[MC] Report fatal error for DWARF types for non-ELF object files

[JDevlieghere]

Summary

Getting the DWARF types section is only implemented for ELF object
files. We already disabled emitting debug types in clang (r337717), but
now we also report an fatal error (rather than crashing) when trying to
obtain this section in MC.

See PR38190 for more information.

[dblaikie]

Should the command line argument be ignored on platforms that don't support type units? (& this code should be an assert, rather than a runtime_fatal_error?)

llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
   UseRangesSection = !NoDwarfRangesSection && !TT.isNVPTX();
 
   // Use sections as references. Force for NVPTX.
   if (DwarfSectionsAsReferences == Default)
     UseSectionsAsReferences = TT.isNVPTX();
   else
     UseSectionsAsReferences = DwarfSectionsAsReferences == Enable;
 
-  GenerateTypeUnits = GenerateDwarfTypeUnits;
+  // Don't generate type units for unsupported object file formats.
+  GenerateTypeUnits =
+      A->TM.getTargetTriple().isOSBinFormatELF() && GenerateDwarfTypeUnits;
 
   TheAccelTableKind = computeAccelTableKind(
       DwarfVersion, GenerateTypeUnits, DebuggerTuning, A->TM.getTargetTriple());
 
   // Work around a GDB bug. GDB doesn't support the standard opcode;
   // SCE doesn't support GNU's; LLDB prefers the standard opcode, which
   // is defined as of DWARF 3.
   // See GDB bug 11616 - DW_OP_form_tls_address is unimplemented

llvm/trunk/lib/MC/MCObjectFileInfo.cpp

case Triple::Wasm:
     break;
   case Triple::UnknownObjectFormat:
     report_fatal_error("Cannot initialize MC for unknown object file format.");
     break;
   }
 }
 
 MCSection *MCObjectFileInfo::getDwarfTypesSection(uint64_t Hash) const {
+  switch (TT.getObjectFormat()) {
+  case Triple::ELF:
     return Ctx->getELFSection(".debug_types", ELF::SHT_PROGBITS, ELF::SHF_GROUP,
                               0, utostr(Hash));
+  case Triple::MachO:
+  case Triple::COFF:
+  case Triple::Wasm:
+  case Triple::UnknownObjectFormat:
+    report_fatal_error("Cannot get DWARF types section for this object file "
+                       "format: not implemented.");
+    break;
+  }
 }
 
 MCSection *
 MCObjectFileInfo::getStackSizesSection(const MCSection &TextSec) const {
   if (Env != IsELF)
     return StackSizesSection;
 
   const MCSectionELF &ElfSec = static_cast<const MCSectionELF &>(TextSec);

llvm/trunk/test/DebugInfo/X86/accel-tables-dwarf5.ll

 ; RUN: llc -mtriple=x86_64-pc-linux -filetype=obj -debugger-tune=lldb < %s \
 ; RUN:   | llvm-readobj -sections - | FileCheck --check-prefix=DEBUG_NAMES %s
 
 ; But not if also type units are enabled.
 ; TODO: This is the case because we currently don't generate DWARF v5-compatible
 ; type units. Change this once DWARF v5 type units are implemented.
 ; RUN: llc -mtriple=x86_64-pc-linux -filetype=obj -generate-type-units -debugger-tune=lldb < %s \
 ; RUN:   | llvm-readobj -sections - | FileCheck --check-prefix=NONE %s
+
+; Debug types are ignored for non-ELF targets which means it shouldn't affect
+; accelerator table generation.
 ; RUN: llc -mtriple=x86_64-apple-darwin12 -generate-type-units -filetype=obj < %s \
-; RUN:   | llvm-readobj -sections - | FileCheck --check-prefix=NONE %s
+; RUN:   | llvm-readobj -sections - | FileCheck --check-prefix=DEBUG_NAMES %s
 
 ; NONE-NOT: apple_names
 ; NONE-NOT: debug_names
 
 ; DEBUG_NAMES-NOT: apple_names
 ; DEBUG_NAMES: debug_names
 ; DEBUG_NAMES-NOT: apple_names
 

llvm/trunk/test/DebugInfo/X86/accel-tables.ll

 ; Verify the emission of accelerator tables for various targets for the DWARF<=4 case
 
 ; Darwin has the apple tables unless we specifically tune for gdb
 ; RUN: llc -mtriple=x86_64-apple-darwin12 -filetype=obj < %s \
 ; RUN:   | llvm-readobj -sections - | FileCheck --check-prefix=APPLE %s
 ; RUN: llc -mtriple=x86_64-apple-darwin12 -filetype=obj -debugger-tune=gdb < %s \
 ; RUN:   | llvm-readobj -sections - | FileCheck --check-prefix=NONE %s
 
 ; Linux does has debug_names tables only if we explicitly tune for lldb
 ; RUN: llc -mtriple=x86_64-pc-linux -filetype=obj < %s \
 ; RUN:   | llvm-readobj -sections - | FileCheck --check-prefix=NONE %s
 ; RUN: llc -mtriple=x86_64-pc-linux -filetype=obj -debugger-tune=lldb < %s \
 ; RUN:   | llvm-readobj -sections - | FileCheck --check-prefix=DEBUG_NAMES %s
 
-; Neither target has accelerator tables if type units are enabled, as DWARF v4
-; type units are not compatible with accelerator tables.
+; No accelerator tables if type units are enabled, as DWARF v4 type units are
+; not compatible with accelerator tables.
 ; RUN: llc -mtriple=x86_64-pc-linux -filetype=obj -generate-type-units -debugger-tune=lldb < %s \
 ; RUN:   | llvm-readobj -sections - | FileCheck --check-prefix=NONE %s
+
+; Debug types are ignored for non-ELF targets which means it shouldn't affect
+; accelerator table generation.
 ; RUN: llc -mtriple=x86_64-apple-darwin12 -generate-type-units -filetype=obj < %s \
-; RUN:   | llvm-readobj -sections - | FileCheck --check-prefix=NONE %s
+; RUN:   | llvm-readobj -sections - | FileCheck --check-prefix=APPLE %s
 
 ; APPLE-NOT: debug_names
 ; APPLE: apple_names
 ; APPLE-NOT: debug_names
 
 ; NONE-NOT: apple_names
 ; NONE-NOT: debug_names