From 5c4ce05d6aa0aaac4e7707b55983290093077c8b Mon Sep 17 00:00:00 2001
From: Kuba Brecka <kuba.brecka@gmail.com>
Date: Thu, 5 Mar 2015 09:47:13 +0000
Subject: [PATCH] Symbolizer refactoring: Link symbolizer tools into a fallback
 chain

Reviewed at http://reviews.llvm.org/D8049

llvm-svn: 231361
---
 .../sanitizer_symbolizer_internal.h                |  7 ++++
 .../sanitizer_symbolizer_posix_libcdep.cc          | 41 ++++++++++++++--------
 2 files changed, 34 insertions(+), 14 deletions(-)

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_internal.h b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_internal.h
index a50ee12..5e6a6d5 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_internal.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_internal.h
@@ -28,6 +28,13 @@ const char *ExtractUptr(const char *str, const char *delims, uptr *result);
 
 class SymbolizerTool {
  public:
+  // POSIXSymbolizer implements a "fallback chain" of symbolizer tools. In a
+  // request to symbolize an address, if one tool returns false, the next tool
+  // in the chain will be tried.
+  SymbolizerTool *next;
+
+  SymbolizerTool() : next(nullptr) { }
+
   // Can't declare pure virtual functions in sanitizer runtimes:
   // __cxa_pure_virtual might be unavailable.
 
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
index 2a7b16d..5088e22 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
@@ -350,8 +350,8 @@ class InternalSymbolizer : public SymbolizerTool {
 
 class POSIXSymbolizer : public Symbolizer {
  public:
-  explicit POSIXSymbolizer(SymbolizerTool *symbolizer_tool)
-      : Symbolizer(), symbolizer_tool_(symbolizer_tool) {}
+  explicit POSIXSymbolizer(IntrusiveList<SymbolizerTool> tools)
+      : Symbolizer(), tools_(tools) {}
 
   SymbolizedStack *SymbolizePC(uptr addr) override {
     BlockingMutexLock l(&mu_);
@@ -362,9 +362,12 @@ class POSIXSymbolizer : public Symbolizer {
       return res;
     // Always fill data about module name and offset.
     res->info.FillModuleInfo(module_name, module_offset);
-    if (symbolizer_tool_) {
+    for (auto iter = Iterator(&tools_); iter.hasNext();) {
+      auto *tool = iter.next();
       SymbolizerScope sym_scope(this);
-      symbolizer_tool_->SymbolizePC(addr, res);
+      if (tool->SymbolizePC(addr, res)) {
+        return res;
+      }
     }
     return res;
   }
@@ -379,9 +382,12 @@ class POSIXSymbolizer : public Symbolizer {
     info->Clear();
     info->module = internal_strdup(module_name);
     info->module_offset = module_offset;
-    if (symbolizer_tool_) {
+    for (auto iter = Iterator(&tools_); iter.hasNext();) {
+      auto *tool = iter.next();
       SymbolizerScope sym_scope(this);
-      symbolizer_tool_->SymbolizeData(addr, info);
+      if (tool->SymbolizeData(addr, info)) {
+        return true;
+      }
     }
     return true;
   }
@@ -393,22 +399,24 @@ class POSIXSymbolizer : public Symbolizer {
   }
 
   bool CanReturnFileLineInfo() override {
-    return symbolizer_tool_ != nullptr;
+    return !tools_.empty();
   }
 
   void Flush() override {
     BlockingMutexLock l(&mu_);
-    if (symbolizer_tool_) {
+    for (auto iter = Iterator(&tools_); iter.hasNext();) {
+      auto *tool = iter.next();
       SymbolizerScope sym_scope(this);
-      symbolizer_tool_->Flush();
+      tool->Flush();
     }
   }
 
   const char *Demangle(const char *name) override {
     BlockingMutexLock l(&mu_);
-    if (symbolizer_tool_) {
+    for (auto iter = Iterator(&tools_); iter.hasNext();) {
+      auto *tool = iter.next();
       SymbolizerScope sym_scope(this);
-      if (const char *demangled = symbolizer_tool_->Demangle(name))
+      if (const char *demangled = tool->Demangle(name))
         return demangled;
     }
     return DemangleCXXABI(name);
@@ -472,7 +480,8 @@ class POSIXSymbolizer : public Symbolizer {
   bool modules_fresh_;
   BlockingMutex mu_;
 
-  SymbolizerTool *const symbolizer_tool_;         // Leaked.
+  typedef IntrusiveList<SymbolizerTool>::Iterator Iterator;
+  IntrusiveList<SymbolizerTool> tools_;
 };
 
 static SymbolizerTool *ChooseSymbolizer(LowLevelAllocator *allocator) {
@@ -507,8 +516,12 @@ static SymbolizerTool *ChooseSymbolizer(LowLevelAllocator *allocator) {
 }
 
 Symbolizer *Symbolizer::PlatformInit() {
-  return new(symbolizer_allocator_)
-      POSIXSymbolizer(ChooseSymbolizer(&symbolizer_allocator_));
+  IntrusiveList<SymbolizerTool> list;
+  list.clear();
+  if (SymbolizerTool *tool = ChooseSymbolizer(&symbolizer_allocator_)) {
+    list.push_back(tool);
+  }
+  return new(symbolizer_allocator_) POSIXSymbolizer(list);
 }
 
 }  // namespace __sanitizer
-- 
2.7.4