[Transforms] Support making mutable versions of new-format TBAA access tags

Differential Revision: https://reviews.llvm.org/D41565

llvm-svn: 322650

1 files changed, 27 insertions, 0 deletions

diff --git a/llvm/lib/IR/MDBuilder.cpp b/llvm/lib/IR/MDBuilder.cpp
index 9d467fb9f6d..c32a989ef2c 100644
--- a/llvm/lib/IR/MDBuilder.cpp
+++ b/llvm/lib/IR/MDBuilder.cpp
@@ -232,6 +232,33 @@ MDNode *MDBuilder::createTBAAAccessTag(MDNode *BaseType, MDNode *AccessType,
   return MDNode::get(Context, {BaseType, AccessType, OffsetNode, SizeNode});
 }
 
+MDNode *MDBuilder::createMutableTBAAAccessTag(MDNode *Tag) {
+  MDNode *BaseType = cast<MDNode>(Tag->getOperand(1));
+  MDNode *AccessType = cast<MDNode>(Tag->getOperand(1));
+  Metadata *OffsetNode = Tag->getOperand(2);
+  uint64_t Offset = mdconst::extract<ConstantInt>(OffsetNode)->getZExtValue();
+
+  bool NewFormat = isa<MDNode>(AccessType->getOperand(0));
+
+  // See if the tag is already mutable.
+  unsigned ImmutabilityFlagOp = NewFormat ? 4 : 3;
+  if (Tag->getNumOperands() <= ImmutabilityFlagOp)
+    return Tag;
+
+  // If Tag is already mutable then return it.
+  Metadata *ImmutabilityFlagNode = Tag->getOperand(ImmutabilityFlagOp);
+  if (!mdconst::extract<ConstantInt>(ImmutabilityFlagNode)->getValue())
+    return Tag;
+
+  // Otherwise, create another node.
+  if (!NewFormat)
+    return createTBAAStructTagNode(BaseType, AccessType, Offset);
+
+  Metadata *SizeNode = Tag->getOperand(3);
+  uint64_t Size = mdconst::extract<ConstantInt>(SizeNode)->getZExtValue();
+  return createTBAAAccessTag(BaseType, AccessType, Offset, Size);
+}
+
 MDNode *MDBuilder::createIrrLoopHeaderWeight(uint64_t Weight) {
   SmallVector<Metadata *, 2> Vals(2);
   Vals[0] = createString("loop_header_weight");