control_flow.cc

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#include <map>
#include <utility>
#include <vector>

#include "src/conf/warn.h"
#include "src/globals.h"
#include "src/ir/rule_rank.h"
#include "src/ir/skeleton/path.h"
#include "src/ir/skeleton/skeleton.h"
#include "src/ir/skeleton/way.h"
#include "src/util/u32lim.h"

namespace re2c
{

// We don't need all patterns that cause undefined behaviour.
// We only need some examples, the shorter the better.
// See also note [counting skeleton edges].
void Node::naked_ways (way_t & prefix, std::vector<way_t> & ways, nakeds_t &size)
{
    if (!rule.rank.is_none ())
    {
        return;
    }
    else if (end ())
    {
        ways.push_back (prefix);
        size = size + nakeds_t::from64(prefix.size ());
    }
    else if (loop < 2)
    {
        local_inc _ (loop);
        for (arcsets_t::iterator i = arcsets.begin ();
            i != arcsets.end () && !size.overflow (); ++i)
        {
            prefix.push_back (&i->second);
            i->first->naked_ways (prefix, ways, size);
            prefix.pop_back ();
        }
    }
}

void Skeleton::warn_undefined_control_flow ()
{
    way_t prefix;
    std::vector<way_t> ways;
    Node::nakeds_t size = Node::nakeds_t::from32(0u);

    nodes->naked_ways (prefix, ways, size);

    if (!ways.empty ())
    {
        warn.undefined_control_flow (line, cond, ways, size.overflow ());
    }
    else if (size.overflow ())
    {
        warn.fail (Warn::UNDEFINED_CONTROL_FLOW, line, "DFA is too large to check undefined control flow");
    }
}

} // namespace re2c