Remangle intrinsics names when types are renamed

This is a resubmittion of previously reverted rL273568.

This is a fix for the problem mentioned in "LTO and intrinsics mangling" llvm-dev mail thread:
http://lists.llvm.org/pipermail/llvm-dev/2016-April/098387.html

Reviewers: mehdi_amini, reames

Differential Revision: http://reviews.llvm.org/D19373

llvm-svn: 273686

1 files changed, 34 insertions, 0 deletions

diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index 29ed68a2c5e..0da9b98258c 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -1080,6 +1080,40 @@ Intrinsic::matchIntrinsicVarArg(bool isVarArg,
   return true;
 }
 
+Optional<Function*> Intrinsic::remangleIntrinsicFunction(Function *F) {
+  Intrinsic::ID ID = F->getIntrinsicID();
+  if (!ID)
+    return None;
+
+  FunctionType *FTy = F->getFunctionType();
+  // Accumulate an array of overloaded types for the given intrinsic
+  SmallVector<Type *, 4> ArgTys;
+  {
+    SmallVector<Intrinsic::IITDescriptor, 8> Table;
+    getIntrinsicInfoTableEntries(ID, Table);
+    ArrayRef<Intrinsic::IITDescriptor> TableRef = Table;
+
+    // If we encounter any problems matching the signature with the descriptor
+    // just give up remangling. It's up to verifier to report the discrepancy.
+    if (Intrinsic::matchIntrinsicType(FTy->getReturnType(), TableRef, ArgTys))
+      return None;
+    for (auto Ty : FTy->params())
+      if (Intrinsic::matchIntrinsicType(Ty, TableRef, ArgTys))
+        return None;
+    if (Intrinsic::matchIntrinsicVarArg(FTy->isVarArg(), TableRef))
+      return None;
+  }
+
+  StringRef Name = F->getName();
+  if (Name == Intrinsic::getName(ID, ArgTys))
+    return None;
+
+  auto NewDecl = Intrinsic::getDeclaration(F->getParent(), ID, ArgTys);
+  NewDecl->setCallingConv(F->getCallingConv());
+  assert(NewDecl->getFunctionType() == FTy && "Shouldn't change the signature");
+  return NewDecl;
+}
+
 /// hasAddressTaken - returns true if there are any uses of this function
 /// other than direct calls or invokes to it.
 bool Function::hasAddressTaken(const User* *PutOffender) const {