Repply#2 "[RemoveDIs] Load into new debug info format by default in L…

…LVM (#89799)"

Reapplies the original commit:
  2f01fd9

The previous application of this patch failed due to some missing
DbgVariableRecord support in clang, which has been added now by commit
8805465.

This will probably break some downstream tools that don't already handle
debug records. If your downstream code breaks as a result of this
change, the simplest fix is to convert the module in question to the old
debug format before you process it, using
`Module::convertFromNewDbgValues()`. For more information about how to
handle debug records or about what has changed, see the migration
document:
    https://llvm.org/docs/RemoveDIsDebugInfo.html

This reverts commit 4fd319a.

llvm/docs/ReleaseNotes.rst

@@ -173,6 +173,13 @@ Changes to the Metadata Info
 Changes to the Debug Info
 ---------------------------------
 
+* LLVM has switched from using debug intrinsics internally to using debug
+  records by default. This should happen transparently when using the DIBuilder
+  to construct debug variable information, but will require changes for any code
+  that interacts with debug intrinsics directly. Debug intrinsics will only be
+  supported on a best-effort basis from here onwards; for more information, see
+  the `migration docs <https://llvm.org/docs/RemoveDIsDebugInfo.html>`_.
+
 Changes to the LLVM tools
 ---------------------------------
 * llvm-nm and llvm-objdump can now print symbol information from linked

llvm/include/llvm/AsmParser/LLParser.h

@@ -337,7 +337,6 @@ namespace llvm {
 
     // Top-Level Entities
     bool parseTopLevelEntities();
-    bool finalizeDebugInfoFormat(Module *M);
     void dropUnknownMetadataReferences();
     bool validateEndOfModule(bool UpgradeDebugInfo);
     bool validateEndOfIndex();

llvm/lib/AsmParser/LLParser.cpp

@@ -74,23 +74,6 @@ static std::string getTypeString(Type *T) {
   return Tmp.str();
 }
 
-// Whatever debug info format we parsed, we should convert to the expected debug
-// info format immediately afterwards.
-bool LLParser::finalizeDebugInfoFormat(Module *M) {
-  // We should have already returned an error if we observed both intrinsics and
-  // records in this IR.
-  assert(!(SeenNewDbgInfoFormat && SeenOldDbgInfoFormat) &&
-         "Mixed debug intrinsics/records seen without a parsing error?");
-  if (PreserveInputDbgFormat == cl::boolOrDefault::BOU_TRUE) {
-    UseNewDbgInfoFormat = SeenNewDbgInfoFormat;
-    WriteNewDbgInfoFormatToBitcode = SeenNewDbgInfoFormat;
-    WriteNewDbgInfoFormat = SeenNewDbgInfoFormat;
-  } else if (M) {
-    M->setIsNewDbgInfoFormat(false);
-  }
-  return false;
-}
-
 /// Run: module ::= toplevelentity*
 bool LLParser::Run(bool UpgradeDebugInfo,
                    DataLayoutCallbackTy DataLayoutCallback) {
@@ -108,7 +91,7 @@ bool LLParser::Run(bool UpgradeDebugInfo,
   }
 
   return parseTopLevelEntities() || validateEndOfModule(UpgradeDebugInfo) ||
-         validateEndOfIndex() || finalizeDebugInfoFormat(M);
+         validateEndOfIndex();
 }
 
 bool LLParser::parseStandaloneConstantValue(Constant *&C,
@@ -207,6 +190,18 @@ void LLParser::dropUnknownMetadataReferences() {
 bool LLParser::validateEndOfModule(bool UpgradeDebugInfo) {
   if (!M)
     return false;
+
+  // We should have already returned an error if we observed both intrinsics and
+  // records in this IR.
+  assert(!(SeenNewDbgInfoFormat && SeenOldDbgInfoFormat) &&
+         "Mixed debug intrinsics/records seen without a parsing error?");
+  if (PreserveInputDbgFormat == cl::boolOrDefault::BOU_TRUE) {
+    UseNewDbgInfoFormat = SeenNewDbgInfoFormat;
+    WriteNewDbgInfoFormatToBitcode = SeenNewDbgInfoFormat;
+    WriteNewDbgInfoFormat = SeenNewDbgInfoFormat;
+    M->setNewDbgInfoFormatFlag(SeenNewDbgInfoFormat);
+  }
+
   // Handle any function attribute group forward references.
   for (const auto &RAG : ForwardRefAttrGroups) {
     Value *V = RAG.first;
@@ -439,6 +434,9 @@ bool LLParser::validateEndOfModule(bool UpgradeDebugInfo) {
   UpgradeModuleFlags(*M);
   UpgradeSectionAttributes(*M);
 
+  if (PreserveInputDbgFormat != cl::boolOrDefault::BOU_TRUE)
+    M->setIsNewDbgInfoFormat(UseNewDbgInfoFormat);
+
   if (!Slots)
     return false;
   // Initialize the slot mapping.

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -4319,7 +4319,7 @@ Error BitcodeReader::parseModule(uint64_t ResumeBit,
   if (PreserveInputDbgFormat != cl::boolOrDefault::BOU_TRUE) {
     TheModule->IsNewDbgInfoFormat =
         UseNewDbgInfoFormat &&
-        LoadBitcodeIntoNewDbgInfoFormat == cl::boolOrDefault::BOU_TRUE;
+        LoadBitcodeIntoNewDbgInfoFormat != cl::boolOrDefault::BOU_FALSE;
   }
 
   this->ValueTypeCallback = std::move(Callbacks.ValueType);

llvm/lib/IR/BasicBlock.cpp

@@ -181,7 +181,7 @@ template class llvm::SymbolTableListTraits<Instruction,
 BasicBlock::BasicBlock(LLVMContext &C, const Twine &Name, Function *NewParent,
                        BasicBlock *InsertBefore)
     : Value(Type::getLabelTy(C), Value::BasicBlockVal),
-      IsNewDbgInfoFormat(false), Parent(nullptr) {
+      IsNewDbgInfoFormat(UseNewDbgInfoFormat), Parent(nullptr) {
 
   if (NewParent)
     insertInto(NewParent, InsertBefore);

llvm/lib/IR/DebugProgramInstruction.cpp

@@ -366,8 +366,8 @@ void DbgVariableRecord::setKillLocation() {
 }
 
 bool DbgVariableRecord::isKillLocation() const {
-  return (getNumVariableLocationOps() == 0 &&
-          !getExpression()->isComplex()) ||
+  return (!hasArgList() && isa<MDNode>(getRawLocation())) ||
+         (getNumVariableLocationOps() == 0 && !getExpression()->isComplex()) ||
          any_of(location_ops(), [](Value *V) { return isa<UndefValue>(V); });
 }
 

llvm/lib/IR/Function.cpp

@@ -83,6 +83,8 @@ static cl::opt<unsigned> NonGlobalValueMaxNameSize(
     "non-global-value-max-name-size", cl::Hidden, cl::init(1024),
     cl::desc("Maximum size for the name of non-global values."));
 
+extern cl::opt<bool> UseNewDbgInfoFormat;
+
 void Function::convertToNewDbgValues() {
   IsNewDbgInfoFormat = true;
   for (auto &BB : *this) {
@@ -438,7 +440,7 @@ Function::Function(FunctionType *Ty, LinkageTypes Linkage, unsigned AddrSpace,
     : GlobalObject(Ty, Value::FunctionVal,
                    OperandTraits<Function>::op_begin(this), 0, Linkage, name,
                    computeAddrSpace(AddrSpace, ParentModule)),
-      NumArgs(Ty->getNumParams()), IsNewDbgInfoFormat(false) {
+      NumArgs(Ty->getNumParams()), IsNewDbgInfoFormat(UseNewDbgInfoFormat) {
   assert(FunctionType::isValidReturnType(getReturnType()) &&
          "invalid return type");
   setGlobalObjectSubClassData(0);

llvm/lib/IR/Module.cpp

@@ -54,6 +54,8 @@
 
 using namespace llvm;
 
+extern cl::opt<bool> UseNewDbgInfoFormat;
+
 //===----------------------------------------------------------------------===//
 // Methods to implement the globals and functions lists.
 //
@@ -72,7 +74,7 @@ template class llvm::SymbolTableListTraits<GlobalIFunc>;
 Module::Module(StringRef MID, LLVMContext &C)
     : Context(C), ValSymTab(std::make_unique<ValueSymbolTable>(-1)),
       ModuleID(std::string(MID)), SourceFileName(std::string(MID)), DL(""),
-      IsNewDbgInfoFormat(false) {
+      IsNewDbgInfoFormat(UseNewDbgInfoFormat) {
   Context.addModule(this);
 }
 

llvm/tools/llvm-as/llvm-as.cpp

@@ -142,11 +142,10 @@ int main(int argc, char **argv) {
   }
 
   // Convert to new debug format if requested.
-  assert(!M->IsNewDbgInfoFormat && "Unexpectedly in new debug mode");
-  if (UseNewDbgInfoFormat && WriteNewDbgInfoFormatToBitcode) {
-    M->convertToNewDbgValues();
+  M->setIsNewDbgInfoFormat(UseNewDbgInfoFormat &&
+                           WriteNewDbgInfoFormatToBitcode);
+  if (M->IsNewDbgInfoFormat)
     M->removeDebugIntrinsicDeclarations();
-  }
 
   std::unique_ptr<ModuleSummaryIndex> Index = std::move(ModuleAndIndex.Index);
 

llvm/tools/llvm-dis/llvm-dis.cpp

@@ -258,7 +258,7 @@ int main(int argc, char **argv) {
       // All that llvm-dis does is write the assembly to a file.
       if (!DontPrint) {
         if (M) {
-          ScopedDbgInfoFormatSetter FormatSetter(*M, WriteNewDbgInfoFormat);
+          M->setIsNewDbgInfoFormat(WriteNewDbgInfoFormat);
           if (WriteNewDbgInfoFormat)
             M->removeDebugIntrinsicDeclarations();
           M->print(Out->os(), Annotator.get(), PreserveAssemblyUseListOrder);

llvm/tools/llvm-link/llvm-link.cpp

@@ -489,12 +489,6 @@ int main(int argc, char **argv) {
   if (LoadBitcodeIntoNewDbgInfoFormat == cl::boolOrDefault::BOU_UNSET)
     LoadBitcodeIntoNewDbgInfoFormat = cl::boolOrDefault::BOU_TRUE;
 
-  // RemoveDIs debug-info transition: tests may request that we /try/ to use the
-  // new debug-info format.
-  if (TryUseNewDbgInfoFormat) {
-    // Turn the new debug-info format on.
-    UseNewDbgInfoFormat = true;
-  }
   // Since llvm-link collects multiple IR modules together, for simplicity's
   // sake we disable the "PreserveInputDbgFormat" flag to enforce a single
   // debug info format.
@@ -556,7 +550,7 @@ int main(int argc, char **argv) {
     SetFormat(WriteNewDbgInfoFormat);
     Composite->print(Out.os(), nullptr, PreserveAssemblyUseListOrder);
   } else if (Force || !CheckBitcodeOutputToConsole(Out.os())) {
-    SetFormat(WriteNewDbgInfoFormatToBitcode);
+    SetFormat(UseNewDbgInfoFormat && WriteNewDbgInfoFormatToBitcode);
     WriteBitcodeToFile(*Composite, Out.os(), PreserveBitcodeUseListOrder);
   }
 

llvm/unittests/Analysis/IRSimilarityIdentifierTest.cpp

@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Analysis/IRSimilarityIdentifier.h"
+#include "llvm/ADT/ScopeExit.h"
 #include "llvm/AsmParser/Parser.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
@@ -22,6 +23,27 @@
 using namespace llvm;
 using namespace IRSimilarity;
 
+extern llvm::cl::opt<bool> UseNewDbgInfoFormat;
+extern cl::opt<cl::boolOrDefault> PreserveInputDbgFormat;
+extern bool WriteNewDbgInfoFormatToBitcode;
+extern cl::opt<bool> WriteNewDbgInfoFormat;
+
+// Backup all of the existing settings that may be modified when
+// PreserveInputDbgFormat=true, so that when the test is finished we return them
+// (and the "preserve" setting) to their original values.
+static auto SaveDbgInfoFormat() {
+  return make_scope_exit(
+      [OldPreserveInputDbgFormat = PreserveInputDbgFormat.getValue(),
+       OldUseNewDbgInfoFormat = UseNewDbgInfoFormat.getValue(),
+       OldWriteNewDbgInfoFormatToBitcode = WriteNewDbgInfoFormatToBitcode,
+       OldWriteNewDbgInfoFormat = WriteNewDbgInfoFormat.getValue()] {
+        PreserveInputDbgFormat = OldPreserveInputDbgFormat;
+        UseNewDbgInfoFormat = OldUseNewDbgInfoFormat;
+        WriteNewDbgInfoFormatToBitcode = OldWriteNewDbgInfoFormatToBitcode;
+        WriteNewDbgInfoFormat = OldWriteNewDbgInfoFormat;
+      });
+}
+
 static std::unique_ptr<Module> makeLLVMModule(LLVMContext &Context,
                                               StringRef ModuleStr) {
   SMDiagnostic Err;
@@ -1308,6 +1330,9 @@ TEST(IRInstructionMapper, CallBrInstIllegal) {
 
 // Checks that an debuginfo intrinsics are mapped to be invisible.  Since they
 // do not semantically change the program, they can be recognized as similar.
+// FIXME: PreserveInputDbgFormat is set to true because this test contains
+// malformed debug info that cannot be converted to the new debug info format;
+// this test should be updated later to use valid debug info.
 TEST(IRInstructionMapper, DebugInfoInvisible) {
   StringRef ModuleString = R"(
                           define i32 @f(i32 %a, i32 %b) {
@@ -1320,6 +1345,8 @@ TEST(IRInstructionMapper, DebugInfoInvisible) {
 
                           declare void @llvm.dbg.value(metadata)
                           !0 = distinct !{!"test\00", i32 10})";
+  auto SettingGuard = SaveDbgInfoFormat();
+  PreserveInputDbgFormat = cl::boolOrDefault::BOU_TRUE;
   LLVMContext Context;
   std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleString);
 
@@ -1916,6 +1943,9 @@ TEST(IRSimilarityCandidate, CheckRegionsDifferentTypes) {
 
 // Check that debug instructions do not impact similarity. They are marked as
 // invisible.
+// FIXME: PreserveInputDbgFormat is set to true because this test contains
+// malformed debug info that cannot be converted to the new debug info format;
+// this test should be updated later to use valid debug info.
 TEST(IRSimilarityCandidate, IdenticalWithDebug) {
   StringRef ModuleString = R"(
                           define i32 @f(i32 %a, i32 %b) {
@@ -1938,6 +1968,8 @@ TEST(IRSimilarityCandidate, IdenticalWithDebug) {
                           declare void @llvm.dbg.value(metadata)
                           !0 = distinct !{!"test\00", i32 10}
                           !1 = distinct !{!"test\00", i32 11})";
+  auto SettingGuard = SaveDbgInfoFormat();
+  PreserveInputDbgFormat = cl::boolOrDefault::BOU_TRUE;
   LLVMContext Context;
   std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleString);