/* Copy propagation and SSA_NAME replacement support routines.
- Copyright (C) 2004, 2005 Free Software Foundation, Inc.
+ Copyright (C) 2004, 2005, 2006, 2007, 2008, 2010
+ Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2, or (at your option)
+the Free Software Foundation; either version 3, or (at your option)
any later version.
GCC is distributed in the hope that it will be useful,
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
-along with GCC; see the file COPYING. If not, write to
-the Free Software Foundation, 51 Franklin Street, Fifth Floor,
-Boston, MA 02110-1301, USA. */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "tm.h"
#include "tree.h"
#include "flags.h"
-#include "rtl.h"
#include "tm_p.h"
-#include "ggc.h"
#include "basic-block.h"
#include "output.h"
-#include "expr.h"
#include "function.h"
-#include "diagnostic.h"
+#include "tree-pretty-print.h"
+#include "gimple-pretty-print.h"
#include "timevar.h"
#include "tree-dump.h"
#include "tree-flow.h"
#include "tree-pass.h"
#include "tree-ssa-propagate.h"
#include "langhooks.h"
+#include "cfgloop.h"
/* This file implements the copy propagation pass and provides a
handful of interfaces for performing const/copy propagation and
tree type_d = TREE_TYPE (dest);
tree type_o = TREE_TYPE (orig);
- /* Do not copy between types for which we *do* need a conversion. */
- if (!tree_ssa_useless_type_conversion_1 (type_d, type_o))
+ /* If ORIG flows in from an abnormal edge, it cannot be propagated. */
+ if (TREE_CODE (orig) == SSA_NAME
+ && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (orig))
return false;
- /* FIXME. GIMPLE is allowing pointer assignments and comparisons of
- pointers that have different alias sets. This means that these
- pointers will have different memory tags associated to them.
-
- If we allow copy propagation in these cases, statements de-referencing
- the new pointer will now have a reference to a different memory tag
- with potentially incorrect SSA information.
-
- This was showing up in libjava/java/util/zip/ZipFile.java with code
- like:
-
- struct java.io.BufferedInputStream *T.660;
- struct java.io.BufferedInputStream *T.647;
- struct java.io.InputStream *is;
- struct java.io.InputStream *is.662;
- [ ... ]
- T.660 = T.647;
- is = T.660; <-- This ought to be type-casted
- is.662 = is;
-
- Also, f/name.c exposed a similar problem with a COND_EXPR predicate
- that was causing DOM to generate and equivalence with two pointers of
- alias-incompatible types:
-
- struct _ffename_space *n;
- struct _ffename *ns;
- [ ... ]
- if (n == ns)
- goto lab;
- ...
- lab:
- return n;
-
- I think that GIMPLE should emit the appropriate type-casts. For the
- time being, blocking copy-propagation in these cases is the safe thing
- to do. */
+ /* If DEST is an SSA_NAME that flows from an abnormal edge, then it
+ cannot be replaced. */
if (TREE_CODE (dest) == SSA_NAME
- && TREE_CODE (orig) == SSA_NAME
- && POINTER_TYPE_P (type_d)
- && POINTER_TYPE_P (type_o))
- {
- tree mt_dest = var_ann (SSA_NAME_VAR (dest))->symbol_mem_tag;
- tree mt_orig = var_ann (SSA_NAME_VAR (orig))->symbol_mem_tag;
- if (mt_dest && mt_orig && mt_dest != mt_orig)
- return false;
- else if (!lang_hooks.types_compatible_p (type_d, type_o))
- return false;
- else if (get_alias_set (TREE_TYPE (type_d)) !=
- get_alias_set (TREE_TYPE (type_o)))
- return false;
- }
+ && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (dest))
+ return false;
- /* If the destination is a SSA_NAME for a virtual operand, then we have
- some special cases to handle. */
+ /* Do not copy between types for which we *do* need a conversion. */
+ if (!useless_type_conversion_p (type_d, type_o))
+ return false;
+
+ /* Propagating virtual operands is always ok. */
if (TREE_CODE (dest) == SSA_NAME && !is_gimple_reg (dest))
{
- /* If both operands are SSA_NAMEs referring to virtual operands, then
- we can always propagate. */
- if (TREE_CODE (orig) == SSA_NAME
- && !is_gimple_reg (orig))
- return true;
-
- /* We have a "copy" from something like a constant into a virtual
- operand. Reject these. */
- return false;
+ /* But only between virtual operands. */
+ gcc_assert (TREE_CODE (orig) == SSA_NAME && !is_gimple_reg (orig));
+
+ return true;
}
- /* If ORIG flows in from an abnormal edge, it cannot be propagated. */
+ /* Anything else is OK. */
+ return true;
+}
+
+/* Like may_propagate_copy, but use as the destination expression
+ the principal expression (typically, the RHS) contained in
+ statement DEST. This is more efficient when working with the
+ gimple tuples representation. */
+
+bool
+may_propagate_copy_into_stmt (gimple dest, tree orig)
+{
+ tree type_d;
+ tree type_o;
+
+ /* If the statement is a switch or a single-rhs assignment,
+ then the expression to be replaced by the propagation may
+ be an SSA_NAME. Fortunately, there is an explicit tree
+ for the expression, so we delegate to may_propagate_copy. */
+
+ if (gimple_assign_single_p (dest))
+ return may_propagate_copy (gimple_assign_rhs1 (dest), orig);
+ else if (gimple_code (dest) == GIMPLE_SWITCH)
+ return may_propagate_copy (gimple_switch_index (dest), orig);
+
+ /* In other cases, the expression is not materialized, so there
+ is no destination to pass to may_propagate_copy. On the other
+ hand, the expression cannot be an SSA_NAME, so the analysis
+ is much simpler. */
+
if (TREE_CODE (orig) == SSA_NAME
&& SSA_NAME_OCCURS_IN_ABNORMAL_PHI (orig))
return false;
- /* If DEST is an SSA_NAME that flows from an abnormal edge, then it
- cannot be replaced. */
- if (TREE_CODE (dest) == SSA_NAME
- && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (dest))
+ if (is_gimple_assign (dest))
+ type_d = TREE_TYPE (gimple_assign_lhs (dest));
+ else if (gimple_code (dest) == GIMPLE_COND)
+ type_d = boolean_type_node;
+ else if (is_gimple_call (dest)
+ && gimple_call_lhs (dest) != NULL_TREE)
+ type_d = TREE_TYPE (gimple_call_lhs (dest));
+ else
+ gcc_unreachable ();
+
+ type_o = TREE_TYPE (orig);
+
+ if (!useless_type_conversion_p (type_d, type_o))
return false;
- /* Anything else is OK. */
return true;
}
}
-/* Given two SSA_NAMEs pointers ORIG and NEW such that we are copy
- propagating NEW into ORIG, consolidate aliasing information so that
- they both share the same memory tags. */
-
-void
-merge_alias_info (tree orig, tree new)
-{
- tree new_sym = SSA_NAME_VAR (new);
- tree orig_sym = SSA_NAME_VAR (orig);
- var_ann_t new_ann = var_ann (new_sym);
- var_ann_t orig_ann = var_ann (orig_sym);
-
- gcc_assert (POINTER_TYPE_P (TREE_TYPE (orig)));
- gcc_assert (POINTER_TYPE_P (TREE_TYPE (new)));
-
-#if defined ENABLE_CHECKING
- gcc_assert (lang_hooks.types_compatible_p (TREE_TYPE (orig),
- TREE_TYPE (new)));
-
- /* If the pointed-to alias sets are different, these two pointers
- would never have the same memory tag. In this case, NEW should
- not have been propagated into ORIG. */
- gcc_assert (get_alias_set (TREE_TYPE (TREE_TYPE (new_sym)))
- == get_alias_set (TREE_TYPE (TREE_TYPE (orig_sym))));
-#endif
-
- /* Synchronize the symbol tags. If both pointers had a tag and they
- are different, then something has gone wrong. Symbol tags can
- always be merged because they are flow insensitive, all the SSA
- names of the same base DECL share the same symbol tag. */
- if (new_ann->symbol_mem_tag == NULL_TREE)
- new_ann->symbol_mem_tag = orig_ann->symbol_mem_tag;
- else if (orig_ann->symbol_mem_tag == NULL_TREE)
- orig_ann->symbol_mem_tag = new_ann->symbol_mem_tag;
- else
- gcc_assert (new_ann->symbol_mem_tag == orig_ann->symbol_mem_tag);
-
- /* Check that flow-sensitive information is compatible. Notice that
- we may not merge flow-sensitive information here. This function
- is called when propagating equivalences dictated by the IL, like
- a copy operation P_i = Q_j, and from equivalences dictated by
- control-flow, like if (P_i == Q_j).
-
- In the former case, P_i and Q_j are equivalent in every block
- dominated by the assignment, so their flow-sensitive information
- is always the same. However, in the latter case, the pointers
- P_i and Q_j are only equivalent in one of the sub-graphs out of
- the predicate, so their flow-sensitive information is not the
- same in every block dominated by the predicate.
-
- Since we cannot distinguish one case from another in this
- function, we can only make sure that if P_i and Q_j have
- flow-sensitive information, they should be compatible. */
- if (SSA_NAME_PTR_INFO (orig) && SSA_NAME_PTR_INFO (new))
- {
- struct ptr_info_def *orig_ptr_info = SSA_NAME_PTR_INFO (orig);
- struct ptr_info_def *new_ptr_info = SSA_NAME_PTR_INFO (new);
-
- /* Note that pointer NEW and ORIG may actually have different
- pointed-to variables (e.g., PR 18291 represented in
- testsuite/gcc.c-torture/compile/pr18291.c). However, since
- NEW is being copy-propagated into ORIG, it must always be
- true that the pointed-to set for pointer NEW is the same, or
- a subset, of the pointed-to set for pointer ORIG. If this
- isn't the case, we shouldn't have been able to do the
- propagation of NEW into ORIG. */
- if (orig_ptr_info->name_mem_tag
- && new_ptr_info->name_mem_tag
- && orig_ptr_info->pt_vars
- && new_ptr_info->pt_vars)
- gcc_assert (bitmap_intersect_p (new_ptr_info->pt_vars,
- orig_ptr_info->pt_vars));
- }
-}
-
-
/* Common code for propagate_value and replace_exp.
Replace use operand OP_P with VAL. FOR_PROPAGATION indicates if the
static void
replace_exp_1 (use_operand_p op_p, tree val,
- bool for_propagation ATTRIBUTE_UNUSED)
+ bool for_propagation ATTRIBUTE_UNUSED)
{
+#if defined ENABLE_CHECKING
tree op = USE_FROM_PTR (op_p);
-#if defined ENABLE_CHECKING
gcc_assert (!(for_propagation
&& TREE_CODE (op) == SSA_NAME
&& TREE_CODE (val) == SSA_NAME
#endif
if (TREE_CODE (val) == SSA_NAME)
- {
- if (TREE_CODE (op) == SSA_NAME && POINTER_TYPE_P (TREE_TYPE (op)))
- merge_alias_info (op, val);
- SET_USE (op_p, val);
- }
+ SET_USE (op_p, val);
else
SET_USE (op_p, unsave_expr_now (val));
}
replace_exp_1 (op_p, val, true);
}
+/* Replace *OP_P with value VAL (assumed to be a constant or another SSA_NAME).
+
+ Use this version when not const/copy propagating values. For example,
+ PRE uses this version when building expressions as they would appear
+ in specific blocks taking into account actions of PHI nodes.
+
+ The statement in which an expression has been replaced should be
+ folded using fold_stmt_inplace. */
+
+void
+replace_exp (use_operand_p op_p, tree val)
+{
+ replace_exp_1 (op_p, val, false);
+}
+
/* Propagate the value VAL (assumed to be a constant or another SSA_NAME)
into the tree pointed to by OP_P.
void
propagate_tree_value (tree *op_p, tree val)
{
-#if defined ENABLE_CHECKING
- gcc_assert (!(TREE_CODE (val) == SSA_NAME
- && TREE_CODE (*op_p) == SSA_NAME
- && !may_propagate_copy (*op_p, val)));
-#endif
+ gcc_checking_assert (!(TREE_CODE (val) == SSA_NAME
+ && *op_p
+ && TREE_CODE (*op_p) == SSA_NAME
+ && !may_propagate_copy (*op_p, val)));
if (TREE_CODE (val) == SSA_NAME)
- {
- if (TREE_CODE (*op_p) == SSA_NAME && POINTER_TYPE_P (TREE_TYPE (*op_p)))
- merge_alias_info (*op_p, val);
- *op_p = val;
- }
+ *op_p = val;
else
*op_p = unsave_expr_now (val);
}
-/* Replace *OP_P with value VAL (assumed to be a constant or another SSA_NAME).
-
- Use this version when not const/copy propagating values. For example,
- PRE uses this version when building expressions as they would appear
- in specific blocks taking into account actions of PHI nodes. */
+/* Like propagate_tree_value, but use as the operand to replace
+ the principal expression (typically, the RHS) contained in the
+ statement referenced by iterator GSI. Note that it is not
+ always possible to update the statement in-place, so a new
+ statement may be created to replace the original. */
void
-replace_exp (use_operand_p op_p, tree val)
+propagate_tree_value_into_stmt (gimple_stmt_iterator *gsi, tree val)
{
- replace_exp_1 (op_p, val, false);
-}
+ gimple stmt = gsi_stmt (*gsi);
+
+ if (is_gimple_assign (stmt))
+ {
+ tree expr = NULL_TREE;
+ if (gimple_assign_single_p (stmt))
+ expr = gimple_assign_rhs1 (stmt);
+ propagate_tree_value (&expr, val);
+ gimple_assign_set_rhs_from_tree (gsi, expr);
+ }
+ else if (gimple_code (stmt) == GIMPLE_COND)
+ {
+ tree lhs = NULL_TREE;
+ tree rhs = build_zero_cst (TREE_TYPE (val));
+ propagate_tree_value (&lhs, val);
+ gimple_cond_set_code (stmt, NE_EXPR);
+ gimple_cond_set_lhs (stmt, lhs);
+ gimple_cond_set_rhs (stmt, rhs);
+ }
+ else if (is_gimple_call (stmt)
+ && gimple_call_lhs (stmt) != NULL_TREE)
+ {
+ gimple new_stmt;
+ tree expr = NULL_TREE;
+ propagate_tree_value (&expr, val);
+ new_stmt = gimple_build_assign (gimple_call_lhs (stmt), expr);
+ move_ssa_defining_stmt_for_defs (new_stmt, stmt);
+ gsi_replace (gsi, new_stmt, false);
+ }
+ else if (gimple_code (stmt) == GIMPLE_SWITCH)
+ propagate_tree_value (gimple_switch_index_ptr (stmt), val);
+ else
+ gcc_unreachable ();
+}
/*---------------------------------------------------------------------------
Copy propagation
---------------------------------------------------------------------------*/
-/* During propagation, we keep chains of variables that are copies of
- one another. If variable X_i is a copy of X_j and X_j is a copy of
- X_k, COPY_OF will contain:
-
- COPY_OF[i].VALUE = X_j
- COPY_OF[j].VALUE = X_k
- COPY_OF[k].VALUE = X_k
+/* Lattice for copy-propagation. The lattice is initialized to
+ UNDEFINED (value == NULL) for SSA names that can become a copy
+ of something or VARYING (value == self) if not (see get_copy_of_val
+ and stmt_may_generate_copy). Other values make the name a COPY
+ of that value.
+
+ When visiting a statement or PHI node the lattice value for an
+ SSA name can transition from UNDEFINED to COPY to VARYING. */
+
+struct prop_value_d {
+ /* Copy-of value. */
+ tree value;
+};
+typedef struct prop_value_d prop_value_t;
- After propagation, the copy-of value for each variable X_i is
- converted into the final value by walking the copy-of chains and
- updating COPY_OF[i].VALUE to be the last element of the chain. */
static prop_value_t *copy_of;
-/* Used in set_copy_of_val to determine if the last link of a copy-of
- chain has changed. */
-static tree *cached_last_copy_of;
-
-/* True if we are doing copy propagation on loads and stores. */
-static bool do_store_copy_prop;
-
/* Return true if this statement may generate a useful copy. */
static bool
-stmt_may_generate_copy (tree stmt)
+stmt_may_generate_copy (gimple stmt)
{
- tree lhs, rhs;
- stmt_ann_t ann;
-
- if (TREE_CODE (stmt) == PHI_NODE)
- return !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (stmt));
+ if (gimple_code (stmt) == GIMPLE_PHI)
+ return !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_phi_result (stmt));
- if (TREE_CODE (stmt) != MODIFY_EXPR)
+ if (gimple_code (stmt) != GIMPLE_ASSIGN)
return false;
- lhs = TREE_OPERAND (stmt, 0);
- rhs = TREE_OPERAND (stmt, 1);
- ann = stmt_ann (stmt);
-
/* If the statement has volatile operands, it won't generate a
useful copy. */
- if (ann->has_volatile_ops)
+ if (gimple_has_volatile_ops (stmt))
return false;
- /* If we are not doing store copy-prop, statements with loads and/or
- stores will never generate a useful copy. */
- if (!do_store_copy_prop
- && !ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))
+ /* Statements with loads and/or stores will never generate a useful copy. */
+ if (gimple_vuse (stmt))
return false;
/* Otherwise, the only statements that generate useful copies are
assignments whose RHS is just an SSA name that doesn't flow
through abnormal edges. */
- return TREE_CODE (rhs) == SSA_NAME && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs);
+ return ((gimple_assign_rhs_code (stmt) == SSA_NAME
+ && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_assign_rhs1 (stmt)))
+ || is_gimple_min_invariant (gimple_assign_rhs1 (stmt)));
}
/* If the variable will never generate a useful copy relation,
make it its own copy. */
val->value = var;
- val->mem_ref = NULL_TREE;
}
return val;
}
+/* Return the variable VAR is a copy of or VAR if VAR isn't the result
+ of a copy. */
-/* Return last link in the copy-of chain for VAR. */
-
-static tree
-get_last_copy_of (tree var)
+static inline tree
+valueize_val (tree var)
{
- tree last;
- int i;
-
- /* Traverse COPY_OF starting at VAR until we get to the last
- link in the chain. Since it is possible to have cycles in PHI
- nodes, the copy-of chain may also contain cycles.
-
- To avoid infinite loops and to avoid traversing lengthy copy-of
- chains, we artificially limit the maximum number of chains we are
- willing to traverse.
-
- The value 5 was taken from a compiler and runtime library
- bootstrap and a mixture of C and C++ code from various sources.
- More than 82% of all copy-of chains were shorter than 5 links. */
-#define LIMIT 5
-
- last = var;
- for (i = 0; i < LIMIT; i++)
+ if (TREE_CODE (var) == SSA_NAME)
{
- tree copy = copy_of[SSA_NAME_VERSION (last)].value;
- if (copy == NULL_TREE || copy == last)
- break;
- last = copy;
+ tree val = get_copy_of_val (var)->value;
+ if (val)
+ return val;
}
-
- /* If we have reached the limit, then we are either in a copy-of
- cycle or the copy-of chain is too long. In this case, just
- return VAR so that it is not considered a copy of anything. */
- return (i < LIMIT ? last : var);
+ return var;
}
-
-/* Set FIRST to be the first variable in the copy-of chain for DEST.
- If DEST's copy-of value or its copy-of chain has changed, return
- true.
-
- MEM_REF is the memory reference where FIRST is stored. This is
- used when DEST is a non-register and we are copy propagating loads
- and stores. */
+/* Set VAL to be the copy of VAR. If that changed return true. */
static inline bool
-set_copy_of_val (tree dest, tree first, tree mem_ref)
+set_copy_of_val (tree var, tree val)
{
- unsigned int dest_ver = SSA_NAME_VERSION (dest);
- tree old_first, old_last, new_last;
-
+ unsigned int ver = SSA_NAME_VERSION (var);
+ tree old;
+
/* Set FIRST to be the first link in COPY_OF[DEST]. If that
changed, return true. */
- old_first = copy_of[dest_ver].value;
- copy_of[dest_ver].value = first;
- copy_of[dest_ver].mem_ref = mem_ref;
+ old = copy_of[ver].value;
+ copy_of[ver].value = val;
- if (old_first != first)
+ if (old != val
+ || (val && !operand_equal_p (old, val, 0)))
return true;
- /* If FIRST and OLD_FIRST are the same, we need to check whether the
- copy-of chain starting at FIRST ends in a different variable. If
- the copy-of chain starting at FIRST ends up in a different
- variable than the last cached value we had for DEST, then return
- true because DEST is now a copy of a different variable.
-
- This test is necessary because even though the first link in the
- copy-of chain may not have changed, if any of the variables in
- the copy-of chain changed its final value, DEST will now be the
- copy of a different variable, so we have to do another round of
- propagation for everything that depends on DEST. */
- old_last = cached_last_copy_of[dest_ver];
- new_last = get_last_copy_of (dest);
- cached_last_copy_of[dest_ver] = new_last;
-
- return (old_last != new_last);
+ return false;
}
dump_copy_of (FILE *file, tree var)
{
tree val;
- sbitmap visited;
print_generic_expr (file, var, dump_flags);
-
if (TREE_CODE (var) != SSA_NAME)
return;
-
- visited = sbitmap_alloc (num_ssa_names);
- sbitmap_zero (visited);
- SET_BIT (visited, SSA_NAME_VERSION (var));
-
- fprintf (file, " copy-of chain: ");
- val = var;
- print_generic_expr (file, val, 0);
+ val = copy_of[SSA_NAME_VERSION (var)].value;
+ fprintf (file, " copy-of chain: ");
+ print_generic_expr (file, var, 0);
fprintf (file, " ");
- while (copy_of[SSA_NAME_VERSION (val)].value)
+ if (!val)
+ fprintf (file, "[UNDEFINED]");
+ else if (val == var)
+ fprintf (file, "[NOT A COPY]");
+ else
{
fprintf (file, "-> ");
- val = copy_of[SSA_NAME_VERSION (val)].value;
print_generic_expr (file, val, 0);
fprintf (file, " ");
- if (TEST_BIT (visited, SSA_NAME_VERSION (val)))
- break;
- SET_BIT (visited, SSA_NAME_VERSION (val));
+ fprintf (file, "[COPY]");
}
-
- val = get_copy_of_val (var)->value;
- if (val == NULL_TREE)
- fprintf (file, "[UNDEFINED]");
- else if (val != var)
- fprintf (file, "[COPY]");
- else
- fprintf (file, "[NOT A COPY]");
-
- sbitmap_free (visited);
}
/* Evaluate the RHS of STMT. If it produces a valid copy, set the LHS
- value and store the LHS into *RESULT_P. If STMT generates more
- than one name (i.e., STMT is an aliased store), it is enough to
- store the first name in the V_MAY_DEF list into *RESULT_P. After
- all, the names generated will be VUSEd in the same statements. */
+ value and store the LHS into *RESULT_P. */
static enum ssa_prop_result
-copy_prop_visit_assignment (tree stmt, tree *result_p)
+copy_prop_visit_assignment (gimple stmt, tree *result_p)
{
tree lhs, rhs;
- prop_value_t *rhs_val;
-
- lhs = TREE_OPERAND (stmt, 0);
- rhs = TREE_OPERAND (stmt, 1);
- gcc_assert (TREE_CODE (rhs) == SSA_NAME);
-
- rhs_val = get_copy_of_val (rhs);
+ lhs = gimple_assign_lhs (stmt);
+ rhs = valueize_val (gimple_assign_rhs1 (stmt));
if (TREE_CODE (lhs) == SSA_NAME)
{
if (!may_propagate_copy (lhs, rhs))
return SSA_PROP_VARYING;
- /* Avoid copy propagation from an inner into an outer loop.
- Otherwise, this may move loop variant variables outside of
- their loops and prevent coalescing opportunities. If the
- value was loop invariant, it will be hoisted by LICM and
- exposed for copy propagation. */
- if (loop_depth_of_name (rhs) > loop_depth_of_name (lhs))
- return SSA_PROP_VARYING;
-
- /* Notice that in the case of assignments, we make the LHS be a
- copy of RHS's value, not of RHS itself. This avoids keeping
- unnecessary copy-of chains (assignments cannot be in a cycle
- like PHI nodes), speeding up the propagation process.
- This is different from what we do in copy_prop_visit_phi_node.
- In those cases, we are interested in the copy-of chains. */
*result_p = lhs;
- if (set_copy_of_val (*result_p, rhs_val->value, rhs_val->mem_ref))
- return SSA_PROP_INTERESTING;
- else
- return SSA_PROP_NOT_INTERESTING;
- }
- else if (stmt_makes_single_store (stmt))
- {
- /* Otherwise, set the names in V_MAY_DEF/V_MUST_DEF operands
- to be a copy of RHS. */
- ssa_op_iter i;
- tree vdef;
- bool changed;
-
- /* This should only be executed when doing store copy-prop. */
- gcc_assert (do_store_copy_prop);
-
- /* Set the value of every VDEF to RHS_VAL. */
- changed = false;
- FOR_EACH_SSA_TREE_OPERAND (vdef, stmt, i, SSA_OP_VIRTUAL_DEFS)
- changed |= set_copy_of_val (vdef, rhs_val->value, lhs);
-
- /* Note that for propagation purposes, we are only interested in
- visiting statements that load the exact same memory reference
- stored here. Those statements will have the exact same list
- of virtual uses, so it is enough to set the output of this
- statement to be its first virtual definition. */
- *result_p = first_vdef (stmt);
-
- if (changed)
+ if (set_copy_of_val (*result_p, rhs))
return SSA_PROP_INTERESTING;
else
return SSA_PROP_NOT_INTERESTING;
}
-
return SSA_PROP_VARYING;
}
-/* Visit the COND_EXPR STMT. Return SSA_PROP_INTERESTING
+/* Visit the GIMPLE_COND STMT. Return SSA_PROP_INTERESTING
if it can determine which edge will be taken. Otherwise, return
SSA_PROP_VARYING. */
static enum ssa_prop_result
-copy_prop_visit_cond_stmt (tree stmt, edge *taken_edge_p)
+copy_prop_visit_cond_stmt (gimple stmt, edge *taken_edge_p)
{
- enum ssa_prop_result retval;
- tree cond;
+ enum ssa_prop_result retval = SSA_PROP_VARYING;
+ location_t loc = gimple_location (stmt);
- cond = COND_EXPR_COND (stmt);
- retval = SSA_PROP_VARYING;
+ tree op0 = gimple_cond_lhs (stmt);
+ tree op1 = gimple_cond_rhs (stmt);
/* The only conditionals that we may be able to compute statically
are predicates involving two SSA_NAMEs. */
- if (COMPARISON_CLASS_P (cond)
- && TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME
- && TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME)
+ if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
{
- tree op0 = get_last_copy_of (TREE_OPERAND (cond, 0));
- tree op1 = get_last_copy_of (TREE_OPERAND (cond, 1));
+ op0 = valueize_val (op0);
+ op1 = valueize_val (op1);
/* See if we can determine the predicate's value. */
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "Trying to determine truth value of ");
fprintf (dump_file, "predicate ");
- print_generic_stmt (dump_file, cond, 0);
+ print_gimple_stmt (dump_file, stmt, 0, 0);
}
/* We can fold COND and get a useful result only when we have
the same SSA_NAME on both sides of a comparison operator. */
if (op0 == op1)
{
- tree folded_cond = fold_binary (TREE_CODE (cond), boolean_type_node,
- op0, op1);
+ tree folded_cond = fold_binary_loc (loc, gimple_cond_code (stmt),
+ boolean_type_node, op0, op1);
if (folded_cond)
{
- basic_block bb = bb_for_stmt (stmt);
+ basic_block bb = gimple_bb (stmt);
*taken_edge_p = find_taken_edge (bb, folded_cond);
if (*taken_edge_p)
retval = SSA_PROP_INTERESTING;
SSA_PROP_VARYING. */
static enum ssa_prop_result
-copy_prop_visit_stmt (tree stmt, edge *taken_edge_p, tree *result_p)
+copy_prop_visit_stmt (gimple stmt, edge *taken_edge_p, tree *result_p)
{
- stmt_ann_t ann;
enum ssa_prop_result retval;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "\nVisiting statement:\n");
- print_generic_stmt (dump_file, stmt, dump_flags);
+ print_gimple_stmt (dump_file, stmt, 0, dump_flags);
fprintf (dump_file, "\n");
}
- ann = stmt_ann (stmt);
-
- if (TREE_CODE (stmt) == MODIFY_EXPR
- && TREE_CODE (TREE_OPERAND (stmt, 1)) == SSA_NAME
- && (do_store_copy_prop
- || TREE_CODE (TREE_OPERAND (stmt, 0)) == SSA_NAME))
+ if (gimple_assign_single_p (stmt)
+ && TREE_CODE (gimple_assign_lhs (stmt)) == SSA_NAME
+ && (TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME
+ || is_gimple_min_invariant (gimple_assign_rhs1 (stmt))))
{
/* If the statement is a copy assignment, evaluate its RHS to
see if the lattice value of its output has changed. */
retval = copy_prop_visit_assignment (stmt, result_p);
}
- else if (TREE_CODE (stmt) == COND_EXPR)
+ else if (gimple_code (stmt) == GIMPLE_COND)
{
/* See if we can determine which edge goes out of a conditional
jump. */
statement again and mark all the definitions in the statement
to be copies of nothing. */
FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_ALL_DEFS)
- set_copy_of_val (def, def, NULL_TREE);
+ set_copy_of_val (def, def);
}
return retval;
set it to be the value of the LHS of PHI. */
static enum ssa_prop_result
-copy_prop_visit_phi_node (tree phi)
+copy_prop_visit_phi_node (gimple phi)
{
enum ssa_prop_result retval;
- int i;
- tree lhs;
- prop_value_t phi_val = { 0, NULL_TREE, NULL_TREE };
+ unsigned i;
+ prop_value_t phi_val = { NULL_TREE };
- lhs = PHI_RESULT (phi);
+ tree lhs = gimple_phi_result (phi);
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "\nVisiting PHI node: ");
- print_generic_expr (dump_file, phi, dump_flags);
- fprintf (dump_file, "\n\n");
+ print_gimple_stmt (dump_file, phi, 0, dump_flags);
}
- for (i = 0; i < PHI_NUM_ARGS (phi); i++)
+ for (i = 0; i < gimple_phi_num_args (phi); i++)
{
prop_value_t *arg_val;
- tree arg = PHI_ARG_DEF (phi, i);
- edge e = PHI_ARG_EDGE (phi, i);
+ tree arg_value;
+ tree arg = gimple_phi_arg_def (phi, i);
+ edge e = gimple_phi_arg_edge (phi, i);
/* We don't care about values flowing through non-executable
edges. */
if (!(e->flags & EDGE_EXECUTABLE))
continue;
- /* Constants in the argument list never generate a useful copy.
- Similarly, names that flow through abnormal edges cannot be
- used to derive copies. */
- if (TREE_CODE (arg) != SSA_NAME || SSA_NAME_OCCURS_IN_ABNORMAL_PHI (arg))
+ /* Names that flow through abnormal edges cannot be used to
+ derive copies. */
+ if (TREE_CODE (arg) == SSA_NAME && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (arg))
{
phi_val.value = lhs;
break;
}
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "\tArgument #%d: ", i);
+ dump_copy_of (dump_file, arg);
+ fprintf (dump_file, "\n");
+ }
+
+ if (TREE_CODE (arg) == SSA_NAME)
+ {
+ arg_val = get_copy_of_val (arg);
+
+ /* If we didn't visit the definition of arg yet treat it as
+ UNDEFINED. This also handles PHI arguments that are the
+ same as lhs. We'll come here again. */
+ if (!arg_val->value)
+ continue;
+
+ arg_value = arg_val->value;
+ }
+ else
+ arg_value = valueize_val (arg);
+
/* Avoid copy propagation from an inner into an outer loop.
Otherwise, this may move loop variant variables outside of
their loops and prevent coalescing opportunities. If the
value was loop invariant, it will be hoisted by LICM and
- exposed for copy propagation. */
- if (loop_depth_of_name (arg) > loop_depth_of_name (lhs))
+ exposed for copy propagation.
+ ??? The value will be always loop invariant.
+ In loop-closed SSA form do not copy-propagate through
+ PHI nodes in blocks with a loop exit edge predecessor. */
+ if (current_loops
+ && TREE_CODE (arg_value) == SSA_NAME
+ && (loop_depth_of_name (arg_value) > loop_depth_of_name (lhs)
+ || (loops_state_satisfies_p (LOOP_CLOSED_SSA)
+ && loop_exit_edge_p (e->src->loop_father, e))))
{
phi_val.value = lhs;
break;
}
- /* If the LHS appears in the argument list, ignore it. It is
- irrelevant as a copy. */
- if (arg == lhs || get_last_copy_of (arg) == lhs)
- continue;
-
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, "\tArgument #%d: ", i);
- dump_copy_of (dump_file, arg);
- fprintf (dump_file, "\n");
- }
-
- arg_val = get_copy_of_val (arg);
-
/* If the LHS didn't have a value yet, make it a copy of the
- first argument we find. Notice that while we make the LHS be
- a copy of the argument itself, we take the memory reference
- from the argument's value so that we can compare it to the
- memory reference of all the other arguments. */
+ first argument we find. */
if (phi_val.value == NULL_TREE)
{
- phi_val.value = arg;
- phi_val.mem_ref = arg_val->mem_ref;
+ phi_val.value = arg_value;
continue;
}
/* If PHI_VAL and ARG don't have a common copy-of chain, then
- this PHI node cannot be a copy operation. Also, if we are
- copy propagating stores and these two arguments came from
- different memory references, they cannot be considered
- copies. */
- if (get_last_copy_of (phi_val.value) != get_last_copy_of (arg)
- || (do_store_copy_prop
- && phi_val.mem_ref
- && arg_val->mem_ref
- && simple_cst_equal (phi_val.mem_ref, arg_val->mem_ref) != 1))
+ this PHI node cannot be a copy operation. */
+ if (phi_val.value != arg_value
+ && !operand_equal_p (phi_val.value, arg_value, 0))
{
phi_val.value = lhs;
break;
}
}
- if (phi_val.value && set_copy_of_val (lhs, phi_val.value, phi_val.mem_ref))
+ if (phi_val.value
+ && may_propagate_copy (lhs, phi_val.value)
+ && set_copy_of_val (lhs, phi_val.value))
retval = (phi_val.value != lhs) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
else
retval = SSA_PROP_NOT_INTERESTING;
if (dump_file && (dump_flags & TDF_DETAILS))
{
- fprintf (dump_file, "\nPHI node ");
+ fprintf (dump_file, "PHI node ");
dump_copy_of (dump_file, lhs);
fprintf (dump_file, "\nTelling the propagator to ");
if (retval == SSA_PROP_INTERESTING)
}
-/* Initialize structures used for copy propagation. PHIS_ONLY is true
- if we should only consider PHI nodes as generating copy propagation
- opportunities. */
+/* Initialize structures used for copy propagation. */
static void
-init_copy_prop (bool phis_only)
+init_copy_prop (void)
{
basic_block bb;
- copy_of = XNEWVEC (prop_value_t, num_ssa_names);
- memset (copy_of, 0, num_ssa_names * sizeof (*copy_of));
-
- cached_last_copy_of = XNEWVEC (tree, num_ssa_names);
- memset (cached_last_copy_of, 0, num_ssa_names * sizeof (*cached_last_copy_of));
+ copy_of = XCNEWVEC (prop_value_t, num_ssa_names);
FOR_EACH_BB (bb)
{
- block_stmt_iterator si;
- tree phi;
+ gimple_stmt_iterator si;
+ int depth = bb->loop_depth;
- for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
+ for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
{
- tree stmt = bsi_stmt (si);
+ gimple stmt = gsi_stmt (si);
+ ssa_op_iter iter;
+ tree def;
/* The only statements that we care about are those that may
generate useful copies. We also need to mark conditional
jumps so that their outgoing edges are added to the work
- lists of the propagator. */
+ lists of the propagator.
+
+ Avoid copy propagation from an inner into an outer loop.
+ Otherwise, this may move loop variant variables outside of
+ their loops and prevent coalescing opportunities. If the
+ value was loop invariant, it will be hoisted by LICM and
+ exposed for copy propagation.
+ ??? This doesn't make sense. */
if (stmt_ends_bb_p (stmt))
- DONT_SIMULATE_AGAIN (stmt) = false;
- else if (!phis_only && stmt_may_generate_copy (stmt))
- DONT_SIMULATE_AGAIN (stmt) = false;
+ prop_set_simulate_again (stmt, true);
+ else if (stmt_may_generate_copy (stmt)
+ /* Since we are iterating over the statements in
+ BB, not the phi nodes, STMT will always be an
+ assignment. */
+ && loop_depth_of_name (gimple_assign_rhs1 (stmt)) <= depth)
+ prop_set_simulate_again (stmt, true);
else
- {
- tree def;
- ssa_op_iter iter;
-
- /* No need to simulate this statement anymore. */
- DONT_SIMULATE_AGAIN (stmt) = true;
+ prop_set_simulate_again (stmt, false);
- /* Mark all the outputs of this statement as not being
- the copy of anything. */
- FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
- set_copy_of_val (def, def, NULL_TREE);
- }
+ /* Mark all the outputs of this statement as not being
+ the copy of anything. */
+ FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
+ if (!prop_simulate_again_p (stmt))
+ set_copy_of_val (def, def);
}
- for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
- DONT_SIMULATE_AGAIN (phi) = false;
+ for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si))
+ {
+ gimple phi = gsi_stmt (si);
+ tree def;
+
+ def = gimple_phi_result (phi);
+ if (!is_gimple_reg (def))
+ prop_set_simulate_again (phi, false);
+ else
+ prop_set_simulate_again (phi, true);
+
+ if (!prop_simulate_again_p (phi))
+ set_copy_of_val (def, def);
+ }
}
}
+/* Callback for substitute_and_fold to get at the final copy-of values. */
+
+static tree
+get_value (tree name)
+{
+ tree val = copy_of[SSA_NAME_VERSION (name)].value;
+ if (val && val != name)
+ return val;
+ return NULL_TREE;
+}
/* Deallocate memory used in copy propagation and do final
substitution. */
static void
fini_copy_prop (void)
{
- size_t i;
- prop_value_t *tmp;
-
+ unsigned i;
+
/* Set the final copy-of value for each variable by traversing the
copy-of chains. */
- tmp = XNEWVEC (prop_value_t, num_ssa_names);
- memset (tmp, 0, num_ssa_names * sizeof (*tmp));
for (i = 1; i < num_ssa_names; i++)
{
tree var = ssa_name (i);
- if (var && copy_of[i].value && copy_of[i].value != var)
- tmp[i].value = get_last_copy_of (var);
+ if (!var
+ || !copy_of[i].value
+ || copy_of[i].value == var)
+ continue;
+
+ /* In theory the points-to solution of all members of the
+ copy chain is their intersection. For now we do not bother
+ to compute this but only make sure we do not lose points-to
+ information completely by setting the points-to solution
+ of the representative to the first solution we find if
+ it doesn't have one already. */
+ if (copy_of[i].value != var
+ && TREE_CODE (copy_of[i].value) == SSA_NAME
+ && POINTER_TYPE_P (TREE_TYPE (var))
+ && SSA_NAME_PTR_INFO (var)
+ && !SSA_NAME_PTR_INFO (copy_of[i].value))
+ duplicate_ssa_name_ptr_info (copy_of[i].value, SSA_NAME_PTR_INFO (var));
}
- substitute_and_fold (tmp, false);
+ /* Don't do DCE if we have loops. That's the simplest way to not
+ destroy the scev cache. */
+ substitute_and_fold (get_value, NULL, !current_loops);
- free (cached_last_copy_of);
free (copy_of);
- free (tmp);
}
/* Main entry point to the copy propagator.
PHIS_ONLY is true if we should only consider PHI nodes as generating
- copy propagation opportunities.
+ copy propagation opportunities.
The algorithm propagates the value COPY-OF using ssa_propagate. For
every variable X_i, COPY-OF(X_i) indicates which variable is X_i created
Visit #2: a_2 is copy-of x_298. Value changed.
Visit #3: a_5 is copy-of x_298. Value changed.
Visit #4: x_1 is copy-of x_298. Stable state reached.
-
+
When visiting PHI nodes, we only consider arguments that flow
through edges marked executable by the propagation engine. So,
when visiting statement #2 for the first time, we will only look at
the first argument (a_24) and optimistically assume that its value
- is the copy of a_24 (x_1).
-
- The problem with this approach is that it may fail to discover copy
- relations in PHI cycles. Instead of propagating copy-of
- values, we actually propagate copy-of chains. For instance:
-
- A_3 = B_1;
- C_9 = A_3;
- D_4 = C_9;
- X_i = D_4;
-
- In this code fragment, COPY-OF (X_i) = { D_4, C_9, A_3, B_1 }.
- Obviously, we are only really interested in the last value of the
- chain, however the propagator needs to access the copy-of chain
- when visiting PHI nodes.
-
- To represent the copy-of chain, we use the array COPY_CHAINS, which
- holds the first link in the copy-of chain for every variable.
- If variable X_i is a copy of X_j, which in turn is a copy of X_k,
- the array will contain:
-
- COPY_CHAINS[i] = X_j
- COPY_CHAINS[j] = X_k
- COPY_CHAINS[k] = X_k
-
- Keeping copy-of chains instead of copy-of values directly becomes
- important when visiting PHI nodes. Suppose that we had the
- following PHI cycle, such that x_52 is already considered a copy of
- x_53:
-
- 1 x_54 = PHI <x_53, x_52>
- 2 x_53 = PHI <x_898, x_54>
-
- Visit #1: x_54 is copy-of x_53 (because x_52 is copy-of x_53)
- Visit #2: x_53 is copy-of x_898 (because x_54 is a copy of x_53,
- so it is considered irrelevant
- as a copy).
- Visit #1: x_54 is copy-of nothing (x_53 is a copy-of x_898 and
- x_52 is a copy of x_53, so
- they don't match)
- Visit #2: x_53 is copy-of nothing
-
- This problem is avoided by keeping a chain of copies, instead of
- the final copy-of value. Propagation will now only keep the first
- element of a variable's copy-of chain. When visiting PHI nodes,
- arguments are considered equal if their copy-of chains end in the
- same variable. So, as long as their copy-of chains overlap, we
- know that they will be a copy of the same variable, regardless of
- which variable that may be).
-
- Propagation would then proceed as follows (the notation a -> b
- means that a is a copy-of b):
-
- Visit #1: x_54 = PHI <x_53, x_52>
- x_53 -> x_53
- x_52 -> x_53
- Result: x_54 -> x_53. Value changed. Add SSA edges.
-
- Visit #1: x_53 = PHI <x_898, x_54>
- x_898 -> x_898
- x_54 -> x_53
- Result: x_53 -> x_898. Value changed. Add SSA edges.
-
- Visit #2: x_54 = PHI <x_53, x_52>
- x_53 -> x_898
- x_52 -> x_53 -> x_898
- Result: x_54 -> x_898. Value changed. Add SSA edges.
-
- Visit #2: x_53 = PHI <x_898, x_54>
- x_898 -> x_898
- x_54 -> x_898
- Result: x_53 -> x_898. Value didn't change. Stable state
-
- Once the propagator stabilizes, we end up with the desired result
- x_53 and x_54 are both copies of x_898. */
+ is the copy of a_24 (x_1). */
-static void
-execute_copy_prop (bool store_copy_prop, bool phis_only)
+static unsigned int
+execute_copy_prop (void)
{
- do_store_copy_prop = store_copy_prop;
- init_copy_prop (phis_only);
+ init_copy_prop ();
ssa_propagate (copy_prop_visit_stmt, copy_prop_visit_phi_node);
fini_copy_prop ();
+ return 0;
}
-
static bool
gate_copy_prop (void)
{
return flag_tree_copy_prop != 0;
}
-static void
-do_copy_prop (void)
-{
- execute_copy_prop (false, false);
-}
-
-struct tree_opt_pass pass_copy_prop =
+struct gimple_opt_pass pass_copy_prop =
{
+ {
+ GIMPLE_PASS,
"copyprop", /* name */
gate_copy_prop, /* gate */
- do_copy_prop, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- TV_TREE_COPY_PROP, /* tv_id */
- PROP_ssa | PROP_alias | PROP_cfg, /* properties_required */
- 0, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- TODO_cleanup_cfg
- | TODO_dump_func
- | TODO_ggc_collect
- | TODO_verify_ssa
- | TODO_update_ssa, /* todo_flags_finish */
- 0 /* letter */
-};
-
-
-static void
-do_phi_only_copy_prop (void)
-{
- execute_copy_prop (false, true);
-}
-
-struct tree_opt_pass pass_phi_only_copy_prop =
-{
- "phionlycopyprop", /* name */
- gate_copy_prop, /* gate */
- do_phi_only_copy_prop, /* execute */
+ execute_copy_prop, /* execute */
NULL, /* sub */
NULL, /* next */
0, /* static_pass_number */
TV_TREE_COPY_PROP, /* tv_id */
- PROP_ssa | PROP_alias | PROP_cfg, /* properties_required */
+ PROP_ssa | PROP_cfg, /* properties_required */
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
TODO_cleanup_cfg
- | TODO_dump_func
- | TODO_ggc_collect
- | TODO_verify_ssa
- | TODO_update_ssa, /* todo_flags_finish */
- 0 /* letter */
-};
-
-
-static bool
-gate_store_copy_prop (void)
-{
- /* STORE-COPY-PROP is enabled only with -ftree-store-copy-prop, but
- when -fno-tree-store-copy-prop is specified, we should run
- regular COPY-PROP. That's why the pass is enabled with either
- flag. */
- return flag_tree_store_copy_prop != 0 || flag_tree_copy_prop != 0;
-}
-
-static void
-store_copy_prop (void)
-{
- /* If STORE-COPY-PROP is not enabled, we just run regular COPY-PROP. */
- execute_copy_prop (flag_tree_store_copy_prop != 0, false);
-}
-
-struct tree_opt_pass pass_store_copy_prop =
-{
- "store_copyprop", /* name */
- gate_store_copy_prop, /* gate */
- store_copy_prop, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- TV_TREE_STORE_COPY_PROP, /* tv_id */
- PROP_ssa | PROP_alias | PROP_cfg, /* properties_required */
- 0, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- TODO_dump_func
- | TODO_cleanup_cfg
| TODO_ggc_collect
| TODO_verify_ssa
- | TODO_update_ssa, /* todo_flags_finish */
- 0 /* letter */
+ | TODO_update_ssa /* todo_flags_finish */
+ }
};
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