Hi,
This patch renames remove_dead_inserted_code to simple_dce_from_worklist, moves
it to tree-ssa-dce.c
and makes it a simple public DCE interface. Bootstrap and test along with loop
interchange. It's required
for interchange pass. Is it OK?
BTW, I will push this along with interchange to branch:
gcc.gnu.org/svn/gcc/branches/gimple-linterchange.
Thanks,
bin
2017-11-27 Bin Cheng <bin.ch...@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.diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c
index a5f0edf..227e55d 100644
--- a/gcc/tree-ssa-dce.c
+++ b/gcc/tree-ssa-dce.c
@@ -1723,3 +1723,56 @@ make_pass_cd_dce (gcc::context *ctxt)
{
return new pass_cd_dce (ctxt);
}
+
+
+/* A cheap DCE interface starting from a seed set of possibly dead stmts. */
+
+void
+simple_dce_from_worklist (bitmap seeds)
+{
+ /* ??? Re-use seeds as worklist not only as initial set. This may end up
+ removing more code as well. If we keep seeds unchanged we could restrict
+ new worklist elements to members of seed. */
+ bitmap worklist = seeds;
+ 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
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 281f100..c19d486 100644
--- 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"
@@ -4038,64 +4039,6 @@ 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. */
@@ -4234,7 +4177,13 @@ pass_pre::execute (function *fun)
clear_expression_ids ();
scev_finalize ();
- 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 ();
loop_optimizer_finalize ();
