Attachment 76242 Details for Bug 43460 – plugin script (with StringBuffer)

plugin script (with StringBuffer)

emptylength.py (text/plain), 4.99 KB, created by Thomas Arnhold on 2013-03-09 20:51:38 UTC

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Creator: Thomas Arnhold

Created: 2013-03-09 20:51:38 UTC

Size: 4.99 KB

patch

obsolete

># Find calls of rtl::O[U]String::getLength() that check for an empty string (and
># that would better use calls to rtl::O[U]String::isEmpty) in the LibreOffice
># code base.
>#
># Emits GCC notes prefixed with "[EmptyLength plugin]".  The re-constructed
># original comparison and the suggested improvement should be taken with a grain
># of salt.
>#
># * See <https://fedorahosted.org/gcc-python-plugin/> for details about the GCC
>#   Python plugin.
>#
># * Requires a recent gcc-python-plugin.git version (post v0.7) including
>#   <http://git.fedorahosted.org/git/?p=gcc-python-plugin.git;a=commit;h=
>#   2bb77306c37bb03a616c2554cfbf25dc02640b43> adding "fullname" support.
>#
># * Can be enabled in a LibreOffice build via
>#
>#   ./autogen.sh ... CXX='g++ -fplugin=</path-to>/gcc-python-plugin/python.so
>#       -fplugin-arg-python-script=</path-to>/emptylength.py'
>#
># * Produces false positives like in (sal/rtl/source/bootstrap.cxx:237):
>#
>#   inline void EnsureNoFinalSlash (rtl::OUString & url)
>#   {
>#       sal_Int32 i = url.getLength();
>#       if (i > 0 && url[i - 1] == '/') {
>#           url = url.copy(0, i - 1);
>#       }
>#   }
>#
>#   sal/rtl/source/bootstrap.cxx:240:5: note: [EmptyLength plugin] replace
>#   "getLength() > 0" with "!isEmpty()"
>#
># * Disable ccache (beware g++ pointing to /usr/lib64/ccache/g++, etc.) if you
>#   want to modify this script and re-run GCC.  Otherwise, your script might not
>#   be re-run.
>
>import gcc
>
>verbose = False
>
>class EmptyLength(gcc.GimplePass):
>    def execute(self, fun):
>        for bb in fun.cfg.basic_blocks:
>            if bb.gimple:
>                processBlock(bb.gimple)
>
>def processBlock(statements):
>    calls = set ()
>    for stmt in statements:
>        verbose and stmt.loc and gcc.inform(stmt.loc, 'XXX stmt: "%s"' % stmt)
>        if isinstance(stmt, gcc.GimpleCall):
>            if isSimpleVar(stmt.lhs) and stmt.fndecl \
>                    and isLength(stmt.fndecl.fullname):
>                verbose and gcc.inform(stmt.loc, 'XXX match call');
>                calls.add(stmt.lhs.addr)
>        elif isinstance(stmt, gcc.GimpleAssign):
>            if len(stmt.rhs) == 1:
>                if isSimpleVar(stmt.lhs) and stmt.exprcode == gcc.VarDecl \
>                        and isCall(calls, stmt.rhs[0]):
>                    verbose and gcc.inform(stmt.loc, 'XXX match assign');
>                    calls.add(stmt.lhs.addr)
>            elif len(stmt.rhs) == 2:
>                verbose and gcc.inform(stmt.loc, 'XXX check assign');
>                checkLength(
>                    stmt.loc, calls, stmt.exprcode, stmt.rhs[0], stmt.rhs[1])
>        elif isinstance(stmt, gcc.GimpleCond):
>            verbose and gcc.inform(stmt.loc, 'XXX check cond');
>            checkLength(stmt.loc, calls, stmt.exprcode, stmt.lhs, stmt.rhs)
>
>def checkLength(location, calls, exprcode, lhs, rhs):
>    if isCall(calls, lhs):
>        if exprcode == gcc.EqExpr and isConst(rhs, 0):
>            replace(location, 'getLength() == 0', 'isEmpty()')
>        elif exprcode == gcc.GeExpr and isConst(rhs, 1):
>            replace(location, 'getLength() >= 1', '!isEmpty()')
>        elif exprcode == gcc.GtExpr and isConst(rhs, 0):
>            replace(location, 'getLength() > 0', '!isEmpty()')
>        elif exprcode == gcc.LeExpr and isConst(rhs, 0):
>            replace(location, 'getLength() <= 0', 'isEmpty()')
>        elif exprcode == gcc.LtExpr and isConst(rhs, 1):
>            replace(location, 'getLength() < 1', 'isEmpty()')
>        elif exprcode == gcc.NeExpr and isConst(rhs, 0):
>            replace(location, 'getLength() != 0', '!isEmpty()')
>    elif isCall(calls, rhs):
>        if exprcode == gcc.EqExpr and isConst(lhs, 0):
>            replace(location, '0 == getLength()', 'isEmpty()')
>        elif exprcode == gcc.GeExpr and isConst(lhs, 0):
>            replace(location, '0 >= getLength()', 'isEmpty()')
>        elif exprcode == gcc.GtExpr and isConst(lhs, 1):
>            replace(location, '1 > getLength()', 'isEmpty()')
>        elif exprcode == gcc.LeExpr and isConst(lhs, 1):
>            replace(location, '1 <= getLength()', '!isEmpty()')
>        elif exprcode == gcc.LtExpr and isConst(lhs, 0):
>            replace(location, '0 < getLength()', '!isEmpty()')
>        elif exprcode == gcc.NeExpr and isConst(lhs, 0):
>            replace(location, '0 != getLength()', '!isEmpty()')
>
>def isLength(fullname):
>    return fullname == 'sal_Int32 rtl::OString::getLength() const' \
>        or fullname == 'sal_Int32 rtl::OUString::getLength() const' \
>        or fullname == 'sal_Int32 rtl::OStringBuffer::getLength() const' \
>        or fullname == 'sal_Int32 rtl::OUStringBuffer::getLength() const';
>
>def isCall(calls, tree):
>    return isSimpleVar(tree) and tree.addr in calls
>
>def isSimpleVar(tree):
>    return isinstance(tree, gcc.VarDecl) and tree.addr
>
>def isConst(tree, value):
>    return isinstance(tree, gcc.Constant) and tree.constant == value
>
>def replace(location, found, better):
>    gcc.inform(
>        location,
>        '[EmptyLength plugin] replace "%s" with "%s"' % (found, better))
>
>ps = EmptyLength(name='EmptyLength')
>ps.register_after('cfg')

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Attachments on bug 43460: 54059 | 54060 | 76242

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