[lldb] Support specifying a language for breakpoint conditions (#147603)

LLDB breakpoint conditions take an expression that's evaluated using the
language of the code where the breakpoint is located. Users have asked
to have an option to tell it to evaluate the expression in a specific
language.

This is feature is especially helpful for Swift, for example for a
condition based on the value in memory at an offset from a register.
Such a condition is pretty difficult to write in Swift, but easy in C.

This PR adds a new argument (-Y) to specify the language of the
condition expression. We can't reuse the current -L option, since you
might want to break on only Swift symbols, but run a C expression there
as per the example above.

rdar://146119507

Author: JDevlieghere

lldb/include/lldb/Breakpoint/Breakpoint.h

@@ -397,16 +397,12 @@ class Breakpoint : public std::enable_shared_from_this<Breakpoint>,
   /// Set the breakpoint's condition.
   ///
   /// \param[in] condition
-  ///    The condition expression to evaluate when the breakpoint is hit.
-  ///    Pass in nullptr to clear the condition.
-  void SetCondition(const char *condition);
+  ///    The condition to evaluate when the breakpoint is hit.
+  ///    Pass in an empty condition to clear the condition.
+  void SetCondition(StopCondition condition);
 
-  /// Return a pointer to the text of the condition expression.
-  ///
-  /// \return
-  ///    A pointer to the condition expression text, or nullptr if no
-  //     condition has been set.
-  const char *GetConditionText() const;
+  /// Return the breakpoint condition.
+  const StopCondition &GetCondition() const;
 
   // The next section are various utility functions.
 

lldb/include/lldb/Breakpoint/BreakpointLocation.h

@@ -128,15 +128,11 @@ class BreakpointLocation
   /// Set the breakpoint location's condition.
   ///
   /// \param[in] condition
-  ///    The condition expression to evaluate when the breakpoint is hit.
-  void SetCondition(const char *condition);
+  ///    The condition to evaluate when the breakpoint is hit.
+  void SetCondition(StopCondition condition);
 
-  /// Return a pointer to the text of the condition expression.
-  ///
-  /// \return
-  ///    A pointer to the condition expression text, or nullptr if no
-  //     condition has been set.
-  const char *GetConditionText(size_t *hash = nullptr) const;
+  /// Return the breakpoint condition.
+  const StopCondition &GetCondition() const;
 
   bool ConditionSaysStop(ExecutionContext &exe_ctx, Status &error);
 

lldb/include/lldb/Breakpoint/BreakpointOptions.h

@@ -12,6 +12,7 @@
 #include <memory>
 #include <string>
 
+#include "lldb/Breakpoint/StopCondition.h"
 #include "lldb/Utility/Baton.h"
 #include "lldb/Utility/Flags.h"
 #include "lldb/Utility/StringList.h"
@@ -245,18 +246,15 @@ friend class Breakpoint;
   const Baton *GetBaton() const;
 
   // Condition
-  /// Set the breakpoint option's condition.
+  /// Set the breakpoint stop condition.
   ///
   /// \param[in] condition
-  ///    The condition expression to evaluate when the breakpoint is hit.
-  void SetCondition(const char *condition);
+  ///    The condition to evaluate when the breakpoint is hit.
+  void SetCondition(StopCondition condition);
 
-  /// Return a pointer to the text of the condition expression.
-  ///
-  /// \return
-  ///    A pointer to the condition expression text, or nullptr if no
-  //     condition has been set.
-  const char *GetConditionText(size_t *hash = nullptr) const;
+  /// Return the breakpoint condition.
+  const StopCondition &GetCondition() const;
+  StopCondition &GetCondition();
 
   // Enabled/Ignore Count
 
@@ -390,9 +388,7 @@ friend class Breakpoint;
   /// Thread for which this breakpoint will stop.
   std::unique_ptr<ThreadSpec> m_thread_spec_up;
   /// The condition to test.
-  std::string m_condition_text;
-  /// Its hash, so that locations know when the condition is updated.
-  size_t m_condition_text_hash;
+  StopCondition m_condition;
   /// If set, inject breakpoint condition into process.
   bool m_inject_condition;
   /// If set, auto-continue from breakpoint.

lldb/include/lldb/Breakpoint/StopCondition.h

@@ -0,0 +1,55 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLDB_BREAKPOINT_STOPCONDITION_H
+#define LLDB_BREAKPOINT_STOPCONDITION_H
+
+#include "lldb/lldb-private.h"
+#include "llvm/ADT/StringRef.h"
+
+namespace lldb_private {
+
+class StopCondition {
+public:
+  StopCondition() = default;
+  StopCondition(std::string text,
+                lldb::LanguageType language = lldb::eLanguageTypeUnknown)
+      : m_language(language) {
+    SetText(std::move(text));
+  }
+
+  explicit operator bool() const { return !m_text.empty(); }
+
+  llvm::StringRef GetText() const { return m_text; }
+
+  void SetText(std::string text) {
+    static std::hash<std::string> hasher;
+    m_text = std::move(text);
+    m_hash = hasher(text);
+  }
+
+  size_t GetHash() const { return m_hash; }
+
+  lldb::LanguageType GetLanguage() const { return m_language; }
+
+  void SetLanguage(lldb::LanguageType language) { m_language = language; }
+
+private:
+  /// The condition to test.
+  std::string m_text;
+
+  /// Its hash, so that locations know when the condition is updated.
+  size_t m_hash = 0;
+
+  /// The language for this condition.
+  lldb::LanguageType m_language = lldb::eLanguageTypeUnknown;
+};
+
+} // namespace lldb_private
+
+#endif // LLDB_BREAKPOINT_STOPCONDITION_H

lldb/source/API/SBBreakpoint.cpp

@@ -275,7 +275,7 @@ void SBBreakpoint::SetCondition(const char *condition) {
   if (bkpt_sp) {
     std::lock_guard<std::recursive_mutex> guard(
         bkpt_sp->GetTarget().GetAPIMutex());
-    bkpt_sp->SetCondition(condition);
+    bkpt_sp->SetCondition(StopCondition(condition));
   }
 }
 
@@ -288,7 +288,7 @@ const char *SBBreakpoint::GetCondition() {
 
   std::lock_guard<std::recursive_mutex> guard(
       bkpt_sp->GetTarget().GetAPIMutex());
-  return ConstString(bkpt_sp->GetConditionText()).GetCString();
+  return ConstString(bkpt_sp->GetCondition().GetText()).GetCString();
 }
 
 void SBBreakpoint::SetAutoContinue(bool auto_continue) {

lldb/source/API/SBBreakpointLocation.cpp

@@ -160,7 +160,7 @@ void SBBreakpointLocation::SetCondition(const char *condition) {
   if (loc_sp) {
     std::lock_guard<std::recursive_mutex> guard(
         loc_sp->GetTarget().GetAPIMutex());
-    loc_sp->SetCondition(condition);
+    loc_sp->SetCondition(StopCondition(condition));
   }
 }
 
@@ -173,7 +173,7 @@ const char *SBBreakpointLocation::GetCondition() {
 
   std::lock_guard<std::recursive_mutex> guard(
       loc_sp->GetTarget().GetAPIMutex());
-  return ConstString(loc_sp->GetConditionText()).GetCString();
+  return ConstString(loc_sp->GetCondition().GetText()).GetCString();
 }
 
 void SBBreakpointLocation::SetAutoContinue(bool auto_continue) {

lldb/source/API/SBBreakpointName.cpp

@@ -303,7 +303,7 @@ void SBBreakpointName::SetCondition(const char *condition) {
   std::lock_guard<std::recursive_mutex> guard(
         m_impl_up->GetTarget()->GetAPIMutex());
 
-  bp_name->GetOptions().SetCondition(condition);
+  bp_name->GetOptions().SetCondition(StopCondition(condition));
   UpdateName(*bp_name);
 }
 
@@ -317,7 +317,8 @@ const char *SBBreakpointName::GetCondition() {
   std::lock_guard<std::recursive_mutex> guard(
       m_impl_up->GetTarget()->GetAPIMutex());
 
-  return ConstString(bp_name->GetOptions().GetConditionText()).GetCString();
+  return ConstString(bp_name->GetOptions().GetCondition().GetText())
+      .GetCString();
 }
 
 void SBBreakpointName::SetAutoContinue(bool auto_continue) {

lldb/source/Breakpoint/Breakpoint.cpp

@@ -440,13 +440,13 @@ const char *Breakpoint::GetQueueName() const {
   return m_options.GetThreadSpecNoCreate()->GetQueueName();
 }
 
-void Breakpoint::SetCondition(const char *condition) {
-  m_options.SetCondition(condition);
+void Breakpoint::SetCondition(StopCondition condition) {
+  m_options.SetCondition(std::move(condition));
   SendBreakpointChangedEvent(eBreakpointEventTypeConditionChanged);
 }
 
-const char *Breakpoint::GetConditionText() const {
-  return m_options.GetConditionText();
+const StopCondition &Breakpoint::GetCondition() const {
+  return m_options.GetCondition();
 }
 
 // This function is used when "baton" doesn't need to be freed

lldb/source/Breakpoint/BreakpointLocation.cpp

@@ -203,14 +203,13 @@ void BreakpointLocation::ClearCallback() {
   GetLocationOptions().ClearCallback();
 }
 
-void BreakpointLocation::SetCondition(const char *condition) {
-  GetLocationOptions().SetCondition(condition);
+void BreakpointLocation::SetCondition(StopCondition condition) {
+  GetLocationOptions().SetCondition(std::move(condition));
   SendBreakpointLocationChangedEvent(eBreakpointEventTypeConditionChanged);
 }
 
-const char *BreakpointLocation::GetConditionText(size_t *hash) const {
-  return GetOptionsSpecifyingKind(BreakpointOptions::eCondition)
-      .GetConditionText(hash);
+const StopCondition &BreakpointLocation::GetCondition() const {
+  return GetOptionsSpecifyingKind(BreakpointOptions::eCondition).GetCondition();
 }
 
 bool BreakpointLocation::ConditionSaysStop(ExecutionContext &exe_ctx,
@@ -219,10 +218,9 @@ bool BreakpointLocation::ConditionSaysStop(ExecutionContext &exe_ctx,
 
   std::lock_guard<std::mutex> guard(m_condition_mutex);
 
-  size_t condition_hash;
-  const char *condition_text = GetConditionText(&condition_hash);
+  StopCondition condition = GetCondition();
 
-  if (!condition_text) {
+  if (!condition) {
     m_user_expression_sp.reset();
     return false;
   }
@@ -231,19 +229,22 @@ bool BreakpointLocation::ConditionSaysStop(ExecutionContext &exe_ctx,
 
   DiagnosticManager diagnostics;
 
-  if (condition_hash != m_condition_hash || !m_user_expression_sp ||
+  if (condition.GetHash() != m_condition_hash || !m_user_expression_sp ||
       !m_user_expression_sp->IsParseCacheable() ||
       !m_user_expression_sp->MatchesContext(exe_ctx)) {
-    LanguageType language = eLanguageTypeUnknown;
-    // See if we can figure out the language from the frame, otherwise use the
-    // default language:
-    CompileUnit *comp_unit = m_address.CalculateSymbolContextCompileUnit();
-    if (comp_unit)
-      language = comp_unit->GetLanguage();
+    LanguageType language = condition.GetLanguage();
+    if (language == lldb::eLanguageTypeUnknown) {
+      // See if we can figure out the language from the frame, otherwise use the
+      // default language:
+      if (CompileUnit *comp_unit =
+              m_address.CalculateSymbolContextCompileUnit())
+        language = comp_unit->GetLanguage();
+    }
 
     m_user_expression_sp.reset(GetTarget().GetUserExpressionForLanguage(
-        condition_text, llvm::StringRef(), language, Expression::eResultTypeAny,
-        EvaluateExpressionOptions(), nullptr, error));
+        condition.GetText(), llvm::StringRef(), language,
+        Expression::eResultTypeAny, EvaluateExpressionOptions(), nullptr,
+        error));
     if (error.Fail()) {
       LLDB_LOGF(log, "Error getting condition expression: %s.",
                 error.AsCString());
@@ -262,7 +263,7 @@ bool BreakpointLocation::ConditionSaysStop(ExecutionContext &exe_ctx,
       return true;
     }
 
-    m_condition_hash = condition_hash;
+    m_condition_hash = condition.GetHash();
   }
 
   // We need to make sure the user sees any parse errors in their condition, so