[Lldb-commits] [PATCH] D15175: Fix breakpoint language filtering for other C variants (like C99) and Pascal.

[Dawn Perchik via lldb-commits]

dawn created this revision.
dawn added a reviewer: jingham.
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This patch fixes setting breakpoints on symbol for variants of C and Pascal where the language is "unknown" within the filtering process added in r252356.  It also renames GetLanguageForSymbolByName to GuessLanguageForSymbolByName and adds comments explaining the pitfalls of the flawed assumption that the language can be determined solely from the name and target.

Comment: Our users want to be able to set breakpoints in C, C++ or Pascal, but since the parsing of Pascal breakpoint identifiers is incompatible with ObjC, they're forced to set the target language option to Pascal.  After r252356 however, the Pascal identifiers are interpreted as C++ and the C symbols are unknown, so all symbols are filtered out because they don't match the target language setting of Pascal, and they can no longer set symbolic breakpoints.  I don't see a way to fix this without breaking the intent of r252356.  Locally we have had to disable the filtering code.  Ideas for how to resolve this?

Repository:
  rL LLVM

http://reviews.llvm.org/D15175

Files:
  include/lldb/Target/LanguageRuntime.h
  source/Breakpoint/BreakpointResolverName.cpp
  source/Target/LanguageRuntime.cpp

Index: source/Target/LanguageRuntime.cpp
===================================================================
--- source/Target/LanguageRuntime.cpp
+++ source/Target/LanguageRuntime.cpp
@@ -347,16 +347,21 @@
 }
 
 lldb::LanguageType
-LanguageRuntime::GetLanguageForSymbolByName (Target &target, const char *symbol_name)
+LanguageRuntime::GuessLanguageForSymbolByName (Target &target, const char *symbol_name)
 {
-    // This is not the right way to do this.  Different targets could have different ways of mangling names
-    // from a given language.  So we should ask the various LanguageRuntime plugin instances for this target
-    // to recognize the name.  But right now the plugin instances depend on the process, not the target.
-    // That is unfortunate, because I want to use this for filtering breakpoints by language, and so I need to know
-    // the "language for symbol-name" prior to running.  So we'd have to make a "LanguageRuntimeTarget" and
-    // "LanguageRuntimeProcess", and direct the questions that don't need a running process to the former, and that
-    // do to the latter.
+    // We "guess" the language because we can't determine a symbol's language from it's name.
+    // For example, a Pascal symbol can be mangled using the C++ Itanium scheme, and defined
+    // in a compilation unit within the same module as other C++ units.
     //
+    // In addition, different targets could have different ways of mangling names from a given
+    // language, likewise compilation units within those targets.  It would help to be able to
+    // ask the various LanguageRuntime plugin instances for this target to recognize the name,
+    // but right now the plugin instances depend on the process, not the target.  That is
+    // unfortunate, because to use this for filtering breakpoints by language, we need to know
+    // the "language for symbol-name" prior to running.  So we'd have to make a
+    // "LanguageRuntimeTarget" and "LanguageRuntimeProcess", and direct the questions that don't
+    // need a running process to the former, and that do to the latter.
+    //
     // That's more work than I want to do for this feature.
     if (CPlusPlusLanguage::IsCPPMangledName (symbol_name))
         return eLanguageTypeC_plus_plus;
Index: source/Breakpoint/BreakpointResolverName.cpp
===================================================================
--- source/Breakpoint/BreakpointResolverName.cpp
+++ source/Breakpoint/BreakpointResolverName.cpp
@@ -279,8 +279,9 @@
                 const char *name = sc.GetFunctionName(Mangled::ePreferMangled).AsCString();
                 if (name)
                 {
-                    LanguageType sym_language = LanguageRuntime::GetLanguageForSymbolByName(target, name);
-                    if (m_language == eLanguageTypeC)
+                    LanguageType sym_language = LanguageRuntime::GuessLanguageForSymbolByName(target, name);
+                    if (Language::LanguageIsC(m_language) ||
+                        Language::LanguageIsPascal(m_language))
                     {
                         // We don't currently have a way to say "This symbol name is C" so for now, C means
                         // not ObjC and not C++, etc...
@@ -293,6 +294,12 @@
                     }
                     else if (sym_language != m_language)
                     {
+                        // Note: This code prevents us from being able to find symbols
+                        // like 'printf' if the target language's option is set.  It
+                        // would be better to limit this filtering to only when the
+                        // breakpoint's language option is set (and not the target's),
+                        // but we can't know if m_language was set from the target or
+                        // breakpoint option.
                         remove_it = true;
                     }
                 }
Index: include/lldb/Target/LanguageRuntime.h
===================================================================
--- include/lldb/Target/LanguageRuntime.h
+++ include/lldb/Target/LanguageRuntime.h
@@ -118,7 +118,7 @@
     }
     
     static lldb::LanguageType
-    GetLanguageForSymbolByName (Target &target, const char *symbol_name);
+    GuessLanguageForSymbolByName (Target &target, const char *symbol_name);
     
     Target&
     GetTargetRef()


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