[Lldb-commits] [lldb] [LLDB] Support exception breakpoints for plugin-provided languages (PR #97675)

[Walter Erquinigo via lldb-commits]

https://github.com/walter-erquinigo updated https://github.com/llvm/llvm-project/pull/97675

>From 5d1a7254d1e1a541a7b901be0d3a84eab42474b2 Mon Sep 17 00:00:00 2001
From: walter erquinigo <walter at modular.com>
Date: Thu, 4 Jul 2024 00:34:14 -0400
Subject: [PATCH 1/2] [LLDB] Support exception breakpoints for plugin-provided
 languages

CommandObjectBreakpoint has a harcoded list of languages for which exception breakpoints can be enabled. I'm making this a bit more generic so that my Mojo plugin can get this feature.
Basically, I'm adding a new overridable method `Language::SupportsExceptionBreakpoints` that can be used by language plugins to determine whether they support this feature or not. This method is used in addition to the hardcoded list and, as an example, I'm using it for the ObjC language support.

Another route is simply to avoid doing the check that it's being done right now and simply try to the create the exception breakpoint for whatever language that is not in the hardcoded list. I'm happy to do that if the reviewers think it's a good idea.

As a note, the other possible place for adding this `SupportsExceptionBreakpoints` method is in `LanguageRuntime`. However, accessing it requires having a process, which is not always the case when invoking the `breakpoint set -E` command. The process might not be alive yet, so `Language` is a good second place for this.

And as a final note, I don't want to make this `SupportsExceptionBreakpoints` complicated. I'm keeping it as simple as possible because it can easily evolve as it's not part of the public API.
---
 lldb/include/lldb/Target/Language.h              | 6 +++++-
 lldb/source/Commands/CommandObjectBreakpoint.cpp | 9 ++++++---
 lldb/source/Plugins/Language/ObjC/ObjCLanguage.h | 2 ++
 3 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/lldb/include/lldb/Target/Language.h b/lldb/include/lldb/Target/Language.h
index ff7c60bf68bfc..9c2c765ce497f 100644
--- a/lldb/include/lldb/Target/Language.h
+++ b/lldb/include/lldb/Target/Language.h
@@ -245,7 +245,7 @@ class Language : public PluginInterface {
   // a match.  But we wouldn't want this to match AnotherA::my_function.  The
   // user is specifying a truncated path, not a truncated set of characters.
   // This function does a language-aware comparison for those purposes.
-  virtual bool DemangledNameContainsPath(llvm::StringRef path, 
+  virtual bool DemangledNameContainsPath(llvm::StringRef path,
                                          ConstString demangled) const;
 
   // if a language has a custom format for printing variable declarations that
@@ -363,6 +363,10 @@ class Language : public PluginInterface {
     return false;
   }
 
+  /// Returns true if this Language supports exception breakpoints via a
+  /// corresponding LanguageRuntime plugin.
+  virtual bool SupportsExceptionBreakpoints() const { return false; }
+
 protected:
   // Classes that inherit from Language can see and modify these
 
diff --git a/lldb/source/Commands/CommandObjectBreakpoint.cpp b/lldb/source/Commands/CommandObjectBreakpoint.cpp
index cd4c7790f447e..a5fe9273fac76 100644
--- a/lldb/source/Commands/CommandObjectBreakpoint.cpp
+++ b/lldb/source/Commands/CommandObjectBreakpoint.cpp
@@ -308,9 +308,6 @@ class CommandObjectBreakpointSet : public CommandObjectParsed {
         case eLanguageTypeC_plus_plus_14:
           m_exception_language = eLanguageTypeC_plus_plus;
           break;
-        case eLanguageTypeObjC:
-          m_exception_language = eLanguageTypeObjC;
-          break;
         case eLanguageTypeObjC_plus_plus:
           error_context =
               "Set exception breakpoints separately for c++ and objective-c";
@@ -319,6 +316,12 @@ class CommandObjectBreakpointSet : public CommandObjectParsed {
           error_context = "Unknown language type for exception breakpoint";
           break;
         default:
+          if (Language *languagePlugin = Language::FindPlugin(language)) {
+            if (languagePlugin->SupportsExceptionBreakpoints()) {
+              m_exception_language = language;
+              break;
+            }
+          }
           error_context = "Unsupported language type for exception breakpoint";
         }
         if (!error_context.empty())
diff --git a/lldb/source/Plugins/Language/ObjC/ObjCLanguage.h b/lldb/source/Plugins/Language/ObjC/ObjCLanguage.h
index a50f4b036108d..a61d0f128370d 100644
--- a/lldb/source/Plugins/Language/ObjC/ObjCLanguage.h
+++ b/lldb/source/Plugins/Language/ObjC/ObjCLanguage.h
@@ -194,6 +194,8 @@ class ObjCLanguage : public Language {
 
   llvm::StringRef GetInstanceVariableName() override { return "self"; }
 
+  bool SupportsExceptionBreakpoints() const override { return true; }
+
   // PluginInterface protocol
   llvm::StringRef GetPluginName() override { return GetPluginNameStatic(); }
 };

>From e99702d0cafaaa87e06a845e3f3e14868f9e800b Mon Sep 17 00:00:00 2001
From: Walter Erquinigo <a20012251 at gmail.com>
Date: Thu, 4 Jul 2024 10:02:45 -0400
Subject: [PATCH 2/2] Update Language.h

---
 lldb/include/lldb/Target/Language.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lldb/include/lldb/Target/Language.h b/lldb/include/lldb/Target/Language.h
index 9c2c765ce497f..2d6e5a40a0c0e 100644
--- a/lldb/include/lldb/Target/Language.h
+++ b/lldb/include/lldb/Target/Language.h
@@ -245,7 +245,7 @@ class Language : public PluginInterface {
   // a match.  But we wouldn't want this to match AnotherA::my_function.  The
   // user is specifying a truncated path, not a truncated set of characters.
   // This function does a language-aware comparison for those purposes.
-  virtual bool DemangledNameContainsPath(llvm::StringRef path,
+  virtual bool DemangledNameContainsPath(llvm::StringRef path, 
                                          ConstString demangled) const;
 
   // if a language has a custom format for printing variable declarations that