yonghong-song
diff --git a/‎llvm/include/llvm/Transforms/Utils/EmitChangedFuncDebugInfo.h‎
Lines changed: 33 additions & 0 deletions b/‎llvm/include/llvm/Transforms/Utils/EmitChangedFuncDebugInfo.h‎
Lines changed: 33 additions & 0 deletions
diff --git a/‎llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp‎
Lines changed: 66 additions & 0 deletions b/‎llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp‎
Lines changed: 66 additions & 0 deletions
diff --git a/‎llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h‎
Lines changed: 2 additions & 0 deletions b/‎llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h‎
Lines changed: 2 additions & 0 deletions
diff --git a/‎llvm/lib/Passes/PassBuilder.cpp‎
Lines changed: 1 addition & 0 deletions b/‎llvm/lib/Passes/PassBuilder.cpp‎
Lines changed: 1 addition & 0 deletions
diff --git a/‎llvm/lib/Passes/PassBuilderPipelines.cpp‎
Lines changed: 6 additions & 2 deletions b/‎llvm/lib/Passes/PassBuilderPipelines.cpp‎
Lines changed: 6 additions & 2 deletions
diff --git a/‎llvm/lib/Passes/PassRegistry.def‎
Lines changed: 1 addition & 0 deletions b/‎llvm/lib/Passes/PassRegistry.def‎
Lines changed: 1 addition & 0 deletions
diff --git a/‎llvm/lib/Transforms/Utils/CMakeLists.txt‎
Lines changed: 1 addition & 0 deletions b/‎llvm/lib/Transforms/Utils/CMakeLists.txt‎
Lines changed: 1 addition & 0 deletions
@@ -0,0 +1,33 @@
+//===- EmitChangedFuncDebugInfo.h - Emit Additional Debug Info -*- C++ --*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file
+/// Emit debug info for changed or new funcs.
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_UTILS_EMITCHANGEDFUNCDEBUGINFO_H
+#define LLVM_TRANSFORMS_UTILS_EMITCHANGEDFUNCDEBUGINFO_H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+class Module;
+
+// Pass that emits late dwarf.
+class EmitChangedFuncDebugInfoPass
+    : public PassInfoMixin<EmitChangedFuncDebugInfoPass> {
+public:
+  EmitChangedFuncDebugInfoPass() = default;
+
+  PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
+};
+
+} // end namespace llvm
+
+#endif // LLVM_TRANSFORMS_UTILS_EMITCHANGEDFUNCDEBUGINFO_H
@@ -1280,11 +1280,77 @@ void DwarfDebug::finishSubprogramDefinitions() {
   }
 }
 
+void DwarfDebug::addChangedSubprograms() {
+  // Generate additional dwarf for functions with signature changed.
+  DICompileUnit *ExtraCU = nullptr;
+  for (DICompileUnit *CUNode : MMI->getModule()->debug_compile_units()) {
+    if (CUNode->getFile()->getFilename() == "<changed_signatures>") {
+      ExtraCU = CUNode;
+      break;
+    }
+  }
+  if (!ExtraCU)
+    return;
+
+  llvm::DebugInfoFinder DIF;
+  DIF.processModule(*MMI->getModule());
+  for (auto *ExtraSP : DIF.subprograms()) {
+    if (ExtraSP->getUnit() != ExtraCU)
+      continue;
+
+    DISubprogram *SP = cast<DISubprogram>(ExtraSP->getScope());
+    DwarfCompileUnit &Cu = getOrCreateDwarfCompileUnit(SP->getUnit());
+    DIE *ScopeDIE =
+        DIE::get(DIEValueAllocator, dwarf::DW_TAG_inlined_subroutine);
+    Cu.getUnitDie().addChild(ScopeDIE);
+
+    Cu.addString(*ScopeDIE, dwarf::DW_AT_name, ExtraSP->getName());
+    if (!ExtraSP->getLinkageName().empty())
+      Cu.addString(*ScopeDIE, dwarf::DW_AT_linkage_name,
+                   ExtraSP->getLinkageName());
+
+    DITypeRefArray Args = ExtraSP->getType()->getTypeArray();
+
+    if (Args[0])
+      Cu.addType(*ScopeDIE, Args[0]);
+
+    if (ExtraSP->getType()->getCC() == llvm::dwarf::DW_CC_nocall) {
+      Cu.addUInt(*ScopeDIE, dwarf::DW_AT_calling_convention,
+                 dwarf::DW_FORM_data1, llvm::dwarf::DW_CC_nocall);
+    }
+
+    Cu.addFlag(*ScopeDIE, dwarf::DW_AT_artificial);
+
+    // dereference the DIE* for DIEEntry
+    DIE *OriginDIE = Cu.getOrCreateSubprogramDIE(SP, nullptr);
+    Cu.addDIEEntry(*ScopeDIE, dwarf::DW_AT_specification, DIEEntry(*OriginDIE));
+
+    SmallVector<const DILocalVariable *> ArgVars(Args.size());
+    for (const DINode *DN : ExtraSP->getRetainedNodes()) {
+      if (const auto *DV = dyn_cast<DILocalVariable>(DN)) {
+        uint32_t Arg = DV->getArg();
+        if (Arg)
+          ArgVars[Arg - 1] = DV;
+      }
+    }
+
+    for (unsigned i = 1, N = Args.size(); i < N; ++i) {
+      const DIType *Ty = Args[i];
+      DIE &Arg = Cu.createAndAddDIE(dwarf::DW_TAG_formal_parameter, *ScopeDIE);
+      const DILocalVariable *DV = ArgVars[i - 1];
+      Cu.addString(Arg, dwarf::DW_AT_name, DV->getName());
+      Cu.addType(Arg, Ty);
+    }
+  }
+}
+
 void DwarfDebug::finalizeModuleInfo() {
   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
 
   finishSubprogramDefinitions();
 
+  addChangedSubprograms();
+
   finishEntityDefinitions();
 
   bool HasEmittedSplitCU = false;
 
@@ -565,6 +565,8 @@ class DwarfDebug : public DebugHandlerBase {
 
   void finishSubprogramDefinitions();
 
+  void addChangedSubprograms();
+
   /// Finish off debug information after all functions have been
   /// processed.
   void finalizeModuleInfo();
 
@@ -351,6 +351,7 @@
 #include "llvm/Transforms/Utils/DXILUpgrade.h"
 #include "llvm/Transforms/Utils/Debugify.h"
 #include "llvm/Transforms/Utils/DeclareRuntimeLibcalls.h"
+#include "llvm/Transforms/Utils/EmitChangedFuncDebugInfo.h"
 #include "llvm/Transforms/Utils/EntryExitInstrumenter.h"
 #include "llvm/Transforms/Utils/FixIrreducible.h"
 #include "llvm/Transforms/Utils/HelloWorld.h"
 
@@ -135,6 +135,7 @@
 #include "llvm/Transforms/Utils/AssumeBundleBuilder.h"
 #include "llvm/Transforms/Utils/CanonicalizeAliases.h"
 #include "llvm/Transforms/Utils/CountVisits.h"
+#include "llvm/Transforms/Utils/EmitChangedFuncDebugInfo.h"
 #include "llvm/Transforms/Utils/EntryExitInstrumenter.h"
 #include "llvm/Transforms/Utils/ExtraPassManager.h"
 #include "llvm/Transforms/Utils/InjectTLIMappings.h"
@@ -1645,9 +1646,12 @@ PassBuilder::buildModuleOptimizationPipeline(OptimizationLevel Level,
   if (PTO.CallGraphProfile && !LTOPreLink)
     MPM.addPass(CGProfilePass(isLTOPostLink(LTOPhase)));
 
-  // RelLookupTableConverterPass runs later in LTO post-link pipeline.
-  if (!LTOPreLink)
+  // RelLookupTableConverterPass and EmitChangedFuncDebugInfoPass run later in
+  // LTO post-link pipeline.
+  if (!LTOPreLink) {
     MPM.addPass(RelLookupTableConverterPass());
+    MPM.addPass(EmitChangedFuncDebugInfoPass());
+  }
 
   return MPM;
 }
 
@@ -76,6 +76,7 @@ MODULE_PASS("dfsan", DataFlowSanitizerPass())
 MODULE_PASS("dot-callgraph", CallGraphDOTPrinterPass())
 MODULE_PASS("dxil-upgrade", DXILUpgradePass())
 MODULE_PASS("elim-avail-extern", EliminateAvailableExternallyPass())
+MODULE_PASS("emit-changed-func-debuginfo", EmitChangedFuncDebugInfoPass())
 MODULE_PASS("extract-blocks", BlockExtractorPass({}, false))
 MODULE_PASS("expand-variadics",
             ExpandVariadicsPass(ExpandVariadicsMode::Disable))
 
@@ -23,6 +23,7 @@ add_llvm_component_library(LLVMTransformUtils
   DebugSSAUpdater.cpp
   DeclareRuntimeLibcalls.cpp
   DemoteRegToStack.cpp
+  EmitChangedFuncDebugInfo.cpp
   DXILUpgrade.cpp
   EntryExitInstrumenter.cpp
   EscapeEnumerator.cpp