[MC] Accept a numeric value as an ELF section header's type

GAS supports specification of section header's type using a numeric
value [1]. This patch brings the same functionality to LLVM. That allows
to setup some target-specific section types belong to the SHT_LOPROC -
SHT_HIPROC range. If we attempt to print unknown section type, MCSectionELF
class shows an error message. It's better than print sole '@' sign
without any section type name.

In case of MIPS, example of such section's type is SHT_MIPS_DWARF.
Without the patch we will have to implement some workarounds
in probably not-MIPS-specific part of code base to convert SHT_MIPS_DWARF
to the @progbits while printing assembly and to assign SHT_MIPS_DWARF for
@progbits sections named .debug_* if we encounter such section in
an input assembly.

[1] https://sourceware.org/binutils/docs/as/Section.html

Differential Revision: https://reviews.llvm.org/D29719

llvm-svn: 297446

2 files changed, 9 insertions, 2 deletions

diff --git a/llvm/lib/MC/MCParser/ELFAsmParser.cpp b/llvm/lib/MC/MCParser/ELFAsmParser.cpp
index fff081f0445..8838f16d60a 100644
--- a/llvm/lib/MC/MCParser/ELFAsmParser.cpp
+++ b/llvm/lib/MC/MCParser/ELFAsmParser.cpp
@@ -395,7 +395,10 @@ bool ELFAsmParser::maybeParseSectionType(StringRef &TypeName) {
     return TokError("expected '@<type>', '%<type>' or \"<type>\"");
   if (!L.is(AsmToken::String))
     Lex();
-  if (getParser().parseIdentifier(TypeName))
+  if (L.is(AsmToken::Integer)) {
+    TypeName = getTok().getString();
+    Lex();
+  } else if (getParser().parseIdentifier(TypeName))
     return TokError("expected identifier in directive");
   return false;
 }
@@ -580,7 +583,7 @@ EndStmt:
       Type = ELF::SHT_NOTE;
     else if (TypeName == "unwind")
       Type = ELF::SHT_X86_64_UNWIND;
-    else
+    else if (TypeName.getAsInteger(0, Type))
       return TokError("unknown section type");
   }
 
diff --git a/llvm/lib/MC/MCSectionELF.cpp b/llvm/lib/MC/MCSectionELF.cpp
index fdd9239a0f1..c73fafe151b 100644
--- a/llvm/lib/MC/MCSectionELF.cpp
+++ b/llvm/lib/MC/MCSectionELF.cpp
@@ -12,6 +12,7 @@
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCSectionELF.h"
 #include "llvm/Support/ELF.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cassert>
 
@@ -140,6 +141,9 @@ void MCSectionELF::PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
     OS << "progbits";
   else if (Type == ELF::SHT_X86_64_UNWIND)
     OS << "unwind";
+  else
+    report_fatal_error("unsupported type 0x" + Twine::utohexstr(Type) +
+                       " for section " + getSectionName());
 
   if (EntrySize) {
     assert(Flags & ELF::SHF_MERGE);