[PATCH] D29719: [MC] Accept and print a numeric value as an ELF section header's type

[Simon Atanasyan via llvm-commits]

In general, it's better to have a text code. But I do not see any
disadvantages in being compatible with GAS and being able to accept
assembly which accepted by GAS. The numeric section types do not looks
as an ugly hack.

As to me, inventing such "@type" code can be done in parallel. It is a
long process because we have to involve many people.

On Fri, Feb 24, 2017 at 3:57 PM, Rafael Avila de Espindola
<rafael.espindola at gmail.com> wrote:
> Wouldn't it be better to define a @newtype value?
>
> Cheers,
> Rafael
>
> Simon Atanasyan via Phabricator <reviews at reviews.llvm.org> writes:
>
>> atanasyan created this revision.
>>
>> 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 and print some target-specific section types belong to the SHT_LOPROC - SHT_HIPROC range.
>>
>>
>>
>> [1] https://sourceware.org/binutils/docs/as/Section.html
>>
>>
>> Repository:
>>   rL LLVM
>>
>> https://reviews.llvm.org/D29719
>>
>> Files:
>>   lib/MC/MCParser/ELFAsmParser.cpp
>>   lib/MC/MCSectionELF.cpp
>>   test/MC/ELF/section-numeric-type.s
>>
>>
>> Index: test/MC/ELF/section-numeric-type.s
>> ===================================================================
>> --- /dev/null
>> +++ test/MC/ELF/section-numeric-type.s
>> @@ -0,0 +1,26 @@
>> +// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux-gnu %s -o - \
>> +// RUN:   | llvm-readobj -s -t | FileCheck --check-prefix=OBJ %s
>> +
>> +// RUN: llvm-mc -filetype=asm -triple=x86_64-pc-linux-gnu %s -o - \
>> +// RUN:   | FileCheck --check-prefix=ASM %s
>> +
>> +  .section .sec1,"a", at 0x70000001
>> +  .section .sec2,"a", at 1879048193
>> +  .section .sec3,"a", at 0x7fffffff
>> +
>> +// OBJ:      Section {
>> +// OBJ:        Name: .sec1
>> +// OBJ-NEXT:   Type: SHT_X86_64_UNWIND (0x70000001)
>> +// OBJ:      }
>> +// OBJ:      Section {
>> +// OBJ:        Name: .sec2
>> +// OBJ-NEXT:   Type: SHT_X86_64_UNWIND (0x70000001)
>> +// OBJ:      }
>> +// OBJ:      Section {
>> +// OBJ:        Name: .sec3
>> +// OBJ-NEXT:   Type: (0x7FFFFFFF)
>> +// OBJ:      }
>> +
>> +// ASM: .section  .sec1,"a", at unwind
>> +// ASM: .section  .sec2,"a", at unwind
>> +// ASM: .section  .sec3,"a", at 0x7fffffff
>> Index: lib/MC/MCSectionELF.cpp
>> ===================================================================
>> --- lib/MC/MCSectionELF.cpp
>> +++ lib/MC/MCSectionELF.cpp
>> @@ -13,6 +13,7 @@
>>  #include "llvm/MC/MCExpr.h"
>>  #include "llvm/MC/MCSymbol.h"
>>  #include "llvm/Support/ELF.h"
>> +#include "llvm/Support/Format.h"
>>  #include "llvm/Support/raw_ostream.h"
>>
>>  using namespace llvm;
>> @@ -142,6 +143,8 @@
>>      OS << "progbits";
>>    else if (Type == ELF::SHT_X86_64_UNWIND)
>>      OS << "unwind";
>> +  else
>> +    OS << format_hex(Type, 0);
>>
>>    if (EntrySize) {
>>      assert(Flags & ELF::SHF_MERGE);
>> Index: lib/MC/MCParser/ELFAsmParser.cpp
>> ===================================================================
>> --- lib/MC/MCParser/ELFAsmParser.cpp
>> +++ lib/MC/MCParser/ELFAsmParser.cpp
>> @@ -391,7 +391,10 @@
>>      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;
>>  }
>> @@ -557,7 +560,7 @@
>>        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");
>>    }
>>
>>
>>
>> Index: test/MC/ELF/section-numeric-type.s
>> ===================================================================
>> --- /dev/null
>> +++ test/MC/ELF/section-numeric-type.s
>> @@ -0,0 +1,26 @@
>> +// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux-gnu %s -o - \
>> +// RUN:   | llvm-readobj -s -t | FileCheck --check-prefix=OBJ %s
>> +
>> +// RUN: llvm-mc -filetype=asm -triple=x86_64-pc-linux-gnu %s -o - \
>> +// RUN:   | FileCheck --check-prefix=ASM %s
>> +
>> +  .section .sec1,"a", at 0x70000001
>> +  .section .sec2,"a", at 1879048193
>> +  .section .sec3,"a", at 0x7fffffff
>> +
>> +// OBJ:      Section {
>> +// OBJ:        Name: .sec1
>> +// OBJ-NEXT:   Type: SHT_X86_64_UNWIND (0x70000001)
>> +// OBJ:      }
>> +// OBJ:      Section {
>> +// OBJ:        Name: .sec2
>> +// OBJ-NEXT:   Type: SHT_X86_64_UNWIND (0x70000001)
>> +// OBJ:      }
>> +// OBJ:      Section {
>> +// OBJ:        Name: .sec3
>> +// OBJ-NEXT:   Type: (0x7FFFFFFF)
>> +// OBJ:      }
>> +
>> +// ASM: .section  .sec1,"a", at unwind
>> +// ASM: .section  .sec2,"a", at unwind
>> +// ASM: .section  .sec3,"a", at 0x7fffffff
>> Index: lib/MC/MCSectionELF.cpp
>> ===================================================================
>> --- lib/MC/MCSectionELF.cpp
>> +++ lib/MC/MCSectionELF.cpp
>> @@ -13,6 +13,7 @@
>>  #include "llvm/MC/MCExpr.h"
>>  #include "llvm/MC/MCSymbol.h"
>>  #include "llvm/Support/ELF.h"
>> +#include "llvm/Support/Format.h"
>>  #include "llvm/Support/raw_ostream.h"
>>
>>  using namespace llvm;
>> @@ -142,6 +143,8 @@
>>      OS << "progbits";
>>    else if (Type == ELF::SHT_X86_64_UNWIND)
>>      OS << "unwind";
>> +  else
>> +    OS << format_hex(Type, 0);
>>
>>    if (EntrySize) {
>>      assert(Flags & ELF::SHF_MERGE);
>> Index: lib/MC/MCParser/ELFAsmParser.cpp
>> ===================================================================
>> --- lib/MC/MCParser/ELFAsmParser.cpp
>> +++ lib/MC/MCParser/ELFAsmParser.cpp
>> @@ -391,7 +391,10 @@
>>      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;
>>  }
>> @@ -557,7 +560,7 @@
>>        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");
>>    }
>>



-- 
Simon Atanasyan