From 3fcd3669e3dc7c5ba72d3bfceef42b2f833254ec Mon Sep 17 00:00:00 2001
From: Lang Hames <lhames@gmail.com>
Date: Wed, 8 Jun 2022 16:48:15 -0700
Subject: [PATCH] [ORC] Add an output stream operator for SymbolStringPool.

Handy for checking string pool state, e.g. when debugging dangling-pool-entry
errors.
---
 llvm/include/llvm/ExecutionEngine/Orc/DebugUtils.h   |  3 +++
 .../llvm/ExecutionEngine/Orc/SymbolStringPool.h      |  7 +++++++
 llvm/lib/ExecutionEngine/Orc/DebugUtils.cpp          |  7 +++++++
 .../ExecutionEngine/Orc/SymbolStringPoolTest.cpp     | 12 ++++++++++++
 4 files changed, 29 insertions(+)

diff --git a/llvm/include/llvm/ExecutionEngine/Orc/DebugUtils.h b/llvm/include/llvm/ExecutionEngine/Orc/DebugUtils.h
index 7eb98dfc741e..c4ef06f1fbc6 100644
--- a/llvm/include/llvm/ExecutionEngine/Orc/DebugUtils.h
+++ b/llvm/include/llvm/ExecutionEngine/Orc/DebugUtils.h
@@ -92,6 +92,9 @@ raw_ostream &operator<<(raw_ostream &OS, const SymbolState &S);
 /// Render a LookupKind.
 raw_ostream &operator<<(raw_ostream &OS, const LookupKind &K);
 
+/// Dump a SymbolStringPool. Useful for debugging dangling-pointer crashes.
+raw_ostream &operator<<(raw_ostream &OS, const SymbolStringPool &SSP);
+
 /// A function object that can be used as an ObjectTransformLayer transform
 /// to dump object files to disk at a specified path.
 class DumpObjects {
diff --git a/llvm/include/llvm/ExecutionEngine/Orc/SymbolStringPool.h b/llvm/include/llvm/ExecutionEngine/Orc/SymbolStringPool.h
index 63abb196ba49..7e433965c922 100644
--- a/llvm/include/llvm/ExecutionEngine/Orc/SymbolStringPool.h
+++ b/llvm/include/llvm/ExecutionEngine/Orc/SymbolStringPool.h
@@ -19,6 +19,9 @@
 #include <mutex>
 
 namespace llvm {
+
+class raw_ostream;
+
 namespace orc {
 
 class SymbolStringPtr;
@@ -26,6 +29,10 @@ class SymbolStringPtr;
 /// String pool for symbol names used by the JIT.
 class SymbolStringPool {
   friend class SymbolStringPtr;
+
+  // Implemented in DebugUtils.h.
+  friend raw_ostream &operator<<(raw_ostream &OS, const SymbolStringPool &SSP);
+
 public:
   /// Destroy a SymbolStringPool.
   ~SymbolStringPool();
diff --git a/llvm/lib/ExecutionEngine/Orc/DebugUtils.cpp b/llvm/lib/ExecutionEngine/Orc/DebugUtils.cpp
index 5b386a458f1f..028bd245fb55 100644
--- a/llvm/lib/ExecutionEngine/Orc/DebugUtils.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/DebugUtils.cpp
@@ -297,6 +297,13 @@ raw_ostream &operator<<(raw_ostream &OS, const SymbolState &S) {
   llvm_unreachable("Invalid state");
 }
 
+raw_ostream &operator<<(raw_ostream &OS, const SymbolStringPool &SSP) {
+  std::lock_guard<std::mutex> Lock(SSP.PoolMutex);
+  for (auto &KV : SSP.Pool)
+    OS << KV.first() << ": " << KV.second << "\n";
+  return OS;
+}
+
 DumpObjects::DumpObjects(std::string DumpDir, std::string IdentifierOverride)
     : DumpDir(std::move(DumpDir)),
       IdentifierOverride(std::move(IdentifierOverride)) {
diff --git a/llvm/unittests/ExecutionEngine/Orc/SymbolStringPoolTest.cpp b/llvm/unittests/ExecutionEngine/Orc/SymbolStringPoolTest.cpp
index a68da0be9606..aab465a31257 100644
--- a/llvm/unittests/ExecutionEngine/Orc/SymbolStringPoolTest.cpp
+++ b/llvm/unittests/ExecutionEngine/Orc/SymbolStringPoolTest.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ExecutionEngine/Orc/SymbolStringPool.h"
+#include "llvm/ExecutionEngine/Orc/DebugUtils.h"
 #include "gtest/gtest.h"
 
 using namespace llvm;
@@ -50,4 +51,15 @@ TEST(SymbolStringPool, ClearDeadEntries) {
   EXPECT_TRUE(SP.empty()) << "pool should be empty";
 }
 
+TEST(SymbolStringPool, DebugDump) {
+  SymbolStringPool SP;
+  auto A1 = SP.intern("a");
+  auto A2 = A1;
+  auto B = SP.intern("b");
+
+  std::string DumpString;
+  raw_string_ostream(DumpString) << SP;
+
+  EXPECT_EQ(DumpString, "a: 2\nb: 1\n");
+}
 }