AutoUpgrade: upgrade from scalar TBAA format to struct-path aware TBAA format.

We treat TBAA tags as struct-path aware TBAA format when the first operand
is a MDNode and the tag has 3 or more operands.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191593 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 27 insertions, 0 deletions

diff --git a/lib/IR/AutoUpgrade.cpp b/lib/IR/AutoUpgrade.cpp
index a4f5289e5e..9839b0674e 100644
--- a/lib/IR/AutoUpgrade.cpp
+++ b/lib/IR/AutoUpgrade.cpp
@@ -391,3 +391,30 @@ void llvm::UpgradeCallsToIntrinsic(Function* F) {
   }
 }
 
+void llvm::UpgradeInstWithTBAATag(Instruction *I) {
+  MDNode *MD = I->getMetadata(LLVMContext::MD_tbaa);
+  assert(MD && "UpgradeInstWithTBAATag should have a TBAA tag");
+  // Check if the tag uses struct-path aware TBAA format.
+  if (isa<MDNode>(MD->getOperand(0)) && MD->getNumOperands() >= 3)
+    return;
+
+  if (MD->getNumOperands() == 3) {
+    Value *Elts[] = {
+      MD->getOperand(0),
+      MD->getOperand(1)
+    };
+    MDNode *ScalarType = MDNode::get(I->getContext(), Elts);
+    // Create a MDNode <ScalarType, ScalarType, offset 0, const>
+    Value *Elts2[] = {
+      ScalarType, ScalarType,
+      Constant::getNullValue(Type::getInt64Ty(I->getContext())),
+      MD->getOperand(2)
+    };
+    I->setMetadata(LLVMContext::MD_tbaa, MDNode::get(I->getContext(), Elts2));
+  } else {
+    // Create a MDNode <MD, MD, offset 0>
+    Value *Elts[] = {MD, MD,
+      Constant::getNullValue(Type::getInt64Ty(I->getContext()))};
+    I->setMetadata(LLVMContext::MD_tbaa, MDNode::get(I->getContext(), Elts));
+  }
+}