[RemoveDIs] Load into new debug info format by default in LLVM (#89799)

This patch enables parsing and creating modules directly into the new
debug info format. Prior to this patch, all modules were constructed
with the old debug info format by default, and would be converted into
the new format just before running LLVM passes. This is an important
milestone, in that this means that every tool will now be exposed to
debug records, rather than those that run LLVM passes. As far as I've
tested, all LLVM tools/projects now either handle debug records, or
convert them to the old intrinsic format.

There are a few unit tests that need updating for this patch; these are
either cases of tests that previously needed to set the debug info
format to function, or tests that depend on the old debug info format in
some way. There should be no visible change in the output of any LLVM
tool as a result of this patch, although the likelihood of this patch
breaking downstream code means an NFC tag might be a little misleading,
if not technically incorrect:

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

llvm/docs/ReleaseNotes.rst

@@ -170,6 +170,13 @@ 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/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);
 

llvm/unittests/IR/BasicBlockDbgInfoTest.cpp

@@ -72,8 +72,6 @@ TEST(BasicBlockDbgInfoTest, InsertAfterSelf) {
     !11 = !DILocation(line: 1, column: 1, scope: !6)
 )");
 
-  // Convert the module to "new" form debug-info.
-  M->convertToNewDbgValues();
   // Fetch the entry block.
   BasicBlock &BB = M->getFunction("f")->getEntryBlock();
 
@@ -104,8 +102,6 @@ TEST(BasicBlockDbgInfoTest, InsertAfterSelf) {
   auto Range2 = RetInst->getDbgRecordRange();
   EXPECT_EQ(std::distance(Range2.begin(), Range2.end()), 1u);
 
-  M->convertFromNewDbgValues();
-
   UseNewDbgInfoFormat = false;
 }
 
@@ -196,8 +192,6 @@ TEST(BasicBlockDbgInfoTest, MarkerOperations) {
 
   // Fetch the entry block,
   BasicBlock &BB = M->getFunction("f")->getEntryBlock();
-  // Convert the module to "new" form debug-info.
-  M->convertToNewDbgValues();
   EXPECT_EQ(BB.size(), 2u);
 
   // Fetch out our two markers,
@@ -332,8 +326,6 @@ TEST(BasicBlockDbgInfoTest, HeadBitOperations) {
   // Test that the movement of debug-data when using moveBefore etc and
   // insertBefore etc are governed by the "head" bit of iterators.
   BasicBlock &BB = M->getFunction("f")->getEntryBlock();
-  // Convert the module to "new" form debug-info.
-  M->convertToNewDbgValues();
 
   // Test that the head bit behaves as expected: it should be set when the
   // code wants the _start_ of the block, but not otherwise.
@@ -441,8 +433,6 @@ TEST(BasicBlockDbgInfoTest, InstrDbgAccess) {
   // Check that DbgVariableRecords can be accessed from Instructions without
   // digging into the depths of DbgMarkers.
   BasicBlock &BB = M->getFunction("f")->getEntryBlock();
-  // Convert the module to "new" form debug-info.
-  M->convertToNewDbgValues();
 
   Instruction *BInst = &*BB.begin();
   Instruction *CInst = BInst->getNextNode();
@@ -579,7 +569,6 @@ class DbgSpliceTest : public ::testing::Test {
   void SetUp() override {
     UseNewDbgInfoFormat = true;
     M = parseIR(C, SpliceTestIR.c_str());
-    M->convertToNewDbgValues();
 
     BBEntry = &M->getFunction("f")->getEntryBlock();
     BBExit = BBEntry->getNextNode();
@@ -1219,7 +1208,6 @@ TEST(BasicBlockDbgInfoTest, DbgSpliceTrailing) {
 
   BasicBlock &Entry = M->getFunction("f")->getEntryBlock();
   BasicBlock &Exit = *Entry.getNextNode();
-  M->convertToNewDbgValues();
 
   // Begin by forcing entry block to have dangling DbgVariableRecord.
   Entry.getTerminator()->eraseFromParent();
@@ -1273,7 +1261,6 @@ TEST(BasicBlockDbgInfoTest, RemoveInstAndReinsert) {
 )");
 
   BasicBlock &Entry = M->getFunction("f")->getEntryBlock();
-  M->convertToNewDbgValues();
 
   // Fetch the relevant instructions from the converted function.
   Instruction *SubInst = &*Entry.begin();
@@ -1352,7 +1339,6 @@ TEST(BasicBlockDbgInfoTest, RemoveInstAndReinsertForOneDbgVariableRecord) {
 )");
 
   BasicBlock &Entry = M->getFunction("f")->getEntryBlock();
-  M->convertToNewDbgValues();
 
   // Fetch the relevant instructions from the converted function.
   Instruction *SubInst = &*Entry.begin();
@@ -1436,7 +1422,6 @@ TEST(BasicBlockDbgInfoTest, DbgSpliceToEmpty1) {
   Function &F = *M->getFunction("f");
   BasicBlock &Entry = F.getEntryBlock();
   BasicBlock &Exit = *Entry.getNextNode();
-  M->convertToNewDbgValues();
 
   // Begin by forcing entry block to have dangling DbgVariableRecord.
   Entry.getTerminator()->eraseFromParent();
@@ -1506,7 +1491,6 @@ TEST(BasicBlockDbgInfoTest, DbgSpliceToEmpty2) {
   Function &F = *M->getFunction("f");
   BasicBlock &Entry = F.getEntryBlock();
   BasicBlock &Exit = *Entry.getNextNode();
-  M->convertToNewDbgValues();
 
   // Begin by forcing entry block to have dangling DbgVariableRecord.
   Entry.getTerminator()->eraseFromParent();
@@ -1576,7 +1560,6 @@ TEST(BasicBlockDbgInfoTest, DbgMoveToEnd) {
   Function &F = *M->getFunction("f");
   BasicBlock &Entry = F.getEntryBlock();
   BasicBlock &Exit = *Entry.getNextNode();
-  M->convertToNewDbgValues();
 
   // Move the return to the end of the entry block.
   Instruction *Br = Entry.getTerminator();