whitequark.patch

diff --git a/lib/Transforms/IPO/MergeFunctions.cpp b/lib/Transforms/IPO/MergeFunctions.cpp
index e0bb0eb42b5..794e502d468 100644
--- a/lib/Transforms/IPO/MergeFunctions.cpp
+++ b/lib/Transforms/IPO/MergeFunctions.cpp
@@ -27,7 +27,7 @@
 // -- We define Function* container class with custom "operator<" (FunctionPtr).
 // -- "FunctionPtr" instances are stored in std::set collection, so every
 //    std::set::insert operation will give you result in log(N) time.
-// 
+//
 // As an optimization, a hash of the function structure is calculated first, and
 // two functions are only compared if they have the same hash. This hash is
 // cheap to compute, and has the property that if function F == G according to
@@ -333,7 +333,7 @@ bool MergeFunctions::runOnModule(Module &M) {
   for (Function &Func : M) {
     if (!Func.isDeclaration() && !Func.hasAvailableExternallyLinkage()) {
       HashedFuncs.push_back({FunctionComparator::functionHash(Func), &Func});
-    } 
+    }
   }
 
   std::stable_sort(
@@ -352,7 +352,7 @@ bool MergeFunctions::runOnModule(Module &M) {
       Deferred.push_back(WeakVH(I->second));
     }
   }
-  
+
   do {
     std::vector<WeakVH> Worklist;
     Deferred.swap(Worklist);
@@ -465,8 +465,15 @@ static Value *createCast(IRBuilder<> &Builder, Value *V, Type *DestTy) {
 // of G with bitcast(F). Deletes G.
 void MergeFunctions::writeThunk(Function *F, Function *G) {
   if (!G->isInterposable()) {
-    // Redirect direct callers of G to F.
-    replaceDirectCallers(G, F);
+    if (G->hasGlobalUnnamedAddr()) {
+      // If G's address is not significant, replace it entirely.
+      Constant *BitcastF = ConstantExpr::getBitCast(F, G->getType());
+      G->replaceAllUsesWith(BitcastF);
+    } else {
+      // Redirect direct callers of G to F. (See note on MergeFunctionsPDI
+      // above).
+      replaceDirectCallers(G, F);
+    }
   }
 
   // If G was internal then we may have replaced all uses of G with F. If so,
@@ -476,6 +483,16 @@ void MergeFunctions::writeThunk(Function *F, Function *G) {
     return;
   }
 
+  // Don't merge tiny functions using a thunk, since it can just end up
+  // making the function larger.
+  if (F->size() == 1) {
+    if (F->front().size() <= 2) {
+      DEBUG(dbgs() << "writeThunk: " << F->getName()
+                   << " is too small to bother creating a thunk for\n");
+      return;
+    }
+  }
+
   Function *NewG = Function::Create(G->getFunctionType(), G->getLinkage(), "",
                                     G->getParent());
   BasicBlock *BB = BasicBlock::Create(F->getContext(), "", NewG);
@@ -562,11 +579,11 @@ void MergeFunctions::replaceFunctionInTree(const FunctionNode &FN,
   Function *F = FN.getFunc();
   assert(FunctionComparator(F, G, &GlobalNumbers).compare() == 0 &&
          "The two functions must be equal");
-  
+
   auto I = FNodesInTree.find(F);
   assert(I != FNodesInTree.end() && "F should be in FNodesInTree");
   assert(FNodesInTree.count(G) == 0 && "FNodesInTree should not contain G");
-  
+
   FnTreeType::iterator IterToFNInFnTree = I->second;
   assert(&(*IterToFNInFnTree) == &FN && "F should map to FN in FNodesInTree.");
   // Remove F -> FN and insert G -> FN
@@ -591,18 +608,6 @@ bool MergeFunctions::insert(Function *NewFunction) {
 
   const FunctionNode &OldF = *Result.first;
 
-  // Don't merge tiny functions, since it can just end up making the function
-  // larger.
-  // FIXME: Should still merge them if they are unnamed_addr and produce an
-  // alias.
-  if (NewFunction->size() == 1) {
-    if (NewFunction->front().size() <= 2) {
-      DEBUG(dbgs() << NewFunction->getName()
-                   << " is to small to bother merging\n");
-      return false;
-    }
-  }
-
   // Impose a total order (by name) on the replacement of functions. This is
   // important when operating on more than one module independently to prevent
   // cycles of thunks calling each other when the modules are linked together.
diff --git a/test/Transforms/MergeFunc/merge-small-unnamed-addr.ll b/test/Transforms/MergeFunc/merge-small-unnamed-addr.ll
new file mode 100644
index 00000000000..256f6864761
--- /dev/null
+++ b/test/Transforms/MergeFunc/merge-small-unnamed-addr.ll
@@ -0,0 +1,14 @@
+; RUN: opt -S -mergefunc < %s | FileCheck %s
+
+; CHECK-NOT: @b
+
+@x = constant { void ()*, void ()* } { void ()* @a, void ()* @b }
+; CHECK: { void ()* @a, void ()* @a }
+
+define internal void @a() unnamed_addr {
+  ret void
+}
+
+define internal void @b() unnamed_addr {
+  ret void
+}
diff --git a/test/Transforms/MergeFunc/merge-unnamed-addr-bitcast.ll b/test/Transforms/MergeFunc/merge-unnamed-addr-bitcast.ll
new file mode 100644
index 00000000000..8a9a9e67551
--- /dev/null
+++ b/test/Transforms/MergeFunc/merge-unnamed-addr-bitcast.ll
@@ -0,0 +1,30 @@
+; RUN: opt -S -mergefunc < %s | FileCheck %s
+
+%A = type { i32 }
+%B = type { i32 }
+
+; CHECK-NOT: @b
+
+@x = constant { i32 (i32)*, i32 (i32)* } 
+  { i32 (i32)* bitcast (i32 (%A)* @a to i32 (i32)*), 
+    i32 (i32)* bitcast (i32 (%B)* @b to i32 (i32)*) }
+; CHECK: { i32 (i32)* bitcast (i32 (%A)* @a to i32 (i32)*), i32 (i32)* bitcast (i32 (%A)* @a to i32 (i32)*) }
+
+define internal i32 @a(%A) unnamed_addr {
+  extractvalue %A %0, 0
+  xor i32 %2, 0
+  ret i32 %3
+}
+
+define internal i32 @b(%B) unnamed_addr {
+  extractvalue %B %0, 0
+  xor i32 %2, 0
+  ret i32 %3
+}
+
+define i32 @c(i32) {
+  insertvalue %B undef, i32 %0, 0
+  call i32 @b(%B %2)
+; CHECK: call i32 bitcast (i32 (%A)* @a to i32 (%B)*)(%B %2)
+  ret i32 %3
+}
diff --git a/test/Transforms/MergeFunc/merge-unnamed-addr.ll b/test/Transforms/MergeFunc/merge-unnamed-addr.ll
new file mode 100644
index 00000000000..cb34d43c08f
--- /dev/null
+++ b/test/Transforms/MergeFunc/merge-unnamed-addr.ll
@@ -0,0 +1,18 @@
+; RUN: opt -S -mergefunc < %s | FileCheck %s
+
+; CHECK-NOT: @b
+
+@x = constant { i32 (i32)*, i32 (i32)* } { i32 (i32)* @a, i32 (i32)* @b }
+; CHECK: { i32 (i32)* @a, i32 (i32)* @a }
+
+define internal i32 @a(i32 %a) unnamed_addr {
+  %b = xor i32 %a, 0
+  %c = xor i32 %b, 0
+  ret i32 %c
+}
+
+define internal i32 @b(i32 %a) unnamed_addr {
+  %b = xor i32 %a, 0
+  %c = xor i32 %b, 0
+  ret i32 %c
+}
diff --git a/test/Transforms/MergeFunc/no-merge-small.ll b/test/Transforms/MergeFunc/no-merge-small.ll
new file mode 100644
index 00000000000..888d42caeb8
--- /dev/null
+++ b/test/Transforms/MergeFunc/no-merge-small.ll
@@ -0,0 +1,11 @@
+; RUN: opt -S -mergefunc < %s | FileCheck %s
+
+; CHECK: @a
+define void @a() {
+  ret void
+}
+
+; CHECK: @b
+define void @b() {
+  ret void
+}