[TBAA] Drop support for "old style" scalar TBAA tags

Summary:
We've had support for auto upgrading old style scalar TBAA access
metadata tags into the "new" struct path aware TBAA metadata for 3 years
now.  The only way to actually generate old style TBAA was explicitly
through the IRBuilder API.  I think this is a good time for dropping
support for old style scalar TBAA.

I'm not removing support for textual or bitcode upgrade -- if you have
IR with the old style scalar TBAA tags that go through the AsmParser orf
the bitcode parser before LLVM sees them, they will keep working as
usual.

Note:

  %val = load i32, i32* %ptr, !tbaa !N
  !N = < scalar tbaa node >

is equivalent to

  %val = load i32, i32* %ptr, !tbaa !M
  !N = < scalar tbaa node >
  !M = !{!N, !N, 0}

Reviewers: manmanren, chandlerc, sunfish

Subscribers: mcrosier, llvm-commits, mgorny

Differential Revision: https://reviews.llvm.org/D26229

llvm-svn: 286291

1 files changed, 13 insertions, 0 deletions

diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index a8a1df3e8b4..31a181e8db4 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -391,6 +391,7 @@ private:
   void visitBasicBlock(BasicBlock &BB);
   void visitRangeMetadata(Instruction& I, MDNode* Range, Type* Ty);
   void visitDereferenceableMetadata(Instruction& I, MDNode* MD);
+  void visitTBAAMetadata(Instruction &I, MDNode *MD);
 
   template <class Ty> bool isValidMetadataArray(const MDTuple &N);
 #define HANDLE_SPECIALIZED_MDNODE_LEAF(CLASS) void visit##CLASS(const CLASS &N);
@@ -3658,6 +3659,15 @@ void Verifier::visitDereferenceableMetadata(Instruction& I, MDNode* MD) {
          "dereferenceable_or_null metadata value must be an i64!", &I);
 }
 
+void Verifier::visitTBAAMetadata(Instruction &I, MDNode *MD) {
+  bool IsStructPathTBAA =
+      isa<MDNode>(MD->getOperand(0)) && MD->getNumOperands() >= 3;
+
+  Assert(IsStructPathTBAA,
+         "Old-style TBAA is no longer allowed, use struct-path TBAA instead",
+         &I);
+}
+
 /// verifyInstruction - Verify that an instruction is well formed.
 ///
 void Verifier::visitInstruction(Instruction &I) {
@@ -3793,6 +3803,9 @@ void Verifier::visitInstruction(Instruction &I) {
   if (MDNode *MD = I.getMetadata(LLVMContext::MD_dereferenceable_or_null))
     visitDereferenceableMetadata(I, MD);
 
+  if (MDNode *MD = I.getMetadata(LLVMContext::MD_tbaa))
+    visitTBAAMetadata(I, MD);
+
   if (MDNode *AlignMD = I.getMetadata(LLVMContext::MD_align)) {
     Assert(I.getType()->isPointerTy(), "align applies only to pointer types",
            &I);