[llvm] [NFC][Cloning] Make DifferentModule case more obvious in CollectDebugInfoForCloning (PR #129146)

[Artem Pianykh via llvm-commits]

https://github.com/artempyanykh updated https://github.com/llvm/llvm-project/pull/129146

>From 46dfb15d8e6d557e09b98b1e917ccf543bd0ad11 Mon Sep 17 00:00:00 2001
From: Artem Pianykh <arr at fb.com>
Date: Tue, 25 Feb 2025 10:20:06 -0800
Subject: [PATCH] [NFC][Cloning] Make DifferentModule case more obvious in
 CollectDebugInfoForCloning

Summary:
This should be behaviorally equivalent. DIFinder is only used when
cloning into a DifferentModule as part of llvm.dbg.cu update in
CloneFunctionInto.

Test Plan:
ninja check-llvm-unit check-llvm

stack-info: PR: https://github.com/llvm/llvm-project/pull/129146, branch: users/artempyanykh/fast-coro-upstream-part2-take2/4
---
 llvm/lib/Transforms/Utils/CloneFunction.cpp | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/Transforms/Utils/CloneFunction.cpp b/llvm/lib/Transforms/Utils/CloneFunction.cpp
index e03c5c27b5ac1..dd1b4fe718053 100644
--- a/llvm/lib/Transforms/Utils/CloneFunction.cpp
+++ b/llvm/lib/Transforms/Utils/CloneFunction.cpp
@@ -147,8 +147,10 @@ void llvm::CloneFunctionAttributesInto(Function *NewFunc,
 DISubprogram *llvm::CollectDebugInfoForCloning(const Function &F,
                                                CloneFunctionChangeType Changes,
                                                DebugInfoFinder &DIFinder) {
-  // CloneModule takes care of cloning debug info.
-  if (Changes == CloneFunctionChangeType::ClonedModule)
+  // CloneModule takes care of cloning debug info for ClonedModule. Cloning into
+  // DifferentModule is taken care of separately in ClonedFunctionInto as part
+  // of llvm.dbg.cu update.
+  if (Changes >= CloneFunctionChangeType::DifferentModule)
     return nullptr;
 
   DISubprogram *SPClonedWithinModule = nullptr;
@@ -362,6 +364,10 @@ void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
   SmallPtrSet<const void *, 8> Visited;
   for (auto *Operand : NMD->operands())
     Visited.insert(Operand);
+
+  // Collect and clone all the compile units referenced from the instructions in
+  // the function (e.g. as a scope).
+  collectDebugInfoFromInstructions(*OldFunc, DIFinder);
   for (auto *Unit : DIFinder.compile_units()) {
     MDNode *MappedUnit =
         MapMetadata(Unit, VMap, RF_None, TypeMapper, Materializer);