Merge pull request #10771 from TryTwo/PR_AutoStep

Debugger: Implement base code tracing logic. and feature to auto-step through code.

Source/Core/Common/CMakeLists.txt

@@ -33,6 +33,8 @@ add_library(common
   Crypto/ec.h
   Crypto/SHA1.cpp
   Crypto/SHA1.h
+  Debug/CodeTrace.cpp
+  Debug/CodeTrace.h
   Debug/MemoryPatches.cpp
   Debug/MemoryPatches.h
   Debug/Threads.h

Source/Core/Common/Debug/CodeTrace.cpp

@@ -0,0 +1,389 @@
+// Copyright 2022 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "Common/Debug/CodeTrace.h"
+
+#include <chrono>
+#include <regex>
+
+#include "Common/Event.h"
+#include "Common/StringUtil.h"
+#include "Core/Debugger/PPCDebugInterface.h"
+#include "Core/HW/CPU.h"
+#include "Core/PowerPC/PowerPC.h"
+
+namespace
+{
+bool IsInstructionLoadStore(std::string_view ins)
+{
+  return (StringBeginsWith(ins, "l") && !StringBeginsWith(ins, "li")) ||
+         StringBeginsWith(ins, "st") || StringBeginsWith(ins, "psq_l") ||
+         StringBeginsWith(ins, "psq_s");
+}
+
+u32 GetMemoryTargetSize(std::string_view instr)
+{
+  // Word-size operations are taken as the default, check the others.
+  auto op = instr.substr(0, 4);
+
+  constexpr char BYTE_TAG = 'b';
+  constexpr char HALF_TAG = 'h';
+  constexpr char DOUBLE_WORD_TAG = 'd';
+  constexpr char PAIRED_TAG = 'p';
+
+  // Actual range is 0 to size - 1;
+  if (op.find(BYTE_TAG) != std::string::npos)
+  {
+    return 1;
+  }
+  else if (op.find(HALF_TAG) != std::string::npos)
+  {
+    return 2;
+  }
+  else if (op.find(DOUBLE_WORD_TAG) != std::string::npos ||
+           op.find(PAIRED_TAG) != std::string::npos)
+  {
+    return 8;
+  }
+
+  return 4;
+}
+}  // namespace
+
+void CodeTrace::SetRegTracked(const std::string& reg)
+{
+  m_reg_autotrack.push_back(reg);
+}
+
+InstructionAttributes CodeTrace::GetInstructionAttributes(const TraceOutput& instruction) const
+{
+  // Slower process of breaking down saved instruction. Only used when stepping through code if a
+  // decision has to be made, otherwise used afterwards on a log file.
+  InstructionAttributes tmp_attributes;
+  tmp_attributes.instruction = instruction.instruction;
+  tmp_attributes.address = PC;
+  std::string instr = instruction.instruction;
+  std::smatch match;
+
+  // Convert sp, rtoc, and ps to r1, r2, and F#. ps is handled like a float operation.
+  static const std::regex replace_sp("(\\W)sp");
+  instr = std::regex_replace(instr, replace_sp, "$1r1");
+  static const std::regex replace_rtoc("rtoc");
+  instr = std::regex_replace(instr, replace_rtoc, "r2");
+  static const std::regex replace_ps("(\\W)p(\\d+)");
+  instr = std::regex_replace(instr, replace_ps, "$1f$2");
+
+  // Pull all register numbers out and store them. Limited to Reg0 if ps operation, as ps get
+  // too complicated to track easily.
+  // ex: add r4, r5, r6 -> r4 = Reg0, r5 = Reg1, r6 = Reg2. Reg0 is always the target register.
+  static const std::regex regis(
+      "\\W([rfp]\\d+)[^r^f]*(?:([rf]\\d+))?[^r^f\\d]*(?:([rf]\\d+))?[^r^f\\d]*(?:([rf]\\d+))?",
+      std::regex::optimize);
+
+  if (std::regex_search(instr, match, regis))
+  {
+    tmp_attributes.reg0 = match.str(1);
+    if (match[2].matched)
+      tmp_attributes.reg1 = match.str(2);
+    if (match[3].matched)
+      tmp_attributes.reg2 = match.str(3);
+    if (match[4].matched)
+      tmp_attributes.reg3 = match.str(4);
+
+    if (instruction.memory_target)
+    {
+      tmp_attributes.memory_target = instruction.memory_target;
+      tmp_attributes.memory_target_size = GetMemoryTargetSize(instr);
+
+      if (StringBeginsWith(instr, "st") || StringBeginsWith(instr, "psq_s"))
+        tmp_attributes.is_store = true;
+      else
+        tmp_attributes.is_load = true;
+    }
+  }
+
+  return tmp_attributes;
+}
+
+TraceOutput CodeTrace::SaveCurrentInstruction() const
+{
+  // Quickly save instruction and memory target for fast logging.
+  TraceOutput output;
+  const std::string instr = PowerPC::debug_interface.Disassemble(PC);
+  output.instruction = instr;
+  output.address = PC;
+
+  if (IsInstructionLoadStore(output.instruction))
+    output.memory_target = PowerPC::debug_interface.GetMemoryAddressFromInstruction(instr);
+
+  return output;
+}
+
+bool CompareMemoryTargetToTracked(const std::string& instr, const u32 mem_target,
+                                  const std::set<u32>& mem_tracked)
+{
+  // This function is hit often and should be optimized.
+  auto it_lower = std::lower_bound(mem_tracked.begin(), mem_tracked.end(), mem_target);
+
+  if (it_lower == mem_tracked.end())
+    return false;
+  else if (*it_lower == mem_target)
+    return true;
+
+  // If the base value doesn't hit, still need to check if longer values overlap.
+  return *it_lower < mem_target + GetMemoryTargetSize(instr);
+}
+
+AutoStepResults CodeTrace::AutoStepping(bool continue_previous, AutoStop stop_on)
+{
+  AutoStepResults results;
+
+  if (!CPU::IsStepping() || m_recording)
+    return results;
+
+  TraceOutput pc_instr = SaveCurrentInstruction();
+  const InstructionAttributes instr = GetInstructionAttributes(pc_instr);
+
+  // Not an instruction we should start autostepping from (ie branches).
+  if (instr.reg0.empty() && !continue_previous)
+    return results;
+
+  m_recording = true;
+
+  // Once autostep stops, it can be told to continue running without resetting the tracked
+  // registers and memory.
+  if (!continue_previous)
+  {
+    m_reg_autotrack.clear();
+    m_mem_autotrack.clear();
+    m_reg_autotrack.push_back(instr.reg0);
+
+    // It wouldn't necessarily be wrong to also record the memory of a load operation, as the
+    // value exists there too. May or may not be desirable depending on task. Leaving it out.
+    if (instr.is_store)
+    {
+      const u32 size = GetMemoryTargetSize(instr.instruction);
+      for (u32 i = 0; i < size; i++)
+        m_mem_autotrack.insert(instr.memory_target.value() + i);
+    }
+  }
+
+  // Count is important for feedback on how much work was done.
+
+  HitType hit = HitType::SKIP;
+  HitType stop_condition = HitType::SAVELOAD;
+
+  // Could use bit flags, but I organized it to have decreasing levels of verbosity, so the
+  // less-than comparison ignores what is needed for the current usage.
+  if (stop_on == AutoStop::Always)
+    stop_condition = HitType::SAVELOAD;
+  else if (stop_on == AutoStop::Used)
+    stop_condition = HitType::PASSIVE;
+  else if (stop_on == AutoStop::Changed)
+    stop_condition = HitType::ACTIVE;
+
+  CPU::PauseAndLock(true, false);
+  PowerPC::breakpoints.ClearAllTemporary();
+  using clock = std::chrono::steady_clock;
+  clock::time_point timeout = clock::now() + std::chrono::seconds(4);
+
+  PowerPC::CoreMode old_mode = PowerPC::GetMode();
+  PowerPC::SetMode(PowerPC::CoreMode::Interpreter);
+
+  do
+  {
+    PowerPC::SingleStep();
+
+    pc_instr = SaveCurrentInstruction();
+    hit = TraceLogic(pc_instr);
+    results.count += 1;
+  } while (clock::now() < timeout && hit < stop_condition &&
+           !(m_reg_autotrack.empty() && m_mem_autotrack.empty()));
+
+  // Report the timeout to the caller.
+  if (clock::now() >= timeout)
+    results.timed_out = true;
+
+  PowerPC::SetMode(old_mode);
+  CPU::PauseAndLock(false, false);
+  m_recording = false;
+
+  results.reg_tracked = m_reg_autotrack;
+  results.mem_tracked = m_mem_autotrack;
+
+  // Doesn't currently need to report the hit type to the caller. Denoting when the reg and mem
+  // trackers are both empty is important, as it means our target was overwritten and can no longer
+  // be tracked. Different actions can be taken on a timeout vs empty trackers, so they are reported
+  // individually.
+  return results;
+}
+
+HitType CodeTrace::TraceLogic(const TraceOutput& current_instr, bool first_hit)
+{
+  // Tracks the original value that is in the targeted register or memory through loads, stores,
+  // register moves, and value changes. Also finds when it is used. ps operations are not fully
+  // supported. -ux memory instructions may need special cases.
+  // Should not be called if reg and mem tracked are empty.
+
+  // Using a std::set because it can easily insert the memory range being accessed without
+  // causing duplicates, and quickly erases all members of the memory range without caring if the
+  // element actually exists.
+
+  bool mem_hit = false;
+  if (current_instr.memory_target && !m_mem_autotrack.empty())
+  {
+    mem_hit = CompareMemoryTargetToTracked(current_instr.instruction, *current_instr.memory_target,
+                                           m_mem_autotrack);
+  }
+
+  // Optimization for tracking a memory target when no registers are being tracked.
+  if (m_reg_autotrack.empty() && !mem_hit)
+    return HitType::SKIP;
+
+  // Break instruction down into parts to be analyzed.
+  const InstructionAttributes instr = GetInstructionAttributes(current_instr);
+
+  // Not an instruction we care about (branches).
+  if (instr.reg0.empty())
+    return HitType::SKIP;
+
+  // The reg_itr will be used later for erasing.
+  auto reg_itr = std::find(m_reg_autotrack.begin(), m_reg_autotrack.end(), instr.reg0);
+  const bool match_reg123 =
+      (!instr.reg1.empty() && std::find(m_reg_autotrack.begin(), m_reg_autotrack.end(),
+                                        instr.reg1) != m_reg_autotrack.end()) ||
+      (!instr.reg2.empty() && std::find(m_reg_autotrack.begin(), m_reg_autotrack.end(),
+                                        instr.reg2) != m_reg_autotrack.end()) ||
+      (!instr.reg3.empty() && std::find(m_reg_autotrack.begin(), m_reg_autotrack.end(),
+                                        instr.reg3) != m_reg_autotrack.end());
+  const bool match_reg0 = reg_itr != m_reg_autotrack.end();
+
+  if (!match_reg0 && !match_reg123 && !mem_hit)
+    return HitType::SKIP;
+
+  // Checks if the intstruction is a type that needs special handling.
+  const auto CompareInstruction = [](std::string_view instruction, const auto& type_compare) {
+    return std::any_of(
+        type_compare.begin(), type_compare.end(),
+        [&instruction](std::string_view s) { return StringBeginsWith(instruction, s); });
+  };
+
+  // Exclusions from updating tracking logic. mt operations are too complex and specialized.
+  // Combiner used later.
+  static const std::array<std::string_view, 3> exclude{"dc", "ic", "mt"};
+  static const std::array<std::string_view, 2> compare{"c", "fc"};
+
+  // rlwimi, at least, can preserve parts of the target register. Not sure if rldimi can too or if
+  // there are any others like this.
+  static const std::array<std::string_view, 1> combiner{"rlwimi"};
+
+  static const std::array<std::string_view, 2> mover{"mr", "fmr"};
+
+  // Link register for when r0 gets overwritten
+  if (StringBeginsWith(instr.instruction, "mflr") && match_reg0)
+  {
+    m_reg_autotrack.erase(reg_itr);
+    return HitType::OVERWRITE;
+  }
+  else if (StringBeginsWith(instr.instruction, "mtlr") && match_reg0)
+  {
+    // LR is not something tracked
+    return HitType::MOVED;
+  }
+
+  if (CompareInstruction(instr.instruction, exclude))
+    return HitType::SKIP;
+  else if (CompareInstruction(instr.instruction, compare))
+    return HitType::PASSIVE;
+  else if (match_reg123 && !match_reg0 && (instr.is_store || instr.is_load))
+    return HitType::POINTER;
+
+  // Update tracking logic. At this point a memory or register hit happened.
+  // Save/Load
+  if (instr.memory_target)
+  {
+    if (mem_hit)
+    {
+      // If hit a tracked memory. Load -> Add register to tracked.  Store -> Remove tracked memory
+      // if overwritten.
+
+      if (instr.is_load && !match_reg0)
+      {
+        m_reg_autotrack.push_back(instr.reg0);
+        return HitType::SAVELOAD;
+      }
+      else if (instr.is_store && !match_reg0)
+      {
+        // On First Hit it wouldn't necessarily be wrong to track the register, which contains the
+        // same value. A matter of preference.
+        if (first_hit)
+          return HitType::SAVELOAD;
+
+        for (u32 i = 0; i < instr.memory_target_size; i++)
+          m_mem_autotrack.erase(*instr.memory_target + i);
+
+        return HitType::OVERWRITE;
+      }
+      else
+      {
+        // If reg0 and store/load are both already tracked, do nothing.
+        return HitType::SAVELOAD;
+      }
+    }
+    else if (instr.is_store && match_reg0)
+    {
+      // If store to untracked memory, then track memory.
+      for (u32 i = 0; i < instr.memory_target_size; i++)
+        m_mem_autotrack.insert(*instr.memory_target + i);
+
+      return HitType::SAVELOAD;
+    }
+    else if (instr.is_load && match_reg0)
+    {
+      // Not wrong to track load memory_target here. Preference.
+      if (first_hit)
+        return HitType::SAVELOAD;
+
+      // If untracked load is overwriting tracked register, then remove register
+      m_reg_autotrack.erase(reg_itr);
+      return HitType::OVERWRITE;
+    }
+  }
+  else if (!match_reg0 && !match_reg123)
+  {
+    // Skip if no matches. Happens most often.
+    return HitType::SKIP;
+  }
+  else
+  {
+    // If tracked register data is being stored in a new register, save new register.
+    if (match_reg123 && !match_reg0)
+    {
+      m_reg_autotrack.push_back(instr.reg0);
+
+      // This should include any instruction that can reach this point and is not ACTIVE. Can only
+      // think of mr at this time.
+      if (CompareInstruction(instr.instruction, mover))
+        return HitType::MOVED;
+
+      return HitType::ACTIVE;
+    }
+    // If tracked register is overwritten, stop tracking.
+    else if (match_reg0 && !match_reg123)
+    {
+      if (CompareInstruction(instr.instruction, combiner) || first_hit)
+        return HitType::UPDATED;
+
+      m_reg_autotrack.erase(reg_itr);
+      return HitType::OVERWRITE;
+    }
+    else if (match_reg0 && match_reg123)
+    {
+      // Or moved
+      return HitType::UPDATED;
+    }
+  }
+
+  // Should not reach this
+  return HitType::SKIP;
+}