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parser - push normalize_tree() ops into expr-tree classes

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This is patch tries to reduce the number of dynamic_cast<>s needed
during normalization by pushing the operations of normalize_tree()
into the expr-tree classes themselves rather than perform it as
an external function. This eliminates the need for dynamic_cast<>
checks on the current object under inspection and reduces the number
of checks needing to be performed on child Nodes as well.

In non-strict benchmarking, doing the dynamic_cast<> reduction
for just the tree normalization operation resulted in a ~10-15%
improvement in overall time on a couple of different hosts (amd64,
armel), as measured against apparmor_parser -Q.  Valgrind's callgrind
tool indicated a reduction in the number of calls to dynamic_cast<>
on the tst/simple_tests/vars/dbus_vars_9.sd test profile from ~19
million calls to ~12 million.

In comparisons with dumped expr trees over both the entire
tst/simple_tests/ tree and from 1000 randomly generated profiles via
stress.rb, the generated trees were identical.

Patch history:
  v1: initial version of patch
  v2: update patch to take into account the infinite loop fix in
      trunk rev 1975 and refresh against current code.
  v3: no change

Signed-off-by: Steve Beattie <steve@nxnw.org>
Acked-by: Seth Arnold <seth.arnold@canonical.com>
Acked-by: John Johansen <john.johansen@canonical.com>
This commit is contained in:
Steve Beattie
2013-11-28 00:43:35 -08:00
parent fb33689ec3
commit 0e09546391
2 changed files with 74 additions and 41 deletions
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15
parser/libapparmor_re/expr-tree.h
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@@ -1,7 +1,7 @@
/*
* (C) 2006, 2007 Andreas Gruenbacher <agruen@suse.de>
* Copyright (c) 2003-2008 Novell, Inc. (All rights reserved)
* Copyright 2009-2012 Canonical Ltd.
* Copyright 2009-2013 Canonical Ltd.
*
* The libapparmor library is licensed under the terms of the GNU
* Lesser General Public License, version 2.1. Please see the file
@@ -126,6 +126,15 @@ public:
virtual int eq(Node *other) = 0;
virtual ostream &dump(ostream &os) = 0;
void dump_syntax_tree(ostream &os);
virtual void normalize(int dir)
{
if (child[dir])
child[dir]->normalize(dir);
if (child[!dir])
child[!dir]->normalize(dir);
}
/* return false if no work done */
virtual int normalize_eps(int dir __attribute__((unused))) { return 0; }
bool nullable;
NodeSet firstpos, lastpos, followpos;
@@ -157,11 +166,13 @@ public:
class TwoChildNode: public InnerNode {
public:
TwoChildNode(Node *left, Node *right): InnerNode(left, right) { };
virtual int normalize_eps(int dir);
};
class LeafNode: public Node {
public:
LeafNode(): Node() { };
virtual void normalize(int dir __attribute__((unused))) { return; }
};
/* Match nothing (//). */
@@ -485,6 +496,7 @@ public:
child[1]->dump(os);
return os;
}
void normalize(int dir);
};
/* Match one of two alternative nodes. */
@@ -521,6 +533,7 @@ public:
os << ')';
return os;
}
void normalize(int dir);
};
/* Traverse the syntax tree depth-first in an iterator-like manner. */