re PR debug/54551 (DF resets some DEBUG_INSNs unnecessarily)

gcc/ChangeLog:
PR debug/54551
* Makefile.in (VALTRACK_H): Add hash-table.h.
* valtrack.h: Include hash-table.h.
(struct dead_debug_global_entry): New.
(struct dead_debug_hash_descr): New.
(struct dead_debug_global): New.
(struct dead_debug): Rename to...
(struct dead_debug_local): ... this.  Adjust all uses.
(dead_debug_global_init, dead_debug_global_finish): New.
(dead_debug_init): Rename to...
(dead_debug_local_init): ... this.  Adjust all callers.
(dead_debug_finish): Rename to...
(dead_debug_local_finish): ... this.  Adjust all callers.
* valtrack.c (dead_debug_global_init): New.
(dead_debug_init): Rename to...
(dead_debug_local_init): ... this.  Take global parameter.
Save it and initialize used bitmap from it.
(dead_debug_global_find, dead_debug_global_insert): New.
(dead_debug_global_replace_temp): New.
(dead_debug_promote_uses): New.
(dead_debug_finish): Rename to...
(dead_debug_local_finish): ... this.  Promote remaining uses.
(dead_debug_global_finish): New.
(dead_debug_add): Try to replace global temps first.
(dead_debug_insert_temp): Support global replacements.
* dce.c (word_dce_process_block, dce_process_block): Add
global_debug parameter.  Pass it on.
(fast_dce): Initialize, pass on and finalize global_debug.
* df-problems.c (df_set_unused_notes_for_mw): Adjusted.
(df_create_unused_notes, df_note_bb_compute): Likewise.
(df_note_compute): Justify local-only dead debug analysis.
gcc/testsuite/ChangeLog:
PR debug/54551
* gcc.dg/guality/pr54551.c: New.

From-SVN: r192001

1 files changed, 79 insertions, 5 deletions

diff --git a/gcc/valtrack.h b/gcc/valtrack.h
index 9f96f210b1a..303ffa43a8f 100644
--- a/gcc/valtrack.h
+++ b/gcc/valtrack.h
@@ -26,10 +26,71 @@ along with GCC; see the file COPYING3.  If not see
 #include "df.h"
 #include "rtl.h"
 #include "basic-block.h"
+#include "hash-table.h"
 
 /* Debug uses of dead regs.  */
 
+/* Entry that maps a dead pseudo (REG) used in a debug insns that dies
+   at different blocks to the debug temp (DTEMP) it was replaced
+   with.  */
+
+struct dead_debug_global_entry
+{
+  rtx reg;
+  rtx dtemp;
+};
+
+/* Descriptor for hash_table to hash by dead_debug_global_entry's REG
+   and map to DTEMP.  */
+
+struct dead_debug_hash_descr
+{
+  /* The hash table contains pointers to entries of this type.  */
+  typedef struct dead_debug_global_entry T;
+  /* Hash on the pseudo number.  */
+  static inline hashval_t hash (T const *my);
+  /* Entries are identical if they refer to the same pseudo.  */
+  static inline bool equal (T const *my, T const *other);
+  /* Release entries when they're removed.  */
+  static inline void remove (T *p);
+};
+
+/* Hash on the pseudo number.  */
+inline hashval_t
+dead_debug_hash_descr::hash (T const *my)
+{
+  return REGNO (my->reg);
+}
+
+/* Entries are identical if they refer to the same pseudo.  */
+inline bool
+dead_debug_hash_descr::equal (T const *my, T const *other)
+{
+  return my->reg == other->reg;
+}
+
+/* Release entries when they're removed.  */
+inline void
+dead_debug_hash_descr::remove (T *p)
+{
+  XDELETE (p);
+}
+
+/* Maintain a global table of pseudos used in debug insns after their
+   deaths in other blocks, and debug temps their deathpoint values are
+   to be bound to.  */
+
+struct dead_debug_global
+{
+  /* This hash table that maps pseudos to debug temps.  */
+  hash_table <dead_debug_hash_descr> htab;
+  /* For each entry in htab, the bit corresponding to its REGNO will
+     be set.  */
+  bitmap used;
+};
+
 /* Node of a linked list of uses of dead REGs in debug insns.  */
+
 struct dead_debug_use
 {
   df_ref use;
@@ -38,15 +99,25 @@ struct dead_debug_use
 
 /* Linked list of the above, with a bitmap of the REGs in the
    list.  */
-struct dead_debug
+
+struct dead_debug_local
 {
+  /* The first dead_debug_use entry in the list.  */
   struct dead_debug_use *head;
+  /* A pointer to the global tracking data structure.  */
+  struct dead_debug_global *global;
+  /* A bitmap that has bits set for each REG used in the
+     dead_debug_use list, and for each entry in the global hash
+     table.  */
   bitmap used;
+  /* A bitmap that has bits set for each INSN that is to be
+     rescanned.  */
   bitmap to_rescan;
 };
 
 /* This type controls the behavior of dead_debug_insert_temp WRT
    UREGNO and INSN.  */
+
 enum debug_temp_where
   {
     /* Bind a newly-created debug temporary to a REG for UREGNO, and
@@ -62,10 +133,13 @@ enum debug_temp_where
     DEBUG_TEMP_AFTER_WITH_REG = 1
   };
 
-extern void dead_debug_init (struct dead_debug *, bitmap);
-extern void dead_debug_finish (struct dead_debug *, bitmap);
-extern void dead_debug_add (struct dead_debug *, df_ref, unsigned int);
-extern int dead_debug_insert_temp (struct dead_debug *,
+extern void dead_debug_global_init (struct dead_debug_global *, bitmap);
+extern void dead_debug_global_finish (struct dead_debug_global *, bitmap);
+extern void dead_debug_local_init (struct dead_debug_local *, bitmap,
+				   struct dead_debug_global *);
+extern void dead_debug_local_finish (struct dead_debug_local *, bitmap);
+extern void dead_debug_add (struct dead_debug_local *, df_ref, unsigned int);
+extern int dead_debug_insert_temp (struct dead_debug_local *,
 				   unsigned int uregno, rtx insn,
 				   enum debug_temp_where);