From bd10af96bdd91eb9a0c18e9b0c005290ec958f57 Mon Sep 17 00:00:00 2001
From: Nick Lewycky <nicholas@mxc.ca>
Date: Fri, 8 Apr 2011 22:19:52 +0000
Subject: [PATCH] Add a function for profiling to run at shutdown. Unlike the
 existing API, this can be used even when main() isn't present in the Module,
 but it means that you don't get to read argv[].

llvm-svn: 129163
---
 .../Instrumentation/ProfilingUtils.cpp        | 39 ++++++++++++++++++-
 .../Instrumentation/ProfilingUtils.h          |  4 +-
 2 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/Transforms/Instrumentation/ProfilingUtils.cpp b/llvm/lib/Transforms/Instrumentation/ProfilingUtils.cpp
index b57bbf60a07a..26b01e8c2fd3 100644
--- a/llvm/lib/Transforms/Instrumentation/ProfilingUtils.cpp
+++ b/llvm/lib/Transforms/Instrumentation/ProfilingUtils.cpp
@@ -121,8 +121,7 @@ void llvm::IncrementCounterInBlock(BasicBlock *BB, unsigned CounterNum,
   Indices[0] = Constant::getNullValue(Type::getInt32Ty(Context));
   Indices[1] = ConstantInt::get(Type::getInt32Ty(Context), CounterNum);
   Constant *ElementPtr =
-    ConstantExpr::getGetElementPtr(CounterArray, &Indices[0],
-                                          Indices.size());
+    ConstantExpr::getGetElementPtr(CounterArray, &Indices[0], Indices.size());
 
   // Load, increment and store the value back.
   Value *OldVal = new LoadInst(ElementPtr, "OldFuncCounter", InsertPos);
@@ -131,3 +130,39 @@ void llvm::IncrementCounterInBlock(BasicBlock *BB, unsigned CounterNum,
                                          "NewFuncCounter", InsertPos);
   new StoreInst(NewVal, ElementPtr, InsertPos);
 }
+
+void llvm::InsertProfilingShutdownCall(Function *Callee, Module *Mod) {
+  // llvm.global_dtors is an array of type { i32, void ()* }. Prepare those
+  // types.
+  const Type *GlobalDtorElems[2] = {
+    Type::getInt32Ty(Mod->getContext()),
+    FunctionType::get(Type::getVoidTy(Mod->getContext()), false)->getPointerTo()
+  };
+  const StructType *GlobalDtorElemTy =
+      StructType::get(Mod->getContext(), GlobalDtorElems, false);
+
+  // Construct the new element we'll be adding.
+  Constant *Elem[2] = {
+    ConstantInt::get(Type::getInt32Ty(Mod->getContext()), 65535),
+    ConstantExpr::getBitCast(Callee, GlobalDtorElems[1])
+  };
+
+  // If llvm.global_dtors exists, make a copy of the things in its list and
+  // delete it, to replace it with one that has a larger array type.
+  std::vector<Constant *> dtors;
+  if (GlobalVariable *GlobalDtors = Mod->getNamedGlobal("llvm.global_dtors")) {
+    ConstantArray *InitList =
+        cast<ConstantArray>(GlobalDtors->getInitializer());
+    for (unsigned i = 0, e = InitList->getType()->getNumElements(); i != e; ++i)
+      dtors.push_back(cast<Constant>(InitList->getOperand(i)));
+    GlobalDtors->eraseFromParent();
+  }
+
+  // Build up llvm.global_dtors with our new item in it.
+  GlobalVariable *GlobalDtors = new GlobalVariable(
+      *Mod, ArrayType::get(GlobalDtorElemTy, 1), false,
+      GlobalValue::AppendingLinkage, NULL, "llvm.global_dtors");
+  dtors.push_back(ConstantStruct::get(Mod->getContext(), Elem, 2, false));
+  GlobalDtors->setInitializer(ConstantArray::get(
+      cast<ArrayType>(GlobalDtors->getType()->getElementType()), dtors));
+}
diff --git a/llvm/lib/Transforms/Instrumentation/ProfilingUtils.h b/llvm/lib/Transforms/Instrumentation/ProfilingUtils.h
index a76e3576e1ca..09b22171ff04 100644
--- a/llvm/lib/Transforms/Instrumentation/ProfilingUtils.h
+++ b/llvm/lib/Transforms/Instrumentation/ProfilingUtils.h
@@ -18,9 +18,10 @@
 #define PROFILINGUTILS_H
 
 namespace llvm {
+  class BasicBlock;
   class Function;
   class GlobalValue;
-  class BasicBlock;
+  class Module;
   class PointerType;
 
   void InsertProfilingInitCall(Function *MainFn, const char *FnName,
@@ -29,6 +30,7 @@ namespace llvm {
   void IncrementCounterInBlock(BasicBlock *BB, unsigned CounterNum,
                                GlobalValue *CounterArray,
                                bool beginning = true);
+  void InsertProfilingShutdownCall(Function *Callee, Module *Mod);
 }
 
 #endif