Merge pull request #11015 from TryTwo/Conditional_Breakpoints

Conditional breakpoints

Source/Core/Core/CMakeLists.txt

@@ -449,6 +449,8 @@ add_library(core
   PowerPC/CachedInterpreter/InterpreterBlockCache.h
   PowerPC/ConditionRegister.cpp
   PowerPC/ConditionRegister.h
+  PowerPC/Expression.cpp
+  PowerPC/Expression.h
   PowerPC/Interpreter/ExceptionUtils.h
   PowerPC/Interpreter/Interpreter_Branch.cpp
   PowerPC/Interpreter/Interpreter_FloatingPoint.cpp
@@ -593,6 +595,7 @@ PUBLIC
   cubeb
   discio
   enet
+  expr
   inputcommon
   ${MBEDTLS_LIBRARIES}
   pugixml

Source/Core/Core/PowerPC/BreakPoints.cpp

@@ -13,6 +13,7 @@
 #include "Common/DebugInterface.h"
 #include "Common/Logging/Log.h"
 #include "Core/Core.h"
+#include "Core/PowerPC/Expression.h"
 #include "Core/PowerPC/JitInterface.h"
 #include "Core/PowerPC/MMU.h"
 
@@ -35,17 +36,16 @@ bool BreakPoints::IsTempBreakPoint(u32 address) const
   });
 }
 
-bool BreakPoints::IsBreakPointBreakOnHit(u32 address) const
+const TBreakPoint* BreakPoints::GetBreakpoint(u32 address) const
 {
-  return std::any_of(m_breakpoints.begin(), m_breakpoints.end(), [address](const auto& bp) {
-    return bp.address == address && bp.break_on_hit;
+  auto bp = std::find_if(m_breakpoints.begin(), m_breakpoints.end(), [address](const auto& bp) {
+    return bp.is_enabled && bp.address == address;
   });
-}
 
-bool BreakPoints::IsBreakPointLogOnHit(u32 address) const
-{
-  return std::any_of(m_breakpoints.begin(), m_breakpoints.end(),
-                     [address](const auto& bp) { return bp.address == address && bp.log_on_hit; });
+  if (bp == m_breakpoints.end() || !EvaluateCondition(bp->condition))
+    return nullptr;
+
+  return &*bp;
 }
 
 BreakPoints::TBreakPointsStr BreakPoints::GetStrings() const
@@ -57,10 +57,16 @@ BreakPoints::TBreakPointsStr BreakPoints::GetStrings() const
     {
       std::ostringstream ss;
       ss.imbue(std::locale::classic());
-
-      ss << std::hex << bp.address << " " << (bp.is_enabled ? "n" : "")
-         << (bp.log_on_hit ? "l" : "") << (bp.break_on_hit ? "b" : "");
-      bp_strings.push_back(ss.str());
+      ss << fmt::format("${:08x} ", bp.address);
+      if (bp.is_enabled)
+        ss << "n";
+      if (bp.log_on_hit)
+        ss << "l";
+      if (bp.break_on_hit)
+        ss << "b";
+      if (bp.condition)
+        ss << "c " << bp.condition->GetText();
+      bp_strings.emplace_back(ss.str());
     }
   }
 
@@ -76,32 +82,43 @@ void BreakPoints::AddFromStrings(const TBreakPointsStr& bp_strings)
     std::istringstream iss(bp_string);
     iss.imbue(std::locale::classic());
 
+    if (iss.peek() == '$')
+      iss.ignore();
+
     iss >> std::hex >> bp.address;
     iss >> flags;
     bp.is_enabled = flags.find('n') != flags.npos;
     bp.log_on_hit = flags.find('l') != flags.npos;
     bp.break_on_hit = flags.find('b') != flags.npos;
+    if (flags.find('c') != std::string::npos)
+    {
+      iss >> std::ws;
+      std::string condition;
+      std::getline(iss, condition);
+      bp.condition = Expression::TryParse(condition);
+    }
     bp.is_temporary = false;
-    Add(bp);
+    Add(std::move(bp));
   }
 }
 
-void BreakPoints::Add(const TBreakPoint& bp)
+void BreakPoints::Add(TBreakPoint bp)
 {
   if (IsAddressBreakPoint(bp.address))
     return;
 
-  m_breakpoints.push_back(bp);
-
   JitInterface::InvalidateICache(bp.address, 4, true);
+
+  m_breakpoints.emplace_back(std::move(bp));
 }
 
 void BreakPoints::Add(u32 address, bool temp)
 {
-  BreakPoints::Add(address, temp, true, false);
+  BreakPoints::Add(address, temp, true, false, std::nullopt);
 }
 
-void BreakPoints::Add(u32 address, bool temp, bool break_on_hit, bool log_on_hit)
+void BreakPoints::Add(u32 address, bool temp, bool break_on_hit, bool log_on_hit,
+                      std::optional<Expression> condition)
 {
   // Only add new addresses
   if (IsAddressBreakPoint(address))
@@ -113,8 +130,9 @@ void BreakPoints::Add(u32 address, bool temp, bool break_on_hit, bool log_on_hit
   bp.break_on_hit = break_on_hit;
   bp.log_on_hit = log_on_hit;
   bp.address = address;
+  bp.condition = std::move(condition);
 
-  m_breakpoints.push_back(bp);
+  m_breakpoints.emplace_back(std::move(bp));
 
   JitInterface::InvalidateICache(address, 4, true);
 }

Source/Core/Core/PowerPC/BreakPoints.h

@@ -4,10 +4,12 @@
 #pragma once
 
 #include <cstddef>
+#include <optional>
 #include <string>
 #include <vector>
 
 #include "Common/CommonTypes.h"
+#include "Core/PowerPC/Expression.h"
 
 namespace Common
 {
@@ -21,6 +23,7 @@ struct TBreakPoint
   bool is_temporary = false;
   bool log_on_hit = false;
   bool break_on_hit = false;
+  std::optional<Expression> condition;
 };
 
 struct TMemCheck
@@ -59,13 +62,13 @@ public:
   bool IsAddressBreakPoint(u32 address) const;
   bool IsBreakPointEnable(u32 adresss) const;
   bool IsTempBreakPoint(u32 address) const;
-  bool IsBreakPointBreakOnHit(u32 address) const;
-  bool IsBreakPointLogOnHit(u32 address) const;
+  const TBreakPoint* GetBreakpoint(u32 address) const;
 
   // Add BreakPoint
-  void Add(u32 address, bool temp, bool break_on_hit, bool log_on_hit);
+  void Add(u32 address, bool temp, bool break_on_hit, bool log_on_hit,
+           std::optional<Expression> condition);
   void Add(u32 address, bool temp = false);
-  void Add(const TBreakPoint& bp);
+  void Add(TBreakPoint bp);
 
   // Modify Breakpoint
   bool ToggleBreakPoint(u32 address);

Source/Core/Core/PowerPC/Expression.cpp

@@ -0,0 +1,269 @@
+// Copyright 2020 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "Core/PowerPC/Expression.h"
+
+#include <algorithm>
+#include <cstdlib>
+#include <fmt/format.h>
+#include <optional>
+#include <string>
+#include <string_view>
+#include <utility>
+
+#include <expr.h>
+
+#include "Common/BitUtils.h"
+#include "Common/CommonTypes.h"
+#include "Common/Logging/Log.h"
+#include "Core/Core.h"
+#include "Core/PowerPC/MMU.h"
+#include "Core/PowerPC/PowerPC.h"
+
+template <typename T>
+static T HostRead(u32 address);
+
+template <typename T>
+static void HostWrite(T var, u32 address);
+
+template <>
+u8 HostRead(u32 address)
+{
+  return PowerPC::HostRead_U8(address);
+}
+
+template <>
+u16 HostRead(u32 address)
+{
+  return PowerPC::HostRead_U16(address);
+}
+
+template <>
+u32 HostRead(u32 address)
+{
+  return PowerPC::HostRead_U32(address);
+}
+
+template <>
+u64 HostRead(u32 address)
+{
+  return PowerPC::HostRead_U64(address);
+}
+
+template <>
+void HostWrite(u8 var, u32 address)
+{
+  PowerPC::HostWrite_U8(var, address);
+}
+
+template <>
+void HostWrite(u16 var, u32 address)
+{
+  PowerPC::HostWrite_U16(var, address);
+}
+
+template <>
+void HostWrite(u32 var, u32 address)
+{
+  PowerPC::HostWrite_U32(var, address);
+}
+
+template <>
+void HostWrite(u64 var, u32 address)
+{
+  PowerPC::HostWrite_U64(var, address);
+}
+
+template <typename T, typename U = T>
+static double HostReadFunc(expr_func* f, vec_expr_t* args, void* c)
+{
+  if (vec_len(args) != 1)
+    return 0;
+  const u32 address = static_cast<u32>(expr_eval(&vec_nth(args, 0)));
+  return Common::BitCast<T>(HostRead<U>(address));
+}
+
+template <typename T, typename U = T>
+static double HostWriteFunc(expr_func* f, vec_expr_t* args, void* c)
+{
+  if (vec_len(args) != 2)
+    return 0;
+  const T var = static_cast<T>(expr_eval(&vec_nth(args, 0)));
+  const u32 address = static_cast<u32>(expr_eval(&vec_nth(args, 1)));
+  HostWrite<U>(Common::BitCast<U>(var), address);
+  return var;
+}
+
+template <typename T, typename U = T>
+static double CastFunc(expr_func* f, vec_expr_t* args, void* c)
+{
+  if (vec_len(args) != 1)
+    return 0;
+  return Common::BitCast<T>(static_cast<U>(expr_eval(&vec_nth(args, 0))));
+}
+
+static std::array<expr_func, 21> g_expr_funcs{{
+    // For internal storage and comparisons, everything is auto-converted to Double.
+    // If u64 ints are added, this could produce incorrect results.
+    {"read_u8", HostReadFunc<u8>},
+    {"read_s8", HostReadFunc<s8, u8>},
+    {"read_u16", HostReadFunc<u16>},
+    {"read_s16", HostReadFunc<s16, u16>},
+    {"read_u32", HostReadFunc<u32>},
+    {"read_s32", HostReadFunc<s32, u32>},
+    {"read_f32", HostReadFunc<float, u32>},
+    {"read_f64", HostReadFunc<double, u64>},
+    {"write_u8", HostWriteFunc<u8>},
+    {"write_u16", HostWriteFunc<u16>},
+    {"write_u32", HostWriteFunc<u32>},
+    {"write_f32", HostWriteFunc<float, u32>},
+    {"write_f64", HostWriteFunc<double, u64>},
+    {"u8", CastFunc<u8>},
+    {"s8", CastFunc<s8, u8>},
+    {"u16", CastFunc<u16>},
+    {"s16", CastFunc<s16, u16>},
+    {"u32", CastFunc<u32>},
+    {"s32", CastFunc<s32, u32>},
+    {},
+}};
+
+void ExprDeleter::operator()(expr* expression) const
+{
+  expr_destroy(expression, nullptr);
+}
+
+void ExprVarListDeleter::operator()(expr_var_list* vars) const
+{
+  // Free list elements
+  expr_destroy(nullptr, vars);
+  // Free list object
+  delete vars;
+}
+
+Expression::Expression(std::string_view text, ExprPointer ex, ExprVarListPointer vars)
+    : m_text(text), m_expr(std::move(ex)), m_vars(std::move(vars))
+{
+  for (auto* v = m_vars->head; v != nullptr; v = v->next)
+  {
+    const std::string_view name = v->name;
+    VarBinding bind;
+
+    if (name.length() >= 2 && name.length() <= 3)
+    {
+      if (name[0] == 'r' || name[0] == 'f')
+      {
+        char* end = nullptr;
+        const int index = std::strtol(name.data() + 1, &end, 10);
+        if (index >= 0 && index <= 31 && end == name.data() + name.length())
+        {
+          bind.type = name[0] == 'r' ? VarBindingType::GPR : VarBindingType::FPR;
+          bind.index = index;
+        }
+      }
+      else if (name == "lr")
+      {
+        bind.type = VarBindingType::SPR;
+        bind.index = SPR_LR;
+      }
+      else if (name == "ctr")
+      {
+        bind.type = VarBindingType::SPR;
+        bind.index = SPR_CTR;
+      }
+      else if (name == "pc")
+      {
+        bind.type = VarBindingType::PCtr;
+      }
+    }
+
+    m_binds.emplace_back(bind);
+  }
+}
+
+std::optional<Expression> Expression::TryParse(std::string_view text)
+{
+  ExprVarListPointer vars{new expr_var_list{}};
+  ExprPointer ex{expr_create(text.data(), text.length(), vars.get(), g_expr_funcs.data())};
+  if (!ex)
+    return std::nullopt;
+
+  return Expression{text, std::move(ex), std::move(vars)};
+}
+
+double Expression::Evaluate() const
+{
+  SynchronizeBindings(SynchronizeDirection::From);
+
+  double result = expr_eval(m_expr.get());
+
+  SynchronizeBindings(SynchronizeDirection::To);
+
+  Reporting(result);
+
+  return result;
+}
+
+void Expression::SynchronizeBindings(SynchronizeDirection dir) const
+{
+  auto bind = m_binds.begin();
+  for (auto* v = m_vars->head; v != nullptr; v = v->next, ++bind)
+  {
+    switch (bind->type)
+    {
+    case VarBindingType::Zero:
+      if (dir == SynchronizeDirection::From)
+        v->value = 0;
+      break;
+    case VarBindingType::GPR:
+      if (dir == SynchronizeDirection::From)
+        v->value = static_cast<double>(GPR(bind->index));
+      else
+        GPR(bind->index) = static_cast<u32>(static_cast<s64>(v->value));
+      break;
+    case VarBindingType::FPR:
+      if (dir == SynchronizeDirection::From)
+        v->value = rPS(bind->index).PS0AsDouble();
+      else
+        rPS(bind->index).SetPS0(v->value);
+      break;
+    case VarBindingType::SPR:
+      if (dir == SynchronizeDirection::From)
+        v->value = static_cast<double>(rSPR(bind->index));
+      else
+        rSPR(bind->index) = static_cast<u32>(static_cast<s64>(v->value));
+      break;
+    case VarBindingType::PCtr:
+      if (dir == SynchronizeDirection::From)
+        v->value = static_cast<double>(PC);
+      break;
+    }
+  }
+}
+
+void Expression::Reporting(const double result) const
+{
+  bool is_nan = std::isnan(result);
+  std::string message;
+
+  for (auto* v = m_vars->head; v != nullptr; v = v->next)
+  {
+    if (std::isnan(v->value))
+      is_nan = true;
+
+    fmt::format_to(std::back_inserter(message), "  {}={}", v->name, v->value);
+  }
+
+  if (is_nan)
+  {
+    message.append("\nBreakpoint condition encountered a NaN");
+    Core::DisplayMessage("Breakpoint condition has encountered a NaN.", 2000);
+  }
+
+  if (result != 0.0 || is_nan)
+    NOTICE_LOG_FMT(MEMMAP, "Breakpoint condition returned: {}. Vars:{}", result, message);
+}
+
+std::string Expression::GetText() const
+{
+  return m_text;
+}

Source/Core/Core/PowerPC/Expression.h

@@ -0,0 +1,74 @@
+// Copyright 2020 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <memory>
+#include <optional>
+#include <string>
+#include <string_view>
+#include <vector>
+
+struct expr;
+struct expr_var_list;
+
+struct ExprDeleter
+{
+  void operator()(expr* expression) const;
+};
+
+using ExprPointer = std::unique_ptr<expr, ExprDeleter>;
+
+struct ExprVarListDeleter
+{
+  void operator()(expr_var_list* vars) const;
+};
+
+using ExprVarListPointer = std::unique_ptr<expr_var_list, ExprVarListDeleter>;
+
+class Expression
+{
+public:
+  static std::optional<Expression> TryParse(std::string_view text);
+
+  double Evaluate() const;
+
+  std::string GetText() const;
+
+private:
+  enum class SynchronizeDirection
+  {
+    From,
+    To,
+  };
+
+  enum class VarBindingType
+  {
+    Zero,
+    GPR,
+    FPR,
+    SPR,
+    PCtr,
+  };
+
+  struct VarBinding
+  {
+    VarBindingType type = VarBindingType::Zero;
+    int index = -1;
+  };
+
+  Expression(std::string_view text, ExprPointer ex, ExprVarListPointer vars);
+
+  void SynchronizeBindings(SynchronizeDirection dir) const;
+  void Reporting(const double result) const;
+
+  std::string m_text;
+  ExprPointer m_expr;
+  ExprVarListPointer m_vars;
+  std::vector<VarBinding> m_binds;
+};
+
+inline bool EvaluateCondition(const std::optional<Expression>& condition)
+{
+  return !condition || condition->Evaluate() != 0.0;
+}

Source/Core/Core/PowerPC/PowerPC.cpp

@@ -610,16 +610,18 @@ void CheckExternalExceptions()
 
 void CheckBreakPoints()
 {
-  if (!PowerPC::breakpoints.IsBreakPointEnable(PC))
+  const TBreakPoint* bp = PowerPC::breakpoints.GetBreakpoint(PC);
+
+  if (bp == nullptr)
     return;
 
-  if (PowerPC::breakpoints.IsBreakPointBreakOnHit(PC))
+  if (bp->break_on_hit)
   {
     CPU::Break();
     if (GDBStub::IsActive())
       GDBStub::TakeControl();
   }
-  if (PowerPC::breakpoints.IsBreakPointLogOnHit(PC))
+  if (bp->log_on_hit)
   {
     NOTICE_LOG_FMT(MEMMAP,
                    "BP {:08x} {}({:08x} {:08x} {:08x} {:08x} {:08x} {:08x} {:08x} {:08x} {:08x} "

Source/Core/DolphinLib.props

@@ -405,6 +405,7 @@
     <ClInclude Include="Core\PowerPC\CachedInterpreter\InterpreterBlockCache.h" />
     <ClInclude Include="Core\PowerPC\ConditionRegister.h" />
     <ClInclude Include="Core\PowerPC\CPUCoreBase.h" />
+    <ClInclude Include="Core\PowerPC\Expression.h" />
     <ClInclude Include="Core\PowerPC\GDBStub.h" />
     <ClInclude Include="Core\PowerPC\Gekko.h" />
     <ClInclude Include="Core\PowerPC\Interpreter\ExceptionUtils.h" />
@@ -1029,6 +1030,7 @@
     <ClCompile Include="Core\PowerPC\CachedInterpreter\CachedInterpreter.cpp" />
     <ClCompile Include="Core\PowerPC\CachedInterpreter\InterpreterBlockCache.cpp" />
     <ClCompile Include="Core\PowerPC\ConditionRegister.cpp" />
+    <ClCompile Include="Core\PowerPC\Expression.cpp" />
     <ClCompile Include="Core\PowerPC\GDBStub.cpp" />
     <ClCompile Include="Core\PowerPC\Interpreter\Interpreter_Branch.cpp" />
     <ClCompile Include="Core\PowerPC\Interpreter\Interpreter_FloatingPoint.cpp" />

Source/Core/DolphinQt/Debugger/BreakpointWidget.cpp

@@ -15,6 +15,7 @@
 #include "Core/ConfigManager.h"
 #include "Core/Core.h"
 #include "Core/PowerPC/BreakPoints.h"
+#include "Core/PowerPC/Expression.h"
 #include "Core/PowerPC/PPCSymbolDB.h"
 #include "Core/PowerPC/PowerPC.h"
 
@@ -86,7 +87,7 @@ void BreakpointWidget::CreateWidgets()
   m_table = new QTableWidget;
   m_table->setTabKeyNavigation(false);
   m_table->setContentsMargins(0, 0, 0, 0);
-  m_table->setColumnCount(5);
+  m_table->setColumnCount(6);
   m_table->setSelectionMode(QAbstractItemView::SingleSelection);
   m_table->setSelectionBehavior(QAbstractItemView::SelectRows);
   m_table->setEditTriggers(QAbstractItemView::NoEditTriggers);
@@ -160,7 +161,7 @@ void BreakpointWidget::Update()
   m_table->clear();
 
   m_table->setHorizontalHeaderLabels(
-      {tr("Active"), tr("Type"), tr("Function"), tr("Address"), tr("Flags")});
+      {tr("Active"), tr("Type"), tr("Function"), tr("Address"), tr("Flags"), tr("Condition")});
 
   int i = 0;
   m_table->setRowCount(i);
@@ -203,6 +204,13 @@ void BreakpointWidget::Update()
 
     m_table->setItem(i, 4, create_item(flags));
 
+    QString condition;
+
+    if (bp.condition)
+      condition = QString::fromStdString(bp.condition->GetText());
+
+    m_table->setItem(i, 5, create_item(condition));
+
     i++;
   }
 
@@ -387,12 +395,15 @@ void BreakpointWidget::OnContextMenu()
 
 void BreakpointWidget::AddBP(u32 addr)
 {
-  AddBP(addr, false, true, true);
+  AddBP(addr, false, true, true, {});
 }
 
-void BreakpointWidget::AddBP(u32 addr, bool temp, bool break_on_hit, bool log_on_hit)
+void BreakpointWidget::AddBP(u32 addr, bool temp, bool break_on_hit, bool log_on_hit,
+                             const QString& condition)
 {
-  PowerPC::breakpoints.Add(addr, temp, break_on_hit, log_on_hit);
+  PowerPC::breakpoints.Add(
+      addr, temp, break_on_hit, log_on_hit,
+      !condition.isEmpty() ? Expression::TryParse(condition.toUtf8().constData()) : std::nullopt);
 
   emit BreakpointsChanged();
   Update();

Source/Core/DolphinQt/Debugger/BreakpointWidget.h

@@ -21,7 +21,7 @@ public:
   ~BreakpointWidget();
 
   void AddBP(u32 addr);
-  void AddBP(u32 addr, bool temp, bool break_on_hit, bool log_on_hit);
+  void AddBP(u32 addr, bool temp, bool break_on_hit, bool log_on_hit, const QString& condition);
   void AddAddressMBP(u32 addr, bool on_read = true, bool on_write = true, bool do_log = true,
                      bool do_break = true);
   void AddRangedMBP(u32 from, u32 to, bool do_read = true, bool do_write = true, bool do_log = true,

Source/Core/DolphinQt/Debugger/NewBreakpointDialog.cpp

@@ -11,9 +11,11 @@
 #include <QHBoxLayout>
 #include <QLabel>
 #include <QLineEdit>
+#include <QPushButton>
 #include <QRadioButton>
 #include <QVBoxLayout>
 
+#include "Core/PowerPC/Expression.h"
 #include "DolphinQt/Debugger/BreakpointWidget.h"
 #include "DolphinQt/QtUtils/ModalMessageBox.h"
 
@@ -35,16 +37,25 @@ void NewBreakpointDialog::CreateWidgets()
   auto* type_group = new QButtonGroup(this);
 
   // Instruction BP
+  auto* top_layout = new QHBoxLayout;
   m_instruction_bp = new QRadioButton(tr("Instruction Breakpoint"));
   m_instruction_bp->setChecked(true);
   type_group->addButton(m_instruction_bp);
   m_instruction_box = new QGroupBox;
   m_instruction_address = new QLineEdit;
+  m_instruction_condition = new QLineEdit;
+  m_cond_help_btn = new QPushButton(tr("Help"));
 
-  auto* instruction_layout = new QHBoxLayout;
+  top_layout->addWidget(m_instruction_bp);
+  top_layout->addStretch();
+  top_layout->addWidget(m_cond_help_btn);
+
+  auto* instruction_layout = new QGridLayout;
   m_instruction_box->setLayout(instruction_layout);
-  instruction_layout->addWidget(new QLabel(tr("Address:")));
-  instruction_layout->addWidget(m_instruction_address);
+  instruction_layout->addWidget(new QLabel(tr("Address:")), 0, 0);
+  instruction_layout->addWidget(m_instruction_address, 0, 1);
+  instruction_layout->addWidget(new QLabel(tr("Condition:")), 1, 0);
+  instruction_layout->addWidget(m_instruction_condition, 1, 1);
 
   // Memory BP
   m_memory_bp = new QRadioButton(tr("Memory Breakpoint"));
@@ -102,7 +113,7 @@ void NewBreakpointDialog::CreateWidgets()
 
   auto* layout = new QVBoxLayout;
 
-  layout->addWidget(m_instruction_bp);
+  layout->addLayout(top_layout);
   layout->addWidget(m_instruction_box);
   layout->addWidget(m_memory_bp);
   layout->addWidget(m_memory_box);
@@ -119,6 +130,8 @@ void NewBreakpointDialog::ConnectWidgets()
   connect(m_buttons, &QDialogButtonBox::accepted, this, &NewBreakpointDialog::accept);
   connect(m_buttons, &QDialogButtonBox::rejected, this, &NewBreakpointDialog::reject);
 
+  connect(m_cond_help_btn, &QPushButton::clicked, this, &NewBreakpointDialog::ShowConditionHelp);
+
   connect(m_instruction_bp, &QRadioButton::toggled, this, &NewBreakpointDialog::OnBPTypeChanged);
   connect(m_memory_bp, &QRadioButton::toggled, this, &NewBreakpointDialog::OnBPTypeChanged);
 
@@ -174,7 +187,15 @@ void NewBreakpointDialog::accept()
       return;
     }
 
-    m_parent->AddBP(address, false, do_break, do_log);
+    const QString condition = m_instruction_condition->text().trimmed();
+
+    if (!condition.isEmpty() && !Expression::TryParse(condition.toUtf8().constData()))
+    {
+      invalid_input(tr("Condition"));
+      return;
+    }
+
+    m_parent->AddBP(address, false, do_break, do_log, condition);
   }
   else
   {
@@ -205,3 +226,46 @@ void NewBreakpointDialog::accept()
 
   QDialog::accept();
 }
+
+void NewBreakpointDialog::ShowConditionHelp()
+{
+  const auto message = QStringLiteral(
+      "Set a code breakpoint for when an instruction is executed. Use with the code widget.\n"
+      "\n"
+      "Conditions:\n"
+      "Sets an expression that is evaluated when a breakpoint is hit. If the expression is false "
+      "or 0, the breakpoint is ignored until hit again. Statements should be separated by a comma. "
+      "Only the last statement will be used to determine what to do.\n"
+      "\n"
+      "Registers that can be referenced:\n"
+      "GPRs : r0..r31\n"
+      "FPRs : f0..f31\n LR, CTR, PC\n"
+      "\n"
+      "Functions:\n"
+      "Set a register: r1 = 8\n"
+      "Casts: s8(0xff). Available: s8, u8, s16, u16, s32, u32\n"
+      "Read Memory: read_u32(0x80000000). Available: u8, s8, u16, s16, u32, s32, f32, f64\n"
+      "Write Memory: write_u32(r3, 0x80000000). Available: u8, u16, u32, f32, f64\n"
+      "*currently writing will always be triggered\n"
+      "\n"
+      "Operations:\n"
+      "Unary: -u, !u, ~u\n"
+      "Math: *  / + -, power: **, remainder: %, shift: <<, >>\n"
+      "Compare: <, <=, >, >=, ==, !=, &&, ||\n"
+      "Bitwise: &, |, ^\n"
+      "\n"
+      "Examples:\n"
+      "r4 == 1\n"
+      "f0 == 1.0 && f2 < 10.0\n"
+      "r26 <= r0 && ((r5 + 3) & -4) * ((r6 + 3) & -4)* 4 > r0\n"
+      "p = r3 + 0x8, p == 0x8003510 && read_u32(p) != 0\n"
+      "Write and break: r4 = 8, 1\n"
+      "Write and continue: f3 = f1 + f2, 0\n"
+      "The condition must always be last\n\n"
+      "All variables will be printed in the Memory Interface log, if there's a hit or a NaN "
+      "result. To check for issues, assign a variable to your equation, so it can be printed.\n\n"
+      "Note: All values are internally converted to Doubles for calculations. It's possible for "
+      "them to go out of range or to become NaN. A warning will be given if NaN is returned, and "
+      "the var that became NaN will be logged.");
+  ModalMessageBox::information(this, tr("Conditional help"), message);
+}

Source/Core/DolphinQt/Debugger/NewBreakpointDialog.h

@@ -29,11 +29,14 @@ private:
 
   void OnBPTypeChanged();
   void OnAddressTypeChanged();
+  void ShowConditionHelp();
 
   // Instruction BPs
   QRadioButton* m_instruction_bp;
   QGroupBox* m_instruction_box;
   QLineEdit* m_instruction_address;
+  QLineEdit* m_instruction_condition;
+  QPushButton* m_cond_help_btn;
 
   // Memory BPs
   QRadioButton* m_memory_bp;