[KeyInstr][debugify] Add --debugify-atoms to add key instructions metadata (#133483)

RFC:
https://discourse.llvm.org/t/rfc-improving-is-stmt-placement-for-better-interactive-debugging/82668

1 files changed, 9 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/Utils/Debugify.cpp b/llvm/lib/Transforms/Utils/Debugify.cpp
index d67a563..3e323cc 100644
--- a/llvm/lib/Transforms/Utils/Debugify.cpp
+++ b/llvm/lib/Transforms/Utils/Debugify.cpp
@@ -35,6 +35,8 @@ using namespace llvm;
 
 namespace {
 
+cl::opt<bool> ApplyAtomGroups("debugify-atoms", cl::init(false));
+
 cl::opt<bool> Quiet("debugify-quiet",
                     cl::desc("Suppress verbose debugify output"));
 
@@ -142,8 +144,13 @@ bool llvm::applyDebugifyMetadata(
 
     for (BasicBlock &BB : F) {
       // Attach debug locations.
-      for (Instruction &I : BB)
-        I.setDebugLoc(DILocation::get(Ctx, NextLine++, 1, SP));
+      for (Instruction &I : BB) {
+        uint64_t AtomGroup = ApplyAtomGroups ? NextLine : 0;
+        uint8_t AtomRank = ApplyAtomGroups ? 1 : 0;
+        uint64_t Line = NextLine++;
+        I.setDebugLoc(DILocation::get(Ctx, Line, 1, SP, nullptr, false,
+                                      AtomGroup, AtomRank));
+      }
 
       if (DebugifyLevel < Level::LocationsAndVariables)
         continue;