CbC/CbC_gcc: gcc/tree-ssa-ter.c comparison

comparison gcc/tree-ssa-ter.c @ 55:77e2b8dfacca gcc-4.4.5

update it from 4.4.3 to 4.5.0

author	ryoma <e075725@ie.u-ryukyu.ac.jp>
date	Fri, 12 Feb 2010 23:39:51 +0900
parents	a06113de4d67
children	b7f97abdc517

comparison

equal deleted inserted replaced

-:c156f1bd5cd9
+:77e2b8dfacca
 /* Temporary Expression Replacement (TER)
 Replace SSA version variables during out-of-ssa with their defining
 expression if there is only one use of the variable.
 This pass is required in order for the RTL expansion pass to see larger
 chunks of code.  This allows it to make better choices on RTL pattern
 selection.  When expand is rewritten and merged with out-of-ssa, and
 understands SSA, this should be eliminated.
 A pass is made through the function, one block at a time.  No cross block
 information is tracked.
 Variables which only have one use, and whose defining stmt is considered
 a replaceable expression (see is_replaceable_p) are tracked to see whether
 they can be replaced at their use location.
 n_12 = C * 10
 a_2 = b_5 + 6
 v_9 = a_2 * n_12
 if there are the only use of n_12 and a_2, TER will substitute in their
 which will then have the ssa_name assigned to regular variables, and the
 resulting code which will be passed to the expander looks something like:
 v = (b + 6) * (C * 10)
 This requires ensuring that none of the variables used by the expression
 change between the def point and where it is used.  Furthermore, if any
 of the ssa_names used in this expression are themselves replaceable, we
 have to ensure none of that expressions' arguments change either.
 Although SSA_NAMES themselves don't change, this pass is performed after
 coalescing has coalesced different SSA_NAMES together, so there could be a
 definition of an SSA_NAME which is coalesced with a use that causes a
 problem, i.e.,
 PHI b_5 = <b_8(2), b_14(1)>
 <...>
 a_2 = b_5 + 6
 b_8 = c_4 + 4
 v_9 = a_2 * n_12
 If b_5, b_8 and b_14 are all coalesced together...
 The expression b_5 + 6 CANNOT replace the use in the statement defining v_9
 because b_8 is in fact killing the value of b_5 since they share a partition
 and will be assigned the same memory or register location.
 TER implements this but stepping through the instructions in a block and
 tracking potential expressions for replacement, and the partitions they are
 dependent on.  Expressions are represented by the SSA_NAME_VERSION of the
 DEF on the LHS of a GIMPLE_ASSIGN and the expression is the RHS.
 When a stmt is determined to be a possible replacement expression, the
 following steps are taken:
 EXPR_DECL_UID bitmap is allocated and set to the base variable UID of the
 def and any uses in the expression.  non-NULL means the expression is being
 tracked.  The UID's themselves are used to prevent TER substitution into
 accumulating sequences, i.e.,
 x = x + y
 x = x + z
 x = x + w
 etc.
 this can result in very large expressions which don't accomplish anything
 see PR tree-optimization/17549.
 PARTITION_DEPENDENCIES is another bitmap array, and it has a bit set for any
 partition which is used in the expression.  This is primarily used to remove
 an expression from the partition kill lists when a decision is made whether
 to replace it or not.  This is indexed by ssa version number as well, and
 indicates a partition number.  virtual operands are not tracked individually,
 but they are summarized by an artificial partition called VIRTUAL_PARTITION.
 This means a MAY or MUST def will kill *ALL* expressions that are dependent
 on a virtual operand.
 Note that the EXPR_DECL_UID and this bitmap represent very similar
 information, but the info in one is not easy to obtain from the other.
 KILL_LIST is yet another bitmap array, this time it is indexed by partition
 number, and represents a list of active expressions which will will no
 longer be valid if a definition into this partition takes place.
 PARTITION_IN_USE is simply a bitmap which is used to track which partitions
 currently have something in their kill list.  This is used at the end of
 a block to clear out the KILL_LIST bitmaps at the end of each block.
 NEW_REPLACEABLE_DEPENDENCIES is used as a temporary place to store
 dependencies which will be reused by the current definition. All the uses
 on an expression are processed before anything else is done. If a use is
 determined to be a replaceable expression AND the current stmt is also going
 to be replaceable, all the dependencies of this replaceable use will be
 picked up by the current stmt's expression. Rather than recreate them, they
 processed.
 a_2 = b_5 + 6
 v_8 = a_2 + c_4
 a_2's expression 'b_5 + 6' is determined to be replaceable at the use
 location. It is dependent on the partition 'b_5' is in. This is cached into
 the NEW_REPLACEABLE_DEPENDENCIES bitmap, and when v_8 is examined for
 replaceability, it is a candidate, and it is dependent on the partition
 b_5 is in *NOT* a_2, as well as c_4's partition.
 if v_8 is also replaceable:
 x_9 = v_8 * 5
 x_9 is dependent on partitions b_5, and c_4
 if a statement is found which has either of those partitions written to
 before x_9 is used, then x_9 itself is NOT replaceable.  */
 /* Temporary Expression Replacement (TER) table information.  */
 typedef struct temp_expr_table_d
 {
 var_map map;
 bitmap *partition_dependencies;	/* Partitions expr is dependent on.  */
-gimple *replaceable_expressions;	/* Replacement expression table.  */
+bitmap replaceable_expressions;	/* Replacement expression table.  */
 bitmap *expr_decl_uids;		/* Base uids of exprs.  */
 bitmap *kill_list;			/* Expr's killed by a partition.  */
 int virtual_partition;		/* Pseudo partition for virtual ops.  */
 bitmap partition_in_use;		/* Partitions with kill entries.  */
 bitmap new_replaceable_dependencies;	/* Holding place for pending dep's.  */
 return t;
 }
 /* Free TER table T.  If there are valid replacements, return the expression
 vector.  */
-static gimple *
+static bitmap
 free_temp_expr_table (temp_expr_table_p t)
 {
-gimple *ret = NULL;
+bitmap ret = NULL;
 #ifdef ENABLE_CHECKING
 unsigned x;
 for (x = 0; x <= num_var_partitions (t->map); x++)
 gcc_assert (!t->kill_list[x]);
-for (x = 0; x < num_ssa_names + 1; x++)
+for (x = 0; x < num_ssa_names; x++)
 {
 gcc_assert (t->expr_decl_uids[x] == NULL);
 gcc_assert (t->partition_dependencies[x] == NULL);
 }
 #endif
 static inline bool
 version_to_be_replaced_p (temp_expr_table_p tab, int version)
 {
 if (!tab->replaceable_expressions)
 return false;
-return tab->replaceable_expressions[version] != NULL;
+return bitmap_bit_p (tab->replaceable_expressions, version);
 }
 /* Add partition P to the list if partitions VERSION is dependent on.  TAB is
 the expression table */
 static inline void
 make_dependent_on_partition (temp_expr_table_p tab, int version, int p)
 {
 }
 bitmap_set_bit (tab->kill_list[p], ver);
 }
 /* Remove VER from the partition kill list for P.  TAB is the expression
 table.  */
 static inline void
 remove_from_partition_kill_list (temp_expr_table_p tab, int p, int version)
 {
 #ifdef ENABLE_CHECKING
 gcc_assert (tab->kill_list[p]);
 #endif
 BITMAP_FREE (tab->kill_list[p]);
 }
 }
 /* Add a dependency between the def of ssa VERSION and VAR.  If VAR is
 replaceable by an expression, add a dependence each of the elements of the
 expression.  These are contained in the new_replaceable list.  TAB is the
 expression table.  */
 static void
 add_dependence (temp_expr_table_p tab, int version, tree var)
 i = SSA_NAME_VERSION (var);
 if (version_to_be_replaced_p (tab, i))
 {
 if (!bitmap_empty_p (tab->new_replaceable_dependencies))
 {
 	  /* Version will now be killed by a write to any partition the
 	     substituted expression would have been killed by.  */
 	  EXECUTE_IF_SET_IN_BITMAP (tab->new_replaceable_dependencies, 0, x, bi)
 	    add_to_partition_kill_list (tab, x, version);
 	  /* Rather than set partition_dependencies and in_use lists bit by
 	     bit, simply OR in the new_replaceable_dependencies bits.  */
 	  if (!tab->partition_dependencies[version])
 	    tab->partition_dependencies[version] = BITMAP_ALLOC (NULL);
 	  bitmap_ior_into (tab->partition_dependencies[version],
 			   tab->new_replaceable_dependencies);
 	  bitmap_ior_into (tab->partition_in_use,
 			   tab->new_replaceable_dependencies);
 	  /* It is only necessary to add these once.  */
 	  bitmap_clear (tab->new_replaceable_dependencies);
 	}
 }
 /* Used in this block, but at the TOP of the block, not the end.  */
 if (gimple_code (use_stmt) == GIMPLE_PHI)
 return false;
 /* There must be no VDEFs.  */
-if (!(ZERO_SSA_OPERANDS (stmt, SSA_OP_VDEF)))
+if (gimple_vdef (stmt))
 return false;
 /* Without alias info we can't move around loads.  */
 if (gimple_references_memory_p (stmt) && !optimize)
 return false;
 /* Float expressions must go through memory if float-store is on.  */
 if (flag_float_store
 && FLOAT_TYPE_P (gimple_expr_type (stmt)))
 return false;
 /* An assignment with a register variable on the RHS is not
 replaceable.  */
 return true;
 }
 /* This function will remove the expression for VERSION from replacement
 consideration in table TAB.  If FREE_EXPR is true, then remove the
 expression from consideration as well by freeing the decl uid bitmap.  */
 static void
 finished_with_expr (temp_expr_table_p tab, int version, bool free_expr)
 {
 }
 /* Create an expression entry for a replaceable expression.  */
 static void
 process_replaceable (temp_expr_table_p tab, gimple stmt)
 {
 tree var, def, basevar;
 int version;
 ssa_op_iter iter;
 	bitmap_set_bit (def_vars, DECL_UID (SSA_NAME_VAR (var)));
 }
 tab->expr_decl_uids[version] = def_vars;
 /* If there are VUSES, add a dependence on virtual defs.  */
-if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_VUSE))
+if (gimple_vuse (stmt))
 {
 make_dependent_on_partition (tab, version, VIRTUAL_PARTITION (tab));
 add_to_partition_kill_list (tab, VIRTUAL_PARTITION (tab), version);
 }
 }
 static inline void
 kill_expr (temp_expr_table_p tab, int partition)
 {
 unsigned version;
 /* Mark every active expr dependent on this var as not replaceable.
 finished_with_expr can modify the bitmap, so we can't execute over it.  */
 while (tab->kill_list[partition])
 {
 version = bitmap_first_set_bit (tab->kill_list[partition]);
 finished_with_expr (tab, version, true);
 gcc_assert (!tab->kill_list[partition]);
 #endif
 }
 /* This function kills all expressions in TAB which are dependent on virtual
 partitions.  */
 static inline void
 kill_virtual_exprs (temp_expr_table_p tab)
 {
 {
 int version = SSA_NAME_VERSION (var);
 /* Move the dependence list to the pending listpending.  */
 if (more_replacing && tab->partition_dependencies[version])
 bitmap_ior_into (tab->new_replaceable_dependencies,
 		     tab->partition_dependencies[version]);
 finished_with_expr (tab, version, !more_replacing);
 /* Set the replaceable expression.  */
 if (!tab->replaceable_expressions)
-tab->replaceable_expressions = XCNEWVEC (gimple, num_ssa_names + 1);
+tab->replaceable_expressions = BITMAP_ALLOC (NULL);
-tab->replaceable_expressions[version] = SSA_NAME_DEF_STMT (var);
+bitmap_set_bit (tab->replaceable_expressions, version);
 }
 /* This function processes basic block BB, and looks for variables which can
 be replaced by their expressions.  Results are stored in the table TAB.  */
 bool stmt_replaceable;
 for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
 {
 stmt = gsi_stmt (bsi);
+if (is_gimple_debug (stmt))
+	continue;
 stmt_replaceable = is_replaceable_p (stmt);
 /* Determine if this stmt finishes an existing expression.  */
 FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE)
 			same_root_var = true;
 			break;
 		      }
 		  }
 	      /* Mark expression as replaceable unless stmt is volatile or the
 		 def variable has the same root variable as something in the
 		 substitution list.  */
 	      if (gimple_has_volatile_ops (stmt) || same_root_var)
 		finished_with_expr (tab, ver, true);
 	      else
 		mark_replaceable (tab, use, stmt_replaceable);
 	    }
 	}
 /* Next, see if this stmt kills off an active expression.  */
 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
 	{
 	  partition = var_to_partition (map, def);
 	  if (partition != NO_PARTITION && tab->kill_list[partition])
 /* Free any unused dependency lists.  */
 bitmap_clear (tab->new_replaceable_dependencies);
 /* A V_{MAY,MUST}_DEF kills any expression using a virtual operand,
 	 including the current stmt.  */
-if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_VIRTUAL_DEFS))
+if (gimple_vdef (stmt))
 kill_virtual_exprs (tab);
 }
 }
 /* This function is the driver routine for replacement of temporary expressions
 in the SSA->normal phase, operating on MAP.  If there are replaceable
 expressions, a table is returned which maps SSA versions to the
 expressions they should be replaced with.  A NULL_TREE indicates no
 replacement should take place.  If there are no replacements at all,
 NULL is returned by the function, otherwise an expression vector indexed
 by SSA_NAME version numbers.  */
-extern gimple *
+extern bitmap
 find_replaceable_exprs (var_map map)
 {
 basic_block bb;
 temp_expr_table_p table;
-gimple *ret;
+bitmap ret;
 table = new_temp_expr_table (map);
 FOR_EACH_BB (bb)
 {
 find_replaceable_in_bb (table, bb);
 #endif
 }
 ret = free_temp_expr_table (table);
 return ret;
 }
 /* Dump TER expression table EXPR to file F.  */
 void
-dump_replaceable_exprs (FILE *f, gimple *expr)
+dump_replaceable_exprs (FILE *f, bitmap expr)
 {
 tree var;
 unsigned x;
 fprintf (f, "\nReplacing Expressions\n");
 for (x = 0; x < num_ssa_names; x++)
-if (expr[x])
+if (bitmap_bit_p (expr, x))
 {
 	var = ssa_name (x);
 	print_generic_expr (f, var, TDF_SLIM);
 	fprintf (f, " replace with --> ");
-	print_gimple_stmt (f, expr[x], 0, TDF_SLIM);
+	print_gimple_stmt (f, SSA_NAME_DEF_STMT (var), 0, TDF_SLIM);
 	fprintf (f, "\n");
 }
 fprintf (f, "\n");
 }
 debug_ter (FILE *f, temp_expr_table_p t)
 {
 unsigned x, y;
 bitmap_iterator bi;
 fprintf (f, "\nDumping current state of TER\n virtual partition = %d\n",
 	   VIRTUAL_PARTITION (t));
 if (t->replaceable_expressions)
 dump_replaceable_exprs (f, t->replaceable_expressions);
 fprintf (f, "Currently tracking the following expressions:\n");
 for (x = 1; x < num_ssa_names; x++)
 if (t->expr_decl_uids[x])
 {
 print_generic_expr (stderr, ssa_name (x), TDF_SLIM);
 fprintf (f, " dep-parts : ");
 	if (t->partition_dependencies[x]
 	    && !bitmap_empty_p (t->partition_dependencies[x]))
 	  {
 	    EXECUTE_IF_SET_IN_BITMAP (t->partition_dependencies[x], 0, y, bi)
 	      fprintf (f, "P%d ",y);
 	  }
 	EXECUTE_IF_SET_IN_BITMAP (t->expr_decl_uids[x], 0, y, bi)
 	  fprintf (f, "%d ",y);
 	fprintf (stderr, "\n");
 }
 bitmap_print (f, t->partition_in_use, "Partitions in use ",
 		"\npartition KILL lists:\n");
 for (x = 0; x <= num_var_partitions (t->map); x++)
 if (t->kill_list[x])
 {

Mercurial > hg > CbC > CbC_gcc

comparison gcc/tree-ssa-ter.c @ 55:77e2b8dfacca gcc-4.4.5