[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

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.

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;
+  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 =

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