump into the load block :-(
+ * 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)) {
- DBG_OPT_RAW(load, pred);
- exchange( info->projs[pn_Load_res], get_Store_value(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])
+ if (info->projs[pn_Load_X_except]) {
exchange( info->projs[pn_Load_X_except], new_Bad());
- return 1;
+ res |= CF_CHANGED;
+ }
+
+ if (info->projs[pn_Load_res])
+ exchange(info->projs[pn_Load_res], value);
+
+ exchange(load, new_Bad());
+ reduce_adr_usage(ptr);
+ return res | DF_CHANGED;
}
}
else if (get_irn_op(pred) == op_Load && get_Load_ptr(pred) == ptr &&
* 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 previos Load has an exception hander because
- * they would have exact the same exception...
+ * 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)) {
- ldst_info_t *pred_info = get_irn_link(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 */
- exchange( info->projs[pn_Load_res], pred_info->projs[pn_Load_res] );
+ 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);
}
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
}
/* no exception */
- if (info->projs[pn_Load_X_except])
+ if (info->projs[pn_Load_X_except]) {
exchange(info->projs[pn_Load_X_except], new_Bad());
+ res |= CF_CHANGED;
+ }
- return 1;
+ exchange(load, new_Bad());
+ reduce_adr_usage(ptr);
+ return res |= 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);
+ }
+
+ if (get_irn_op(pred) == op_Sync) {
+ int i;
+
+ /* handle all Sync predecessors */
+ for (i = get_Sync_n_preds(pred) - 1; i >= 0; --i) {
+ res |= follow_Load_chain(load, skip_Proj(get_Sync_pred(pred, i)));
+ if (res)
+ break;
+ }
+ }
+
return res;
}
/**
- * optimize a Store
+ * optimize a Load
*/
-static int optimize_store(ir_node *store)
+static unsigned optimize_load(ir_node *load)
{
- ldst_info_t *info = get_irn_link(store);
- ir_node *pred, *mem, *ptr, *value, *block;
- ir_mode *mode;
- int res = 0;
+ ldst_info_t *info = get_irn_link(load);
+ ir_node *mem, *ptr, *new_node;
+ ir_entity *ent;
+ unsigned res = 0;
- if (get_Store_volatility(store) == volatility_is_volatile)
+ /* 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 *(type1 *)p = a; *(type2 *)p = b ...
+ * 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 */
+ ir_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;
+ }
+ }
+
+ /* the mem of the Load. Must still be returned after optimization */
+ mem = get_Load_mem(load);
+
+ 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);
+
+ exchange(load, new_Bad());
+ reduce_adr_usage(ptr);
+ return res | DF_CHANGED;
+ }
+
+ /* 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);
- ptr = get_Store_ptr(store);
+ exchange(load, new_Bad());
+ reduce_adr_usage(ptr);
+ return res | DF_CHANGED;
+ }
+
+ /* 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);
+ res |= DF_CHANGED;
+ }
+ }
+ exchange(load, new_Bad());
+ reduce_adr_usage(ptr);
+ return 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) {
+ ir_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));
+ res |= DF_CHANGED;
+ }
+ exchange(load, new_Bad());
+ reduce_adr_usage(ptr);
+ return res;
+ }
+ 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 0;
+ if (get_irn_n_uses(ptr) <= 1)
+ return res;
- block = get_nodes_block(store);
- mem = get_Store_mem(store);
- value = get_Store_value(store);
- mode = get_irn_mode(value);
+ /*
+ * 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();
+ res = follow_Load_chain(load, skip_Proj(mem));
+ return res;
+}
- /* follow the memory chain as long as there are only Loads */
- for (pred = skip_Proj(mem); ; pred = skip_Proj(get_Load_mem(pred))) {
+/**
+ * follow the memory chain as long as there are only Loads.
+ *
+ * INC_MASTER() must be called before dive into
+ */
+static unsigned follow_Load_chain_for_Store(ir_node *store, ir_node *curr) {
+ unsigned res = 0;
+ ldst_info_t *info = get_irn_link(store);
+ ir_node *pred;
+ ir_node *ptr = get_Store_ptr(store);
+ ir_node *mem = get_Store_mem(store);
+ ir_node *value = get_Store_value(store);
+ ir_mode *mode = get_irn_mode(value);
+ ir_node *block = get_nodes_block(store);
+
+ for (pred = curr; pred != store; pred = skip_Proj(get_Load_mem(pred))) {
ldst_info_t *pred_info = get_irn_link(pred);
+ /*
+ * 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 *(ir_type1 *)p = a; *(ir_type2 *)p = b ...
+ */
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) {
/*
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 1;
+ exchange(pred, new_Bad());
+ reduce_adr_usage(ptr);
+ return DF_CHANGED;
}
}
else if (get_irn_op(pred) == op_Load && get_Load_ptr(pred) == ptr &&
if (! info->projs[pn_Store_X_except]) {
DBG_OPT_WAR(store, pred);
exchange( info->projs[pn_Store_M], mem );
- return 1;
+ exchange(store, new_Bad());
+ reduce_adr_usage(ptr);
+ 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);
+ }
+
+ if (get_irn_op(pred) == op_Sync) {
+ int i;
+
+ /* handle all Sync predecessors */
+ for (i = get_Sync_n_preds(pred) - 1; i >= 0; --i) {
+ res |= follow_Load_chain_for_Store(store, skip_Proj(get_Sync_pred(pred, i)));
+ if (res)
+ break;
+ }
}
return res;
}
/**
- * walker, optimizes Phi after Stores:
+ * optimize a Store
+ */
+static unsigned optimize_store(ir_node *store)
+{
+ ir_node *ptr, *mem;
+
+ if (get_Store_volatility(store) == volatility_is_volatile)
+ return 0;
+
+ 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_n_uses(ptr) <= 1)
+ return 0;
+
+ mem = get_Store_mem(store);
+
+ /* follow the memory chain as long as there are only Loads */
+ INC_MASTER();
+ return follow_Load_chain_for_Store(store, skip_Proj(mem));
+}
+
+/**
+ * walker, optimizes Phi after Stores to identical places:
* Does the following optimization:
+ * @verbatim
*
* val1 val2 val3 val1 val2 val3
* | | | \ | /
- * Str Str Str \ | /
- * \ | / Phi
+ * Store Store Store \ | /
+ * \ | / PhiData
* \ | / |
- * \ | / Str
- * Phi
+ * \ | / Store
+ * PhiM
*
- * This removes the number of stores and allows for predicated execution.
- * Moves Stores back to the end of a function which may be bad
+ * @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.
*
- * Is only allowed if the predecessor blocks have only one successor.
+ * This is only possible if the predecessor blocks have only one successor.
*/
-static int optimize_phi(ir_node *phi, void *env)
+static unsigned optimize_phi(ir_node *phi, walk_env_t *wenv)
{
- walk_env_t *wenv = env;
int i, n;
- ir_node *store, *ptr, *block, *phiM, *phiD, *exc, *projM;
+ ir_node *store, *old_store, *ptr, *block, *phi_block, *phiM, *phiD, *exc, *projM;
ir_mode *mode;
- ir_node **inM, **inD;
+ ir_node **inM, **inD, **stores;
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;
store = skip_Proj(get_Phi_pred(phi, 0));
+ old_store = store;
if (get_irn_op(store) != op_Store)
return 0;
- /* abort on bad blocks */
- if (is_Bad(get_nodes_block(store)))
+ block = get_nodes_block(store);
+
+ /* abort on dead blocks */
+ if (is_Block_dead(block))
return 0;
- /* check if the block has only one output */
- bl_info = get_irn_link(get_nodes_block(store));
- if (bl_info->flags)
+ /* check if the block is post dominated by Phi-block
+ and has no exception exit */
+ bl_info = get_irn_link(block);
+ if (bl_info->flags & BLOCK_HAS_EXC)
+ return 0;
+
+ phi_block = get_nodes_block(phi);
+ if (! block_postdominates(phi_block, block))
return 0;
/* this is the address of the store */
if (get_irn_op(pred) != op_Store)
return 0;
- if (mode != get_irn_mode(get_Store_value(pred)) || ptr != get_Store_ptr(pred))
+ if (ptr != get_Store_ptr(pred) || mode != get_irn_mode(get_Store_value(pred)))
return 0;
info = get_irn_link(pred);
if (exc != info->exc_block)
return 0;
- /* abort on bad blocks */
- if (is_Bad(get_nodes_block(store)))
+ /* abort on dead blocks */
+ block = get_nodes_block(pred);
+ if (is_Block_dead(block))
return 0;
- /* check if the block has only one output */
- bl_info = get_irn_link(get_nodes_block(store));
- if (bl_info->flags)
+ /* check if the block is post dominated by Phi-block
+ and has no exception exit. Note that block must be different from
+ Phi-block, else we would move a Store from end End of a block to its
+ Start... */
+ bl_info = get_irn_link(block);
+ if (bl_info->flags & BLOCK_HAS_EXC)
+ return 0;
+ if (block == phi_block || ! block_postdominates(phi_block, block))
return 0;
}
/*
* ok, when we are here, we found all predecessors of a Phi that
- * are Stores to the same address. 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:
+ * 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 | \ | /
- * \ | / Phi
+ * \ | / PhiData
* \ | / |
* \ | / Str
- * Phi
+ * PhiM
*
* Is only allowed if the predecessor blocks have only one successor.
*/
- /* first step: collect all inputs */
+ NEW_ARR_A(ir_node *, stores, n);
NEW_ARR_A(ir_node *, inM, n);
NEW_ARR_A(ir_node *, inD, n);
NEW_ARR_A(int, idx, n);
+ /* Prepare: Collect all Store nodes. We must do this
+ first because we otherwise may loose a store when exchanging its
+ memory Proj.
+ */
+ for (i = 0; i < n; ++i)
+ stores[i] = skip_Proj(get_Phi_pred(phi, i));
+
+ /* Prepare: Skip the memory Proj: we need this in the case some stores
+ are cascaded.
+ Beware: One Store might be included more than once in the stores[]
+ list, so we must prevent to do the exchange more than once.
+ */
for (i = 0; i < n; ++i) {
- ir_node *pred = skip_Proj(get_Phi_pred(phi, i));
- info = get_irn_link(pred);
+ ir_node *store = stores[i];
+ ir_node *proj_m;
+
+ info = get_irn_link(store);
+ proj_m = info->projs[pn_Store_M];
+
+ if (is_Proj(proj_m) && get_Proj_pred(proj_m) == store)
+ exchange(proj_m, get_Store_mem(store));
+ }
+
+ /* first step: collect all inputs */
+ for (i = 0; i < n; ++i) {
+ ir_node *store = stores[i];
+ info = get_irn_link(store);
- inM[i] = get_Store_mem(pred);
- inD[i] = get_Store_value(pred);
+ inM[i] = get_Store_mem(store);
+ inD[i] = get_Store_value(store);
idx[i] = info->exc_idx;
}
block = get_nodes_block(phi);
/* 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);
if (n > 1) {
/* the exception block should be optimized as some inputs are identical now */
}
+
+ res |= CF_CHANGED;
}
- /* sixt step: replace old Phi */
+ /* sixth step: replace old Phi */
exchange(phi, projM);
- return 1;
+ return res | DF_CHANGED;
}
/**
- * walker, collects all Load/Store/Proj nodes
+ * walker, do the optimizations
*/
static void do_load_store_optimize(ir_node *n, void *env)
{
break;
case iro_Phi:
- wenv->changes |= optimize_phi(n, env);
+ wenv->changes |= optimize_phi(n, wenv);
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;
+ edges_assure(irg);
+
+ /* for Phi optimization post-dominators are needed ... */
+ assure_postdoms(irg);
+
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);
/* Handle graph state */
if (env.changes) {
- if (get_irg_outs_state(current_ir_graph) == outs_consistent)
- set_irg_outs_inconsistent(current_ir_graph);
+ if (get_irg_outs_state(irg) == outs_consistent)
+ set_irg_outs_inconsistent(irg);
+ }
- /* 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
+ have Bad() predecessors. */
+ set_irg_doms_inconsistent(irg);
}
}
projects / libfirm / blobdiff