From dd907febac3e4371eaa7610064db47ecb9922368 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Bylica?= <chfast@gmail.com>
Date: Wed, 19 May 2021 11:20:19 +0200
Subject: [PATCH] squash! Support all depths in Histogram

---
 lib/evmone/tracing.cpp          | 61 +++++++++++++++++++--------------
 test/integration/CMakeLists.txt |  2 +-
 test/unittests/tracing_test.cpp | 14 ++++++--
 3 files changed, 47 insertions(+), 30 deletions(-)

diff --git a/lib/evmone/tracing.cpp b/lib/evmone/tracing.cpp
index 497b060f0a..63cbd3d740 100644
--- a/lib/evmone/tracing.cpp
+++ b/lib/evmone/tracing.cpp
@@ -4,52 +4,61 @@
 
 #include "tracing.hpp"
 #include <evmc/hex.hpp>
+#include <stack>
 
 namespace evmone
 {
 namespace
 {
+std::string get_name(const char* const* names, uint8_t opcode)
+{
+    const auto name = names[opcode];
+    return (name != nullptr) ? name : "0x" + evmc::hex(opcode);
+}
+
 /// @see create_histogram_tracer()
 class HistogramTracer : public Tracer
 {
-    const uint8_t* m_code = nullptr;
-    int32_t m_depth = -1;
-    const char* const* m_opcode_names = nullptr;
-    uint32_t m_counts[256]{};
+    struct Context
+    {
+        const int32_t depth;
+        const uint8_t* const code;
+        const char* const* const opcode_names;
+        uint32_t counts[256]{};
+
+        Context(int32_t _depth, const uint8_t* _code, const char* const* _opcode_names) noexcept
+          : depth{_depth}, code{_code}, opcode_names{_opcode_names}
+        {}
+    };
+
+    std::stack<Context> m_contexts;
     std::ostream& m_out;
 
     void on_execution_start(
         evmc_revision rev, const evmc_message& msg, bytes_view code) noexcept override
     {
-        m_code = code.data();
-        m_depth = msg.depth;
-        if (m_depth == 0)
-            m_opcode_names = evmc_get_instruction_names_table(rev);
+        m_contexts.emplace(msg.depth, code.data(), evmc_get_instruction_names_table(rev));
     }
 
-    void on_instruction_start(uint32_t pc) noexcept override { ++m_counts[m_code[pc]]; }
+    void on_instruction_start(uint32_t pc) noexcept override
+    {
+        auto& ctx = m_contexts.top();
+        ++ctx.counts[ctx.code[pc]];
+    }
 
     void on_execution_end(const evmc_result& /*result*/) noexcept override
     {
-        if (m_depth == 0)
-        {
-            m_out << "--- # HISTOGRAM\nopcode,count\n";
-            for (size_t i = 0; i < std::size(m_counts); ++i)
-            {
-                if (m_counts[i] != 0)
-                {
-                    if (const auto name = m_opcode_names[i]; name != nullptr)
-                        m_out << name;
-                    else
-                        m_out << "0x" << evmc::hex(static_cast<uint8_t>(i));
-                    m_out << ',' << m_counts[i] << '\n';
-                }
-            }
+        const auto& ctx = m_contexts.top();
+        const auto names = ctx.opcode_names;
 
-            m_opcode_names = nullptr;
-            m_depth = -1;
-            m_code = nullptr;
+        m_out << "--- # HISTOGRAM depth=" << ctx.depth << "\nopcode,count\n";
+        for (size_t i = 0; i < std::size(ctx.counts); ++i)
+        {
+            if (ctx.counts[i] != 0)
+                m_out << get_name(names, static_cast<uint8_t>(i)) << ',' << ctx.counts[i] << '\n';
         }
+
+        m_contexts.pop();
     }
 
 public:
diff --git a/test/integration/CMakeLists.txt b/test/integration/CMakeLists.txt
index a6ac815911..6d26d4a664 100644
--- a/test/integration/CMakeLists.txt
+++ b/test/integration/CMakeLists.txt
@@ -10,7 +10,7 @@ if(EVMONE_LIB_TYPE STREQUAL SHARED_LIBRARY)
     add_test(NAME ${PREFIX}/histogram COMMAND $<TARGET_FILE:evmc::tool> --vm $<TARGET_FILE:evmone>,O=0,histogram run 6000808080800101010200)
     set_tests_properties(
         ${PREFIX}/histogram PROPERTIES PASS_REGULAR_EXPRESSION
-        "--- # HISTOGRAM
+        "--- # HISTOGRAM depth=0
 opcode,count
 STOP,1
 ADD,3
diff --git a/test/unittests/tracing_test.cpp b/test/unittests/tracing_test.cpp
index 8f292f9cb5..018d54b015 100644
--- a/test/unittests/tracing_test.cpp
+++ b/test/unittests/tracing_test.cpp
@@ -103,7 +103,7 @@ TEST_F(tracing, histogram)
 
     trace_stream << '\n';
     EXPECT_EQ(trace(add(0, 0)), R"(
---- # HISTOGRAM
+--- # HISTOGRAM depth=0
 opcode,count
 ADD,1
 PUSH1,2
@@ -116,7 +116,7 @@ TEST_F(tracing, histogram_undefined_instruction)
 
     trace_stream << '\n';
     EXPECT_EQ(trace(bytecode{"EF"}), R"(
---- # HISTOGRAM
+--- # HISTOGRAM depth=0
 opcode,count
 0xef,1
 )");
@@ -125,5 +125,13 @@ opcode,count
 TEST_F(tracing, histogram_internal_call)
 {
     vm.add_tracer(evmone::create_histogram_tracer(trace_stream));
-    EXPECT_EQ(trace(add(0, 0), 1), "");  // No output on depth=1.
+    trace_stream << '\n';
+    EXPECT_EQ(trace(push(0) + OP_DUP1 + OP_SWAP1 + OP_POP + OP_POP, 1), R"(
+--- # HISTOGRAM depth=1
+opcode,count
+POP,2
+PUSH1,1
+DUP1,1
+SWAP1,1
+)");
 }