[llvm] [NFC][Cloning] Add a helper to collect debug info from instructions (PR #129145)

[Artem Pianykh via llvm-commits]

https://github.com/artempyanykh updated https://github.com/llvm/llvm-project/pull/129145

>From 336c0203871da8d76dc20dd8fdd6c2e2a8cd52f6 Mon Sep 17 00:00:00 2001
From: Artem Pianykh <arr at fb.com>
Date: Tue, 25 Feb 2025 09:55:02 -0800
Subject: [PATCH 1/3] [NFC][Cloning] Make ClonedModule case more obvious in
 CollectDebugInfoForCloning

Summary:
The code's behavior is unchanged, but it's more obvious right now.

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

stack-info: PR: https://github.com/llvm/llvm-project/pull/129143, branch: users/artempyanykh/fast-coro-upstream-part2-take2/1
---
 llvm/lib/Transforms/Utils/CloneFunction.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/llvm/lib/Transforms/Utils/CloneFunction.cpp b/llvm/lib/Transforms/Utils/CloneFunction.cpp
index 58d400ac396be..9267930027c04 100644
--- a/llvm/lib/Transforms/Utils/CloneFunction.cpp
+++ b/llvm/lib/Transforms/Utils/CloneFunction.cpp
@@ -135,6 +135,10 @@ 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)
+    return nullptr;
+
   DISubprogram *SPClonedWithinModule = nullptr;
   if (Changes < CloneFunctionChangeType::DifferentModule) {
     SPClonedWithinModule = F.getSubprogram();
@@ -143,7 +147,7 @@ DISubprogram *llvm::CollectDebugInfoForCloning(const Function &F,
     DIFinder.processSubprogram(SPClonedWithinModule);
 
   const Module *M = F.getParent();
-  if (Changes != CloneFunctionChangeType::ClonedModule && M) {
+  if (M) {
     // Inspect instructions to process e.g. DILexicalBlocks of inlined functions
     for (const auto &I : instructions(F))
       DIFinder.processInstruction(*M, I);

>From 7888809b93cf57d37c5517016c5206314a94bc42 Mon Sep 17 00:00:00 2001
From: Artem Pianykh <arr at fb.com>
Date: Tue, 25 Feb 2025 10:29:56 -0800
Subject: [PATCH 2/3] [NFC][Cloning] Simplify the flow in
 FindDebugInfoToIdentityMap

Summary:
The new flow should make it more clear what is happening in cases of
Different of Cloned modules.

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

stack-info: PR: https://github.com/llvm/llvm-project/pull/129144, branch: users/artempyanykh/fast-coro-upstream-part2-take2/2
---
 llvm/lib/Transforms/Utils/CloneFunction.cpp | 34 ++++++++++-----------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/llvm/lib/Transforms/Utils/CloneFunction.cpp b/llvm/lib/Transforms/Utils/CloneFunction.cpp
index 9267930027c04..7a309f7390c77 100644
--- a/llvm/lib/Transforms/Utils/CloneFunction.cpp
+++ b/llvm/lib/Transforms/Utils/CloneFunction.cpp
@@ -160,32 +160,32 @@ MetadataSetTy
 llvm::FindDebugInfoToIdentityMap(CloneFunctionChangeType Changes,
                                  DebugInfoFinder &DIFinder,
                                  DISubprogram *SPClonedWithinModule) {
+  if (Changes >= CloneFunctionChangeType::DifferentModule)
+    return {};
+
+  if (DIFinder.subprogram_count() == 0)
+    assert(!SPClonedWithinModule &&
+           "Subprogram should be in DIFinder->subprogram_count()...");
+
   MetadataSetTy MD;
 
-  if (Changes < CloneFunctionChangeType::DifferentModule &&
-      DIFinder.subprogram_count() > 0) {
-    // Avoid cloning types, compile units, and (other) subprograms.
-    for (DISubprogram *ISP : DIFinder.subprograms()) {
-      if (ISP != SPClonedWithinModule)
-        MD.insert(ISP);
-    }
+  // Avoid cloning types, compile units, and (other) subprograms.
+  for (DISubprogram *ISP : DIFinder.subprograms())
+    if (ISP != SPClonedWithinModule)
+      MD.insert(ISP);
 
-    // If a subprogram isn't going to be cloned skip its lexical blocks as well.
-    for (DIScope *S : DIFinder.scopes()) {
-      auto *LScope = dyn_cast<DILocalScope>(S);
-      if (LScope && LScope->getSubprogram() != SPClonedWithinModule)
-        MD.insert(S);
-    }
+  // If a subprogram isn't going to be cloned skip its lexical blocks as well.
+  for (DIScope *S : DIFinder.scopes()) {
+    auto *LScope = dyn_cast<DILocalScope>(S);
+    if (LScope && LScope->getSubprogram() != SPClonedWithinModule)
+      MD.insert(S);
+  }
 
     for (DICompileUnit *CU : DIFinder.compile_units())
       MD.insert(CU);
 
     for (DIType *Type : DIFinder.types())
       MD.insert(Type);
-  } else {
-    assert(!SPClonedWithinModule &&
-           "Subprogram should be in DIFinder->subprogram_count()...");
-  }
 
   return MD;
 }

>From 33b79c9d3b7432b693810656a8eec5a17b99c396 Mon Sep 17 00:00:00 2001
From: Artem Pianykh <arr at fb.com>
Date: Tue, 25 Feb 2025 10:03:41 -0800
Subject: [PATCH 3/3] [NFC][Cloning] Add a helper to collect debug info from
 instructions

Summary:
Just moving around. This helper will be used for further refactoring.

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

stack-info: PR: https://github.com/llvm/llvm-project/pull/129145, branch: users/artempyanykh/fast-coro-upstream-part2-take2/3
---
 llvm/lib/Transforms/Utils/CloneFunction.cpp | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/llvm/lib/Transforms/Utils/CloneFunction.cpp b/llvm/lib/Transforms/Utils/CloneFunction.cpp
index 7a309f7390c77..e03c5c27b5ac1 100644
--- a/llvm/lib/Transforms/Utils/CloneFunction.cpp
+++ b/llvm/lib/Transforms/Utils/CloneFunction.cpp
@@ -40,6 +40,18 @@ using namespace llvm;
 
 #define DEBUG_TYPE "clone-function"
 
+namespace {
+void collectDebugInfoFromInstructions(const Function &F,
+                                      DebugInfoFinder &DIFinder) {
+  const Module *M = F.getParent();
+  if (M) {
+    // Inspect instructions to process e.g. DILexicalBlocks of inlined functions
+    for (const auto &I : instructions(F))
+      DIFinder.processInstruction(*M, I);
+  }
+}
+} // namespace
+
 /// See comments in Cloning.h.
 BasicBlock *llvm::CloneBasicBlock(const BasicBlock *BB, ValueToValueMapTy &VMap,
                                   const Twine &NameSuffix, Function *F,
@@ -146,12 +158,7 @@ DISubprogram *llvm::CollectDebugInfoForCloning(const Function &F,
   if (SPClonedWithinModule)
     DIFinder.processSubprogram(SPClonedWithinModule);
 
-  const Module *M = F.getParent();
-  if (M) {
-    // Inspect instructions to process e.g. DILexicalBlocks of inlined functions
-    for (const auto &I : instructions(F))
-      DIFinder.processInstruction(*M, I);
-  }
+  collectDebugInfoFromInstructions(F, DIFinder);
 
   return SPClonedWithinModule;
 }