[AllocToken, Clang] Implement TypeHashPointerSplit mode (#156840)

Implement the TypeHashPointerSplit mode: This mode assigns a token ID
based on the hash of the allocated type's name, where the top half
ID-space is reserved for types that contain pointers and the bottom half
for types that do not contain pointers.

This mode with max tokens of 2 (`-falloc-token-max=2`) may also
be valuable for heap hardening strategies that simply separate pointer
types from non-pointer types.

Make it the new default mode.

Link: https://discourse.llvm.org/t/rfc-a-framework-for-allocator-partitioning-hints/87434

---

This change is part of the following series:
  1. https://github.com/llvm/llvm-project/pull/160131
  2. https://github.com/llvm/llvm-project/pull/156838
  3. https://github.com/llvm/llvm-project/pull/162098
  4. https://github.com/llvm/llvm-project/pull/162099
  5. https://github.com/llvm/llvm-project/pull/156839
  6. https://github.com/llvm/llvm-project/pull/156840
  7. https://github.com/llvm/llvm-project/pull/156841
  8. https://github.com/llvm/llvm-project/pull/156842

1 files changed, 3 insertions, 1 deletions

diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index 71a8a38..c9ff86b 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -5398,8 +5398,10 @@ void Verifier::visitCapturesMetadata(Instruction &I, const MDNode *Captures) {
 
 void Verifier::visitAllocTokenMetadata(Instruction &I, MDNode *MD) {
   Check(isa<CallBase>(I), "!alloc_token should only exist on calls", &I);
-  Check(MD->getNumOperands() == 1, "!alloc_token must have 1 operand", MD);
+  Check(MD->getNumOperands() == 2, "!alloc_token must have 2 operands", MD);
   Check(isa<MDString>(MD->getOperand(0)), "expected string", MD);
+  Check(mdconst::dyn_extract_or_null<ConstantInt>(MD->getOperand(1)),
+        "expected integer constant", MD);
 }
 
 /// verifyInstruction - Verify that an instruction is well formed.