[ModuleUtils] Add transformGlobal{C,D}tors (#101757)

For #101772

1 files changed, 44 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Utils/ModuleUtils.cpp b/llvm/lib/Transforms/Utils/ModuleUtils.cpp
index 1222791..309cf8e 100644
--- a/llvm/lib/Transforms/Utils/ModuleUtils.cpp
+++ b/llvm/lib/Transforms/Utils/ModuleUtils.cpp
@@ -79,6 +79,50 @@ void llvm::appendToGlobalDtors(Module &M, Function *F, int Priority, Constant *D
   appendToGlobalArray("llvm.global_dtors", M, F, Priority, Data);
 }
 
+static void transformGlobalArray(StringRef ArrayName, Module &M,
+                                 const GlobalCtorTransformFn &Fn) {
+  GlobalVariable *GVCtor = M.getNamedGlobal(ArrayName);
+  if (!GVCtor)
+    return;
+
+  IRBuilder<> IRB(M.getContext());
+  SmallVector<Constant *, 16> CurrentCtors;
+  bool Changed = false;
+  StructType *EltTy =
+      cast<StructType>(GVCtor->getValueType()->getArrayElementType());
+  if (Constant *Init = GVCtor->getInitializer()) {
+    CurrentCtors.reserve(Init->getNumOperands());
+    for (Value *OP : Init->operands()) {
+      Constant *C = cast<Constant>(OP);
+      Constant *NewC = Fn(C);
+      Changed |= (!NewC || NewC != C);
+      if (NewC)
+        CurrentCtors.push_back(NewC);
+    }
+  }
+  if (!Changed)
+    return;
+
+  GVCtor->eraseFromParent();
+
+  // Create a new initializer.
+  ArrayType *AT = ArrayType::get(EltTy, CurrentCtors.size());
+  Constant *NewInit = ConstantArray::get(AT, CurrentCtors);
+
+  // Create the new global variable and replace all uses of
+  // the old global variable with the new one.
+  (void)new GlobalVariable(M, NewInit->getType(), false,
+                           GlobalValue::AppendingLinkage, NewInit, ArrayName);
+}
+
+void llvm::transformGlobalCtors(Module &M, const GlobalCtorTransformFn &Fn) {
+  transformGlobalArray("llvm.global_ctors", M, Fn);
+}
+
+void llvm::transformGlobalDtors(Module &M, const GlobalCtorTransformFn &Fn) {
+  transformGlobalArray("llvm.global_dtors", M, Fn);
+}
+
 static void collectUsedGlobals(GlobalVariable *GV,
                                SmallSetVector<Constant *, 16> &Init) {
   if (!GV || !GV->hasInitializer())