ProfileViewer: Add an instruction-level sample viewer

When you select a function in the profile tree, we will now display
a per-instruction breakdown of aggregated samples in that function.

This allows us to look much closer at what our code is doing! :^)

DevTools/ProfileViewer/DisassemblyModel.cpp

@@ -0,0 +1,131 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. 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.
+ *
+ * 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 HOLDER 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.
+ */
+
+#include "DisassemblyModel.h"
+#include "Profile.h"
+#include <AK/MappedFile.h>
+#include <LibELF/ELFLoader.h>
+#include <LibX86/Disassembler.h>
+#include <ctype.h>
+#include <stdio.h>
+
+DisassemblyModel::DisassemblyModel(Profile& profile, ProfileNode& node)
+    : m_profile(profile)
+    , m_node(node)
+{
+    m_file = make<MappedFile>(profile.executable_path());
+    auto elf_loader = make<ELFLoader>((const u8*)m_file->data(), m_file->size());
+
+    auto symbol = elf_loader->find_symbol(node.address());
+    ASSERT(symbol.has_value());
+
+    auto view = symbol.value().raw_data();
+    X86::SimpleInstructionStream stream((const u8*)view.characters_without_null_termination(), view.length());
+    X86::Disassembler disassembler(stream);
+
+    dbg() << "Disassembly for " << node.symbol() << " @ " << (const void*)node.address();
+
+    size_t offset_into_symbol = 0;
+    for (;;) {
+        auto insn = disassembler.next();
+        if (!insn.has_value())
+            break;
+        FlatPtr address_in_profiled_program = symbol.value().value() + offset_into_symbol;
+
+        auto disassembly = insn.value().to_string(address_in_profiled_program);
+        dbg() << disassembly;
+
+        StringView instruction_bytes = view.substring_view(offset_into_symbol, insn.value().length());
+        size_t samples_at_this_instruction = m_node.events_per_address().get(address_in_profiled_program).value_or(0);
+
+        m_instructions.append({ insn.value(), disassembly, instruction_bytes, address_in_profiled_program, samples_at_this_instruction });
+
+        offset_into_symbol += insn.value().length();
+    }
+}
+
+DisassemblyModel::~DisassemblyModel()
+{
+}
+
+int DisassemblyModel::row_count(const GUI::ModelIndex&) const
+{
+    return m_instructions.size();
+}
+
+String DisassemblyModel::column_name(int column) const
+{
+    switch (column) {
+    case Column::SampleCount:
+        return m_profile.show_percentages() ? "% Samples" : "# Samples";
+    case Column::Address:
+        return "Address";
+    case Column::InstructionBytes:
+        return "Insn Bytes";
+    case Column::Disassembly:
+        return "Disassembly";
+    default:
+        ASSERT_NOT_REACHED();
+        return {};
+    }
+}
+
+GUI::Model::ColumnMetadata DisassemblyModel::column_metadata(int column) const
+{
+    if (column == Column::SampleCount)
+        return ColumnMetadata { 0, Gfx::TextAlignment::CenterRight };
+    return {};
+}
+
+GUI::Variant DisassemblyModel::data(const GUI::ModelIndex& index, Role role) const
+{
+    auto& insn = m_instructions[index.row()];
+    if (role == Role::Display) {
+        if (index.column() == Column::SampleCount) {
+            if (m_profile.show_percentages())
+                return ((float)insn.event_count / (float)m_profile.filtered_event_count()) * 100.0f;
+            return insn.event_count;
+        }
+        if (index.column() == Column::Address)
+            return String::format("%#08x", insn.address);
+        if (index.column() == Column::InstructionBytes) {
+            StringBuilder builder;
+            for (auto ch : insn.bytes) {
+                builder.appendf("%02x ", (u8)ch);
+            }
+            return builder.to_string();
+        }
+        if (index.column() == Column::Disassembly)
+            return insn.disassembly;
+        return {};
+    }
+    return {};
+}
+
+void DisassemblyModel::update()
+{
+    did_update();
+}