Refactor tree-loop-distribution.c for thread safety

This patch refactors tree-loop-distribution.c for thread safety without
use of C11 __thread feature. All global variables were moved to
`class loop_distribution` which is initialized at ::execute time.

From-SVN: r278421

1 files changed, 393 insertions, 270 deletions

diff --git a/gcc/tree-loop-distribution.c b/gcc/tree-loop-distribution.c
index 28eeeb93174..839abb733ae 100644
--- a/gcc/tree-loop-distribution.c
+++ b/gcc/tree-loop-distribution.c
@@ -154,21 +154,10 @@ ddr_hasher::equal (const data_dependence_relation *ddr1,
   return (DDR_A (ddr1) == DDR_A (ddr2) && DDR_B (ddr1) == DDR_B (ddr2));
 }
 
-/* The loop (nest) to be distributed.  */
-static vec<loop_p> loop_nest;
 
-/* Vector of data references in the loop to be distributed.  */
-static vec<data_reference_p> datarefs_vec;
 
-/* If there is nonaddressable data reference in above vector.  */
-static bool has_nonaddressable_dataref_p;
-
-/* Store index of data reference in aux field.  */
 #define DR_INDEX(dr)      ((uintptr_t) (dr)->aux)
 
-/* Hash table for data dependence relation in the loop to be distributed.  */
-static hash_table<ddr_hasher> *ddrs_table;
-
 /* A Reduced Dependence Graph (RDG) vertex representing a statement.  */
 struct rdg_vertex
 {
@@ -215,6 +204,83 @@ struct rdg_edge
 
 #define RDGE_TYPE(E)        ((struct rdg_edge *) ((E)->data))->type
 
+/* Kind of distributed loop.  */
+enum partition_kind {
+    PKIND_NORMAL,
+    /* Partial memset stands for a paritition can be distributed into a loop
+       of memset calls, rather than a single memset call.  It's handled just
+       like a normal parition, i.e, distributed as separate loop, no memset
+       call is generated.
+
+       Note: This is a hacking fix trying to distribute ZERO-ing stmt in a
+       loop nest as deep as possible.  As a result, parloop achieves better
+       parallelization by parallelizing deeper loop nest.  This hack should
+       be unnecessary and removed once distributed memset can be understood
+       and analyzed in data reference analysis.  See PR82604 for more.  */
+    PKIND_PARTIAL_MEMSET,
+    PKIND_MEMSET, PKIND_MEMCPY, PKIND_MEMMOVE
+};
+
+/* Type of distributed loop.  */
+enum partition_type {
+    /* The distributed loop can be executed parallelly.  */
+    PTYPE_PARALLEL = 0,
+    /* The distributed loop has to be executed sequentially.  */
+    PTYPE_SEQUENTIAL
+};
+
+/* Builtin info for loop distribution.  */
+struct builtin_info
+{
+  /* data-references a kind != PKIND_NORMAL partition is about.  */
+  data_reference_p dst_dr;
+  data_reference_p src_dr;
+  /* Base address and size of memory objects operated by the builtin.  Note
+     both dest and source memory objects must have the same size.  */
+  tree dst_base;
+  tree src_base;
+  tree size;
+  /* Base and offset part of dst_base after stripping constant offset.  This
+     is only used in memset builtin distribution for now.  */
+  tree dst_base_base;
+  unsigned HOST_WIDE_INT dst_base_offset;
+};
+
+/* Partition for loop distribution.  */
+struct partition
+{
+  /* Statements of the partition.  */
+  bitmap stmts;
+  /* True if the partition defines variable which is used outside of loop.  */
+  bool reduction_p;
+  location_t loc;
+  enum partition_kind kind;
+  enum partition_type type;
+  /* Data references in the partition.  */
+  bitmap datarefs;
+  /* Information of builtin parition.  */
+  struct builtin_info *builtin;
+};
+
+/* Partitions are fused because of different reasons.  */
+enum fuse_type
+{
+  FUSE_NON_BUILTIN = 0,
+  FUSE_REDUCTION = 1,
+  FUSE_SHARE_REF = 2,
+  FUSE_SAME_SCC = 3,
+  FUSE_FINALIZE = 4
+};
+
+/* Description on different fusing reason.  */
+static const char *fuse_message[] = {
+  "they are non-builtins",
+  "they have reductions",
+  "they have shared memory refs",
+  "they are in the same dependence scc",
+  "there is no point to distribute loop"};
+
+
 /* Dump vertex I in RDG to FILE.  */
 
 static void
@@ -435,11 +501,205 @@ create_rdg_cd_edges (struct graph *rdg, control_dependences *cd, loop_p loop)
     }
 }
 
-/* Build the vertices of the reduced dependence graph RDG.  Return false
-   if that failed.  */
 
-static bool
-create_rdg_vertices (struct graph *rdg, vec<gimple *> stmts, loop_p loop)
+class loop_distribution
+{
+  private:
+  /* The loop (nest) to be distributed.  */
+  vec<loop_p> loop_nest;
+
+  /* Vector of data references in the loop to be distributed.  */
+  vec<data_reference_p> datarefs_vec;
+
+  /* If there is nonaddressable data reference in above vector.  */
+  bool has_nonaddressable_dataref_p;
+
+  /* Store index of data reference in aux field.  */
+
+  /* Hash table for data dependence relation in the loop to be distributed.  */
+  hash_table<ddr_hasher> *ddrs_table;
+
+  /* Array mapping basic block's index to its topological order.  */
+  int *bb_top_order_index;
+  /* And size of the array.  */
+  int bb_top_order_index_size;
+
+  /* Build the vertices of the reduced dependence graph RDG.  Return false
+     if that failed.  */
+  bool create_rdg_vertices (struct graph *rdg, vec<gimple *> stmts, loop_p loop);
+
+  /* Initialize STMTS with all the statements of LOOP.  We use topological
+     order to discover all statements.  The order is important because
+     generate_loops_for_partition is using the same traversal for identifying
+     statements in loop copies.  */
+  void stmts_from_loop (class loop *loop, vec<gimple *> *stmts);
+
+
+  /* Build the Reduced Dependence Graph (RDG) with one vertex per statement of
+     LOOP, and one edge per flow dependence or control dependence from control
+     dependence CD.  During visiting each statement, data references are also
+     collected and recorded in global data DATAREFS_VEC.  */
+  struct graph * build_rdg (class loop *loop, control_dependences *cd);
+
+/* Merge PARTITION into the partition DEST.  RDG is the reduced dependence
+   graph and we update type for result partition if it is non-NULL.  */
+  void partition_merge_into (struct graph *rdg,
+			     partition *dest, partition *partition,
+			     enum fuse_type ft);
+
+
+  /* Return data dependence relation for data references A and B.  The two
+     data references must be in lexicographic order wrto reduced dependence
+     graph RDG.  We firstly try to find ddr from global ddr hash table.  If
+     it doesn't exist, compute the ddr and cache it.  */
+  data_dependence_relation * get_data_dependence (struct graph *rdg,
+						  data_reference_p a,
+						  data_reference_p b);
+
+
+  /* In reduced dependence graph RDG for loop distribution, return true if
+     dependence between references DR1 and DR2 leads to a dependence cycle
+     and such dependence cycle can't be resolved by runtime alias check.  */
+  bool data_dep_in_cycle_p (struct graph *rdg, data_reference_p dr1,
+			    data_reference_p dr2);
+
+
+  /* Given reduced dependence graph RDG, PARTITION1 and PARTITION2, update
+     PARTITION1's type after merging PARTITION2 into PARTITION1.  */
+  void update_type_for_merge (struct graph *rdg,
+			      partition *partition1, partition *partition2);
+
+
+  /* Returns a partition with all the statements needed for computing
+     the vertex V of the RDG, also including the loop exit conditions.  */
+  partition *build_rdg_partition_for_vertex (struct graph *rdg, int v);
+
+  /* Given data references DST_DR and SRC_DR in loop nest LOOP and RDG, classify
+     if it forms builtin memcpy or memmove call.  */
+  void classify_builtin_ldst (loop_p loop, struct graph *rdg, partition *partition,
+			      data_reference_p dst_dr, data_reference_p src_dr);
+
+  /* Classifies the builtin kind we can generate for PARTITION of RDG and LOOP.
+     For the moment we detect memset, memcpy and memmove patterns.  Bitmap
+     STMT_IN_ALL_PARTITIONS contains statements belonging to all partitions.
+     Returns true if there is a reduction in all partitions and we
+     possibly did not mark PARTITION as having one for this reason.  */
+
+  bool
+  classify_partition (loop_p loop,
+		      struct graph *rdg, partition *partition,
+		      bitmap stmt_in_all_partitions);
+
+
+  /* Returns true when PARTITION1 and PARTITION2 access the same memory
+     object in RDG.  */
+  bool share_memory_accesses (struct graph *rdg,
+			      partition *partition1, partition *partition2);
+
+  /* For each seed statement in STARTING_STMTS, this function builds
+     partition for it by adding depended statements according to RDG.
+     All partitions are recorded in PARTITIONS.  */
+  void rdg_build_partitions (struct graph *rdg,
+			     vec<gimple *> starting_stmts,
+			     vec<partition *> *partitions);
+
+  /* Compute partition dependence created by the data references in DRS1
+     and DRS2, modify and return DIR according to that.  IF ALIAS_DDR is
+     not NULL, we record dependence introduced by possible alias between
+     two data references in ALIAS_DDRS; otherwise, we simply ignore such
+     dependence as if it doesn't exist at all.  */
+  int pg_add_dependence_edges (struct graph *rdg, int dir, bitmap drs1,
+			       bitmap drs2, vec<ddr_p> *alias_ddrs);
+
+
+  /* Build and return partition dependence graph for PARTITIONS.  RDG is
+     reduced dependence graph for the loop to be distributed.  If IGNORE_ALIAS_P
+     is true, data dependence caused by possible alias between references
+     is ignored, as if it doesn't exist at all; otherwise all depdendences
+     are considered.  */
+  struct graph *build_partition_graph (struct graph *rdg,
+				       vec<struct partition *> *partitions,
+				       bool ignore_alias_p);
+
+  /* Given reduced dependence graph RDG merge strong connected components
+     of PARTITIONS.  If IGNORE_ALIAS_P is true, data dependence caused by
+     possible alias between references is ignored, as if it doesn't exist
+     at all; otherwise all depdendences are considered.  */
+  void merge_dep_scc_partitions (struct graph *rdg, vec<struct partition *>
+				 *partitions, bool ignore_alias_p);
+
+/* This is the main function breaking strong conected components in
+   PARTITIONS giving reduced depdendence graph RDG.  Store data dependence
+   relations for runtime alias check in ALIAS_DDRS.  */
+  void break_alias_scc_partitions (struct graph *rdg, vec<struct partition *>
+				   *partitions, vec<ddr_p> *alias_ddrs);
+
+
+  /* Fuse PARTITIONS of LOOP if necessary before finalizing distribution.
+     ALIAS_DDRS contains ddrs which need runtime alias check.  */
+  void finalize_partitions (class loop *loop, vec<struct partition *>
+			    *partitions, vec<ddr_p> *alias_ddrs);
+
+  /* Distributes the code from LOOP in such a way that producer statements
+     are placed before consumer statements.  Tries to separate only the
+     statements from STMTS into separate loops.  Returns the number of
+     distributed loops.  Set NB_CALLS to number of generated builtin calls.
+     Set *DESTROY_P to whether LOOP needs to be destroyed.  */
+  int distribute_loop (class loop *loop, vec<gimple *> stmts,
+		       control_dependences *cd, int *nb_calls, bool *destroy_p,
+		       bool only_patterns_p);
+
+  /* Compute topological order for basic blocks.  Topological order is
+     needed because data dependence is computed for data references in
+     lexicographical order.  */
+  void bb_top_order_init (void);
+
+  void bb_top_order_destroy (void);
+
+  public:
+
+  /* Getter for bb_top_order.  */
+
+  inline int get_bb_top_order_index_size (void)
+    {
+      return bb_top_order_index_size;
+    }
+
+  inline int get_bb_top_order_index (int i)
+    {
+      return bb_top_order_index[i];
+    }
+
+  unsigned int execute (function *fun);
+};
+
+
+/* If X has a smaller topological sort number than Y, returns -1;
+   if greater, returns 1.  */
+static int
+bb_top_order_cmp_r (const void *x, const void *y, void *loop)
+{
+  loop_distribution *_loop =
+    (loop_distribution *) loop;
+
+  basic_block bb1 = *(const basic_block *) x;
+  basic_block bb2 = *(const basic_block *) y;
+
+  int bb_top_order_index_size = _loop->get_bb_top_order_index_size ();
+
+  gcc_assert (bb1->index < bb_top_order_index_size
+	      && bb2->index < bb_top_order_index_size);
+  gcc_assert (bb1 == bb2
+	      || _loop->get_bb_top_order_index(bb1->index)
+		 != _loop->get_bb_top_order_index(bb2->index));
+
+  return (_loop->get_bb_top_order_index(bb1->index) - 
+	  _loop->get_bb_top_order_index(bb2->index));
+}
+
+bool
+loop_distribution::create_rdg_vertices (struct graph *rdg, vec<gimple *> stmts,
+					loop_p loop)
 {
   int i;
   gimple *stmt;
@@ -476,39 +736,11 @@ create_rdg_vertices (struct graph *rdg, vec<gimple *> stmts, loop_p loop)
   return true;
 }
 
-/* Array mapping basic block's index to its topological order.  */
-static int *bb_top_order_index;
-/* And size of the array.  */
-static int bb_top_order_index_size;
-
-/* If X has a smaller topological sort number than Y, returns -1;
-   if greater, returns 1.  */
-
-static int
-bb_top_order_cmp (const void *x, const void *y)
-{
-  basic_block bb1 = *(const basic_block *) x;
-  basic_block bb2 = *(const basic_block *) y;
-
-  gcc_assert (bb1->index < bb_top_order_index_size
-	      && bb2->index < bb_top_order_index_size);
-  gcc_assert (bb1 == bb2
-	      || bb_top_order_index[bb1->index]
-		 != bb_top_order_index[bb2->index]);
-
-  return (bb_top_order_index[bb1->index] - bb_top_order_index[bb2->index]);
-}
-
-/* Initialize STMTS with all the statements of LOOP.  We use topological
-   order to discover all statements.  The order is important because
-   generate_loops_for_partition is using the same traversal for identifying
-   statements in loop copies.  */
-
-static void
-stmts_from_loop (class loop *loop, vec<gimple *> *stmts)
+void
+loop_distribution::stmts_from_loop (class loop *loop, vec<gimple *> *stmts)
 {
   unsigned int i;
-  basic_block *bbs = get_loop_body_in_custom_order (loop, bb_top_order_cmp);
+  basic_block *bbs = get_loop_body_in_custom_order (loop, this, bb_top_order_cmp_r);
 
   for (i = 0; i < loop->num_nodes; i++)
     {
@@ -557,13 +789,8 @@ free_rdg (struct graph *rdg)
   free_graph (rdg);
 }
 
-/* Build the Reduced Dependence Graph (RDG) with one vertex per statement of
-   LOOP, and one edge per flow dependence or control dependence from control
-   dependence CD.  During visiting each statement, data references are also
-   collected and recorded in global data DATAREFS_VEC.  */
-
-static struct graph *
-build_rdg (class loop *loop, control_dependences *cd)
+struct graph *
+loop_distribution::build_rdg (class loop *loop, control_dependences *cd)
 {
   struct graph *rdg;
 
@@ -586,65 +813,6 @@ build_rdg (class loop *loop, control_dependences *cd)
 }
 
 
-/* Kind of distributed loop.  */
-enum partition_kind {
-    PKIND_NORMAL,
-    /* Partial memset stands for a paritition can be distributed into a loop
-       of memset calls, rather than a single memset call.  It's handled just
-       like a normal parition, i.e, distributed as separate loop, no memset
-       call is generated.
-
-       Note: This is a hacking fix trying to distribute ZERO-ing stmt in a
-       loop nest as deep as possible.  As a result, parloop achieves better
-       parallelization by parallelizing deeper loop nest.  This hack should
-       be unnecessary and removed once distributed memset can be understood
-       and analyzed in data reference analysis.  See PR82604 for more.  */
-    PKIND_PARTIAL_MEMSET,
-    PKIND_MEMSET, PKIND_MEMCPY, PKIND_MEMMOVE
-};
-
-/* Type of distributed loop.  */
-enum partition_type {
-    /* The distributed loop can be executed parallelly.  */
-    PTYPE_PARALLEL = 0,
-    /* The distributed loop has to be executed sequentially.  */
-    PTYPE_SEQUENTIAL
-};
-
-/* Builtin info for loop distribution.  */
-struct builtin_info
-{
-  /* data-references a kind != PKIND_NORMAL partition is about.  */
-  data_reference_p dst_dr;
-  data_reference_p src_dr;
-  /* Base address and size of memory objects operated by the builtin.  Note
-     both dest and source memory objects must have the same size.  */
-  tree dst_base;
-  tree src_base;
-  tree size;
-  /* Base and offset part of dst_base after stripping constant offset.  This
-     is only used in memset builtin distribution for now.  */
-  tree dst_base_base;
-  unsigned HOST_WIDE_INT dst_base_offset;
-};
-
-/* Partition for loop distribution.  */
-struct partition
-{
-  /* Statements of the partition.  */
-  bitmap stmts;
-  /* True if the partition defines variable which is used outside of loop.  */
-  bool reduction_p;
-  location_t loc;
-  enum partition_kind kind;
-  enum partition_type type;
-  /* Data references in the partition.  */
-  bitmap datarefs;
-  /* Information of builtin parition.  */
-  struct builtin_info *builtin;
-};
-
-
 /* Allocate and initialize a partition from BITMAP.  */
 
 static partition *
@@ -689,33 +857,9 @@ partition_reduction_p (partition *partition)
   return partition->reduction_p;
 }
 
-/* Partitions are fused because of different reasons.  */
-enum fuse_type
-{
-  FUSE_NON_BUILTIN = 0,
-  FUSE_REDUCTION = 1,
-  FUSE_SHARE_REF = 2,
-  FUSE_SAME_SCC = 3,
-  FUSE_FINALIZE = 4
-};
-
-/* Description on different fusing reason.  */
-static const char *fuse_message[] = {
-  "they are non-builtins",
-  "they have reductions",
-  "they have shared memory refs",
-  "they are in the same dependence scc",
-  "there is no point to distribute loop"};
-
-static void
-update_type_for_merge (struct graph *, partition *, partition *);
-
-/* Merge PARTITION into the partition DEST.  RDG is the reduced dependence
-   graph and we update type for result partition if it is non-NULL.  */
-
-static void
-partition_merge_into (struct graph *rdg, partition *dest,
-		      partition *partition, enum fuse_type ft)
+void
+loop_distribution::partition_merge_into (struct graph *rdg,
+		      partition *dest, partition *partition, enum fuse_type ft)
 {
   if (dump_file && (dump_flags & TDF_DETAILS))
     {
@@ -1201,13 +1345,9 @@ generate_code_for_partition (class loop *loop,
   return false;
 }
 
-/* Return data dependence relation for data references A and B.  The two
-   data references must be in lexicographic order wrto reduced dependence
-   graph RDG.  We firstly try to find ddr from global ddr hash table.  If
-   it doesn't exist, compute the ddr and cache it.  */
-
-static data_dependence_relation *
-get_data_dependence (struct graph *rdg, data_reference_p a, data_reference_p b)
+data_dependence_relation *
+loop_distribution::get_data_dependence (struct graph *rdg, data_reference_p a,
+					data_reference_p b)
 {
   struct data_dependence_relation ent, **slot;
   struct data_dependence_relation *ddr;
@@ -1228,13 +1368,10 @@ get_data_dependence (struct graph *rdg, data_reference_p a, data_reference_p b)
   return *slot;
 }
 
-/* In reduced dependence graph RDG for loop distribution, return true if
-   dependence between references DR1 and DR2 leads to a dependence cycle
-   and such dependence cycle can't be resolved by runtime alias check.  */
-
-static bool
-data_dep_in_cycle_p (struct graph *rdg,
-		     data_reference_p dr1, data_reference_p dr2)
+bool
+loop_distribution::data_dep_in_cycle_p (struct graph *rdg,
+					data_reference_p dr1,
+					data_reference_p dr2)
 {
   struct data_dependence_relation *ddr;
 
@@ -1264,12 +1401,10 @@ data_dep_in_cycle_p (struct graph *rdg,
   return true;
 }
 
-/* Given reduced dependence graph RDG, PARTITION1 and PARTITION2, update
-   PARTITION1's type after merging PARTITION2 into PARTITION1.  */
-
-static void
-update_type_for_merge (struct graph *rdg,
-		       partition *partition1, partition *partition2)
+void
+loop_distribution::update_type_for_merge (struct graph *rdg,
+					   partition *partition1,
+					   partition *partition2)
 {
   unsigned i, j;
   bitmap_iterator bi, bj;
@@ -1297,11 +1432,8 @@ update_type_for_merge (struct graph *rdg,
     }
 }
 
-/* Returns a partition with all the statements needed for computing
-   the vertex V of the RDG, also including the loop exit conditions.  */
-
-static partition *
-build_rdg_partition_for_vertex (struct graph *rdg, int v)
+partition *
+loop_distribution::build_rdg_partition_for_vertex (struct graph *rdg, int v)
 {
   partition *partition = partition_alloc ();
   auto_vec<int, 3> nodes;
@@ -1595,9 +1727,11 @@ classify_builtin_st (loop_p loop, partition *partition, data_reference_p dr)
 /* Given data references DST_DR and SRC_DR in loop nest LOOP and RDG, classify
    if it forms builtin memcpy or memmove call.  */
 
-static void
-classify_builtin_ldst (loop_p loop, struct graph *rdg, partition *partition,
-		       data_reference_p dst_dr, data_reference_p src_dr)
+void
+loop_distribution::classify_builtin_ldst (loop_p loop, struct graph *rdg,
+					  partition *partition,
+					  data_reference_p dst_dr,
+					  data_reference_p src_dr)
 {
   tree base, size, src_base, src_size;
   auto_vec<tree> dst_steps, src_steps;
@@ -1655,15 +1789,10 @@ classify_builtin_ldst (loop_p loop, struct graph *rdg, partition *partition,
   return;
 }
 
-/* Classifies the builtin kind we can generate for PARTITION of RDG and LOOP.
-   For the moment we detect memset, memcpy and memmove patterns.  Bitmap
-   STMT_IN_ALL_PARTITIONS contains statements belonging to all partitions.
-   Returns true if there is a reduction in all partitions and we
-   possibly did not mark PARTITION as having one for this reason.  */
-
-static bool
-classify_partition (loop_p loop, struct graph *rdg, partition *partition,
-		    bitmap stmt_in_all_partitions)
+bool
+loop_distribution::classify_partition (loop_p loop,
+				       struct graph *rdg, partition *partition,
+				       bitmap stmt_in_all_partitions)
 {
   bitmap_iterator bi;
   unsigned i;
@@ -1721,11 +1850,8 @@ classify_partition (loop_p loop, struct graph *rdg, partition *partition,
   return has_reduction;
 }
 
-/* Returns true when PARTITION1 and PARTITION2 access the same memory
-   object in RDG.  */
-
-static bool
-share_memory_accesses (struct graph *rdg,
+bool
+loop_distribution::share_memory_accesses (struct graph *rdg,
 		       partition *partition1, partition *partition2)
 {
   unsigned i, j;
@@ -1772,10 +1898,10 @@ share_memory_accesses (struct graph *rdg,
    partition for it by adding depended statements according to RDG.
    All partitions are recorded in PARTITIONS.  */
 
-static void
-rdg_build_partitions (struct graph *rdg,
-		      vec<gimple *> starting_stmts,
-		      vec<partition *> *partitions)
+void
+loop_distribution::rdg_build_partitions (struct graph *rdg,
+					 vec<gimple *> starting_stmts,
+					 vec<partition *> *partitions)
 {
   auto_bitmap processed;
   int i;
@@ -1891,14 +2017,8 @@ partition_contains_all_rw (struct graph *rdg,
   return false;
 }
 
-/* Compute partition dependence created by the data references in DRS1
-   and DRS2, modify and return DIR according to that.  IF ALIAS_DDR is
-   not NULL, we record dependence introduced by possible alias between
-   two data references in ALIAS_DDRS; otherwise, we simply ignore such
-   dependence as if it doesn't exist at all.  */
-
-static int
-pg_add_dependence_edges (struct graph *rdg, int dir,
+int
+loop_distribution::pg_add_dependence_edges (struct graph *rdg, int dir,
 			 bitmap drs1, bitmap drs2, vec<ddr_p> *alias_ddrs)
 {
   unsigned i, j;
@@ -2114,10 +2234,10 @@ free_partition_graph_vdata (struct graph *pg)
    is ignored, as if it doesn't exist at all; otherwise all depdendences
    are considered.  */
 
-static struct graph *
-build_partition_graph (struct graph *rdg,
-		       vec<struct partition *> *partitions,
-		       bool ignore_alias_p)
+struct graph *
+loop_distribution::build_partition_graph (struct graph *rdg,
+					  vec<struct partition *> *partitions,
+					  bool ignore_alias_p)
 {
   int i, j;
   struct partition *partition1, *partition2;
@@ -2199,15 +2319,10 @@ sort_partitions_by_post_order (struct graph *pg,
     }
 }
 
-/* Given reduced dependence graph RDG merge strong connected components
-   of PARTITIONS.  If IGNORE_ALIAS_P is true, data dependence caused by
-   possible alias between references is ignored, as if it doesn't exist
-   at all; otherwise all depdendences are considered.  */
-
-static void
-merge_dep_scc_partitions (struct graph *rdg,
-			  vec<struct partition *> *partitions,
-			  bool ignore_alias_p)
+void
+loop_distribution::merge_dep_scc_partitions (struct graph *rdg,
+					     vec<struct partition *> *partitions,
+					     bool ignore_alias_p)
 {
   struct partition *partition1, *partition2;
   struct pg_vdata *data;
@@ -2280,11 +2395,10 @@ pg_collect_alias_ddrs (struct graph *g, struct graph_edge *e, void *data)
 /* This is the main function breaking strong conected components in
    PARTITIONS giving reduced depdendence graph RDG.  Store data dependence
    relations for runtime alias check in ALIAS_DDRS.  */
-
-static void
-break_alias_scc_partitions (struct graph *rdg,
-			    vec<struct partition *> *partitions,
-			    vec<ddr_p> *alias_ddrs)
+void
+loop_distribution::break_alias_scc_partitions (struct graph *rdg,
+					       vec<struct partition *> *partitions,
+					       vec<ddr_p> *alias_ddrs)
 {
   int i, j, k, num_sccs, num_sccs_no_alias;
   /* Build partition dependence graph.  */
@@ -2710,12 +2824,10 @@ fuse_memset_builtins (vec<struct partition *> *partitions)
     }
 }
 
-/* Fuse PARTITIONS of LOOP if necessary before finalizing distribution.
-   ALIAS_DDRS contains ddrs which need runtime alias check.  */
-
-static void
-finalize_partitions (class loop *loop, vec<struct partition *> *partitions,
-		     vec<ddr_p> *alias_ddrs)
+void
+loop_distribution::finalize_partitions (class loop *loop,
+					vec<struct partition *> *partitions,
+					vec<ddr_p> *alias_ddrs)
 {
   unsigned i;
   struct partition *partition, *a;
@@ -2770,8 +2882,8 @@ finalize_partitions (class loop *loop, vec<struct partition *> *partitions,
    distributed loops.  Set NB_CALLS to number of generated builtin calls.
    Set *DESTROY_P to whether LOOP needs to be destroyed.  */
 
-static int
-distribute_loop (class loop *loop, vec<gimple *> stmts,
+int
+loop_distribution::distribute_loop (class loop *loop, vec<gimple *> stmts,
 		 control_dependences *cd, int *nb_calls, bool *destroy_p,
 		 bool only_patterns_p)
 {
@@ -3011,40 +3123,27 @@ distribute_loop (class loop *loop, vec<gimple *> stmts,
   return nbp - *nb_calls;
 }
 
-/* Distribute all loops in the current function.  */
-
-namespace {
 
-const pass_data pass_data_loop_distribution =
+void loop_distribution::bb_top_order_init (void)
 {
-  GIMPLE_PASS, /* type */
-  "ldist", /* name */
-  OPTGROUP_LOOP, /* optinfo_flags */
-  TV_TREE_LOOP_DISTRIBUTION, /* tv_id */
-  ( PROP_cfg | PROP_ssa ), /* properties_required */
-  0, /* properties_provided */
-  0, /* properties_destroyed */
-  0, /* todo_flags_start */
-  0, /* todo_flags_finish */
-};
+  int rpo_num;
+  int *rpo = XNEWVEC (int, last_basic_block_for_fn (cfun));
 
-class pass_loop_distribution : public gimple_opt_pass
-{
-public:
-  pass_loop_distribution (gcc::context *ctxt)
-    : gimple_opt_pass (pass_data_loop_distribution, ctxt)
-  {}
+  bb_top_order_index = XNEWVEC (int, last_basic_block_for_fn (cfun));
+  bb_top_order_index_size = last_basic_block_for_fn (cfun);
+  rpo_num = pre_and_rev_post_order_compute_fn (cfun, NULL, rpo, true);
+  for (int i = 0; i < rpo_num; i++)
+    bb_top_order_index[rpo[i]] = i;
 
-  /* opt_pass methods: */
-  virtual bool gate (function *)
-    {
-      return flag_tree_loop_distribution
-	|| flag_tree_loop_distribute_patterns;
-    }
-
-  virtual unsigned int execute (function *);
+  free (rpo);
+}
 
-}; // class pass_loop_distribution
+void loop_distribution::bb_top_order_destroy ()
+{
+  free (bb_top_order_index);
+  bb_top_order_index = NULL;
+  bb_top_order_index_size = 0;
+}
 
 
 /* Given LOOP, this function records seed statements for distribution in
@@ -3131,8 +3230,9 @@ prepare_perfect_loop_nest (class loop *loop)
   return loop;
 }
 
+
 unsigned int
-pass_loop_distribution::execute (function *fun)
+loop_distribution::execute (function *fun)
 {
   class loop *loop;
   bool changed = false;
@@ -3143,22 +3243,7 @@ pass_loop_distribution::execute (function *fun)
   if (number_of_loops (fun) <= 1)
     return 0;
 
-  /* Compute topological order for basic blocks.  Topological order is
-     needed because data dependence is computed for data references in
-     lexicographical order.  */
-  if (bb_top_order_index == NULL)
-    {
-      int rpo_num;
-      int *rpo = XNEWVEC (int, last_basic_block_for_fn (cfun));
-
-      bb_top_order_index = XNEWVEC (int, last_basic_block_for_fn (cfun));
-      bb_top_order_index_size = last_basic_block_for_fn (cfun);
-      rpo_num = pre_and_rev_post_order_compute_fn (cfun, NULL, rpo, true);
-      for (int i = 0; i < rpo_num; i++)
-	bb_top_order_index[rpo[i]] = i;
-
-      free (rpo);
-    }
+  bb_top_order_init ();
 
   FOR_ALL_BB_FN (bb, fun)
     {
@@ -3233,11 +3318,7 @@ pass_loop_distribution::execute (function *fun)
     delete cd;
 
   if (bb_top_order_index != NULL)
-    {
-      free (bb_top_order_index);
-      bb_top_order_index = NULL;
-      bb_top_order_index_size = 0;
-    }
+    bb_top_order_destroy ();
 
   if (changed)
     {
@@ -3259,6 +3340,48 @@ pass_loop_distribution::execute (function *fun)
   return changed ? TODO_cleanup_cfg : 0;
 }
 
+
+/* Distribute all loops in the current function.  */
+
+namespace {
+
+const pass_data pass_data_loop_distribution =
+{
+  GIMPLE_PASS, /* type */
+  "ldist", /* name */
+  OPTGROUP_LOOP, /* optinfo_flags */
+  TV_TREE_LOOP_DISTRIBUTION, /* tv_id */
+  ( PROP_cfg | PROP_ssa ), /* properties_required */
+  0, /* properties_provided */
+  0, /* properties_destroyed */
+  0, /* todo_flags_start */
+  0, /* todo_flags_finish */
+};
+
+class pass_loop_distribution : public gimple_opt_pass
+{
+public:
+  pass_loop_distribution (gcc::context *ctxt)
+    : gimple_opt_pass (pass_data_loop_distribution, ctxt)
+  {}
+
+  /* opt_pass methods: */
+  virtual bool gate (function *)
+    {
+      return flag_tree_loop_distribution
+	|| flag_tree_loop_distribute_patterns;
+    }
+
+  virtual unsigned int execute (function *);
+
+}; // class pass_loop_distribution
+
+unsigned int
+pass_loop_distribution::execute (function *fun)
+{
+  return loop_distribution ().execute (fun);
+}
+
 } // anon namespace
 
 gimple_opt_pass *