tree-ssa-dce.c (simple_dce_from_worklist): Move and rename from tree-ssa-pre.c::remov...

	* tree-ssa-dce.c (simple_dce_from_worklist): Move and rename from
	tree-ssa-pre.c::remove_dead_inserted_code.
	* tree-ssa-dce.h: New file.
	* tree-ssa-pre.c (tree-ssa-dce.h): Include new header file.
	(remove_dead_inserted_code): Move and rename to function
	tree-ssa-dce.c::simple_dce_from_worklist.
	(pass_pre::execute): Update use.

From-SVN: r255426

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index cfda6b3c691b8bbfe386af9d85f84f4110507e21..4d58c0f9aec01f9bc4ed15edca1bf6b6ff28bbb9 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2017-12-05  Bin Cheng  <bin.cheng@arm.com>
+
+       * tree-ssa-dce.c (simple_dce_from_worklist): Move and rename from
+       tree-ssa-pre.c::remove_dead_inserted_code.
+       * tree-ssa-dce.h: New file.
+       * tree-ssa-pre.c (tree-ssa-dce.h): Include new header file.
+       (remove_dead_inserted_code): Move and rename to function
+       tree-ssa-dce.c::simple_dce_from_worklist.
+       (pass_pre::execute): Update use.
+
 2017-12-05  Richard Biener  <rguenther@suse.de>
 
        PR tree-optimization/83277

diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c
index a5f0edf7893b10cb198d1af813c6bb559026e609..8595decc7023316603709e52e868f368418f3e3a 100644 (file)
--- a/gcc/tree-ssa-dce.c
+++ b/gcc/tree-ssa-dce.c
@@ -1723,3 +1723,55 @@ make_pass_cd_dce (gcc::context *ctxt)
 {
   return new pass_cd_dce (ctxt);
 }
+
+
+/* A cheap DCE interface.  WORKLIST is a list of possibly dead stmts and
+   is consumed by this function.  The function has linear complexity in
+   the number of dead stmts with a constant factor like the average SSA
+   use operands number.  */
+
+void
+simple_dce_from_worklist (bitmap worklist)
+{
+  while (! bitmap_empty_p (worklist))
+    {
+      /* Pop item.  */
+      unsigned i = bitmap_first_set_bit (worklist);
+      bitmap_clear_bit (worklist, i);
+
+      tree def = ssa_name (i);
+      /* Removed by somebody else or still in use.  */
+      if (! def || ! has_zero_uses (def))
+       continue;
+
+      gimple *t = SSA_NAME_DEF_STMT (def);
+      if (gimple_has_side_effects (t))
+       continue;
+
+      /* Add uses to the worklist.  */
+      ssa_op_iter iter;
+      use_operand_p use_p;
+      FOR_EACH_PHI_OR_STMT_USE (use_p, t, iter, SSA_OP_USE)
+       {
+         tree use = USE_FROM_PTR (use_p);
+         if (TREE_CODE (use) == SSA_NAME
+             && ! SSA_NAME_IS_DEFAULT_DEF (use))
+           bitmap_set_bit (worklist, SSA_NAME_VERSION (use));
+       }
+
+      /* Remove stmt.  */
+      if (dump_file && (dump_flags & TDF_DETAILS))
+       {
+         fprintf (dump_file, "Removing dead stmt:");
+         print_gimple_stmt (dump_file, t, 0);
+       }
+      gimple_stmt_iterator gsi = gsi_for_stmt (t);
+      if (gimple_code (t) == GIMPLE_PHI)
+       remove_phi_node (&gsi, true);
+      else
+       {
+         gsi_remove (&gsi, true);
+         release_defs (t);
+       }
+    }
+}

diff --git a/gcc/tree-ssa-dce.h b/gcc/tree-ssa-dce.h
new file mode 100644 (file)
index 0000000..2adb086
--- /dev/null
+++ b/gcc/tree-ssa-dce.h
@@ -0,0 +1,22 @@
+/* Copyright (C) 2017 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 3, or (at your option) any
+later version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the 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 COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#ifndef TREE_SSA_DCE_H
+#define TREE_SSA_DCE_H
+extern void simple_dce_from_worklist (bitmap);
+#endif

diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index a9dcd5edd50ecfb6d298e5af844aaab55759df35..999b881becd8963a3bdc222d48c1b580b927ea88 100644 (file)
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -49,6 +49,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "dbgcnt.h"
 #include "domwalk.h"
 #include "tree-ssa-propagate.h"
+#include "tree-ssa-dce.h"
 #include "tree-cfgcleanup.h"
 #include "alias.h"
 
@@ -3995,64 +3996,6 @@ compute_avail (void)
   free (worklist);
 }
 
-/* Cheap DCE of a known set of possibly dead stmts.
-
-   Because we don't follow exactly the standard PRE algorithm, and decide not
-   to insert PHI nodes sometimes, and because value numbering of casts isn't
-   perfect, we sometimes end up inserting dead code.   This simple DCE-like
-   pass removes any insertions we made that weren't actually used.  */
-
-static void
-remove_dead_inserted_code (void)
-{
-  /* ???  Re-use inserted_exprs as worklist not only as initial set.
-     This may end up removing non-inserted code as well.  If we
-     keep inserted_exprs unchanged we could restrict new worklist
-     elements to members of inserted_exprs.  */
-  bitmap worklist = inserted_exprs;
-  while (! bitmap_empty_p (worklist))
-    {
-      /* Pop item.  */
-      unsigned i = bitmap_first_set_bit (worklist);
-      bitmap_clear_bit (worklist, i);
-
-      tree def = ssa_name (i);
-      /* Removed by somebody else or still in use.  */
-      if (! def || ! has_zero_uses (def))
-       continue;
-
-      gimple *t = SSA_NAME_DEF_STMT (def);
-      if (gimple_has_side_effects (t))
-       continue;
-
-      /* Add uses to the worklist.  */
-      ssa_op_iter iter;
-      use_operand_p use_p;
-      FOR_EACH_PHI_OR_STMT_USE (use_p, t, iter, SSA_OP_USE)
-       {
-         tree use = USE_FROM_PTR (use_p);
-         if (TREE_CODE (use) == SSA_NAME
-             && ! SSA_NAME_IS_DEFAULT_DEF (use))
-           bitmap_set_bit (worklist, SSA_NAME_VERSION (use));
-       }
-
-      /* Remove stmt.  */
-      if (dump_file && (dump_flags & TDF_DETAILS))
-       {
-         fprintf (dump_file, "Removing unnecessary insertion:");
-         print_gimple_stmt (dump_file, t, 0);
-       }
-      gimple_stmt_iterator gsi = gsi_for_stmt (t);
-      if (gimple_code (t) == GIMPLE_PHI)
-       remove_phi_node (&gsi, true);
-      else
-       {
-         gsi_remove (&gsi, true);
-         release_defs (t);
-       }
-    }
-}
-
 
 /* Initialize data structures used by PRE.  */
 
@@ -4188,7 +4131,11 @@ pass_pre::execute (function *fun)
   /* Remove all the redundant expressions.  */
   todo |= vn_eliminate (inserted_exprs);
 
-  remove_dead_inserted_code ();
+  /* Because we don't follow exactly the standard PRE algorithm, and decide not
+     to insert PHI nodes sometimes, and because value numbering of casts isn't
+     perfect, we sometimes end up inserting dead code.   This simple DCE-like
+     pass removes any insertions we made that weren't actually used.  */
+  simple_dce_from_worklist (inserted_exprs);
 
   fini_pre ();