rose: elide SET_GROUPS when possible

src/rose/rose_build_groups.cpp

@@ -0,0 +1,116 @@
+/*
+ * Copyright (c) 2016, Intel Corporation
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *  * Neither the name of Intel Corporation nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * \file
+ * \brief Rose build: code for analysing literal groups.
+ */
+
+#include "rose_build_groups.h"
+
+#include <vector>
+
+#include <boost/graph/topological_sort.hpp>
+#include <boost/range/adaptor/reversed.hpp>
+
+using namespace std;
+
+namespace ue2 {
+
+/**
+ * \brief Returns a mapping from each graph vertex v to the intersection of the
+ * groups switched on by all of the paths leading up to (and including) v from
+ * the start vertexes.
+ */
+unordered_map<RoseVertex, rose_group>
+getVertexGroupMap(const RoseBuildImpl &build) {
+    const RoseGraph &g = build.g;
+    vector<RoseVertex> v_order;
+    v_order.reserve(num_vertices(g));
+
+    boost::topological_sort(g, back_inserter(v_order),
+                            vertex_index_map(get(&RoseVertexProps::idx, g)));
+
+    unordered_map<RoseVertex, rose_group> vertex_group_map;
+    vertex_group_map.reserve(num_vertices(g));
+
+    const rose_group initial_groups = build.getInitialGroups();
+
+    for (const auto &v : boost::adaptors::reverse(v_order)) {
+        DEBUG_PRINTF("vertex %zu\n", g[v].idx);
+
+        if (build.isAnyStart(v)) {
+            DEBUG_PRINTF("start vertex, groups=0x%llx\n", initial_groups);
+            vertex_group_map.emplace(v, initial_groups);
+            continue;
+        }
+
+        // To get to this vertex, we must have come through a predecessor, and
+        // everyone who isn't a start vertex has one.
+        assert(in_degree(v, g) > 0);
+        rose_group pred_groups = ~rose_group{0};
+        for (auto u : inv_adjacent_vertices_range(v, g)) {
+            DEBUG_PRINTF("pred %zu\n", g[u].idx);
+            assert(contains(vertex_group_map, u));
+            pred_groups &= vertex_group_map.at(u);
+        }
+
+        DEBUG_PRINTF("pred_groups=0x%llx\n", pred_groups);
+        DEBUG_PRINTF("g[v].groups=0x%llx\n", g[v].groups);
+
+        rose_group v_groups = pred_groups | g[v].groups;
+        DEBUG_PRINTF("v_groups=0x%llx\n", v_groups);
+
+        vertex_group_map.emplace(v, v_groups);
+    }
+
+    return vertex_group_map;
+}
+
+/**
+ * \brief Find the set of groups that can be squashed anywhere in the graph,
+ * either by a literal or by a leftfix.
+ */
+rose_group getSquashableGroups(const RoseBuildImpl &build) {
+    rose_group squashable_groups = 0;
+    for (const auto &info : build.literal_info) {
+        if (info.squash_group) {
+            DEBUG_PRINTF("lit squash mask 0x%llx\n", info.group_mask);
+            squashable_groups |= info.group_mask;
+        }
+    }
+    for (const auto &m : build.rose_squash_masks) {
+        DEBUG_PRINTF("left squash mask 0x%llx\n", ~m.second);
+        squashable_groups |= ~m.second;
+    }
+
+    DEBUG_PRINTF("squashable groups=0x%llx\n", squashable_groups);
+    return squashable_groups;
+}
+
+} // namespace ue2