Merge pull request #80 from ethereum/jump

Speed up finding jumpdests

Author: chfast

lib/evmone/analysis.cpp

@@ -17,17 +17,6 @@ bool is_terminator(uint8_t c) noexcept
 }
 }  // namespace
 
-int code_analysis::find_jumpdest(int offset) const noexcept
-{
-    // TODO: Replace with lower_bound().
-    for (const auto& d : jumpdest_map)
-    {
-        if (d.first == offset)
-            return d.second;
-    }
-    return -1;
-}
-
 evmc_call_kind op2call_kind(uint8_t opcode) noexcept
 {
     switch (opcode)
@@ -76,7 +65,10 @@ code_analysis analyze(
             beginblock_instr.arg.p.number = static_cast<int>(analysis.blocks.size() - 1);
 
             if (jumpdest)  // Add the jumpdest to the map.
-                analysis.jumpdest_map.emplace_back(static_cast<int>(i), instr_index);
+            {
+                analysis.jumpdest_offsets.emplace_back(static_cast<int16_t>(i));
+                analysis.jumpdest_targets.emplace_back(static_cast<int16_t>(instr_index));
+            }
             else  // Increase instruction count because additional BEGINBLOCK was injected.
                 ++instr_index;
         }

lib/evmone/analysis.hpp

@@ -152,12 +152,25 @@ struct code_analysis
     /// invalidated when the container grows.
     std::deque<bytes32> args_storage;
 
-    std::vector<std::pair<int, int>> jumpdest_map;
-
-    // TODO: Exported for unit tests. Rework unit tests?
-    EVMC_EXPORT int find_jumpdest(int offset) const noexcept;
+    /// The offsets of JUMPDESTs in the original code.
+    /// These are values that JUMP/JUMPI receives as an argument.
+    /// The elements are sorted.
+    std::vector<int16_t> jumpdest_offsets;
+
+    /// The indexes of the instructions in the generated instruction table
+    /// matching the elements from jumdest_offsets.
+    /// This is value to which the next instruction pointer must be set in JUMP/JUMPI.
+    std::vector<int16_t> jumpdest_targets;
 };
 
+inline int find_jumpdest(const code_analysis& analysis, int offset) noexcept
+{
+    const auto begin = std::begin(analysis.jumpdest_offsets);
+    const auto end = std::end(analysis.jumpdest_offsets);
+    const auto it = std::lower_bound(begin, end, offset);
+    return (it != end && *it == offset) ? analysis.jumpdest_targets[it - begin] : -1;
+}
+
 EVMC_EXPORT code_analysis analyze(
     const exec_fn_table& fns, evmc_revision rev, const uint8_t* code, size_t code_size) noexcept;
 

lib/evmone/instructions.cpp

@@ -481,7 +481,7 @@ void op_jump(execution_state& state, instr_argument) noexcept
     const auto dst = state.stack.pop();
     auto pc = -1;
     if (std::numeric_limits<int>::max() < dst ||
-        (pc = state.analysis->find_jumpdest(static_cast<int>(dst))) < 0)
+        (pc = find_jumpdest(*state.analysis, static_cast<int>(dst))) < 0)
         return state.exit(EVMC_BAD_JUMP_DESTINATION);
 
     state.next_instr = &state.analysis->instrs[static_cast<size_t>(pc)];

test/unittests/analysis_test.cpp

@@ -86,10 +86,13 @@ TEST(analysis, jump1)
     const auto analysis = analyze(fake_fn_table, rev, &code[0], code.size());
 
     ASSERT_EQ(analysis.blocks.size(), 3);
-    ASSERT_EQ(analysis.jumpdest_map.size(), 1);
-    EXPECT_EQ(analysis.jumpdest_map[0], std::pair(6, 5));
-    EXPECT_EQ(analysis.find_jumpdest(6), 5);
-    EXPECT_EQ(analysis.find_jumpdest(0), -1);
+    ASSERT_EQ(analysis.jumpdest_offsets.size(), 1);
+    ASSERT_EQ(analysis.jumpdest_targets.size(), 1);
+    EXPECT_EQ(analysis.jumpdest_offsets[0], 6);
+    EXPECT_EQ(analysis.jumpdest_targets[0], 5);
+    EXPECT_EQ(find_jumpdest(analysis, 6), 5);
+    EXPECT_EQ(find_jumpdest(analysis, 0), -1);
+    EXPECT_EQ(find_jumpdest(analysis, 7), -1);
 }
 
 TEST(analysis, empty)
@@ -108,8 +111,10 @@ TEST(analysis, only_jumpdest)
     auto analysis = evmone::analyze(fake_fn_table, rev, &code[0], code.size());
 
     ASSERT_EQ(analysis.blocks.size(), 1);
-    ASSERT_EQ(analysis.jumpdest_map.size(), 1);
-    EXPECT_EQ(analysis.jumpdest_map[0], std::pair(0, 0));
+    ASSERT_EQ(analysis.jumpdest_offsets.size(), 1);
+    ASSERT_EQ(analysis.jumpdest_targets.size(), 1);
+    EXPECT_EQ(analysis.jumpdest_offsets[0], 0);
+    EXPECT_EQ(analysis.jumpdest_targets[0], 0);
 }
 
 TEST(analysis, jumpi_at_the_end)

test/utils/dump.cpp

@@ -30,14 +30,14 @@ void dump_analysis(const evmone::code_analysis& analysis)
         {
             block = &analysis.blocks[size_t(instr.arg.p.number)];
 
-            auto get_jumpdest_offset = [&analysis](size_t index) noexcept
+            const auto get_jumpdest_offset = [&analysis](size_t index) noexcept
             {
-                for (const auto& d : analysis.jumpdest_map)
+                for (size_t t = 0; t < analysis.jumpdest_targets.size(); ++t)
                 {
-                    if (d.second == static_cast<int>(index))
-                        return d.first;
+                    if (t == index)
+                        return analysis.jumpdest_offsets[t];
                 }
-                return -1;
+                return int16_t{-1};
             };
 
             std::cout << "┌ ";