[llvm] [DebugInfo][RemoveDIs] Set new-dbg-info flag from Modules correctly (PR #82373)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-ir

Author: Jeremy Morse (jmorse)

<details>
<summary>Changes</summary>

It turns out there's a pathway for Functions to be inserted into modules without having the "New" debug-info flag set correctly, which this patch fixes. Sadly there isn't a Module::insert method to instrument out there, everyone touches the list directly.

This fix exposes a path where such functions are produced in the outliner in the wrong mode; requiring a fix there to correctly drop RemoveDIs-mode debug-info. This is covered by test/DebugInfo/AArch64/ir-outliner.ll

---
Full diff: https://github.com/llvm/llvm-project/pull/82373.diff


2 Files Affected:

- (modified) llvm/lib/IR/Function.cpp (+3-1) 
- (modified) llvm/lib/Transforms/IPO/IROutliner.cpp (+7-4) 


``````````diff
diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index fceffbc3cea6d7..056e4f31981a72 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -437,8 +437,10 @@ Function::Function(FunctionType *Ty, LinkageTypes Linkage, unsigned AddrSpace,
   if (Ty->getNumParams())
     setValueSubclassData(1);   // Set the "has lazy arguments" bit.
 
-  if (ParentModule)
+  if (ParentModule) {
     ParentModule->getFunctionList().push_back(this);
+    IsNewDbgInfoFormat = ParentModule->IsNewDbgInfoFormat;
+  }
 
   HasLLVMReservedName = getName().starts_with("llvm.");
   // Ensure intrinsics have the right parameter attributes.
diff --git a/llvm/lib/Transforms/IPO/IROutliner.cpp b/llvm/lib/Transforms/IPO/IROutliner.cpp
index 8e6d0e814372d6..48470bc71ff38a 100644
--- a/llvm/lib/Transforms/IPO/IROutliner.cpp
+++ b/llvm/lib/Transforms/IPO/IROutliner.cpp
@@ -721,6 +721,12 @@ static void moveFunctionData(Function &Old, Function &New,
     std::vector<Instruction *> DebugInsts;
 
     for (Instruction &Val : CurrBB) {
+      // Since debug-info originates from many different locations in the
+      // program, it will cause incorrect reporting from a debugger if we keep
+      // the same debug instructions. Drop non-intrinsic DPValues here,
+      // collect intrinsics for removal later.
+      Val.dropDbgValues();
+
       // We must handle the scoping of called functions differently than
       // other outlined instructions.
       if (!isa<CallInst>(&Val)) {
@@ -744,10 +750,7 @@ static void moveFunctionData(Function &Old, Function &New,
       // From this point we are only handling call instructions.
       CallInst *CI = cast<CallInst>(&Val);
 
-      // We add any debug statements here, to be removed after.  Since the
-      // instructions originate from many different locations in the program,
-      // it will cause incorrect reporting from a debugger if we keep the
-      // same debug instructions.
+      // Collect debug intrinsics for later removal.
       if (isa<DbgInfoIntrinsic>(CI)) {
         DebugInsts.push_back(&Val);
         continue;

``````````

</details>


https://github.com/llvm/llvm-project/pull/82373