[NVPTX] Disable DWARF .file directory for PTX

Default behavior for .file directory was changed in D105856, but
ptxas (CUDA 11.5 release) refuses to parse it:

    $ llc -march=nvptx64 llvm/test/DebugInfo/NVPTX/debug-file-loc.ll
    $ ptxas debug-file-loc.s
    ptxas debug-file-loc.s, line 42; fatal   : Parsing error near
    '"foo.h"': syntax error

Added a new field to MCAsmInfo to control default value of
UseDwarfDirectory. This value is used if -dwarf-directory command line
option is not specified.

Differential Revision: https://reviews.llvm.org/D121299

clang/lib/CodeGen/BackendUtil.cpp

@@ -455,7 +455,10 @@ static bool initTargetOptions(DiagnosticsEngine &Diags,
   Options.MCOptions.SplitDwarfFile = CodeGenOpts.SplitDwarfFile;
   Options.MCOptions.MCRelaxAll = CodeGenOpts.RelaxAll;
   Options.MCOptions.MCSaveTempLabels = CodeGenOpts.SaveTempLabels;
-  Options.MCOptions.MCUseDwarfDirectory = !CodeGenOpts.NoDwarfDirectoryAsm;
+  Options.MCOptions.MCUseDwarfDirectory =
+      CodeGenOpts.NoDwarfDirectoryAsm
+          ? llvm::MCTargetOptions::DisableDwarfDirectory
+          : llvm::MCTargetOptions::EnableDwarfDirectory;
   Options.MCOptions.MCNoExecStack = CodeGenOpts.NoExecStack;
   Options.MCOptions.MCIncrementalLinkerCompatible =
       CodeGenOpts.IncrementalLinkerCompatible;

llvm/include/llvm/MC/MCAsmInfo.h

@@ -466,6 +466,10 @@ protected:
   /// the .loc/.file directives. Defaults to true.
   bool UsesDwarfFileAndLocDirectives = true;
 
+  /// True if DWARF `.file directory' directive syntax is used by
+  /// default.
+  bool EnableDwarfFileDirectoryDefault = true;
+
   /// True if the target needs the DWARF section length in the header (if any)
   /// of the DWARF section in the assembly file. Defaults to true.
   bool DwarfSectionSizeRequired = true;
@@ -808,6 +812,10 @@ public:
     return DwarfSectionSizeRequired;
   }
 
+  bool enableDwarfFileDirectoryDefault() const {
+    return EnableDwarfFileDirectoryDefault;
+  }
+
   void addInitialFrameState(const MCCFIInstruction &Inst);
 
   const std::vector<MCCFIInstruction> &getInitialFrameState() const {

llvm/include/llvm/MC/MCTargetOptions.h

@@ -47,7 +47,6 @@ public:
   bool MCNoDeprecatedWarn : 1;
   bool MCNoTypeCheck : 1;
   bool MCSaveTempLabels : 1;
-  bool MCUseDwarfDirectory : 1;
   bool MCIncrementalLinkerCompatible : 1;
   bool ShowMCEncoding : 1;
   bool ShowMCInst : 1;
@@ -59,6 +58,17 @@ public:
   bool Dwarf64 : 1;
   int DwarfVersion = 0;
 
+  enum DwarfDirectory {
+    // Force disable
+    DisableDwarfDirectory,
+    // Force enable, for assemblers that support
+    // `.file fileno directory filename' syntax
+    EnableDwarfDirectory,
+    // Default is based on the target
+    DefaultDwarfDirectory
+  };
+  DwarfDirectory MCUseDwarfDirectory;
+
   std::string ABIName;
   std::string AssemblyLanguage;
   std::string SplitDwarfFile;

llvm/lib/CodeGen/LLVMTargetMachine.cpp

@@ -165,13 +165,26 @@ Expected<std::unique_ptr<MCStreamer>> LLVMTargetMachine::createMCStreamer(
     if (Options.MCOptions.ShowMCEncoding)
       MCE.reset(getTarget().createMCCodeEmitter(MII, Context));
 
+    bool UseDwarfDirectory = false;
+    switch (Options.MCOptions.MCUseDwarfDirectory) {
+    case MCTargetOptions::DisableDwarfDirectory:
+      UseDwarfDirectory = false;
+      break;
+    case MCTargetOptions::EnableDwarfDirectory:
+      UseDwarfDirectory = true;
+      break;
+    case MCTargetOptions::DefaultDwarfDirectory:
+      UseDwarfDirectory = MAI.enableDwarfFileDirectoryDefault();
+      break;
+    }
+
     std::unique_ptr<MCAsmBackend> MAB(
         getTarget().createMCAsmBackend(STI, MRI, Options.MCOptions));
     auto FOut = std::make_unique<formatted_raw_ostream>(Out);
     MCStreamer *S = getTarget().createAsmStreamer(
         Context, std::move(FOut), Options.MCOptions.AsmVerbose,
-        Options.MCOptions.MCUseDwarfDirectory, InstPrinter, std::move(MCE),
-        std::move(MAB), Options.MCOptions.ShowMCInst);
+        UseDwarfDirectory, InstPrinter, std::move(MCE), std::move(MAB),
+        Options.MCOptions.ShowMCInst);
     AsmStreamer.reset(S);
     break;
   }

llvm/lib/MC/MCTargetOptions.cpp

@@ -13,11 +13,11 @@ using namespace llvm;
 
 MCTargetOptions::MCTargetOptions()
     : MCRelaxAll(false), MCNoExecStack(false), MCFatalWarnings(false),
-      MCNoWarn(false), MCNoDeprecatedWarn(false),
-      MCNoTypeCheck(false), MCSaveTempLabels(false),
-      MCUseDwarfDirectory(false), MCIncrementalLinkerCompatible(false),
-      ShowMCEncoding(false), ShowMCInst(false), AsmVerbose(false),
-      PreserveAsmComments(true), Dwarf64(false) {}
+      MCNoWarn(false), MCNoDeprecatedWarn(false), MCNoTypeCheck(false),
+      MCSaveTempLabels(false), MCUseDwarfDirectory(DefaultDwarfDirectory),
+      MCIncrementalLinkerCompatible(false), ShowMCEncoding(false),
+      ShowMCInst(false), AsmVerbose(false), PreserveAsmComments(true),
+      Dwarf64(false) {}
 
 StringRef MCTargetOptions::getABIName() const {
   return ABIName;

llvm/lib/Target/NVPTX/MCTargetDesc/NVPTXMCAsmInfo.cpp

@@ -58,4 +58,8 @@ NVPTXMCAsmInfo::NVPTXMCAsmInfo(const Triple &TheTriple,
   // Avoid using parens for identifiers starting with $ - ptxas does
   // not expect them.
   UseParensForDollarSignNames = false;
+
+  // ptxas does not support DWARF `.file fileno directory filename'
+  // syntax as of v11.X.
+  EnableDwarfFileDirectoryDefault = false;
 }

llvm/test/DebugInfo/NVPTX/dbg-declare-alloca.ll

@@ -1,4 +1,4 @@
-; RUN: llc < %s -mtriple=nvptx64-nvidia-cuda -dwarf-directory=0 | FileCheck %s
+; RUN: llc < %s -mtriple=nvptx64-nvidia-cuda | FileCheck %s
 
 ; CHECK: .target sm_20, debug
 

llvm/test/DebugInfo/NVPTX/debug-file-loc-only.ll

@@ -27,8 +27,8 @@ bb:
   ret void, !dbg !11
 }
 
-; CHECK-DAG: .file [[FOO]] "{{.*}}foo.h"
-; CHECK-DAG: .file [[BAR]] "{{.*}}bar.cu"
+; CHECK-DAG: .file [[FOO]] "/source/dir/foo.h"
+; CHECK-DAG: .file [[BAR]] "/source/dir/bar.cu"
 
 ; CHECK-NOT: .section .debug{{.*}}
 

llvm/test/DebugInfo/NVPTX/debug-file-loc.ll

@@ -27,8 +27,8 @@ bb:
   ret void, !dbg !11
 }
 
-; CHECK-DAG: .file [[FOO]] "{{.*}}foo.h"
-; CHECK-DAG: .file [[BAR]] "{{.*}}bar.cu"
+; CHECK-DAG: .file [[FOO]] "/source/dir/foo.h"
+; CHECK-DAG: .file [[BAR]] "/source/dir/bar.cu"
 ; CHECK: .section .debug_abbrev
 ; CHECK-NEXT: {
 ; CHECK-NEXT: .b8 1                                // Abbreviation Code

llvm/test/DebugInfo/NVPTX/debug-loc-offset.ll

@@ -1,4 +1,4 @@
-; RUN: llc -mtriple=nvptx64-nvidia-cuda -dwarf-directory=0 < %s | FileCheck %s
+; RUN: llc -mtriple=nvptx64-nvidia-cuda < %s | FileCheck %s
 
 ; CHECK: .target sm_{{[0-9]+}}, debug
 

llvm/test/DebugInfo/NVPTX/dwarf-file-dir.ll

@@ -0,0 +1,27 @@
+; RUN: llc < %s -mtriple=nvptx64-nvidia-cuda | FileCheck --check-prefix=CHECK-NODIR %s
+; RUN: llc < %s -mtriple=nvptx64-nvidia-cuda -dwarf-directory=1 | FileCheck --check-prefix=CHECK-DIR %s
+
+; CHECK-NODIR: .file   {{[0-9]+}} "/tmp/dbginfo/a/a.cpp"
+;
+; ptxas does not support .file directory syntax, but it can still be
+; forced by -dwarf-directory=1
+; CHECK-DIR:   .file   {{[0-9]+}} "/tmp/dbginfo/a" "a.cpp"
+
+define void @_Z4funcv() !dbg !4 {
+entry:
+  ret void, !dbg !5
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!8, !9}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.5.0 ", isOptimized: false, emissionKind: FullDebug, file: !1, enums: !2, retainedTypes: !2, globals: !2, imports: !2)
+!1 = !DIFile(filename: "a.cpp", directory: "/tmp/dbginfo/a")
+!2 = !{}
+!4 = distinct !DISubprogram(name: "func", linkageName: "_Z4funcv", line: 1, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 1, file: !1, scope: !1, type: !6, retainedNodes: !2)
+!5 = !DILocation(line: 2, scope: !4)
+!6 = !DISubroutineType(types: !7)
+!7 = !{null}
+!8 = !{i32 2, !"Dwarf Version", i32 4}
+!9 = !{i32 1, !"Debug Info Version", i32 3}
+

llvm/tools/llc/llc.cpp

@@ -503,11 +503,22 @@ static int compileModule(char **argv, LLVMContext &Context) {
         TargetMachine::parseBinutilsVersion(BinutilsVersion);
     Options.DisableIntegratedAS = NoIntegratedAssembler;
     Options.MCOptions.ShowMCEncoding = ShowMCEncoding;
-    Options.MCOptions.MCUseDwarfDirectory = DwarfDirectory;
     Options.MCOptions.AsmVerbose = AsmVerbose;
     Options.MCOptions.PreserveAsmComments = PreserveComments;
     Options.MCOptions.IASSearchPaths = IncludeDirs;
     Options.MCOptions.SplitDwarfFile = SplitDwarfFile;
+    if (DwarfDirectory.getPosition()) {
+      Options.MCOptions.MCUseDwarfDirectory =
+          DwarfDirectory ? MCTargetOptions::EnableDwarfDirectory
+                         : MCTargetOptions::DisableDwarfDirectory;
+    } else {
+      // -dwarf-directory is not set explicitly. Some assemblers
+      // (e.g. GNU as or ptxas) do not support `.file directory'
+      // syntax prior to DWARFv5. Let the target decide the default
+      // value.
+      Options.MCOptions.MCUseDwarfDirectory =
+          MCTargetOptions::DefaultDwarfDirectory;
+    }
   };
 
   Optional<Reloc::Model> RM = codegen::getExplicitRelocModel();