[MC] Set SHT_MIPS_DWARF section type for all .debug_* sections on MIPS

[atanasyan]

Summary

All MIPS .debug_* sections should be marked with ELF type SHT_MIPS_DWARF accordingly the specification [1]. Also the same section type is assigned to these sections by GNU tools.

[1] ftp.software.ibm.com/software/os390/czos/dwarf/mips_extensions.pdf

[sdardis]

This patch appears to be missing the declaration for SHT_MIPS_DWARF = 0x7000001e in include/llvm/Support/ELF.h.

One comment request inlined.

lib/MC/MCObjectFileInfo.cpp

508 ↗

(On Diff #87875)

This hunk could probably do with a comment noting that it is historical behaviour / an extension to DWARF-2 for MIPS to mark debug sections with SHT_MIPS_DWARF rather than the usual SHT_PROGBITS.

llvm/trunk/include/llvm/Support/ELF.h

enum : unsigned {
   SHT_ARM_DEBUGOVERLAY = 0x70000004U,
   SHT_ARM_OVERLAYSECTION = 0x70000005U,
   SHT_HEX_ORDERED = 0x70000000,   // Link editor is to sort the entries in
                                   // this section based on their sizes
   SHT_X86_64_UNWIND = 0x70000001, // Unwind information
 
   SHT_MIPS_REGINFO = 0x70000006,  // Register usage information
   SHT_MIPS_OPTIONS = 0x7000000d,  // General options
+  SHT_MIPS_DWARF = 0x7000001e,    // DWARF debugging section.
   SHT_MIPS_ABIFLAGS = 0x7000002a, // ABI information.
 
   SHT_HIPROC = 0x7fffffff, // Highest processor arch-specific type.
   SHT_LOUSER = 0x80000000, // Lowest type reserved for applications.
   SHT_HIUSER = 0xffffffff  // Highest type reserved for applications.
 };
 
 // Section flags.

llvm/trunk/lib/MC/MCObjectFileInfo.cpp

void MCObjectFileInfo::initELFMCObjectFileInfo(const Triple &T) {
   // runtime hit for C++ apps.  Either the contents of the LSDA need to be
   // adjusted or this should be a data section.
   LSDASection = Ctx->getELFSection(".gcc_except_table", ELF::SHT_PROGBITS,
                                    ELF::SHF_ALLOC);
 
   COFFDebugSymbolsSection = nullptr;
   COFFDebugTypesSection = nullptr;
 
+  unsigned DebugSecType = ELF::SHT_PROGBITS;
+
+  // MIPS .debug_* sections should have SHT_MIPS_DWARF section type
+  // to distinguish among sections contain DWARF and ECOFF debug formats.
+  // Sections with ECOFF debug format are obsoleted and marked by SHT_PROGBITS.
+  if (T.getArch() == Triple::mips || T.getArch() == Triple::mipsel ||
+      T.getArch() == Triple::mips64 || T.getArch() == Triple::mips64el)
+    DebugSecType = ELF::SHT_MIPS_DWARF;
+
   // Debug Info Sections.
   DwarfAbbrevSection =
-      Ctx->getELFSection(".debug_abbrev", ELF::SHT_PROGBITS, 0);
-  DwarfInfoSection = Ctx->getELFSection(".debug_info", ELF::SHT_PROGBITS, 0);
-  DwarfLineSection = Ctx->getELFSection(".debug_line", ELF::SHT_PROGBITS, 0);
-  DwarfFrameSection = Ctx->getELFSection(".debug_frame", ELF::SHT_PROGBITS, 0);
+      Ctx->getELFSection(".debug_abbrev", DebugSecType, 0);
+  DwarfInfoSection = Ctx->getELFSection(".debug_info", DebugSecType, 0);
+  DwarfLineSection = Ctx->getELFSection(".debug_line", DebugSecType, 0);
+  DwarfFrameSection = Ctx->getELFSection(".debug_frame", DebugSecType, 0);
   DwarfPubNamesSection =
-      Ctx->getELFSection(".debug_pubnames", ELF::SHT_PROGBITS, 0);
+      Ctx->getELFSection(".debug_pubnames", DebugSecType, 0);
   DwarfPubTypesSection =
-      Ctx->getELFSection(".debug_pubtypes", ELF::SHT_PROGBITS, 0);
+      Ctx->getELFSection(".debug_pubtypes", DebugSecType, 0);
   DwarfGnuPubNamesSection =
-      Ctx->getELFSection(".debug_gnu_pubnames", ELF::SHT_PROGBITS, 0);
+      Ctx->getELFSection(".debug_gnu_pubnames", DebugSecType, 0);
   DwarfGnuPubTypesSection =
-      Ctx->getELFSection(".debug_gnu_pubtypes", ELF::SHT_PROGBITS, 0);
+      Ctx->getELFSection(".debug_gnu_pubtypes", DebugSecType, 0);
   DwarfStrSection =
-      Ctx->getELFSection(".debug_str", ELF::SHT_PROGBITS,
+      Ctx->getELFSection(".debug_str", DebugSecType,
                          ELF::SHF_MERGE | ELF::SHF_STRINGS, 1, "");
-  DwarfLocSection = Ctx->getELFSection(".debug_loc", ELF::SHT_PROGBITS, 0);
+  DwarfLocSection = Ctx->getELFSection(".debug_loc", DebugSecType, 0);
   DwarfARangesSection =
-      Ctx->getELFSection(".debug_aranges", ELF::SHT_PROGBITS, 0);
+      Ctx->getELFSection(".debug_aranges", DebugSecType, 0);
   DwarfRangesSection =
-      Ctx->getELFSection(".debug_ranges", ELF::SHT_PROGBITS, 0);
+      Ctx->getELFSection(".debug_ranges", DebugSecType, 0);
   DwarfMacinfoSection =
-      Ctx->getELFSection(".debug_macinfo", ELF::SHT_PROGBITS, 0);
+      Ctx->getELFSection(".debug_macinfo", DebugSecType, 0);
 
   // DWARF5 Experimental Debug Info
 
   // Accelerator Tables
   DwarfAccelNamesSection =
       Ctx->getELFSection(".apple_names", ELF::SHT_PROGBITS, 0);
   DwarfAccelObjCSection =
       Ctx->getELFSection(".apple_objc", ELF::SHT_PROGBITS, 0);
   DwarfAccelNamespaceSection =
       Ctx->getELFSection(".apple_namespaces", ELF::SHT_PROGBITS, 0);
   DwarfAccelTypesSection =
       Ctx->getELFSection(".apple_types", ELF::SHT_PROGBITS, 0);
 
   // Fission Sections
   DwarfInfoDWOSection =
-      Ctx->getELFSection(".debug_info.dwo", ELF::SHT_PROGBITS, 0);
+      Ctx->getELFSection(".debug_info.dwo", DebugSecType, 0);
   DwarfTypesDWOSection =
-      Ctx->getELFSection(".debug_types.dwo", ELF::SHT_PROGBITS, 0);
+      Ctx->getELFSection(".debug_types.dwo", DebugSecType, 0);
   DwarfAbbrevDWOSection =
-      Ctx->getELFSection(".debug_abbrev.dwo", ELF::SHT_PROGBITS, 0);
+      Ctx->getELFSection(".debug_abbrev.dwo", DebugSecType, 0);
   DwarfStrDWOSection =
-      Ctx->getELFSection(".debug_str.dwo", ELF::SHT_PROGBITS,
+      Ctx->getELFSection(".debug_str.dwo", DebugSecType,
                          ELF::SHF_MERGE | ELF::SHF_STRINGS, 1, "");
   DwarfLineDWOSection =
-      Ctx->getELFSection(".debug_line.dwo", ELF::SHT_PROGBITS, 0);
+      Ctx->getELFSection(".debug_line.dwo", DebugSecType, 0);
   DwarfLocDWOSection =
-      Ctx->getELFSection(".debug_loc.dwo", ELF::SHT_PROGBITS, 0);
+      Ctx->getELFSection(".debug_loc.dwo", DebugSecType, 0);
   DwarfStrOffDWOSection =
-      Ctx->getELFSection(".debug_str_offsets.dwo", ELF::SHT_PROGBITS, 0);
-  DwarfAddrSection = Ctx->getELFSection(".debug_addr", ELF::SHT_PROGBITS, 0);
+      Ctx->getELFSection(".debug_str_offsets.dwo", DebugSecType, 0);
+  DwarfAddrSection = Ctx->getELFSection(".debug_addr", DebugSecType, 0);
 
   // DWP Sections
   DwarfCUIndexSection =
-      Ctx->getELFSection(".debug_cu_index", ELF::SHT_PROGBITS, 0);
+      Ctx->getELFSection(".debug_cu_index", DebugSecType, 0);
   DwarfTUIndexSection =
-      Ctx->getELFSection(".debug_tu_index", ELF::SHT_PROGBITS, 0);
+      Ctx->getELFSection(".debug_tu_index", DebugSecType, 0);
 
   StackMapSection =
       Ctx->getELFSection(".llvm_stackmaps", ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
 
   FaultMapSection =
       Ctx->getELFSection(".llvm_faultmaps", ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
 
   EHFrameSection =

llvm/trunk/lib/MC/MCSectionELF.cpp

void MCSectionELF::PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
   else if (Type == ELF::SHT_NOBITS)
     OS << "nobits";
   else if (Type == ELF::SHT_NOTE)
     OS << "note";
   else if (Type == ELF::SHT_PROGBITS)
     OS << "progbits";
   else if (Type == ELF::SHT_X86_64_UNWIND)
     OS << "unwind";
+  else if (Type == ELF::SHT_MIPS_DWARF)
+    // Print hex value of the flag while we do not have
+    // any standard symbolic representation of the flag.
+    OS << "0x7000001e";
   else
     report_fatal_error("unsupported type 0x" + Twine::utohexstr(Type) +
                        " for section " + getSectionName());
 
   if (EntrySize) {
     assert(Flags & ELF::SHF_MERGE);
     OS << "," << EntrySize;
   }

llvm/trunk/test/DebugInfo/Mips/InlinedFnLocalVar.ll

 ; RUN: llc -mtriple mips-linux-gnu -O2 %s -o - | FileCheck %s
 ; Check struct X for dead variable xyz from inlined function foo.
 
-; CHECK: .section .debug_info,"",@progbits
+; CHECK: .section .debug_info,"",@0x7000001e
 ; CHECK:  DW_TAG_structure_type
 ; CHECK-NEXT: info_string
 
 source_filename = "test/DebugInfo/Mips/InlinedFnLocalVar.ll"
 
 @i = common global i32 0, !dbg !0
 
 ; Function Attrs: nounwind readnone