3 files changed, 21 insertions, 0 deletions
diff --git a/llvm/lib/IR/DebugInfoMetadata.cpp b/llvm/lib/IR/DebugInfoMetadata.cpp
index e8a58f1..0973fcf 100644
--- a/llvm/lib/IR/DebugInfoMetadata.cpp
+++ b/llvm/lib/IR/DebugInfoMetadata.cpp
@@ -74,6 +74,9 @@ DILocation::DILocation(LLVMContext &C, StorageType Storage, unsigned Line,
 #ifdef EXPERIMENTAL_KEY_INSTRUCTIONS
   assert(AtomRank <= 7 && "AtomRank number should fit in 3 bits");
 #endif
+  if (AtomGroup)
+    C.updateDILocationAtomGroupWaterline(AtomGroup + 1);
+
   assert((MDs.size() == 1 || MDs.size() == 2) &&
          "Expected a scope and optional inlined-at");
   // Set line and column.
diff --git a/llvm/lib/IR/LLVMContext.cpp b/llvm/lib/IR/LLVMContext.cpp
index 447e5d9..57532cd 100644
--- a/llvm/lib/IR/LLVMContext.cpp
+++ b/llvm/lib/IR/LLVMContext.cpp
@@ -377,3 +377,11 @@ StringRef LLVMContext::getDefaultTargetFeatures() {
 void LLVMContext::setDefaultTargetFeatures(StringRef Features) {
   pImpl->DefaultTargetFeatures = Features;
 }
+
+void LLVMContext::updateDILocationAtomGroupWaterline(uint64_t V) {
+  pImpl->NextAtomGroup = std::max(pImpl->NextAtomGroup, V);
+}
+
+uint64_t LLVMContext::incNextDILocationAtomGroup() {
+  return pImpl->NextAtomGroup++;
+}
diff --git a/llvm/lib/IR/LLVMContextImpl.h b/llvm/lib/IR/LLVMContextImpl.h
index 5c2b5cd..21f5c06 100644
--- a/llvm/lib/IR/LLVMContextImpl.h
+++ b/llvm/lib/IR/LLVMContextImpl.h
@@ -1880,6 +1880,16 @@ public:
 
   std::string DefaultTargetCPU;
   std::string DefaultTargetFeatures;
+
+  /// The next available source atom group number. The front end is responsible
+  /// for assigning source atom numbers, but certain optimisations need to
+  /// assign new group numbers to a set of instructions. Most often code
+  /// duplication optimisations like loop unroll. Tracking a global maximum
+  /// value means we can know (cheaply) we're never using a group number that's
+  /// already used within this function.
+  ///
+  /// Start a 1 because 0 means the source location isn't part of an atom group.
+  uint64_t NextAtomGroup = 1;
 };
 
 } // end namespace llvm