[DEMO]

[grimar]

Summary

This one is not for reviews, just for demo.

With this combination of patches, LLD output is similar with bfd for FreeBSD pmbr (protective mbr) loader.

[grimar]

ELF/Writer.cpp

195

This part is even excessive here. Since there is no phdrs, fixSectionAlignments() do nothing for binary output case.

ELF/Target.cpp

RelExpr X86TargetInfo::getRelExpr(uint32_t Type, const SymbolBody &S) const {
   default:
     return R_ABS;
   case R_386_TLS_GD:
     return R_TLSGD;
   case R_386_TLS_LDM:
     return R_TLSLD;
   case R_386_PLT32:
     return R_PLT_PC;
+  case R_386_PC16:
   case R_386_PC32:
     return R_PC;
   case R_386_GOTPC:
     return R_GOTONLY_PC_FROM_END;
   case R_386_TLS_IE:
     return R_GOT;
   case R_386_GOT32:
   case R_386_GOT32X:
void X86TargetInfo::writePlt(uint8_t *Buf, uint64_t GotEntryAddr,
   write32le(Buf + 12, -Index * PltEntrySize - PltHeaderSize - 16);
 }
 
 uint64_t X86TargetInfo::getImplicitAddend(const uint8_t *Buf,
                                           uint32_t Type) const {
   switch (Type) {
   default:
     return 0;
+  case R_386_16:
+  case R_386_PC16:
   case R_386_32:
   case R_386_GOT32:
   case R_386_GOT32X:
   case R_386_GOTOFF:
   case R_386_GOTPC:
   case R_386_PC32:
   case R_386_PLT32:
   case R_386_TLS_LE:
     return read32le(Buf);
   }
 }
 
 void X86TargetInfo::relocateOne(uint8_t *Loc, uint32_t Type,
                                 uint64_t Val) const {
+  // R_386_PC16 and R_386_16 are not part of the current i386 psABI. They are
+  // used by 16-bit x86 objects, like boot loaders.
+  if (Type == R_386_16 || Type == R_386_PC16) {
+    write16le(Loc, Val);
+    return;
+  }
   checkInt<32>(Loc, Val, Type);
   write32le(Loc, Val);
 }
 
 void X86TargetInfo::relaxTlsGdToLe(uint8_t *Loc, uint32_t Type,
                                    uint64_t Val) const {
   // Convert
   //   leal x@tlsgd(, %ebx, 1),

ELF/Writer.cpp

template <class ELFT> void Writer<ELFT>::run() {
   // finalizeSections does that.
   finalizeSections();
   if (ErrorCount)
     return;
 
   if (Config->Relocatable) {
     assignFileOffsets();
   } else {
-    Phdrs = Script<ELFT>::X->hasPhdrsCommands() ? Script<ELFT>::X->createPhdrs()
-                                                : createPhdrs();
+    // Binary output does not have PHDRS.
+    if (!Config->OFormatBinary) {
+      Phdrs = Script<ELFT>::X->hasPhdrsCommands()
+                  ? Script<ELFT>::X->createPhdrs()
       addPtArmExid(Phdrs);
       fixHeaders();
+    }
+
     if (ScriptConfig->HasSections) {
       Script<ELFT>::X->assignAddresses(Phdrs);
     } else {
+      if (!Config->OMagic)
         fixSectionAlignments();
       assignAddresses();
     }
 
     if (!Config->OFormatBinary)
       assignFileOffsets();
     else
       assignFileOffsetsBinary();
 

test/ELF/oformat-binary-ttext.s

+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+
+# RUN: ld.lld -N -Ttext 0x100 -o %t.out %t --oformat binary
+# RUN: od -t x1 -v %t.out | FileCheck %s --check-prefix=BIN
+
+# BIN:      0000000 90 00 00 00 00 00 00 00
+# BIN-NEXT: 0000010
+# BIN-NOT:  0000020
+
+## The same but without OMAGIC.
+# RUN: ld.lld -Ttext 0x100 -o %t.out %t --oformat binary
+# RUN: od -t x1 -v %t.out | FileCheck %s --check-prefix=BIN
+
+.text
+.globl _start
+_start:
+ nop