Adding support for inlined_at debug directive in NVPTX backend

Author: laxmansole

llvm/include/llvm/CodeGen/AsmPrinter.h

@@ -277,6 +277,10 @@ class LLVM_ABI AsmPrinter : public MachineFunctionPass {
   AsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer,
              char &ID = AsmPrinter::ID);
 
+  /// Create the DwarfDebug handler. Targets can override this to provide
+  /// custom debug information handling.
+  virtual DwarfDebug *createDwarfDebug();
+
 public:
   ~AsmPrinter() override;
 

llvm/include/llvm/MC/MCStreamer.h

@@ -902,6 +902,14 @@ class LLVM_ABI MCStreamer {
                                      StringRef FileName,
                                      StringRef Comment = {});
 
+  /// This is same as emitDwarfLocDirective, except has capability to
+  /// add inlined_at information.
+  virtual void emitDwarfLocDirectiveWithInlinedAt(
+      unsigned FileNo, unsigned Line, unsigned Column, unsigned FileIA,
+      unsigned LineIA, unsigned ColumnIA, const MCSymbol *Sym, unsigned Flags,
+      unsigned Isa, unsigned Discriminator, StringRef FileName,
+      StringRef Comment = {}) {}
+
   /// This implements the '.loc_label Name' directive.
   virtual void emitDwarfLocLabelDirective(SMLoc Loc, StringRef Name);
 

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -470,6 +470,8 @@ const MCSection *AsmPrinter::getCurrentSection() const {
   return OutStreamer->getCurrentSectionOnly();
 }
 
+DwarfDebug *AsmPrinter::createDwarfDebug() { return new DwarfDebug(this); }
+
 void AsmPrinter::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.setPreservesAll();
   MachineFunctionPass::getAnalysisUsage(AU);
@@ -592,7 +594,7 @@ bool AsmPrinter::doInitialization(Module &M) {
       Handlers.push_back(std::make_unique<CodeViewDebug>(this));
     if (!EmitCodeView || M.getDwarfVersion()) {
       if (hasDebugInfo()) {
-        DD = new DwarfDebug(this);
+        DD = createDwarfDebug();
         Handlers.push_back(std::unique_ptr<DwarfDebug>(DD));
       }
     }

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -2204,13 +2204,27 @@ void DwarfDebug::beginInstruction(const MachineInstr *MI) {
       Flags |= DWARF2_FLAG_IS_STMT;
   }
 
-  RecordSourceLine(DL, Flags);
+  // Call the hook that allows targets to customize source line recording
+  recordSourceLineHook(*MI, DL, Flags);
 
   // If we're not at line 0, remember this location.
   if (DL.getLine())
     PrevInstLoc = DL;
 }
 
+// Default implementation of target-specific hook for custom source line
+// recording
+void DwarfDebug::recordSourceLineHook(const MachineInstr &MI,
+                                      const DebugLoc &DL, unsigned Flags) {
+  SmallString<128> LocationString;
+  if (Asm->OutStreamer->isVerboseAsm()) {
+    raw_svector_ostream OS(LocationString);
+    DL.print(OS);
+  }
+  recordSourceLine(DL.getLine(), DL.getCol(), DL.getScope(), Flags,
+                   LocationString);
+}
+
 // Returns the position where we should place prologue_end, potentially nullptr,
 // which means "no good place to put prologue_end". Returns true in the second
 // return value if there are no setup instructions in this function at all,
@@ -2705,6 +2719,9 @@ void DwarfDebug::beginFunctionImpl(const MachineFunction *MF) {
   Asm->OutStreamer->getContext().setDwarfCompileUnitID(
       getDwarfCompileUnitIDForLineTable(CU));
 
+  // Call target-specific hook for custom initialization
+  beginFunctionHook(*MF);
+
   // Record beginning of function.
   PrologEndLoc = emitInitialLocDirective(
       *MF, Asm->OutStreamer->getContext().getDwarfCompileUnitID());

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h

@@ -394,9 +394,6 @@ class DwarfDebug : public DebugHandlerBase {
   /// table for the same directory as DW_AT_comp_dir.
   StringRef CompilationDir;
 
-  /// Holder for the file specific debug information.
-  DwarfFile InfoHolder;
-
   /// Holders for the various debug information flags that we might need to
   /// have exposed. See accessor functions below for description.
 
@@ -532,10 +529,6 @@ class DwarfDebug : public DebugHandlerBase {
 
   MCDwarfDwoLineTable *getDwoLineTable(const DwarfCompileUnit &);
 
-  const SmallVectorImpl<std::unique_ptr<DwarfCompileUnit>> &getUnits() {
-    return InfoHolder.getUnits();
-  }
-
   using InlinedEntity = DbgValueHistoryMap::InlinedEntity;
 
   void ensureAbstractEntityIsCreatedIfScoped(DwarfCompileUnit &CU,
@@ -711,6 +704,8 @@ class DwarfDebug : public DebugHandlerBase {
   void computeKeyInstructions(const MachineFunction *MF);
 
 protected:
+  /// Holder for the file specific debug information.
+  DwarfFile InfoHolder;
   /// Gather pre-function debug information.
   void beginFunctionImpl(const MachineFunction *MF) override;
 
@@ -722,6 +717,18 @@ class DwarfDebug : public DebugHandlerBase {
 
   void skippedNonDebugFunction() override;
 
+  /// Target-specific hook for custom initialization,
+  /// default implementation is empty, only being used for NVPTX target
+  virtual void beginFunctionHook(const MachineFunction &MF) {}
+
+  /// Target-specific hook for custom source line recording
+  virtual void recordSourceLineHook(const MachineInstr &MI, const DebugLoc &DL,
+                                    unsigned Flags);
+
+  const SmallVectorImpl<std::unique_ptr<DwarfCompileUnit>> &getUnits() {
+    return InfoHolder.getUnits();
+  }
+
 public:
   //===--------------------------------------------------------------------===//
   // Main entry points.

llvm/lib/CodeGen/AsmPrinter/DwarfStringPool.cpp

@@ -96,9 +96,12 @@ void DwarfStringPool::emit(AsmPrinter &Asm, MCSection *StrSection,
     if (ShouldCreateSymbols)
       Asm.OutStreamer->emitLabel(Entry->getValue().Symbol);
 
+    // Emit a comment with the string offset and the string itself.
+    Asm.OutStreamer->AddComment(
+        "string offset=" + Twine(Entry->getValue().Offset) + " ; " +
+        StringRef(Entry->getKeyData(), Entry->getKeyLength()));
+
     // Emit the string itself with a terminating null byte.
-    Asm.OutStreamer->AddComment("string offset=" +
-                                Twine(Entry->getValue().Offset));
     Asm.OutStreamer->emitBytes(
         StringRef(Entry->getKeyData(), Entry->getKeyLength() + 1));
   }

llvm/lib/MC/MCAsmStreamer.cpp

@@ -70,6 +70,17 @@ class MCAsmStreamer final : public MCStreamer {
   void emitCFIStartProcImpl(MCDwarfFrameInfo &Frame) override;
   void emitCFIEndProcImpl(MCDwarfFrameInfo &Frame) override;
 
+  /// Helper to emit common .loc directive flags, isa, and discriminator
+  void emitDwarfLocDirectiveFlags(unsigned Flags, unsigned Isa,
+                                  unsigned Discriminator);
+
+  /// Helper to emit the common suffix of .loc directives (flags, comment, EOL,
+  /// parent call)
+  void emitDwarfLocDirectiveSuffix(unsigned FileNo, unsigned Line,
+                                   unsigned Column, unsigned Flags,
+                                   unsigned Isa, unsigned Discriminator,
+                                   StringRef FileName, StringRef Comment);
+
 public:
   MCAsmStreamer(MCContext &Context, std::unique_ptr<formatted_raw_ostream> os,
                 std::unique_ptr<MCInstPrinter> printer,
@@ -297,6 +308,14 @@ class MCAsmStreamer final : public MCStreamer {
                              StringRef Location = {}) override;
   void emitDwarfLocLabelDirective(SMLoc Loc, StringRef Name) override;
 
+  void emitDwarfLocDirectiveWithInlinedAt(unsigned FileNo, unsigned Line,
+                                          unsigned Column, unsigned FileIA,
+                                          unsigned LineIA, unsigned ColIA,
+                                          const MCSymbol *Sym, unsigned Flags,
+                                          unsigned Isa, unsigned Discriminator,
+                                          StringRef FileName,
+                                          StringRef Comment = {}) override;
+
   MCSymbol *getDwarfLineTableSymbol(unsigned CUID) override;
 
   bool emitCVFileDirective(unsigned FileNo, StringRef Filename,
@@ -1675,6 +1694,57 @@ void MCAsmStreamer::emitDwarfFile0Directive(
     emitRawText(OS1.str());
 }
 
+/// Helper to emit common .loc directive flags, isa, and discriminator
+void MCAsmStreamer::emitDwarfLocDirectiveFlags(unsigned Flags, unsigned Isa,
+                                               unsigned Discriminator) {
+  if (!MAI->supportsExtendedDwarfLocDirective())
+    return;
+
+  if (Flags & DWARF2_FLAG_BASIC_BLOCK)
+    OS << " basic_block";
+  if (Flags & DWARF2_FLAG_PROLOGUE_END)
+    OS << " prologue_end";
+  if (Flags & DWARF2_FLAG_EPILOGUE_BEGIN)
+    OS << " epilogue_begin";
+
+  const unsigned OldFlags = getContext().getCurrentDwarfLoc().getFlags();
+  if ((Flags & DWARF2_FLAG_IS_STMT) != (OldFlags & DWARF2_FLAG_IS_STMT)) {
+    OS << " is_stmt ";
+    OS << ((Flags & DWARF2_FLAG_IS_STMT) ? "1" : "0");
+  }
+
+  if (Isa)
+    OS << " isa " << Isa;
+  if (Discriminator)
+    OS << " discriminator " << Discriminator;
+}
+
+/// Helper to emit the common suffix of .loc directives
+void MCAsmStreamer::emitDwarfLocDirectiveSuffix(unsigned FileNo, unsigned Line,
+                                                unsigned Column, unsigned Flags,
+                                                unsigned Isa,
+                                                unsigned Discriminator,
+                                                StringRef FileName,
+                                                StringRef Comment) {
+  // Emit flags, isa, and discriminator
+  emitDwarfLocDirectiveFlags(Flags, Isa, Discriminator);
+
+  // Emit verbose comment if enabled
+  if (IsVerboseAsm) {
+    OS.PadToColumn(MAI->getCommentColumn());
+    OS << MAI->getCommentString() << ' ';
+    if (Comment.empty())
+      OS << FileName << ':' << Line << ':' << Column;
+    else
+      OS << Comment;
+  }
+
+  // Emit end of line and update parent state
+  EmitEOL();
+  MCStreamer::emitDwarfLocDirective(FileNo, Line, Column, Flags, Isa,
+                                    Discriminator, FileName, Comment);
+}
+
 void MCAsmStreamer::emitDwarfLocDirective(unsigned FileNo, unsigned Line,
                                           unsigned Column, unsigned Flags,
                                           unsigned Isa, unsigned Discriminator,
@@ -1691,42 +1761,29 @@ void MCAsmStreamer::emitDwarfLocDirective(unsigned FileNo, unsigned Line,
     return;
   }
 
+  // Emit the basic .loc directive
   OS << "\t.loc\t" << FileNo << " " << Line << " " << Column;
-  if (MAI->supportsExtendedDwarfLocDirective()) {
-    if (Flags & DWARF2_FLAG_BASIC_BLOCK)
-      OS << " basic_block";
-    if (Flags & DWARF2_FLAG_PROLOGUE_END)
-      OS << " prologue_end";
-    if (Flags & DWARF2_FLAG_EPILOGUE_BEGIN)
-      OS << " epilogue_begin";
-
-    unsigned OldFlags = getContext().getCurrentDwarfLoc().getFlags();
-    if ((Flags & DWARF2_FLAG_IS_STMT) != (OldFlags & DWARF2_FLAG_IS_STMT)) {
-      OS << " is_stmt ";
-
-      if (Flags & DWARF2_FLAG_IS_STMT)
-        OS << "1";
-      else
-        OS << "0";
-    }
 
-    if (Isa)
-      OS << " isa " << Isa;
-    if (Discriminator)
-      OS << " discriminator " << Discriminator;
-  }
+  // Emit common suffix (flags, comment, EOL, parent call)
+  emitDwarfLocDirectiveSuffix(FileNo, Line, Column, Flags, Isa, Discriminator,
+                              FileName, Comment);
+}
 
-  if (IsVerboseAsm) {
-    OS.PadToColumn(MAI->getCommentColumn());
-    OS << MAI->getCommentString() << ' ';
-    if (Comment.empty())
-      OS << FileName << ':' << Line << ':' << Column;
-    else
-      OS << Comment;
-  }
-  EmitEOL();
-  this->MCStreamer::emitDwarfLocDirective(FileNo, Line, Column, Flags, Isa,
-                                          Discriminator, FileName, Comment);
+/// This is same as emitDwarfLocDirective, except also emits inlined function
+/// and inlined callsite information.
+void MCAsmStreamer::emitDwarfLocDirectiveWithInlinedAt(
+    unsigned FileNo, unsigned Line, unsigned Column, unsigned FileIA,
+    unsigned LineIA, unsigned ColIA, const MCSymbol *Sym, unsigned Flags,
+    unsigned Isa, unsigned Discriminator, StringRef FileName,
+    StringRef Comment) {
+  // Emit the basic .loc directive with NVPTX-specific extensions
+  OS << "\t.loc\t" << FileNo << " " << Line << " " << Column;
+  OS << ", function_name " << *Sym;
+  OS << ", inlined_at " << FileIA << " " << LineIA << " " << ColIA;
+
+  // Emit common suffix (flags, comment, EOL, parent call)
+  emitDwarfLocDirectiveSuffix(FileNo, Line, Column, Flags, Isa, Discriminator,
+                              FileName, Comment);
 }
 
 void MCAsmStreamer::emitDwarfLocLabelDirective(SMLoc Loc, StringRef Name) {

llvm/lib/Target/NVPTX/CMakeLists.txt

@@ -18,6 +18,7 @@ set(NVPTXCodeGen_sources
   NVPTXAssignValidGlobalNames.cpp
   NVPTXAtomicLower.cpp
   NVPTXCtorDtorLowering.cpp
+  NVPTXDwarfDebug.cpp
   NVPTXForwardParams.cpp
   NVPTXFrameLowering.cpp
   NVPTXGenericToNVVM.cpp

llvm/lib/Target/NVPTX/NVPTXAsmPrinter.cpp

@@ -17,6 +17,7 @@
 #include "MCTargetDesc/NVPTXMCAsmInfo.h"
 #include "MCTargetDesc/NVPTXTargetStreamer.h"
 #include "NVPTX.h"
+#include "NVPTXDwarfDebug.h"
 #include "NVPTXMCExpr.h"
 #include "NVPTXMachineFunctionInfo.h"
 #include "NVPTXRegisterInfo.h"
@@ -676,6 +677,10 @@ void NVPTXAsmPrinter::emitStartOfAsmFile(Module &M) {
   OutStreamer->emitRawText(OS1.str());
 }
 
+DwarfDebug *NVPTXAsmPrinter::createDwarfDebug() {
+  return new NVPTXDwarfDebug(this);
+}
+
 bool NVPTXAsmPrinter::doInitialization(Module &M) {
   const NVPTXTargetMachine &NTM = static_cast<const NVPTXTargetMachine &>(TM);
   const NVPTXSubtarget &STI = *NTM.getSubtargetImpl();

llvm/lib/Target/NVPTX/NVPTXAsmPrinter.h

@@ -194,6 +194,9 @@ class LLVM_LIBRARY_VISIBILITY NVPTXAsmPrinter : public AsmPrinter {
   bool doInitialization(Module &M) override;
   bool doFinalization(Module &M) override;
 
+  // Create NVPTX-specific DwarfDebug handler
+  DwarfDebug *createDwarfDebug() override;
+
 private:
   bool GlobalsEmitted;